Miral Jhaveri

The utility of quantitative magnetic resonance angiography in the assessment of intracranial in-stent stenosis.

Background and Purpose— Noninvasive screening for intracranial in-stent stenosis is often limited by artifact because of the stent or associated coils. We aimed to determine the utility of quantitative MRA (QMRA) as a screening tool for detecting intracranial in-stent stenosis. Methods— We reviewed 14 patients who had intracranial stent placement with follow-up QMRA and conventional angiography at our institution. Socio-demographic, medical, clinical, and imaging data were abstracted from medical charts. A blinded interventional neurologist reviewed all angiograms for presence of >50% in-stent stenosis. We tested QMRA (mL/min) at varying thresholds as a predictor of angiographic results. Results— Among 14 patients (mean age, 62 years; 12 female, 2 male), 13 patients had Neuroform stents placed for wide-neck cerebral aneurysms and 1 patient had a Wingspan stent placement for atherosclerotic stenosis. Lesions were located in the intracranial internal carotid artery in 57.2% (n=8), the middle cerebral artery in 14.3% (n=2), and vertebrobasilar arteries in 28.6% (n=4). On follow-up angiography, 2 patients (14.3%) had >50% in-stent stenosis on angiography. Time-of-flight MRA was nondiagnostic in each case because of artifact from the stent or coils. A >20% reduction in vessel-specific blood flow by QMRA was associated with presence of >50% in-stent stenosis on angiography (P=0.033). As a screening tool to predict >50% angiographic in-stent stenosis, the sensitivity, specificity, positive predictive value, and negative predictive value of QMRA were 100%, 92%, 67%, and 100%, respectively. Conclusion— We found that QMRA is a promising screening tool to detect intracranial in-stent stenosis. Future prospective studies should focus on whether QMRA has a role in the detection of radiographic restenosis and prediction of clinical events.

Baseline differences between vascular cognitive impairment no dementia reverters and non-reverters

Background: The underlying factors of reversion from cognitive impairment to normal cognitive functioning in stroke are not well understood. We compare demographic, cognitive and imaging factors in Vascular Cognitive Impairment, No Dementia (Vascular CIND) patients who revert to normal cognitive functioning to Vascular CIND patients who do not revert. Methods: Thirty-one ischaemic stroke patients, who met classification criteria for Vascular CIND, were >49.5 years old, met NINDS stroke criteria, and were free from additional neurological illness, completed baseline and 1-year examinations. Forty-five per cent of the Vascular CIND participants reverted to no cognitive impairment at 1-year follow-up examination. Results: There was greater cognitive impairment in non-reverters on a summary score spanning several neuropsychological domains and on psychomotor and working memory summary scores. There were no differences on demographic factors or in stroke severity between reverters and non-reverters. Structural MRI analyses revealed no baseline differences in number of strokes, stroke volume or stroke location. However, there was greater frontal white matter hyperintensity load in the non-reverter group. Conclusions: These results suggest that Vascular CIND reversion may be a function of a combination of baseline neuropsychological function and location of cerebrovascular disease.

Evaluation of a Metal Artifacts Reduction Algorithm Applied to Postinterventional Flat Panel Detector CT Imaging

BACKGROUND AND PURPOSE: Flat panel detector CT images are degraded by streak artifacts caused by radiodense implanted materials such as coils or clips. A new metal artifacts reduction prototype algorithm has been used to minimize these artifacts. The application of this new metal artifacts reduction algorithm was evaluated for flat panel detector CT imaging performed in a routine clinical setting. MATERIALS AND METHODS: Flat panel detector CT images were obtained from 59 patients immediately following cerebral endovascular procedures or as surveillance imaging for cerebral endovascular or surgical procedures previously performed. The images were independently evaluated by 7 physicians for metal artifacts reduction on a 3-point scale at 2 locations: immediately adjacent to the metallic implant and 3 cm away from it. The number of visible vessels before and after metal artifacts reduction correction was also evaluated within a 3-cm radius around the metallic implant. RESULTS: The metal artifacts reduction algorithm was applied to the 59 flat panel detector CT datasets without complications. The metal artifacts in the reduction-corrected flat panel detector CT images were significantly reduced in the area immediately adjacent to the implanted metal object (P = .05) and in the area 3 cm away from the metal object (P = .03). The average number of visible vessel segments increased from 4.07 to 5.29 (P = .1235) after application of the metal artifacts reduction algorithm to the flat panel detector CT images. CONCLUSIONS: Metal artifacts reduction is an effective method to improve flat panel detector CT images degraded by metal artifacts. Metal artifacts are significantly decreased by the metal artifacts reduction algorithm, and there was a trend toward increased vessel-segment visualization.

Hemodynamic Changes Following Wingspan Stent Placement-A Quantitative Magnetic Resonance Angiography Study

Quantitative magnetic resonance angiography (QMRA) is a noninvasive imaging modality that provides anatomic and physiologic measurements of arteries. We used QMRA to assess hemodynamic changes following Wingspan stent placement for intracranial stenosis.

Minimally invasive evacuation of intraventricular hemorrhage with the Apollo vibration/suction device.

Intraventricular hemorrhages (IVH) can occur as a consequence of spontaneous intracerebral hemorrhage, aneurysm rupture, arteriovenous malformation hemorrhage, trauma, or coagulopathy. IVH is a known risk factor for poor clinical outcome with up to 80% mortality. The current standard treatment strategy for IVH consists of the placement of an external ventricular drain. We report our early experience with using the Apollo suction/vibration aspiration system (Penumbra, Alameda, CA, USA) for minimally invasive evacuation of IVH with a review of the pertinent literature. Medical records of patients with IVH who were admitted to Rush University Medical Center, USA, from July to November 2014 were queried from the electronic database. Patients with Graeb Scores (GS) >6 were selected for minimally invasive IVH evacuation with the Apollo aspiration system. Patient demographics, pre- and post-operative GS, pre- and post-operative modified Graeb Score (mGS), as well procedure related complications were analyzed and recorded. A total of eight patients (five men) were identified during the study period. The average age was 55.5years. The mean GS was 9.6 pre-operatively and decreased to 4.9 post-operatively (p=0.0002). The mean mGS was 22.9 pre-operatively and decreased to 11.4 post-operatively (p=0.0001). Most of the IVH reduction occurred in the frontal horn and atrium of the lateral ventricle, as well the third ventricle. One (1/8) procedure-related complication occurred consisted of a tract hemorrhage. The Apollo system can be used for minimally invasive IVH evacuation to achieve significant blood clot volume reduction with minimal procedure-related complication.

Restricted Diffusion on Magnetic Resonance Imaging in Partial Status Epilepticus

A N 82-YEAR-OLD WOManwithhypertension and bipolar disorder was admitted with new-onset generalized tonic-clonic seizures. On admission, magnetic resonance imaging (MRI) results were normal and electroencephalography showed right posterior quadrant slowing. She was started on valproic acid. One week later, she was found to have a left hemiparesis and 20 hours of continuous rhythmic jerks of the left leg, arm, and abdomen with retained consciousness, consistent with partial status epilepticus. Magnetic resonance imaging (Figure 1) showed restricted diffusion in the right parietal, occipital, and medial frontal cortices, with corresponding low signal on apparent diffusion coefficient maps. Magnetic resonance angiography results were normal. Electroencephalography (Figure 2) showed right posterior quadrant epileptiform activity that correlated with the area of restricted diffusion. The seizures and hemiparesis resolved after treatment with phenytoin and lorazepam. Repeat MRI 4 weeks later showed resolution of the diffusion abnormality and nearcomplete resolution of the hyperintensities seen on fluid-attenuated inversion recovery images. Transient imaging abnormalities on computed tomography and MRI as well as nuclide studies have previously been described in partial status epilepticus. Reversible hypodensities have been reported on computed tomography, whereas hyperintensities on T2-weighted imaging and restricted diffusion on MRI have been reported with prolonged seizures. These findings may be mistaken for ischemia in the acute setting. A clue that the restricted diffusion is due to the ictal process rather than acute infarction is the finding that the diffusion-weighted imaging abnormalities do not conform to a specific vascular territory. The diffusion abnormalities in status epilepticus are thought to represent cytotoxic edema but not underlying ischemia. The etiology of the cytotoxic edema is unclear. Proposed mechanisms include failure of the sodium-potassium ion adenosine triphosphate pump leading to an influx of sodium ions and water and increased anaerobic glycolysis.

MR imaging in nelarabine-induced myelopathy.

Nelarabine is one of the newer and novel drugs approved by the USA Food and Drug Administration for treatment of relapsed and resistant acute lymphoblastic leukemia. Although there are a few accounts of the neurologic toxicity of nelarabine in the oncological literature, it has never been discussed from a radiologic stand point to our knowledge. We describe a case of nelarabine-induced myelopathy and review the existing literature in an attempt to characterize the MRI features helpful in making an early diagnosis of this elusive entity.

Teaching NeuroImages: Numb chin syndrome in an edentulous patient

A 49-year-old woman presented with isolated chin hypoesthesia. She had no history of malignancy or systemic symptoms and has worn dentures for 24 years. Results of a neurologic examination were unremarkable except …

Compressive optic neuropathy secondary to a lateral rectus muscle dermoid cyst.

A 48-year-old man presented 2 weeks after sudden OS vision loss. On examination, the patient had decreased OS visual acuity, an ipsilateral afferent pupil defect, and proptosis. MRI of the orbit with and without gadolinium showed a large, enhancing heterogeneous mass extending to the orbital apex. Uncomplicated resection was performed and pathology was consistent with a dermoid cyst. Postoperatively, the patient had improved visual acuity and minimal lateral rectus dysfunction. There are only 4 reported cases of dermoid cysts located within the lateral rectus muscle, albeit this is the first case describing a compressive optic neuropathy in the setting of an orbital dermoid cyst.

Teaching NeuroImages: Remote cerebellar hemorrhage following resection of a supratentorial tumor

A 23-year-old man was admitted with blurred vision and headache. Ten years ago he was diagnosed with a left temporal pleomorphic xanthoastrocytoma; his last resection was 6 years ago. Current CT and MRI showed left temporal encephalomalacia; MRI also revealed incidental bilateral remote cerebellar hemorrhages (RCH) (figure). Called “remote” due to their distance from the surgical site, RCH are rare complications of supratentorial and spinal operations.1 Depending on extent, RCH may be symptomatic and diagnosed acutely on CT, or incidentally discovered as …