bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion MRI: Precision, accuracy and flow effects
Authors: Conturo Thomas E. , McKinstry Robert C. , Aronovitz Joseph A. , Neil Jeffrey J. 
Published: March 2007

AbstractAfter a decade of evolution and application of diffusion imaging, a large body of literature has been accumulated. It is in this context that the accuracy and precision of diffusion‐weighted and quantitative diffusion MRI are reviewed. The emphasis of the review is on practical methods for clinical human imaging, particularly in the brain. The requirements for accuracy and precision are reviewed for various clinical and basic science applications. The methods of measuring and calculating diffusion effects with MRI are reviewed. The pulse gradient spin echo (PGSE) methods are emphasized as these methods are used most commonly in the clinical setting. Processing of PGSE data is reviewed. Various PGSE encoding schemes are also reviewed in terms of the accuracy and precision of isotropic and anisotropic diffusion measurements. The broad range of factors impacting the accuracy of the PGSE methods and other encoding schemes is then considered. Firstly, system inaccuracies such as background imaging gradients, gradient linearity, refocusing RF pulses, eddy currents, image misregistration, noise and dynamic range are considered. A second class of inaccuracies is contributed by the bulk effects of the imaged object, and include sample background gradients, subject motion of cerebrospinal fluid and organs, and aperiodic organ motion. A final category of potential inaccuracies is classified as being contributed by microscopic, biophysical tissue properties and include partial volume effects, anisotropy, restriction, diffusion distance, compartmentation, exchange, multiexponential diffusion decay, T2 weighting and microvascular perfusion. Finally, the application of diffusion methods to studies of blood flow in the microvasculature (i.e. the arterioles, capillaries and venules) are reviewed in detail, particularly in terms of feasibility and the stringent accuracy and precision requirements. Recent provocative studies examining the use of PGSE approaches to suppress microvascular signals in brain functional MRI (fMRI) are also reviewed.
Inferring microstructural features and the physiological state of tissues from diffusion‐weighted images
Authors: Basser Peter J. 
Published: March 2007

AbstractWe review several methods that have been developed to infer microstructural and physiological information about isotropic and anisotropic tissues from diffusion weighted images (DWIs). These include Diffusion Imaging (DI), Diffusion Tensor Imaging (DTI), isotropically weighted imaging, and q‐space imaging. Just as DI provides useful information about molecular displacements in one dimension with which to characterize diffusion in isotropic tissues, DTI provides information about molecular displacements in three dimensions needed to characterize diffusion is anisotropic tissues. DTI also furnishes scalar parameters that behave like quantitative histological or physiological‘stains’ for different features of diffusion. These include Trace(D), which is related to the mean diffusivity, and a family of parameters derived from the diffusion tensor, D, which characterize different features of anisotropic diffusion. Simple thought experiments and geometrical constructs, such as the diffusion ellipsoid, can be used to understand water diffusion in isotropic and anisotropic media, and the NMR experiments used to characterize it.
Diffusion‐weighted NMR imaging: Application to experimental focal cerebral ischemia
Authors: Hoehn‐Berlage Mathias 
Published: March 2007

AbstractChanges in diffusion NMR imaging are believed to be based on intra/extracellular water homeostasis and will therefore reflect early disturbances of ion and water homeostasis after the onset of an ischemic event. Diffusion‐weighted NMR imaging (DWI) thus has the potential to be a sensitive tool for the observation of stroke evolution. The present state of information extracted from diffusion‐weighted NMR imaging for the understanding of cerebral focal ischemia in experimental research has been compiled in this review. The emphasis was set on three essential aspects of the technique in relation to focal ischemia. Firstly, the sensitivity of diffusion‐weighted imaging for ischemic alterations is described. A comparison with conventional NMR imaging using relaxation time changes is included. Secondly, the comparison of the diffusion‐weighted imaging with invasive techniques is discussed. Here, interpretation of the physiological, metabolic and hemodynamic alterations reflected in the observed diffusion changes is presented. The importance of regionally resolved information for a meaningful assignment of DWI changes to pathophysiological alterations is demonstrated for the differentiation between ischemic core and penumbra from DWI and quantitative diffusion coefficient data. The time dependence of correlations with physiological, biochemical and hemodynamic variables as a further important aspect is stressed. Thirdly, the potential of the technique for the assessment of development and effectiveness of new therapeutical strategies against stroke is demonstrated.
Diffusion‐weighted NMR imaging changes caused by electrical activation of the brain
Authors: Prichard James W. , Zhong Jianhui , Petroff Ognen A. C. , Gore John C. 
Published: March 2007

AbstractThe apparent diffusion coefficient of brain water was decreased by frontal cortical electroshock, usually but not always associated with brief epileptic afterdischarge detectable at the parietal cortex. Previous studies have shown that status epilepticus causes similar larger decreases, which are largely reversible by the termination of seizure discharge with pentobarbital. Cerebral blood flow is elevated in these conditions, and biochemical energy failure does not occur. The brain water diffusion coefficient also decreases in spreading depression, without depletion of energy stores. All of these findings may be due in part to the reduction of brain extracellular space caused by cell swelling, which occurs to some degree in all three conditions. However, major biological differences between brain activation and brain ischemia and new evidence for increased cytosolic viscosity in the latter both suggest that other mechanisms deserve further investigation. Use‐dependent motility of dendritic spines and other phenomena that may allow direct detection of neural activity by diffusion‐weighted NMR imaging are of special interest.
In vivo diffusion spectroscopy. An overview
Authors: Nicolay Klaas , Toorn Annette Van Der , Dijkhuizen Rick M. 
Published: March 2007

AbstractThis review describes in vivo NMR measurements of metabolite diffusion. NMR spectroscopy can employ a variety of endogeneous marker molecules to obtain information on various aspects of in vivo biochemistry and biophysics from the diffusion characteristics of these markers. NMR‐based metabolite diffusion data give an insight into the physico‐chemical properties of the intracellular compartment and of changes therein in relation to development and pathology. Recent applications have proven that in vivo diffusion spectroscopy provides exciting opportunities to both fundamental and applied research.
Clinical Aspects of DWI
Authors: Moseley Michael E. , Butts Kim , Yenari Midori A. , Marks Michael , Crespigny Alex De 
Published: March 2007

AbstractDiffusion‐weighted MR imaging (DWI) is capable of imaging ischemia‐induced changes in water protons in either animal or man. Technical developments are described that allow the routine clinical utility of DWI in a stroke setting to provide objective criteria beyond the neurological exam by which the pathophysiology of stroke can be evaluated. To date, DWI has provided unique information concerning detection and evaluation of acute, symptomatic lesions from older, chronic strokes, detection and localization of small deep infarcts and reversible ischemic neurologic deficits and transient ischemia. Clinical DWI studies suggest that the temporal behaviour of ADC can critically improve the evaluation of clinical ischemia.
The prenatal diagnosis of the Walker‐Warburg Syndrome
Authors: Crowe Carol , Jassani Majida , Dickerman Lois 
Published: March 2007

AbstractOn the basis of physical features and autopsy findings, a child with congenital hydrocephalus, bilateral microphthalmia, myopathy, severe developmental retardation and multiple brain malformations was diagnosed to have the Walker‐Warburg Syndrome (WWS). During a subsequent pregnancy in this family, a fetus at risk for this autosomal recessive condition was evaluated with serial ultrasound examinations. At 15 weeks of gestation an encephalo‐cele was noted. Disproportionately slow growth of the head compared to the body was noted at 36 weeks. At birth, the diagnosis of WWS was confirmed in the child due to the presence of microcephaly, an encephalocele, a meningocele and bilateral microphthalmia. This is the first reported case of the early prenatal diagnosis of this recently categorized genetic condition, in which the major features are hydrocephalus, multiple central nervous system malformations, microphthalmia with ocular malformations, severe psychomotor retardation, congenital myopathy and a very limited life expectancy.
Prenatal diagnosis of hunter syndrome using chorionic villi
Authors: Pannone N. , Gatti R. , Lombardo C. , Di Natale P. 
Published: March 2007

AbstractA case of the Hunter syndrome diagnosed prenatally using chorionic villi is presented. Chorion biopsy was performed in the 10th week of pregnancy. The sample was examined for karyotype and for iduronate sulfatase activity. The fetus was male and the enzyme activity reduced to 4 per cent of normal. Termination of pregnancy occurred at the 11th week.
Prenatal diagnosis of a de novo complex chromosomal rearrangement involving four chromosomes
Authors: Kim Hyon Ju , Perle Mary Ann , Bogosian Virginia , Greco Alba 
Published: March 2007

AbstractA complex chromosome rearrangement, apparently a balanced translocation involving chromosomes 4,6, 15 and 16, was found in cultured cells of amniotic fluid from a 32–year‐old primigravida who requested amniocentesis for prenatal diagnosis because of a family history of mental retardation. Chromosome analysis of peripheral blood from both parents were normal.The couple was counselled for the prenatal diagnosis of this de novo complex translocation and, subsequently, elected to terminate the pregnancy. Post‐mortem examination revealed a 23–week fetus with intrauterine growth retardation. The identical chromosome rearrangement was subsequently confirmed in cultured fibroblasts from skin and cord obtained from the abortus.To our knowledge, this is the first report where routine prenatal diagnosis revealed a fetus with a balanced complex chromosomal rearrangement involving four chromosomes of de novo origin.
Congenital chylothorax‐prenatal ultrasonic diagnosis and successful post partum management
Authors: Meizner I. , Carmi R. , Bar‐Ziv J. 
Published: March 2007

AbstractThe prenatal diagnosis by ultrasound of congenital chylothorax is described allowing early intervention immediately after delivery. Unilateral fluid collection in the right lung with marked displacement of the heart to the left were the most prominent sonographic signs. Post partum thoracocentesis and chylus fluid drainage served as a life saving procedure.
Prenatal diagnosis of zellweger's syndrome by chorionic villus sampling‐and a caveat
Authors: Carey W. F. , Robertson E. F. , Van Crugten C. , Poulos A. , Nelson P. V. , Finikiotis G. 
Published: March 2007

AbstractAt 7·5 weeks gestation, two small chorionic villous biopsies were obtained from a woman at risk for Zellweger's cerebro‐hepato‐renal syndrome, and were separately established in culture. After 3 weeks, dihydroxyacetone phosphate acyltransferase (DHAP‐AT) activity was measured in both cultures. The enzyme was markedly deficient in one cell strain and this was subsequently shown to have a male karyotype. However, the second culture had normal enzyme activity and a female karyotype.The pregnancy was terminated at 11·5 weeks gestation, and follow‐up studies on fetal tissues confirmed a male fetus with markedly deficient DHAP‐AT activity.
Maternal age and amniocentesis: Should this be lowered to 30 years?
Authors: Crandall B. F. , Lebherz T. B. , Tabsh K. 
Published: March 2007

AbstractWe have reviewed the results of 10000 2nd trimester amniocenteses performed at our centre. Over 80 per cent of these were done only because of maternal age (MA); there were three times as many < 35 year‐old women in 1984 compared to 1975. Of women aged 30–34 years at delivery 0·69 per cent were found to have a MA‐related chromosome abnormality compared to 0·94 per cent in those aged 35–40 years. Because only about 7 per cent of births occurred to women ⩾ 35 years and 18·6 per cent between 30–34 years, and a practical utilization rate of 50 per cent, we recommend that amniocentesis be made available to women aged ⩾ 30 years. We believe that 27 per cent of Down syndrome (DS) pregnancies could be identified if 50 per cent of pregnant women in this age category availed themselves of the test. With the same utilization rate, about three times as many amniocenteses would be required in California as performed here in 1983.
Chorionic villus culture for first trimester diagnosis of chromosome defects: Evaluation by two london centres
Authors: Czepulkowski B. H. , Heaton D. E. , Kearney L. U. , Rodeck C. H. , Coleman D. V. 
Published: March 2007

AbstractThe maceration technique for the culture of chorionic villi has been applied by St Mary's Hospital and King's College Hospital, to a total of 225 villus aspirates of which 100 were from diagnostic cases. Two hundred and eighteen (96·8 per cent) of these were successfully karyotyped, and chromosome abnormalities were detected in 15 cases. Of the cases with a normal karyotype, 113 were male and 90 were female. Sixty‐nine (77 per cent) of the female cultures were demonstrated to be fetal and a further two of these may be verified at delivery. The use of Chang medium was found to accelerate cell growth thereby reducing the interval between sampling and reporting to less than 2 weeks. An unlimited quantity of metaphase spreads was obtained suitable for the application of routine banding techniques, and comparable to those obtained from amniotic fluid culture. Experience with diagnostic cases reinforced our view that culture should always back up direct analysis and this is discussed with particular reference to the occurrence of mosaicism in the trophoblast.
Short communication kazal type trypsin inhibitor in amniotic fluid in fetal developmental disorders
Authors: Kolho K. L. 
Published: March 2007

AbstractThe amniotic fluid concentrations of the Kazal type trypsin inhibitor were studied in pregnancies with fetal developmental disorders. The samples were obtained by amniocentesis between 14 and 19 weeks of gestation. In cases with fetal malformations, the level was below the normal 10th centile in 15 out of 28 cases (54 per cent, P<0.05) and above the normal 90th centile in 2 cases (7.1 per cent). Low values were common in cases with intrauterine fetal death or congenital nephrosis. The levels were normal in fetal chromosomal aberrations.
Inv dup (15): Prenatal diagnosis and postnatal follow‐up
Authors: Miny P. , Basaran S. , Kuwertz E. , Holzgreve W. , Pawlowitzki I.‐H. 
Published: March 2007

AbstractA de novo inv dup (15) was diagnosed at amniocentesis. No physical abnormalities were detected after birth. The boy developed severe mental and motor retardation, which became obvious at 16 months of age.
Prenatal diagnosis of osteogenesis imperfecta type III
Authors: Robinson L. Pat , Worthen Nancy J. , Lachman Ralph S. , Adomian Gerald E. , Rimoin David L. 
Published: March 2007

AbstractUltrasonographic and radiographic evaluation of a fetus at risk for osteogenesis imperfecta (O.I) type III was performed. Real‐time ultrasound measurements at 15 weeks gestation were interpreted as normal, but at 20 and 22 weeks of gestation revealed marked shortening of the long bones and deformity of the femurs. The findings were confirmed by fetal radiography at 22 weeks gestation. Radiographic and histologic changes characteristic of O.I. were observed in the aborted fetus. Thus the antenatal manifestations of O.I. type III maybe severe enough to make prenatal diagnosis possible in the second trimester for families at risk for recurrence of this disorder.
First trimester diagnosis of RhO (D) with an immunofluorescence technique after chorionic villus sampling
Authors: Fuhrman H. C. , Klink F. , Grzejszczyk G. , Vossberg A. , Poschmann A. , Geusendam G. , Froster‐Iskenius U. , Schwinger E. 
Published: March 2007

AbstractDouble indirect immunofluorescence technique (DIIF) was applied to fetal erythrocytes from vascularized chorionic villi, obtained by chorionic villus sampling (CVS) in the first trimester of pregnancy, to determine the presence of Rhesus antigen Rh (D).
Prenatal diagnosis of severe combined immunodeficiency with defective synthesis of HLA molecules
Authors: Durandy A. , Cerf‐Bensussan N. , Dumez Y. , Griscelli C. 
Published: March 2007

AbstractThe immunodeficiency associated with a defective expression of HLA molecules is an autosomal recessive disorder leading to death during childhood. We have performed prenatal diagnosis for six fetuses at risk for this disease by membrane immunofluorescence on blood lymphocytes and monocytes, using specific monoclonal antibodies for HLA class I and II molecules. Two pregnancies have been found to be affected. The diagnosis has been confirmed on each abortus by the study of the membrane expression of HLA class I and II molecules on blood lymphocytes and monocytes, and on thymic and splenic cells. The four other cases were found to be normal both during pregnancy and after birth. The detection of the defect as early as the 20th week of gestation allows selective termination.
Temporal changes in Ohio amniocentesis utilization during the first twelve years (1972–1983), and frequency of chromosome abnormalities observed
Authors: Naber John M. , Huether Carl A. , Goodwin Beth A. 
Published: March 2007

AbstractThe history of amniocentesis utilization in the seventh largest state of the United States is documented from its inception in 1972 through the first half of 1984. Amniocentesis utilization ratios for Ohio residents aged ⩾35 have increased from 0.21 per cent (19/9091) in 1972 to 23.4 per cent (1655/7531) in 1983, representing an average annual growth rate of 43.1 per cent. Of the amniocenteses performed from January 1, 1978–July 1, 1984, 71 per cent were referred for advanced maternal age (⩾35), 15 per cent for maternal anxiety (30–34), 10 per cent for family history or previous child with a genetic defect, and 4 per cent for other reasons. Between 1978‐1983 utilization by women 45 years of age was only 20 per cent higher than women 35 even though their risk of giving birth to a Down syndrome child was about one order of magnitude higher. In addition, various factors were tested as to whether they affected utilization of amniocentesis by women ⩾35 during 1978 1983. A strong correlation of +0.89 existed between county population size and utilization ratios. No difference in utilization was found between whites and nonwhites, regardless of county population size. When utilization ratios were compared separately between Protestants, Catholics and other religions in Ohio's most populated county, no statistical differences were found. From 1978–July 1, 1984, the frequency of all cytogenetically abnormal chromosome results observed in Ohio amniocenteses to women ⩾35 was 2.48 per cent (187/7536). Of these, 2.15 per cent (162/7536) had unbalanced karyotypes. Future maximum amniocentesis utilization for women ⩾35 is estimated at 60–70 per cent.
Prenatal diagnosis of mosaic trisomy 9
Authors: Zadeh Touran M. , Peters June , Sandlin Constance 
Published: March 2007

AbstractMosaic trisomy 9 was detected in an amniotic fluid cell culture from a 40‐year‐old woman evaluated because of advanced maternal age. After counselling, parents elected to terminate the pregnancy. On autopsy the fetus was found to have hydrocephalus and a single kidney. The diagnosis of trisomy 9 mosaicism was confirmed in cultured skin fibroblasts. This is the third reported case of trisomy 9 mosaicism diagnosed prenatally.
Determination of maternal serum acetylcholinesterase in pregnancies with fetal neural tube defects
Authors: Sorensen K. , Brodbeck U. , Rasmussen A. G. , Norgaard‐Pedersen B. 
Published: March 2007

AbstractWe have investigated the occurrence of acetylcholinesterase (AChE) (E.C.3.1.1.7) in fetal serum, amniotic fluid and maternal serum using an immuno‐chemical assay‐technique employing both polyclonal and monoclonal antibodies. Fetal serum had increased amounts of AChE, which is due to an increase in the 10.5S form of the enzyme. This form was also found in amniotic fluids of pregnancies with a fetal neural tube defect (NTD), but not in normal amniotic fluid. The increase in amniotic fluid AChE was however, not reflected in the maternal serum.
The impact of screening for open neural tube defects in England and Wales
Authors: Cuckle Howard , Wald Nicholas 
Published: March 2007

AbstractUsing information derived from the voluntary system of notification of congenital malformations in England and Wales, the birth prevalence of anencephaly and spina bifida was estimated to have declined by 80 per cent from 31.5 to 6.2 per 10 000 between 1964–1972 and 1985. Over the same period, notified terminations of pregnancy with a suspected fetal central nervous system abnormality increased from less than 1 per cent to 56 per cent of neural tube defect births and central nervous system terminations combined, accounting for 31 per cent of the decline in births. Routinely collected national statistics provide a method for monitoring the impact of screening for open neural tube defects. However because they are incomplete and lack detail an alternative method of monitoring is needed. This paper includes an outline of such a method, together with the results of a pilot study designed to assess the feasibility of monitoring screening in the Oxford Region.
Prenatal diagnosis of alpha‐1‐antitrypsin deficiency by fetal blood sampling
Authors: Corney G. , Whitehouse D. B. , Hopkinson D. A. , Rodeck C. H. , Nicolaides K. , Norman M. , Mowat A. P. 
Published: March 2007

AbstractFetal blood sampling for the diagnosis of alpha‐1‐antitrypsin deficiency using protein isoelectric focusing was carried out in the period 1980–1985. The results of 25 cases from 18 mothers are reported. All had a previous history of a PiZ child affected by liver disease.The method was found to be technically satisfactory and the fetal results were subsequently confirmed in all 18 cases where follow‐up was possible. The fetus was found to be PiZ in nine cases and all these pregnancies were terminated. Of the remaining pregnancies three cases aborted or were delivered prematurely and 13 proceeded to term without complications.
Prenatal diagnosis and obstetrical management of multicystic dysplastic kidney disease
Authors: Rizzo Nicola , Gabrielli Sandro , Pilu Gianluigi , Perolo Antonella , Cacciari Alfredo , Domini Remigio , Bovicelli Luciano 
Published: March 2007

AbstractMulticystic dysplastic kidney disease (MDKD) is one of the most common congenital renal anomalies. We report 16 consecutive cases of MDKD recognized in the antenatal period by sonography. Diagnosis is usually easy as MDKD has in the vast majority of cases a striking ultrasound appearance including enlargement of the kidney and multiple renal cysts. However, differentiation from obstructive uropathy may be difficult, and we made a total of five erroneous diagnoses. Unilateral MDKD has almost invariably a good prognosis. However, severe life‐threatening associated anomalies were found in six cases. Therefore, a detailed survey of fetal anatomy and determination of karyotype are strongly recommended.