P-019 Clinical significance of contrast staining after mechanical thrombectomy for acute ischemic stroke

gadolinium. Enhancement data variables from the MRI that were recorded included pattern (circumferential versus eccen-tric) and amount of maximal contrast enhancement based on region of interest differences in the region of highest T1 sig-nal between post and pre-contrast T1 sequences. Following thrombectomy, the type and number of passes with each device was recorded. Results 10 adult patients (6 F, Mean age of 65.7 years) were included in this study. Two received stent retriever with aspiration catheter, 7 received stent retriever only, and 1 received aspiration only. All 10 patients demonstrated circumferential enhancement in the region of retrieved clot, including the one patient who received aspiration only. Of the 9 patients that received the stent retriever, recanalization was achieved in 1 pass in 4, while in the other 5 patients, recanalization was achieved after multiple passes (range 2-4 passes). Dichot-omizing the data between 1 and multiple passes, there was a difference in the amount of mean maximal enhancement of the involved vessel wall (single pass: 75, Std Dev 28.39 vs multiple passes: 110.6, Std Dev 51.75), although this did not reach statistical significance due to a small number of patients. All patients showed circumferential wall enhancement despite type of thrombectomy technique, suggesting that all techniques may be associated with a similar mechanism of endothelial wall injury. Moreover, those patients who required multiple passes of the stent retriever for recanalization demonstrated a higher mean maximal enhancement when compared to those patients who required just one pass. Further explora-tion an increased number of patients is warranted.