Faculty Bibliography

Purpose. The objective is to compare lateralizing ability of three quantitative MR (qMRI) modalities to depict changes of hippocampal architecture with clinical entities in temporal lobe epilepsy. Methods. We evaluated 14 patients with clinical and EEG proven diagnosis of unilateral TLE and 15 healthy volunteers. T1-weighted 3D dataset for volumetry, single-voxel ¹H MR spectroscopy (MRS), and diffusion tensor imaging (DTI) were performed for bilateral hippocampi of all subjects. Results. Individual volumetric measurements provided accurate lateralization in 85% of the patients, spectroscopy in 57%, and DTI in 57%. Higher lateralization ratios were acquired combining volumetry-spectroscopy (85%), spectroscopy-DTI (85%), and volumetry-DTI (100%). Significantly decreased NAA/(Cho+Cr) ratios (p = 0.002) and increased FA (p = 0.001) values were obtained in ipsilateral to epileptogenic hippocampus. Duration of epilepsy and FA values showed a significant negative correlation (p = 0.016, r = -0.847). The history of febrile convulsion associated with ipsilateral increased ADC values (p = 0.015, r = 0.851) and reduced NAA/(Cho+Cr) ratios (p = 0.047, r = -761). Conclusion. Volumetry, MRS, and DTI studies provide complementary information of hippocampal pathology. For lateralization of epileptogenic focus and preoperative examination, volumetry-DTI combination may be indicative of diagnostic accuracy.

OBJECTIVE: The objective of this study was to test the hypothesis that bitemporal hemianopsia (BHA) is the most common visual field (VF) defect in patients with pituitary macroadenoma and to assess the degree of optic pathway compression necessary to produce visual defects. MATERIALS AND METHODS: We reviewed the MRI findings and medical records of 119 patients with pituitary macroadenoma who had undergone formal assessment of VFs. We then evaluated the degree of optic pathway displacement caused by the pituitary macroadenoma, as observed on MR images. The classifications of optic pathway displacement included no contact, abutment but no displacement, mild displacement (< 3 mm), and moderate displacement (>/= 3 mm). Qualitative analysis classified VFs as normal or as having defects that were monocular, bitemporal, mixed (bitemporal with additional defects), homonymous, or nonspecific. RESULTS: A total of 89 of 115 patients had an abnormal VF. Only one patient had true BHA. The most common defects were bitemporal or mixed defects (in 49 of 115 patients [42.6%]), likely because more than just the chiasm is often compressed by the pituitary macroadenoma. Classification of optic pathway displacement by the pituitary macroadenoma was as follows: 23 patients had no contact, eight had abutment but no displacement, 27 had mild displacement, and 57 had moderate displacement. In 78 of the 92 patients (84.8%) with pituitary macroadenoma that had contact with the optic pathway, contact was with the optic chiasm and the prechiasmal optic nerve. Of the 49 patients with bitemporal or mixed defects, 42 had moderate displacement of the optic pathway caused by their tumors. CONCLUSION: BHA is exceedingly uncommon in patients with pituitary macroadenoma. However, although bitemporal and mixed defects are the most common abnormal VF findings, they were found in only 42.6% of patients. Such defects rarely occur if the tumor displaces the optic pathway less than 3 mm from baseline.

Neurofibromatosis bright objects (NBOs) are poorly understood. This article aimed to investigate: 1) differences in fractional anisotropy (FA) between NBOs based in gray matter (GM) and white matter (WM), and 2) the relationship between NBOs and the affected white matter tracts. Fourteen NF1 patients were included in this study. Apparent diffusion coefficient (ADC), FA, radial diffusivity (RD) and eigenvalues were used to compare NBOs and matching contralateral normal-appearing sites (NAS). Diffusion tensor imaging scalars were also compared with age-matched healthy controls. Fiber tractography was performed to assess NBO-induced changes in WM trajectories. ADC values were higher for GM and WM NBOs than for NAS and controls. FA values were lower in GM and WM NBOs compared with controls. In all regions, eigenvalues were higher in NBOs than in NAS and controls. Only three out of 18 NOBs appeared to disrupt WM tracts. ADC, lambda2 and RD values of WM NBOs were higher in symptomatic compared to asymptomatic patients. Increased ADC, RD and eigenvalues and decreased FA values in NBOs can be explained by myelin and axonal damage. Increased ADC values and RD in WM NBOs correlated with the presence of symptoms. Tract integrity predominated in our study.

The aim of this study was to determine various imaging features of intraosseous meningiomas (IOMs) and differentiate low-grade from high-grade tumors. The histopathologic evaluation revealed World Health Organization (WHO) grade I tumor in 56 (86%) patients, grade II in 8 (12%), and grade III in 1 (2%) patient. WHO grade I was considered low grade and II and III were designated as high grade. Hyperostosis was observed most commonly in low-grade IOMs. Mixed hyperostotic/lytic pattern with radial bony spiculations and presence of a scalp mass seem to be more frequently associated with higher-grade IOMs.

Hypoxic-ischemic injury (HII) continues to be an important cause of neonatal mortality and morbidity. In recent years, the role of magnetic resonance (MR) imaging has increased by providing early detection to initiate preventive measures and assess the severity of tissue injury, and it often serves as a prognostic indicator. However, because of the subtle findings and temporal variability of signal abnormalities, the imaging diagnosis often remains troublesome, particularly for trainees and general radiologists who do not often encounter these findings. The imaging manifestations between term and preterm infants differ significantly; the imaging findings in term neonates are discussed. Two main patterns of HII have been described in term neonates: peripheral and basal ganglia-thalamus, with the predominant pattern in an affected infant dependent on the duration and severity of the insult. The peripheral pattern occurs in the setting of mild hypoxia or ischemia of prolonged duration, with predominant findings in the cerebral cortex and subcortical white matter along the intervascular boundary zones. The basal ganglia-thalamus pattern is most often secondary to a more severe hypoxic or ischemic event of short duration and manifests with abnormal hyperintensity on T1-weighted images and hypointensity on T2-weighted images in the posterolateral putamen and ventrolateral thalamus. Associated loss of normal hyperintensity on T1-weighted images and hypointensity on T2-weighted images in the posterior limb of the internal capsule may be present. Restricted diffusion and evolution of imaging findings may be seen in each of these regions, depending on when images are obtained. Advanced imaging techniques, including MR spectroscopy, may add valuable information and specificity, with an abnormal lactate peak often serving as an indicator of HII in term neonates.

Vascular leiomyoma is a benign, usually solitary tumor arising from the tunica media of the vein. It can occur anywhere in the body wherever smooth muscle is present. These masses are commonly found in the uterus, urogenital tract and gastrointestinal tract but also less commonly in the extremities. They occur more often in the lower extremities than the upper extremities. Females are more affected than males and are generally seen in the third and fourth decades of life. We present magnetic resonance imaging, and histopathologic features of two pathology proven subcutaneous vascular leiomyomas of the hand and lower leg.

Intracranial hypotension syndrome (IHS) is a rare disorder characterized by postural headache, low cerebrospinal fluid (CSF) pressure, dural thickening and pachymeningeal contrast enhancement as a consequence of decreased CSF volume. The present report is a case of spontaneous IHS due to dural leak at the level of T12-L1. The site of CSF leakage was not detectable on either conventional magnetic resonance imaging (MRI) or T2-weighted MR myelography. However, it was evident on contrast-enhanced MR myelography (CE-MRM). The present report discusses the efficacy of CE-MRM in the detection of CSF leaks according to the literature so far.

BACKGROUND AND PURPOSE: Extracranial superficial temporal artery (STA) calcification is an unusual finding seen in patients with chronic kidney disease and has unknown ramifications with respect to intracranial ischemic disease. We sought to determine the association between the risk factors for vascular calcification and this rare phenomenon, in patients with chronic renal failure, and to assess the coexistence of cerebral ischemia. MATERIALS AND METHODS: Medical records and laboratory data on risk factors for vascular calcification were retrospectively retrieved for 453 patients with a discharge diagnosis of end-stage renal disease (ESRD). CT head examinations were reviewed to identify and associate STA calcification with 1) risk factors for the vascular calcification, 2) intracranial artery calcification, and 3) cerebral ischemia (white matter and/or cortical ischemic changes). RESULTS: STA calcification was present in 9.9% (45/453) of the studied cohort. The prevalence of cerebral ischemia was 24.4% (11/45) in patients with STA calcification and 9.3% (38/408) in patients without it. Diabetes mellitus (OR: 2.56, 95% CI: 1.059-6.208; P=0.037) was independently associated with the risk of STA calcification. The risk of cerebral ischemia, however, was not related to STA calcification (P=0.221). CONCLUSION: The presence of diabetes mellitus is important in describing the risk of STA calcification in patients with ESRD, whereas age, gender, hypertension, serum calcium, serum phosphate, or serum hemoglobin levels are not. The risk of cerebral ischemia is not related to STA calcification but has the strongest association with diabetes mellitus.