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The Utility of Dual Energy CT Angiography in the Setting of Acute Ischemic Stroke

By: Raza Naqvi, Graeme Bell, Navdeep Sahota, Gage Watson, Prosanta Mondal, & Kyle Moulton

Purpose: Dual-energy CT angiography (DECTA) is a novel imaging application, in which dual-energy maps are acquired during the equilibrium phase of multiphase CTA (mCTA). The aim of this study is to assess the incremental utility of DECTA in predicting core infarct in the setting of mCTA evaluation of acute ischemic stroke (AIS) and large vessel occlusion (LVO).

Materials and Methods: Retrospective study of seventy consecutive patients who presented with LVO at a tertiary hospital between September 1, 2018 to October 31, 2019. DECTA images were acquired at 80 and 140 kV using a three-material decomposition algorithm during the equilibrium phase of CTA. The non-enhanced CT (NECT), NECT+DECTA, and follow-up CT/ MRI were independently reviewed by four readers and assigned Alberta Stroke Program Early CT scores (ASPECTS). Bland-Altman, sensitivity and specificity analyses, and Lin’s concordance were used to compare NECT and NECT+DECTA. Statistical analysis was performed using SAS, SPSS, and Stata.

Results: NECT+DECTA demonstrated more accurate detection of infarct core and prediction of final ASPECTS compared to NECT alone. Bland-Altman analyses indicated greater agreement between final infarct core and NECT+DECTA. Lin’s concordance correlation coefficients showed improved agreement between final infarct core and NECT+DECTA for all four readers [0.63 (0.51, 0.76) vs 0.44 (0.30, 0.58); 0.27 (0.15, 0.39) vs 0.20 (0.10, 0.31); 0.44 (0.31, 0.57) vs 0.25 (0.12, 0.37); 0.47 (0.31, 0.63) vs 0.34 (0.19, 0.49)]. NECT+DECTA showed improved sensitivity in detection of final ASPECTS for all four readers [70% vs 52%; 32% vs 25%; 39% vs 32%; 61% vs 39%]. Moderate inter-reader reliability was noted for NECT+DECTA [0.66 (0.47, 0.79)].

Conclusion: NECT+DECTA outperforms NECT alone in mCTA assessment of LVO through more accurate detection of infarct core and prediction of final ASPECTS. As such, the adoption of DECTA may improve patient selection for thrombectomy through improved identification of patients who are unlikely to benefit.

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