Capillary telangiectasias of the pons. Does diffusion-weighted MR increase diagnostic accuracy?

Capillary telangiectasias are benign lesions of the brainstem which are sometimes difficult to distinguish from other lesions in standard MRI. The purpose of this study was to evaluate if diffusion-weighted imaging (DWI) could help to improve diagnostic accuracy.

148 MR examinations of patients with pontine lesions were evaluated retrospectively and revealed capillary telangiectasia (n=18), presumed microvascular disease (n=20), encephalitis disseminata (n=21), pontine myelinolysis (n=16), tumor (n=20), acute infarction (n=20), subacute infarction (n=13) and chronic infarction (n=20). All patients were examined using identical measurement parameters for DWI, Fluid attenuated inversion recovery, T2-weighted turbo spin-echo, and T1-weighted spin-echo before and after application of contrast agent in transverse orientation.

All capillary telangiectasias showed low signal intensity in DWI and significant contrast enhancement after application of gadolinium. Hypointense signal on DWI was very rare for the remaining lesions: only 1 pontine myelinolysis, 1 tumor, 4 subacute infarctions, and 19 chronic infarctions also revealed low signal intensity on DWI. The combination of high signal intensity on T1-weighted post-contrast images and low signal intensity on DWI was found for all capillary telangiectasias, but only for 1/20 tumor and for 4/13 subacute infarctions. These lesions could be differentiated by their clinical course and/or MRI follow-up examinations. The results of the visual assessment were confirmed by quantitative evaluation.

DWI seems to be a useful adjunct for the diagnosis of capillary telangiectasias which will facilitate the differential diagnosis concerning tumorous, inflammatory and ischemic lesions.