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Quantification of myocardial blood flow using non-electrocardiogram-triggered MRI with three-slice coverage.

ABSTRACT: Accurate quantification of myocardial perfusion is dependent on reliable electrocardiogram (ECG) triggering. Measuring myocardial blood flow (MBF) in patients with arrhythmias or poor ECGs is currently infeasible with MR. The purpose of this study was to demonstrate the feasibility of a non-ECG-triggered method with clinically useful three-slice ventricular coverage for measurement of MBF in healthy volunteers.A saturation recovery magnetization-prepared gradient recalled echo acquisition was continuously repeated during first-pass imaging. A slice-interleaved radial trajectory was employed to enable image-based retrospective triggering. The arterial input function was generated using a beat-by-beat T1 estimation method. The proposed technique was validated against a conventional ECG-triggered dual-bolus technique in 10 healthy volunteers. The technique was further demonstrated under adenosine stress in 12 healthy volunteers.The proposed method produced MBF with no significant difference compared with the ECG-triggered technique. The proposed method yielded mean myocardial perfusion reserve comparable to published literature.We have developed a non-ECG-triggered quantitative perfusion imaging method. In this preliminary study, our results demonstrate that our method yields comparable MBF compared with the conventional ECG-triggered method and that it is feasible for stress imaging.

SUBMITTER: Chen D

PROVIDER: S-EPMC4766039 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Quantification of myocardial blood flow using non-electrocardiogram-triggered MRI with three-slice coverage.

Chen David D Sharif Behzad B Bi Xiaoming X Wei Janet J Thomson Louise E J LE Bairey Merz C Noel CN Berman Daniel S DS Li Debiao D

Magnetic resonance in medicine 20150608 5

<h4>Purpose</h4>Accurate quantification of myocardial perfusion is dependent on reliable electrocardiogram (ECG) triggering. Measuring myocardial blood flow (MBF) in patients with arrhythmias or poor ECGs is currently infeasible with MR. The purpose of this study was to demonstrate the feasibility of a non-ECG-triggered method with clinically useful three-slice ventricular coverage for measurement of MBF in healthy volunteers.<h4>Methods</h4>A saturation recovery magnetization-prepared gradient ...[more]

PMID: 26059326

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Project description:BackgroundDual-venc 4D flow MRI, recently introduced for the assessment of intracranial hemodynamics, may provide a promising complementary approach to well-established tools such as transcranial Doppler ultrasound (TCD) and overcome some of their disadvantages. However, data comparing intracranial flow measures from dual-venc 4D flow MRI and TCD are lacking.PurposeTo compare cerebral blood flow velocity measures derived from dual-venc 4D flow MRI and TCD.Study typeProspective cohort.SubjectsA total of 25 healthy participants (56 ± 4 years old, 44% female).Field strength/sequenceA 3 T/dual-venc 4D flow MRI using a time-resolved three-dimensional phase-contrast sequence with three-dimensional velocity encoding.AssessmentPeak velocity measurements in bilateral middle cerebral arteries (MCA) were quantified from dual-venc 4D flow MRI and TCD. The MRI data were quantified by two independent observers (S.M and Y.M.) and TCD was performed by a trained technician (A.L.M.). We assessed the agreement between 4D flow MRI and TCD measures, and the interobserver agreement of 4D flow MRI measurements.Statistical testsPeak velocity from MRI and TCD was compared using Bland-Altman analysis and coefficient of variance. Intraclass correlation coefficient (ICC) was used to assess MRI interobserver agreement. A P value < 0.05 was considered statistically significant.ResultsThere was excellent interobserver agreement in dual-venc 4D flow MRI-based measurements of peak velocity in bilateral MCA (ICC = 0.97 and 0.96 for the left and right MCA, respectively). Dual-venc 4D flow MRI significantly underestimated peak velocity in the left and right MCA compared to TCD (bias = 0.13 [0.59, -0.33] m/sec and 0.15 [0.47, -0.17] m/sec, respectively). The coefficient of variance between dual-venc 4D flow MRI and TCD measurements was 26% for the left MCA and 22% for the right MCA.Data conclusionThere was excellent interobserver agreement for the assessment of MCA peak velocity using dual-venc 4D flow MRI, and ≤20% under-estimation compared with TCD.Evidence level3 TECHNICAL EFFICACY: Stage 2.

Project description:PURPOSE:Dynamic contrast enhanced MRI of the heart typically acquires 2-4 short-axis (SA) slices to detect and characterize coronary artery disease. This acquisition scheme is limited by incomplete coverage of the left ventricle. We studied the feasibility of using radial simultaneous multi-slice (SMS) technique to achieve SA, 2-chamber and/or 4-chamber long-axis (2CH LA and/or 4CH LA) coverage with and without electrocardiography (ECG) gating using a motion-robust reconstruction framework. METHODS:12 subjects were scanned at rest and/or stress, free breathing, with or without ECG gating. Multiple sets of radial SMS k-space were acquired within each cardiac cycle, and each SMS set sampled 3 parallel slices that were either SA, 2CH LA, or 4CH LA slices. The radial data was interpolated onto Cartesian space using an SMS GRAPPA operator gridding method. Self-gating and respiratory states binning of the data were done. The binning information as well as a pixel tracking spatiotemporal constrained reconstruction method were applied to obtain motion-robust image reconstructions. Reconstructions with and without the pixel tracking method were compared for signal-to-noise ratio and contrast-to-noise ratio. RESULTS:Full coverage of the heart (at least 3 SA and 3 LA slices) during the first pass of contrast at every heartbeat was achieved by using the radial SMS acquisition. The proposed pixel tracking reconstruction improves the average SNR and CNR by 21% and 30% respectively, and reduces temporal blurring for both gated and ungated acquisitions. CONCLUSION:Acquiring simultaneous multi-slice SA, 2CH LA and/or 4CH LA myocardial perfusion images in every heartbeat is feasible in both gated and ungated acquisitions. This can add confidence when detecting and characterizing coronary artery disease by revealing ischemia in different views, and by providing apical coverage that is improved relative to SA slices alone. The proposed pixel tracking framework improves the reconstruction while adding little computational cost.

Project description:BackgroundQuantification of myocardial blood flow (MBF) from dynamic contrast-enhanced (DCE) MRI can be performed using a signal intensity model that incorporates T1 values of blood and myocardium.PurposeTo assess the impact of T1 values on pixelwise MBF quantification, specifically to evaluate the influence of 1) study population-averaged vs. subject-specific, 2) diastolic vs. systolic, and 3) regional vs. global myocardial T1 values.Study typeProspective.SubjectsFifteen patients with chronic coronary heart disease.Field strength/sequence3T; modified Look-Locker inversion recovery for T1 mapping and saturation recovery gradient echo for DCE imaging, both acquired in a mid-ventricular short-axis slice in systole and diastole.AssessmentMBF was estimated using Fermi modeling and signal intensity nonlinearity correction with different T1 values: study population-averaged blood and myocardial, subject-specific systolic and diastolic, and segmental T1 values. Myocardial segments with perfusion deficits were identified visually from DCE series.Statistical testsThe relationships between MBF parameters derived by different methods were analyzed by Bland-Altman analysis; corresponding mean values were compared by t-test.ResultsUsing subject-specific diastolic T1 values, global diastolic MBF was 0.61?±?0.13?mL/(min·g). It did not differ from global MBF derived from the study population-averaged T1 (P = 0.88), but the standard deviation of differences was large (0.07?mL/(min·g), 11% of mean MBF). Global diastolic and systolic MBF did not differ (P = 0.12), whereas global diastolic MBF using systolic (0.62?±?0.13?mL/(min·g)) and diastolic T1 values differed (P?<?0.05). If regional instead of global T1 values were used, segmental MBF was lower in segments with perfusion deficits (bias = -0.03?mL/(min·g), -7% of mean MBF, P?<?0.05) but higher in segments without perfusion deficits (bias = 0.01?mL/(min·g), 1% of mean MBF, P?<?0.05).Data conclusionWhereas cardiac phase-specific T1 values have a minor impact on MBF estimates, subject-specific and myocardial segment-specific T1 values substantially affect MBF quantification.Level of evidence3 TECHNICAL EFFICACY STAGE: 3.

Dataset Information

Quantification of myocardial blood flow using non-electrocardiogram-triggered MRI with three-slice coverage.

Publications

Quantification of myocardial blood flow using non-electrocardiogram-triggered MRI with three-slice coverage.

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