Transmural Perfusion Ratio Research Articles

Stress myocardial perfusion computed tomography at 320 detector-row to detect hemodynamically significant coronary stenoses in the presence of a high coronary calcium score

Objectives: We sought to assess the diagnostic performance of visual and quantitative analysis of stress perfusion CT (CTP) imaging with 320-slice CT, when added to coronary computed tomographic angiography (CCTA), against invasively determined fractional flow reserve (FFR) in the presence of a high coronary calcium score. Background: Cardiac CT examination integrating CCTA and stress CTP allows for comprehensive assessment of coronary arterial stenosis and myocardial ischemia. However, further clinical validation is required in high-risk populations. Methods: Thirty-three patients with high calcium score stratified by higher than 400 Agatston units underwent comprehensive CT examination starting stress CTP followed by rest CCTA and angiography. FFR was measured in all main coronary arteries with a luminal narrowing greater than 50%. FFR<0.80 was considered hemodynamically significant. Two observers visually assessed presence or absence of perfusion defect in each major coronary arterial territory. The transmural perfusion ratio (TPR) was calculated using 16-segment model. Results: A total of 48 coronary vessels had flow limiting stenoses. The sensitivity and specificity of CCTA and visual CTP analysis alone to detect flow limiting CAD was 91% and 62%, respectively, and 77%, 73%, respectively. With use of quantitative analysis of CTP employing TPR, 5 lesions were correctly reclassified as hemodynamically significant, resulting in sensitivity of 87% and specificity of 75%. Combined assessment was better predictor of flow limiting CAD, with a sensitivity of 81% and specificity of 92%, with an AUC of 0.87, compared with 0.77 for CCTA alone and 0.81 for CTP alone. ![Figure][1] Figure 1 Conclusions: Stress myocardial CTP over CCTA had moderate sensitivity and high specificity for predicting flow limiting CAD. [1]: pending:yes

Sex- and age-related differences of myocardial perfusion at rest assessed with multidetector computed tomography

BackgroundThe clinical presentation of ischemic heart disease in women differs from men, which could reflect sex-related differences of normal physiology. Cardiac CT angiography provides a noninvasive method to assess both regional and transmural myocardial perfusion in addition to coronary atherosclerosis. ObjectiveThe aim of this study was to evaluate potential sex-related differences of (1) left ventricular (LV) myocardial perfusion measured as LV myocardial attenuation density/LV blood pool attenuation density (MyoAD-ratio) at rest and (2) transmural perfusion ratio (TPR) as a measure of endocardial perfusion relative to epicardial perfusion. MethodsMyocardial perfusion at rest and coronary artery atherosclerosis were evaluated with multidetector CT in 206 asymptomatic women and 203 age-matched men from the Copenhagen General Population Study. ResultsLV myocardial perfusion at rest (LV MyoAD-ratio) was higher in women than in men (9% difference; P = 0.039). In a multivariable analysis, including age, sex, cardiovascular risk factors, Agatston score, and presence of coronary stenosis, global LV MyoAD-ratio remained significantly higher in women than in men (P = 0.045). No effect of cardiovascular risk factors on myocardial perfusion at rest was noted. Myocardial perfusion at rest was correlated to age in men (r = 0.15, P = 0.031) but not in women (r = −0.01, P = 0.83). TPR was slightly lower in women than in men (1.12 vs 1.14; P = 0.0019). ConclusionLV myocardial perfusion at rest is higher in women than men independent of coronary atherosclerosis in asymptomatic subjects with risk factors.

Time Efficiency and Diagnostic Accuracy of New Automated Myocardial Perfusion Analysis Software in 320-Row CT Cardiac Imaging

ObjectiveWe aimed to evaluate the time efficiency and diagnostic accuracy of automated myocardial computed tomography perfusion (CTP) image analysis software.Materials and Methods320-row CTP was performed in 30 patients, and analyses were conducted independently by three different blinded readers by the use of two recent software releases (version 4.6 and novel version 4.71GR001, Toshiba, Tokyo, Japan). Analysis times were compared, and automated epi- and endocardial contour detection was subjectively rated in five categories (excellent, good, fair, poor and very poor). As semi-quantitative perfusion parameters, myocardial attenuation and transmural perfusion ratio (TPR) were calculated for each myocardial segment and agreement was tested by using the intraclass correlation coefficient (ICC). Conventional coronary angiography served as reference standard.ResultsThe analysis time was significantly reduced with the novel automated software version as compared with the former release (Reader 1: 43:08 ± 11:39 min vs. 09:47 ± 04:51 min, Reader 2: 42:07 ± 06:44 min vs. 09:42 ± 02:50 min and Reader 3: 21:38 ± 3:44 min vs. 07:34 ± 02:12 min; p < 0.001 for all). Epi- and endocardial contour detection for the novel software was rated to be significantly better (p < 0.001) than with the former software. ICCs demonstrated strong agreement (≥ 0.75) for myocardial attenuation in 93% and for TPR in 82%. Diagnostic accuracy for the two software versions was not significantly different (p = 0.169) as compared with conventional coronary angiography.ConclusionThe novel automated CTP analysis software offers enhanced time efficiency with an improvement by a factor of about four, while maintaining diagnostic accuracy.

Combined CT Coronary Angiography and Stress Myocardial Perfusion Imaging for Hemodynamically Significant Stenoses in Patients With Suspected Coronary Artery Disease: A Comparison With Fractional Flow Reserve

We sought to determine the accuracy of combined coronary computed tomography angiography (CTA) and computed tomography stress myocardial perfusion imaging (CTP) in the detection of hemodynamically significant stenoses using fractional flow reserve (FFR) as a reference standard in patients with suspected coronary artery disease. CTP can be qualitatively assessed by visual interpretation or quantified by the transmural perfusion ratio determined as the ratio of subendocardial to subepicardial contrast attenuation. The incremental value of each technique in addition to coronary CTA to detect hemodynamically significant stenoses is not known. Forty symptomatic patients underwent FFR and 320-detector computed tomography assessment including coronary CTA and CTP. Myocardial perfusion was assessed using the transmural perfusion ratio and visual perfusion assessment. Computed tomography images were assessed by consensus of 2 observers. Transmural perfusion ratio <0.99 was used as the threshold for abnormal perfusion. FFR ≤0.8 indicated hemodynamically significant stenoses. Coronary CTA detected FFR-significant stenoses with 95% sensitivity and 78% specificity. The additional use of visual perfusion assessment and the transmural perfusion ratio both increased the specificity to 95%, with sensitivity of 87% and 71%, respectively. The area under the receiver-operating characteristic curve for coronary CTA + visual perfusion assessment was significantly higher than both coronary CTA (0.93 vs. 0.85, p = 0.0003) and coronary CTA + the transmural perfusion ratio (0.93 vs. 0.79, p = 0.0003). Per-vessel and per-patient accuracy for coronary CTA, coronary CTA + the transmural perfusion ratio, and coronary CTA + visual perfusion assessment was 83% and 83%, 87% and 92%, and 92% and 95%, respectively. In suspected coronary artery disease, combined coronary CTA + CTP identifies patients with hemodynamically significant stenoses with >90% accuracy compared with FFR. When interpreted with coronary CTA, visual perfusion assessment provided superior incremental value in the detection of FFR-significant stenoses compared with the quantitative transmural perfusion ratio assessment.

Dipyridamole stress and rest transmural myocardial perfusion ratio evaluation by 64 detector-row computed tomography

Myocardial stress CT perfusion (CTP) can detect myocardial ischemia. We evaluated the transmural perfusion ratio (TPR) of dipyridamole stress CTP to detect significant coronary stenosis (>70%) defined by quantitative invasive coronary angiography (ICA). Twenty-six patients (61.6 ± 8.0 years old; 14 males), without prior myocardial infarction, with positive single-photon emission computed tomography (SPECT; <2 months) and clinical indication for ICA, underwent a customized multidetector-row CT (MDCT) protocol with rest/stress myocardial perfusion evaluation and coronary CT angiography. TPR was defined as mean subendocardial divided by mean subepicardial attenuation and quantified on rest and stress MDCT images. Abnormal TPR was defined as 2 SDs below the mean rest TPR. All 26 patients completed the CT protocol with no adverse events. Rest TPR was measured in all patients with a mean of 1.06 ± 0.11, and abnormal TPR was considered <0.85. For 6 patients with normal coronary arteries by ICA, the mean TPR of territories with a previous positive perfusion defect in SPECT was 1.02 ± 0.18 (95% CI, 0.86-1.18; n = 6), and mean TPR of territories without perfusion defect in SPECT was 1.03 ± 0.09 (95% CI, -0.95 to 1.11; n = 12; P = 0.83). Mean stress TPR in territories with positive SPECT and significant coronary artery disease by quantitative ICA was 0.71 ± 0.13 (95% CI, -0.64 to 0.77) and in the remote myocardial was 1.01 ± 0.09 (95% CI, -0.96 to 1.06; P < 0001). In these territories, a significant Pearson's correlation was observed (r = -0.74, P < 0.001). TPR has a good correlation with SPECT and ICA to detect significant coronary stenosis.

Adenosine Stress 64- and 256-Row Detector Computed Tomography Angiography and Perfusion Imaging

Background— Multidetector computed tomography coronary angiography (CTA) is a robust method for the noninvasive diagnosis of coronary artery disease. However, in its current form, CTA is limited in its prediction of myocardial ischemia. The purpose of this study was to test whether adenosine stress computed tomography myocardial perfusion imaging (CTP), when added to CTA, can predict perfusion abnormalities caused by obstructive atherosclerosis. Methods and Results— Forty patients with a history of abnormal single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) underwent adenosine stress 64-row (n=24) or 256-row (n=16) detector CTP and CTA. A subset of 27 patients had invasive angiography available for quantitative coronary angiography. CTA and quantitative coronary angiography were evaluated for stenoses ≥50%, and SPECT-MPI was evaluated for fixed and reversible perfusion deficits using a 17-segment model. CTP images were analyzed for the transmural differences in perfusion using the transmural perfusion ratio (subendocardial attenuation density/subepicardial attenuation density). The sensitivity, specificity, positive predictive value, and negative predictive value for the combination of CTA and CTP to detect obstructive atherosclerosis causing perfusion abnormalities using the combination of quantitative coronary angiography and SPECT as the gold standard was 86%, 92%, 92%, and 85% in the per-patient analysis and 79%, 91%, 75%, and 92% in the per vessel/territory analysis, respectively. Conclusions— The combination of CTA and CTP can detect atherosclerosis causing perfusion abnormalities when compared with the combination of quantitative coronary angiography and SPECT.

Abstract 4718: Combined Adenosine Stress Perfusion and Coronary Angiography Using 320-Row Detector Dynamic Volume Computed Tomography in Patients with Suspected Coronary Artery Disease

Dynamic volume 320-row detector computed tomography (CT), with full cardiac coverage, allows for the combination of non-invasive angiography (CTA) performed at rest with myocardial perfusion imaging (MPI) during adenosine stress. The purpose of this study was to test the accuracy of combined CTA and MPI using dynamic volume 320-row detector CT to identify atherosclerosis causing territorial ischemia. Eighteen patients with chest pain and intermediate to high pre-test likelihood of coronary artery disease (CAD) underwent rest CTA and stress CT-MPI following radionuclide MPI using the following prospective ECG-gated protocol: Rest CTA: 320 × 0.5mm, 120 kV, 400 mA, 70 – 80% R-R interval followed by Stress CT-MPI: adenosine (140μg/kg/min), 320 × 0.5mm, 120 kV, 400 mA, 70 – 80% R-R interval. CT-MPI images were reconstructed in the short axis with a 3 mm slice thickness. The transmural perfusion ratio (TPR) was calculated by dividing the endocardial attenuation density (AD) by the epicardial AD in each sector. Ischemia was defined as a TPR &lt;0.99 on adenosine stress CT-MPI that normalized on the rest CTA images. CTA was analyzed for stenoses ≥50% and radionuclide MPI was analyzed for fixed and reversible perfusion abnormalities. Using a 17-segment model in a territory/vessel based analysis, the combination of CTA + CT-MPI was compared with CTA 3 radionuclide MPI (gold standard) for its ability to detect atherosclerosis causing territorial ischemia. Mean TPRs in ischemic and normal territories were 0.90±0.09 and 1.13±0.10, respectively (p&lt;0.001). The sensitivity, specificity, positive (PPV) and negative predictive value (NPV) for CTA + CT-MPI were 86%, 85%, 67, and 94% compared with the gold standard; respectively. However, when adjusting for balanced multivessel disease the sensitivity, specificity, PPV, and NPV were 89%, 94%, 89%, and 94%; respectively. Mean effective radiation dose for the combined rest (4.9±0 mSv) and stress (8.5±0.5mSv) protocols was 13.4±0.5 mSv. The combination of CTA and CT -MPI, using 320-row detector dynamic volume CT, is capable of accurately identifying myocardial ischemia in the presence of obstructive atherosclerosis and compares well with CTA/radionuclide MPI.

Abstract 2547: Quantification of Myocardial Perfusion in Patients Using 256-Row Multidetector Computed Tomography: Evaluation of Endocardial vs. Epicardial Blood Flow

Introduction: The advent of 256x0.5 mm high resolution multidetector computed tomography (MDCT) created the potential to quantify subendocardial myocardial blood flow (MBF) reduction, the hallmark of ischemia. The purpose of this study was to test the hypothesis that adenosine stress / rest 256x0.5mm MDCT can detect ischemia by measuring differences in subendo-cardial versus subepicardial MBF. Methods: Nineteen patients with abnormal SPECT perfusion studies underwent adenosine (140μg/kg/min) stress 256x0.5mm MDCT perfusion imaging (CTP): 120kV, 100mAs, 3 gantry rotations at 0.5 secs, followed by rest 256x0.5mm MDCT angiography (CTA): 120kV, 175mAs, 3 gantry rotations at 0.5 secs. CT perfusion images were reconstructed in the short axis with a 3 mm slice thickness. Endocardial and epicardial borders were defined, myocardium was sectored according to the standard 17 segment model, and divided circumferentially into endocardial and epicardial layers. The transmural perfusion ratio (TPR) was calculated by dividing the endocardial attenuation density (AD) by the epicardial AD in each sector. Ischemia was defined as TPR &lt;0.8 in more than one sector. The TPR results were compared to the presence or absence of stenoses ≥50% on CTA and perfusion deficits on SPECT. Results: Mean TPR in abnormal and normal sectors was 0.71±0.05 and 1.01±0.06, respectively (p&lt;0.01). Mean number of abnormal sectors for patients with no stenoses, 1-vessel, and multi-vessel disease were 1.6, 2.5, and 6.3; respectively (p&lt;0.05). The sensitivity and specificity of TPR for detecting a stenosis ≥50% severity was 62% and 86% compared with 62% and 71% for SPECT (NS). When defining territorial ischemia as a SPECT perfusion abnormality plus a stenosis ≥50%, the sensitivity, specificity, positive and negative predictive values were 75%, 95%, 75%, and 95% for combined CTA/CTP imaging, respectively. Conclusions: The transmural perfusion ratio measured from 256x0.5mm MDCT perfusion images can detect the presence of obstructive atherosclerosis with similar accuracy compared with SPECT imaging. The combination of 256x0.5mm MDCT angiography and perfusion imaging may avoid the high false positive rate seen with SPECT imaging alone as well as improve its prediction of territorial ischemia.