Matthew Louis White MD, Presenter: Nothing to Disclose

Theresa Hahn MA, Abstract Co-Author: Nothing to Disclose

Yan Zhang MD, Abstract Co-Author: Nothing to Disclose

Francis J. Hahn MD, Abstract Co-Author: Nothing to Disclose

Since the PROPELLER technique over samples the center of k-space, the signal contrast of structures in the brain are likely increased when compared to a similar fast spin-echo technique. The changes in contrast of normal structures could result in misinterpretation as pathological abnormalities. The purpose of this study was to quantitatively assess if the PROPELLER T2-FLAIR sequence produces higher contrast values for normal brain structures than the Fast Spin-Echo T2-FLAIR technique.

Twenty-four patients (12 male, 12 female), average age 35, were studied on a 3.0T HDx MR (GE, Milwaukee, WI) unit using both axial PROPELLER T2-FLAIR and axial Fast Spin-Echo T2-FLAIR sequences. An 8-channel head coil was utilized. The signal intensities of the bilateral hippocampi, medial thalami, insular cortices, frontal cortices, and parietal cortices were measured. The contrast values were calculated by comparing the signal intensities of these structures to the adjacent white matter, or as in the case of the thalami, the anterior aspect of the thalami. The paired t-test was used to determine the statistical significance of the quantitative data.

The average contrast values for PROPELLER T2-FLAIR were significantly greater compared to Fast Spin-Echo T2-FLAIR of the hippocampi (0.36, 0.29, p<0.001), medial thalami(0.23, 0.17, p<0.001), insular cortices (0.55, 0.38, p<0.001) and frontal cortices (0.49, 0.39, p<0.001). However, there was no significant difference found in the parietal cortices (0.32, 0.29, p=0.101).

The PROPELLER T2-FLAIR sequence produces significantly greater contrast for some anatomical structures of the brain.

Radiologists need to know that these altered appearances seen with PROPELLER T2-FLAIR could mimic pathological abnormalities, such as hippocampal edema and Wernicke’s encephalopathy.

White, M, Hahn, T, Zhang, Y, Hahn, F, Does PROPELLER T2-weighted FLAIR MR Imaging at 3T Alter the Appearance of Normal Brain Structures?.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5011899.html