Rasmussen's encephalitis: Proton MR spectroscopy and diffusion MR findings

Rasmussen's encephalitis is a chronic inflammation of the brain that leads to progressive neurologic deficits. The condition has previously been studi ed by various imaging modalities including MR imaging and MR spectroscopy. We studied three patients presenting with Rasmussen's encephalitis by using proton MR spectroscopy, and diffusion-weighted MR imaging. In these patien ts, on diffusion-weighted MR imaging, mean apparent diffusion coefficient ( ADC) value was 1.74 x 10(-3) mm(2)/sec within the parenchyma, apparently hi gher than that of the normal parenchyma (0.85 X 10(-3) mm(2)/sec) of a cont rol group of five healthy subjects. Proton MR spectra were obtained with a TR value of 1,500 msec and differing TE values (135, 40, and 20 msec), and were compared with a control group o f fourteen cases. In the affected regions of the brain, MR spectroscopy rev ealed decreased NAA, and increased Cho peaks associated with apparently dec reased NAA/Cho, NAA/Cr ratios, and increased Cho/Cr ratios. Slightly increa sed mi peaks, and increased mI/NAA ratios were noted. A prominent lactate p eak was noted in one of the patients.