Faculty Bibliography

Objectives Typical FDG PET-CT imaging for oncology is performed from the base of the skull to the mid thighs. Both benign and malignant brain findings can occur in the oncology patient that would be missed on the typical PET scan. In our institution, when we perform whole body PET-MRI for cancer patients, we routinely include the entire head. In this retrospective study, we wished to characterize both PET and MRI brain findings that we encountered on the included head portion. Methods We retrospectively identified 192 FDG PET-MRI body imaging that included the head. Images were obtained on a dedicated PET-MRI camera with simultaneous acquisition. Images were obtained using a body coil without IV contrast and sequences were tailored for body pathology. Of these studies, there were 168 patients, 99 female and 69 male, in which we reviewed only the patient's first PET-MRI body studies acquired at our institution. The mean age of these 168 patients was 52 years with range 7-89. 156 studies were for cancer assessment with 62 staging and 94 restaging. The other 12 studies included 4 paraneoplastic evaluation, 3 adenopathy, 3 lung nodule evaluation, 1 vasculitis, and 1 IgG4 disease. Of the 12 studies, 3 were later diagnosed to have cancer. Images of the brain were reviewed by a neuroradiologist in conjunction with a nuclear radiologist. Lesions were characterized based on both MRI and PET findings. A chart review was performed. Results Of the 168 patients, 27 patients (16.1 %) had positive brain findings on PET-MRI body sequences. 10 (6.0%) had vascular disease (mean age 68 yrs) with 6 showing chronic microvascular ischemic changes and 4 had brain infarcts. One of the infarcts was a subacute stroke in a paraneoplastic patient. The average age of vascular disease was 68 yr with one newly discovered infarct in a 38 yr female. The detection rate for microvascular ischemic changes was likely lower due to the body MRI sequences. 6 patients had post therapy changes in the brain due to either radiation or surgery. There were 5 with benign lesions (mean age 41 yrs) include 2 perivascular space lesions, 2 probable chemotherapy changes, and 1 benign cystic mass. 6 had more serious brain pathologies including the 3 other paraneoplastic patients (leptomeningeal thickening with FDG cortical changes, metabolic encephalopathy, Creutzfeld-Jakob disease), 2 pituitary tumors, and 1 chronic subdural collection. Patients with more serious findings including the subacute infarct composed 4.2% with mean age 67 yrs. No incidental metastatic lesions were detected. Conclusions FDG PET-MRI imaging is a rapidly evolving modality that is most commonly employed for cancer evaluation. The standardized base of skull to mid thigh imaging may miss many important pathologies that are discovered even with MRI body sequences. We propose that PET-MRI body sequences that include the head may show added value in the management of patients

Ectopic craniopharyngioma is uncommon and a craniopharyngioma confined purely within the fourth ventricle is extremely rare. We report a craniopharyngioma of the fourth ventricle in a 20-year-old man with Gardner syndrome. Imaging characteristics of craniopharyngiomas and fourth ventricle lesions are discussed with a review of the literature regarding the pathogenesis of craniopharyngiomas and the possible association with Gardner syndrome.

OBJECTIVES: Contrast-enhanced fat-suppressed T1-weighted-2D-TSE and MPRAGE sequence with water excitation are routinely obtained to evaluate orbit pathology. However, these sequences can be marred by artifacts. The Radial-VIBE sequence is a motion-robust fat-suppressed T1W sequence which has demonstrated value in pediatric and body imaging. The purpose of our study is to evaluate its role in assessing the orbit, and to compare it with routinely acquired sequences. METHODS: A HIPAA-compliant and IRB-approved retrospective study was performed in 46 patients (age range: 1-81 years) who underwent orbit studies on a 1.5-T MRI using contrast-enhanced Radial-VIBE, MPRAGE and 2D-TSE sequences. Two radiologists blinded to the sequence analyzed evaluated multiple parameters of image quality including motion artifact, degree of fat-suppression, clarity of choroidal enhancement, intraorbital vessels, extraocular muscles, optic nerves, brain parenchyma and evaluation of pathology. Each parameter was assessed on a 5-point scale, with a higher score indicating the more optimal exam. Mix-model analysis of variance and interobserver variability were assessed. RESULTS: Radial-VIBE demonstrated superior quality (p<0.001) for all orbit parameters when compared to MPRAGE and 2D-TSE. Interobserver agreement demonstrated average fair-to -good agreement for: degree of motion artifact (0.745), fat suppression (0.678), clarity of choroidal enhancement (0.688), vessels (0.655), extraocular muscles (0.675), optic nerves (0.518), brain parenchyma (0.710), and evaluation of pathology (0.590). CONCLUSION: Radial-VIBE sequence demonstrates superior image quality when evaluating the orbits as compared to conventional MPRAGE and 2D-TSE sequences. Advances in knowledge: Radial-VIBE employs unique non-Cartesian k-space sampling in a radial or spoke-wheel fashion which provides superior image quality improving diagnostic capability in evaluation of the orbits.

BACKGROUND AND PURPOSE: The pituitary gland is located outside of the blood-brain barrier. Dynamic T1 weighted contrast enhanced sequence is considered to be the gold standard to evaluate this region. However, it does not allow assessment of intrinsic permeability properties of the gland. Our aim was to demonstrate the utility of radial volumetric interpolated brain examination with the golden-angle radial sparse parallel technique to evaluate permeability characteristics of the individual components (anterior and posterior gland and the median eminence) of the pituitary gland and areas of differential enhancement and to optimize the study acquisition time. MATERIALS AND METHODS: A retrospective study was performed in 52 patients (group 1, 25 patients with normal pituitary glands; and group 2, 27 patients with a known diagnosis of microadenoma). Radial volumetric interpolated brain examination sequences with golden-angle radial sparse parallel technique were evaluated with an ROI-based method to obtain signal-time curves and permeability measures of individual normal structures within the pituitary gland and areas of differential enhancement. Statistical analyses were performed to assess differences in the permeability parameters of these individual regions and optimize the study acquisition time. RESULTS: Signal-time curves from the posterior pituitary gland and median eminence demonstrated a faster wash-in and time of maximum enhancement with a lower peak of enhancement compared with the anterior pituitary gland (P < .005). Time-optimization analysis demonstrated that 120 seconds is ideal for dynamic pituitary gland evaluation. In the absence of a clinical history, differences in the signal-time curves allow easy distinction between a simple cyst and a microadenoma. CONCLUSIONS: This retrospective study confirms the ability of the golden-angle radial sparse parallel technique to evaluate the permeability characteristics of the pituitary gland and establishes 120 seconds as the ideal acquisition time for dynamic pituitary gland imaging.

Sarcoidosis is a granulomatous disorder of unknown etiology involving multiple organ systems. Isolated neurosarcoidosis is exceedingly rare. This case report presents isolated trigeminal nerve sarcoidosis mimicking schwannoma in a patient presenting with symptoms of trigeminal neuralgia. Neuroimaging revealed a mass associated with trigeminal nerve which prospectively thought to represent schwannoma. However, surgical pathology was consistent with sarcoidosis. Given great overlap in imaging characteristic of tumors in the Meckel's cave intraoperative frozen section biopsy may be considered to rule out an inflammatory lesion.

We report a case of a 37-year-old woman presenting with dysphagia and thyroid masses who was subsequently diagnosed with Lhermitte-Duclos disease (LDD) based on MRI scan and histopathology. Additional imaging subsequently revealed the presence of thyroid nodules and bilateral breast cancers. Genetic testing later confirmed the diagnosis of Cowden syndrome. This case illustrates the importance of the overlap between LDD, Cowden syndrome, thyroid disease, and breast cancer.