Ring-shaped lateral ventricular nodules: an incidental finding on brain magnetic resonance imaging.
BACKGROUND
We have occasionally seen ring-shaped lateral ventricular nodules <1 cm in diameter during routine brain magnetic resonance imaging (MRI). We investigated retrospectively clinical and MRI findings of the nodules.


METHODS
Review of radiological records was performed for 39,607 patients who underwent brain MRI between January 2001 and April 2008. Nodules were assessed for number, location, shape, and signal intensity, which was determined based on the range of signal intensity from gray to white matter on T1- and T2-weighted imaging. Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging (DWI), contrast enhancement characteristics, and serial MRI changes of nodules were assessed when available.


RESULTS
Nine of 39,607 patients (0.023%) showed the nodules. No symptoms associated with the nodules. Among the nine patients, 11 nodules were identified (one nodule in seven patients (77.8%) and two nodules in two patients (22.2%)). Location was limited to the roof of the body for six nodules (54.5%) and the frontal horn for five patients (45.5%). All nodules (100%) were round and isointense on T1- and T2-weighted imaging. On FLAIR imaging of eight nodules, six (75%) were hyperintense, and two (25%) were isointense. On DWI of seven nodules, all nodules (100%) were isointense. None of seven nodules (0%) examined using postcontrast MRI showed enhancement. None of eight nodules (0%) examined using serial MRI (range, 4-60 months) showed changes in morphology over time.


CONCLUSIONS
These nodules were incidentally encountered and shared similar MRI features. Although pathological confirmation was lacking in our cases, these nodules may be of nonaggressive nature.
Shimono
Taro
T
Department of Radiology, Kinki University School of Medicine, Osaka-Sayama, Osaka, Japan. shimono@med.kindai.ac.jp
Hosono
Makoto
M
Ashikaga
Ryuichiro
R
Kumano
Seishi
S
Imaoka
Izumi
I
Yagyu
Yukinobu
Y
Okada
Masahiro
M
Kuwabara
Masatomo
M
Murakami
Takamichi
T
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002551:Cerebral Ventricle Neoplasms / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D033162:Incidental Findings; D007564:Japan / Q000453:epidemiology; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged