Intranidal signal distribution in post-contrast time-of-flight MRA is associated with rupture risk factors in arteriovenous malformations.

ABSTRACT

PURPOSE: To evaluate if arteriovenous malformations (AVMs) that are associated with a high rupture risk (HRR) are represented by different intranidal Time-of-Flight (TOF) magnetic resonance angiography intensity distributions compared to those with presumably low rupture risk (LRR). METHODS: Fifty post-contrast TOF datasets of patients with an AVM were analyzed in this study. The patients were classified to the HRR group in case of a deep location, presence of exclusive deep venous drainage, previous hemorrhagic event or a combination thereof. For each TOF dataset, the AVM nidus was semi-automatically delineated and used for histogram extraction. Each histogram was analyzed by calculating the skewness, kurtosis, mean and median intensity and full-width-half-maximum. Statistical analysis was performed using parameter-wise two-sided t-tests of the parameters between the two groups. RESULTS: Based on morphological analysis, 21 patients were classified to the HRR and 29 patients to the LRR group. Statistical analysis revealed that TOF intensity distributions of HRR AVMs exhibit a significant higher skewness (p=0.0005) parameter compared to LRR AVMs. Contrary to these findings, no significant differences were found for the other parameters evaluated. CONCLUSION: Intranidal flow heterogeneity, for example, caused by turbulent flow conditions, may play an important role for risk of a hemorrhage. An analysis of post-contrast TOF intensities within the nidus of an AVM may offer simple and valuable information for clinical risk estimation of AVMs and needs to be tested prospectively.