Radiology, Vol 202, 55-59, Copyright © 1997 by Radiological Society of North America
Orbital pseudotumors: value of short inversion time inversion-recovery MR imaging
C Asao, Y Korogi, A Hotta, O Shimomura, M Kitajima, A Negi and M Takahashi
Department of Radiology, Kumamoto University School of Medicine, Japan.
PURPOSE: To evaluate magnetic resonance (MR) signal intensities of orbital
pseudotumors on short inversion time inversion-recovery (STIR) images and
to predict the effect of treatment. MATERIALS AND METHODS: Sequential MR
examinations were performed in 17 patients with orbital pseudotumors,
before and after treatment. All patients underwent MR imaging with T1- and
T2-weighted spin-echo or fast spin-echo sequences, and STIR sequences with
two 0.5-T systems. Quantitatively and qualitatively, the differences in
signal intensities among three therapeutic response groups (good, mild, and
no responses) were analyzed for each pulse sequence. RESULTS:
Quantitatively, both contrast and contrast-to-noise ratio on STIR images
corresponded well to the results of response to therapy for all background
markers; contrast and contrast-to-noise ratio values in the good response
group were the largest, while those in the no response group were the
smallest (P < .0001). Qualitatively, the signal intensities of the
lesions in the good response group were interpreted as hyperintense to the
cerebral cortex in 14 (93%) or 11 (73%) of 15 lesions by two observers,
respectively, while in the no response group, both observers assessed 16
(89%) of 18 lesions as hypo- or isointense to the muscle (P < .0001).
CONCLUSION: STIR images showed a variety of signal intensities in the
lesions, and the signal intensities on the STIR images helped predict the
response to the therapy in orbital pseudotumors.
