Introduction: Prior to surgical resection of arteriovenous malformations (AVMs), pre-operative embolization is primarily used to sequentially and gradually reduce flow in the AVM; the success in achieving this goal is primarily subjective through assessment of the angiographic runs pre and post embolization. We sought to directly measure the effects of embolization on AVM flow using Quantitative Magnetic Resonance Angiography (QMRA).
Methods: Medical charts, cerebral angiograms, and flow measurements were reviewed in patients with QMRA measurements of AVM flow pre and post embolization. Total AVM flow was calculated based on aggregate flow within the primary arterial feeders, or within draining veins. AVM flows were compared pre and post embolization. All sessions of embolization were performed with N-BCA glue except three sessions where Onyx was used.
Results: 51 AVM patients were evaluated with QMRA. Among those, 17 patients had flow measurements pre and post embolization. A total of 42 sessions of embolization were performed (range 1 to 6 per patient). Average AVM flow prior to treatment was 439cc/min (ranging 129- 952cc/min) in AVMs from 2.3-32 cc in size (median 6.4 cc). The median number of pedicles embolized per session was 3 (range 1-5). Flow dropped by a mean of 133 cc/min (range 14-410cc/min) per each session, representing an average 40% flow decline per session relative to flows immediately prior to the embolization. As compared to the baseline, there was an overall 67% (range 27-99%) reduction in AVM flow at the end of multiple sessions of embolization, with mean AVM flow dropping to 103cc/min (range 5-300cc/min) before the surgery. Interestingly, the number of pedicles embolized per session did not correlate with the flow drop.
Conclusions: Flow alterations induced by embolization can be quantified, and may provide a robust strategy to determine the number and efficacy of preoperative embolization sessions.
Patient Care: Both surgical resection and endovascular embolization are important tools in the treatment of arteriovenous malformations (AVMs). Adjuvant treatment with pre-operative embolization is utilized to reduce risk of intra-operative hemorrhage and mitigate the potential for bleeding related to 'normal perfusion breakthrough’ in the peri-operative period. A primary goal of the embolization is to sequentially and gradually reduce flow in the AVM; yet the extent of achieving this goal is purely subjective, and is non-quantitative. We do believe that through objective assessment of flow drops post embolization we would be able to select patients appropriately, and minimize need for further embolization. Thus offer safer treatment plans to patients with AVMs.
Learning Objectives: By the conculsion of this session, participants whoule be able to:
1)-Learn the role of flow measurments in AVM treatment.
2)- Learn to Quantitate AVM flow drop in AVM embolization