Intracranial fat embolization due to baclofen pump.
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Adult↗
Biomedical subjects
G Moonis
Publications and source records attributed to G Moonis.
Simultaneous bilateral internal carotid and vertebral artery dissection following chiropractic manipulation: case report and review of the literature.
Single-vessel cervical arterial dissections typically occur in young adults and are a common cause of cerebral ischemia and stroke. Although the pathogenesis of multivessel dissection is unclear, it is thought to be a consequence of underlying collagen vascular disease. We present a 34-year-old previously healthy man who developed bilateral internal carotid and vertebral artery dissection following chiropractic manipulation.
Adult↗
Computing diffusion rates in T2-dark hematomas and areas of low T2 signal.
BACKGROUND AND PURPOSE: It has been suggested that restricted diffusion is present within hematomas with intact red cell membranes; however, computing apparent diffusion coefficient (ADC) values in areas of low T2 signal can be problematic. Our purpose was to show the pitfalls of measuring diffusion within hematomas with intracellular blood products and to present a framework based on the properties of expected values for computing ADC values from regions with signal intensities close to that of the background noise (ie, T2-dark hematomas). METHODS: Twelve patients with intracranial hematomas who had undergone diffusion imaging were retrospectively identified during a 2-year period (four intracellular oxyhemoglobin, seven intracellular deoxyhemoglobin, one intracellular methemoglobin). Regions of interest were drawn on the hematomas, the contralateral white matter, and over the background. ADC values were computed using a variety of methods: 1) using expected values incorporating the variance of the background, 2) computing the mean of the regions of interest before taking the natural log, 3) masking negative values, and 4) masking the background at 0.5% increments from 0.5 to 5.5% and including the masked voxels (an intrinsically flawed method). Two-tailed Student's t test was performed between the white matter and the hematoma ADC values. RESULTS: There was no statistically significant difference between the hematomas and the white matter for methods 1 through 3 (P = .14, P = .23, and P = .83, respectively). Only method 4 revealed a statistically significant difference, beginning at 0.5% masking (P = .04) and becoming progressively more significant with increased masking (P = 4.14 x 10(-7) at 5.5% masking). The effect of masking was limited to the T2-dark hematomas. CONCLUSION: There is no restriction of diffusion for in vivo hematomas with intracellular blood products. The T2 blackout effect for T2-dark hematomas on diffusion-weighted images should not be interpreted as fast diffusion. The method of expected values can be used to obtain measurements for regions with signal intensities near the background noise. Using literature values for RBC self-diffusion, we computed lower limits of diffusion for hematomas with intracellular blood products to be 0.3 x 10(-3) mm2/s.
Cerebral Hemorrhage↗
Optic neuritis: imaging with magnetization transfer.
OBJECTIVE: Our objective was to prospectively examine the optic nerves in patients with clinically severe unilateral optic neuritis, using routine spin-echo and magnetization transfer MR imaging. SUBJECTS AND METHODS: For 39 patients with such lesions, we calculated the magnetization transfer ratio along the involved intraorbital optic nerve and along the asymptomatic contralateral optic nerve in a mirror-image location. Magnetization transfer ratios were correlated with the imaging findings on routine spin-echo MR imaging. RESULTS: Magnetization transfer ratios were decreased in 33 of the 39 clinically symptomatic optic nerves, including 12 of the 18 clinically symptomatic optic nerves in which no abnormality was seen on routine spin-echo MR images obtained before and after administration of gadopentetate dimeglumine. CONCLUSION: Magnetization transfer imaging reveals intraorbital optic nerve abnormalities in patients with optic neuritis even when such lesions are otherwise occult on routine magnetization transfer imaging.
Adult↗
MRI findings of isolated beta-2 microglobulin amyloidosis presenting as a cervical spine mass. Case report and review of literature.
A patient without prior history of renal failure or hemodialysis presented with weakness of the extremities. On magnetic resonance imaging (MRI), a peri-odontoid soft-tissue mass hypointense to muscle on both T1- and T2-weighted images was noted without obvious bony destruction. Pathological examination revealed degenerated fibrocartilage which stained for amyloid. Further, peroxidase staining for beta-2 microglobulin was positive. We describe the first case of a beta-2 microglobulin peri-odontoid amyloidoma without preceding history of hemodialysis and a review of literature is performed.
Aged↗