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Purpose: To assess the magnetic resonance imaging (MRI) findings, including diffusion-weighted imaging (DWI) in patients with acute carbon monoxide (CO) poisoning and correlate MRI findings with carboxyhemoglobin levels., Materials and Methods: The MRI examinations and medical records of seven men with a mean age of 43±16.0years (SD) (range: 25-63 years) with acute CO poisoning were reviewed. MRI examinations were analyzed with respect to lesion location, imaging presentation on T1- and T2-weighted images, and diffusion characteristics on DWI and apparent diffusion coefficient (ADC) maps. We also evaluated clinical features and laboratory findings including the presenting symptoms and signs, carboxyhemoglobin level, and treatment., Results: All seven patients presented with mental status change. The level of carboxyhemoglobin ranged between 8.3% and 34.8% (normal<1.5%). All seven patients (7/7, 100%) showed restricted diffusion of the lesions on ADC maps and bilateral involvement of globus pallidus. The mean ratios of ADC values was 0.63±0.15 (SD) (range: 0.46-0.92) on bilateral globi pallidi. Cerebral cortex, cerebral white matter, cerebellum, hippocampus, amygdala, splenium of corpus callosum, midbrain and insula were also involved., Conclusion: Bilateral globi pallidi with restricted diffusion may be a characteristic MRI feature in patients with acute CO poisoning. However, the relationship was not certain between the carboxyhemoglobin levels and the variety or severity of MRI findings., (Copyright © 2016 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.)

Background: Posterior reversible encephalopathy syndrome (PRES) is characterized by clinical symptoms that are associated with bilateral and symmetric vasogenic edema in the parietal and occipital lobes. However, this is rarely present with predominant involvement of the brain stem and cerebellum (variant)., Purpose: To evaluate which clinical or magnetic resonance imaging (MRI) findings can help to predict the prognosis of variant and classical type of PRES and whether or not there is difference between two types of PRES., Material and Methods: We retrospectively evaluated MRI and clinical findings from 49 patients with PRES. These patients were divided into two groups. In group I, patients had atypical distribution of lesions. In group II, patients had typical distribution of lesions. Follow-up MRI was performed on 26 patients. We assessed the MRI features, clinical data, and the patients' outcomes., Results: The mean blood pressure (BP) was significantly higher in group I (195.52/121.09 mmHg and 156.78/99.53 mmHg for groups I and II, respectively). The other factors assessed were not significantly different between the two groups. Lesions in 24 of 26 patients reversed upon follow-up. Sequelae were observed in 11 patients (group I, 7; group II, 4). However, there were no significant differences between the two groups. Except for those patients who died, seven of the nine patients with sequelae upon follow-up imaging had hemorrhage or irreversibility of lesions., Conclusion: Even though BP influences the involvement of the brain stem, involvement of the brain stem is not influential on the prognosis. It seems that the influential factor to prognosis is the reversibility of lesions and hemorrhage.

Purpose: To describe the magnetic resonance (MR) imaging features of six cases of pathologically proven fibrosing inflammatory pseudotumor involving the nasopharynx, and to compare the MR signal intensities of the lesions with histopathologic findings., Methods: We reviewed the MR finding of six patients with pathologically proved fibrosing inflammatory pseudotumor at the nasopharyngeal wall with respect to the following points: extent, margins, signal intensity and enhancement degree of the lesion; cervical lymphadenopathy and response to steroid therapy. MR findings were correlated with histopathologic findings., Results: All lesions showed ill-defined margins and looked less-likely contour bulging features. The signal intensity of the lesions was hypointense or slightly heterogeneous relative to brain cortex on both T1- and T2-weighted images, and enhancement was weakly homogeneous in all cases. There was no demonstrable cervical lymphadenopathy in all cases. After steroid therapy, the lesions showed decreased extent and weaker enhancement in three patients. Histopathologic findings showed high degree of polymorphous inflammatory cellular infiltration with underlying significant reactive fibrosis., Conclusion: Fibrotic inflammatory pseudotumors involving nasopharynx are very rare, and can mimic malignancy. MR imaging showed ill-defined margins, hypointensity or slightly heterogenous signal intensity on T2-weighted image and weak enhancement. There was no significant cervical lymphadenopathy.

Background and Purpose: The significance of postoperative nerve root changes (enhancement, thickening, and displacement) is still a topic of debate. The purpose of this study was to evaluate the association between nerve root changes and residual or recurrent symptoms after lumbar surgery with contrast-enhanced MR imaging., Materials and Methods: A total of 120 patients with 140 postoperative lumbar disk lesions causing residual or recurrent pain underwent contrast-enhanced MR imaging. The levels at which diskectomies had been performed were retrospectively evaluated for nerve root enhancement (NRE), thickening, and displacement. Association between nerve root changes and corresponding clinical presentations were statistically assessed. Nerve root changes in recurrent disk herniation (RDH) and postoperative epidural fibrosis (PEF) were also evaluated with clinical symptoms., Results: Ninety-two (65.7%) of the 140 disks demonstrated NRE. Regarding the association with clinical symptoms, the sensitivity was 91.7%, the specificity was 73.2%, the positive predictive value (PPV) was 83.7%, and the negative predictive value was 85.4% (P = .000). Nerve root thickening and displacement were significantly associated with the clinical symptoms, especially when NRE was combined (PPV, 87.7% and 87.2%, respectively). When RDH was combined with all 3 nerve root changes, the PPV was increased up to 94.1%. However, in PEF, the association between nerve root changes and clinical symptoms was not significant unless all 3 nerve root changes were combined., Conclusions: In patients with residual or recurrent pain after surgery for lumbar disk herniation, nerve root changes on contrast-enhanced MR imaging were well associated with clinical symptoms, of which NRE was the most significant finding.

The purpose of this prospective study was to determine whether using magnetic resonance imaging (MRI) for early screening for brain metastases (BM) can improve quality of life, survival in patients with non-small cell lung cancer (NSCLC). The study group comprised 183 patients newly diagnosed with NSCLC. All patients underwent limited brain MRI and routine workups. The control group comprised 131 patients with NSCLC who underwent limited brain MRI only if they had neurologic symptoms. The incidence of BM was 20.8% (38/183) in the study group and 4.6% (6/131) in the control group. The rate of upstaging based on the MRI data was 13.5% (15/111) overall and 15.9% (11/69) in patients that had been considered initially to be resectable surgically. There was no significant difference in survival outcome between the groups. Patients who had BM alone had a greater overall survival time (49 weeks) than those who had multiple systemic metastases (27 weeks; p=0.0307). In conclusions, limited brain MRI appears to be a useful, cost-effective method to screen for BM at the time of initial staging. And it may facilitate timely treatment of patients with NSCLC and improve their survival and quality of life.

Purpose: To determine the cause and frequency of high-signal-intensity foci detected in the insular cortex and extreme capsule on thin-section, high-spatial-resolution, coronal, T2-weighted magnetic resonance (MR) images., Materials and Methods: The authors assessed high-signal-intensity areas in the insular cortex and extreme capsule on coronal MR images obtained in 56 patients with seizure and five control subjects. Images were obtained with thin-section, high-spatial-resolution, T2-weighted, fast spin-echo; three-dimensional, spoiled gradient-recalled-echo; and fluid-attenuated inversion-recovery sequences. In two formalin-fixed brain specimens, MR imaging findings were correlated with gross anatomic and histologic findings., Results: Subinsular bright spots were found in 53 of the 56 (95%) patients (96 of 112 [86%] hemispheres) and all five control subjects. The spots were elliptical in 30 patients, round in 14 patients, linear in 22 patients, and dotlike in seven patients and often had a featherlike configuration. The spots were isointense to cerebrospinal fluid on T2-weighted, fast SE images and were located in the anterior extreme capsule white matter and insular cortex. MR imaging of brain specimens revealed bilateral elliptical areas of high signal intensity that corresponded to small multiple cavities at gross anatomic inspection. At microscopic examination, these cavities were perivascular spaces of mostly arteriolar origin., Conclusion: High-signal-intensity subinsular foci at MR imaging are due to enlarged perivascular spaces. In most cases, these foci can be visualized on thin-section, high-spatial-resolution, coronal T2-weighted images; they should not be mistaken for pathologic conditions when they occur unilaterally.