Myocardial Perfusion MRI Research Articles

Comparison of the cost-effectiveness of stress myocardial perfusion MRI and SPECT in patients with suspected coronary artery disease

Our aim in this study was to perform a cost-effectiveness analysis (CEA) to compare myocardial perfusion magnetic resonance imaging (p-MRI) and single photon emission computed tomography (SPECT) in the Japanese setting. The CEA of p-MRI and SPECT was performed from the payer's perspective. The subjects were outpatients who had chest pain, had no history of myocardial infarction, and showed normal or equivocal stress electrocardiogram findings. The costs of imaging techniques and treatments were assessed with the use of reimbursements of medical fees from Japanese healthcare insurance for the year 2007. Clinical effectiveness was defined in terms of the percent correct diagnosis of coronary artery disease (CAD). Data from published studies provided probabilities for the CEA, including the sensitivity and specificity of each imaging modality. We evaluated the cost-effectiveness ratio (CER) of p-MRI and SPECT using a decision tree model and compared the two. The CERs for diagnosis of CAD by p-MRI and SPECT were 1,988.2 and 2,582.0 Japanese Yen (JPY), respectively. The CERs for diagnosis and treatment of CAD by p-MRI and SPECT were 7,066.1 and 7,172.2 JPY, respectively. At a pre-test likelihood of CAD of 20-70 %, the CERs for diagnosis of CAD by p-MRI and SPECT were 1,476.8-3,364.3 and 2,107.3-3,957.7 JPY, respectively. For outpatients with chest pain, p-MRI had good clinical effectiveness and cost-effectiveness compared with SPECT. In the management of patients with suspected CAD, p-MRI is as useful as SPECT.

Three‐dimensional first‐pass myocardial perfusion MRI using a stack‐of‐spirals acquisition

Three-dimensional cardiac magnetic resonance perfusion imaging is promising for the precise sizing of defects and for providing high perfusion contrast, but remains an experimental approach primarily due to the need for large-dimensional encoding, which, for traditional 3DFT imaging, requires either impractical acceleration factors or sacrifices in spatial resolution. We demonstrated the feasibility of rapid three-dimensional cardiac magnetic resonance perfusion imaging using a stack-of-spirals acquisition accelerated by non-Cartesian k-t SENSE, which enables entire myocardial coverage with an in-plane resolution of 2.4 mm. The optimal undersampling pattern was used to achieve the largest separation between true and aliased signals, which is a prerequisite for k-t SENSE reconstruction. Flip angle and saturation recovery time were chosen to ensure negligible magnetization variation during the transient data acquisition. We compared the proposed three-dimensional perfusion method with the standard 2DFT approach by consecutively acquiring both data during each R-R interval in cardiac patients. The mean and standard deviation of the correlation coefficients between time intensity curves of three-dimensional versus 2DFT were 0.94 and 0.06 across seven subjects. The linear correlation between the two sets of upslope values was significant (r = 0.78, P < 0.05).

Myocardial perfusion MRI with SW-CG-HYPR: a comparison to conventional SR-Turbo-FLASH and x-ray angiography in patients with suspected coronary artery disease

Summary In the current study, we prospectively compared the diagnostic value of SW-CG-HYPR and conventional SRTurbo-FLASH for myocardial perfusion MRI in patients with suspected CAD. Compared with conventional SRTurbo-FLASH, SW-CG-HYPR allows increased spatial coverage (whole left ventricular coverage), improved temporal and spatial resolution and SNR, reduced motion artifacts and has higher diagnostic accuracy in patients with suspected CAD. Background A sliding-window (SW) conjugate-gradient (CG) highly constrained back-projection reconstruction (HYPR) (SW-CG-HYPR) technique has been developed for timeresolved myocardial perfusion imaging. Using this method, the acquisition time per cardiac cycle can be reduced dramatically while maintaining the temporal resolution of one frame per heartbeat in myocardial perfusion MRI, allowing increased spatial coverage (whole left ventricular coverage), improved temporal and spatial resolution and SNR, and reduced motion artifacts compared with the conventional SR-Turbo-FLASH sequence. However, the diagnostic accuracy of myocardial perfusion MRI with SW-CG-HYPR for detecting coronary artery disease (CAD) has not been directly compared to that with conventional SR-Turbo-FLASH. The purpose of this study was to prospectively compare the diagnostic value of SW-CG-HYPR and conventional SR-Turbo-FLASH for myocardial perfusion MRI in patients with suspected CAD. Methods

Evaluation of semi quantitative perfusion parameter maps generated based on a fully automated non-rigid motion correction during a first pass myocardial perfusion (FPMP) MRI

Summary The purpose of this study is to evaluate semi quantitative perfusion parameter maps generated based on a fully automated non-rigid motion correction during a first pass myocardial perfusion (FPMP) MRI in patients with suspected coronary artery disease (CAD) or coronary micro vascular disease (CMVD). Background FPMP MRI is commonly used to assess CAD and most recently to assess cardiac involvement in asymptomatic patients with CMVD such as systemic sclerosis and diabetes mellitus. FPMP MRI evaluation relies on visual inspection for qualitative analysis but quantitative analysis of rest and stress perfusion data is desired to improve diagnosis. One main challenge of qualitative analysis includes cardiac and respiratory motion. To minimize this challenge, ap reviously described inline, fully automated motion correction method [Xue, H MICCAI 2009] generates a motion corrected dataset as well as pixel-wise upslope maps. Using the image at a time point selected for peak signal change during the first pass of contrast agent as the template, all other time points were registered into the template coordinate system. We compare qualitatively and quantitatively the original free breathing images and motion correted images with the corresponding maps pixel-wise upslope maps in patients with suspected CAD or CMVD. Methods

Myocardial perfusion MRI using SW-CG-HYPR for the detection of coronary artery disease

In this work, we have prospectively examined the diagnostic value of adenosine-induced stress myocardial perfusion MRI using SW-CG-HYPR in 50 patients with suspected CAD. Using the high-resolution, whole left ventricle SW-CG-HYPR method, perfusion MRI was able to depict hemodynamically relevant coronary artery stenosis with an accuracy of 90% and 93% based on per-patient and per-vessel analyses, respectively, using x-ray coronary angiography as the reference standard.

Evaluation of fully automated motion corrected first pass myocardial perfusion MRI with semi quantitative perfusion parameter maps in patients with ischemic heart disease

Summary The purpose of the study is to evaluate a fully automated motion corrected first pass myocardial perfusion (FPMP) MRI with semi quantitative perfusion parameter maps in patients with suspected ischemic heart disease. Background Coronary heart disease is the leading cause of death and disability in the US. FPMP MRI is increasingly used to assess ischemic heart disease; however respiratory motion is one of the major problems for myocardial blood flow quantification. An algorithm for motion correction, surface coil correction, temporal denoising and robust pixel-wise parameter map generation model was previously desribed [Xue H et al MICCAI 2009).This work evaluates automated workflow in a clinical setting to diagnose ischemic heart disease comparing free breathing and motion correcteted images and corresponding pixel-wise parameter map. Methods Stress and rest FPMP images were acquired using a 1.5T scanner (MAGNETOM Avanto, Siemens Healthcare) in 39 patients with suspected ischemic heart disease. Short axis slices were acquired during infusion of 0.075 mMol/kg of Gadolinium (Magnevist, Bayer HealthCare Pharmaceuticals, USA) and adenosine (Adenoscan, AstellasPharma, USA) infusion (0.14 mg/kg/min; duration: 4 min) was administrated to induce stress. Free breathing, motion-corrected images and corresponding perfusion maps were assessed by 2 radiologists independently using the AHA 16 model and evaluated using a four point Likert scale (poor to excellent) to evaluate image quality and confidence level in presence or absence of hypo-perfusion regions. Upslope index of both free breathing and motion corrected images during stress and rest were manually calculated in nonischemic and ischemic areas and compared to the corresponding pixel-wise parameter map generated based on motion corrected images. FPMP MRI results were subsequently compared to coronary angiogram, stress echocardiography, or SPECT.

Influence of coronary flow profiles on bolus shape and quantitative myocardial perfusion MRI

Summary Simulations of the influence of contrast agent bolus dispersion on the shape of the contrast agent bolus and on quantification of myocardial blood flow (MBF) have been made using an exponential residue function model, and an computational fluid dynamics (CFD) approach. Based on the exponential residue function model, up to 20% underestimation of MBF appeared reasonable. CFD simulations showed that bolus dispersion occures in normal coronary vessels as well as in those with stenosis. However, bolus dispersion was smaller with stenosis than without. Background

Motion compensated reconstruction for myocardial perfusion MRI

Background Classical acceleration schemes for myocardial perfusion MRI like view sharing, k-t BLAST [Tsao et al. ‘03] are sensitive to motion artifacts which could arise in data with inconsistent gating and/or breathing motion. A natural approach to be robust to this is to estimate the motion and compensate for it during the recovery; to this end we proposed a novel joint motion estimation and reconstruction scheme in [Lingala et al. ‘11]. One goal of this work is to further validate it by recovering such data at considerable accelerations (R). In a 2nd goal, we apply it to recover images acquired with an ungated protocol [DiBella et al. ‘11]. This obtains data at a rapid rate without any gating to provide robustness to beat-beat variability. It also offers a high temporal resolution (~50ms), which ensures maximal information is obtained during the brief first pass. This resolution also means the cardiac motion is captured, akin to cine imaging. Here, we aim to benefit the reconstructions by compensating for this motion. We show its utility by comparisons with standard gridding reconstruction (GR) and sliding window (SW) algorithm.

Accelerated imaging of rest and stress myocardial perfusion MRI using multi-coil k-t SLR: a feasibility study

Background In myocardial perfusion imaging (MPI), highly accelerated acquisition can be used towards reducing the compromises in the image quality (spatio-temporal resolutions, volume coverage, SNR) routinely observed with the current clinical protocols. In this study, we demonstrate the feasibility of a recent accelerated dynamic MRI scheme, k-t SLR (based on sparse and low rank properties) (Lingala et al. ‘11) in free breathing MPI. k-t SLR exploits natural redundancy in MPI by using (a) the high degree of temporal correlations, and (b) the sparse properties of the images in appropriate transform domains (finite difference transforms along space and time). It poses the recovery as a spectral regularization problem, allowing for the use of fast optimization solvers and flexible non-Cartesian sampling schemes. Here, we also include information from multiple coils to improve data consistency in the recovery. We demonstrate high accelerations with both rest and stress data sets. Comparisons are made with existing schemes such as spatio-temporal constrained reconstruction (STCR, Adluru et al ‘09) and k-t SPARSE/ SENSE (Otazo et al ‘10). Methods A radial FLASH saturation recovery sequence (TR/ TE~2.5/1.3ms) was used. 3 slices with 72 rays uniformly spaced within a frame and offset between frames were acquired. Datasets for 3 normal subjects and 1 patient with disease were imaged in rest and adenosine stress. These 72 ray sets correspond to an acceleration of R ~ 3.4 compared to Nyquist sampling. Residual streaking was resolved in these sets by using a standard STCR algorithm and formed the ‘reference’ images. We performed retrospective undersampling using 21 rays (R~12) and 18 rays (R~14) respectively for the stress and rest sets and reconstructed with multi-coil k-t SLR, multi-coil STCR and multi-coil k-t SPARSE. Golden ratio, uniform and random sampling were respectively used for k-t SLR, STCR and k-t SPARSE/SENSE, based on experiments of which sampling pattern was best for each algorithm. Validation was based on two metrics that depict the accuracy of the myocardial perfusion dynamics (see fig 2). The first metric gives a measure of the myocardial slope while the second gives an aggregate measure of several factors such as peak enhancement, sensitivity to breathing motion and temporal blur. Results

Myocardial perfusion acquisition without magnetization preparation or gating

Current myocardial perfusion MRI acquisitions are performed with a saturation recovery sequence, in large part to minimize sensitivity to arrhythmia. A new approach is proposed here where the images are acquired ungated at steady state without use of a saturation pulse. The data are acquired continuously and reach steady state after the first few images. A confluence of advances has made this new paradigm of an ungated steady-state acquisition possible-very rapid undersampled readouts with new reconstruction technologies permit enough measurements that continuous acquisition becomes a feasible approach. Gating can be applied retrospectively from a logged electrocardiogram (ECG) or with self-gating methods. In this work, simulations and measurements in a concentration phantom are used to demonstrate that similar contrast and signal can be obtained with the standard saturation recovery and the proposed spoiled gradient echo (SPGR) acquisition. Specifically, for a flip angle of 14° and a saturation recovery time of 80 ms, similar signals are acquired over a range of T(1) s that reflect realistic myocardial tissue concentrations. Preliminary results in one subject are presented to show the potential of this new approach. The method may allow for cine cardiac perfusion and more signal-to-noise ratio-efficient acquisitions.

Abstract 17129: Altered Subendocardial Perfusion Reserve in Patients with Normal-High Blood Pressure Assessed by Quantitative Analysis of Myocardial Perfusion MRI

Background Myocardial perfusion reserve (MPR) reflects endothelial function of the coronary artery and can be altered by various atherosclerotic risk factors. We previously reported that hypertension is associated with impairment of MPR, especially subendocardial MPR. However, information is limited regarding the impact of normal-high blood pressure (systolic blood pressure (SBP) of 130-139mmHg, diastolic blood pressure (DBP) of 85-89mmHg, or both) on MPR. Purpose To determine if MPR was already altered in patients with normal-high blood pressure by using a quantitative analysis of stress-rest myocardial perfusion MRI. Method We studied 73 subjects without hypertension (SBP&lt;140mmHg and DBP&lt;90mmHg) who did not exhibit regional myocardial ischemia and myocardial scar on stress CMR study. Subjects were divided into two groups (Normal-high group: n=19, 68±9 year-old, 17 men; Normal-optimal group (SBP&lt;130mmHg and DBP&lt;85mmHg): n=54, 68±10 year-old, 33 men) according to blood pressure. Stress-rest myocardial perfusion MRI was acquired with blood signal saturation correction, and absolute subendocardial and epicardial myocardial blood flow (MBF) and MPR were quantified. MPR were calculated as stress MBF divided by rest MBF. Result The averaged transmural MPR in subjects with normal-high blood pressure was significantly lower than that in normal-optimal group.(2.74±1.61 vs. 3.80±2.03, p=0.043). When subepicardial MBF and subendocardial MBF were analyzed separately, MPR in subepicardial myocardium did not demonstrate significant difference between two groups (3.09±1.66 vs. 4.29±2.49, p=ns). In contrast, MPR in subendocardial myocardium was significantly reduced in the high-normal group than in the normal-optimal group. (2.57±1.51 vs. 3.65±1.66, p=0.015) Conclusion In the current study evaluating subjects without regional myocardial ischemia or significant coronary artery disease, subendocardial MPR was significantly decreased in the group with normal-high blood pressure. The result of this study suggests that endothelial function of the coronary artery is already altered in patients with normal-high blood pressure.

Quantification of myocardial blood flow using model based analysis of first‐pass perfusion MRI: Extraction fraction of Gd‐DTPA varies with myocardial blood flow in human myocardium

For the absolute quantification of myocardial blood flow (MBF), Patlak plot-derived K1 need to be converted to MBF by using the relation between the extraction fraction of gadolinium contrast agent and MBF. This study was conducted to determine the relation between extraction fraction of Gd-DTPA and MBF in human heart at rest and during stress. Thirty-four patients (19 men, mean age of 66.5 ± 11.0 years) with normal coronary arteries and no myocardial infarction were retrospectively evaluated. First-pass myocardial perfusion MRI during adenosine triphosphate stress and at rest was performed using a dual bolus approach to correct for saturation of the blood signal. Myocardial K1 was quantified by Patlak plot method. Mean MBF was determined from coronary sinus flow measured by phase contrast cine MRI and left ventricle mass measured by cine MRI. The extraction fraction of Gd-DTPA was calculated as the K1 divided by the mean MBF. The extraction fraction of Gd-DTPA was 0.46 ± 0.22 at rest and 0.32 ± 0.13 during stress (P < 0.001). The relationship between extraction fraction (E) and MBF in human myocardium can be approximated as E = 1 - exp(-(0.14 × MBF + 0.56)/MBF). The current results indicate that MBF can be accurately quantified by Patlak plot method of first-pass myocardial perfusion MRI by performing a correction of extraction fraction.

Pseudo ground truth based nonrigid registration of myocardial perfusion MRI

This paper presents a novel nonrigid registration method for myocardial perfusion magnetic resonance (MR) images. To overcome the rapid intensity change due to contrast enhancement, we propose to register the observed sequence to a pseudo ground truth, which is a motion/noise free sequence that is estimated from the observed one, and having almost identical intensity variations as the original sequence. The pseudo ground truth and the elastic deformation fields for the observed sequence are obtained by minimizing an energy functional integrating both the registration error and the spatiotemporal constraints on the pseudo ground truth in an expectation-maximization framework. We have tested the proposed nonrigid registration method on 20 cardiac perfusion MR scans. The proposed method successfully compensated the elastic deformation of the heart in most scans according to visual validation. For quantitative validation, we propagated manually drawn myocardial contours in one frame to other frames according to the deformation fields obtained by applying different registration methods. The root mean square distance between the propagated contour and the gold standard is 2.11mm if only global translation is compensated, and 1.87mm after nonrigid registration, as compared with 2.80mm for serial demons registration and 2.77mm for a free-form deformation approach using normalized mutual information as the similarity measure, both of which adversely increased the error due to misregistration.

Adenosine-induced stress myocardial perfusion MRI using SW-CG-HYPR with whole left ventricular coverage: comparison of results with X-ray angiography in patients with suspected CAD

Myocardial perfusion MRI with sliding-window conjugate-gradient HYPR (SW-CG-HYPR) allows increased spatial coverage (whole left ventricular coverage), resolution, signal-to-noise ratio and reduced motion artifacts. The accuracy of this technique for detecting coronary artery disease (CAD) has not been determined in a large number of patients.

ACR Appropriateness Criteria® on Chest Pain, Suggestive of Acute Coronary Syndrome

Acute chest pain suggestive of acute coronary syndrome is a frequent complaint in the emergency department. Acute coronary syndromes include myocardial infarction and unstable angina. Being able to establish the diagnosis rapidly and accurately may be lifesaving. A cardiac workup is indicated in this subset of patients in the acute setting, even if there are no ischemic changes on electrocardiography. If the clinical examination and initial cardiac workup suggest that a patient is having myocardial ischemia, the patient will usually be urgently referred for invasive coronary angiography and revascularization. In stable patients without evidence of ST elevation and ongoing myocardial ischemia, an initially conservative approach is sometimes considered. Cardiac risk stratification of this subgroup of patients who are at low and intermediate risk for coronary artery disease is recommended before discharge, and imaging is necessary to exclude ischemia as an etiology. Noninvasive cardiac imaging modalities include chest radiography, single photon-emission CT myocardial perfusion imaging, echocardiography, multidetector CT, PET, and MRI. Noncardiac etiologies of chest pain include aortic dissection, aortic aneurysm, pulmonary embolism, pericardial disease, and lung parenchymal disease. Noninvasive cardiac imaging in patients who are at low and intermediate risk for coronary artery disease may improve confidence regarding the safety of discharge from the emergency department. In addition to risk stratification, noncoronary etiologies for chest pain can be established with imaging.

Comparison of the quantitative first pass myocardial perfusion MRI with and without prospective slice tracking: Comparison between breath‐hold and free‐breathing condition

Physiologic motion of the heart is one of the major problems of myocardial blood flow quantification using first pass perfusion-MRI method. To overcome these problems, a perfusion pulse sequence with prospective slice tracking was developed. Cardiac motion was monitored by a navigator directly positioned at heart's basis to overcome no additional underlying model calculations connecting diaphragm and cardiac motion. Additional prescans were used before the perfusion measurement to detect slice displacements caused by remaining cardiac motion between navigator and the perfusion slice readout. The pulse sequence and subsequent quantification of myocardial blood flow was tested in healthy pigs with and without prospective slice tracking under both free-breathing and breath-hold conditions. To avoid influences by residual contrast agent concentration time courses were analyzed. Median myocardial blood flow values and interquartile ranges with prospective slice tracking under free-breathing and in a breath-hold were (1.04, interquartile range = 0.58 mL/min/g) and (1.20, interquartile range = 0.59 mL/min/g), respectively. This is in agreement with published positron emission tomography values. In measurements without prospective slice tracking (1.15, interquartile range = 1.58 mL/min/g), the interquartile range is significantly (P < 0.012) larger because of residual cardiac motion. In conclusion, prospective slice tracking reduces motion-induced variations of myocardial blood flow under both during breath-hold and under conditions of free-breathing.

First‐pass contrast‐enhanced myocardial perfusion MRI in mice on a 3‐T clinical MR scanner

First-pass contrast-enhanced myocardial perfusion MRI in rodents has so far not been possible due to the temporal and spatial resolution requirements. We developed a new first-pass perfusion MR method for rodent imaging on a clinical 3.0-T scanner (Philips Healthcare, Best, The Netherlands) that employed 10-fold k-space and time domain undersampling with constrained image reconstruction, using temporal basis sets (k-t principle component analysis) to achieve a spatial resolution of 0.2 × 0.2 × 1.5mm3 and an acquisition window of 43 msec. The method was successfully tested in five healthy and four infarcted mice (C57BL/6J) at heart rates of 495.1 ± 45.8 beats/min. Signal-intensity-time profiles showed a percentage myocardial signal increase of 141.3 ± 38.9% in normal mice, compared with 44.7 ± 32.4% in infarcted segments. Mean myocardial blood flow by Fermi function for constrained deconvolution in control mice was 7.3 ± 1.5 mL/g/min, comparable to published literature, with no significant differences between three myocardial segments. In infarcted segments, myocardial blood flow was significantly reduced to 1.2 ± 0.8 mL/g/min (P < 0.01). This is the first report of first-pass myocardial perfusion MR in a mouse model on a clinical 3-T MR scanner and using a k-t undersampling method. Data were acquired on a 3-T scanner, using an approach similar to clinical acquisition protocols, thus facilitating translation of imaging findings between rodent and human studies. Magn Reson Med, 2010. © 2010 Wiley-Liss, Inc.

Hypertension impairs myocardial blood perfusion reserve in subjects without regional myocardial ischemia

Quantitative analysis of myocardial perfusion MRI can provide noninvasive assessments of myocardial perfusion reserve (MPR), which is associated with endothelial function. Endothelial function is influenced by various factors, including hypertension, diabetes, dyslipidemia, renal dysfunction and anemia. The purpose of this study was to evaluate which risk factor is the strongest effector of MPR in subjects without regional myocardial ischemia. We studied 110 patients (66 years ±10, male 68%, hypertension 76%, diabetes mellitus (DM) 40% and dyslipidemia 65%) without regional myocardial ischemia. Adenosine triphosphate (ATP) stress and rest first-pass perfusion magnetic resonance (MR) images were acquired with a 1.5-T MR system, and MPR was calculated as the ratio of stress to rest myocardial blood flow (MBF). Average rest MBF in 110 patients was 1.07±0.62 ml min⁻¹ g⁻¹, whereas stress MBF was 3.15±1.93 ml min⁻¹ g⁻¹ and the MPR was 3.33±1.82. Rest MBF correlated significantly with hematocrit, whereas stress MBF showed a strong correlation with estimated glomerular filtration rate (e-GFR). MPR was associated with hypertension, age, e-GFR, hematocrit and left ventricular mass index (LVMI). In multiple regression analysis, hypertension (P=0.003, β=-0.274) showed the strongest correlation with MPR among other risk factors, such as diabetes (P=ns), dyslipidemia (P=ns), e-GFR (P=ns), LVMI (P=0.007, β=-0.248) and hematocrit (P=ns) after adjusting age and gender. Hypertension is the most important effector of MPR in subjects without myocardial ischemia.

Free‐breathing myocardial perfusion MRI using SW‐CG‐HYPR and motion correction

First-pass perfusion MRI is a promising technique to detect ischemic heart disease. Sliding window (SW) conjugate-gradient (CG) highly constrained back-projection reconstruction (HYPR) (SW-CG-HYPR) has been proposed to increase spatial coverage, spatial resolution, and SNR. However, this method is sensitive to respiratory motion and thus requires breath-hold. This work presents a non-model-based motion correction method combined with SW-CG-HYPR to perform free-breathing myocardial MR imaging. Simulation studies were first performed to show the effectiveness of the proposed motion correction method and its independence from the pattern of the respiratory motion. After that, in vivo studies were performed in six healthy volunteers. From all of the volunteer studies, the image quality score of free breathing perfusion images with motion correction (3.11 ± 0.34) is improved compared with that of images without motion correction (2.27 ± 0.32), and is comparable with that of successful breath-hold images (3.12 ± 0.38). This result was further validated by a quantitative sharpness analysis. The left ventricle and myocardium signal changes in motion corrected free-breathing perfusion images were closely correlated to those observed in breath-hold images. The correlation coefficient is 0.9764 for myocardial signals. Bland-Altman analysis confirmed the agreement between the free-breathing SW-CG-HYPR method with motion correction and the breath-hold SW-CG-HYPR. This technique may allow myocardial perfusion MRI during free breathing.

Systolic 3D first-pass myocardial perfusion MRI: Comparison with diastolic imaging in healthy subjects

Three-dimensional (3D) first-pass myocardial perfusion imaging (MPI) is a promising alternative to conventional two-dimensional multislice MPI due to its contiguous spatial coverage that is beneficial for estimating the size of perfusion defects. Data acquisition at mid-diastole is a typical choice for 3D MPI yet is sensitive to arrhythmia and variations in R-R interval that are common in cardiac patients. End systole is the second longest quiescent cardiac phase and is known to be less sensitive to the R-R variability. Therefore, 3D MPI with systolic acquisition may be advantageous in patients with severe arrhythmia once it is proven to be comparable to diastolic MPI in subjects with negligible R-R variation. In this work, we demonstrate the feasibility of 3D MPI with systolic data acquisition in five healthy subjects. We performed 3D MPI experiments in which 3D perfusion data were acquired at both end-systole and mid-diastole of every R-R interval and analyzed the similarity between resulting time intensity curves (TIC) from the two data sets. The correlation between systolic and diastolic TICs was extremely high (mean = 0.9841; standard deviation = 0.0166), and there was a significant linear correlation between the two time intensity curve upslopes and peak enhancements (P < 0.001).