DeyeCOM(++) had 100% specificity for large vessel occlusion, whereas DeyeCOM(--) had a 100% specificity for absence of large vessel occlusion. Sustained DeyeCOM, whether positive or negative, is a strong predictor of ultimate diagnosis that could lead to quicker endovascular treatment times.

Introduction-The bolus tracking (BT) technique is the most popular PW DSC-MRI method used for estimating CBF, CBV and MTT. The BT technique uses a convolution model that establishes the input-output relationship between blood flow and the vascular tracer concentration. SVD (Singular Value Decomposition) and FT (Fourier Transform)-based methods are popular and widely used for estimating PW-MRI parameters. However, from the published literature it appears that SVD is more widely accepted than other method. In a previous article, an FT-based MMSE technique was proposed and simulation experiments were performed to compare it with the well established oSVD method. In this study, the FT-based MMSE method has been used to estimate relative CBF in 8 patients with white matter lesions (leukoaraiosis) and results are compared with the widely used circular SVD (oSVD) method.

Background: Identifying a last known well (LKW) time surrogate for acute stroke is vital to increase stroke treatment. Previous research have used an MRI DWI vs. FLAIR mismatch to estimate LKW time to within 6 hours. DWI signal intensity initially increases from onset of stroke, but mapping a reliable time course to the signal intensity has not been demonstrated. Methods: We retrospectively reviewed stroke code patients between 1/2016 and 6/2017 from the prospective, IRB approved UCSD Stroke Registry. Patients who had MRI brain from onset, with or without intervention, are included. All ischemic strokes were confirmed with ADC correlation and timing from onset to MRI was calculated. Raw DWI intensity was measured in grays (Gy) using IMPAX software and compared to contralateral side for control, for a relative DWI intensity (rDWI). LKW and MRI time were collected by chart review. Correlation was assessed using Pearson correlation coefficient between DWI intensity, rDWI, and time to MRI imaging. 1.5T, 3T, and combined modalities were examined. Results: 97 patients were included in this analysis. Overall, there is a good correlation (0.39, p<0.001) for minutes from onset to MRI and DWI intensity. There was good correlation with the 1.5T group (0.39, p=0.001) and very good correlation with the 3T group (0.60, p=0.001). There were no significant differences in demographic or time interval between the two MRI types. Conclusions: There is good correlation between DWI intensity and minutes from onset to MRI. This suggests a time-dependent DWI intensity response and supports the potential use of DWI intensity measurements to extrapolate a LKW time in unknown cases. Further studies in a larger dataset within the hyperacute period are being pursued to increase both experience and generalizability.

Background: Identification of large vessel occlusions (LVO) is important with recent guidelines supporting endovascular therapy in selected acute ischemic stroke patients. Many stroke centers perform CT angiography (CTA) in patients with suspected LVO; however this requires additional time and contrast administration. Non-enhanced CT maximum intensity projection (NECT-MIPs) may offer a rapid alternative to CTA.

Background: Identification of LVO is becoming increasingly important with recent guidelines supporting endovascular therapy in selected patients with acute ischemic stroke (AIS). Non-contrast CT scans are generally used to assess for stroke or hemorrhage in acute stroke code evaluations. CT angiograms (CTA) can be used to assess for LVO but require additional time and contrast administration. Some hospitals lack the resources to acutely obtain and interpret CTAs. Non-contrast CT MIPs may be an alternate modality to detect LVO. Methods: We retrospectively reviewed patients with AIS in our UCSD Stroke Registry, presenting between 6/2014-7/2016 that received a MIPs, generated from non-contrast CT scans, and a CTA. MIPs were evaluated by a group of stroke specialists (3 Faculty, 2 Fellows, 2 Acute Care Practitioners [ACPs]). No clinical information was provided. Gold standard comparison was to CTA. Results were stratified by subgroup based on level of training. Inter-rater agreement was assessed using Fleiss’ Kappa Coefficient. Results: 24 scans were reviewed (12 with LVO, 12 without LVO). Using MIPs for the detection of LVO, the Faculty subgroup had a sensitivity and specificity of 81% and 86% for any LVO, 95% and 92% for ICA/M1, 42% and 100% for M2 and 67% and 96% for basilar occlusions. The Fellows and ACPs subgroup had a sensitivity and specificity of 77% and 81% for any LVO, 61% and 94% for ICA/M1, 19% and 83% for M2 and 75% and 95% for basilar occlusions. Inter-rater agreement among Faculty readers was k=0.58 for the detection of any LVO, k=0.75 for ICA/M1, k=0.79 for M2 and k=0.14 for basilar occlusions. Among Fellows and ACPs, k=0.48 for any LVO, k=0.57 for ICA/M1, k=0.40 for M2, and k=0.27 for basilar occlusions. Conclusions: Non-contrast CT MIPs have high sensitivity and specificity for the detection of LVO when compared to CTA. Inter-rater agreement between readers of MIPs is good. Better results in the Faculty subgroup were likely due to more experience reviewing imaging. These results support the use of non-contrast CT MIPs for the detection of LVO to both save time and contrast exposure in patients with AIS. Further studies investigating a larger dataset, optimizing MIP parameters, and examining the utility/cost-effectiveness of this technique are being pursued.