Rationale and Objectives
This study determines the value of whole brain color-coded three-dimensional perfused blood volume (PBV) computed tomography (CT) for the visualization of the infarcted tissue in acute stroke patients.
Materials and Methods
Nonenhanced CT (NECT), perfusion CT (PCT), and CT angiography (CTA) in 48 patients with acute ischemic stroke were performed. Whole brain PBV was calculated from NECT and CTA data sets using commercial software. PBV slices in identical orientation to the PCT slices were reconstructed and the area of visual perfusion abnormality on PBV maps was measured. The infarct core in the corresponding PCT slices (CBV <2.0 mL/100 g) was measured automatically with commercial software. The ischemic area on PBV and the infarct core on quantitative PCT were compared using the Pearsons-R correlation coefficient. Significance was considered for P < .05.
Results
The quantitative PCT demonstrated a mean infarct core volume of 35.48 ± 32.17 cm 3 , whereas the volume of visual perfusion abnormality of the corresponding PBV slices was 37.16 ± 37.59 cm 3 . The perfusion abnormality in PBV was highly correlated with the infarct core of quantitative PCT for area per slice ( r = 0.933, P < .01) as well as volume ( r = 0.922, P < .01).
Conclusions
PBV can serve as surrogate marker corresponding to the infarct core in acute stroke with whole brain coverage.
Stroke is one of the major diseases resulting in death or permanent disability worldwide . In Western countries, the age adjusted incidence rate is about 180 per 100,000 per year . Most strokes are caused by acute cerebral ischemia from occlusion of a cerebral artery. Rapid diagnosis with exclusion of cerebral hemorrhage and identification of the extent of infarction is mandatory in today’s acute stroke management . Both computed tomography (CT) and magnetic resonance imaging, have been proven to meet these demands . Automated analysis software has proven to enhance detection and volumetric assessment of ischemic stroke in an animal magnetic resonance imaging model . However, CT is the most frequently used method in clinical routine because of its wide availability . The combination of nonenhanced CT (NECT) with perfusion CT (PCT) increases the detection rate of ischemia and allows a better estimation of the extent of infarction . From PCT data, several perfusion parameters as well as brain barrier permeability can be calculated. It has been shown that absolute cerebral blood volume thresholds (CBV) can differentiate infarcted from noninfarcted tissue . However, PCT has limited volume coverage of typically 2–4 cm . CT angiography (CTA), on the other hand, covers the entire brain using current CT scanner technology and is typically included in a state-of-the-art CT stroke protocol for vessel assessment . Besides the visualization of cerebral vasculature, hemodynamic information is included in CTA data as well . Commercial software can calculate perfused blood volume (PBV) maps by the subtraction of the NECT from the CTA data . In theory, the information in terms of infarcted tissue should be similar between PBV maps and CBV maps generated from PCT data.
The aim of this study was to assess whole brain color-coded three-dimensional PBV CT for the visualization of infarcted tissue in acute stroke patients. Therefore, the visual perfusion abnormality in PBV maps was compared with the infarct core determined by absolute CBV thresholds on dynamic PCT.
Materials and methods
Patients
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Imaging Protocol
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Postprocessing
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Image Analysis
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Statistics
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Results
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Table 1
Study Population
Women_n_ = 30 Men_n_ = 18 Mean age 74.7 ± 12.2 y Mean NIHSS score 11.40 ± 4.93 Time interval between OOS and imaging 3.3 ± 2.9 hours
NIHSS, National Institute of Health Stroke Scale; OOS, onset of symptoms.
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Discussion
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