Visual Grading System for Vasospasm Based on Perfusion CT Imaging: Comparisons with Conventional Angiography and Quantitative Perfusion CT
ABSTRACT The purpose of this study was to compare simple visual grading of perfusion CT (PCT) maps to a more quantitative, threshold-based interpretation of PCT parameters in the characterization of presence and severity of vasospasm.
Thirty-three patients with acute subarachnoid hemorrhage were enrolled in a prospective study and underwent a total of 40 paired PCT and digital subtraction angiography (DSA) examinations. A neuroradiologist and a neurologist reviewed the PCT mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume maps independently; they evaluated five anatomical regions (frontal, temporal, parietal, occipital/thalami, and basal ganglia/insula) and graded them for abnormality (0 if normal, 1 if abnormal in <50% of the region, and 2 if abnormal in >or=50% of the region). A third neuroradiologist blinded to the PCT results reviewed the DSA examinations and assessed 19 segments for the presence or absence of vasospasm. Correlation between PCT and DSA scores was assessed, as well as the sensitivity and specificity of PCT compared to DSA used as a gold standard.
MTT (R(2) = 0.939) and CBF (R(2) = 0.907) scores correlated best with DSA scores (p < 0.001). MTT scoring had a sensitivity of 92% and a specificity of 86% compared to DSA; CBF scoring had a sensitivity of 75% and a specificity of 95%. The interobserver agreement between neuroradiologist and neurologist was found to have kappa = 0.789 for MTT and 0.658 for CBF.
We propose a user-friendly visual grading system for PCT maps in patients with suspected vasospasm. This visual approach compares favorably to the results of DSA. Sensitive MTT maps should be used for screening, and specific CBF maps for confirmation of vasospasm.
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Article: Vasospasm and delayed consequences.Interventional Neuroradiology 09/2008; 14 Suppl 1:17-22. · 0.73 Impact Factor
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ABSTRACT: Vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is thought to cause ischemia. To evaluate the contribution of vasospasm to delayed cerebral ischemia (DCI), we investigated the effect of vasospasm on cerebral perfusion and the relationship of vasospasm with DCI. We studied 37 consecutive SAH patients with CT angiography (CTA) and CT perfusion (CTP) on admission and within 14 days after admission or at time of clinical deterioration. CTP values (cerebral blood volume, cerebral blood flow (CBF) and mean transit time), degree of vasospasm on CTA, and occurrence of DCI were recorded. Vasospasm was categorized as follows: no spasm (0-25% decrease in vessel diameter), moderate spasm (25-50% decrease), and severe spasm (>50% decrease). The correspondence of the flow territory of the most spastic vessel with the least perfused region was evaluated, and differences in perfusion values and occurrence of DCI between degrees of vasospasm were calculated with 95% confidence intervals (95% CI). Fourteen patients had no vasospasm, 16 were moderate, and seven were severe. In 65% of patients with spasm, the flow territory of the most spastic vessel corresponded with the least perfused region. There was significant CBF (milliliters per 100 g per minute) difference (-21.3; 95% CI, -37 <--> -5.3) between flow territories of severe and no vasospasm. Four of seven patients with severe, six of 16 with moderate, and three of 14 patients with no vasospasm had DCI. Vasospasm decreases cerebral perfusion, but corresponds with the least perfused region in only two thirds of our patients. Furthermore, almost half of patients with severe vasospasm do not have DCI. Thus, although severe vasospasm can decrease perfusion, it may not result in DCI.Neuroradiology 08/2009; 51(12):813-9. DOI:10.1007/s00234-009-0575-y · 2.37 Impact Factor
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ABSTRACT: Delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage worsens the prognosis and is difficult to diagnose. We investigated the diagnostic value of noncontrast CT (NCT), CT perfusion (CTP), and CT angiography (CTA) for DCI after clinical deterioration in patients with subarachnoid hemorrhage. We prospectively enrolled 42 patients with subarachnoid hemorrhage with clinical deterioration suspect for DCI (new focal deficit or Glasgow Coma Scale decrease >or=2 points) within 21 days after hemorrhage. All patients underwent NCT, CTP, and CTA scans on admission and directly after clinical deterioration. The gold standard was the clinical diagnosis DCI made retrospectively by 2 neurologists who interpreted all clinical data, except CTP and CTA, to rule out other causes for the deterioration. Radiologists interpreted NCT and CTP images for signs of ischemia (NCT) or hypoperfusion (CTP) not localized in the neurosurgical trajectory or around intracerebral hematomas, and CTA images for presence of vasospasm. Diagnostic values for DCI of NCT, CTP, and CTA were assessed by calculating sensitivities, specificities, positive predictive values, and negative predictive values with 95% CIs. In 3 patients with clinical deterioration, imaging failed due to motion artifacts. Of the remaining 39 patients, 25 had DCI and 14 did not. NCT had a sensitivity of 0.56 (95% CI, 0.37 to 0.73), specificity=0.71 (0.57 to 0.77), positive predictive value=0.78 (0.55 to 0.91), negative predictive value=0.48 (0.28 to 0.68); CTP: sensitivity=0.84 (0.65 to 0.94), specificity=0.79 (0.52 to 0.92), positive predictive value=0.88 (0.69 to 0.96), negative predictive value=0.73 (0.48 to 0.89); CTA: sensitivity=0.64 (0.45 to 0.80), specificity=0.50 (0.27 to 0.73), positive predictive value=0.70 (0.49 to 0.84), negative predictive value=0.44 (0.23 to 0.67). As a diagnostic tool for DCI, qualitative assessment of CTP is overall superior to NCT and CTA and could be useful for fast decision-making and guiding treatment.Stroke 09/2009; 40(11):3493-8. DOI:10.1161/STROKEAHA.109.559013 · 6.02 Impact Factor