Imaging finding and analysis of brain lymphoma in contrast-enhanced fluid attenuated inversion recovery sequence.

OBJECTIVE: The purpose of this retrospective study was to report and analyze the image findings of contrast-enhanced fluid-attenuated inversion recovery (CE-FLAIR) sequence of lymphoma in the brain. MATERIAL AND METHODS: Thirty-two immunocompetent patients with biopsy-proven diffuse large B-cell type lymphoma in the brain were evaluated with pre-treatment MRI examinations from August 2014 to April 2020. As stereotactic studies on the day of biopsy, FLAIR and T1-weighted axial images were acquired in 2 mm thickness, before and after administrating gadolinium-based contrast agents, with 3.0 Tesla MR machines. Respective subtraction images were also obtained for both CE-FLAIR and contrast-enhanced T1-wieghted image (CE-T1WI) sequences. The imaging findings, especially the enhancement pattern on CE-FLAIR sequence, were analyzed qualitatively and quantitatively, using semi-automatic segmentation. RESULTS: On CE-FLAIR images, brain lymphomas were poorly enhanced, while showing peripheral rim enhancement (54 of 58 lesions, 93.1 %) and central enhancing foci (40 of 58 lesions, 69.0 %). Seventy percent of central enhancing foci were correlated to areas with low signal intensity on CE-T1WI. In quantitative analysis, the mean signal intensity of CE-T1WI subtraction was 490.44 and that of FLAIR subtraction was 206.13. The standard deviation of all signal intensity values in CE-T1WI subtraction sequence was 143.45, while that of CE-FLAIR subtraction sequence was 118.41. CONCLUSION: On CE-FLAIR, brain lymphomas showed relatively poor and homogeneous enhancement, when compared to CE-T1WI. Most brain lymphomas displayed peripheral rim enhancement and central enhancing foci.

Prognostic CT findings of diplopia after surgical repair of pure orbital blowout fracture.

PURPOSE: Diplopia is a common sequela of blowout fracture even after proper surgical management. We investigated the prognostic factors of diplopia after surgery of pure blowout fracture. MATERIALS AND METHODS: We retrospectively reviewed CT images of 181 patients with pure orbital blowout fracture who underwent at least six months of postoperative follow-up. We evaluated the following CT factors: (1) fracture site (orbital floor, medial wall of the orbit, or both), (2) fracture type (closed flap, open flap), (3) fracture size, (4) volume of herniated orbital soft tissue, (5) ratio of volume of herniated orbital soft tissue to fracture size, (6) number of points of contact between extraocular muscle (EOM) and bony edge, (7) presence of EOM thickening, (8) EOM swelling ratio, (9) presence of displacement of EOM, (10) presence of deformity of EOM, (11) presence of tenting of EOM, and (12) presence of entrapment of EOM. The associations between diplopia at six months after surgical repair and various risk factors were analyzed using logistic regression models for univariable and multivariable analyses. RESULTS: EOM tenting and deformity and ratio of volume of herniated orbital soft tissue to fracture size were found to be statistically significant risk factors of diplopia at six months after repair on univariable analysis (all P < 0.05). Patients who showed EOM tenting or deformity on CT images had 5.22 and 10.85 times greater probability of diplopia after surgery, respectively (P-value, <0.001 and 0.026; 95% confidence interval of odds ratio, 2.071-13.174 and 1.323-88.915, respectively). On the other hand, ratio of volume of herniated orbital soft tissue to fracture size was not significant on multivariable analysis (P = 0.472). CONCLUSION: The prognosis of patients was predicted by CT evaluation. Patients who have tenting or deformity of EOM on CT scan are more likely to have postoperative diplopia.