Faculty Bibliography

OBJECTIVE: The purpose of this article is to address radiation necrosis, pseudoprogression, and pseudoresponse relative to high-grade gliomas and evaluate the role of conventional MRI and, in particular, dynamic susceptibility contrast-enhanced perfusion MRI in assessing such treatment-related changes from tumor recurrence. CONCLUSION: Posttreatment imaging assessment of high-grade gliomas remains challenging. Familiarity with the expected MR imaging appearances of treatment-related change and tumor recurrence will help distinguish these entities allowing appropriate management

OBJECTIVE: Large vestibular aqueduct syndrome (LVAS) is one of the most common anomalies of the inner ear. The purpose of our study was to evaluate the vestibule for associated aberrations. In particular, we assessed the vestibular volume in patients with LVAS, compared it to an age-matched control population, and evaluated the relationship between the size of the vestibular aqueduct and the vestibule. METHODS: We reviewed studies of high-resolution computed tomography of temporal bone of 24 consecutive patients with LVAS (15 girls and 9 boys; average age, 8.1 years). Of these, 21 patients had bilateral LVAS and 3 patients had unilateral LVAS. Each ear was evaluated for the size of the vestibular aqueduct and the volume of the vestibule. Similar measurements were obtained in an age-matched control population (28 girls and 18 boys; average age, 8.3 years). RESULTS: The volume of the vestibule was found to be significantly enlarged in patients with LVAS compared to the control population (right ear, P < 0.0001; left ear, P < 0.0001). A linear correlation could be established between an enlarged vestibular aqueduct and corresponding increase in the volume of the vestibule (right side, P < 0.01; left side, P < 0.01). CONCLUSION: A dilated dysplastic vestibule is a consistently associated finding in patients with LVAS

ABSTRACT: An aberrant subarcuate artery and its related canal are rare. The presence of this variation has a surgical significance, that is, risk of hemorrhage, if accidentally nicked. It is therefore important to be aware of this entity, and its relative anatomy, to avoid any untoward complication. We present a case of a 29-year-old man who presented with hearing loss after trauma. High-resolution computed tomographic scan of the temporal bone demonstrated an enlarged subarcuate canal

Acquired white matter abnormalities in children may be due to a broad spectrum of disorders, with the most significant related to metabolic and toxic etiologies. Recognition of the imaging appearance of neonatal hypoglycemia, nonketotic hyperglycemia, hyperammonemia, hepatic encephalopathy, and central pontine myelinolysis (CPM) is essential because prompt correction of the underlying metabolic abnormality may limit and, in some cases, reverse the cerebral damage. Toxic leukoencephalopathies encompass disorders caused by iatrogenic administration of pharmacologic agents and radiation therapy, poisoning by household substances, and recreational drug use. Although medication-induced leukoencephalopathies often show a propensity for reversibility of clinical and radiologic findings upon discontinuation of the offending substance, recreational drugs may cause white matter toxicity that often portends a poorer prognosis. Our discussion focuses on the clinical aspects, pathophysiological mechanisms, and imaging features of commonly encountered acquired metabolic and toxic leukoencephalopathies in the pediatric population.

OBJECTIVE: : Osteonecrosis of the jaws is recognized as a serious complication of biphosphonate therapy. The purpose of this study was to characterize the computed tomography (CT) imaging appearance of biphosphonate-associated osteonecrosis and to evaluate for distinguishing features of radiation-induced osteonecrosis (RION), osteomyelitis (OM), and metastases. METHODS: : We retrospectively reviewed CT scans of 6 patients with biopsy-proven biphosphonate-associated osteonecrosis (BAON). Computed tomographic scans were evaluated for presence of periosteal reaction, cortical erosion, reactive sclerosis, fragmentation and collapse of the underlying bone, destruction of the underlying trabecular bone manifested as radiolucency, sequestrum, and presence of any underlying bone expansion. Examinations were also assessed for presence of associated soft tissue mass. For comparison, we also retrospectively analyzed the CT scans of 5 patients with biopsy-proven RION of the jaw, 6 patients with OM, and 4 patients with metastases. RESULTS: : An expansile lytic lesion with dense central sequestrum likened to a 'bone-within-bone' appearance is highly suggestive of BAON. No RION or OM cases demonstrated an expansile lytic process. Instead, all the RION cases showed fragmentation and collapse of the underlying bone. Presence of cortical erosion, reactive sclerosis, radiolucency, and associated soft tissue mass should raise the possibility of OM in the appropriate clinical setting. CONCLUSIONS: : In an appropriate clinical setting, a bone-within-bone appearance should alert the clinician to the possibility of BAON

We present magnetic resonance (MR) imaging findings of the brain of a 6-year-old girl with fatal hemophagocytic syndrome (HPS); diffusion-weighted imaging shows abnormal intensity in the white matter and entire corpus callosum. HPS is a rare disorder that affects the mononuclear phagocyte system and not uncommonly involves the central nervous system. Various MR imaging findings of HPS have been reported, but restricted water diffusion throughout the entire corpus callosum lesion and lesions of the white matter have not been reported

PURPOSE: To compare diffusion weighted imaging metrics in gray and white matter brain regions of patients diagnosed with multiple sclerosis (MS) to those diagnosed with secondary demyelinating diseases such as neurosarcoid and acute disseminated encephalomyelitis (ADEM). MATERIALS AND METHODS: Diffusion weighted scans were performed and apparent diffusion coefficients of 12 regions of interest were determined in 30 MS patients, 21 neurosarcoid patients, and 4 ADEM patients. RESULTS: Mean apparent diffusion coefficients were significantly higher in MS patients than in non-MS patients in 6 of 6 of the corpus callosal regions assessed but not in any of the non-callosal white or gray matter regions assessed. CONCLUSION: Elevated apparent diffusion coefficients within the corpus callosum on diffusion weighted imaging may potentially help differentiate between patients with MS and patients with other diseases affecting the central nervous system white matter

BACKGROUND AND PURPOSE: Incidental positron-emission tomography (PET) uptake in the thyroid bed represents a diagnostic dilemma. Currently, there is no consensus regarding the significance of this finding or the most appropriate approach to management. The purpose of this study was to determine the significance of incidental fluorodeoxyglucose (FDG) uptake in the thyroid gland on [(18)F]FDG-positron-emission tomography (FDG-PET/CT) in patients being initially staged for lymphomas and/or cancers other than of thyroid origin. MATERIALS AND METHODS: A retrospective review was conducted on patients who were incidentally found to have focal FDG uptake in the thyroid bed on initial staging for cancer. Patient records were assessed for age, sex, clinical presentation, standard uptake values (SUV(max)), on FDG-PET/CT, and CT findings in those patients undergoing FDG-PET/CT, fine-needle aspiration (FNA) cytology, and surgical pathologic examination. RESULTS: Thirty patients were identified with incidental FDG-PET uptake in the thyroid bed from 630 studies performed for evaluation of cancer between March 2004 and June 2006. Complete records were available for 18 patients (6 men, 12 women). Five (27.8%) of 18 patients with incidental focal FDG-PET/CT uptake in the thyroid gland demonstrated papillary thyroid carcinoma on final pathologic findings. The mean and SD of SUV(max) was 3.0 +/- 1.8 (range, 1.1-7.4) overall, 2.9 +/- 1.6 (range, 1.1-6.8) in the patients without malignant growth, and 3.4 +/- 2.6 (range, 1.1-7.4) in the 5 patients with papillary thyroid carcinoma. No statistical difference in SUV(max) was noted between patients with papillary thyroid carcinoma and patients with benign pathologic findings (P = .63). CONCLUSIONS: Incidental FDG-PET uptake in the thyroid gland in patients with cancer of nonthyroidal origin is associated with a 27.8% risk for well-differentiated thyroid carcinoma; however, there seems to be no correlation between intensity of FDG uptake and the risk for a malignant process