Time-of-flight magnetic resonance angiography for detection of postoperative recurrence in patients with chronic subdural hematoma

Purpose Chronic subdural hematoma (CSDH) is associated with postoperative recurrence. Although various factors are involved in postoperative recurrence of CSDH, blood flow, especially in the middle meningeal artery (MMA), is considered to play an important role. We investigated whether the degree of signal intensity (SI) of the MMA on time-of-flight magnetic resonance angiography (TOF MRA) and various clinical factors are involved in recurrence of CSDH. Methods The maximum SI of both MMAs was measured on TOF MRA images within 1 month before or after the initial surgery. Results In total, 185 patients (20 with and 165 without recurrence of CSDH) were included in the analysis. The SI ratio and dementia were significant predictors of recurrence of CSDH (SI ratio: odds ratio [95% confidence interval (CI)] = 1.71 [1.32, 2.22], p < 0.0001; dementia: odds ratio [95% CI] = 7.41 [1.83, 30.1], p = 0.005). The estimated regression coefficients in the final model were 6.14 for the SI ratio and 1.28 for dementia. The risk score was derived according to these regression coefficients as follows: score = 5 × SI ratio + 1 (dementia: yes). With a score of 5, the predicted probability of recurrence was 2% [95% CI 0.7, 5.7], whereas with scores of 8 and 10, the probability was 43.3% [27.0, 61.1] and 89.5% [65.7, 97.5], respectively, which increased the risk of recurrence. Conclusion Patients with an increased SI ratio of the affected MMA on TOF MRA who underwent surgery for CSDH were significantly more likely to experience recurrence.