Ring-shaped lateral ventricular nodules detected with brain MR imaging

Abstract

Purpose: We evaluated the prevalence and imaging characteristics of ring-shaped lateral ventricular nodules (RSLVNs) detected by postcontrast brain magnetic resonance (MR) imaging. Materials and Methods: We retrospectively reviewed cranial MR images of 1,241 patients who underwent contrast-enhanced brain imaging between January 1, 2008 and March 31, 2011, excluded images of inadequate quality of 130 patients, and ultimately analyzed images of 1,111 patients (544 male, 567 female). We assessed location, shape, and signal intensity of RSLVNs on T1-weighted (T1WIs), T2-weighted (T2WIs), fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted (DWIs) images and characteristics of contrast enhancement. Results: In 5 patients, we found 6 RSLVNs (0.45%), four in the frontal horn and two in the roof of the body. Three RSLVNs were round, two were oval, and one was lobular on axial images. All 6 RSLVNs were isointense with adjacent brain parenchyma on T1WI, T2 WI, and DWI but slightly hyperintense on FLAIR images; none showed enhancement on postcontrast MR imaging. Five nodules serially examined (range, 8 to 24 months) showed no interval changes. Conclusions: Our MR imaging findings of a 0.45% prevalence of RSLVNs shows they are not so rare as previously reported. Except for configuration, all nodules had similar intensity, and none showed contrast enhancement. Absence of changes during the follow-up period seemed to indicate that the nodules have no clinical significance. However, their clear differentiation avoids unnecessary surgery. © 2013 Japanese Society for Magnetic Resonance in Medicine.