Quantitative assessment of left ventricular mechanical dyssynchrony using cine cardiovascular magnetic resonance imaging: Inter-study reproducibility.

OBJECTIVES: To determine the inter-study reproducibility of left ventricular (LV) mechanical dyssynchrony measures based on standard cardiovascular magnetic resonance (CMR) cine images. DESIGN: Steady-state free precession (SSFP) LV short-axis stacks and three long-axes were acquired on the same day at three time points. Circumferential strain systolic dyssynchrony indexes (SDI), area-SDI as well as circumferential and radial uniformity ratio estimates (CURE and RURE, respectively) were derived from CMR myocardial feature-tracking (CMR-FT) based on the tracking of three SSFP short-axis planes. Furthermore, 4D-LV-analysis based on SSFP short-axis stacks and longitudinal planes was performed to quantify 4D-volume-SDI. SETTING: A single-centre London teaching hospital. PARTICIPANTS: 16 healthy volunteers. MAIN OUTCOME MEASURES: Inter-study reproducibility between the repeated exams. RESULTS: CURE and RURE as well as 4D-volume-SDI showed good inter-study reproducibility (coefficient of variation [CoV] 6.4%-12.9%). Circumferential strain and area-SDI showed higher variability between the repeated measurements (CoV 24.9%-37.5%). Uniformity ratio estimates showed the lowest inter-study variability (CoV 6.4%-8.5%). CONCLUSIONS: Derivation of LV mechanical dyssynchrony measures from standard cine images is feasible using CMR-FT and 4D-LV-analysis tools. Uniformity ratio estimates and 4D-volume-SDI showed good inter-study reproducibility. Their clinical value should next be explored in patients who potentially benefit from cardiac resynchronization therapy.

The assessment of ischaemic burden: validation of a functional jeopardy score against cardiovascular magnetic resonance perfusion imaging.

AIMS: This study assesses the relationship between classical anatomical jeopardy scores, functional jeopardy scores (combined anatomical and haemodynamic data), and the extent of ischaemia identified on cardiovascular magnetic resonance (CMR) perfusion imaging. METHODS AND RESULTS: In 42 patients with stable angina and suspected coronary artery disease (CAD), CMR perfusion imaging was performed. Fractional Flow Reserve (FFR) was measured in vessels with ≥50 % stenosis. The APPROACH and BCIS jeopardy scores were calculated based on QCA results with both a 70 % (APP70 and BCIS70) and a 50 % stenosis (APP50, and BCIS50) used as the threshold for significance, as well as after integration of FFR and compared with the extent of ischaemia identified on CMR. The correlation between the extent of ischaemia measured by CMR and the anatomical jeopardy scores was moderate (APPROACH: r = 0.58; BCIS: r = 0.48, p = 0.001). Integrating physiological information improved this significantly to r = 0.82, p = 0.0001 for APPROACH and r = 0.82, p = 0.0001 for BCIS scores (z-statistic = -2.04, p = 0.04; z-statistic = -2.63, p = 0.009). In relation to CMR, the APPROACH and BCIS scores overestimated the volume of ischaemic myocardium by 29.2 and 25.2 %, respectively, which was reduced to 12.8 and 12 % after integrating functional data. CONCLUSIONS: Anatomical and functional jeopardy scores overestimate ischaemic burden when compared to CMR. Integrating physiological information from FFR to generate a functional score improves ischaemic burden estimation.

Inter-study reproducibility of left ventricular torsion and torsion rate quantification using MR myocardial feature tracking.

BACKGROUND: To determine the inter-study reproducibility of MR feature tracking (MR-FT) derived left ventricular (LV) torsion and torsion rates for a combined assessment of systolic and diastolic myocardial function. METHODS: Steady-state free precession (SSFP) cine LV short-axis stacks were acquired at 9:00 (Exam A), 9:30 (Exam B), and 14:00 (Exam C) in 16 healthy volunteers at 3 Tesla. SSFP images were analyzed offline using MR-FT to assess rotational displacement in apical and basal slices. Global peak torsion, peak systolic and peak diastolic torsion rates were calculated using different definitions ("twist", "normalized twist" and "circumferential-longitudinal (CL) shear angle"). Exam A and B were compared to assess the inter-study reproducibility. Morning and afternoon scans were compared to address possible diurnal variation. RESULTS: The different methods showed good inter-study reproducibility for global peak torsion (intraclass correlation coefficient [ICC]: 0.90-0.92; coefficient of variation [CoV]: 19.0-20.3%) and global peak systolic torsion rate (ICC: 0.82-0.84; CoV: 25.9-29.0%). Conversely, global peak diastolic torsion rate showed little inter-study reproducibility (ICC: 0.34-0.47; CoV: 40.8-45.5%). Global peak torsion as determined by the CL shear angle showed the best inter-study reproducibility (ICC: 0.90;CoV: 19.0%). MR-FT results were not measurably affected by diurnal variation between morning and afternoon scans (CL shear angle: 4.8 ± 1.4°, 4.8 ± 1.5°, and 4.1 ± 1.6° for Exam A, B, and C, respectively; P = 0.21). CONCLUSION: MR-FT based derivation of myocardial peak torsion and peak systolic torsion rate has high inter-study reproducibility as opposed to peak diastolic torsion rate. The CL shear angle was the most reproducible parameter independently of cardiac anatomy and may develop into a robust tool to quantify cardiac rotational mechanics in longitudinal MR-FT patient studies.

Quantification of atrial dynamics using cardiovascular magnetic resonance: inter-study reproducibility.

BACKGROUND: Cardiovascular magnetic resonance (CMR) offers quantification of phasic atrial functions based on volumetric assessment and more recently, on CMR feature tracking (CMR-FT) quantitative strain and strain rate (SR) deformation imaging. Inter-study reproducibility is a key requirement for longitudinal studies but has not been defined for CMR-based quantification of left atrial (LA) and right atrial (RA) dynamics. METHODS: Long-axis 2- and 4-chamber cine images were acquired at 9:00 (Exam A), 9:30 (Exam B) and 14:00 (Exam C) in 16 healthy volunteers. LA and RA reservoir, conduit and contractile booster pump functions were quantified by volumetric indexes as derived from fractional volume changes and by strain and SR as derived from CMR-FT. Exam A and B were compared to assess the inter-study reproducibility. Morning and afternoon scans were compared to address possible diurnal variation of atrial function. RESULTS: Inter-study reproducibility was within acceptable limits for all LA and RA volumetric, strain and SR parameters. Inter-study reproducibility was better for volumetric indexes and strain than for SR parameters and better for LA than for RA dynamics. For the LA, reservoir function showed the best reproducibility (intraclass correlation coefficient (ICC) 0.94-0.97, coefficient of variation (CoV) 4.5-8.2%), followed by conduit (ICC 0.78-0.97, CoV 8.2-18.5%) and booster pump function (ICC 0.71-0.95, CoV 18.3-22.7). Similarly, for the RA, reproducibility was best for reservoir function (ICC 0.76-0.96, CoV 7.5-24.0%) followed by conduit (ICC 0.67-0.91, CoV 13.9-35.9) and booster pump function (ICC 0.73-0.90, CoV 19.4-32.3). Atrial dynamics were not measurably affected by diurnal variation between morning and afternoon scans. CONCLUSIONS: Inter-study reproducibility for CMR-based derivation of LA and RA functions is acceptable using either volumetric, strain or SR parameters with LA function showing higher reproducibility than RA function assessment. Amongst the different functional components, reservoir function is most reproducibly assessed by either technique followed by conduit and booster pump function, which needs to be considered in future longitudinal research studies.

Multicenter evaluation of dynamic three-dimensional magnetic resonance myocardial perfusion imaging for the detection of coronary artery disease defined by fractional flow reserve.

BACKGROUND: First-pass myocardial perfusion cardiovascular magnetic resonance (CMR) imaging yields high diagnostic accuracy for the detection of coronary artery disease (CAD). However, standard 2D multislice CMR perfusion techniques provide only limited cardiac coverage, and hence considerable assumptions are required to assess myocardial ischemic burden. The aim of this prospective study was to assess the diagnostic performance of 3D myocardial perfusion CMR to detect functionally relevant CAD with fractional flow reserve (FFR) as a reference standard in a multicenter setting. METHODS AND RESULTS: A total of 155 patients with suspected CAD listed for coronary angiography with FFR were prospectively enrolled from 5 European centers. 3D perfusion CMR was acquired on 3T MR systems from a single vendor under adenosine stress and at rest. All CMR perfusion analyses were performed in a central laboratory and blinded to all clinical data. One hundred fifty patients were successfully examined (mean age 62.9±10 years, 45 female). The prevalence of CAD defined by FFR (<0.8) was 56.7% (85 of 150 patients). The sensitivity and specificity of 3D perfusion CMR were 84.7% and 90.8% relative to the FFR reference. Comparison to quantitative coronary angiography (≥50%) yielded a prevalence of 65.3%, sensitivity and specificity of 76.5% and 94.2%, respectively. CONCLUSIONS: In this multicenter study, 3D myocardial perfusion CMR proved highly diagnostic for the detection of significant CAD as defined by FFR.

Three-dimensional balanced steady state free precession myocardial perfusion cardiovascular magnetic resonance at 3T using dual-source parallel RF transmission: initial experience.

BACKGROUND: The purpose of this study was to establish the feasibility of three-dimensional (3D) balanced steady-state-free-precession (bSSFP) myocardial perfusion cardiovascular magnetic resonance (CMR) at 3T using local RF shimming with dual-source RF transmission, and to compare it with spoiled gradient echo (TGRE) acquisition. METHODS: Dynamic contrast-enhanced 3D bSSFP perfusion imaging was performed on a 3T MRI scanner equipped with dual-source RF transmission technology. Images were reconstructed using k-space and time broad-use linear acquisition speed-up technique (k-t BLAST) and compartment based principle component analysis (k-t PCA). RESULTS: In phantoms and volunteers, local RF shimming with dual source RF transmission significantly improved B1 field homogeneity compared with single source transmission (P=0.01). 3D bSSFP showed improved signal-to-noise, contrast-to-noise and signal homogeneity compared with 3D TGRE (29.8 vs 26.9, P=0.045; 23.2 vs 21.6, P=0.049; 14.9% vs 12.4%, p=0.002, respectively). Image quality was similar between bSSFP and TGRE but there were more dark rim artefacts with bSSFP. k-t PCA reconstruction reduced artefacts for both sequences compared with k-t BLAST. In a subset of five patients, both methods correctly identified those with coronary artery disease. CONCLUSION: Three-dimensional bSSFP myocardial perfusion CMR using local RF shimming with dual source parallel RF transmission at 3T is feasible and improves signal characteristics compared with TGRE. Image artefact remains an important limitation of bSSFP imaging at 3T but can be reduced with k-t PCA.

Ischemic burden by 3-dimensional myocardial perfusion cardiovascular magnetic resonance: comparison with myocardial perfusion scintigraphy.

BACKGROUND: The extent and severity of ischemia on myocardial perfusion scintigraphy (MPS) is commonly used to risk-stratify patients with coronary artery disease. Estimation of ischemic burden by cardiovascular magnetic resonance (CMR) with conventional 2-dimensional myocardial perfusion methods is limited by incomplete cardiac coverage. More recently developed 3-dimensional (3D) myocardial perfusion CMR, however, provides whole-heart coverage. The aim of this study was to compare ischemic burden on 3D myocardial perfusion CMR with (99m)Tc-tetrofosmin MPS. METHODS AND RESULTS: Forty-five patients who had undergone clinically indicated MPS underwent rest and adenosine stress 3D myocardial perfusion and late gadolinium enhancement CMR. Summed stress and rest scores were calculated for MPS and CMR using a 17-segment model and expressed as a percentage of the maximal possible score. Ischemic burden was defined as the difference between stress and rest scores. 3D myocardial perfusion CMR and MPS agreed in 38 of the 45 patients for the detection of any inducible ischemia. The mean ischemic burden for MPS and CMR was similar (7.5±8.9% versus 6.8±9.5%, respectively, P=0.82) with a strong correlation between techniques (rs=0.70, P<0.001). In a subset of 33 patients who underwent clinically indicated invasive coronary angiography, sensitivities and specificities of the 2 techniques to detect angiographic coronary artery disease were similar (McNemar P=0.45). CONCLUSIONS: 3D myocardial perfusion CMR is an alternative to MPS for detecting the presence and rating the severity of ischemia.

Hyperemic stress myocardial perfusion cardiovascular magnetic resonance in mice at 3 Tesla: initial experience and validation against microspheres.

BACKGROUND: Dynamic first pass contrast-enhanced myocardial perfusion is the standard CMR method for the estimation of myocardial blood flow (MBF) and MBF reserve in man, but it is challenging in rodents because of the high temporal and spatial resolution requirements. Hyperemic first pass myocardial perfusion CMR during vasodilator stress in mice has not been reported. METHODS: Five C57BL/6 J mice were scanned on a clinical 3.0 Tesla Achieva system (Philips Healthcare, Netherlands). Vasodilator stress was induced via a tail vein catheter with an injection of dipyridamole. Dynamic contrast-enhanced perfusion imaging (Gadobutrol 0.1 mmol/kg) was based on a saturation recovery spoiled gradient echo method with 10-fold k-space and time domain undersampling (k-t PCA). One week later the mice underwent repeat anaesthesia and LV injections of fluorescent microspheres at rest and at stress. Microspheres were analysed using confocal microscopy and fluorescence-activated cell sorting. RESULTS: Mean MBF at rest measured by Fermi-function constrained deconvolution was 4.1 ± 0.5 ml/g/min and increased to 9.6 ± 2.5 ml/g/min during dipyridamole stress (P = 0.005). The myocardial perfusion reserve was 2.4 ± 0.54. The mean count ratio of stress to rest microspheres was 2.4 ± 0.51 using confocal microscopy and 2.6 ± 0.46 using fluorescence. There was good agreement between cardiovascular magnetic resonance CMR and microspheres with no significant difference (P = 0.84). CONCLUSION: First-pass myocardial stress perfusion CMR in a mouse model is feasible at 3 Tesla. Rest and stress MBF values were consistent with existing literature and perfusion reserve correlated closely to microsphere analysis. Data were acquired on a 3 Tesla scanner using an approach similar to clinical acquisition protocols, potentially facilitating translation of imaging findings between rodent and human studies.

Coronary wave energy: a novel predictor of functional recovery after myocardial infarction.

BACKGROUND: Revascularization after acute coronary syndromes provides prognostic benefit, provided that the subtended myocardium is viable. The microcirculation and contractility of the subtended myocardium affect propagation of coronary flow, which can be characterized by wave intensity analysis. The study objective was to determine in acute coronary syndromes whether early wave intensity analysis-derived microcirculatory (backward) expansion wave energy predicts late viability, defined by functional recovery. METHODS AND RESULTS: Thirty-one patients (58±11 years) were enrolled after non-ST elevation myocardial infarction. Regional left ventricular function and late-gadolinium enhancement were assessed by cardiac magnetic resonance imaging, before and 3 months after revascularization. The backward-traveling (microcirculatory) expansion wave was derived from wave intensity analysis of phasic coronary pressure and velocity in the infarct-related artery, whereas mean values were used to calculate hyperemic microvascular resistance. Twelve-hour troponin T, left ventricular ejection fraction, and percentage late-gadolinium enhancement mass were 1.35±1.21 µg/L, 56±11%, and 8.4±6.0%, respectively. The infarct-related artery backward-traveling (microcirculatory) expansion wave was inversely correlated with late-gadolinium enhancement infarct mass (r=-0.81; P<0.0001) and strongly predicted regional left ventricular recovery (r=0.68; P=0.001). By receiver operating characteristic analysis, a backward-traveling (microcirculatory) expansion wave threshold of 2.8 W m(-2) s(-2)×10(5) predicted functional recovery with sensitivity and specificity of 0.91 and 0.82 (AUC 0.88). Hyperemic microvascular resistance correlated with late-gadolinium enhancement mass (r=0.48; P=0.03) but not left ventricular recovery (r=-0.34; P=0.07). CONCLUSIONS: The microcirculation-derived backward expansion wave is a new index that correlates with the magnitude and location of infarction, which may allow for the prediction of functional myocardial recovery. Coronary wave intensity analysis may facilitate myocardial viability assessment during cardiac catheterization.

The intra-observer reproducibility of cardiovascular magnetic resonance myocardial feature tracking strain assessment is independent of field strength.

BACKGROUND: Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a promising novel method for quantification of myocardial wall mechanics from standard steady-state free precession (SSFP) images. We sought to determine whether magnetic field strength affects the intra-observer reproducibility of CMR-FT strain analysis. METHODS: We studied 2 groups, each consisting of 10 healthy subjects, at 1.5 T or 3T Analysis was performed at baseline and after 4 weeks using dedicated CMR-FT prototype software (Tomtec, Germany) to analyze standard SSFP cine images. Right ventricular (RV) and left ventricular (LV) longitudinal strain (Ell(RV) and Ell(LV)) and LV long-axis radial strain (Err(LAX)) were derived from the 4-chamber cine, and LV short-axis circumferential and radial strains (Ecc(SAX), Err(SAX)) from the short-axis orientation. Strain parameters were assessed together with LV ejection fraction (EF) and volumes. Intra-observer reproducibility was determined by comparing the first and the second analysis in both groups. RESULTS: In all volunteers resting strain parameters were successfully derived from the SSFP images. There was no difference in strain parameters, volumes and EF between field strengths (p>0.05). In general Ecc(SAX) was the most reproducible strain parameter as determined by the coefficient of variation (CV) at 1.5 T (CV 13.3% and 46% global and segmental respectively) and 3T (CV 17.2% and 31.1% global and segmental respectively). The least reproducible parameter was Ell(RV) (CV 1.5 T 28.7% and 53.2%; 3T 43.5% and 63.3% global and segmental respectively). CONCLUSIONS: CMR-FT results are similar with reasonable intra-observer reproducibility in different groups of volunteers at 1.5 T and 3T. CMR-FT is a promising novel technique and our data indicate that results might be transferable between field strengths. However there is a considerable amount of segmental variability indicating that further refinements are needed before CMR-FT can be fully established in clinical routine for quantitative assessment of wall mechanics and strain.

Cardiovascular magnetic resonance myocardial feature tracking for quantitative viability assessment in ischemic cardiomyopathy.

BACKGROUND: Low dose dobutamine stress magnetic resonance imaging is valuable to assess viability in patients with ischemic cardiomyopathy. Analysis is usually qualitative with considerable operator dependency. The aim of the current study was to investigate the feasibility of cine images derived quantitative cardiac magnetic resonance (CMR) myocardial feature tracking (FT) strain parameters to assess viability in patients with ischemic cardiomyopathy. METHODS: 15 consecutive patients with ischemic cardiomyopathy referred for viability assessment were studied at 3T at rest and during low dose dobutamine stress (5 and 10µg/kg/min of dobutamine). Subendocardial and subepicardial circumferential (Eccendo and Eccepi) and radial (Err) strains were assessed using steady state free precession (SSFP) cine images orientated in 3 short axis slices covering 16 myocardial segments. RESULTS: Dysfunctional segments without scar (n=75) improved in all three strain parameters: Eccendo (Rest: -10.5±6.9; 5µg: -12.1±6.9; 10µg: -14.1±9.2; p<0.05), Eccepi (Rest: -7±4.8; 5µg: -8.2±5.5; 10µg: -9.1±5.9; p<0.05) and Err (Rest: 11.7±8.3; 5µg: 16±10.9; 10µg: 16.5±12.8; p<0.05). There was no response to dobutamine in dysfunctional segments with scar transmurality above 75% (n=6): Eccendo (Rest: -4.7±3.0; 5µg: -2.9±2.5; 10µg: -6.6±3.3; p=ns), Eccepi (Rest: -2.9±2.9; 5µg: -5.4±3.9; 10µg: -4.5±4.2; p=ns) and Err (Rest:9.5±5; 5µg:5.4±6.2; 10µg:4.9±3.3; p=ns). Circumferential strain (Eccendo, Eccepi) improved in all segments up to a transmurality of 75% (n=60; p<0.05). Err improved in segments <50% transmurality (n=45; p<0.05) and remained unchanged above 50% transmurality (n=21; p=ns). CONCLUSIONS: CMR-FT is a novel technique, which detects quantitative wall motion derived from SSFP cine imaging at rest and with low dose dobutamine stress. CMR-FT holds promise of quantitative assessment of viability in patients with ischemic cardiomyopathy.

Validation of dynamic 3-dimensional whole heart magnetic resonance myocardial perfusion imaging against fractional flow reserve for the detection of significant coronary artery disease.

OBJECTIVES: The goal of this study was to determine the diagnostic accuracy of dynamic 3-dimensional (3D) whole heart myocardial perfusion cardiovascular magnetic resonance (CMR) against invasively determined fractional flow reserve (FFR) and to establish the correlation between myocardium at risk defined by using the invasive Duke Jeopardy Score (DJS) and noninvasive 3D whole heart myocardial perfusion CMR. BACKGROUND: 3D whole heart myocardial perfusion CMR overcomes the limited spatial coverage of conventional two-dimensional perfusion CMR methods and allows estimation of the extent of ischemia. The method has shown good diagnostic accuracy for the detection of coronary artery disease (CAD) as defined by using quantitative coronary angiography. However, quantitative coronary angiography does not provide a functional assessment of CAD as available from pressure wire-derived FFR. In the catheter laboratory, the DJS can complement FFR to estimate the myocardium at risk. METHODS: Fifty-three patients referred for angiography underwent rest and adenosine stress 3D whole heart myocardial perfusion CMR at 3-T. Perfusion was scored visually on a patient and coronary territory basis, and ischemic burden was calculated by quantitative segmentation of the volume of hypoenhancement. FFR was measured in vessels with ≥50% severity stenosis and an FFR <0.75 considered as hemodynamically significant. The DJS was calculated from the coronary angiograms to quantify the myocardium at risk. RESULTS: FFR was measured in 64 of 159 coronary vessels, and 39 had an FFR <0.75. Sensitivity, specificity, and diagnostic accuracy of CMR for the detection of significant CAD were 91%, 90%, and 91%, on a patient basis and 79%, 92%, and 88%, respectively, by coronary territory. There was a strong correlation between the DJS and ischemic burden on CMR (p < 0.0001; Pearson's r = 0.82). CONCLUSIONS: 3D whole heart myocardial perfusion CMR accurately detects functionally significant CAD as defined by using FFR and provides an assessment of ischemic burden in agreement with the invasive DJS. The accurate detection of significant CAD combined with an estimation of ischemic burden by using 3D myocardial perfusion CMR holds promise for noninvasive guidance of therapy and risk stratification of patients with CAD.

Inter-study reproducibility of cardiovascular magnetic resonance myocardial feature tracking.

BACKGROUND: Cardiovascular magnetic resonance myocardial feature tracking (CMR-FT) is a recently described method of post processing routine cine acquisitions which aims to provide quantitative measurements of circumferentially and radially directed ventricular wall strain. Inter-study reproducibility is important for serial assessments however has not been defined for CMR-FT. METHODS: 16 healthy volunteers were imaged 3 times within a single day. The first examination was performed at 0900 after fasting and was immediately followed by the second. The third, non-fasting scan, was performed at 1400.CMR-FT measures of segmental and global strain parameters were calculated. Left ventricular (LV) circumferential and radial strain were determined in the short axis orientation (Ecc(SAX) and Err(SAX) respectively). LV and right ventricular longitudinal strain and LV radial strain were determined from the 4-chamber orientation (Ell(LV), Ell(RV), and Err(LAX) respectively). LV volumes and function were also analysed.Inter-study reproducibility and study sample sizes required to demonstrate 5% changes in absolute strain were determined by comparison of the first and second exams. The third exam was used to determine whether diurnal variation affected reproducibility. RESULTS: CMR-FT strain analysis inter-study reproducibility was variable. Global strain assessment was more reproducible than segmental analysis. Overall Ecc(SAX) was the most reproducible measure of strain: coefficient of variation (CV) 38% and 20.3% and intraclass correlation coefficient (ICC) 0.68 (0.55-0.78) and 0.7 (0.32-0.89) for segmental and global analysis respectively. The least reproducible segmental measure was Ell(RV): CV 60% and ICC 0.56 (0.41-0.69) whilst the least reproducible global measure was Err(LAX): CV 33.3% and ICC 0.44 (0-0.77). Variable reproducibility was also reflected in the calculated sample sizes, which ranged from 11 (global Ecc(SAX)) to 156 subjects (segmental Ell(RV)). The reproducibility of LV volumes and function was excellent. There was no diurnal variation in global strain or LV volumetric measurements. CONCLUSIONS: Inter-study reproducibility of CMR-FT varied between different parameters, as summarized above and was better for global rather than segmental analysis. It was not measurably affected by diurnal variation. CMR-FT may have potential for quantitative wall motion analysis with applications in patient management and clinical trials. However, inter-study reproducibility was relatively poor for segmental and long axis analyses of strain, which have yet to be validated, and may benefit from further development.

Quantitative cardiovascular magnetic resonance perfusion imaging: inter-study reproducibility.

AIMS: To evaluate the inter-study reproducibility of quantitative cardiovascular magnetic resonance (CMR) myocardial perfusion imaging and the influence of diurnal variation on perfusion. Data on these are limited, despite being crucially important for performing serial examinations both in clinical practice and in trials. METHODS AND RESULTS: Sixteen healthy volunteers underwent high-resolution 3 T perfusion imaging three times during a single day to evaluate inter-study reproducibility and the effects of diurnal variation. Absolute perfusion was determined in each coronary artery territory and globally by Fermi constrained deconvolution of myocardial signal intensity curves. Left ventricular (LV) volumes and function were also calculated. Eleven full data sets were suitable for quantitative perfusion analysis. Global rest and stress perfusion and myocardial perfusion reserve (MPR) were 0.6 ± 0.1 and 2.5 ± 0.5 mL/min/g and 4.3 ± 0.9, respectively, for the first scan and were 0.5 ± 0.2 and 2.1 ± 0.5 mL/min/g and 4.2 ± 1.2 for the second (P= 0.1, 0.19, and 0.37, respectively). Inter-study reproducibility was moderate. The coefficient of variation (CV) was 16.0, 26.8, and 23.9% for global rest and stress perfusion and MPR, respectively. The corresponding territorial CVs were 27.5, 35.2, and 33.5%. The reproducibility of LV volumes and function was excellent (CV 4, 7.7, and 4.6% for end-diastolic volume, end-systolic volume, and ejection fraction, respectively). There were no significant detectable diurnal variations in perfusion or LV volumes and function (P≥ 0.05 for all). CONCLUSION: The inter-study reproducibility of quantitative myocardial perfusion is reasonable and best for global rest perfusion. No significant diurnal variation in perfusion was observed.