Parotid Warthin's tumor: novel MR imaging score as diagnostic indicator.

OBJECTIVES: Despite known characteristic radiologic and clinical features, differentiation between Warthin's tumor (WT) and other parotid tumors remains challenging. The purpose of this study was to more precisely assess the MR imaging features of WT and to develop a scoring system combining the most specific characteristics. METHODS: A total of 208 patients with parotid gland tumors and presurgical MRI were included. Tumors were divided into 5 histological subtypes, and different MRI features were compared between groups. An MRI scoring test was developed including MR parameters that contributed significantly in distinguishing WT from other tumors. RESULTS: The best MRI features for differentiating between WTs from other tumors included bilaterality (P = 0.002), multifocality (P < 0.001), ADC values <905.1 (P < 0.001), and high signal intensity on T1-W images (P < 0.001). Six or more points on the 14-point scoring MRI scale was associated with an area under the curve of 0.99 (Accuracy of 98%), while a cut-off value of 7 indicated 100% specificity and 100% positive predictive value. CONCLUSIONS: Ill-defined margins, low T1-W signal, and location in the upper 2/3 of the parotid gland excluded WTs in 100% of cases. The proposed scoring method allows WTs to be distinguished from other tumors with high accuracy.

Correlation of PET/CT and Brain MRI Findings in Human African Trypanosomiasis Encephalitis.

ABSTRACT: A 49-year-old woman from Cameroon presented with history of several months of worsening headache, lethargy, left arm weakness, and generalized lymphadenopathy. Brain MRI demonstrated multifocal signal abnormality and enhancement involving the bilateral basal ganglia and cerebral white matter. FDG PET/CT performed as part of lymphadenopathy evaluation demonstrated patchy areas of increased metabolic activity of the brain parenchyma. Human African trypanosomiasis or African sleeping sickness is a protozoan infection caused by Trypanosoma brucei gambiense transmitted by the tsetse fly in sub-Saharan Africa. It is important to recognize the signs and symptoms in nonendemic countries to facilitate early diagnosis and treatment.

Spine Anatomy Imaging: An Update.

Spinal MR imaging is excellent for identifying details of spinal anatomy, including intraspinal contents, neural foramina, joints, ligaments, intervertebral discs, and bone marrow. Cortical bony structures of the spine are better imaged using CT. Conventional and CT myelography is an alternative to MR imaging in those with contraindications to MR imaging or in evaluation of spinal cerebrospinal fluid leaks. Motion- and flow-related artifacts may occur during imaging and should not be mistaken for lesions. With advancements in MR imaging hardware and software, spinal MR imaging can expand its role in the delineation of normal and abnormal spinal anatomy.

Defining the ischemic penumbra using magnetic resonance oxygen metabolic index.

BACKGROUND AND PURPOSE: Penumbral biomarkers promise to individualize treatment windows in acute ischemic stroke. We used a novel magnetic resonance imaging approach that measures oxygen metabolic index (OMI), a parameter closely related to positron emission tomography-derived cerebral metabolic rate of oxygen utilization (CMRO2), to derive a pair of ischemic thresholds: (1) an irreversible-injury threshold that differentiates ischemic core from penumbra and (2) a reversible-injury threshold that differentiates penumbra from tissue not-at-risk for infarction. METHODS: Forty patients with acute ischemic stroke underwent magnetic resonance imaging at 3 time points after stroke onset: <4.5 hours (for OMI threshold derivation), 6 hours (to determine reperfusion status), and 1 month (for infarct probability determination). A dynamic susceptibility contrast method measured cerebral blood flow, and an asymmetrical spin echo sequence measured oxygen extraction fraction, to derive OMI (OMI=cerebral blood flow×oxygen extraction fraction). Putative ischemic threshold pairs were iteratively tested using a computation-intensive method to derive infarct probabilities in 3 tissue groups defined by the thresholds (core, penumbra, and not-at-risk tissue). An optimal threshold pair was chosen based on its ability to predict infarction in the core, reperfusion-dependent survival in the penumbra, and survival in not-at-risk tissue. The predictive abilities of the thresholds were then tested within the same cohort using a 10-fold cross-validation method. RESULTS: The optimal OMI ischemic thresholds were found to be 0.28 and 0.42 of normal values in the contralateral hemisphere. Using the 10-fold cross-validation method, median infarct probabilities were 90.6% for core, 89.7% for nonreperfused penumbra, 9.95% for reperfused penumbra, and 6.28% for not-at-risk tissue. CONCLUSIONS: OMI thresholds, derived using voxel-based, reperfusion-dependent infarct probabilities, delineated the ischemic penumbra with high predictive ability. These thresholds will require confirmation in an independent patient sample.