bluuebunny/crossref_metadata_2025 huggingface dataset:
Duplex ultrasound, MR angiography and Conventional angiography in Carotid artery disease: interpretation of separate test results and their combinations.
Authors: Nederkoorn Paul J , Kappelle L Jaap , van der Graaf Yolanda , Hunink Myriam G , Eikelboom Bert C , Mali Willem P
Published: March 2022

107

Purpose:
To compare duplex ultrasound (DUS) and MR angiography (MRA) with conventional intra-arterial digital subtraction angiography (DSA) in patients with carotid artery disease.
Methods:
Between 1996 and 2000 375 consecutive patients with symptomatic carotid artery stenosis undergoing evaluation prior to endarterectomy were included. All patients with a peak systolic velocity (PSV) > 150 cm/sec measured on DUS subsequently underwent DSA and MRA. In the last phase of our study a subgroup of 40 patients additionally underwent contrast-enhanced MRA (CE-MRA). Standardized cutoff criterions based on PSV s were used to asses the degree of stenosis with DUS. The degree of stenosis on MRA was analyzed by means of the criteria used in the North American Endarterectomy Trial (NASCET). DSA served as the standard of reference.
Results:
DUS analyzed with standardized PSV criterions resulted in a sensitivity of 90% and a specificity of 83% in identifying severe ICA stenosis (70–99%). Stenosis measurements (NASCET) carried out on 3D-TOF MR angiograms yielded a sensitivity of 90% and a specificity of 84%. MRA had a tendency to overestimate the degree of stenosis compared with DSA. Combining MRA and DUS results, agreement between these two modalities (80% of carotids) gave a sensitivity of 98% and a specificity of 90%. In case of disagreement these numbers strongly decreased precluding meaningful diagnosis, MRA however performed slightly better than DUS did. Preliminary results of CE-MRA indicated good visibility, decrease of artifacts and accurate diagnostic performance.
Conclusions:
Both DUS and MRA seem accurate diagnostic tests to detect carotid artery stenosis using DSA as the standard of reference. MRA has the tendency to overestimate stenosis. Combining test results gives additional value in diagnostic outcome. Agreement between DUS and MRA results in higher sensitivity and specificity then disagreement between these modalities does. In case of disagreement MRA performs better then DUS, but DSA still seems recommendable. CE-MRA shows promising preliminary results.
Angiographic collaterals in acute stroke - relationship to clinical presentation and outcome: The PROACT II trial
Authors: Roberts Heidi C , Dillon William P , Furlan Anthony J , Rowley Howard A , Fischbein Nancy J , Higashida Randall T , Wechsler Lawrence R , Kase Carlos , Schulz Gregory A
Published: March 2022

113

We studied the relationship between angiographic collateral flow and stroke severity and outcome in patients with MCA occlusion. Patients (180) were randomized 2:1 to 9mg IA r-proUK + subtherapeutic IV heparin or IV heparin alone; 162 were treated as randomized. Angiography at baseline assessed vascular occlusion and collateral flow (no, partial, or complete supply of the ischemic territory). CT was obtained at baseline, 24hrs and 7–10days, and hypodensity volumes were measured. Clinical outcome was assessed at 90days (modified Rankin score≤2). At baseline, collateral flow in 161 cases was: 50 no supply, 100 partial, and 11 complete supply. Patients with complete supply had significantly smaller infarct volumes (2±1cc) on baseline CT than patients with some (13±2cc, p<0.05) or no collaterals (18±4cc, p<0.05). There was a statistically significant difference in the median baseline NIHSS score among the three collateral groups (15 complete vs.16.5 partial vs.18 no). There was no overall relationship between the extent of collaterals and outcome. When considering treatment groups, the effect of r-proUK appears to be (n.s.) greater with increasing degree of collaterals (Table). An analysis of the effect of collaterals and treatment groups on the evolution of hypodensity volumes on 24hrs- and 7–10day CTs was also performed. Collaterals appear to have an effect on baseline CT infarct volume and stroke severity, and on the effect of thrombolytic treatment.
Quantitative Measurements of Cerebral Metabolic Rate of Oxygen (CMRO2) Using MRI
Authors: Lin Weili , An Hongyu , Celik Azim , Lee Yueh
Published: March 2022

P10

Recently, we have demonstrated that a quantitative estimate of cerebral blood oxygen saturation can be obtained in vivo via blood oxygen level dependent contrast. With a ROI analysis, a mean cerebral blood oxygen saturation (CBOS) of 58.4% ± 1.8% was obtained from 8 normal healthy volunteers. When converting the MR measured CBOS to the oxygen extraction fraction (OEF) via the Hill equation as well as the oxygen dissociation curve, an MR-OEF of 42.6% was obtained, in excellent agreement with the known OEF under normal physiological conditions via PET. While it is known that the level of OEF is a strong indicator of the functional status of brain tissue, OEF by itself does not uniquely indicate brain ischemia or brain viability. Therefore, CMRO2, which includes both CBF and OEF, has been utilized to better characterize the balance between oxygen supply and demand in brain tissue. In order to obtain a quantitative estimate of MR-CMRO2, a measure of both OEF and CBF is required. In total, 5 normal healthy volunteers were studied. A 2D multiecho gradient/spin echo sequence was employed to acquire images, which were subsequently post-processed to obtain an estimate of MR-OEF. In addition, a dynamic imaging approach was utilized to acquire images before, during and after the injection of a paramagnetic contrast agent and post-processed via the singular value decomposition so that a quantitative estimate of CBF can be obtained. Finally, pixe-by-pixel MR-CMRO2 maps were calculated as the product of MR-OEF and MR-CBF. Four ROIs: one located in the cortical and one in the subcortical regions of each hemisphere, were defined to obtain measurements of MR-CMRO2 in all volunteers. A mean MR-CMRO2 of 27.7±6.2 ml/100gm/min and 10.5±3.2 ml/100gm/min was obtained for the cortical and subcortical regions, respectively. Notice the MR-CMRO2 differs from the conventionally measured CMRO2 via PET. No normalization with respect to the arterial oxygen content of each volunteer was made for the MR-CMRO2. With the non-invasive nature of MRI and the ability to provide quantitative estimates of cerebral oxygen metabolism in vivo, MR-CMRO2 should open a new avenue for the investigation of cerebrovascular disease.
Transcranial Doppler in Adults with Sickle Cell Disease
Authors: Adams Robert J , Kutlar Abdullah , Carl Elizabeth M , Daitch Lisa H , Bowman Latonya S , Nichols Fenwick T
Published: March 2022

P13

Transcranial Doppler(TCD)is of established use in primary stroke prevention in children with Sickle Cell Disease(SCD)but its value in adults with SCD is unproven. A pilot study to estimate prevalence of high velocity in adults and to correlate findings with those from children with SCD was performed. Thirty three patients with SCD over 18 year of age were studied with TCD using Nicolet TC-2000 during an outpatient visit. There were 3 patients with a remote history of stroke but none were on chronic transfusion. Twenty four(73%)were on hydroxyurea therapy. TCD was performed using the Stroke Prevention in Sickle Cell Disease(STOP)protocol: time averaged maximal mean(TAMM), systolic,and diastolic velocities were recorded for the left and right middle cerebral (MCA) and distal internal carotid artery (ICA). Classification as to normal (TAMM <170 cm/sec), conditional (TAMM 170–199), or abnormal (TAMM >200 cm/sec) was made using the STOP criteria. The mean age was 32 + 8 years (range 18–53). There were 13 men and 20 women. The results were: 19 normal (58%), 1 conditional (3%), 0 abnormal and 13 inadequate (39%). For those with adequate exams (n=21), the average highest TAMM on either side was 111 + 29 cm/sec. Two of four patients with a history of stroke had inadequate exams which may represent occluded vessels but the other two had normal exams. The results are at variance with those reported from children with SCD in that mean velocity is lower and the rate of inadequate exams is much higher(39 vs 5%). In 12 of 13 cases the reason for inadequate studies was no window on one or both sides rather than no MCA recorded. A typical sample of children with SCD would have included 8 cases with TAMM > 170 cm/sec instead of the single case observed in this study. Further study will be needed to determine if the apparent absence of high velocity in adults represents the effects of hydroxyurea, which increases hct by about 15%, is due to cases with unrecognized occlusion or severe stenosis which could also cause low velocity, or indicates that most patients with abnormal TCD as children either have stroke or resolve as they mature. The standards for abnormality based on the STOP study may have to be modified for adults.
Thalamic microstructural alterations secondary to white-matter damage in CADASIL: evidence from diffusion tensor imaging study
Authors: Chabriat Hugues , Molko Nicolas , Pappata Sabina , Mangin Jean Francois , Poupon Cyril , Jobert Antoinette , Le Bihan Denis , Bousser Marie-Germaine
Published: March 2022

P18

Background and Purpose:
Variable microstructural changes have been reported within the white-matter in CADASIL. Lacunar infarcts are frequently observed in the subcortical grey matter. However, whether microstructural tissular alterations are also present within the non-infarcted putamen (NIP) or thalamus (NIT), remains unknown.
Methods:
We used diffusion tensor imaging, a MRI method highly sensitive to the cerebral microstructure, in 20 CADASIL patients and 12 age-matched controls. Both Trace(D) and anisotropy (volume-ratio index) of diffusion were measured within the NIP and NIT. In addition, diffusion parameters and the load of small infarcts were calculated within the white-matter of the centrum semi-ovale. A one way ANOVA was performed to compare the diffusion parameters between patients and controls. Thereafter, correlations between the significant results in our patients and the diffusion parameters in the white-matter or the MMSE scores were tested.
Results:
A significant increase in Trace(D) and decrease in anisotropy were observed in both the NIP and NIT in our patients. Conversely to the results in the NIP, only significant in the presence of associated putaminal infarcts, the diffusion changes in the NIT were significant both in the presence and absence of associated thalamic infarcts. The asymmetry indices of Trace(D) in the NIT and in the white-matter were strongly correlated. The diffusion increase in the NIT was also positively correlated both to Trace(D) and to the load of small deep infarcts within the centrum semi-ovale. Elsewhere, the diffusion increase in the NIT, but not in the NIP, was negatively correlated to the MMSE score in our patients.
Conclusions:
These results suggest that microstructural alterations are present in both the NIP and NIT in CADASIL. In the NIT, microstructural alterations appear secondary to remote lesions of thalamo-cortical pathways. Diffusion measured in the NIT mirror both the degree of white-matter tissular damage and the clinical severity in CADASIL. This study highlights the importance of secondary neurodegeneration in a typical model of “pure vascular dementia”.
White Matter Abnormalities in Lacunar Stroke Patients
Authors: Benavente Oscar , Palacio Santiago , Kesava Prabhakar P , Bazan Carlos , Pearce Lesly
Published: March 2022

P22

Background
White matter abnormalities (WMA) on CT and MRI are commonly present in patients with cerebrovascular disease, especially in those with lacunar stroke. The underlying mechanism of WMA is still unclear, however an ischemic origin is postulated. Both lacunar stroke and WMA are mainly due to abnormalities of the small penetrating arteries.
Objective
To characterize the prevalence and severity of WMA in lacunar stroke patients and correlate them with vascular risk factors.
Patients and Methods
FLAIR MRI images of lacunar stroke patients in the NINDS funded Secondary Prevention of Small Subcortical Stroke (SPS3) pilot trial were included. Two neuroradiologists, blinded to clinical data, quantitated WMA using the European Task Force on Age Related White Matter Changes (ARWMC) and Fazekas scales.
Results
The first twenty-two patients entered in the study were included for this initial analysis: Mean age: 57 years, 50% females. The baseline characteristics and major vascular risk factors were similar in patients with mild WMA and in those with severe WMA (ARWMC 7+): mean age (59 vs 55 years) diabetes (64 vs 63%), hypertension (86 vs 88%) and smoking (71 vs 76%). Severity and distribution (periventricular and subcortical) of WMA showed similar distribution of risk factors. Severe WMA were more often present in Mexican-American patients (88 vs 46% p=0.09). Total number of lacunar infarcts correlated with severity of WMA (correlation coefficient 0.5, p=0.01).
Conclusions
Unexpectedly, severity of WMAs did not correlate with risk factors in these survivors of lacunar stroke, but did correlate with the number of lacunes. Our results support a common pathogenisis of lacunar infarcts and WMAs. These preliminary analyses will be extended as recruitment continues.
Diffusion and Perfusion MRI in Predicting Final Infarct Volume: A Study of 81 Patients with Acute Stroke
Authors: Schaefer Pamela W , He Julian , Hunter George , Hamberg Leena , Gonzalez Ramon G
Published: March 2022

P25

Purpose:
To assess the utility of diffusion weighted imaging, cerebral blood volume, cerebral blood flow and mean transit time mapping in predicting final infarct volume in 81 patients with acute ischemic stroke.
Methods:
DWI, CBV, CBF and MTT images were obtained in 81 patients within 53 hours of stroke onset. Follow-up CT or T2 weighted MR images were obtained at 1 day to 4 months. Ischemic region volumes were measured on all images. An analysis of covariance with the variables of age, sex, treatment, time from stroke onset to imaging, and lesion type was performed. Linear regressions of DWI, CBV, CBF and MTT versus final infarct volume were obtained. A mismatch was determined if there was greater than 20% difference in volume between the diffusion and perfusion images.
Results:
Analysis of covariance demonstrated that DWI best predicts final infarct volume and that CBV alone of the other variables significantly improves the DWI prediction of final infarct volume. Linear regression analysis yielded an R
2
of 0.90, slope of 1.24 for DWI versus follow-up, R
2
of 0.84, slope of 1.22 for CBV versus follow-up, R
2
of 0.37, slope of 0.44 for CBF versus follow-up and R
2
of 0.25, slope of 0.33 for MTT versus follow-up. 13/81 patients had a DWI - CBV mismatch with mean lesion growth of 121 % while 68/81 patients had a DWI - CBV match with mean lesion growth of 15%. 36/81 had a DWI - CBF mismatch with mean lesion growth of 56% while 45/81 had a DWI - CBF match with mean lesion growth of 13%. 43/81 had a DWI - MTT mismatch with mean lesion growth of 47%. 38/81 had a DWI - MTT match with mean lesion growth of 16%.
Conclusions:
Both DWI and CBV are very good predictors of final infarct volume. CBF and MTT maps identify tissue at risk of infarction not identified on DWI or CBV maps. Since this tissue does not always infarct, these maps greatly overestimate final infarct size.The identification of a DWI - CBV, DWI - CBF or DWI - MTT mismatch predicts much more lesion growth compared with a diffusion perfusion match. This is most dramatic for DWI - CBV mismatches. This information may be valuable in the assessment of new therapeutic strategies.
Carotid and Vertebral Artery Dissection: Elliptical Centric Contrast-enhanced MR Angiography
Authors: Huston John , Phan Thanh G , Brown Robert D , Bernstein Matt A , Riederer Stephen J , Fain Sean B
Published: March 2022

P30

Background and Purpose:
Contrast-enhanced MR angiography (CEMRA) has undergone considerable development in the past several years. Recently, a CEMRA technique was developed using elliptical centric view-ordering. The purpose of this study was to evaluate elliptical centric CEMRA of carotid and vertebral artery dissection.
Methods:
A retrospective review of CEMRAs in 422 consecutive patients was performed. MR angiography was performed using a volume neck coil or a dedicated neurovascular coil. The CEMRA utilized a 22 x 15 cm field of view (FOV) coronal slab, 44 sections, repetition time of 6.6 msec, echo time 1.4 msec, 45° flip angle, 256 x 168 (due to 3/4 phase FOV) matrix with a scan time of 54 seconds. The reconstruction used zero-filling in all three directions yielding 88 1.4 mm thick sections with 0.7 mm overlap and a 512 x 336 matrix. The actual voxel size was 0.76 (X) x 0.89 (Y) x 1.4 mm, yielding a voxel volume of 0.97 mm
3
before zero-filling. Zero-filling improved resolution and yielded an effective voxel volume of approximately 0.35 mm
3
. Triggering of the CEMRA was performed with MR fluoroscopy or following a timing sequence. 20–25 cc of gadolinium was injected with a power injector at a rate of 3 cc per second followed by 30 cc of saline at a rate of 2 cc per second.
Results:
Of the 422 patients, 239 had acute or recent symptoms of TIA or ischemic stroke. Of this group, 32 patients had a carotid artery (22) or a vertebral artery (10) dissection. Eleven patients had a pseudoaneurysm detected at the site of the dissection. Recanalization of a previously occluded artery and a resolution of a pseudoaneurysm were demonstrated in one patient, respectively. In one patient, the CEMRA appeared normal, however, a subtle irregularity consistent with a vertebral artery dissection was demonstrated on a conventional angiogram two days following the MR angiogram.
Conclusions:
Contrast-enhanced elliptical centric MR angiography offers high resolution, venous-suppressed images of the carotid and vertebral arteries. This technique offers promise for noninvasive evaluation and follow-up of carotid and vertebral artery dissections.
Severe ADC Decreases Do Not Predict Irreversible Tissue Damage In Acute Human Stroke
Authors: Fiehler Jens , Kucinski Thomas , Koch Christoph , Schleper Bert , Foth Mascha , von Michael Bezold , Weiller Cornelius , Zeumer Hermann , Roether Joachim
Published: March 2022

P31

Animal experiments indicated that the severity of the apparent diffusion coefficient (ADC) decrease might serve as indicator of tissue viability. We followed the temporal and spatial development of ADC values after acute human stroke to test this hypothesis. Methods We enrolled 10 consecutive patients with acute ischemic stroke during the last 4 hours. Multimodal MRI (DWI, PWI, MRA, T2w) was performed within 4 h after symptom onset and at days 1 and 7. NIH-stroke-scale was assessed. The mean ADC value for the not affected hemisphere served as reference for the relative ADC-reduction of <50%, 50–60%, 60–70% and 70–80%. Volume of these regions was determined for each imaging timepoint using a threshold function. In a second approach we transferred the previously obtained ADC-theshold areas of day 0 to day 1 and 7 for detection of ADC-changes to determine ADC-changes in reference to the initial ADC. Results In 4 patients with clear neurological improvement at day 1 we found a mean reduction of the ADC- lesion“-volume to 56%. The ADC-threshold-volume of 70–80% increased by 38.9% and areas below 70% decreased by between 56.7% (<50% ADC) and 23.5% (60–70%). Some areas with severe ADC decreases showed partial pseudo-normalization (lesion in T2w / normal ADC values, n=3) and normalization (normal T2w / normal ADC values, n=1) at day 1 and 7. Patients without change or a minor clinical improvement showed a mean increase of the ADC-lesion size at day 1 by 83.6 %. In these patients volume with ADC<50% increased by 275.7% while 70–80%-threshold-volume decreased to 52.2%. ADC values within the initial ADC-threshold-volumes differed significantly at day 1 (n=7), reflecting a different dynamics dependent on the initial ADC. Conclusion Ischemic tissue with severe ADC decreases may recover completely. However, areas with severe ADC decreases usually transform towards a less severe decrease in patients with good neurological recovery. In patients without clinical improvement the area of severe diffusion impairment spreads to adjacent areas.
Safety and Speed of a CT Imaging Protocol for the Entire Cerebrovascular Axis During Acute Stroke
Authors: Smith Wade S , Johnston S Claiborne , Tsao Jack W , Dillon William P , Roberts Heidi C
Published: March 2022

P33

Background:
Newer generation CT scanners allow for rapid contrast enhanced imaging of the neurovascular axis during acute stroke.
Methods:
Using a multidetector CT scanner (GE Lightspeed®) we utilized the following imaging protocol in 38 consecutive patients: noncontrast axial CT of the brain (3.5 mm thickness), dynamic CT perfusion, and CT angiography from vertex to aortic arch (110 cc contrast using 18–20 ga IV at 3–4 cc/sec, scan delay 20 sec, 3:1 pitch, slice thickness 1.25 mm, 120 KV, 170 MA.)
Results:
Serum creatinine was unchanged in all subjects from baseline to hospital discharge; renal failure was not observed (table). One case of contrast extravasation occurred. Total imaging time was 27 ± 16 mins (mean ± SD; range 9–100 mins). Image quality was degraded by motion in 3 studies (7.9%). CTA was 91% sensitive (10 of 11 vessels) and 89% specific (32 of 36 vessels) for carotid disease compared with duplex, MRA and/or conventional angiography. Three of 3 cervical carotid occlusions were correctly identified by CTA. In the 35 patients imaged because of suspected stroke, 4 large vessel occlusions and 11 intracranial stenoses were revealed by review of acute CTA partition images.
Conclusions:
High-speed, multislice spiral CT scanners allow rapid and safe imaging of the entire cerebrovascular axis in patients with acute stroke and may reduce the need for additional imaging.
Correlation of Clinical Outcome and CT/MR in Acute Stroke Patients with Normal Cerebral Angiography
Authors: Calendine Philip E , Christoforidis Greg A , Bourekas Eric C , Notestine Margaret A , Slivka Andrew P
Published: March 2022

P38

Objective:
To examine clinical outcome of patients presenting with acute stroke who have normal cerebral angiography.
Methods:
From November 1994 to June 2000, patients with stroke onset of less than 6 hours underwent cerebral angiography prior to intra-arterial thrombolysis. Seventeen patients (15 male, 2 female; mean age 64, range 42–89) with a discharge diagnosis of stroke had normal cerebral angiography. Admission NIH stroke scale (NIHSS) and Rankin score at discharge were obtained in all patients, as well as follow-up CT and/or MR greater than 24 hours after symptom onset. Good outcome was defined as a Rankin score of 0,1, or 2. Poor outcome was defined as a Rankin score of 3 or greater. Patients were divided into 2 categories based on CT/MR findings: lacunar infarct (single or multiple) and cortical infarct. Discharge Rankin scores were correlated with admission NIHSS and findings on follow-up CT/MR.
Results:
All patients had a discharge Rankin score of 4 or less. Eleven (65%) patients had a poor outcome at discharge and 6 (35%) had a good outcome at discharge. No patient had a normal follow-up CT/MR. All patients with a poor outcome at discharge had a new infarct on follow-up CT/MR. Seven had a new lacunar infarct and 4 had a new cortical infarct. Five (83%) of the 6 patients with good outcome at discharge had new infarcts, 3 lacunar, and 2 cortical. The sixth patient in this group had no new infarct. Admission NIHSS did not correlate with a poor outcome at discharge (Rankin >2; p>0.05, Mann-Whitney).
Conclusion:
Our results indicate that the majority of patients presenting with acute stroke who have a normal angiogram will have a poor clinical outcome at discharge. Niether admission NIHSS nor follow-up CT/MR were found to reliably predict patient outcome at discharge.
Lack of agreement between transcranial Doppler and Xe/CT cerebral blood flow in the detection of cerebrovascular reserves in patients with carotid occlusive disease
Authors: Pindzola Ronda R , Balzer Jeffrey R , Nemoto Edwin M , Goldstein Steven , Yonas Howard
Published: March 2022

P41

Introduction:
Transcranial Doppler ultrasonography (TCD) has been used to identify patients with compromised cerebrovascular reserve(CVR). Patients with compromised CVR have been shown to have an increased risk for stroke. Transcranial Doppler, however, has not been compared to the high resolution quantitative cerebral blood flow (CBF) method of stable xenon enhanced computed tomography (Xe/CT).
Methods:
Cerebrovascular reserves before and after acetazolamide administration (1 gram, i.v.) were measured by TCD insonation of the middle cerebral artery (MCA) and Xe/CT CBF. Thirty-one patients with carotid occlusive disease were studied. Calculations were based on two methods; for the first method Xe/CT CBF values were averaged over 4 levels of the MCA, the second method used the value for the MCA level with the lowest percent change. The threshold for identifying compromised CVR versus non-compromised CVR was 0% change(two standard deviations below normal)for both the TCD and the Xe/CT CBF analyses. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated.
Results:
For the average MCA territory analyses TCD compared to Xe/CT CBF had a 42% sensitivity, a 90% specificity, a 50% positive predictive value and a 86% negative predictive value. The comparison of TCD to Xe/CT using the lowest MCA territory analysis for the Xe/CT CBF values also gave a sensitivity of 42%. The specificity and positive predictive value were both 100% and the negative predictive value was 72%. Discussion/
Conclusion:
The sensitivity of TCD compared to Xe/CT CBF indicates a significant lack of agreement in identifing those patients with compromised CVR. The negative predictive value indicates that the number of patients identified with positive CVR (i.e. negative for compromised reserves)is not the same as with Xe/CT CBF. Physicians should consider this lack of correlation when using TCD to identify patients with compromised CVR. A direct prospective comparison to PET or a clinical prediction of stroke by Xe/CT needs to be done in order to determine the best technology.
Paradoxical embolization in patients with cryptogenic stroke
Authors: Cramer Steven C , Maki Jeffrey H , Waitches Gayle M , Grotta James C , Burgin W Scott , Kramer Larry A
Published: March 2022

P43

BACKGROUND:
The increased prevalence of patent foramen ovale (PFO) in patients with cryptogenic stroke suggests the occurrence of paradoxical embolism. Previous studies have found paradoxical embolism to be uncommon in stroke, but few have focussed on patients with cryptogenic stroke. We therefore evaluated pelvic veins and leg veins in this population.
METHODS:
Eighteen patients (median age 45 years) with a cryptogenic brain ischemic event (stroke 16, TIA 2) underwent magnetic resonance venography (MRV). Evaluation consisted of time-of-flight (TOF) and phase contrast images through the pelvis. A positive MRV was defined as an intravascular decrease in signal intensity at least 15 millimeters (mm) in length contacting the wall of a vein and showing matching abnormalities on both pulse sequences. Lower extremity venous duplex examination was also performed in 17/18.
RESULTS:
All patients had normal cranial arteries, apart from the artery referable to the index stroke. A right-to-left intracardiac shunt was identified in 16/18. MRV was performed a median of 22 days (range, 2–416) post-event. In three patients, only the TOF was performed (all negative studies). There were three patients who had evidence for paradoxical embolism. Patient 1 had sickle cell disease and two small cortical emboli, a PFO, a 30 mm left external iliac vein clot three days post-stroke, and a right calf vein clot diagnosed 23 days post-stroke. Patient 2 had a history of right knee injury and surgery, top of the basilar embolus, a PFO, and a chronic clot in the distal right popliteal vein. Patient 3 had several hours of sudden dysarthria and confusion after pelvic surgery, a PFO, and a right calf vein clot two days post-TIA. One patient had a basilar artery embolus and a 20 mm right external iliac vein clot, but no PFO. Another patient had no DVT day 2 post-stroke, but bilateral calf vein DVT on day 10.
CONCLUSIONS:
Pelvic MRV has diagnostic utility in the evaluation of patients with cryptogenic stroke. Pelvic vein and calf vein thrombosis are a source of paradoxical embolism in some patients with cryptogenic stroke. The incidence of thrombus in these two sites requires further evaluation in this population.
Diffusion-Weighted MR Imaging in Cerebral Venous Thrombosis
Authors: Chu Kon , Kang Dong-Wha , Han Moon-Ku , Yoon Byung-Woo , Chang Kee-Hyun , Roh Jae-Kyu
Published: March 2022

P48

Background:
Cerebral venous thrombosis (CVT) has been an undetermined cause of stroke with an obscure pathophysiology that differs from arterial stroke; its main pathophysiology consists of blood-brain barrier breakdown and coexistence of cytotoxic and vasogenic edema. Conventional MRI cannot allow a prospective differentiation between vasogenic and cytotoxic edema. Diffusion-weighted MRI (DWI) has been reported to detect early ischemic damage (cytotoxic edema) as bright high signal intensity (SI) and vasogenic edema as heterogenous SI. We report various DWI findings in eight patients with CVT.
Objectives:
To determine the DWI findings and pathophysiology of CVT
Results:
From November 1998 to July 2000, eight consecutive patients (two men, six women, age 46 ± 11 years) with CVT underwent DWI, conventional MRI, MR venography and/or conventional cerebral angiography. DWI findings were grouped as three patterns. The first pattern was heterogenous SI (five patients). Bright high SI and low SI were mixed and the corresponding apparent diffusion coefficient (ADC) values were inversely correlated to the DWI SI. The areas of prominent low SI were reversed with adequate treatment in follow-up MR imagings. Second, multifocal high SI, like acute arterial stroke, was found in two patients. The corresponding ADC values were decreased. The third type was intravascular clot high SI (two patients) with or without parenchymal lesions. In one patient, DWI demonstrated T2-negative lesion without correlative symptoms.
Conclusions:
Herein, we classified DWI abnormalities in CVT and these data suggest that DWI can be utilized for discriminating types of edema for tissue viability, detecting subclinical abnormality for preventing further deterioration, and furthermore basic research about the mechanisms of cell death in CVT.
Multiparametric MRI defines tissue signatures compatible with reversible acute cerebral ischemia
Authors: Mitsias Panayiotis D , Pasnoor Mamatha , Hammoud Rabih , Jacobs Michael A , Santhakumar Sunitha , Papamitsakis Nikolaos Ih , Soltanian-Zadeh Hamid , Lu Mei , Chopp Michael , Patel Suresh C
Published: March 2022

P49

Background-Objectives:
Cerebral ischemia results in heterogeneous tissue changes with distinct MRI features that differ from those of normal tissue. Segmentation of the ischemic lesion by multiparameter MRI generates different tissue clusters reflecting various degrees of tissue damage. Defining the MRI features of ischemic tissue that is capable of recovery could aid in the selection of patients for acute phase treatment. We performed this study in order to define the MRI characteristics of ischemic lesion clusters [tissue signatures (TS)] that have potential for recovery by using the computer segmentation algorithm Iterative Self-Organizing Data Analysis Technique (ISODATA).
Methods:
We included patients with acute ischemic stroke (IS) who received no thrombolysis and completed the multiparameter MRI studies at acute (≤12h) and chronic (≥3 months) time points. The MRI protocol included DWI, T2WI and T1WI. Post-processing analysis by ISODATA segmented the lesion into clusters and assigned a TS number to each based on the Euclidean distance between the the cluster and the normal tissue centers. White matter is represented by TS1,CSF by TS12, and all other clusters range between these two. We then identified acute time point TS that recovered (normal TS 1) by loading the chronic T2 lesion region of interest (ROI) onto the acute ISODATA image of the corresponding slice and location. ADC and T2 ratios were calculated by loading TS ROI onto ADC & T2 maps.
Results:
We studied 10 patients (age 56±14ys). We identified TS 2–8 in the acute ischemic lesions. TS 2 (n=1), TS 3 (n=1), TS 4 (n=9), TS 5 (n=4) and TS 6 (n=6) consisted part of the acute ischemic lesion that resolved by the chronic time point. TS ≥7 did not recover. The characteristics of the TS that recovered were: rADC = 0.738 (±0.137) and rT2 = 1.206 (±0.166).
Conclusions:
These preliminary data indicate that ISODATA-defined tissue signatures ≤6, consisting of low rADC and elevated rT2, still have the potential to recover. Consequently, ischemic lesions revealed by DWI and T2 are not necessarily irreversible. These findings should be considered in the design of MRI-based acute stroke treatment trials.
Sensitivity and Specificity of Quantitative Cerebral Blood Flow vs. Time from Symptom Onset as a Predictor of Cerebral Infarction
Authors: Kilpatrick Megan M , Goldstein Steven , Yonas Howard , Kassam Amin B , Gebel James , Wechsler Lawrence R , Jungreis Charles A , Fukui Melanie
Published: March 2022

P50

Background and Purpose:
To compare the sensitivity and specificity of quantitative cerebral blood flow (qCBF) vs. time from symptom onset to the measurement of qCBF (Time) as a predictor of cerebral infarction in patients (pts.) with acute ischemic stroke.
Methods:
51 pts. with acute ischemic stroke who were assessed with XeCT, CTA and CT within 24 hours of symptom onset were studied. The MCA territory was divided into anterior and posterior divisions (two divisions/pt. for a total of 102 divisions). The average qCBF for each of these divisions was calculated and initial and follow-up CT scans were read for new infarction in both divisions. 24 divisions with evidence of prior infarction on the initial CT were excluded from the analysis. This left a total of 78 divisions available for analysis. Logistic regression was used to generate receiver operating curves (ROC) for both qCBF and Time. The area under each ROC curve is reported.
Results:
Twenty-one of the 78 (26.9%) divisions without initial infarction on CT had evidence of new infarction on the follow-up CT. The area under the qCBF curve was 0.81 compared with an area of 0.49 under the Time curve (p=0.00025). Excluding patients receiving thrombolytic therapy, (n=11), the area under the qCBF curve was 0.799 and the area under the Time curve was 0.590 (p=0.00004). The area under the ROC curve for qCBF was significantly greater than Time in those patients studied < 180 minutes (qCBF=0.92, Time=0.51; p=0.02) and > 180 min. (qCBF=0.76, Time=0.50; p=0.01)
Conclusion:
Quantitative cerebral blood flow measured by XeCT is a better predictor of new infarction on follow-up CT than Time in pts. with acute ischemic stroke. This holds true for time < 180 minutes and > 180 minutes.
High Resolution Bold Venography (HRBV) MR Imaging of Acute Stroke
Authors: Vo Katie D , Lee Jin-Moo , Lin Weili , Celik Azim , Lee Yueh , Acharya Aninda B , Kido Daniel K , Hsu Chung Y
Published: March 2022

P52

With PET, elevated OEF in ischemic tissue is normally observed immediately after the onset of ischemia, followed by decreased OEF when ischemic tissue becomes irreversible damaged. This temporal alteration of OEF can potentially be reflected in the small cerebral veins within and/or adjacent to the ischemic tissue as an alteration in the level of blood oxygen saturation. A MR imaging method, referred to as HRBV, was employed to elucidate the temporal alteration of small cerebral veins adjacent to the ischemic tissue. Ten patients with hemispheric strokes were prospectively imaged using a high resolution 3D T2*-weighted sequence (TE=47ms). Both magnitude and phase images were obtained. A mask which highlights pixels with the presence of local susceptibility was generated for each slice via the phase images. Finally, HRBV maps were obtained by multiplying the mask with the corresponding magnitude image. In addition, conventional MR techniques including DWI and PWI were obtained. All patients were studied within 6 hrs after onset of stroke (4.2 +1.4 hrs, t1). Follow-up MR images were obtained at 48 hrs (t2) and 3 months (t3). Diffusion-Perfusion mismatch (DPMM) was expressed as a percentage with DPMM=(PWI-DWI)/PWI. The prominence of enlarged veins in the ischemic territory on HRBV images was rated from 0 (absence of prominent veins) to 3 (numerous prominent veins). At t1, 8 patients with marked DPMM (78.6 +4.5 %) had numerous prominent (grade 3) veins in the ischemic region on HRBV images. At t2, a substantial decrease in DPMM (26.3 +10%) was associated with far fewer prominent veins (grade 0–1). One patient with persistent DPMM (69% at t1 and 62% at t2) had grade 3 veins on HRBV at both time points. Another patient with very little DPMM (5%) had very few prominent veins (grade 1) at t1 and absence of veins (grade 0) with no DPMM at t2. At t3, all patients either had an absence or decreased number of veins in the regions of infarction. Our results are in good agreement with the postulated hypothesis that DPMM may indicate the presence of salvageable tissue where HRBV exhibited numerous prominent veins with low blood oxygen saturation while these veins deminished when no DPMM and/or irreversible tissue damage occurred.
Basilar Artery Occlusive Disease in the New England Medical Center Posterior Circulation Stroke Registry
Authors: Voetsch Barbara , Pessin Michael S , Caplan Louis R
Published: March 2022

P57

Most reports on basilar artery (BA) occlusive disease have retrospectively described isolated cases or small series of patients, focusing mainly on clinicoanatomical correlations. To assess the stroke mechanisms, etiologies, clinical and vascular features, and outcome of BA occlusive disease, we analyzed 76 patients (52 men, 24 women; mean age: 62.1 yrs; range: 5 - 87 yrs) prospectively collected in the New England Medical Center Posterior Circulation Stroke Registry between November 1986 and February 1997, with a diagnosis of moderate (50–70%) to severe (>70%) BA stenosis or occlusion. Vascular imaging was done by TCD, catheter angiography or MRA. BA stenosis was found in 51 (67.1%) patients, while 25 (32.9%) had BA occlusion. Most patients (60.5%) had involvement of the mid-portion of the BA. In 44.7% of patients, the occlusive disease was intrinsic to the BA, in 43.4% BA involvement was part of extensive atherosclerosis in the posterior circulation, and 11.8% of patients had embolism to the BA from the heart or proximal arteries. Fifty-two patients (68.4%) had strokes, half preceded by TIAs. The remaining 24 patients presented with TIAs only. The average duration of TIAs was 3.7 months, when excluding 4 patients whose TIAs lasted over 8 yrs. When an infarct was present, the middle posterior intracranial territory including the pons and the anteroinferior cerebellum was most often involved (73.1%). The etiology of the BA lesions was atherothrombotic in 77.6% and the mechanism presumed hemodynamic in 73.7%. Hypertension (64.5%), hyperlipidemia (40.8%) and coronary artery disease (35.5%) were the most frequent risk factors. Among the 9 patients without risk factors, 3 had BA dissections and 2 had basilar migraine. Of patients with a BA stenosis, 50% had no deficits at follow-up, whereas 75% of BA occlusions lead to disability. Embolism to the BA had severe outcome, with major disability or death occurring in 77.8% of patients. The outcome was best in the patients with diffuse atherosclerotic disease. Our data shows that studying the clinical and vascular features helps understand the mechanism, etiology and determine outcome in BA occlusive disease.
Nonconvulsive Status Epilepticus after Subarachnoid Hemorrhage
Authors: Dennis Lyle J , Mayer Stephan A , Connolly E Sander , Claassen Jan , Hirsch Lawrence J , Thompson Tom , Emerson Ronald G
Published: March 2022

P58

Background:
In-hospital seizures have been reported in 3–24% of patients with aneurysmal subarachnoid hemorrhage (SAH). Nonconvulsive status epilepticus (NCSE) after SAH has not been previously described.
Methods:
Between 11/97 and 2/00, we performed continuous electroencephalographic (cEEG) monitoring (Nicolet Bravo system) for at least 24 hours in all SAH patients treated in our NICU with unexplained coma or neurologic deterioration. Electrographic seizures were diagnosed when epileptiform discharges with a discrete onset, offset, and evolution were present on cEEG. All seizures were treated aggressively with intravenous anticonvulsants and continuous-infusion midazolam therapy, as necessary.
Results:

Of 233 SAH patients who survived the first 48 hours of hospitalization, 100 were stuporous or comatose during their hospitalization. Twenty-six of these patients underwent cEEG monitoring, and 8 (31%) were diagnosed with NCSE average of 18 days (range 5–38) after SAH. Five patients were persistently comatose, two deteriorated to stupor, and one deteriorated to coma with eye blinking; none had focal tonic-clonic activity. All patients were on an anticonvulsant at the time of diagnosis. All seizures were partial, consisting of rhythmic runs of epileptiform discharges; only 4 had focal CT pathology related to the seizure focus. Seizure control was achieved in five patients, but only one experienced clinical improvement, which was transient; in the other 3, the seizures could not be controlled. All 8 patients eventually died in the hospital after a period of prolonged coma (mean LOS 51 days); all but 1 had life support withdrawn. In a univariate analysis, increased mean age (68 vs 54 yrs), higher APACHE-2 scores (16 vs 10), Fisher 3/4 blood on CT (100% vs 54%), worst Hunt/Hess grade 4/5 (100% vs 44%), and ventricular drainage (88% vs 36%) were identified as risk factors for NCSE (all P=.005).
Conclusion:
NCSE may occur in 5–10% of SAH patients who deteriorate or fail to awaken from coma. Although the seizures can be terminated with medical treatment, the prognosis for these patients is extremely poor.
MR Imaging of Posterior Fossa Infarcts: FLAIR vs T2-weighted Sequences
Authors: Katzan Irene L , Abou-Chebl Alex , Andrefsky John C , Krieger Derk W , Ross Jeffrey S
Published: March 2022

P60

Background and Purpose:
Fluid-attenuated inversion-recovery (FLAIR)imaging sequences are generally thought to provide superior lesion contrast over T2-weighted sequences in MR imaging of nonacute ischemic infarcts. To evaluate whether this applies to lesions in the posterior fossa in particular, we compared the conspicuity of posterior fossa infarcts negative on diffusion-weighted imaging between FLAIR and T2-weighted sequences.
Methods:
Administrative and Radiology databases were used to identify neurology outpatients at a tertiary care center who underwent brain MRs in 1999 demonstrating brainstem infarcts. Contrast-to-Noise Ratios (CNR = (S
lesion
- S
background
)/SD
air
))were computed for the lesions on the axial fast spin echo T2-weighted and FLAIR images. Lesion conspicuity was qualitatively compared between the two imaging sequences by two stroke neurologists unaware of the study question.
Results:
There were 8 pontine and 13 cerebellar infarcts identified on 19 brain MRs. Mean repetition and echo times were 3537 (SD±122) and 93 (SD±3), respectively, for the T2-weighted images and 7143 (SD ±1014)and 105 (SD ± 0) for the FLAIR images. The mean Contrast-to-Noise Ratio was significantly higher in the T2-weighted images (26.3, SD ±18.9) than the FLAIR images (2.4, SD ±4.3) (p< 0.001). Conspicuity was judged to be superior on the T2-weighted images significantly more often by both stroke neurologists (86%, 95%, p= 0.001).
Conclusion:
T2-weighted images may provide better lesion contrast in nonacute posterior fossa infarcts than FLAIR images. Careful attention to the T2-weighted images may assist in the detection of nonacute pontine and cerebellar ischemic infarcts.
In Vivo Microvascular Analysis of Albumin Therapy in Focal Cerebral Ischemia: Dynamic Laser Confocal Microscopy.
Authors: Belayev Ludmila , Pinard Elisabeth , Nallet Helene , Seylaz Jacques , Liu Yitao , Zhao Weizhao , Busto Raul , Ginsberg Myron D
Published: March 2022

P65

To study whether hemodynamic alterations are responsible for the marked neuroprotective effect of albumin in focal ischemia, we used a newly developed method for studying brain microcirculation, combining in vivo fluorescence microscopy of labeled erythrocytes and plasma with confocal microscopy. Sprague-Dawley (SD) rats were anesthetized with halothane/nitrous oxide, and a cranial window was placed in the dorsolateral frontoparietal cortex. Cortical direct current (DC) potential was also recorded. Rats received 2h middle cerebral artery occlusion (MCAo) by intraluminal suture coated with poly-L-Lysine and were treated with human albumin (Alb, n=4, 1.25g/kg) or saline (Sal, n=3) following 30 min of recirculation. Video images of cortical vessels were continually acquired and were digitized off-line to measure diameters and flow velocities. In separate experiments, anesthetized SD rats received 2h MCAo and were treated with Alb (2.5g/kg; n=6),) or Sal (n=5) 15 min after recirculation. Laser Doppler Perfusion Imaging (LDPI) was measured. MCAo was associated with arteriolar dilatation and slowing of capillary and venular perfusion together with recurrent DC depolarizations. During the first 15–30 min of postischemic recirculation, prominent foci of vascular stasis developed within cortical venules, associated with thrombus-like stagnant foci and adherent intra-venular corpuscular structures. Sal administration failed to affect these phenomena, while Alb therapy was followed in many cases by improvement of venular flow and disappearance of adherent corpuscules and thrombotic material. In the LDPI study, CBF declined during MCAo and rose initially with recirculation (to 130%) identically in Alb and Sal rats. Alb led to an additional sustained CBF increase of 17% (p<.0001), but Sal caused no further change. These results support the strong beneficial effect of Alb therapy in focal ischemia and suggest its possible utility in treating patients with acute ischemic stroke. Supported by AHA Init. Invest. Award, NIH Grant NS05820 and an equipment loan from Moor Instruments, Ltd.
Experimental Stroke Alters Depressive-like Behavior in Mice.
Authors: DeVries A. Courtney , Hattori Kimihiko , Traystman Richard J , Hurn Patricia D
Published: March 2022

P68

Depression is a common consequence of stroke in humans and is associated with an increase in cognitive deficits and impaired functional recovery. However, the etiology of post-stroke depression remains unknown. The purpose of the present study was to determine if focal cerebral ischemia in mice induces changes in a rodent behavioral model of depression that can be reversed through treatment with fluoxetine,a selective serotonin reuptake inhibitor. Increased time spent immobile versus actively swimming in the Porsolt Swim Test is a commonly used index of depressive-like behavior in rodents. Male C57/BL6 mice were subjected to a 2 min forced swim one day prior to 60 min middle cerebral artery occlusion (MCAO; using a 6.0 nylon filament) or sham-surgery. Beginning 7 days after surgery, the animals were injected IP daily with fluoxetine or the vehicle. One week later, the animals were subjected to a second swim test and the amount of time spent actively swimming versus immobile was recorded. Experimental stroke increased frequency and time spent immobile during the Porsolt Swim Test. Furthermore, chronic treatment of MCAO animals with 20 mg/kg of fluoxetine restored swimming behavior to SHAM levels (see table). These data suggest that post-ischemic affective disorders can be modeled in animals and are modulated by antidepressants.