Multiple hypointense vessels on susceptibility-weighted imaging in acute ischemic stroke: surrogate marker of oxygen extraction fraction in penumbra?

BACKGROUND: Multiple hypointense vessels (MHV) on susceptibility-weighted imaging (SWI) are frequently observed in patients with acute cerebral ischemia, but their implication has not been clearly established. To elucidate the clinical significance of MHV on SWI, we investigated the association of MHV on SWI with clinical data and other MR markers in patients with acute ischemic stroke. METHODS: We enrolled acute stroke patients with internal carotid or proximal middle cerebral artery occlusion who underwent MRI including SWI within 3 days from stroke onset. Baseline clinical data were reviewed. Stroke severity was measured by the National Institutes of Health Stroke Scale (NIHSS). We graded the degree of MHV on SWI as four groups of none, subtle, relative, or extensive by the modified Alberta Stroke Program Early CT Scan (ASPECTS) system. To evaluate the degree of collateral flow, distal hyperintense vessels (DHV) on FLAIR and vessels on post-contrast time-of-flight MR angiography (TOF MRA) source images were graded respectively as 3 groups: none/subtle/prominent and poor/moderate/good. Diffusion and perfusion lesion volume and diffusion-perfusion mismatch (DPM) ratio were measured in all patients. We analyzed the association of the degree of MHV on SWI with clinical data and MR markers. RESULTS: Eighty patients were included in the study. The mean MR time from stroke onset was 12.4 h (range 0.5-63.0). There is no difference in MR time from stroke onset between groups of MHV on SWI. MHV were observed in 68 (85%) of 80 patients: none in 12, subtle in 11, relative in 13, and extensive in 44. There were no statistically significant associations between MHV on SWI and vascular risk factors. Patients with more extensive MHV on SWI had a smaller diffusion volume (p < 0.001), larger DPM (p < 0.001), and lower initial NIHSS scores (p = 0.022). Prominent DHV was presented in 29 of 44 patients with extensive MHV (p < 0.001). Good collateral flow on TOF MRA source images was presented in 37 of 44 patients with extensive MHV (p < 0.001). CONCLUSIONS: More extensive MHV on SWI in acute ischemic stroke is associated with lower initial NIHSS scores, smaller diffusion lesion volume, better collateral flow, and larger DPM. Our results show the possibility that MHV on SWI may be a useful surrogate marker for predicting increased oxygen extraction fraction and diffusion-perfusion mismatch in acute ischemic hemisphere.

Spontaneous isolated posterior inferior cerebellar artery dissection: rare but underdiagnosed cause of ischemic stroke.

BACKGROUND: Spontaneous isolated posterior inferior cerebellar artery dissection (PICAD) is a very rare cause of ischemic stroke. Clinical and radiologic features of ischemic type of isolated spontaneous PICAD are not well established. METHODS: We consecutively enrolled patients who had spontaneous isolated PICAD confirmed by digital subtraction cerebral angiography. Clinical manifestation, magnetic resonance imaging (MRI), and angiography were analyzed. RESULTS: Seven patients were diagnosed as ischemic type of spontaneous isolated PICAD. Patients experienced an occipital headache, followed by vertigo, postural imbalance, or Wallenberg syndrome. Six showed medullar, unilateral, or bilateral cerebellar infarctions on diffusion-weighted imaging (DWI). One presented with transient cerebellar ischemia and negative on DWI. T1-weighted imaging showed high signal intensity in posterior inferior cerebellar artery in only 1 patient. Susceptibility-weighted imaging (SWI) revealed hypointense signal with blooming effect in posterior inferior cerebellar artery in 5 patients. The modified Rankin Scale score at 3 months was 0 or 1 in all patients. CONCLUSIONS: Clinical manifestations in ischemic type of spontaneous isolated PICAD were similar to those of intracranial vertebral artery dissection. Clinical course was relatively stable and benign. SWI was more helpful to suspect abnormality of posterior inferior cerebellar artery than conventional MRI or magnetic resonance angiography in our small series. Cerebral angiography is recommended in patients with clinically suspected spontaneous isolated PICAD for definite diagnosis.

Change in cortical vessel signs on susceptibility-weighted images after full recanalization in hyperacute ischemic stroke.

BACKGROUND: The cortical vessel signs (CVSs) on susceptibility-weighted images (SWIs) have been reported in patients with hyperacute ischemic stroke. We evaluated the change of this susceptibility sign on the immediate SWI after full recanalization and its clinical implications. METHODS: Nineteen hyperacute ischemic stroke patients who had acute large artery occlusion and underwent post-recanalization SWI were enrolled in this study. The patients had ICA (internal carotid artery, 2 cases), M1 (M1 segment of middle cerebral artery, 7 cases), M2 (M2 segment of middle cerebral artery, 1 cases), T (intracranial ICA bifurcation, 2 cases), ICA/M1 (4 cases) and basilar artery (3 cases) occlusion on imaging studies before thrombolysis and they underwent immediate magnetic resonance imaging, including the SWI, after full recanalization. The recanalization status was evaluated using the thrombolysis in cerebral infarction (TICI) score before and after thrombolysis. The SWI images were evaluated for the presence of asymmetry of veins over the ischemic territory and this was correlated with the site of stenosis or occlusion. The veins in the ischemic territory were classified as 'prominent' if there were more numerous veins and/or large veins with a greater signal loss observed compared with the opposite normal hemisphere, 'equal' if there were no significant difference in appearance in both the cerebral hemispheres, and 'less' if the veins were decreased in the affected area as compared with that of the normal cortex. Baseline clinical parameters and clinical outcomes were reviewed. RESULTS: The initial TICI grades were 0 in all cases. After thrombolysis, TICI grades were 3 in all cases. The pre-recanalization SWIs were obtained in 10 of 19 patients and all 10 showed prominent CVSs over the affected side, which disappeared on the post-recanalization SWI. On the post-recanalization SWI, the observed veins in the affected area were equal (10/19), less (5/19), and both equal and less (4/19). Patients with equal cortical veins in the affected area had small lesions on diffusion-weighted image (DWI) (10/19), while patients with less cortical veins had medium to large lesions on DWI (9/19). CONCLUSION: The prominent CVSs on SWI can be indicative of acute thromboembolic occlusion and its change immediately after recanalization can be used to reflect the metabolic status. After recanalization, the appearance of the equal CVS (return to normal) on SWI was associated with a favorable clinical outcome and infarction was avoided in our small series study.

Widespread cerebral cortical mineralization in Wilson's disease detected by susceptibility-weighted imaging.

Signal abnormalities of cortical gray matter, compared with the deep nuclear structures, have received less attention in Wilson's disease (WD). They nearly always accompanied white matter signal change, and commonly are associated with epilepsy and psychiatric features. We report herein two cases diagnosed as WD who, in addition to characteristic deep nuclear lesions on MR imaging, had widespread cerebral cortical paramagnetic signals dramatically detected by susceptibility-weighted imaging. T2-weighted MR images did not show any cortico-subcortical hyperintense lesions. To our knowledge, these findings have not been described before and may help to further characterize the disease.

Familial Creutzfeldt-Jakob disease with V180I mutation.

Creutzfeldt-Jakob disease (CJD) is an uncommon neurodegenerative disorder with an incidence of 1 per 1000,000 per year typically characterized by rapidly progressive dementia, ataxia, myoclonus and behavioral changes. Genetic prion diseases, which develop due to a mutations in the prion protein gene (PRNP), account for an estimated 10 to 15% of all CJD cases. We report a 75-yr-old woman with familial CJD carrying a V180I mutation which features late onset, slow progression, no periodic sharp wave complexes on electroencephalography, and extensive cortical ribboning with spared the cerebellum and the medial occipital lobes posterior to the parieto-occipital sulcus on MRI. To our knowledge, this is the first documented case of a point mutation at codon 180 in South Korea.