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Angiography Suite Cone-Beam Computed Tomography Perfusion Imaging in Large-Vessel Occlusion Patients Using RAPID Software: A Pilot Study

Originally published 2021;52:e542–e544

Multidetector computed tomography (CT) perfusion (MDCTP) volume estimation using RAPID software (iSchemaView, Menlo Park, CA) has been validated in clinical trials for endovascular thrombectomy (EVT) selection.1,2 The availability of cone-beam CT perfusion (CBCTP) in the angiosuite might shorten workflow times in late-window patients transferred from primary centers without CTP capabilities. We evaluate whether quantitative analysis of MDCTP and CBCTP using RAPID software would lead to comparable ischemic core and hypoperfused tissue volumes in patients undergoing EVT.


Anonymized data are available upon reasonable request. This single-center study was approved by our Institutional Review Board and all participants/proxies signed a written informed consent form. We conducted a prospective, single-arm interventional study including patients with anterior circulation large-vessel occlusion stroke eligible for EVT. MDCTP and CBCTP datasets were processed using RAPID software (Data Supplement).

Ischemic core was defined as relative cerebral blood flow of <30% on MDCTP and <45% on CBCTP of the corresponding contralateral territory. The hypoperfused tissue was evaluated using time-to-maximum >6.0 s and time-to-maximum >10.0 s thresholds. We compared MDCTP and CBCTP volumes using intraclass correlation coefficient, Bland-Altman agreement plots, and Pearson and Spearman correlations. Finally, we compared CBCTP ischemic core and the final infarct volume in reperfused patients.


Thirteen patients were included in the final analysis (Figure I and Table I in the Data Supplement). We found a strong correlation between MDCTP and CBCTP for the ischemic core (Pearson=0.91, Spearman=0.87) and time-to-maximum >6.0 s (Pearson=0.90, Spearman=0.85). Bland-Altman analysis showed 92% agreement for both perfusion parameters (Figure). We observed an intraclass correlation coefficient of 0.89 (95% CI, 0.67–0.96) for the ischemic core and 0.86 (95% CI, 0.55–0.96) for time-to-maximum >6.0 s (Table II in the Data Supplement).


Figure. Ischemic core and hypoperfused tissue analysis. Scatterplot with regression line of relative cerebral blood flow (CBF) (A) and time-to-maximum (Tmax) >6.0 s (C) from multidetector computed tomography (CT) perfusion (MDCTP) and cone-beam CT perfusion (CBCTP). Bland-Altman plots comparing CBF (B) and Tmax>6.0 s (D) between MDCTP and CBCTP. Scatterplot with regression line and Bland-Altman plot comparing CBCTP ischemic core and final infarct volume in successful reperfusion patients. FIV indicates final infarct volume; and TICI, Thrombolysis in Cerebral Infarction.

Comparing CBCTP ischemic core and the final infarct volume, we found a strong correlation (Pearson=0.87, Spearman=0.87) and 90% of agreement. We also observed an intraclass correlation coefficient of 0.81 (95% CI, 0.48–0.94).


This study demonstrates that automated analysis of ischemic core and hypoperfused tissue volumes derived from MDCTP and CBCTP in patients with stroke eligible for EVT provides comparable results.

In our study, the contrast dose received in CBCTP after MDCTP was relatively low, and the median time between studies was short, which could reduce perfusion variations between modalities. Potential infarct growth between modalities was considered and 91% (10/11) of cases had concordant results using the DEFUSE 3 trial (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke) eligibility criteria for EVT.2

An automated real-time perfusion volumetric processing in the angiosuite would allow bypassing the emergency department for transferred large-vessel occlusion late-window patients. Thus, this technology might reduce reperfusion times and improve patients’ functional outcomes. In addition, CBCTP images could provide a more accurate assessment of perfusion parameters during and immediately after EVT. Downsides of transferring patients from primary centers to angiosuite might include EVT ineligibility due to large core infarct, low stroke severity, distal occlusion, among others.3

The study is limited by the small sample size. Additional limitations are included in the Data Supplement.

Nonstandard Abbreviations and Acronyms


cone-beam CT perfusion


computed tomography


endovascular thrombectomy


multidetector CT perfusion

Supplemental Materials

Expanded Methods, Results, and Discussion

Online Figure I

Online Tables I and II

Disclosures Dr Ortega-Gutierrez is consultant for Medtronic and Stryker. Dr Albers is consultant for Genentech, and ownership interest and consultant on the advisory board for iSchema View. Dr Schafer is employee of Siemens Healthineers. The other authors report no conflicts.


The Data Supplement is available with this article at

For Sources of Funding and Disclosures, see page e543.

Presented in part at the Society of Vascular and Interventional Neurology Annual Meeting, virtual, November 18–21, 2020, and the American Academy of Neurology Annual Meeting, virtual, April 17–22, 2021.

Correspondence to: Santiago Ortega-Gutierrez, MD, MSc, University of Iowa Hospitals and Clinics, 200 Hawkins Dr, Iowa City, IA 52242. Email


  • 1. Albers GW, Goyal M, Jahan R, Bonafe A, Diener HC, Levy EI, Pereira VM, Cognard C, Cohen DJ, Hacke W, et al. Ischemic core and hypoperfusion volumes predict infarct size in SWIFT PRIME.Ann Neurol. 2016; 79:76–89. doi: 10.1002/ana.24543CrossrefMedlineGoogle Scholar
  • 2. Albers GW, Marks MP, Kemp S, Christensen S, Tsai JP, Ortega-Gutierrez S, McTaggart RA, Torbey MT, Kim-Tenser M, Leslie-Mazwi T, et al; DEFUSE 3 Investigators. Thrombectomy for stroke at 6 to 16 hours with selection by perfusion imaging.N Engl J Med. 2018; 378:708–718. doi: 10.1056/NEJMoa1713973CrossrefMedlineGoogle Scholar
  • 3. Reddy ST, Savitz SI, Friedman E, Arevalo O, Zhang J, Ankrom C, Trevino A, Tzu-Ching W. Patients transferred within a telestroke network for large-vessel occlusion [published online September 20, 2020].J Telemed Telecare. 2020. doi: 1357633X20957894Google Scholar