Clinical Use of Computed Tomographic Perfusion for the Diagnosis and Prediction of Lesion Growth in Acute Ischemic Stroke

Abstract

Background and Purpose CT perfusion (CTP) mapping in research centers correlates well with diffusion weighted imaging (DWI) lesions and may accurately differentiate the infarct core from ischemic penumbra. The value of CTP in real-world clinical practice has not been fully established. We investigated the yield of CTP– derived cerebral blood volume (CBV) and mean transient time (MTT) for the detection of cerebral ischemia and ischemic penumbra in a sample of acute ischemic stroke (AIS) patients. Methods We studied 165 patients with initial clinical symptoms suggestive of AIS. All patients had an initial non-contrast head CT, CT Perfusion (CTP), CT angiogram (CTA) and follow up brain MRI. The obtained perfusion images were used for image processing. CBV, MTT and DWI lesion volumes were visually estimated and manually traced. Statistical analysis was done using R-2.14.and SAS 9.1. Results All normal DWI sequences had normal CBV and MTT studies (N=89). Seventy-three patients had acute DWI lesions. CBV was abnormal in 23.3% and MTT was abnormal in 42.5% of these patients. There was a high specificity (91.8%)but poor sensitivity (40.0%) for MTT maps predicting positive DWI. Spearman correlation was significant between MTT and DWI lesions (ρ=0.66, p>0.0001) only for abnormal MTT and DWI lesions>0cc. CBV lesions did not correlate with final DWI. Conclusions In real-world use, acute imaging with CTP did not predict stroke or DWI lesions with sufficient accuracy. Our findings argue against the use of CTP for screening AIS patients until real-world implementations match the accuracy reported from specialized research centers.

Defining Ischemic Core in Acute Ischemic Stroke Using CT Perfusion: A Multiparametric Bayesian-Based Model

“…Although quantitative CTP has been used successfully for treatment selection of patients with AIS in a controlled environment of randomized clinical trials, its day-to-day use may still be challenging due to inconsistencies of the results that are reflected in the literature. 13,16,17,19,25,28,29 There are several barriers to effective implementation of CTP in acute stroke care, including differences in CT scanners and hardware, postprocessing methodology such as different software packages, and different deconvolution techniques for quantitative analysis. [30][31][32][33] One of the potential limitations of quantitative CTP is related to the inherently noisy nature of CTP data, which can affect postprocessing and result in erroneous calculation of the ischemic core.…”

“…Although recent application of quantitative CTP has shown promising results in the supervised and controlled environment of clinical trials, there remains variability and inconsistency in the accuracy of quantitative CTP data provided in routine daily practice. 13,[16][17][18][19][20] The Bayesian method is a robust probabilistic method that minimizes the effects of oscillation and high levels of noise during residue function estimation compared with other deconvolution methods. 21,22 The advantages of the Bayesian model to provide more accurate estimation of perfusion values and reduction of variability have been shown in experimental phantom studies 23,24 and also recently in a cohort of patients with AIS.…”

Intra-Arterial Thrombectomy: Does Invasive Treatment Lead to Better Outcomes than Intravenous Thrombolysis Alone?

“…With shorter acquisition times of less than 60 s, core and penumbral volumes may be misrepresented, as was noted in the Multicenter Randomized Clinical trial of Endovascular treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) [17]. Also, ischemic penumbra seen on CT perfusion may not correlate with final stroke volume seen on MRI, even when no intervention is undertaken, and the tissue would be expected to proceed to infarct [18]. Other limitations include heterogeneity of protocols used for image acquisition and visualization of the anterior circulation only [19].…”

Acute Stroke Imaging: Recent Updates

“…CBV also did not correlate with the DWI abnormalities. This study advocates against utilization of CTP in acute NVS [23]. …”