Achieving comparable perfusion results across vendors. The next step in standardizing stroke care: a technical report

Abstract

BackgroundThe role of mechanical thrombectomy in acute ischemic stroke (AIS) has been further expanded by recent trials which relied on the results of CT perfusion (CTP) imaging. However, CTP parameters for ischemia and infarct can vary significantly across different vendors.MethodsWe compared the outcomes of the Siemens CTP software against the clinically validated RAPID software in 45 consecutive patients with suspected AIS. Both perfusion softwares initially processed images using vendor defined parameters for hypoperfusion and non-viable tissue. The software thresholds on the Siemens software were decrementally altered to see if concordant results between softwares could be attained.ResultsAt baseline settings, the mean values for core infarct and hypoperfusion were different (mean of 30/69 mL, respectively, for RAPID and 49/77 mL for Siemens). However, reducing the threshold values for the later software showed a concordance of values at a relative cerebral blood flow <20%, with resulting core infarct and hypoperfusion volumes at 31/69 mL, respectively, for the Siemens software. A Wilcoxon paired test showed no significant difference between the calculated core infarct and hypoperfusion values, both for the entire population as well as for the subgroup of patients with large vessel occlusion.ConclusionEquivalent CTP results between vendor softwares may be attainable by altering the thresholds for hypoperfused and non-viable tissue, despite differences in acquisition techniques, post-processing, and scanners.

Hypoperfusion Index Ratio as a Surrogate of Collateral Scoring on CT Angiogram in Large Vessel Stroke

“…or missing data (n = 26), 94 patients were enrolled in the final analysis (male/female: n = 59/36) ( Figure 1). The mean age was 72 (SD: 12.9, range: 30-94), and the median NIHSS score was 21 (IQR: [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. The occlusion sites were at the ICA (n = 23), M1 (n = 42) and M2 (n = 29).…”

“…This may result from the different algorithms of image processing and chosen parameters in different software packages. A study reported that the infarct core predicted by Syngo.via will meet good agreement with RAPID if changing the parameters to CBV < 1.2 mL/100 mL and applying an additional smoothing filter [ 12 ], while another study suggested that the predicted volume of the infarct core calculated by Syngo.via could be concordant with RAPID if the relative cerebral blood flow threshold is changed to <20% [ 25 ]. In the same study, when analyzed as a subgroup, in patients with LVOs (ICA and M1 occlusion), there was no statistically significant difference between the calculated values for the core and hypoperfusion volumes.…”

Assessment of a Bayesian Vitrea CT Perfusion Analysis to Predict Final Infarct and Penumbra Volumes in Patients with Acute Ischemic Stroke: A Comparison with RAPID

“…Investigations are necessary due to discrepancies in CTP thresholds across perfusion map calculation methods and vendors. 7 In particular, Vitrea software allows 3 predefined threshold settings, each using distinct combinations of perfusion maps and contralateral hemisphere thresholds, for infarct and penumbra quantification as well as user-defined ROIs to outline ischemic regions.…”

Effect of computed tomography perfusion post-processing algorithms on optimal threshold selection for final infarct volume prediction

“…[12][13][14][15] Calculation differences potentially result in discrepancies in perfusion maps, preventing a standard infarct and penumbra identification protocol from being implemented across all CTP software and vendors. 16 This can be dangerous to patients, as overestimating infarct can lead to exclusion from thrombectomy procedures and underestimating infarct can lead to reperfusion injuries. 17 Furthermore, this may lead to discrepancies when reporting data from multicenter studies.…”