Invisible metallic microfiber in clothing presents unrecognized MRI risk for cutaneous burn.

SUMMARY: We report a case of a thermal burn that occurred during MR imaging likely caused by invisible silver-embedded microfibers in the fabric of an undershirt. As the prevalence of fabric containing nondetectable metallic microfiber increases in athletic and "tech" clothing, the importance of having patients change into safe facility-provided garments before MR imaging is emphasized.

Clinical stroke penumbra: use of National Institutes of Health stroke scale as a surrogate for CT perfusion in patient triage for intra-arterial middle cerebral artery stroke therapy.

BACKGROUND AND PURPOSE: CTP may help triage acute stroke patients for IAT, but requires additional contrast agent, radiation, and imaging time. Our aim was to determine whether clinical examination (NIHSS) with NCCT and CTA can substitute for CTP without significantly affecting IAT triage of patients with acute MCA stroke. MATERIALS AND METHODS: We reviewed NCCT, CTA, and CTP imaging performed within 8 hours of symptom onset in 36 patients presenting with MCA territory stroke (September 2007-October 2009). Two neuroradiologists reviewed, independently and by consensus, NCCT, CTA, and CTP (CTP group), and 2 different neuroradiologists blinded to CTP reviewed NCCT, CTA, and NIHSS (stroke scale group) to determine IAT eligibility: M1 or proximal M2 occlusion; infarct core <1/3 MCA territory; and ischemic penumbra >20% infarct core. The stroke scale group estimated infarct core from NCCT and CTA source images and ischemic penumbra from core size relative to NIHSS score and re-evaluated patients after unblinding to CTP. We computed intragroup and intergroup κ scores for IAT treatment recommendation and used the McNemar test to determine whether CTP significantly affected the stroke scale group's decisions. RESULTS: IAT was recommended in 16/36 (44%) and 17/36 (47%) patients by the CTP and stroke scale groups, respectively, with intragroup κ scores of 0.78 ± 0.11 versus 0.83 ± 0.09. The intergroup κ score was 0.83 ± 0.09. When unblinded to CTP, the stroke scale group revised 2/36 (5.6%) decisions, which was insignificant (P = .48, McNemar test). CONCLUSIONS: NIHSS interpreted with NCCT and CTA may be an effective substitute for CTP-derived measures in the IAT triage of patients with acute MCA stroke. Replacing CTP may potentially reduce radiation and contrast dose and time to treatment.

Incidence of extrinsic compression of the internal jugular vein in unselected patients undergoing CT angiography.

BACKGROUND AND PURPOSE: Little is known about how commonly the internal jugular vein is compressed by extrinsic structures in the upper neck. The purpose of this paper was to identify the frequency and cause of external compression of the superior segment of the internal jugular vein. MATERIALS AND METHODS: Retrospective review of CT angiograms of the neck was performed in 108 consecutive patients. Axial source images were evaluated for moderate (>50%) or severe (>80%) stenosis of the internal jugular vein on the basis of external compression. The cause of extrinsic compression was also recorded. In cases with stenosis, the presence of ipsilateral isoattenuated collateral veins was recorded and considered representative of collateral flow. RESULTS: Moderate stenosis was seen in 33.3% of right and 25.9% of left internal jugular veins. Severe stenosis was seen in 24.1% of right and 18.5% of left internal jugular veins. The most common causes of extrinsic compression included the styloid process and the posterior belly of the digastric muscle. In patients with severe internal jugular vein stenosis, 53.8% of right sides and 55% of left sides had associated condylar collaterals. CONCLUSIONS: Extrinsic compression of the superior segment of the internal jugular vein is a common finding in unselected patients, often caused by the styloid process or the posterior belly of the digastric muscle. Presence of severe stenosis is not universally associated with collateral formation.

Optimization of the safety and efficacy of interferon beta 1b and azathioprine combination therapy in multiple sclerosis.

We conducted an open-label pilot clinical trial to evaluate the safety and efficacy of adding oral azathioprine to the treatment regimen of 15 multiple sclerosis patients breaking through monotherapy with interferon beta-1b. There were no serious adverse events. Gastrointestinal side effects and leukopenia were the most common adverse events and limited dose escalation. There was a 65% reduction in the number of gadolinium-enhanced magnetic resonance imaging (MRI) lesions on combination therapy compared to the baseline values (P =0.003). A total WBC count less than 4800/mm3 was the best predictor of MRI response.

MRI of intracerebral hematoma: value of vasogenic edema ratio for predicting the cause.

We evaluated a method for quantifying vasogenic edema (VE) on MRI to identify brain hematomas caused by neoplasms. We performed a blinded review of 68 acute and subacute hematomas caused by neoplasms (22), hypertension or presumed amyloid angiopathy (27), or vascular malformations (19). The extent of vasogenic edema was quantified on an axial T2-weighted image using the VE ratio: the maximum width of high signal surrounding a hematoma and the mean diameter of the hematoma. Hematomas caused by neoplasm were associated with more vasogenic edema (mean VE ratio 104%+/-15%; mean VE width 2.4+/-0.7 cm) than non-neoplastic hematomas (mean VE ratio 37%+/-5%; P =0.001). When the width of VE was equal to or more half the diameter the hematoma (VE ratio 50%), the positive predictive value for tumor was 66%; when it was equal to or more than the diameter, the positive predictive value was 71%. All six hematomas with VE ratios > or = 150% were caused by neoplasm.

An open-label trial of combination therapy with interferon beta-1a and oral methotrexate in MS.

An open-label study was performed to evaluate the safety and efficacy of combination therapy with weekly oral methotrexate (20 mg) and interferon beta-1a (IFN beta-1a) in 15 patients with MS who had experienced exacerbations while receiving IFN beta monotherapy. Nausea was the only major side effect. A 44% reduction in the number of gadolinium-enhanced lesions seen on MRI scan was observed during combination therapy (p = 0.02). There was a trend toward fewer exacerbations. This combination therapy appears to be safe and well tolerated, and should be studied in a controlled trial.

MR imaging of pituitary adenomas after gamma knife stereotactic radiosurgery.

OBJECTIVE: The purpose of this study was to evaluate the response of pituitary adenomas to radiosurgery as manifested by changes in size and appearance on serial MR imaging. MATERIALS AND METHODS: Over a mean follow-up period of 36 months, changes in 44 pituitary adenomas were assessed on 147 enhanced MR imaging studies. Prior surgery had been performed in 36 tumors (82%). RESULTS: At the time of radiosurgery, mean tumor volume was 5.9 +/- 0.8 cm(3) (mean diameter, 2.2 cm). The mean reduction in volume at last follow-up was 41% (+/- 5%, p < 0.001), and a decrease in tumor volume of 25-100% was observed in 34 tumors (77%). Mean reduction in tumor volume at 6 months after radiosurgery was 9% (p = 0.095); at 1 year, 24% (p < 0.001); at 2 years, 34% (p < 0.001); at 3 years, 41% (p < 0.001); and at 4 years, 50% (p = 0.008). Six months after radiosurgery a slight and transient increase in size was observed in 21% of tumors. During follow-up, neither decreased contrast enhancement nor cyst development was associated with changes in tumor volume. CONCLUSION: Tumor control was observed for most pituitary adenomas after radiosurgery and occurred gradually over a period of several years. A small increase in tumor size might be observed in the first 6 months after radiosurgery. In most cases, reductions in tumor size were not accompanied by a change in contrast enhancement or cyst formation.

Diffusion-weighted MR imaging of rim-enhancing brain masses: is markedly decreased water diffusion specific for brain abscess?

OBJECTIVE: This retrospective study investigated the specificity of restricted water diffusion for the diagnosis of brain abscess. Two of five rim-enhancing brain masses with restricted water diffusion (apparent diffusion coefficient of 0.79 [10(-3) mm(2)/sec] or less) were brain abscesses, but diagnoses in the other cases were metastatic squamous cell carcinoma (two cases) and radiation necrosis. CONCLUSION: Although an important diagnostic sign, restricted water diffusion is not specific for brain abscess.

Preoperative planning with magnetic resonance imaging and computerized volume rendering in twin-to-twin transfusion syndrome.

Our purpose was to illustrate the feasibility of preoperative planning with magnetic resonance imaging, 3-dimensional reconstruction, and volume-rendering techniques in twin-to-twin transfusion syndrome treated by endoscopic laser ablation of communicating vessels. After ultrasonographic determination of the syndrome and the indications for intervention, 2 patients with an anterior placenta underwent magnetic resonance imaging without the need for maternal or fetal sedation. Raw image data were downloaded into a desktop computer and manipulated with 3-dimensional reconstruction, volume rendering, and surgical navigation software. In both patients a virtual rendering of the fetuses, placenta, and uterus could be manipulated to expose all sides, demonstrate the location of the intertwin membrane, and plan the point of entry and curve of the endoscopic instruments. Preoperative planning and virtual surgical navigation in fetal surgery are now possible, as a result of shorter magnetic resonance imaging acquisition times and volume-rendering software. In this manner an entire virtual endoscopic fetal operation can be performed and fine-tuned before the actual procedure is to take place.

Acute vertebrobasilar occlusion: treatment with high-dose intraarterial urokinase.

OBJECTIVE: The purpose of this study was to describe our successful experience with high-dose intraarterial urokinase therapy in treating acute, life-threatening vertebrobasilar occlusion. CONCLUSION: We successfully treated five patients with acute vertebrobasilar occlusion who presented up to 24 hr after the onset of symptoms. Higher doses of urokinase than are commonly reported in the literature were used in this series at a rapid infusion rate with a "pulse-spray" technique. The result was prompt thrombolysis and good clinical outcome.

Assessment of the value of MR imaging for examining patients with angiographically negative subarachnoid hemorrhage.

OBJECTIVE: Our goal was to assess the value of MR imaging to patient care in the setting of angiographically negative subarachnoid hemorrhage and to evaluate the potential of MR imaging for revealing the mechanism for idiopathic perimesencephalic subarachnoid hemorrhage. MATERIALS AND METHODS: We retrospectively reviewed 71 patients who presented with subarachnoid hemorrhage and in whom the results of a four-vessel cerebral arteriogram were negative, a CT scan showed no evidence of intraaxial hemorrhage, and MR imaging had been performed within 72 hr of presentation. MR imaging of the brain included sagittal spin-echo T1-weighted, turbo spin-echo proton density-weighted, T2-weighted, and axial T2-weighted gradient-echo sequences. MR imaging of the cervical spine, which was performed in 41 of the 71 patients, included sagittal spin-echo T1-weighted, turbo spin-echo proton density-weighted, T2-weighted, and axial T2-weighted gradient-echo sequences. RESULTS: Perimesencephalic subarachnoid hemorrhage was seen on CT in 25 patients; in four of these patients (16%), MR imaging revealed acute perforator territory infarction involving the caudate, putamen, or thalamus. In 26 other patients, nonperimesencephalic subarachnoid hemorrhage was revealed on CT; in two of these patients (8%), MR imaging showed the cause of the subarachnoid hemorrhage. By contrast, 20 patients had negative findings on CT scans but xanthochromic CSF on lumbar puncture; in two of these patients (10%), MR findings were interpreted as responsible for subarachnoid hemorrhage. CONCLUSION: MR imaging showed diagnostic value in patients with angiographically negative subarachnoid hemorrhage, revealing abnormalities in 14% of the 71 patients, and resulted in a significant change in patient treatment in 6% of the patients. MR imaging also revealed an association between perimesencephalic subarachnoid hemorrhage and infarcts involving the territory of perforating arteries at the base of the brain. This finding may provide insight into the pathogenesis of perimesencephalic subarachnoid hemorrhage.

Spinal epidural abscess: correlation between MRI findings and outcome.

Our purpose was to determine if specific MRI findings in spinal epidural abscess (SEA), at the time of diagnosis, are associated with the clinical outcome. The clinical records and MRI studies of 18 patients with SEA were reviewed and follow-up was obtained from the outpatient medical record, telephone interview, or both. The association between findings on contrast-enhanced MRI and clinical outcome (weakness, neck or back pain, and incomplete functional recovery) was evaluated. With univariate analysis, narrowing of 50% or more of the central spinal canal (P = 0.03), peripheral contrast-enhancement (P = 0.05), and abnormal spinal cord signal intensity (P = 0.05) were associated with weakness at follow-up. Persistent neck or back pain was associated with spinal canal narrowing (P = 0.02), peripheral contrast-enhancement (P = 0.02), and an abscess longer than 3 cm (P = 0.04) on MRI. Incomplete clinical recovery was associated with both abscess length (P = 0.01) and the severity of canal narrowing (P = 0.01). Abscess length, enhancement pattern, and severity of canal narrowing can be incorporated in a grading system that can be used to predict outcome.

Reduplicative paramnesia: longitudinal neurobehavioral and neuroimaging analysis.

Reduplicative paramnesia (RP) is a delusion in which the patient perceives familiar places, objects, or events to have been duplicated. The current case describes the development of RP in an 81-year-old male following a large right frontal lobe infarction. As the patient had been hospitalized previously with hemorrhagic contusions, neurologic, neuropsychological, and neuroimaging data were obtained both prior to and following RP onset. Psychophysiologic data were obtained following the development of the delusion. Both premorbidly and at follow-up, neuropsychological functioning was characterized by significant impairments of learning and memory and frontal-executive functions. Language and visuospatial skills and motor speed were intact both before and after RP onset. The case is described within the context of preexisting theories of RP, and it is surmised that the delusion is secondary to temporal-limbic-frontal dysfunction giving rise to a distorted sense of familiarity and impaired ability to resolve the delusion via reasoning.

A SPECT imaging study of MRI white matter hyperintensity in patients with degenerative dementia.

We investigated the correlation between cortical perfusion and white matter hyperintensities on magnetic resonance images (MRI) of patients with dementia. The study included 40 subjects, each of whom had undergone both MRI and single-photon emission computed tomography (SPECT) studies as part of their diagnostic evaluation for degenerative dementia. Two neuroradiologists rated the MRI films for severity of periventricular white matter changes on a 0-5 point scale and severity of subcortical white matter changes on a 0-4 point scale. Twelve regions of interest from association cortex were sampled for the semiquantitative analysis of SPECT images. No relationship was found between these global MRI ratings and semiquantitative or qualitative SPECT findings. Dementia severity as measured by the Mini-Mental State Examination and the Clinical Dementia Rating was significantly correlated with SPECT, whereas age was significantly correlated with MRI ratings, particularly in the periventricular regions. These data support the view that cortical SPECT abnormalities are not associated with global MRI abnormalities in the subcortical and periventricular regions of patients with a clinical picture of degenerative dementia.

Cavernous hemangioma of the liver: pathologic correlation with high-field MR imaging.

OBJECTIVE: MR imaging is used to characterize cavernous hemangiomas of the liver because these neoplasms have a long transverse relaxation time compared with normal liver parenchyma and other hepatic neoplasms. The purpose of this study was to correlate the pathologic findings of hemangiomas with their appearance on high-field MR images and with mean T2 relaxation time. MATERIALS AND METHODS: Tissue cores were obtained by percutaneous needle biopsy of 14 cavernous hemangiomas, ranging in size from 1.0 to 10.9 cm. Mean relaxation time was determined from T2-weighted spin-echo MR images. Pathologic analysis included quantification of endothelial cells, identified by counterstaining to anti-factor VIII antibody. RESULTS: We found an inverse relationship between the number of endothelial cells in the histologic specimen and the mean T2 value of the tumor (r = -.75; p < .002). Pathologic examination of tissue from three tumors with the shortest T2 relaxation times showed relatively greater amounts of connective tissue and more numerous but small and compressed vascular channels. Although the two hemangiomas less than 2 cm in diameter had T2 times less than 80 msec, no significant relationship between tumor size and relaxation time was found. CONCLUSION: We conclude that T2 relaxation time of cavernous hemangioma is directly related to the collective size of its constituent vascular spaces. We found no statistically significant difference in measured T2 relaxation time and no difference in histologic appearance between hemangiomas smaller than 2 cm and larger tumors.