Different CT perfusion algorithms in the detection of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage

Abstract

IntroductionTracer delay-sensitive perfusion algorithms in CT perfusion (CTP) result in an overestimation of the extent of ischemia in thromboembolic stroke. In diagnosing delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH), delayed arrival of contrast due to vasospasm may also overestimate the extent of ischemia. We investigated the diagnostic accuracy of tracer delay-sensitive and tracer delay-insensitive algorithms for detecting DCI.MethodsFrom a prospectively collected series of aSAH patients admitted between 2007–2011, we included patients with any clinical deterioration other than rebleeding within 21 days after SAH who underwent NCCT/CTP/CTA imaging. Causes of clinical deterioration were categorized into DCI and no DCI. CTP maps were calculated with tracer delay-sensitive and tracer delay-insensitive algorithms and were visually assessed for the presence of perfusion deficits by two independent observers with different levels of experience. The diagnostic value of both algorithms was calculated for both observers.ResultsSeventy-one patients were included. For the experienced observer, the positive predictive values (PPVs) were 0.67 for the delay-sensitive and 0.66 for the delay-insensitive algorithm, and the negative predictive values (NPVs) were 0.73 and 0.74. For the less experienced observer, PPVs were 0.60 for both algorithms, and NPVs were 0.66 for the delay-sensitive and 0.63 for the delay-insensitive algorithm.ConclusionTest characteristics are comparable for tracer delay-sensitive and tracer delay-insensitive algorithms for the visual assessment of CTP in diagnosing DCI. This indicates that both algorithms can be used for this purpose.

2023 Guideline for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage: A Guideline From the American Heart Association/American Stroke Association

“…Several diagnostic tools have been used to identify arterial narrowing and cerebral perfusion abnormalities that may help predict DCI. The most commonly available techniques include TCD ultrasound, 253,276–280 CTA and CTP, 270–275 and cEEG. 276,280–292 Other invasive methods include partial pressure of brain tissue oxygen (Pbt o 2 ), and cerebral microdialysis.…”

“…273 CTP has a positive predictive value of 0.67 for DCI. 271 In addition, CTP can be performed on day 3 after aSAH to assess patients at risk for DCI entering the vasospasm window, thus limiting the need for repeat studies, contrast, and radiation exposure. 272…”

Cerebral CT Perfusion in Acute Stroke: The Effect of Lowering the Tube Load and Sampling Rate on the Reproducibility of Parametric Maps

“…The lack of robust and freely accessible tools was the reason for implementing this technique and developing a new software tool. In addition, using commercial software from different vendors may introduce bias when compared to perfusion maps [ 17 , 18 , 19 ]. The software was based on the indicator dilution theory and the central volume principle, as firstly described by Meier and Ziegler [ 20 ].…”

Comparison of Accuracy of Arrival-Time-Insensitive and Arrival-Time-Sensitive CTP Algorithms for Prediction of Infarct Tissue Volumes

“…tandem occlusions, a stenosis upstream of the infarction, or suboptimal contrast enhancement of the scan [11][12][13] . As a consequence, ATS perfusion results may underestimate cerebral blood flow (CBF) and overestimate mean transit time (MTT), hence resulting in an overestimation of the ischemic core and an underestimation of the penumbra if CBF values in relation to the contralateral hemisphere (CBF_rel) are used [14][15][16] .…”