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Since 2005, it has been known that mother-to-child transmission of the chikungunya virus is possible. Transmission generally occurs in the perinatal period. In the present study, we describe the brain lesions seen on MR imaging of 6 cases of perinatal chikungunya infection. Patients who underwent brain MR imaging in the acute phase presented with areas of restricted diffusion in the white matter, suggesting a perivascular distribution, whereas those in the subacute/late phase showed cystic lesions, also with a perivascular distribution, with or without brain atrophy. One patient also presented with scattered hemorrhages in the frontal and parietal lobes. Important differential diagnoses include rotavirus, Parechovirus, herpes simplex infection, and hypoxic-ischemic encephalopathy, depending on the disease phase.
Parkinson disease is related to neurodegeneration and iron deposition in the substantia nigra pars compacta and nigrosome 1. However, visualization of nigrosome 1 via MR imaging is poor owing to the bilateral asymmetry, regardless of whether it is healthy. We focused on the magic angle and susceptibility effect and evaluated the anatomic slant structure of nigrosome 1 by tilting subjects’ heads in the B0 direction.MATERIALS AND METHODS:
To investigate the effectiveness of the magic angle, we tilted the volunteers’ heads to the right and left in the B0 direction or not at all for evaluating correlations between the degree of head tilting and visualization of the right nigrosome 1 and left nigrosome 1 using 3D spoiled gradient-echo sequences with multiecho acquisitions. We evaluated the susceptibility of nigrosome 1 and the local field using quantitative susceptibility mapping to assess static magnetic field inhomogeneity.RESULTS:
The heads tilted to the right and left showed significantly higher contrasts of nigrosome 1 and the substantia nigra pars compacta than the nontilted heads. No significant differences were observed in the visualization and susceptibility between the right nigrosome 1 and left nigrosome 1 for each head tilt. The effect of the magic angle was remarkable in the nontilted heads. This finding was supported by quantitative susceptibility mapping because the anatomic slant structure of nigrosome 1 was coherent between the axis of nigrosome 1 and the magic angle.CONCLUSIONS:
The asymmetric visualization of nigrosome 1 is affected by the magic angle and susceptibility. The anatomic slant structure of nigrosome 1 causes these challenges in visualization.
Glomangiopericytoma is a rare sinonasal mesenchymal tumor of borderline or low malignant potential. We reviewed the CT and MR imaging findings of head and neck glomangiopericytoma via a retrospective case series study and systematic review. Our study revealed that glomangiopericytoma is a well-defined lobulated avidly enhancing soft-tissue mass with erosive bony remodeling that is most commonly found in the sinonasal cavity. Typically, it is hyperintense on T2-weighted images with vascular signal voids, has a high mean ADC value, and a wash-in and washout pattern on dynamic contrast-enhanced MR imaging. Although the CT findings are nonspecific, typical MR imaging findings, including those on the ADC map and dynamic contrast-enhanced MR imaging, may be helpful for differentiating glomangiopericytomas from other hypervascular tumors in the head and neck.
Abnormally decreased T2/T2 FLAIR signal can be seen on brain imaging of patients who are experiencing clinical or subclinical seizures and can be associated with various intracranial pathologies. We identified 29 such patients. The abnormal signal was unilateral in 75.9% of patients. It affected various lobes of the brain, but only in the anterior circulation. In 28 patients (96.6%), there was corresponding decreased signal on DWI. The ADC was normal in all cases. In 26 patients (89.7%), there was corresponding low signal on SWI/gradient recalled-echo; 44.8% of patients underwent contrast-enhanced scans, and there was no abnormal enhancement. Twenty-two (75.9%) patients had documented clinical seizures on the day of imaging. The most frequent concomitant pathology was a subdural hematoma. Electroencephalograms obtained within 24 hours of imaging were available in 65.5%. Findings of all of these electroencephalograms were abnormal, and these electroencephalogram changes were either localized to the area of the abnormal MR imaging signal (where the signal was unilateral) or were bilateral (where the MR imaging changes were bilateral). In summary, decreased white matter T2/T2 FLAIR signal changes can be seen in patients with remarkably similar clinical findings (particularly seizures). These changes are often correlated with abnormal electroencephalogram activity localized to the involved lobes.
Excessive use of neurovascular imaging studies such as Doppler ultrasound, CTA, MRA, and DSA adds cost to the evaluation of patients with new neurologic deficits. We sought to determine to what extent redundant neurovascular imaging is generated by radiologists’ recommendations and the agreement rates among modalities in this setting.MATERIALS AND METHODS:
The radiology reports of 300 consecutive patients admitted for acute stroke to determine the frequency of the following: 1) >1 neurovascular study performed, 2) recommendation for another study, 3) recommendation made by the radiologist, and 4) agreement rates among these redundant neurovascular imaging studies.RESULTS:
Among the 300 consecutive patients, 125 had redundant neurovascular imaging, accounting for 144 redundant studies. These included 75/125 redundant neurovascular imaging studies after MRA, 48/125 after CTA, and 2/125 after Doppler ultrasound. The radiologist recommended another vascular study in 22/125 (17.6%) patients; the rest of the recommendations were made by clinicians. The second study agreed with the first in 54.6% (12/22) of cases recommended by radiologists and 73.8% (76/103) recommended by clinicians (P value = .06). CTA agreed with MRA, carotid Doppler ultrasound, and DSA in 66.7%, 66.7%, and 55.6%, respectively. MRA agreed with Doppler ultrasound and DSA in 78.3% and 66.7%, respectively.CONCLUSIONS:
Of cases with redundant neurovascular imaging, most were generated by clinicians, but radiologists recommended redundant neurovascular imaging in 17.6% of patients; 81.8% occurred following MRA. Overall, most secondary studies (68.8%) confirmed the findings of the first study. Such low-value, same-result redundant neurovascular imaging was more common when clinicians ordered the studies (73.8%) than when radiologists ordered them (54.6%).