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## Complete Summary

#### GUIDELINE TITLE

Dementia and movement disorders.

#### BIBLIOGRAPHIC SOURCE(S)

Dormont D, Seidenwurm DJ, Davis PC, Brunberg JA, De La Paz RL, Hackney
DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II,
Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic
Imaging. Dementia and movement disorders. \[online publication\]. Reston
(VA): American College of Radiology (ACR); 2007. 15 p. \[86 references\]

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version: Braffman B, Drayer BP,
Anderson RE, Davis PC, Deck MD, Hasso AN, Johnson BA, Masaryk T,
Pomeranz SJ, Seidenwurm D, Tanenbaum L, Masdeu JC. Dementia. American
College of Radiology. ACR Appropriateness Criteria. Radiology 2000
Jun;215(Suppl):525-33. \[31 references\]

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

### COMPLETE SUMMARY CONTENT

 SCOPE\
 METHODOLOGY - including Rating Scheme and Cost Analysis\
 RECOMMENDATIONS\
 EVIDENCE SUPPORTING THE RECOMMENDATIONS\
 BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS\
 QUALIFYING STATEMENTS\
 IMPLEMENTATION OF THE GUIDELINE\
 INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT
CATEGORIES\
 IDENTIFYING INFORMATION AND AVAILABILITY\
 DISCLAIMER

### SCOPE

#### DISEASE/CONDITION(S)

Dementia, including:

-   Alzheimer\'s disease (AD)

-   Frontotemporal dementia (FTD)

-   Lewy body disease (DLB)

-   Vascular dementia (VaD)

-   Creutzfeldt-Jakob disease (CJD)

-   Normal-pressure hydrocephalus (NPH)

-   Huntington\'s disease (HD)

-   Neurodegeneration with brain iron accumulation (NBIA)

-   Parkinson\'s disease (PD)

-   Multiple system atrophy (MSA)

-   Progressive supranuclear palsy (PSP)

-   Amyotrophic lateral disease (ALS)

#### GUIDELINE CATEGORY

Diagnosis\
Evaluation

#### CLINICAL SPECIALTY

Family Practice\
Geriatrics\
Internal Medicine\
Neurology\
Radiology

#### INTENDED USERS

Health Plans\
Hospitals\
Managed Care Organizations\
Physicians\
Utilization Management

#### GUIDELINE OBJECTIVE(S)

To evaluate the appropriateness of initial radiologic examinations for
dementia

#### TARGET POPULATION

Patients with dementia and movement disorders

#### INTERVENTIONS AND PRACTICES CONSIDERED

1.  Magnetic resonance imaging (MRI)

    -   Head without contrast

    -   Head with and without contrast

    -   Spectroscopy, head

    -   Functional MRI (fMRI), head

    -   Spine without contrast

    -   Spine with and without contrast

2.  Magnetic resonance angiography (MRA) head and/or neck

3.  Computed tomography (CT), head

    -   Without contrast

    -   With and without contrast

4.  Fluorodeoxyglucose positron emission tomography (FDG-PET), head

5.  Nuclear medicine (NUC)

    -   Single photon emission computed tomography (SPECT)

    -   Cisternography

6.  Ultrasound (US) carotid duplex

#### MAJOR OUTCOMES CONSIDERED

Utility of radiologic procedures in differential diagnosis of dementia
and movement disorders

### METHODOLOGY

#### METHODS USED TO COLLECT/SELECT EVIDENCE

Searches of Electronic Databases

#### DESCRIPTION OF METHODS USED TO COLLECT/SELECT THE EVIDENCE

The guideline developer performed literature searches of recent
peer-reviewed medical journals and the major applicable articles were
identified and collected.

#### NUMBER OF SOURCE DOCUMENTS

Not stated

#### METHODS USED TO ASSESS THE QUALITY AND STRENGTH OF THE EVIDENCE

Weighting According to a Rating Scheme (Scheme Not Given)

#### RATING SCHEME FOR THE STRENGTH OF THE EVIDENCE

Not stated

#### METHODS USED TO ANALYZE THE EVIDENCE

Systematic Review with Evidence Tables

#### DESCRIPTION OF THE METHODS USED TO ANALYZE THE EVIDENCE

One or two topic leaders within a panel assume the responsibility of
developing an evidence table for each clinical condition, based on
analysis of the current literature. These tables serve as a basis for
developing a narrative specific to each clinical condition.

#### METHODS USED TO FORMULATE THE RECOMMENDATIONS

Expert Consensus (Delphi)

#### DESCRIPTION OF METHODS USED TO FORMULATE THE RECOMMENDATIONS

Since data available from existing scientific studies are usually
insufficient for meta-analysis, broad-based consensus techniques are
needed for reaching agreement in the formulation of the appropriateness
criteria. The American College of Radiology (ACR) Appropriateness
Criteria panels use a modified Delphi technique to arrive at consensus.
Serial surveys are conducted by distributing questionnaires to
consolidate expert opinions within each panel. These questionnaires are
distributed to the participants along with the evidence table and
narrative as developed by the topic leader(s). Questionnaires are
completed by participants in their own professional setting without
influence of the other members. Voting is conducted using a scoring
system from 1-9, indicating the least to the most appropriate imaging
examination or therapeutic procedure. The survey results are collected,
tabulated in anonymous fashion, and redistributed after each round. A
maximum of three rounds is conducted and opinions are unified to the
highest degree possible. Eighty percent agreement is considered a
consensus. This modified Delphi technique enables individual, unbiased
expression, is economical, easy to understand, and relatively simple to
conduct.

If consensus cannot be reached by the Delphi technique, the panel is
convened and group consensus techniques are utilized. The strengths and
weaknesses of each test or procedure are discussed and consensus reached
whenever possible. If \"No consensus\" appears in the rating column,
reasons for this decision are added to the comment sections.

#### RATING SCHEME FOR THE STRENGTH OF THE RECOMMENDATIONS

Not applicable

#### COST ANALYSIS

A formal cost analysis was not performed and published cost analyses
were not reviewed.

#### METHOD OF GUIDELINE VALIDATION

Internal Peer Review

#### DESCRIPTION OF METHOD OF GUIDELINE VALIDATION

Criteria developed by the Expert Panels are reviewed by the American
College of Radiology (ACR) Committee on Appropriateness Criteria.

### RECOMMENDATIONS

#### MAJOR RECOMMENDATIONS

**ACR Appropriateness Criteria®**

**Clinical Condition: Dementia and Movement Disorders**

**Variant 1: Probable Alzheimer\'s disease.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  7            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       6                                              Low
  contrast                                                             

  FDG-PET head          6            For problem solving.              High

  NUC SPECT head        5            For problem solving.              High

  CT head with and      4                                              Low
  without contrast                                                     

  MRI spectroscopy head 4                                              None

  fMRI head             2            For research purposes.            None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 2: Possible Alzheimer\'s disease.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  8            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  FDG-PET head          7            For problem solving.              High

  CT head without       6                                              Low
  contrast                                                             

  NUC SPECT head        6            For problem solving.              High

  CT head without and   5                                              Low
  with contrast                                                        

  MRI spectroscopy head 4                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 3: Suspected vascular dementia or mixed vascular dementia and
Alzheimer\'s disease.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head with and     8            See comments regarding contrast   None
  without contrast                   in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       6                                              Low
  contrast                                                             

  FDG-PET head          6            For problem solving.              High

  MRA head and or neck  6            See comments regarding contrast   None
                                     in text under \"Anticipated       
                                     Expectations.\"                   

  CTA head and or neck  6                                              Low

  US carotid duplex     6                                              None

  CT head with and      5                                              Low
  without contrast                                                     

  NUC SPECT head        5            For problem solving.              High

  MRI spectroscopy head 2                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 4: Frontotemporal dementia.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  8            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  FDG-PET head          7            For problem solving.              High

  CT head without       6                                              Low
  contrast                                                             

  NUC SPECT head        6            For problem solving.              High

  CT head without and   4                                              Low
  with contrast                                                        

  MRI spectroscopy head 4                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 5: Dementia with Lewy bodies.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  8            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  NUC SPECT head        7            For problem solving.              High

  FDG-PET head          7            For problem solving.              High

  CT head without       6                                              Low
  contrast                                                             

  CT head without and   5                                              Low
  with contrast                                                        

  MRI spectroscopy head 3                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 6: Suspected prion disease (Creutzfeld-Jakob, iatrogenic CJ or
variant CJ).**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8            Include diffusion weighted        None
  contrast                           imaging.                          

  MRI head with and     8            Include diffusion weighted        None
  without contrast                   imaging. See comments regarding   
                                     contrast in text under            
                                     \"Anticipated Expectations.\"     

  CT head without       6                                              Low
  contrast                                                             

  MRI spectroscopy head 5                                              None

  CT head with and      5                                              Low
  without contrast                                                     

  NUC SPECT head        5            For problem solving               High

  FDG-PET head          5            For problem solving.              High

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 7: Suspected normal pressure hydrocephalus.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head with and     8            See comments regarding contrast   None
  without contrast                   in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       6                                              Low
  contrast                                                             

  NUC cisternography    6            For problem solving.              Low

  CT head with and      5                                              Low
  without contrast                                                     

  MRI spectroscopy head 3                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 8: Suspected Huntington disease.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  7            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       5                                              Low
  contrast                                                             

  NUC SPECT head        5            For problem solving.              High

  FDG-PET head          5            For problem solving.              High

  MRI spectroscopy head 3                                              None

  CT head without and   3                                              Low
  with contrast                                                        

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 9: Clinical features suggestive of neurodegeneration with
brain iron accumulation (NBIA).**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head with and     7            See comments regarding contrast   None
  without contrast                   in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       5                                              Low
  contrast                                                             

  CT head with and      4                                              Low
  without contrast                                                     

  MRI spectroscopy head 3                                              None

  fMRI head             3                                              None

  NUC SPECT head        3            For problem solving.              High

  FDG-PET head          3            For problem solving.              High

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 10: Parkinson\'s disease: typical clinical features and
responds to levodopa.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      7            For problem solving.              None
  contrast                                                             

  MRI head with and     7            For problem solving. See comments None
  without contrast                   regarding contrast in text under  
                                     \"Anticipated Expectations.\"     

  CT head without       6                                              Low
  contrast                                                             

  NUC SPECT head        6            For problem solving. Specific     High
                                     ligand.                           

  FDG-PET head          6            For problem solving. Dopa PET.    High

  CT head with and      5                                              Low
  without contrast                                                     

  MRI spectroscopy head 3                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 11: Parkinsonian syndrome: atypical clinical features not
responsive to levodopa.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI head without      8                                              None
  contrast                                                             

  MRI head without and  7            See comments regarding contrast   None
  with contrast                      in text under \"Anticipated       
                                     Expectations.\"                   

  NUC SPECT head        6            For problem solving.              High

  FDG-PET head          6            For problem solving.              High

  CT head without       5                                              Low
  contrast                                                             

  CT head without and   4                                              Low
  with contrast                                                        

  MRI spectroscopy head 3                                              None

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Variant 12: Motor neuron disease.**

  -----------------------------------------------------------------------------------
  **Radiologic          **Rating**   **Comments**                      **RRL\***
  Procedure**                                                          
  --------------------- ------------ --------------------------------- --------------
  MRI spine without     8            May need multilevel imaging.      None
  contrast                                                             

  MRI head without      8                                              None
  contrast                                                             

  MRI spine with and    7            May need multilevel imaging. See  None
  without contrast                   comments regarding contrast in    
                                     text under \"Anticipated          
                                     Expectations.\"                   

  MRI head with and     7            See comments regarding contrast   None
  without contrast                   in text under \"Anticipated       
                                     Expectations.\"                   

  CT head without       5                                              Low
  contrast                                                             

  CT head with and      4                                              Low
  without contrast                                                     

  MRI spectroscopy head 3                                              None

  NUC SPECT head        3            For problem solving.              High

  FDG-PET head          3            For problem solving.              High

  fMRI head             2                                              None

  **[Rating                                                            **\*Relative
  Scale]{.underline}:                                                  Radiation
  1=Least appropriate,                                                 Level**
  9=Most appropriate**                                                 
  -----------------------------------------------------------------------------------

Note: Abbreviations used in the tables are listed at the end of the
\"Major Recommendations\" field.

**Summary of Literature Review**

**Dementia**

Dementia affects approximately 7% of the general population older than
65 years, and 30% of people older than 80. It is a clinical state
characterized by a significant loss of function in multiple cognitive
domains that is not due to an impaired level of arousal. Diagnosis of
dementia requires either: 1) assessing an individual\'s current level of
cognitive function and documenting a higher level of intellectual
function in the past, or 2) documenting a decline in intellectual
function by examinations over time. Cognitive defects due to delirium,
restricted brain lesions (e.g., aphasia), and psychiatric problems
(e.g., depression) must be excluded.

Accurate diagnosis of the specific type of dementia is important given
the current availability of therapies such as cholinesterase inhibitors
for Alzheimer\'s disease (AD) that can delay institutionalization.
Moreover, there is significant prognostic value in establishing a
diagnosis as it enables the clinician to provide anticipatory guidance
to the patient and family, to more accurately predict the future course,
to facilitate legal and financial planning, and to assist with providing
access to community resources.

*Alzheimer\'s Disease*

Alzheimer\'s disease is the most frequent type of dementia in the U.S.
and most European countries, comprising about 50%-80% of subjects in
various clinicopathological series. The National Institute of
Neurological and Communicative Disorders and Stroke (NINCDS) and the
Alzheimer\'s Disease and Related Disorders Association (ADRDA) have
established the criteria for the definite, probable, and possible
diagnosis of AD. Criteria for a definite diagnosis are histologic
evidence of AD obtained from a biopsy or autopsy in the presence of the
clinical criteria for probable AD. Criteria for a diagnosis of probable
AD include: 1) the insidious onset and progressive worsening of
dementia; 2) prominent difficulty with memory (especially retention and
retrieval of new material); 3) onset after age 60; 4) no focal signs or
gait difficulties on neurologic examination, especially early in the
course; and 5) exclusion of other causes of dementia due to systemic
disorders or other intracranial disorders. To exclude other intracranial
disorders that might cause dementia (including stroke, intra-axial or
extra-axial tumors, subdural hematomas, hydrocephalus, and
Creutzfeldt-Jakob disease), neuroimaging (magnetic resonance imaging
\[MRI\] or computed tomography \[CT\]) should be performed. If
available, MRI is preferable to CT because of its greater sensitivity in
detecting most intracranial pathologies. From 80% to 85% of patients who
meet the criteria for probable AD have histologic evidence of AD.
However, a prospective neuropathological study has demonstrated that in
a population older than 85 years, the prevalence of neuropathologically
defined AD was at least two times higher (33%) than the prevalence of
clinically diagnosed AD (16%).

Criteria for a diagnosis of possible AD include: 1) variations in the
onset, presentation, or clinical course of typical AD, or 2) the
presence of a second systemic or intracranial disorder sufficient to
produce dementia, but which is not considered to be the cause of the
dementia. In either of these scenarios, MRI or (CT, if MRI is
unavailable) should be performed to determine whether the patient has
other intracranial abnormalities. Patients with possible AD have a
greater incidence of other significant intracranial pathologies detected
on neuroimaging studies than patients with probable AD.

A new clinical entity, mild cognitive impairment (MCI), has been defined
more recently. It is a cognitive decline greater than expected for an
individual\'s age and education level but that does not interfere
notably with activities of daily life. More than half of the patients
with MCI progress to dementia within 5 years. The amnestic subtype of
MCI may constitute a prodromal stage of AD.

The primary role of neuroimaging in the workup of patients with probable
or possible AD is to exclude other significant intracranial
abnormalities. It is important to evaluate critically the role of
imaging in assessing dementias, because the cost of a false positive
diagnosis of AD, especially in cases of MCI, are very high. Recent
investigations document specific diagnostic neuroimaging features in AD,
suggesting an additional direct role of neuroimaging. Positron emission
tomography (PET) studies with flourine-18-fluorodeoxyglucose (FDG) show
characteristic reductions of regional glucose metabolic rates in
patients with probable and definite AD in the parietal, temporal, and
posterior cingulate regions. PET accurately discriminates AD patients
from normal subjects with a sensitivity of 96% and specificity of 100%.
Metabolic neuroimaging studies using FDG paradoxically suggest that
hippocampal dysfunction is absent in AD and MCI, but more recently
automated FDG-PET analysis has demonstrated reduced hippocampal
metabolism in MCI and AD, suggesting that the previous negative results
were due to methodological problems. Quantitative FDG-PET measures may
improve prediction of the conversion to AD in patients with MCI. A new
promising technique for diagnosing AD is the use of molecular imaging
with PET to detect in vivo Abeta amyloid in the brain of patients with
AD. This has been achieved using the Pittsburgh compound-B (PIB). This
method, however, is not widely available in clinical practice because of
the very short half-life of this compound. The American Academy of
Neurology (AAN) consensus group did not recommend PET for diagnosing AD.

MRI-based volumetric measurements of the hippocampal formation are
significantly smaller in patients with mild AD compared with controls
and compared to patients with other forms of dementia. This finding
correlates with a neuropathologic hallmark of AD, which is focal atrophy
of the hippocampal formation. MRI volumetric calculations permit
differentiation of controls from patients with AD accurately in 85%-100%
of cases. Although it is not as accurate as MRI, CT also permits
detection of hippocampal atrophy in AD patients. Medial temporal lobe
atrophy has also been observed in MCI compared to cognitively normal
individuals. The presence of this sign has a high predictive value for
the progression to dementia. The AAN did not recommend quantitative
volumetry of the hippocampus.

Regional cerebral blood flow determined using single photon emission
computed tomography (SPECT) imaging with Tc-99m hexamethyl propylene
amine oxime (HMPAO) shows bilateral temporoparietal or hippocampal
hypoperfusion in patients with AD. Whether brain SPECT contributes
substantially to diagnostic accuracy after a careful clinical
examination using current diagnostic criteria is controversial. An
evidence-based review performed by the AAN concluded that SPECT imaging
cannot be recommended for either the initial or the differential
diagnosis of suspected dementia because it has not demonstrated
superiority to clinical criteria. PET imaging is also not recommended
for routine use at this time.

Hydrogen-1 MR spectroscopy (MRS) may permit identification of mild to
moderate AD with a specificity and sensitivity that suggest the
potential for clinical usefulness. Studies of automated MRS for AD
diagnosis have reported high sensitivity and moderate specificity.
Prospective studies are still lacking to validate this method for
diagnosing AD. Functional MRI, diffusion tensor MRI, and perfusion MRI
have been used in AD and MCI patients but are still investigational
tools at this time.

Of these neuroimaging tests, MR volumetric analysis of the hippocampal
formation and PET assessment of regional glucose metabolism are the most
diagnostic of AD. Determining the specific clinical applications of
either of these studies in patients with probable or possible AD, MCI,
or atypical dementias awaits additional investigation. In patients with
a diagnosis of probable AD, either of these neuroimaging studies may
permit the accuracy to increase from the 80%-85% range to the 90%-100%
range, depending on the prevalence of the disorder in the subject
population. In patients with possible AD or other atypical dementias,
these neuroimaging studies may also permit a more accurate diagnosis.
Volumetric MRI studies, PET studies, and possibly functional MRI likely
will play an important role in the evaluation of new therapeutic drug
strategies in AD.

*Frontotemporal Dementia*

Frontotemporal dementia (FTD) is a neurodegenerative disorder commonly
mistaken for AD. Pathologically, it includes a heterogeneous group of
sporadic and familial neuropsychiatric disorders. Pick\'s disease is one
of the neuropathological entities of FTD. Unlike AD, which increases in
frequency with age, FTD is rare after the age of 75. The Work Group on
Frontotemporal Dementia and Pick\'s Disease reassessed clinical and
neuropathological criteria for FTD in 2001.

The clinical criteria for FTD are:

-   The development of behavioral or cognitive deficits manifested by
    either a) early and progressive change in personality, characterized
    by difficulty in modulating behavior, often resulting in
    inappropriate responses or activities, or b) early and progressive
    change in language, characterized by problems with expression of
    language or severe naming difficulty and problems with word meaning

-   The deficits outlined in 1a or 1b cause significant impairment in
    social or occupational functioning and represent a significant
    decline from a previous level of functioning

-   The course is characterized by a gradual onset and continuing
    decline in function

-   The deficits outlined in 1a or 1b are not due to other nervous
    system conditions (e.g., cerebrovascular disease), systemic
    conditions (e.g., hypothyroidism), or substance-induced conditions

-   The deficits do not occur exclusively during a delirium

-   The disturbance is not better accounted for by a psychiatric
    diagnosis

MRI may show atrophy of the anterior temporal and frontal lobes. PET
studies assessing regional glucose metabolism with FDG show the
metabolic disturbance most prominent in the frontal and temporal lobes.
SPECT studies assessing regional cerebral perfusion with HMPAO show
frontal hypoperfusion. Although PET and SPECT could help to make the
differential diagnosis between AD and FTD, they are not recommended for
routine use at the present time.

*Lewy Body Disease*

Dementia with Lewy bodies (DLB) has been recently identified among
demented patients. This description has been driven by autopsy studies
showing that 15%-25% of elderly demented patients have Lewy bodies in
their brainstem and cortex. Among demented elderly, DLB may constitute
the most common neurodegenerative pathologic subgroup after pure AD.
Antemortem diagnosis of DLB is clinically useful because, 1) DLB is
often characterized by a rapidly progressive clinical syndrome, 2)
important risks are related to the use of neuroleptic medication, and 3)
DLB patients may be particularly responsive to cholinesterase
inhibitors.

The DLB consortium has defined criteria for probable and possible DLB
disease and has updated them recently. Briefly, the criteria include
central features (essential for the diagnosis of DLB), core features
(two are necessary for the diagnosis of probable DLB, one for possible),
suggestive features, and supportive features. Central features include:
dementia; prominent memory impairment not necessarily present in the
early stages but usually evident with progression; and deficits on tests
of attention, executive function, and visuospatial ability. Core
features include: fluctuating cognition, recurrent visual
hallucinations, and spontaneous features of Parkinsonism. Functional
imaging of the dopamine transporter (DAT) using SPECT can help to
distinguish DLB from AD. DAT striatal activity is normal in AD and low
in DLB. Occipital hypoperfusion has been demonstrated using SPECT and
occipital hypometabolism using PET. In patients with DLB, MRI shows a
preservation of hippocampal and medial temporal lobe volume, no
occipital lobe atrophy despite abnormality on functional imaging, and
atrophy of the putamen.

Many patients with Parkinson\'s disease (PD) develop dementia (PDD), in
most cases at least 10 years after onset of motor symptoms. The only
differences between DLB and PDD are age at onset, temporal course, and
possibly levodopa responsivity. DLB should be diagnosed when dementia
occurs before or concurrently with PD, and PDD should be diagnosed when
dementia occurs in the context of well-established PD.

*Vascular Dementia*

Vascular dementia (VaD) constitutes the second most common type of
dementia. The main clinicopathological subtypes are large-vessel VaD and
small-vessel VaD. Most patients with a diagnosis of VaD have
small-vessel disease. VaD can be prevented or arrested by measures that
prevent recurrent infarction (i.e., control of hypertension,
antiplatelet therapy). Cognition may even improve after these factors
are controlled suggesting that at least a portion of dementia is caused
by reversible physiologic changes and not infarction. Therefore,
clinical and radiologic tests that aid in distinguishing VaD from less
treatable forms of dementia may be beneficial.

A diagnosis of VaD is supported by the following findings: 1) the sudden
onset of dysfunction in one or more cognitive domains; 2) a stepwise
deteriorating course; 3) focal neurologic signs, including weakness of
an extremity, exaggeration of deep tendon reflexes, extensor plantar
responses, and gait abnormalities; 4) evidence of stroke risk factors
and systemic vascular disease; and 5) evidence of previous strokes. The
role of neuroimaging, therefore, is to document the presence or absence
of strokes. Reproducibility for the diagnosis of VaD among the different
criteria is very low. At present the preferred diagnostic criteria for
VaD for research protocols are those developed by the National Institute
of Neurological Disorders and Stroke and the Association Internationale
pour la Rechereche et l\'Enseignement en Neurosciences (NINDS-AIREN).
They are probably the most specific, although their sensitivity is
probably low. Interestingly, they include imaging criteria for the
definition of VaD.

NINDS-AIREN criteria for diagnosing VaD define definite, probable, and
possible VaD. The criteria for probable VaD include: dementia;
cerebrovascular disease defined by the presence of focal signs and
evidence of relevant cerebrovascular disease by brain imaging (CT or
MRI); and a relationship between these two disorders. The NINDS-AIREN
imaging criteria for VaD include multiple large-vessel infarcts; single
strategically placed infarct; multiple basal ganglia; and white matter
lacunes or extensive periventricular white matter lesions or
combinations of both type of lesions (small-vessel disease). Precise
operational definitions of MRI NINDS-AIREN criteria for VaD with
interobserver study have been published. Although CT can detect the
presence or absence of infarctions in patients with dementia,
histopathologically verified cases of VaD with normal CT studies have
been reported. Thus MRI is preferable to CT for detecting vascular
lesions in patients with dementia.

Differentiation of VaD from either AD with superimposed cerebrovascular
disease or mixed AD and VaD is especially difficult. When VaD is
diagnosed, this pathologic diagnosis alone is confirmed in about 25% of
cases; more commonly, a mixed disorder with neuropathologic changes of
both AD and VaD is found. On neuroimaging studies, extensive infarctions
(cortical or lacunar or both) and white-matter changes (hyperintense on
T2-weighted MR images or hypodense on CT) in a patient with dementia
favor a clinical diagnosis of VaD or mixed VaD and AD over AD. The
absence or mild extent of these changes in a patient with dementia
argues against a diagnosis of VaD.

FDG-PET in VaD shows multiple focal metabolic defects. Differentiation
between AD and VaD is much better achieved by PET than by SPECT. SPECT
is of little value in differentiating AD from VaD. Magnetic resonance
spectroscopy (MRS) and functional MRI are investigational and, to date,
do not appear to clinically help establish a diagnosis of VaD or mixed
VaD and AD.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and
leukoencephalopathy (CADASIL) is an autosomal dominant hereditary
small-artery vasculopathy caused by mutations in the notch3 gene on
chromosome 19. Clinically, the disease is characterized by migraine with
aura, strokes and progressive subcortical dementia, and mood
disturbances. Usually, the disease begins around the age of 40 with mean
disease duration of 20 years followed by death between the ages of 55
and 65. MRI in these patients shows focal lacunar infarcts and
leukoaraiosis. Lesion load increases with age. Besides familial
anamnesis and clinical history, structural MRI changes in these patients
help to suggest the diagnosis by showing characteristic hyperintense T2
or FLAIR lesions which predominate in the frontal, parietal, and
anterior temporal cortexes, and in the external capsule. Diagnosis is
confirmed by skin biopsy or detection of a pathogenic notch3 mutation on
direct sequencing.

*Creutzfeldt-Jakob-Disease*

Creutzfeldt-Jakob-Disease (CJD) is a fatal neurodegenerative disorder
due to the accumulation of an abnormal form of the human prion protein
PrP^Sc^ in the brain. In humans there are three main forms of CJD: 1)
sporadic CJD (sCJD) which affects patients between the ages of 50 and
75; 2) iatrogenic CJD; and 3) variant CJD (vCJD) which affect younger
patients (average age of onset: 25-30 years). A definite diagnosis of
CJD is based on histopathological findings; however, brain biopsy is
rarely performed in patients with suspected CJD, and autopsy data are
not always available. During life, the diagnosis of probable CJD can be
made on the basis of clinical signs, including a rapidly progressive
dementia associated with upper motor neuron dysfunction, myoclonus,
characteristic EEG (generalized periodic sharp wave complexes),
detection of 14-3-3 proteins in the cerebrospinal fluid (CSF) and
neuroimaging findings. Although some variability exists, the most common
MRI abnormality, other than progressive atrophy, is hyperintense signal
on long-TR images in gray-matter structures, usually in the basal
ganglia or thalami, and less commonly in the cortical gray matter. More
recent MRI studies have demonstrated the value of diffusion-weighted
imaging (DWI) in diagnosing CJD. Cortical abnormalities were present in
70 of 157 patients (45%) but were visible in 35 of 44 patients (80%) of
the available DWI examinations. Basal ganglia were affected in 94
patients (60%), in particular in the caudate nucleus. The most sensitive
sequences were DWI (64%) and PD-weighted (63%). It is suggested that MRI
helps to improve the diagnosis of CJD, and incorporation of MRI in the
diagnostic criteria has been proposed for sCJD.

Marked cerebral hypometabolism on FDG-PET in the early stages of CJD,
when no parenchymal abnormalities are present on MRI has been described.
Similarly, focal hypoperfusion was detected with SPECT using
Nisopropyl-(iodine-123) p-iodoamphetamine (I^123^-IMP) before CT or MRI
showed any abnormalities. Changes in cerebral metabolites using proton
MRS have also been described in patients with CJD.

Variant CJD was described in humans for the first time in 1996. Strong
evidence indicates transmission to humans of bovine spongiform
encephalopathy (BSE) via ingestion of contaminated beef products. As of
August 2006 there have been only 2 human cases in the United States, but
162 cases have been observed in the United Kingdom and 20 in France. In
contrast to sCJD, vCJD affects younger patients and has a relatively
longer duration of illness (median of 14 months as opposed to 4.5
months). In the appropriate clinical context, bilateral hypersignal on a
T2-weighted MRI sequence at the level of the pulvinar (pulvinar sign)
has been described as a useful noninvasive test for diagnosing vCJD.
Histological confirmation of a diagnosis of vCJD can be obtained using
tonsil biopsy.

*Normal-Pressure Hydrocephalus*

Normal-pressure hydrocephalus (NPH) is characterized by the clinical
triad of dementia, gait disturbance, and urinary incontinence. Other
diagnostic features include normal cerebrospinal fluid (CSF) pressure at
lumbar puncture, communicating hydrocephalus documented on MRI or CT,
and ventricular influx but no passage of isotope over the convexities on
radionuclide cisternography (RC).

Because the dementia and other symptoms can be reversible with shunting,
and because patients with NPH who are not shunted may progress
symptomatically, distinction between responders and nonresponders is
important. Several clinical, laboratory, and imaging signs may improve
distinction between responders and nonresponders to shunting. Clinical
features that favor shunt responsiveness include predominance of gait
disturbance, mild to moderate degree of dementia, and rapid clinical
progression of urinary incontinence. MRI or CT findings include at least
moderate ventriculomegaly (with rounded frontal horns and marked
enlargement of the temporal horns and third ventricle), and absence of
or only mild cortical atrophy. Increased CSF flow void through the
cerebral aqueduct on MRI appears to correlate with a good response to
shunt surgery. Cine MRI with inflow technique showing hyperdynamic
aqueductal CSF may also help in identifying shunt-responsive NPH
patients. SPECT cisternography permits more accurate localization of
radionuclide activity than planar cisternography, which partially
superimposes different CSF compartments. One study using quantitative RC
with SPECT found that a higher relative count value in the lateral and
third ventricles was predictive for the patient responding to shunt
surgery.

Recently, evidence-based guidelines have been developed by the INPH
guidelines study group for diagnosing idiopathic normal pressure
hydrocephalus (INPH). In these guidelines, the patients are divided into
probable INPH, possible INPH, or unlikely INPH. Brain imaging features
for diagnosing probable INPH include: ventricular enlargement not
entirely attributable to cerebral atrophy or congenital enlargement
(Evan\'s index = maximal width of frontal horns/maximal width of inner
skull \>0.3); no macroscopic obstruction of CSF flow; and at least one
the following features: enlargement of the temporal horns, callosal
angle of 40° or more, evidence of altered brain water content, and
aqueductal or fourth ventricle flow void on MRI. Other brain imaging
findings, considered as supportive of the diagnosis but not necessary
for probable INPH are: brain imaging performed before onset of symptoms
showing smaller ventricular size; radionuclide cisternogram showing
delayed clearance of radiotracer over the cerebral convexities; cine MRI
study showing increased ventricular flow rate; and a SPECT acetazolamide
challenge showing decreased periventricular perfusion that is not
altered by acetazolamide.

In conclusion, dementia is a major cause of disability and death in
developed countries. The impact of a demented patient on his or her
family is substantial. Neuroimaging studies play a critical role in the
evaluation of dementia to rule out structural causes that may be
reversible and to contribute to the diagnosis of specific types of
dementia with important therapeutic and prognostic implications.

**Degenerative Diseases of the Extrapyramidal System**

The extrapyramidal centers are large subcortical nuclear structures from
which output systems emerge at several points. Since mediation and
control of the corticospinal tract are the most prominent functions of
these output systems, lesions of the extrapyramidal nuclei typically
result in motor dysfunction of various types.

*Huntington\'s Disease*

The usual age of onset of Huntington\'s disease (HD) is in the 4th and
5th decades. It is inherited in an autosomal dominant fashion with
complete penetrance. Clinical manifestations are choreoathetosis,
rigidity, dementia, and emotional disturbance. The Huntington disease
phenotype results from an expanded cytosine, adenine, guanine (CAG)
trinucleotide repeat within the *IT15* gene located on chromosome 4. The
discovery of this mutation permits genetic testing to confirm the
diagnosis of HD, and also to identify presymptomatic subjects who will
develop the disease later in life.

Neuroimaging and pathology studies both show characteristic atrophy of
the caudate and/or putamen. MR also shows signal changes of the
striatum, either hyperintensity or hypointensity on long-TR or long-TE
images. Neuronal loss accompanied by loss of myelin and gliosis likely
results in the hyperintense signal, while iron accumulation likely
accounts for the hypointense signal. Using voxel-based morphometry, it
has been shown that patients with HD have significant volume reductions
in almost all brain structures, including total cerebrum, total white
matter, cerebral cortex, caudate, putamen, globus pallidus, amygdala,
hippocampus, brainstem, and cerebellum when compared with healthy age
matched controls.

Localized 1H nuclear medicine resonance (NMR) spectroscopic studies have
found increased lactate concentrations in the occipital cortex of
symptomatic HD patients when compared with normal controls. Modification
of activation pattern has been demonstrated using functional MRI (fMRI)
during a time discrimination task in presymptomatic HD compared to
control subjects. SPECT studies show hypometabolism of the striatum in
HD and in other types of chorea. Progressive striatal and cortical
dopamine receptor dysfunction in HD has been shown using (11)
C-raclopride PET scans.

*Neurodegeneration with Brain Iron Accumulation*

Neurodegeneration with brain iron accumulation (NBIA) is a heterogeneous
group of disorders characterized by neurodegeneration and excessive iron
deposition in the basal ganglia. The old name for this syndrome is
Hallervorden Spatz disease (HSD). This eponymous term has fallen into
disfavor because of the unethical activities of J. Hallervorden, a
German neuropathologist, during World War II. There are two types of
NBIA: 1) early onset, rapidly progressive (classic) disease and 2) late
onset, slowly progressive (atypical) disease. Clinically, the disorder
is characterized by relentless progression of gait impairment, rigidity,
dystonic posturing, and mental deterioration. The defective gene that
causes most cases of NBIA was identified recently. Most patients with
NBIA and all of those with the early-onset, rapidly progressive type,
have mutations in the gene encoding panthothenate kinase 2 (PANK 2).
Moreover, there is a striking correlation between MRI findings in NBIA
and the presence or absence of PANK 2 mutations. All patients with the
PANK 2 mutation show bilateral areas of hyperintensity within a
hypointense zone in the medial gobus pallidus on T2-weighted images.
This pattern has been described as the \"eye of tiger.\"

*Parkinsonism*

Primary Parkinsonism syndromes include: Parkinson\'s disease (PD),
progressive supranuclear palsy (PSP), and multiple system atrophy (MSA).
They include the disorders previously called striatonigral degeneration
(SND), sporadic olivopontocerebellar atrophy (OPCA), and the Shy-Drager
syndrome. A diagnosis of idiopathic PD is usually based on patient
history and physical examination alone. A significant and lasting
clinical response to dopaminergic therapy is also a key criterion for
diagnosing idiopathic PD. A differentiating between idiopathic PD and
MSA can be difficult early in the course of the disease, with up to 30%
of MSA patients responding to levodopa in a short period. Imaging data
may also be helpful in differentiating MSA from idiopathic PD in
difficult cases.

*Parkinson\'s Disease*

Idiopathic Parkinson\'s disease is relatively common. Between 2%-3% of
the population may be expected to develop Parkinsonism at some time
during life. The age of onset usually ranges between 50 and 60 years.

The neuropathologic hallmarks are loss of neuromelanin-containing
neurons, gliosis and Lewy body formation in the substantia nigra (mainly
the pars compacta), the locus nucleus, the dorsal nucleus of the vagus,
and the substantia innominata. A diminution of the width of the pars
compacta on MRI has been described in PD patients compared to controls
with overlap between groups. This diminished width is thought to reflect
selective neuronal loss of the pars compacta. Other authors have found a
normal appearance of the substantia nigra on T2-weighted images in a
majority of PD patients.

Proton MR spectroscopic studies found an increase in lactate in the
occipital lobe in patients with Parkinson\'s disease compared to
controls. ^18^F-dopa PET can detect frontal changes in Parkinson\'s
disease and preclinical disease in 30% of asymptomatic adult relatives
of familial cases. Single-photon-emission computed tomography (SPECT)
with ^123^iodobenzamide predicts dopaminergic responsiveness in patients
with Parkinsonism. More recently, it has been demonstrated that FDG-PET
performed at the time of initial referral for Parkinsonism accurately
predicted the clinical diagnosis of individual patients made at
subsequent follow-up.

*Multiple System Atrophy*

The discovery in 1989 of glial cytoplasmic inclusions (GCI) in the brain
of patients with multiple system atrophy (MSA) provided a pathological
marker for the disorder and confirmed that SND, OPCA, and Shy- Drager
syndrome are the same disease with different clinical expression.
Criteria for diagnosing MSA have been defined by a multidisciplinary
panel. MSA can present with autonomic or motor deficits. The predominant
motor deficit can be cerebellar (MSA-C = olivopontocerebellar atrophy)
or parkinsonism (MSA-P = striatonigral degeneration). MSA-P is
characterized clinically by Parkinsonian symptoms with prominence of
rigidity and with an absent or poor response to anti-Parkinson
medication.

Neuroimaging and gross pathology show atrophy of the striatum due to
neuronal loss, with the putamen more involved than the caudate. At 1.5T,
long-TR, long-TE images show putaminal hypointensity, particularly along
its posterolateral margin, equal to or more evident than pallidal
hypointensity. The degree of hypointense signal correlates significantly
with the severity of rigidity. The hypointense signal is due to the
paramagnetic effect of iron. PET with ^18^F-dopa is useful in
differentiating between PD and MSA.

More recently, hypointense putaminal signal changes on T2\* sequences
have been described in MSA more often than in PD but not on T2-weighted
images. These discrepancies between the results of recent studies and
previous results are probably due to the evolution of MRI sequences
currently employed. Fast spin-echo (SE) sequences are far less sensitive
to magnetic susceptibility than SE T2-weighted sequences used in 1986.
In a recent study of 230 Japanese patients with MSA, a hyperintense rim
at the lateral edge of the dorsolateral putamen was seen on MRI in 34.5%
of cases, and a \"hot cross bun\" sign in the pontine basis (PB) in
63.3%. These putaminal and pontine abnormalities became more prominent
as MSA-P and MSA-C features advanced.

*Progressive Supranuclear Palsy*

Progressive supranuclear palsy (PSP), also called Steele-
Richardson-Olszewski syndrome, is one of the most common atypical
Parkinsonian syndromes. To improve the specificity and sensitivity of
the clinical diagnosis of PSP, the NINDS and the Society for PSP have
developed a set of diagnostic criteria for this disorder. There are
three degrees of diagnostic certainty: possible, probable, and definite.
Possible PSP requires a gradually progressive disorder with onset at age
40 or later, either vertical supranuclear gaze palsy or both slowing of
vertical saccades and prominent postural instability with falls in the
first year of onset. Probable PSP requires vertical supranuclear gaze
palsy, prominent postural instability, and falls in the first year of
onset.

Putaminal hypointensity has been described in PSP patients at 1.5T,
using long-TR and long-TE sequences. The periaqueductal region of the
midbrain is also implicated in the pathology of PSP. Some patients show
slight hyperintense signal on the long-TR sequences of the
periaqueductal gray matter. It has been shown that anteroposterior
diameters of the suprapontine midbrain measured on axial T2-weighted MRI
in patients with PSP were significantly lower than those of patients
with PD and in control subjects without any overlap between these two
groups. Other authors have demonstrated that the average midbrain area
of patients with PSP measured on midsagittal MRI was significantly
smaller than that of the patients with PD and MSA-P and that of an
agematched control group.

**Degenerative Diseases of the Motor System**

Motor neuron diseases are a heterogeneous group of syndromes in which
the upper and/or lower motor neurons degenerate. Amyotrophic lateral
sclerosis (ALS) is the most frequent type of motor neuron disease, with
an annual incidence rate of 0.4 to 1.76 per 100,000 people. Most
patients are 50 years of age or older at the onset of symptoms. The
disorder progresses relentlessly; about half the patients are dead
within 3 years and 90% within 6 years.

ALS is characterized predominantly by degeneration of the corticospinal
tract and lower motor neurons. The extent of corticospinal tract
degeneration varies along the neuraxis. It can usually be traced from
the lower portion of the spinal cord up through the medulla.
Occasionally, degeneration of motor fibers proceeds farther cephalad
sequentially through the pyramidal tracts of the brainstem and cerebral
peduncles, the posterior part of the posterior limb of the internal
capsule, and corona radiata, to the motor cortex. On MRI, atrophy and
hyperintense foci of the corticospinal tract is seen on long-TR
sequences. This high signal likely reflects characteristic histologic
changes of myelin loss and gliosis. Hypointense signal on long-TR and
long-TE sequences may also be found in ALS, due to iron deposition. The
anterior and lateral portions of the cord may be atrophic and flattened
due to loss of motor neurons in the anterior horns and corticospinal
tracts. Magnetization transfer measurements are useful for detecting
abnormalities associated with degeneration of the pyramidal tract in
patients with ALS.

Proton magnetic resonance spectroscopy reveals decreased N-acetyl
aspartate values in the sensorimotor cortex and brainstem of patients
with ALS, consistent with neuronal dysfunction or loss. Involvement of
the corticospinal tract in patients with ALS has been demonstrated using
diffusion tensor imaging even at an early stage.

**Anticipated Exceptions**

Nephrogenic systemic fibrosis (NSF, also known as nephrogenic fibrosing
dermopathy) was first identified in 1997 and has recently generated
substantial concern among radiologists, referring doctors and lay
people. Until the last few years, gadolinium-based MR contrast agents
were widely believed to be almost universally well tolerated, extremely
safe and non-nephrotoxic, even when used in patients with impaired renal
function. All available experience suggests that these agents remain
generally very safe, but recently some patients with renal failure who
have been exposed to gadolinium contrast agents (the percentage is
unclear) have developed NSF, a syndrome that can be fatal. Further
studies are necessary to determine what the exact relationships are
between gadolinium-containing contrast agents, their specific components
and stoichiometry, patient renal function and NSF. Current theory links
the development of NSF to the administration of relatively high doses
(e.g., \>0.2 mM/kg) and to agents in which the gadolinium is least
strongly chelated. The FDA has recently issued a \"black box\" warning
concerning these contrast agents
(<http://www.fda.gov/cder/drug/InfoSheets/HCP/gcca_200705HCP.pdf>).

This warning recommends that, until further information is available,
gadolinium contrast agents should not be administered to patients with
either acute or significant chronic kidney disease (estimated GFR \<30
mL/min/1.73m^2^), recent liver or kidney transplant or hepato-renal
syndrome, unless a risk-benefit assessment suggests that the benefit of
administration in the particular patient clearly outweighs the potential
risk(s).

**Abbreviations**

-   CT, computed tomography

-   CTA, computed tomography angiography

-   FDG-PET, fluorodeoxyglucose positron emission tomography

-   fMRI, functional magnetic resonance imaging

-   MRI, magnetic resonance imaging

-   MRA, magnetic resonance angiography

-   MRI, magnetic resonance imaging

-   NUC, nuclear medicine

-   SPECT, single photon emission computed tomography

-   US, ultrasound

#### CLINICAL ALGORITHM(S)

None provided

### EVIDENCE SUPPORTING THE RECOMMENDATIONS

#### TYPE OF EVIDENCE SUPPORTING THE RECOMMENDATIONS

The recommendations are based on analysis of the current literature and
expert panel consensus.

### BENEFITS/HARMS OF IMPLEMENTING THE GUIDELINE RECOMMENDATIONS

#### POTENTIAL BENEFITS

Selection of appropriate radiologic imaging procedures for dementia and
movement disorders

#### POTENTIAL HARMS

-   The relative radiation level is high for fluorodeoxyglucose positron
    emission tomography (FDG-PET) of the head and nuclear medicine (NUC)
    single photon emission computed tomography (SPECT) of the head; and
    low for computed tomography (CT) of the head without contrast, CT of
    the head with and without contrast, computed tomography angiography
    (CTA) of the head and or neck, and NUC cisternography.

-   Some patients with renal failure who have been exposed to gadolinium
    contrast agents (the percentage is unclear) have developed
    nephrogenic systemic fibrosis, a syndrome that can be fatal. Until
    further information is available, gadolinium contrast agents should
    not be administered to patients with either acute or significant
    chronic kidney disease (estimated GFR \<30 mL/min/1.73m^2^), recent
    liver or kidney transplant or hepato-renal syndrome, unless a
    risk-benefit assessment suggests that the benefit of administration
    in the particular patient clearly outweighs the potential risk(s).

### QUALIFYING STATEMENTS

#### QUALIFYING STATEMENTS

An American College of Radiology (ACR) Committee on Appropriateness
Criteria and its expert panels have developed criteria for determining
appropriate imaging examinations for diagnosis and treatment of
specified medical condition(s). These criteria are intended to guide
radiologists, radiation oncologists and referring physicians in making
decisions regarding radiologic imaging and treatment. Generally, the
complexity and severity of a patient\'s clinical condition should
dictate the selection of appropriate imaging procedures or treatments.
Only those exams generally used for evaluation of the patient\'s
condition are ranked. Other imaging studies necessary to evaluate other
co-existent diseases or other medical consequences of this condition are
not considered in this document. The availability of equipment or
personnel may influence the selection of appropriate imaging procedures
or treatments. Imaging techniques classified as investigational by the
U.S. Food and Drug Administration (FDA) have not been considered in
developing these criteria; however, study of new equipment and
applications should be encouraged. The ultimate decision regarding the
appropriateness of any specific radiologic examination or treatment must
be made by the referring physician and radiologist in light of all the
circumstances presented in an individual examination.

### IMPLEMENTATION OF THE GUIDELINE

#### DESCRIPTION OF IMPLEMENTATION STRATEGY

An implementation strategy was not provided.

#### IMPLEMENTATION TOOLS

Personal Digital Assistant (PDA) Downloads

For information about
[availability](#identifying-information-and-availability), see the
\"Availability of Companion Documents\" and \"Patient Resources\" fields
below.

### INSTITUTE OF MEDICINE (IOM) NATIONAL HEALTHCARE QUALITY REPORT CATEGORIES

#### IOM CARE NEED

Getting Better\
Living with Illness

#### IOM DOMAIN

Effectiveness

### IDENTIFYING INFORMATION AND AVAILABILITY

#### BIBLIOGRAPHIC SOURCE(S)

Dormont D, Seidenwurm DJ, Davis PC, Brunberg JA, De La Paz RL, Hackney
DB, Jordan JE, Karis JP, Mukherji SK, Turski PA, Wippold FJ II,
Zimmerman RD, McDermott MW, Sloan MA, Expert Panel on Neurologic
Imaging. Dementia and movement disorders. \[online publication\]. Reston
(VA): American College of Radiology (ACR); 2007. 15 p. \[86 references\]

#### ADAPTATION

Not applicable: The guideline was not adapted from another source.

#### DATE RELEASED

1996 (revised 2007)

#### GUIDELINE DEVELOPER(S)

American College of Radiology - Medical Specialty Society

#### SOURCE(S) OF FUNDING

The American College of Radiology (ACR) provided the funding and the
resources for these ACR Appropriateness Criteria®.

#### GUIDELINE COMMITTEE

Committee on Appropriateness Criteria, Expert Panel on Neurologic
Imaging

#### COMPOSITION OF GROUP THAT AUTHORED THE GUIDELINE

*Panel Members*: Didier Dormont MD; David J. Seidenwurm, MD; Patricia C.
Davis, MD; James A. Brunberg, MD; Robert Louis De La Paz, MD; David B.
Hackney, MD; John E. Jordan, MD; John P. Karis, MD; Suresh Kumar
Mukherji, MD; Patrick A. Turski, MD; Franz J. Wippold II, MD; Robert D.
Zimmerman, MD; Michael W. McDermott, MD; Michael A. Sloan, MD, MS

#### FINANCIAL DISCLOSURES/CONFLICTS OF INTEREST

Not stated

#### GUIDELINE STATUS

This is the current release of the guideline.

This guideline updates a previous version: Braffman B, Drayer BP,
Anderson RE, Davis PC, Deck MD, Hasso AN, Johnson BA, Masaryk T,
Pomeranz SJ, Seidenwurm D, Tanenbaum L, Masdeu JC. Dementia. American
College of Radiology. ACR Appropriateness Criteria. Radiology 2000
Jun;215(Suppl):525-33. \[31 references\]

The appropriateness criteria are reviewed annually and updated by the
panels as needed, depending on introduction of new and highly
significant scientific evidence.

#### GUIDELINE AVAILABILITY

Electronic copies: Available in Portable Document Format (PDF) from the
[American College of Radiology (ACR) Web
site.](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/pdf/ExpertPanelonNeurologicImaging/NeurodegenerativeDisordersUpdateinProgressDoc9.aspx)

ACR Appropriateness Criteria® *Anytime*, *Anywhere*™ (PDA application).
Available from the [ACR Web
site](http://www.acr.org/SecondaryMainMenuCategories/ACRStore/FeaturedCategories/QualityandSafety/ac_pda.aspx).

Print copies: Available from the American College of Radiology, 1891
Preston White Drive, Reston, VA 20191. Telephone: (703) 648-8900.

#### AVAILABILITY OF COMPANION DOCUMENTS

The following are available:

-   ACR Appropriateness Criteria®. Background and development. Reston
    (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria.aspx).

-   ACR Appropriateness Criteria®. Relative radiation level information.
    Reston (VA): American College of Radiology; 2 p. Electronic copies:
    Available in Portable Document Format (PDF) from the [American
    College of Radiology (ACR) Web
    site](http://www.acr.org/SecondaryMainMenuCategories/quality_safety/app_criteria/RRLInformation.aspx).

#### PATIENT RESOURCES

None available

#### NGC STATUS

This summary was completed by ECRI on July 31, 2001. The information was
verified by the guideline developer as of August 24, 2001. This NGC
summary was updated by ECRI Institute on December 21, 2008.

#### COPYRIGHT STATEMENT

Instructions for downloading, use, and reproduction of the American
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© 1998-2008 National Guideline Clearinghouse

Date Modified: 11/3/2008