Comparison of 3 T MRI and CT for the measurement of visceral and subcutaneous adipose tissue in humans.

OBJECTIVE: CT is considered the gold standard imaging modality for measurement of visceral adipose tissue area. However, as CT imaging exposes subjects to ionising radiation, a comparable imaging technique without this exposure is desirable, such as MRI. Therefore, we compared the agreement of measures of visceral adipose tissue and subcutaneous adipose tissue area from single-slice images obtained at the umbilicus using a 3 T MRI scanner with single-slice images obtained via CT scan. METHODS: 64 images were obtained from 27 subjects who underwent MRI and CT scanning on the same day, after 10-12 hours of fasting. Visceral and subcutaneous adipose tissue depots were manually separated and quantified using a multimodality image-processing software program. RESULTS: We found good agreement between CT and MRI for the measurement of both visceral adipose tissue and subcutaneous adipose tissue. Bland-Altman difference analysis demonstrated a mean bias of -2.9% (as a portion of total abdominal area) for visceral adipose tissue and +0.4% for subcutaneous adipose tissue, as measured by MRI compared with CT. CONCLUSION: MRI is a safe, accurate and precise imaging modality for measuring both visceral and subcutaneous adipose tissue, making it a favourable alternative to CT for quantification of these adipose depots.

Investigating the neurobiological basis of cognitive rehabilitation therapy with fMRI.

The neurobiological changes occurring during cognitive rehabilitation therapy (CRT) have yet to be systematically studied. In the present study, functional magnetic resonance imaging (fMRI) was used to demonstrate brain plasticity in response to CRT (n = 5) following mild traumatic brain injury. Neuropsychological tests and two fMRI activation tasks, a visually guided saccades and a reading comprehension task, were employed pre- and post-CRT. CRT was used to systematically address the identified deficits in visual scanning and language processing. As hypothesized, changes in the pattern and extent of activation within expected neuroanatomical areas occurred post-CRT. Changes in fMRI activation are discussed for each subject and related to changes on neuropsychological measures. This study demonstrates how fMRI can illustrate the neurobiological mechanisms of recovery in individual subjects. The variability in subject responses to CRT supports the notion of tailoring rehabilitation strategies to each subject in order to optimize recovery following brain injury.