An Investigation of Water Diffusivity Changes along the Perivascular Space in Elderly Subjects with Hypertension.

BACKGROUND AND PURPOSE: Hypertension may be related to alterations of the glymphatic system, a waste metabolite drainage system in the brain. We aimed to investigate analysis along the perivascular space index changes in elderly subjects with hypertension. MATERIALS AND METHODS: Diffusion-weighted images were acquired from 126 subjects, including 63 subjects with hypertension (25 men and 38 women; mean age, 72.45 years) and 63 age- and sex-matched controls (25 men and 38 women; mean age, 72.16 years). We calculated the analysis along the perivascular space index as a ratio of the mean of x-axis diffusivities in the projection and association areas to the mean of y-axis diffusivity in the projection area and z-axis diffusivity in the association area. The left, right, and mean analysis along the perivascular space indices of both hemispheres were compared between the hypertension and control groups using a Mann-Whitney U test. The Spearman correlation coefficient was used to assess the correlation between the left, right, and mean ALPS indices and blood pressure and pulse pressure. RESULTS: The left (P = .011) and mean (P = .024) analysis along the perivascular space indices of the hypertension group were significantly lower than that of the control group. The left, right, and mean analysis along the perivascular space indices of all subjects were significantly negatively correlated with blood pressure values (r = -0.200 to -0.278, P = .002-0.046) and pulse pressure values (r = -0.221 to -0.245, P = .006-0.013). CONCLUSIONS: Our results are consistent with a model in which hypertension causes glymphatic dysfunction.

Imaging Differences between Neuromyelitis Optica Spectrum Disorders and Multiple Sclerosis: A Multi-Institutional Study in Japan.

BACKGROUND AND PURPOSE: Both clinical and imaging criteria must be met to diagnose neuromyelitis optica spectrum disorders and multiple sclerosis. However, neuromyelitis optica spectrum disorders are often misdiagnosed as MS because of an overlap in MR imaging features. The purpose of this study was to confirm imaging differences between neuromyelitis optica spectrum disorders and MS with visually detailed quantitative analyses of large-sample data. MATERIALS AND METHODS: We retrospectively examined 89 consecutive patients with neuromyelitis optica spectrum disorders (median age, 51 years; range, 16-85 years; females, 77; aquaporin 4 immunoglobulin G-positive, 93%) and 89 with MS (median age, 36 years; range, 18-67 years; females, 68; relapsing-remitting MS, 89%; primary-progressive MS, 7%; secondary-progressive MS, 2%) from 9 institutions across Japan (April 2008 to December 2012). Two neuroradiologists visually evaluated the number, location, and size of all lesions using the Mann-Whitney U test or the Fisher exact test. RESULTS: We enrolled 79 patients with neuromyelitis optica spectrum disorders and 87 with MS for brain analysis, 57 with neuromyelitis optica spectrum disorders and 55 with MS for spinal cord analysis, and 42 with neuromyelitis optica spectrum disorders and 14 with MS for optic nerve analysis. We identified 911 brain lesions in neuromyelitis optica spectrum disorders, 1659 brain lesions in MS, 86 spinal cord lesions in neuromyelitis optica spectrum disorders, and 102 spinal cord lesions in MS. The frequencies of periventricular white matter and deep white matter lesions were 17% and 68% in neuromyelitis optica spectrum disorders versus 41% and 42% in MS, respectively (location of brain lesions, P < .001). We found a significant difference in the distribution of spinal cord lesions between these 2 diseases (P = .024): More thoracic lesions than cervical lesions were present in neuromyelitis optica spectrum disorders (cervical versus thoracic, 29% versus 71%), whereas they were equally distributed in MS (46% versus 54%). Furthermore, thoracic lesions were significantly longer than cervical lesions in neuromyelitis optica spectrum disorders (P = .001), but not in MS (P = .80). CONCLUSIONS: Visually detailed quantitative analyses confirmed imaging differences, especially in brain and spinal cord lesions, between neuromyelitis optica spectrum disorders and MS. These observations may have clinical implications.

Time course of axial and radial diffusion kurtosis of white matter infarctions: period of pseudonormalization.

BACKGROUND AND PURPOSE: Diffusion kurtosis is a statistical measure for quantifying the deviation of the water diffusion profile from a Gaussian distribution. The current study evaluated the time course of diffusion kurtosis in patients with cerebral infarctions, including perforator, white matter, cortical, and watershed infarctions. MATERIALS AND METHODS: Subjects were 31 patients, representing 52 observations of lesions. The duration between the onset and imaging ranged from 3 hours to 122 days. Lesions were categorized into 4 groups listed above. Diffusion kurtosis images were acquired with b-values of 0, 1000, and 2000 s/mm(2) applied in 30 directions; variables including DWI signal, ADC, fractional anisotropy, radial diffusivity, axial diffusivity, radial kurtosis, and axial kurtosis, were obtained. The time courses of the relative values (lesion versus contralateral) for these variables were evaluated, and the pseudonormalization period was calculated. RESULTS: Diffusion kurtosis was highest immediately after the onset of infarction. Trend curves showed that kurtosis decreased with time after onset. Pseudonormalization for radial/axial kurtosis occurred at 13.2/59.9 days for perforator infarctions, 33.1/40.6 days for white matter infarctions, 34.8/35.9 days for cortical infarctions, and 34.1/28.2 days after watershed infarctions. For perforator infarctions, pseudonormalization occurred in the following order: radial kurtosis, ADC, axial kurtosis, and DWI. CONCLUSIONS: Diffusion kurtosis variables in lesions increased early after infarction and decreased with time. Information provided by diffusion kurtosis imaging, including axial and radial kurtosis, seems helpful in conducting a detailed evaluation of the age of infarction, in combination with T2WI, DWI, and ADC.

Effect of cilostazol in preventing restenosis after carotid artery stenting using the carotid wallstent: a multicenter retrospective study.

BACKGROUND AND PURPOSE: Restenosis after CAS is a postoperative problem, with a reported frequency of approximately 2%-8%. However differences in stent design, procedure, and the antiplatelet agent appear to affect the incidence of restenosis. We assessed the frequency of restenosis and the effect of the antiplatelet agent CLZ in preventing restenosis after CAS by the standard procedure using the CWS. MATERIALS AND METHODS: Between May 2010 and October 2011, 62 lesions in 60 consecutive patients underwent CAS using the CWS at 4 medical institutions, and all patients were followed clinically and assessed by sonography, 3D-CTA, or angiography at 3 and 6 months postoperatively. Restenosis was defined as ≥50% stenosis. The incidence of restenosis and the variation in the incidence of restenosis by the difference in type of antiplatelet agent between the CLZ group (n = 30; aspirin, 100 mg, and CLZ, 200 mg) and the non-CLZ group (n = 32; aspirin, 100 mg, and clopidogrel, 75 mg [n = 29]; or ticlopidine, 100 mg [n = 2] or 200 mg [n = 1]) were retrospectively investigated. Two antiplatelet agents were given starting 1 week preoperatively until at least 3 months postoperatively. RESULTS: Restenosis occurred in 5 patients (8.3%), but all were cases of asymptomatic lesions in the follow-up period. All 5 patients with restenosis were in the non-CLZ group, with no cases of restenosis in the CLZ group; the difference was significant (P = .0239). CONCLUSIONS: The restenosis rate after CAS by using the CWS was 8.3%. CLZ was associated with significant inhibition of restenosis.

Transient hyperintensity in the subthalamic nucleus and globus pallidus of newborns on T1-weighted images.

BACKGROUND AND PURPOSE: In the brains of newborns, changes in signal intensity in most structures can be explained by the development of myelination. However, there are some structures for which signal intensity changes cannot be accounted for by myelination alone. We examined the STN and globus pallidus signal intensities and tried to determine whether a relationship exists between the signal intensity and the postnatal age or the gestational age at the examination. MATERIALS AND METHODS: We examined T1WI and T2WI obtained from 79 neonates who showed normal development at their 2-year follow-up examinations. We performed both qualitative and quantitative (signal intensity ratio to the thalamus) evaluation of the STN and globus pallidus signals, and we examined the correlation between signal intensity changes and the age of neonates. RESULTS: With increasing postnatal age at examination, the high signal intensity on the T1WI for both STN and globus pallidus diminished. Although the disappearance of this hyperintensity was well correlated with the postnatal age at examination for both the qualitative and quantitative studies, there was no correlation with gestational age at examination. For the T2WI, there was no correlation with either the postnatal age or the gestational age at examination. CONCLUSIONS: Signal intensity on T1WI in the STN and globus pallidus is not related to the gestational age at examination; instead, signal intensities on T1WI seem to be more dependent upon the postnatal age at examination.

Fractional anisotropy--threshold dependence in tract-based diffusion tensor analysis: evaluation of the uncinate fasciculus in Alzheimer disease.

BACKGROUND AND PURPOSE: Tract-based analysis can be used to investigate required tracts extracted from other fiber tracts. However, the fractional anisotropy (FA) threshold influences tractography analysis. The current study evaluated the influence of the FA threshold in measuring diffusion tensor parameters for tract-based analysis of the uncinate fasciculus in subjects with Alzheimer disease (AD). MATERIALS AND METHODS: Subjects included 30 patients with AD and 10 healthy controls. We acquired tractographies of the uncinate fasciculus by using different FA thresholds. We measured mean FA and the apparent diffusion coefficient (ADC) along the uncinate fasciculus for different FA thresholds and evaluated the correlation between diffusion tensor parameters (FA, ADC) and the Mini-Mental State Examination (MMSE) scores. RESULTS: The uncinate fasciculus showed lower mean FA and higher mean ADC values in cases with more severe AD. A higher FA threshold led to a lower mean ADC value and a higher mean FA value along the uncinate fasciculus, whereas the relative order of measured values according to the severity of AD was not influenced by the FA threshold. An FA threshold of 0.2 showed higher correlation between mean ADC values and MMSE scores. FA thresholds of 0.15 and 0.20 showed higher correlation between mean FA values and MMSE scores. CONCLUSIONS: Appropriate selection of the FA threshold leads to higher correlation between diffusion tensor parameters and the severity of AD. For tract-based analysis of degenerative diseases such as AD, appropriate selection of the FA threshold for tractography is important.

Diffusion tensor tractography of the Meyer loop in cases of temporal lobe resection for temporal lobe epilepsy: correlation between postsurgical visual field defect and anterior limit of Meyer loop on tractography.

BACKGROUND AND PURPOSE: Visual field defects sometimes occur after temporal resection surgery. Our purpose was to evaluate the correlation between visual field defects caused by temporal lobe resection and the degree of resection of the Meyer loop, as assessed by diffusion tensor tractography. MATERIALS AND METHODS: We examined 14 patients who underwent temporal resection for temporal lobe epilepsy. We obtained presurgical tractographies and then measured the distance between the temporal tip and the anterior limit of the Meyer loop (T-M distance). The degree of resection of the Meyer loop was defined as the distance from the anterior limit of the Meyer loop to the posterior limit of the temporal lobe resection (M-R distance). This was calculated by subtracting the T-M distance from the measured distance between the temporal tip and the posterior limit of the resection (T-R distance). RESULTS: The mean T-M distance was 36.6 mm. The interindividual variation of the distance ranged from 30.0 to 43.2 mm. Although there was no statistically significant correlation between the extent of the visual field defect and the T-R distance, there was a statistically significant correlation between the degree of the visual field defect and the M-R distance. CONCLUSION: The range of interindividual variation for the position of the Meyer loop was rather large, indicating that this variation is the key factor in visual field defects after temporal lobectomy, and the visual field defect appears to be predicted by presurgical tractography. Evaluation of the Meyer loop through the use of tractography seems to be a feasible method, which can be used to predict the visual field defect after temporal lobe resection.

Parasagittal Arachnoid Markings on the Inner Skull on Three-Dimensional CT: Relation between Hydrocephalus and Arachnoid Granules.

The purpose of the study was to evaluate the number and size of arachnoid markings on the inner plate of the skull on 3D-CT. The subjects included 16 hydrocephalus and 26 non-hydrocephalus cases. We evaluated the correlation between age and both the number and sizes of the arachnoid markings, and compared them between hydrocephalus and non-hydrocephalus cases. We also evaluated cases exhibiting a "smooth cranium" that had no arachnoid markings at all on the inner plate. There was a positive correlation between age and the number of the arachnoid markings. There were no statistically significant differences in arachnoid markings between hydrocephalus and non-hydrocephalus cases, while, there were statistically significant differences in the frequency of "smooth cranium" findings in the population under ten years old. The "smooth cranium" can only be seen in hydrocephalus cases. These findings may be a clue to the morphological or functional changes of the arachnoid villi in hydrocephalus cases.

Global and region-specific analyses of apparent diffusion coefficient in dentatorubral-pallidoluysian atrophy.

BACKGROUND AND PURPOSE: Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant spinocerebellar ataxia. Techniques for the quantitative assessment of neurodegenerative lesions remain to be established in this disease. We attempted to quantify global and region-specific neurodegeneration in DRPLA using analysis of apparent diffusion coefficient (ADC) maps. METHODS: Diffusion-weighted images (b = 1000 s/mm(2)) by echo-planar sequences were obtained with the use of a 1.5T clinical scanner. Whole-brain histogram and region of interest (ROI) analyses of ADC values as well as conventional MR imaging studies were performed in 6 patients with genetically confirmed DRPLA. RESULTS: Histograms demonstrated significantly higher mean ADC values in the patients than in age- and sex-matched control subjects (P < .01). ROI analysis revealed that the patients had significantly higher ADC values in the cerebellum and globus pallidus, preferentially affected regions (P < .05), but not in the thalamus, the region relatively spared in this disease. ADC values in the white matter were higher only in patients with adult-onset disease. Histogram analyses could more sensitively identify abnormalities than ROI analyses, because the former avoided errors associated with setting ROIs and thus had smaller P values on statistical analysis than the latter. CONCLUSIONS: Histogram ADC analyses were more sensitive for the detection of neurodegeneration in DRPLA than ROI analyses, whereas ROI analyses revealed regional alterations reflecting the distribution of pathologic changes. Thus, histogram and ROI analyses complement each other and may permit the sensitive, quantitative evaluation of neurodegeneration in DRPLA, especially that involving the globus pallidus showing normal T2 signals.

Diffusion anisotropy and diffusivity of white matter tracts within the temporal stem in Alzheimer disease: evaluation of the "tract of interest" by diffusion tensor tractography.

PURPOSE: Our aim was to determine whether diffusion anisotropy and diffusivity of white matter tracts of the temporal stem in patients with Alzheimer (AD) can be evaluated independently by using diffusion tensor tractography. MATERIALS AND METHODS: Subjects included 15 patients with AD (11 women and 4 men; mean age, 74 years) and 15 age-matched control subjects (11 women and 4 men; mean age, 72 years). Diffusion tensor images were acquired by using echo-planar imaging. We drew tractographies of the uncinate fasciculus, inferior occipitofrontal fasciculus, and Meyer's loop, with diffusion tensor analysis software. We measured diffusion anisotropy, diffusivity, and the number of voxels along the "tracts of interest" and used the Student t test to compare results between patients with AD and controls. RESULTS: Values of diffusion anisotropy of the bilateral uncinate fasciculus and left inferior occipitofrontal fasciculus were significantly lower for patients with AD than for controls. Also, values of diffusivity in the bilateral uncinate fasciculus were significantly greater for patients with AD than for controls. There was no significant difference in diffusion anisotropy or diffusivity along Meyer's loop between the 2 groups. There was no significant difference in the number of voxels included in all constructed tracts between patients with AD and controls. CONCLUSION: White matter tracts of the temporal stem can be evaluated independently by using diffusion tensor tractography, which appears to be a promising technique for determining changes in white matter in degenerative diseases.

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion.

OBJECTIVE: To clarify whether patients with clinical diagnoses of encephalitis/encephalopathy with a reversible lesion in the splenium of the corpus callosum (SCC) share common clinical features. METHODS: Possible encephalitis/encephalopathy patients with a reversible isolated SCC lesion on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed. RESULTS: Fifteen encephalitis/encephalopathy patients with a reversible isolated SCC lesion were identified among 22 patients referred for this study. All 15 patients had relatively mild clinical courses. Twelve of the 15 patients had disorders of consciousness. Eight patients had seizures, and three of them received antiepileptic drugs. All 15 patients clinically recovered completely within 1 month (8 patients within a week) after the onset of neurologic symptoms. The SCC lesion was ovoid in six patients; it extended irregularly from the center to the lateral portion of SCC in the other eight patients. Homogeneously reduced diffusion was seen in all seven patients who underwent diffusion-weighted imaging. There was no enhancement in the five patients so examined. The SCC lesion had completely disappeared in all patients at follow-up MRI exams between 3 days and 2 months after the initial MRI (within 1 week in eight patients). CONCLUSION: The clinical features among the affected patients were nearly identical, consisting of relatively mild CNS manifestations and complete recovery within 1 month.

Vasogenic edema and VEGF expression in a rat two-vein occlusion model.

Vasogenic edema plays an important etiologic role in the pathogenesis of cerebral venous circulation disturbances (CVCDs). Since vascular endothelial growth factor (VEGF) is a major mediator in angiogenesis and vascular permeability, including induction of vasogenic edema, the present study was undertaken to investigate whether it has any relevance to CVCDs. Male Wistar rats (n = 15) were used. Two adjacent cortical veins were occluded photochemically using rose bengal dye and fiberoptic illumination, with evaluation 24 hours thereafter by magnetic resonance imaging (MRI). Each brain was removed from the skull immediately after MRI and processed for hematoxylin-eosin staining (H&E staining) of sections for histopathology and comparison with MRI data. VEGF expression as demonstrated immunohistochemically appeared to coincide with vasogenic edema, diagnosed as high intensity areas on apparent diffusion coefficient of water (ADCw) maps. On the basis of these data, we conclude that VEGF is related to formation of vasogenic edema in the acute stage of CVCD.

Factors influencing visualization of vertebral metastases on MR imaging versus bone scintigraphy.

OBJECTIVE: The purpose of this study was to investigate whether the location and size of vertebral body metastases influence the difference in detection rates between MR imaging and bone scintigraphy. MATERIALS AND METHODS: We retrospectively evaluated the vertebral body lesions detected on MR imaging in 74 patients with known widely disseminated metastatic disease. Three radiologists independently reviewed the MR images and bone scintigraphs. MR imaging findings included lesion size and its spatial relationship to the bony cortex (intramedullary, subcortical, and transcortical) and results were correlated with those of planar technetium 99m bone scintigraphy. RESULTS: Findings on bone scans were negative for all intramedullary lesions without cortical involvement shown on MR imaging, regardless of their size. Findings on bone scans (71.3% for transcortical and 33.8% for subcortical) were frequently positive for lesions with cortical involvement (trans- or subcortical), and the probability of positive findings on bone scans was also influenced by the lesion size. Statistical analysis showed a positive correlation among cortical involvement, lesion size, and positive findings on bone scintigraphy (p < 0.0001). CONCLUSION: Location (the presence of cortical bone involvement on MR imaging) and size of the vertebral body metastases appear to be important contributing factors to the difference in detection rates between MR imaging and bone scintigraphy. Cortical involvement is likely the cause of positive findings on bone scans. Early vertebral metastases tend to be small and located in the medullary cavity without cortical involvement, and therefore, findings may be positive on MR images but negative on bone scans.

Sulcal hyperintensity on fluid-attenuated inversion recovery mr images in patients without apparent cerebrospinal fluid abnormality.

OBJECTIVE: Failure to suppress cerebrospinal fluid (CSF) signal intensity (sulcal hyperintensity) on fluid-attenuated inversion recovery (FLAIR) images has been reported in patients with abnormal CSF, such as those with meningitis and subarachnoid hemorrhage. Our study investigates the clinical history and MR findings associated with sulcal hyperintensity on FLAIR images in patients without apparent CSF abnormality. SUBJECTS AND METHODS: Three hundred consecutive MR imaging examinations were prospectively screened for patients with sulcal hyperintensity on FLAIR images. Nine patients with clinical, CT, or laboratory evidence suggesting abnormal CSF were excluded. The distribution of sulcal hyperintensity on FLAIR images and associated abnormal enhancement were evaluated. The presence of the "dirty CSF" sign (mild increase in CSF signal on unenhanced T1-weighted images or mild decrease on T2-weighted images) in the corresponding hyperintense sulcus was also assessed. RESULTS: Twenty-six (8.9%) of the 291 patients had sulcal hyperintensity (16 focal, 10 diffuse) associated with 18 masses (6.1%) and eight vascular abnormalities (2.7%). Sulcal hyperintensity was frequently associated with the dirty CSF sign (69.2%) and abnormal contrast enhancement (overall, 96.2%; 88.5%, leptomeningeal; 53.8%, vascular enhancement). CONCLUSION: Our study shows that sulcal hyperintensity on FLAIR imaging can occur in patients without apparent CSF abnormality. Its frequent association with mass effect, vascular disease, abnormal vascular enhancement, and dirty CSF sign suggests that an increase in blood pool, a small amount of protein leakage, and the "flow-entering" phenomenon of the congested blood may contribute to sulcal hyperintensity on FLAIR images.

Detection of early venous filling in gliomas on MRI: preliminary study by 2D time-resolved dynamic contrast-enhanced MR angiography with echo-sharing technique.

We evaluated the detection of early venous filling of gliomas by 2D time resolved dynamic contrast enhanced MR digital subtraction angiography (MR-DSA) with echo-sharing technique and compared the results with those of conventional contrast digital subtraction angiography (C-DSA). C-DSA and MR-DSA examinations were performed in eight patients with malignant gliomas and compared with regard to the visualization of early filling veins; time intensity curves of arteries, early filling veins and normal veins were made, and rise time and time to peak were evaluated. MR-DSA visualized 12 out of 17 early filling veins depicted on C-DSA. The failure of five veins to be depicted may be due to the overlapping of other structures, such as other vessels and tumor stain. On time intensity curves, the mean difference in rise time was 0.9 sec between the artery and early filling vein, and the mean difference of time to peak was 1.6 sec. C-DSA has been the modality of choice in demonstrating early venous filling, a useful finding in the differential diagnosis of gliomas. However the high temporal resolution of MR-DSA with echo-sharing technique provides sufficient visualization of early venous filling of gliomas. Additional information for precise differential diagnosis may be obtained by adding MR-DSA to the imaging protocol for gliomas.

Palmaz stent deployment for subclavian and brachiocephalic arterial occlusive disease. Factors predictive of restenosis.

SUMMARY: Palmaz stent deployment is a useful method for subclavian and brachiocephalic arterial occlusive disease. We evaluated restenosis or intimal thickening after Palmaz stent deployment for nine lesions of subclavian or brachiocephalic arterial occlusive disease focusing on stent diameter, atheroma thickness near the stent, and degree of coverage for the lesion. Follow up DSA and IVUS at 5-14 months (mean 9) after therapy showed no significant changes in the size or shape of the stent itself There were two lesions of thin in-stent intimal hyperplasia and five lesions of thick hyperplasia. There was no close relationship between intimal hyperplasia and stent diameter or atheroma size (relative thickness). There was some relationship between the degree of coverage of the lesion by the stent and degree of intimal hyperplasia, but to determine statistical significance, accumulation of a greater number of cases is necessary.

MR imaging of pituitary morphology in idiopathic intracranial hypertension.

The aim of this study was to investigate the morphologic changes of the pituitary gland in patients with the clinical diagnosis of idiopathic intracranial hypertension (IIH). Qualitative and quantitative analyses of pituitary morphology were performed in normal subjects (n = 23), patients with the clinical diagnosis of IIH (n = 40), and patients with acute increased intracranial pressure (AICP; n = 37) caused by acute head trauma. The loss of pituitary height (concavity) on the sagittal T1-weighted image was classified into five categories: I = normal, II = superior concavity that was mild (<(1/3) the height of the sella), III = moderate (between (1/3) and (2/3) concavity of height of sella), IV = severe (>(2/3) concavity of height of sella), and V = empty sella. The area ratio of pituitary gland to sella turcica measured in the midsagittal plane was quantified. Clinical records were retrospectively reviewed to correlate with magnetic resonance (MR) findings. Using moderate concavity (>(1/3)) as the minimum criterion for abnormality, IIH patients had an 85% incidence of morphologic changes with 80% sensitivity and 92% specificity. Empty sella (almost complete concavity of the sella) was found in only 2.5% of patients with IIH. Quantitative analysis of the pituitary gland/sella turcica area ratio showed a significant decrease in patients with IIH (P < 0.0001) but no significant difference between the normal subjects and AICP patients. A posterior deviation of the pituitary stalk was seen in 43% of patients. No enlargement of the ventricles or sulcal effacement was seen in IIH patients. Routine brain MR examination of patients with IIH frequently shows morphologic changes of the pituitary gland ranging from various degrees of concavity to (rarely) the extreme case of an empty sella. The etiology is unknown and may be related to the severity and duration of elevated CSF pressure. Such findings may be useful to facilitate the diagnosis of IIH, particularly in patients with equivocal clinical findings or when IIH is not suspected. J. Magn. Reson. Imaging 2000;12:808-813.

Enhancement pattern of normal extraocular muscles in dynamic contrast-enhanced MR imaging with fat suppression.

PURPOSE: To evaluate the internal structure of normal extraocular muscles on fat-suppressed dynamic contrast-enhanced MR imaging. MATERIAL AND METHODS: Ten subjects were examined using fat-suppressed dynamic contrast-enhanced MR imaging. We evaluated the enhancement pattern (C-shaped or ring-like) of extraocular muscles and quantified the maximum ratios of enhancement (Rmax) and maximum ratios of signal increase (Vmax). We also quantified Rmax and Vmax in the central and peripheral portions of medial rectus muscles. RESULTS: In the early phase of dynamic contrast-enhanced MR imaging, a C-shaped or ring-like pattern was observed in 100% of inferior rectus, 95% of medial rectus, 55% of superior rectus, 20% of lateral rectus, and 15% of superior oblique muscles. Overall mean Rmax and Vmax values showed statistically significant differences to the temporal muscles. For the peripheral portion of medial rectus muscles, mean Rmax and Vmax values were greater than for the central portion. CONCLUSION: Using fat-suppressed dynamic contrast-enhanced MR imaging, the C-shape or ring-like internal structure of the extraocular muscles could be visualized, and were considered to reflect their structure of orbital and global layers. Potential usefulness of the fat-suppressed dynamic contrast-enhanced MR imaging for detecting pathological status is suggested.

Hippocampal damage in the human brain after cardiac arrest.

BACKGROUND AND PURPOSE: Very few reports are available on changes in the human hippocampus after cardiac arrest. The objective of this study was to investigate if specific hippocampal volume losses can be demonstrated in the human brain following reperfusion after cardiac arrest. METHODS: We assessed the volumes of the hippocampal formation (HF) and temporal lobe excluding HF (TL) as the contrast using magnetic resonance (MR)-imaging-based volumetry in 11 vegetative patients after cardiac arrest and in 22 healthy controls of similar age, sex and body size distribution. The measured volumes were normalized for differences in the head size among subjects by dividing by the total intracranial volume (TICV). The MR images of the 11 patients were obtained between days 8 and 21 after cardiac arrest. RESULTS: The observed volumes of HFs and TLs of both patient and control groups were as follows: right HF volume (HFV): 2.67 +/- 0.19 (mean +/- SD, cm(3)) in patients versus 3.89 +/- 0.44 in controls; left HFV: 2.72 +/- 0.17 versus 3.74 +/- 0.35; right TL volume (TLV): 73.37 +/- 6.54 versus 80.08 +/- 7.62, and left TLV: 72. 45 +/- 6.77 versus 78.59 +/- 6.68. The normalized indices (HFV/TICV and TLV/TICV) were as follows: right HF: 0.0021 +/- 0.0002 (mean +/- SD) in patients versus 0.0031 +/- 0.0001 in controls, p < 0.0001, left HF: 0.0022 +/- 0.0002 versus 0.0030 +/- 0.0001, p < 0.0001, right TL: 0.058 +/- 0.002 versus 0.064 +/- 0.004, p = 0.0007, and left TL: 0.058 +/- 0.002 versus 0.062 +/- 0.004, p = 0.0014. The HFV-TLV ratios (HFV/TICV divided by TLV/TICV) of both groups were: right HFV-TLV ratio: 0.037 +/- 0.004 in patients versus 0.049 +/- 0. 004 in controls, p < 0.0001, left HFV-TLV ratio: 0.038 +/- 0.004 versus 0.048 +/- 0.004, p < 0.0001. CONCLUSIONS: The patient group had HFs that were 26.8-30.6% smaller than those of the control group, but in the patient group, the TLs slightly decreased in size by only 7.8-8.2% of the volume of those in the control group within 21 days after cardiac arrest. The volume reductions in the bilateral HFs of patients after cardiac arrest were significantly larger than those in the bilateral TLs. We speculate that this specific rapid hippocampal shrinkage reflects its greater vulnerability to global brain ischemia.