Myocardial Blood Flow Values Research Articles

5962Incremental prognostic value of hybrid PET-CT assessed myocardial blood flow, coronary stenosis severity and adverse plaque characteristics

Abstract Background Management of patients with suspected coronary artery disease (CAD) can be optimized with prognostic information derived from non-invasive imaging such as positron emission tomography (PET) perfusion imaging and coronary computed tomography angiography (CCTA). The aim of the present study was to determine the incremental prognostic value of combined functional testing using PET perfusion imaging and anatomical testing using CCTA-derived stenosis severity and morphological assessment of CCTA-derived plaque morphology. Methods In this retrospective study, 539 patients referred for hybrid [15O]H2O PET – CCTA imaging because of suspected CAD were investigated. PET perfusion imaging was used to determine hyperemic myocardial blood flow (MBF), whereas CCTA images were evaluated for obstructive stenosis and high-risk plaque morphology. Major adverse coronary events (MACE) included all-cause death, non-fatal myocardial infarction (MI), urgent revascularization and late non-urgent revascularization (i.e. not guided by initial diagnostic work-up with non-invasive imaging). Kaplan Meier analysis and Cox proportional hazard regression were used to evaluate the independent prognostic value of PET-derived MBF, CCTA-derived stenosis and CCTA-derived high-risk plaque. Results During a mean follow-up of 6.8 [4.8–7.9] years, 79 (14.7%) patients experienced MACE, including 23 (4.3%) deaths, 19 (3.5%) MIs, 8 (1.5%) urgent revascularizations and 29 (5.4%) late non-urgent revascularizations. Annualized event rates for normal vs. abnormal results of PET perfusion imaging, CCTA-derived stenosis and high-risk plaque morphology were 1.2% vs 4.1%, 0.6% vs 4.4%, and 1.7% vs 5.6%, respectively (p<0.001 for all). The combined use of these three imaging parameters resulted in excellent long-term risk prediction, with a MACE-free survival of 97% in patients with no positive imaging findings. In contrast, MACE-free survival was only 69% in patients in whom all imaging findings were positive (figure 1). Multivariate Cox proportional hazard regression demonstrated incremental prognostic value of PET perfusion imaging, CCTA-derived stenosis and CCTA-derived high-risk plaques for the occurrence of MACE (p<0.05 for all) MACE-free survival stratified by PET-CT Conclusion PET-derived myocardial blood flow and CCTA-derived stenosis severity and high-risk plaque morphology are independent long-term predictors of adverse cardiac events and provide incremental prognostic value. Combined functional, anatomical and morphological assessment may allow for improved risk stratification in patients with suspected CAD.

Comparative Prognostic and Diagnostic Value of Myocardial Blood Flow and Myocardial Flow Reserve After Cardiac Transplantation

Cardiac allograft vasculopathy (CAV) is a major cause of graft failure after cardiac transplantation. CAV is characterized by diffuse involvement of epicardial coronary arteries and the microvasculature. PET allows quantification of absolute myocardial blood flow (MBF) and myocardial flow reserve (MFR), which may be accurate markers of CAV severity. We compared the diagnostic and prognostic utility of stress MBF and MFR after cardiac transplantation. Methods: This was a cohort study of consecutive cardiac transplant patients undergoing 82Rb PET scans. Semiquantitative regional analysis and global measurement of stress MBF and MFR were performed. Associations with all-cause mortality were assessed with multivariable Cox analysis. The diagnostic accuracy for significant CAV (grade 2/3) and the prognostic accuracy of stress MBF and MFR, corrected and uncorrected for rate-pressure product, were compared. Results: In total, 99 patients, mean age 68.8 y and 75.8% male, were followed for a median of 3.4 y, during which 26 deaths occurred. Stress MBF and MFR had similar diagnostic accuracy for significant CAV. However, uncorrected MFR had improved discrimination for all-cause mortality compared with stress MBF (area under the curve, 0.748 vs. 0.639; P = 0.048). Higher MFR (adjusted hazard ratio, 0.30; P < 0.001), but not stress MBF (adjusted hazard ratio, 1.14; P = 0. 656), was associated with reduced all-cause mortality. Preserved MFR (>2.0) identified relatively low-risk patients (annual mortality, 4.7%), whereas the presence of a left ventricular ejection fraction lower than 45% and MFR lower than 1.7 identified high-risk patients (annual mortality, 51.6%). Conclusion: Quantitative PET analysis, and particularly MFR, has diagnostic and prognostic utility after heart transplantation. Preserved MFR identifies low-risk patients, whereas the presence of multiple abnormal parameters identifies high-risk patients.

Quantification of porcine myocardial perfusion with modified dual bolus MRI \u2013 a prospective study with a PET reference

BackgroundThe reliable quantification of myocardial blood flow (MBF) with MRI, necessitates the correction of errors in arterial input function (AIF) caused by the T1 saturation effect. The aim of this study was to compare MBF determined by a traditional dual bolus method against a modified dual bolus approach and to evaluate both methods against PET in a porcine model of myocardial ischemia.MethodsLocal myocardial ischemia was induced in five pigs, which were subsequently examined with contrast enhanced MRI (gadoteric acid) and PET (O-15 water). In the determination of MBF, the initial high concentration AIF was corrected using the ratio of low and high contrast AIF areas, normalized according to the corresponding heart rates. MBF was determined from the MRI, during stress and at rest, using the dual bolus and the modified dual bolus methods in 24 segments of the myocardium (total of 240 segments, five pigs in stress and rest). Due to image artifacts and technical problems 53% of the segments had to be rejected from further analyses. These two estimates were later compared against respective rest and stress PET-based MBF measurements.ResultsValues of MBF were determined for 112/240 regions. Correlations for MBF between the modified dual bolus method and PET was rs = 0.84, and between the traditional dual bolus method and PET rs = 0.79. The intraclass correlation was very good (ICC = 0.85) between the modified dual bolus method and PET, but poor between the traditional dual bolus method and PET (ICC = 0.07).ConclusionsThe modified dual bolus method showed a better agreement with PET than the traditional dual bolus method. The modified dual bolus method was found to be more reliable than the traditional dual bolus method, especially when there was variation in the heart rate. However, the difference between the MBF values estimated with either of the two MRI-based dual-bolus methods and those estimated with the gold-standard PET method were statistically significant.

Myocardial CT perfusion imaging and atherosclerotic plaque characteristics on coronary CT angiography for the identification of myocardial ischaemia

To investigate the value of myocardial computed tomography (CT) perfusion imaging (CTP) and atherosclerotic plaque characteristics (APCs) identified on coronary CT angiography (CCTA) for the detection of myocardial ischaemia by using single-photon-emission CT (SPECT) as a reference. Thirty-six patients (63.9% males) undergoing combined stress dynamic CTP and CCTA were enrolled and analysed. Myocardial blood flow (MBF) from CTP was quantified and compared between normal and abnormal segments. The ability of CTP and APCs to detect ischaemia was compared to that of SPECT. Nineteen patients with 78 segments had perfusion abnormalities on CTP. A significant difference was seen in MBF values between normal (118.51±27.86 ml/100 ml/min) and hypoperfused (79.60±21.35 ml/100 ml/min) segments (t=15.832, p<0.05). The sensitivity and specificity for identifying ischaemia were 90.91% and 94.97%, respectively, on a per-segment basis, resulting in a r value of 0.737 (p<0.05). On a per-vessel basis, the sensitivity and specificity for detecting ischaemia were 86.67% and 84.62%, respectively, for CTP; 93.33% and 58.97%, respectively, for CCTA; and 86.67% and 87.18%, respectively, for CTP combined with CTA, with an area under the receiver-operator characteristic curve (AUC) being 0.87 (p<0.05) and 0.887 (p<0.05) for CTP and its combination with CTA, respectively. On CCTA, 55 vessels with APCs were detected, with an AUC of 0.737 (p<0.05) for APCs combined with CCTA stenosis and 0.802 (p<0.05) for APCs combined with CTP. Dynamic stress CTP shows good correlation with SPECT for the detection of ischaemia. Additionally, combining APCs with CCTA stenosis has the ability to discriminate ischaemic stenosis.

P387The value of myocardial blood flow and coronary flow reserve assessment in patients with multivessel coronary artery disease

P387The value of myocardial blood flow and coronary flow reserve assessment in patients with multivessel coronary artery disease

P309Prognostic value of global stress myocardial blood flow in patients with suspected obstructive coronary artery disease

P309Prognostic value of global stress myocardial blood flow in patients with suspected obstructive coronary artery disease

Splenic Blood Flow Increases after Hypothermic Stimulus (Cold Pressor Test): A Perfusion Magnetic Resonance Study.

The Cold Pressor Test (CPT) is a novel diagnostic strategy to noninvasively assess the myocardial microvascular endothelial-dependent function using perfusion magnetic resonance imaging (MRI). Spleen perfusion is modulated by a complex combination of several mechanisms involving the autonomic nervous system and vasoactive mediators release. In this context, the effects of cold temperature on splenic blood flow (SBF) still need to be clarified. Ten healthy subjects were studied by MRI. MRI protocol included the acquisition of GRE T1-weighted sequence (“first pass perfusion”) during gadolinium administration (0.1mmol/kg of Gd-DOTA at flow of 3.0 ml/s), at rest and after CPT. Myocardial blood flow (MBF) and SBF were measured by applying Fermi function deconvolution, using the blood pool input function sampled from the left ventricle cavity. MBF and SBF values after performing CPT were significantly higher than rest values (SBF at rest: 0.65 ± 0.15 ml/min/g Vs. SBF after CPT: 0.90 ± 0.14 ml/min/g, p: <0.001; MBF at rest: 0.90 ± 0.068 ml/min/g Vs. MBF after CPT: 1.22 ± 0.098 ml/min/g, p<0.005). Both SBF and MBF increased in all patients during the CPT. In particular, the CPT-induced increase was 43% ± 29% for SBF and 36.5% ± 17% for MBF. CPT increases SBF in normal subjects. The characterization of a standard perfusion response to cold might allow the use of the spleen as reference marker for the adequacy of cold stimulation during myocardial perfusion MRI.

Application of the One-Stop Cardiac CT Scan on 256-Row Wide Detector Revolution CT in Myocardial Ischemia of Aortic Valve Degeneration Diagnosis

Background: Advances in Imaging has been used increasingly to assess coronary lumen and myocardial perfusion with more accuracy. Objectives: The aim of this study was to evaluate the diagnostic performance of one-stop cardiac CT myocardial perfusion imaging (CT-MPI) combined with coronary artery CT angiography (CCTA) for the detection of functionally relevant myocardial ischemia of aortic valve degeneration (AVD). The study was approved by the patient and passed by the ethics committee. Methods: This study was a case-control study using random sampling. A total of 109 (109/480) patients suspected of CAD were prospectively enrolled from January 2017 to December 2018 with chest pain as their chief complaint in Renmin Hospital of Wuhan University, Wuhan, Hubei, China. All patients underwent CT-MPI and CCTA on a wide detector Revolution CT. Myocardial blood flow (MBF) was quantified and compared between normal perfusion and abnormal myocardial segments based on AHA-17-segment model. CCTA images were evaluated qualitatively based on SCCT-18-segment model. Radionuclide myocardial perfusion imaging (MPI) is the gold standard; the diagnostic accuracy of CT-MPI, CCTA, and CT-MPI combination with CCTA in the diagnosis of myocardial ischemia of AVD with hemodynamic stenosis was evaluated. Results: All patients underwent CCTA combined with CT-MPI examination, 69 patients (63.30%) with 182 myocardial segments(15. 52%) were detected with decreased blood perfusion, the MBF value was lower than that of normal segments [(83.06 ± 20.11) mL.100 mL-1.min-1 vs. (120.02 ± 28.71) mL.100 mL-1.min-1; t = 14.361, P < 0.001]. There were 1914 segments (97.56%) that could be used for the diagnosis in CCTA, 302 (15.78%) segments have clinical significance in this study. Compared with the MPI, the diagnostic sensitivity, specificity, positive and negative predictive value of CT-MPI for myocardial ischemia of AVD were 73.33%, 73.68%, 89.80%, 70.00%, respectively, 90.00%, 68.42%, 88.24%, 72.22% for CCTA, and 88.46%, 70.59%, 90.20%, 66.67% combined with CT-MPI and CCTA. Logistic regression analysis was performed that the AVD was associated with the detection rate of calcified plaques (r = 5.207, P < 0.05), and calcification of the aortic valve were associated with the detection of plaques in the three and six segments of coronary arteries (P < 0.05). Conclusions: Both good CCTA and CT-MPI images can be obtained at the one-stop scanning by Revolution CT. This can be used for the diagnosis of AVD combined with myocardial ischemia. Revolution CT can accurately measure myocardial hemodynamic changes, and provide imaging evidence for the diagnosis and treatment of aortic valve degeneration.

Optimal repetition time for free breathing myocardial arterial spin labeling.

The aim of this study was to improve the scan efficiency of ASL in the myocardium. Free breathing FAIR-ASL scans with different TRs were compared, while keeping the acquisition time constant. Scans were named by the trigger pulse that started each acquisition: every two (TP1), four (TP2) and six (TP3) cardiac cycles. TP2 offered the best alternative with a coefficient of variation of 17.15% intrasession and 36.85% intersession. Mean MBF increased by 0.22±0.41ml/g/min with mild stress.

Impact of regadenoson-induced myocardial creep on dynamic Rubidium-82 PET myocardial blood flow quantification

BackgroundRepositioning of the heart during myocardial perfusion imaging (MPI) using Rubidium-82 (Rb-82) PET may occur when using regadenoson. Our aim was to determine the prevalence and the effect of correcting for this myocardial creep on myocardial blood flow (MBF) quantification. MethodsWe retrospectively included 119 consecutive patients who underwent dynamic rest- and regadenoson-induced stress MPI using Rb-82 PET. The presence of myocardial creep was visually assessed in the dynamic stress PET series by identifying differences between the automatically drawn myocardium contour and the activity. Uncorrected and corrected stress MBFs were compared for the three vascular territories (LAD, LCX, and RCA) and for the whole myocardium. ResultsMyocardial creep was observed in 52% of the patients during stress. Mean MBF values decreased after correction in the RCA from 4.0 to 2.7 mL/min/g (P < 0.001), in the whole myocardium from 2.7 to 2.6 mL/min/g (P = 0.01), and increased in the LAD from 2.5 to 2.6 mL/min/g (P = 0.03) and remained comparable in the LCX (P = 0.3). ConclusionsMyocardial creep is a frequent phenomenon when performing regadenoson-induced stress Rb-82 PET and has a significant impact on MBF values, especially in the RCA territory. As this may hamper diagnostic accuracy, myocardial creep correction seems necessary for reliable quantification.

Myocardial Perfusion Imaging for the Evaluation of Ischemic Heart Disease in Women

To review the value of myocardial blood flow and coronary flow reserve (CFR) measurements, as assessed by positron emission tomography (PET), in women with suspected ischemic heart disease. CFR is a noninvasive measure of coronary vasomotor function that integrates the hemodynamic effects of epicardial coronary stenosis, diffuse atherosclerosis, and microvascular dysfunction on myocardial tissue perfusion and has emerged as an imaging marker of cardiovascular risk, independently of the degree of obstructive coronary artery disease (CAD). Normal coronary arteries or nonobstructive CAD is a common finding in women with ischemia. Thus, assessment of risk based on a coronary stenosis approach may fail in women. PET is able to quantify absolute myocardial blood flow and CFR which may help to elucidate other mechanisms involved such as microvascular dysfunction and diffuse epicardial CAD, responsible for the disease in women.

Prevalence of Decreased Myocardial Blood Flow in Symptomatic Patients with Patent Coronary Stents: Insights from Low-Dose Dynamic CT Myocardial Perfusion Imaging.

To study the prevalence and clinical characteristics of decreased myocardial blood flow (MBF) quantified by dynamic computed tomography (CT) myocardial perfusion imaging (MPI) in symptomatic patients without in-stent restenosis. Thirty-seven (mean age, 71.3 ± 10 years; age range, 48-88 years; 31 males, 6 females) consecutive symptomatic patients with patent coronary stents and without obstructive de novo lesions were prospectively enrolled to undergo dynamic CT-MPI using a third-generation dual-source CT scanner. The shuttle-mode acquisition technique was used to image the complete left ventricle. A bolus of contrast media (50 mL; iopromide, 370 mg iodine/mL) was injected into the antecubital vein at a rate of 6 mL/s, followed by a 40-mL saline flush. The mean MBF value and other quantitative parameters were measured for each segment of both stented-vessel territories and reference territories. The MBFratio was defined as the ratio of the mean MBF value of the whole stent-vessel territory to that of the whole reference territory. An MBFratio of 0.85 was used as the cut-off value to distinguish hypoperfused from non-hypoperfused segments. A total of 629 segments of 37 patients were ultimately included for analysis. The mean effective dose of dynamic CT-MPI was 3.1 ± 1.2 mSv (range, 1.7-6.3 mSv). The mean MBF of stent-vessel territories was decreased in 19 lesions and 81 segments. Compared to stent-vessel territories without hypoperfusion, the mean MBF and myocardial blood volume were markedly lower in hypoperfused stent-vessel territories (77.5 ± 16.6 mL/100 mL/min vs. 140.4 ± 24.1 mL/100 mL/min [p < 0.001] and 6.4 ± 3.7 mL/100 mL vs. 11.5 ± 4 mL/100 mL [p < 0.001, respectively]). Myocardial hypoperfusion in stent-vessel territories was present in 48.6% (18/37) of patients. None of clinical parameters differed statistically significantly between hypoperfusion and non-hypoperfusion subgroups. Decreased MBF is commonly present in patients who are symptomatic after percutaneous coronary intervention, despite patent stents and can be detected by dynamic CT-MPI using a low radiation dose.

Impact of individualized segmentation on diagnostic performance of quantitative positron emission tomography for haemodynamically significant coronary artery disease.

Despite high variability in coronary anatomy, quantitative positron emission tomography (PET) perfusion in coronary territories is traditionally calculated according to the American Heart Association (AHA) 17-segments model. This study aimed to assess the impact of individualized segmentation of myocardial segments on the diagnostic accuracy of hyperaemic myocardial blood flow (MBF) values for haemodynamically significant coronary artery disease (CAD). Patients with suspected CAD (n = 204) underwent coronary computed tomography angiography (CCTA) and [15O]H2O PET followed by invasive coronary angiography with fractional flow reserve assessment of all major coronary arteries. Hyperaemic MBF per vascular territory was calculated using both standard segmentation according to the AHA model and individualized segmentation, in which CCTA was used to assign coronary arteries to PET perfusion territories. In 122 (59.8%) patients, one or more segments were redistributed after individualized segmentation. No differences in mean MBF values were seen between segmentation methods, except for a minor difference in hyperaemic MBF in the LCX territory (P = 0.001). These minor changes resulted in discordant PET-defined haemodynamically significant CAD between the two methods in only 5 (0.8%) vessels. The diagnostic value for detecting haemodynamically significant CAD did not differ between individualized and standard segmentation, with area under the curves of 0.79 and 0.78, respectively (P = 0.34). Individualized segmentation using CCTA-derived coronary anatomy led to redistribution of standard myocardial segments in 60% of patients. However, this had little impact on [15O]H2O PET MBF values and diagnostic value for detecting haemodynamically significant CAD did not change. Therefore, clinical impact of individualized segmentation seems limited.

19. Comparison of myocardial blood flow estimates from dynamic contrast-enhanced used in Cardiac Magnetic Resonance Imaging

Purpose Dynamic Contrast-Enhanced Cardiovascuar Magnetic Resonance Imaging (DCE-CMRI) may quantitatively assess the Myocardial Blood Flow (MBF), recovering the tissue impulse-response function to transit of gadolinium bolus through myocardium. Several deconvolution techniques are available, using various models for the impulse-response [1] . The method choice may influence the results, producing differences that have not been deeply investigated yet. Methods Three methods for quantifying myocardial perfusion were compared: Fermi Function Modeling, Tofts Model, and Gamma Function model, the latter traditionally used in brain perfusion. Thirty human subjects were studied at rest, and Cold Pressor Test stress, injecting a single-bolus of gadolinium of 0.1 mmol/kg. Perfusion estimate differences among methods were analysed by paired comparisons with Student’s t-test, linear regression analysis, and Bland-Altman plots, and using also the two-way ANOVA, considering the MBF values of all patients grouped according to two categories: calculation method and rest/stress conditions. Results Perfusion estimates obtained by various methods in both rest and stress conditions were not significantly different, and in agreement with the literature. Results obtained during the first-pass transit time (20 s) yielded p-values in the range 0.20–0.28 for the Student’s t-test, slopes from the linear regression analysis between 0.98–1.03, and R values between 0.92–1.01. With the two-way ANOVA, the results were p = 0.20 for the method effect (not significant), p Conclusion MBF estimates obtained by various methods at rest/stress condition were not significantly different in the first-pass transit time, encouraging quantitative perfusion estimates in DCE-CMRI with the used methods.

Intermodel disagreement of myocardial blood flow estimation from dynamic CT perfusion imaging

PurposeTo assess the intermodel agreement of different tracer kinetic models to determine myocardial blood flow (MBF) and their diagnostic accuracy in coronary artery disease (CAD) at dynamic CT myocardial perfusion imaging (CTMPI). MethodsThree porcine hearts perfused in Langendorff mode and 15 patients with suspected CAD and perfusion single photon emission CT (SPECT) were included. Dynamic CTMPI was performed in shuttle-mode (70 kVp, 350mAs/rot) on 3rd generation dual-source CT. In porcine hearts and patients, myocardial segments (AHA-16-segment model) were drawn. Tissue attenuation curves were constructed per segment and arterial input functions were derived from the aorta. True MBF was calculated with input flow and weight of the porcine hearts. In patients, ischemic segments were based on SPECT results. MBF quantification was performed using the VPCT-software, Upslope, Extended Toft (ET), Two-compartment (TC) and Fermi models. ResultsIn porcine hearts, true MBF was 1.88 (interquartile range [IQR]:1.80-2.80)mL/g/min. Diagnostic accuracy was similar for all models: 0.96, 0.99, 0.92, 0.93 and 0.96 for VPCT software, Upslope method, Fermi, ET and TC model. The VPCT software and Upslope method resulted in lower MBF (median 1.44 [1.29–1.58] and 1.39 [1.25–1.59]mL/g/min) compared to the Fermi, ET, and TC model (median values of 1.76 mL/g/min [1.36–2.44], 2.55 mL/g/min [2.20–2.92], and 1.98 mL/g/min [1.60–2.60], respectively [p < 0.001]). In patients, all models showed a significant difference in MBF between the 34 ischemic and 206 non-ischemic segments (p-value<0.001). ConclusionAbsolute MBF values are significantly different between the models and a uniform threshold could not be determined; however, diagnostic accuracy for detecting ischemia is similar.

Accelerated, first-pass cardiac perfusion pulse sequence with radial k-space sampling, compressed sensing, and k-space weighted image contrast reconstruction tailored for visual analysis and quantification of myocardial blood flow.

To develop an accelerated cardiac perfusion pulse sequence and test whether it is capable of increasing spatial coverage, generating high-quality images, and enabling quantification of myocardial blood flow (MBF). We implemented an accelerated first-pass cardiac perfusion pulse sequence by combining radial k-space sampling, compressed sensing (CS), and k-space weighted image contrast (KWIC) filtering. The proposed and clinical standard pulse sequences were evaluated in a randomized order in 13 patients at rest. For visual analysis, 3 readers graded the conspicuity of wall enhancement, artifact, and noise level on a 5-point Likert scale (overall score index = sum of 3 individual scores). Resting MBF was calculated using a Fermi function model with and without KWIC filtering. Mean visual scores and MBF values were compared between sequences using appropriate statistical tests. The proposed pulse sequence produced greater spatial coverage (6-8 slices) with higher spatial resolution (1.6 × 1.6 × 8 mm3 ) and shorter readout duration (78 ms) compared to clinical standard (3-4 slices, 3 × 3 × 8 mm3 , 128 ms, respectively). The overall image score index between accelerated (11.1 ± 1.3) and clinical standard (11.2 ± 1.3) was not significantly different (P = 0.64). Mean resting MBF values with KWIC filtering (0.9-1.2 mL/g/min across different slices) were significantly lower (P < 0.0001) than those without KWIC filtering (3.1-4.3 mL/g/min) and agreed better with values reported in literature. An accelerated, first-pass cardiac perfusion pulse sequence with radial k-space sampling, CS, and KWIC filtering is capable of increasing spatial coverage, generating high-quality images, and enabling quantification of MBF.

Abstract 16649: Recovery of Myocardial Perfusion After Percutaneous Coronary Intervention of Chronic Total Occlusions is Comparable to Non-Occlusive Lesions

Background: The benefits of chronic coronary total occlusion (CTO) percutaneous coronary intervention (PCI) are being questioned. The aim of this study was to assess the effects of CTO PCI on absolute myocardial perfusion, as compared to PCI of hemodynamically significant non-occlusive lesions. Methods: Consecutive patients with a preserved left ventricular ejection fraction (≥50%) and a CTO or non-CTO lesion, in whom [ 15 O]H 2 O positron emission tomography was performed prior and after successful PCI, were included. Change in quantitative (hyperemic) myocardial blood flow (MBF), coronary flow reserve (CFR) and perfusion defect size (in myocardial segments) were compared between CTOs and non-occlusive lesions. Results: Ninety-two patients with a CTO and 31 patients with a non-occlusive lesion were included. CTOs induced larger perfusion defect sizes (4.51±1.69 vs. 3.23±2.38 segments, p&lt;0.01) with lower hyperemic MBF (1.30±0.37 vs. 1.58±0.62 mL·min -1 ·g -1 , p&lt;0.01) and similarly impaired CFR (1.66±0.75 vs. 1.89±0.77, p=0.17) compared with non-occlusive lesions. After PCI both hyperemic MBF and CFR increased similarly between groups (p=0.57 and p=0.35) to normal ranges with higher hyperemic MBF values in non-CTO compared to CTO (2.89±0.94 vs. 2.48±0.73 mL·min -1 ·g -1 , p=0.03). Perfusion defect sizes decreased similarly after CTO PCI and non-CTO PCI (p=0.14), leading to small residual defect sizes in both groups (1.15±1.44 vs. 0.61±1.45 segments, p=0.054). Conclusions: Percutaneous revascularization of CTOs improves absolute myocardial perfusion similarly to PCI of hemodynamically significant non-occlusive lesions, leading to satisfying results. Myocardial perfusion findings are less favorable in patients with a CTO before and after PCI, suggesting a more advanced stage of coronary artery disease.

15O-H2O PET/CT as a tool for the quantitative assessment of early post-radiotherapy changes of heart perfusion in breast carcinoma patients.

Studies examining radiation-induced heart toxicity in breast cancer patients are inconclusive. The aim of this study was to prospectively and quantitatively asses myocardial blood flow (MBF) with, for the first time, 15O-H2O PET/CT as a marker of heart damage in irradiated breast cancer patients. 15 breast cancer patients receiving intact breast or chest wall irradiation were included in the analysis (six with right-sided and nine with left-sided breast cancer). They underwent 15O-H2O PET/CT before radiotherapy (RT) and 2 and 8 months after RT. MBF was quantitatively assessed at rest and under stress conditions in 17 heart segments distinguished according to the American Ultrasound Association classification. Regional MBF values were derived in each of the coronary artery territories. MBF decreased in 53% and increased in 33% of cases 2 months after RT in both left-sided and right-sided breast cancer patients. Stress testing was more sensitive than at-rest testing, demonstrating decreased perfusion in the segments supplied by the left anterior descending coronaryartery (LAD) [5.41 ± 1.74 vs 4.52 ± 1.82 ml (g*min)-1; p = 0.018], which persisted at 6 months [5.41 ± 1.74 vs 4.40 ± 1.38 ml(g*min)-1; p = 0.032] and a decrease in global heart perfusion [5.14 ± 1.49 vs 4.46 ± 1.73 ml(g*min)-1; p = 0.036]. A minimal radiation dose applied to the LAD correlated with MBF changes observed 2 months after RT (r = -0.57; p = 0.032). Radiological findings were not correlated with clinical symptoms of heart toxicity. 15O-H2O PET/CT is safe and effective for the early detection and quantitative analysis of subclinical post-RT changes in heart perfusion in breast cancer patients. The LV segments supplied by the LAD are the main site of MBF changes. A minimum radiation dose deposited in the LAD may be a predictor of radiation-induced heart toxicity. Advances in knowledge: This is the first time that 15O-H2O PET/CT has been used to assess MBF after RT and the first granular description of the distribution of blood flow changes after breast cancer RT.

Incremental Prognostic Value of Myocardial Blood Flow Quantified With Stress Dynamic Computed Tomography Perfusion Imaging

ObjectivesThis study aimed to evaluate whether myocardial blood flow (MBF) quantified with dynamic computed tomography perfusion imaging (CTP) has an incremental prognostic value over coronary CT angiography (CTA) for major adverse cardiac events (MACEs) in patients with suspected coronary artery disease (CAD). BackgroundThe incremental prognostic value of CTP over CTA is unclear. The quantification of MBF with dynamic CTP may potentially enhance risk stratification. MethodsA total of 332 patients (67% men; age: 67 ± 10 years) with suspected CAD who underwent CTA and dynamic CTP was analyzed. A MACE was defined as cardiac death, nonfatal myocardial infarction (MI), unstable angina, or hospitalization for congestive heart failure. A summed stress score (SSS) was calculated by adding scores of all myocardial segments according to normalized MBF values. Abnormal perfusion was defined as SSS ≥4. Obstructive CAD was defined as ≥50% stenosis in ≥1 vessel on CTA. ResultsDuring a median follow-up of 2.5 years, 19 patients had a MACE. Multivariate analysis showed that, when adjusted for obstructive CAD on CTA, abnormal perfusion was significantly associated with hazards for MACEs (hazard ratio [HR]: 5.7; 95% confidence interval [CI]: 1.9 to 16.9; p = 0.002), with a significant improvement in the prognostic value. Abnormal perfusion was an independent predictor even when adjusted for ≥70% stenosis in ≥1 vessel (HR: 5.4; 95% CI: 1.7 to 16.7; p = 0.003) or adjusted for ≥50% stenosis in ≥2 vessels (HR: 6.5; 95% CI: 2.2 to 18.9; p = 0.001). In the setting of obstructive CAD, annualized event rates showed a significant difference between the patients with and without abnormal perfusion for all events (12.2% vs. 1.5%; p = 0.002) and for cardiac death and nonfatal MI (4.2% vs. 0%; p = 0.015). ConclusionsMBF quantified with dynamic CTP has an incremental prognostic value over CTA. The addition of dynamic CTP to CTA allows improved risk stratification of patients with CTA-detected stenosis.

Diagnostic value of quantitative coronary flow reserve and myocardial blood flow estimated by dynamic 320 MDCT scanning in patients with obstructive coronary artery disease.

We have developed the method for dynamic 320-row multidetector computed tomography (MDCT)-derived quantitative coronary flow reserve (CFRCT) and hyperemic myocardial blood flow (MBFCT). We evaluated diagnostic value of CFRCT and hyperemic MBFCT for detecting obstructive coronary artery disease (CAD) in per-patient and per-vessel analysis, and their relations with the severity of CAD burden.Adenosine stressed and rest dynamic myocardial perfusion MDCT were prospectively performed in patients with known or suspected CAD. Per-patient and per-vessel MBFCT were estimated from dynamic perfusion images in rest and hyperemic phases, and per-patient and per-vessel CFRCT were calculated from the ratio of rest and hyperemic MBFCT. Degree of stenosis was evaluated by coronary CT angiography (CTA) and invasive coronary angiography (ICA). Obstructive stenosis was defined as ≥70% stenosis in ICA. CAD burden with MDCT was calculated by logarithm transformed coronary artery calcium (CAC) score and the CTA-adapted Leaman risk score (CT-LeSc). A logistic regression analysis was used to measure the receiver-operating characteristic curve and corresponding area under the curve (AUC) for the detection of obstructive CAD.Twenty-seven patients and 81 vessels were eligible for this study. Sixteen patients had obstructive CAD, and 31 vessels had obstructive stenosis. Using an optimal cutoff, the CFRCT and hyperemic MBFCT had the moderate diagnostic values in per-patient (AUC = 0.89 and 0.86, respectively) and per-vessel (AUC = 0.79 and 0.76, respectively). Per-patient CFRCT and hyperemic MBFCT exhibited a moderate inverse correlation with CAC score and the CT-LeSc.Per-patient and per-vessel CFRCT as well as hyperemic MBFCT had moderate diagnostic value for detecting obstructive CAD. These per-patient values exhibited a moderate inverse correlation with CAD burden. CFRCT and hyperemic MBFCT might add quantitative functional information for evaluating patients with CAD.