Can CT perfusion accurately assess infarct core?

Abstract

Background: We sought to quantify CTP-derived infarct core applying previously published perfusion thresholds to multi-institutional CTP data to assess the margin of error for 25 mL and 70 mL critical volume thresholds using early DWI as a reference standard. Methods: 60 patients with acute ischemic stroke undergoing CTP and DWI within 6 and 24 h of symptom onset, respectively, were retrospectively analyzed from 3 tertiary care centers. CTP-derived infarct core was calculated using published thresholds for absolute and relative CBF and CBV in addition to manual CBV tracing. Using DWI as the reference standard, performance of CTP-derived measures of infarct core was assessed using co-registered voxel-by-voxel analysis and total infarct volume comparison. Volumes of each CTP infarct core estimate were compared against DWI to determine the degree of infarct core over or underestimation at the critical volumes of 25 mL and 70 mL. Results: Median core infarct volume was 10.8 mL. Mean CTP-derived infarct core volumes were similar to DWI for all CTP threshold methods to within ± 1 mL. CBV tracing demonstrated an overall significant core overestimation compared to DWI (p = 0.017). All CTP core volume estimations showed robust correlation with DWI (Pearson pvalue < 0.001). As core volume increased, CTP demonstrated increased deviation from DWI. At the critical cut-offs of 25 mL and 70 mL, relative CBF demonstrated the best agreement with DWI for infarct core compared to the other CTP-derived measures of infarct core. Conclusion: Our study demonstrates close approximation between multiple CTP-derived measures of infarct core and DWI infarct volume, Especially relative CBF.

Ischemic lesion growth in acute stroke: Water uptake quantification distinguishes between edema and tissue infarct

“…In 18 of 62 patients, the total infarct volume in the early FCT was lower than the volume of acute early infarct at admission as defined by rCBF threshold, which in the past has been claimed as an established method of defining the ischemic core lesion. 10,24,25,33 Thus, in our study, ischemic core volume measurements significantly overestimated the true ischemic core volume which emphasizes that the dogmatic application of perfusion thresholds to identify early infarct is likely incorrect when applied in patients with rapid endovascular recanalization as recently described by Bivard et al. 18,34,35 Similarly, Schaefer et al.…”

“…In 18 of 62 patients, the total infarct volume in the early FCT was lower than the volume of acute early infarct at admission as defined by rCBF threshold, which in the past has been claimed as an established method of defining the ischemic core lesion. 10,24,25,33 Thus, in our study, ischemic core volume measurements significantly overestimated the true ischemic core volume which emphasizes that the dogmatic application of perfusion thresholds to identify early infarct is likely incorrect when applied in patients with rapid endovascular recanalization as recently described by Bivard et al 18,34,35 Similarly, Schaefer et al described that in only 11/148 patients with acute ischemic stroke, infarct volume in FCT was smaller than the initial CTP-derived infarct core using cerebral blood volume. In our study, the effect of apparent overestimated core lesion by rCBF threshold was further aggravated when using edema-corrected infarct volume in early FCT (overestimated core lesion in 13/62 patients before and in 16/62 patients after edema correction, respectively).…”

“…The quantification of net infarct growth relied on the initial ischemic core, which was operationally defined using established rCBF threshold. 18,24,25 Previously validated thresholds for ischemic core in CTP may not be optimal in the setting of early and complete reperfusion. Future studies could use threshold-free algorithms for CTP analysis and improve measurement of infarct growth by edema-corrected lesion analysis.…”

“…any ischemic brain lesion with markedly decreased rCBF ( 30% compared to contralateral normal tissue) following published references. 8,18,[24][25][26] In the FCT, LV was captured by manual segmentation of the hypoattenuated infarct lesion using semiautomatic commercially available software (Analyze 11.0, Biomedical Imaging Resource, Mayo Clinic, Rochester, MN). The rater was blinded for all other imaging data and patient information in random order.…”

Deep learning guided stroke management: a review of clinical applications

“…Studies have shown that CTP is more sensitive than NCCT for identifying ischemic core,27 and can achieve close approximation to diffusion-weighted imaging, which is the gold standard 25. Although an estimate of the tissue at risk of ischemia can be made based on the site of vessel occlusion, accurate assessment is limited by the significant anatomical variability in collaterals, particularly in patients with a large ischemic core 28 29.…”