BACKGROUND AND PURPOSE: A hyperintense appearance of the dentate nucleus on T1-weighted MR images has been related to various clinical conditions, but the etiology remains indeterminate. We aimed to investigate the possible associations between a hyperintense appearance of the dentate nucleus on T1-weighted MR images in patients exposed to radiation and factors including, but not limited to, the cumulative number of contrast-enhanced MR images, amount of gadolinium administration, dosage of ionizing radiation, and patient demographics. MATERIALS AND METHODS: The medical records of 706 consecutive patients who were treated with brain irradiation at The Johns Hopkins Medical Institutions between 1995 and 2010 were blindly reviewed by 2 readers. RESULTS: One hundred eighty-four subjects were included for dentate nuclei analysis. Among the 184 subjects who cumulatively underwent 2677 MR imaging studies following intravenous gadolinium administration, 103 patients had hyperintense dentate nuclei on precontrast T1-weighted MR images. The average number of gadolinium-enhanced MR imaging studies performed in the group with normal dentate nuclei was significantly lower than that of the group with hyperintense dentate nuclei. The average follow-up time was 62.5 months. No significant difference was observed between hyperintense and normal dentate nuclei groups in terms of exposed radiation dose, serum creatinine and calcium/phosphate levels, patient demographics, history of chemotherapy, and strength of the scanner. No dentate nuclei abnormalities were found on the corresponding CT scans of patients with hyperintense dentate nuclei (n = 44). No dentate nuclei abnormalities were found in 53 healthy volunteers. CONCLUSIONS: Repeat performance of gadolinium-enhanced studies likely contributes to a long-standing hyperintense appearance of dentate nuclei on precontrast T1-weighted-MR images.

BACKGROUND AND PURPOSE: Loeys-Dietz syndrome (LDS) is a recently described entity that has the triad of arterial tortuosity and aneurysms, hypertelorism, and bifid uvula or cleft palate. Its neuroradiologic manifestations have not been well delineated. We sought to describe the neuroradiologic features of LDS and to assess the manifestations that would warrant follow-up imaging. MATERIALS AND METHODS: Two neuroradiologists retrospectively reviewed CT angiography (CTA), MR imaging, and plain film studies related to the head and neck in 25 patients ranging from 1 to 55 years of age, all of whom had positive genetic testing and clinical characteristics of LDS. Arterial tortuosity was evaluated by subjective assessment of 2D and 3D volumetric CTA and MR angiography data. Craniosynostosis and spinal manifestations were assessed by using plain films and CT images. MR images mostly of the head were reviewed for associated findings such as hydrocephalus, Chiari malformation, etc. Clinical manifestations were collated from the electronic patient record. RESULTS: All patients had extreme arterial tortuosity, which is characteristic of this syndrome. Thirteen patients had scoliosis, 12 had craniosynostosis, 8 had intracranial aneurysms, 6 had spinal instability, 3 had dissections of the carotid and vertebrobasilar arteries, 3 had hydrocephalus, 4 had dural ectasia, 2 had a Chiari malformation, and 1 had intracranial hemorrhage as a complication of vascular dissection. CONCLUSIONS: Significant neuroradiologic manifestations are associated with LDS, predominantly arterial tortuosity. Most of the patients in this series were young and, therefore, may require serial CTA monitoring for development of intra- and extracranial dissections and aneurysms, on the basis of the fact that most of the patients with pseudoaneurysms and dissection were older at the time of imaging. Other findings of LDS such as craniosynostosis, Chiari malformation, and spinal instability may also need to be addressed.

BACKGROUND AND PURPOSE: Tumors of pineal cell origin have different prognosis and treatment than those of germ cell origin. The recent literature suggests that these tumors often look alike. Our study aimed to differentiate between pineal cell tumor and germinoma based on ADC values, the homogeneity of the mass, and MR imaging characteristics. MATERIALS AND METHODS: We enrolled 20 patients who had pretreatment MR imaging scans with histologic verification of tumors of pineal cell origin and germinomas. The tumors were measured for the ADC values and for homogeneity by the coefficient of variation of ADC values, and T1WI and T2WI signal intensity values. RESULTS: The 20 subjects (8 females and 12 males) ranged in age from 1.5–64.9 years, with a mean age of 23.9 years (SD 17.7 years). The mean age of those with germinomas was 13.7 years (SD 3.8 years), less than the mean of 29.4 years for those with pineal cell tumors (SD 19.9 years; P = .016). These 2 groups showed no significant difference in coefficients of variation on T1WI, T2WI, and ADC images. However, germinomas showed statistically significant higher ADC values (mean 1590.69 ± 532.96 × 10⁻⁶ mm²/s) than pineal cell tumors (mean 883.58 ± 317.48 × 10⁻⁶ mm²/s; P = .02). An accuracy of 89.5%, sensitivity of 83.3%, specificity of 92.3%, PPV of 83.3%, and NPV of 92.3% were yielded for an ADC threshold of 1250.00 × 10⁻⁶ mm²/s. CONCLUSIONS: Germinomas showed higher ADC values than the pineal cell tumors (P = .02), and the patients were younger. Otherwise, there were no definitive imaging characteristics that distinguished pineal cell tumors from germinomas.

In this review article we have consolidated the imaging literature of patients with schizophrenia across the full spectrum of modalities in radiology including computed tomography (CT), morphologic magnetic resonance imaging (MRI), functional magnetic resonance imaging (fMRI), magnetic resonance spectroscopy (MRS), positron emission tomography (PET), and magnetoencephalography (MEG). We look at the impact of various subtypes of schizophrenia on imaging findings and the changes that occur with medical and transcranial magnetic stimulation (TMS) therapy. Our goal was a comprehensive multimodality summary of the findings of state-of-the-art imaging in untreated and treated patients with schizophrenia. Clinical imaging in schizophrenia is used to exclude structural lesions which may produce symptoms that may mimic those of patients with schizophrenia. Nonetheless one finds global volume loss in the brains of patients with schizophrenia with associated increased cerebrospinal fluid (CSF) volume and decreased gray matter volume. These features may be influenced by the duration of disease and or medication use. For functional studies, be they fluorodeoxyglucose positron emission tomography (FDG PET), rs-fMRI, task-based fMRI, diffusion tensor imaging (DTI) or MEG there generally is hypoactivation and disconnection between brain regions. However, these findings may vary depending upon the negative or positive symptomatology manifested in the patients. MR spectroscopy generally shows low N-acetylaspartate from neuronal loss and low glutamine (a neuroexcitatory marker) but glutathione may be elevated, particularly in non-treatment responders. The literature in schizophrenia is difficult to evaluate because age, gender, symptomatology, comorbidities, therapy use, disease duration, substance abuse, and coexisting other psychiatric disorders have not been adequately controlled for, even in large studies and meta-analyses.