Regional differences in diffusion tensor imaging measurements: assessment of intrarater and interrater variability.

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) has become a valuable tool in both the research and clinical evaluation of subjects. We sought to quantify interobserver and intraobserver variability of diffusivity and diffusion anisotropy measurements with regard to specific regions of interest (ROIs). MATERIALS AND METHODS: The subject group consisted of 5 healthy control subjects and 7 study subjects (all males; 16-19 years old; mean age = 17.5 years), as part of a protocol for closed head injury. Two whole-brain DTI scans were acquired on a 3T scanner for each subject. Analysis was performed using a ROI approach. Two independent observers analyzed the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) indices in the corpus callosum, cortical spinal tract, internal capsules (ICs), basal ganglia, and centrum semiovale (CSO). Intraobserver and interobserver variability were calculated for the mean ADC, FA, and ordered eigenvalues of the diffusion tensor (lambda(1), lambda(2), and lambda(3)). RESULTS: The overall kappa statistic for intraobserver variability for both observers showed slight-to-substantial agreement (kappa = 0.02-0.69), however FA values in the CSO showed only slight agreement. Interobserver agreement was also slight to substantial for these DTI measurements with high variability in FA values in the IC and CSO. CONCLUSIONS: When one is comparing 2 DTI measurements, it is important to assess intraobserver and interobserver variability. We recommend caution in the analysis of DTI contrasts in the IC and CSO, because we have found the widest range of variability in measurements within these structures.

Intraosseous lipoma of the left frontoethmoidal sinuses and nasal cavity.

Intraosseous lipomas are very rare slow-growing benign tumors that may appear as congenital lesions or may be acquired (metaplasia from a pre-existing lipoma). Only a handful of head and neck cases have been reported in the literature. We present the first reported case of a solitary osteolipoma involving the sinonasal tract in a 66-year-old man with sinonasal symptoms. CT showed a lesion involving the left frontal sinus, extending into the ethmoid sinus with insinuation along the left middle turbinate. It appeared to be an atypical mass with areas of high attenuation (calcification) within.

Imaging findings of a hibernoma of the neck.

Hibernoma is an uncommon benign fatty tumor that arises from the vestiges of fetal brown fat. We present a case report of a hibernoma of the neck in an asymptomatic 19-year-old girl and describe the important imaging findings. Computed tomography (CT) shows a well defined hypodense mass with septations. Magnetic resonance imaging (MRI) shows intermediate T1 and bright T2 signal of the mass and also demonstrates the characteristic marked contrast enhancement.