Magnetic Resonance Myocardial Perfusion Imaging Research Articles

Fast Magnetic Resonance Myocardial Perfusion Imaging with Regadenoson: A Case Report and Review of the Literature

Fast Magnetic Resonance Myocardial Perfusion Imaging with Regadenoson: A Case Report and Review of the Literature

Automatic calculation of myocardial perfusion reserve using deep learning with uncertainty quantification.

Myocardial perfusion reserve index (MPRI) in magnetic resonance imaging (MRI) is an important indicator of ischemia, and its measurement typically involves manual procedures. The purposes of this study were to develop a fully automatic method for estimating the MPRI and to evaluate its performance. The method consisted of segmenting the myocardium in dynamic contrast-enhanced (DCE) myocardial perfusion MRI data using Monte Carlo dropout U-Net, dividing the myocardium into segments based on landmark localization with machine learning, and estimating the MPRI after the calculation of the left ventricular and myocardial contrast upslopes. The proposed method was compared with a reference method, which involved manual adjustments of the myocardial contours and upslope ranges. In test subjects, MPRIs measured by the proposed technique correlated with those by the manual reference in segmental assessment [intraclass correlation coefficient (ICC) =0.75, 95% CI: 0.70-0.79, P<0.001]. The automatic and reference MPRI values showed a mean difference of -0.02 and 95% limits of agreement of (-0.86, 0.82). The proposed automatic method is based on deep learning segmentation and machine learning landmark detection for MPRI measurements in DCE perfusion MRI. It holds the potential to efficiently and quantitatively assess myocardial ischemia without any user's interaction.

Fully automated pixel-wise quantitative CMR-myocardial perfusion with CMR-coronary angiography to detect hemodynamically significant coronary artery disease.

We applied a fully automated pixel-wise post-processing framework to evaluate fully quantitative cardiovascular magnetic resonance myocardial perfusion imaging (CMR-MPI). In addition, we aimed to evaluate the additive value of coronary magnetic resonance angiography (CMRA) to the diagnostic performance of fully automated pixel-wise quantitative CMR-MPI for detecting hemodynamically significant coronary artery disease (CAD). A total of 109 patients with suspected CAD were prospectively enrolled and underwent stress and rest CMR-MPI, CMRA, invasive coronary angiography (ICA), and fractional flow reserve (FFR). CMRA was acquired between stress and rest CMR-MPI acquisition, without any additional contrast agent. Finally, CMR-MPI quantification was analyzed by a fully automated pixel-wise post-processing framework. Of the 109 patients, 42 patients had hemodynamically significant CAD (FFR ≤ 0.80 or luminal stenosis ≥ 90% on ICA) and 67 patients had hemodynamically non-significant CAD (FFR ˃ 0.80 or luminal stenosis < 30% on ICA) were enrolled. On the per-territory analysis, patients with hemodynamically significant CAD had higher myocardial blood flow (MBF) at rest, lower MBF under stress, and lower myocardial perfusion reserve (MPR) than patients with hemodynamically non-significant CAD (p < 0.001). The area under the receiver operating characteristic curve of MPR (0.93) was significantly larger than those of stress and rest MBF, visual assessment of CMR-MPI, and CMRA (p < 0.05), but similar to that of the integration of CMR-MPI with CMRA (0.90). Fully automated pixel-wise quantitative CMR-MPI can accurately detect hemodynamically significant CAD, but the integration of CMRA obtained between stress and rest CMR-MPI acquisition did not provide significantly additive value. • Full quantification of stress and rest cardiovascular magnetic resonance myocardial perfusion imaging can be postprocessed fully automatically, generating pixel-wise myocardial blood flow (MBF) and myocardial perfusion reserve (MPR) maps. • Fully quantitative MPR provided higher diagnostic performance for detecting hemodynamically significant coronary artery disease, compared with stress and rest MBF, qualitative assessment, and coronary magnetic resonance angiography (CMRA). • The integration of CMRA and MPR did not significantly improve the diagnostic performance of MPR alone.

Evaluation of coronary microvascular dysfunction and risk factors in children and youth with Turner syndrome by magnetic resonance myocardial perfusion imaging.

Turner syndrome (TS) has an increased predisposition to ischaemic heart disease and the status of coronary microcirculation in TS is largely unknown. This study aims to evaluate myocardial microvascular function in TS using first-pass magnetic resonance perfusion imaging and determine significant risk factors contributing to microvascular dysfunction in the early stage. Perspective cohort study. The study cohort consisted of 67 children and youth with TS and 32 age- and gender-matched controls. Measurements Clinical characteristics, left ventricle (LV) volume and functionand cardiovascular magnetic resonance-derived myocardial perfusion parameters were assessed. Univariable and multivariable linear regression analyses were performed to assess the potential risk factors for microvascular dysfunction. Microvascular perfusion decreased in TS in global and segmented myocardium as reflected in the lower upslopecor and maximum signal intensity (MaxSI) of LV myocardium compared to controls. Multivariable linear regression analysis indicated that age (β = -0.107, 95% confidence interval [CI] = -0.201 to -0.013, p = .026) and being overweight/obese (β = -1.155, CI = -2.134 to -0.176, p = .021) were independent impact factors of microvascular dysfunction. Subgroup analysis showed the upslopecor of older patients with TS decreased more significantly compared with that of normal controls. Upslopecor and MaxSI were lower in overweight/obese patients with TS than in patients with normal body mass index (BMI) and controls. Myocardial microvascular dysfunction can occur in children and youth patients with TS. Age and overweight/obesity were the independent risk factors of microvascular dysfunction, which imply the importance of lowering BMI for the prevention of coronary heart disease in young TS population.

Value of myocardial deformation parameters for detecting significant coronary artery disease.

Introduction: The study aimed to evaluate the diagnostic value of global and regional myocardial deformation parameters derived from two-dimensional speckle-tracking echocardiography to detect functionally significant coronary artery stenosis. Methods: Dobutamine stress echocardiography and cardiac magnetic resonance myocardial perfusion imaging (CMR-MPI) were performed on 145 patients with a moderate and high probability of coronary artery disease (CAD) and LVEF≥55%. Significant CAD was defined as>50% stenosis of the left main stem,>70% stenosis in a major coronary vessel, or in the presence of intermediate stenosis (50-69%) validated as hemodynamically significant by CMRMPI. Patients were divided in two groups: non-pathological (48.3%) vs pathological (51.7%), according to CAG and CMR-MPI results. Afterwards, off-line speckle-tracking analysis was performed to analyse myocardial deformation parameters. Results: There were no differences in myocardial deformation parameters at rest between groups, except global longitudinal strain (GLS) and global radial strain (GRS) were significantly lower in the CAD (+) group: -21.3±2.2 vs.-16.3±2.3 (P<0.001) and 39.7±23.2 vs. 24.5±15.8 (P<0.001). GLS and regional longitudinal strain rate (SR) had the highest diagnostic value at high dobutamine dose with AUC of 0.902 and 0.878, respectively. At early recovery, GLS was also found to be the best myocardial deformation parameter with a sensitivity of 78%, specificity 67%, AUC 0.824. Conclusion: Global and regional myocardial deformation parameters are highly sensitive and specific in detecting functionally significant CAD. The combination of deformation parameters and WMA provides an incremental diagnostic value for patients with a moderate and high probability of CAD, especially the combination with regional longitudinal SR.

Safety and Efficacy of Regadenoson for Pediatric Stress Perfusion Cardiac MRI with Quantification of Myocardial Blood Flow.

Myocardial stress perfusion magnetic resonance imaging is a non-invasive tool to assess for myocardial ischemia and viability. Pediatric myocardial stress perfusion MRI can be challenging due to multiple intravenous lines, sedation, inadequate breath holding, fast heart rates, and complex anatomy. We performed a retrospective analysis in 39 children to evaluate safety and efficacy of regadenoson, a coronary vasodilator administered via a single intravenous line (6–10 mcg/kg), with respiratory motion correction (MOCO) and semi-quantitative blood flow analysis. Stress response data and adverse events were recorded, and image quality compared between native and MOCO reconstructions, assessing for perfusion deficits. Semi-quantitative analysis compared myocardial perfusion reserve index (MPRI) between patients who had a focal perfusion defect, patients who had undergone an orthotopic heart transplant, and non-transplant patients with no focal defects. Stress perfusion was completed in 38/39 patients (median age 15 years with a 41 ± 27% rise in heart rate (p < 0.005). Fifteen out of thirty-eight had transient minor side effects with no major adverse events. MOCO image quality was better than non-MOCO (4.63 vs. 4.01 at rest, p < 0.005: 4.41 vs. 3.84 at stress, p < 0.005). Reversible perfusion defects were seen in 4/38 patients with lower segmental mean MPRI in the area of the perfusion defect, nearing statistical significance when compared to non-transplant patients with no defects (0.78 ± 0.22 vs. 0.99 ± 0.36, p = 0.07). The global MPRI of the 16 patients who had undergone orthotopic heart transplant was significantly lower than the non-transplant patients (0.75 ± 0.22 vs. 0.92 ± 0.23, p = 0.03). Regadenoson is a safe and effective coronary vasodilator for pediatric stress perfusion MRI with MOCO producing better image quality and allowing for semi-quantitative assessment of perfusion deficits that correlate with qualitative assessment.

Splenic T1-Mapping for Predicting Adenosine Stress Adequacy in Cardiac Magnetic Resonance Myocardial Perfusion Imaging: A Validation and Reproducibility Study

Splenic T1-Mapping for Predicting Adenosine Stress Adequacy in Cardiac Magnetic Resonance Myocardial Perfusion Imaging: A Validation and Reproducibility Study

Deep Learning-Based Segmentation and Uncertainty Assessment for Automated Analysis of Myocardial Perfusion MRI Datasets Using Patch-Level Training and Advanced Data Augmentation.

In this work, we develop a patch-level training approach and a task-driven intensity-based augmentation method for deep-learning-based segmentation of motion-corrected perfusion cardiac magnetic resonance imaging (MRI) datasets. Further, the proposed method generates an image-based uncertainty map thanks to a novel spatial sliding-window approach used during patch-level training, hence allowing for uncertainty quantification. Using the quantified uncertainty, we detect the out-of-distribution test data instances so that the end-user can be alerted that the test data is not suitable for the trained network. This feature has the potential to enable a more reliable integration of the proposed deep learning-based framework into clinical practice. We test our approach on external MRI data acquired using a different acquisition protocol to demonstrate the robustness of our performance to variations in pulse-sequence parameters. The presented results further demonstrate that our deep-learning image segmentation approach trained with the proposed data-augmentation technique incorporating spatiotemporal (2D+time) patches is superior to the state-of-the-art 2D approach in terms of generalization performance.

Stress cardiac MRI for the evaluation of CCS patients in a real-world tertiary care center

Abstract Background The MR INFORM trial demonstrated that myocardial perfusion Magnetic Resonance Imaging (MRI) is non-inferior to Invasive Coronary Angiography (ICA) with measurement of Fractional Flow Reserve (FFR) in guiding the management of patients with stable coronary artery disease with respect to major adverse cardiac events, despite a reduced rate of revascularized patients. We sought to evaluate if a MRI-based strategy performed well also in patients with Chronic Coronary Syndrome (CCS) with intermediate coronary plaques observed by Coronary Computed Tomography Angiography (CCTA). Methods At our tertiary care center, patients with suspicion of CCS at intermediate risk first underwent CCTA. Subsequently, those showing intermediate coronary plaques underwent dipyridamole stress cardiac MRI. Revascularization was recommended for patients showing ischemia in at least two consecutive left ventricular segments or 6% of the myocardium. ICA and instantaneous FFR was performed in all of these patients, in order to confirm the indication for revascularization. The endpoint was a composite of death, non-fatal myocardial infarction, and target-vessel revascularization within 1 year. Results 55 patients at intermediate risk underwent CCTA. 15 patients with no or only minimal plaques (stenosis &amp;lt;30%) and those with obstructive plaques (stenosis &amp;gt;70%) were excluded. 40 patients showed intermediate plaques (30–70% stenosis): 102 plaques total were classified as: non calcified n=9 (9%), calcified n=48 (47%), and mixed n=45 (44%). These patients underwent stress MRI, on the basis of which n=12 (30%) patients met criteria to recommend revascularization, whereas n=28 (70%) did not. The indication for revascularization was confirmed by ICA plus iFFR in 10 patients, and excluded in 2 (sensitivity = 100%, 95% CI 69%-100%; specificity = 93%, 95% CI 78%-99%; NPV = 100%, 95% CI 88%-100%; PPV = 83%, 95% CI 57%-95%; accuracy = 95%, 95% CI 83%-99%). Revascularization was obtained through PCI in 9 patients and through CABG in the remaining patient. All patients, regardless of revascularization, received optimal medical therapy (OMT), including high-dose statins. Throughout a 1-year follow-up, the composite endpoint occurred in only 1 patient belonging to the revascularized group, who was admitted to our hospital for NSTEMI. No adverse events were observed among the negative-MRI patients and the positive-MRI not-revascularized patients. All patients remained free from angina. Conclusions According to current European guidelines, in our tertiary care center patients with CCS at intermediate risk first underwent CCTA. A stress MRI-based strategy for the evaluation of intermediate plaques led us to refine the selection of patients needing coronary revascularization. No events occurred in patients with negative MRI, highlighting the accuracy of CCTA plus stress MRI strategy in these patients. In all patients, OMT may have contributed to freedom from angina. Funding Acknowledgement Type of funding sources: None.

Direct Comparison of Bayesian and Fermi Deconvolution Approaches for Myocardial Blood Flow Quantification: In silico and Clinical Validations.

Cardiac magnetic resonance myocardial perfusion imaging can detect coronary artery disease and is an alternative to single-photon emission computed tomography or positron emission tomography. However, the complex, non-linear MR signal and the lack of robust quantification of myocardial blood flow have hindered its widespread clinical application thus far. Recently, a new Bayesian approach was developed for brain imaging and evaluation of perfusion indexes (Kudo et al., 2014). In addition to providing accurate perfusion measurements, this probabilistic approach appears more robust than previous approaches, particularly due to its insensitivity to bolus arrival delays. We assessed the performance of this approach against a well-known and commonly deployed model-independent method based on the Fermi function for cardiac magnetic resonance myocardial perfusion imaging. The methods were first evaluated for accuracy and precision using a digital phantom to test them against the ground truth; next, they were applied in a group of coronary artery disease patients. The Bayesian method can be considered an appropriate model-independent method with which to estimate myocardial blood flow and delays. The digital phantom comprised a set of synthetic time-concentration curve combinations generated with a 2-compartment exchange model and a realistic combination of perfusion indexes, arterial input dynamics, noise and delays collected from the clinical dataset. The myocardial blood flow values estimated with the two methods showed an excellent correlation coefficient (r2 > 0.9) under all noise and delay conditions. The Bayesian approach showed excellent robustness to bolus arrival delays, with a similar performance to Fermi modeling when delays were considered. Delays were better estimated with the Bayesian approach than with Fermi modeling. An in vivo analysis of coronary artery disease patients revealed that the Bayesian approach had an excellent ability to distinguish between abnormal and normal myocardium. The Bayesian approach was able to discriminate not only flows but also delays with increased sensitivity by offering a clearly enlarged range of distribution for the physiologic parameters.

Therapeutic effects of coronary granulocyte colony-stimulating factor on rats with chronic ischemic heart disease.

BackgroundThe aim of this study was to evaluate the therapeutic effects of coronary granulocyte colony-stimulating factor (G-CSF) on rats with chronic ischemic heart disease (CIHD).MethodsThirty healthy rats were randomly divided into control, subcutaneous and intracoronary G-CSF injection groups (n = 10) after the CIHD model was established. Left ventricular ejection fraction (LVEF), myocardial injury area, myocardial perfusion area and viable myocardium were observed by coronary angiography, dual-isotopic myocardial imaging and first-pass delayed myocardial perfusion magnetic resonance imaging (MRI) before modeling as well as 2 and 4 weeks after surgery.ResultsThe peak times of peripheral blood and subcutaneous G-CSF levels were 3 and 5 days after mobilization, respectively. The peripheral blood CD34+/CD133+ cell ratio of subcutaneous or intracoronary G-CSF injection group significantly exceeded that of the control group (P < 0.05). The distal stenosis degrees of target lesions in subcutaneous and intracoronary G-CSF injection groups were significantly lower than that of the control group (P < 0.05). Compared with the situation before mobilization, LVEF was significantly improved after 2 weeks in intracoronary and subcutaneous G-CSF injection groups (P < 0.01). Their infarcted myocardial areas were reduced, the left ventricular remodeling was relieved, the percentage of viable myocardium was increased, angiogenesis was promoted and cardiomyocyte apoptosis was inhibited.ConclusionIntracoronary G-CSF injection is safe and effective as subcutaneous injection, improving the cardiac function of CIHD rats.

Improvement of image quality on low-dose dynamic myocardial perfusion computed tomography with a novel 4-dimensional similarity filter.

The aim of this study was to evaluate the effect of a novel 4-dimensional similarity filter (4DSF) on quantitative and qualitative parameters of low-dose dynamic myocardial computed tomography perfusion (CTP) images.In this retrospective study, medical records of 32 patients with suspected or known coronary artery disease who underwent dynamic myocardial CTP at 80 kV were included. The 4DSF reduces noise by averaging voxels that have similar dynamic behavior after adaptive iterative dose reduction 3D (AIDR3D) and deformable image registration were applied. Qualitative (artefact, contour sharpness, and myocardial homogeneity [1 = poor; 2 = intermediate; 3 = good]) and quantitative measurement (standard deviation [SD] and signal-to-noise ratio [SNR]) were compared between the 4DSF and AIDR3D. Contrast-to-noise ratio (CNR) between ischemic and normal remote myocardium was also assessed using myocardial perfusion magnetic resonance imaging as the reference standard in seven patients.The 4DSF was successfully applied to all the images. Improvement in subjective image quality yielded by 4DSF was higher than that yielded by AIDR3D (homogeneity, 1.0 [3 vs 2]; artefact, 1.5 [3 vs 1.5]; P < .001) in all patients. The 4DSF significantly decreased the SD by 59% (AIDR3D vs 4DSF: 33.5 ± 0.4 vs 13.8 ± 0.4, P < .001), increased the SNR by 134% (AIDR3D vs 4DSF: 4.4 ± 0.2 vs 10.3 ± 0.2, P < .001), and increased the CNR by 131% (AIDR3D vs 4DSF: 1.6 ± 0.2 vs 3.7 ± 0.2, P < .001).The 4DSF improved the qualitative and quantitative parameters of low-dose dynamic myocardial CTP images.

Safety of regadenoson with theophylline reversal during dynamic computed tomography perfusion and magnetic resonance imaging in patients with coronary artery disease.

The use of regadenoson in dynamic computed tomography perfusion (CTP) and magnetic resonance myocardial perfusion imaging (MR MPI) is off‑label. The study aimed to assess the safety of regadenoson with theophylline reversal during CTP and MR MPI in patients with coronary artery disease (CAD). In this prospective study, patients with 1 or more intermediate coronary artery stenoses on computed tomography angiography underwent CTP and MR MPI with 0.4 mg of regadenoson. After examinations, 200 mg of theophylline was given intravenously in 100 ml of saline. Changes in blood pressure (BP) and heart rate (HR) were repeatedly assessed. All side effects and adverse events were recorded. Out of 106 examinations in 53 patients (25 females, 63.5 [8.5] years), all were diagnostic. There were no deaths, myocardial infarctions, severe arrhythmias, high‑grade atrioventricular blocks, or bronchospasms. The most common symptoms were palpitations (17%), hot flushing (8%), chest discomfort (4%), and mild dyspnea (3%). There were no differences between baseline and peak BP. There was an increase in median (interquartile range) peak HR after regadenoson as compared with baseline (MR MPI, 63 [59-75] bpm vs 93 [86-102] bpm; P <0.001; and CTP, 65 [60-70] bpm vs 95 [86-107] bpm; P <0.001). The hemodynamic response to regadenoson and its side effects were completely reversible by theophylline. Regadenoson may be a safe vasodilator for CTP and MR MPI in patients with CAD. The administration of theophylline after perfusion is safe and reverses side effects of regadenoson.

Regadenoson dynamic computed tomography myocardial perfusion using low-dose protocol for evaluation of the ischemic burden. ULYSSES study

BackgroundThe purpose of this study was to assess the feasibility of low-dose dynamic regadenoson computed tomography perfusion (CTP) protocol, and to determine which parameters provide the best diagnostic yield for the presence and burden of ischemia in reference to the magnetic resonance myocardial perfusion imaging (MR MPI). MethodsFifty six patients with ≥1 intermediate (50–90%) coronary artery stenosis on CTA underwent dynamic stress CTP and MR MPI. The distribution of contrast agent in CTP was represented for each myocardial segment as either absolute or indexed: myocardial blood flow (MBF), myocardial blood volume (MBV), perfused capillary blood volume (PCBV), peak value (PV), time to peak (TTP), respectively. ResultsOf 56 patients (25 females, 63.5 ± 8.5y), 15 (27%) were diagnosed with reversible ischemia and 3 (5%) with fixed ischemia on the MR MPI. The median radiation dose for dynamic CTP scan was 352.00 [276.4–496.6] mGy*cm. The optimal cut-off point for the prediction of reversible ischemia on MR MPI for the absolute parameters were: MBF ≤156.49 (AUC=0.899), MBV ≤15.06 (AUC=0.901), PCBV ≤7.90 (AUC=0.880), PV ≤ 88.30 (AUC=0.766), TTP ≥22.58 (AUC=0.595); and for the indexed: indexed MBF ≤0.78 (AUC=0.926), indexed MBV ≤0.81 (AUC=0.924), indexed PCBV ≤0.70 (AUC=0.894); indexed PV ≤ 0.79 (AUC=0.869), indexed TTP ≤0.87 (AUC=0.685). The best parameters for ischemia detection were indexed MBF and indexed MBV, with sensitivities 91% and 89%, specificities 97% and 96%, NPV 99% and 99%, PPV 76% and 69%, and accuracies 96% and 95%, respectively. In per patient analysis, indexed MBF correlated significantly better with the ischemia burden than any of the absolute parameters (p < 0.01 for all comparisons). ConclusionsRegadenoson dynamic CTP using low-dose protocol is feasible while maintaining high diagnostic accuracy. The best diagnostic value may be provided by indexed parameters, of which indexed MBF and indexed MBV may provide best incremental value in identification of the presence and burden of ischemia.

Perceived Dark Rim Artifact in First-Pass Myocardial Perfusion Magnetic Resonance Imaging Due to Visual Illusion.

To demonstrate that human visual illusion can contribute to sub-endocardial dark rim artifact in contrast-enhanced myocardial perfusion magnetic resonance images. Numerical phantoms were generated to simulate the first-passage of contrast agent in the heart, and rendered in conventional gray scale as well as in color scale with reduced luminance variation. Cardiac perfusion images were acquired from two healthy volunteers, and were displayed by the same gray and color scales used in the numerical study. Before and after k-space windowing, the left ventricle (LV)-myocardium boarders were analyzed visually and quantitatively through intensity profiles perpendicular the boarders. k-space windowing yielded monotonically decreasing signal intensity near the LV-myocardium boarder in the phantom images, as confirmed by negative finite difference values near the board ranging -1.07 to -0.14. However, the dark band still appears, which is perceived by visual illusion. Dark rim is perceived in the in-vivo images after k-space windowing that removed the quantitative signal dip, suggesting that the perceived dark rim is a visual illusion. The perceived dark rim is stronger at peak LV enhancement than the peak myocardial enhancement, due to the larger intensity difference between LV and myocardium. In both numerical phantom and in-vivo images, the illusory dark band is not visible in the color map due to reduced luminance variation. Visual illusion is another potential cause of dark rim artifact in contrast-enhanced myocardial perfusion MRI as demonstrated by illusory rim perceived in the absence of quantitative intensity undershoot.

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.

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

Diffuse myocardial fibrosis in adolescents operated with arterial switch for transposition of the great arteries - A CMR study

Whole Left Ventricular Coverage Versus Conventional 3-Slice Myocardial Perfusion Magnetic Resonance Imaging for the Detection of Suspected Coronary Artery Disease

Sliding-window conjugate-gradient highly constrained back-projection reconstruction (SW-CG-HYPR) allows whole left ventricular coverage, improved temporal and spatial resolution, and signal-to-noise ratio compared to the conventional 3-slice saturation recovery turbo-fast low-angle shot (SR-Turbo-FLASH) sequence. We prospectively compared the diagnostic value of whole leftventricular coverage myocardial perfusion magnetic resonance imaging (MRI) and conventional 3-slice technique in patients with suspected coronary artery disease (CAD). Thirty consecutive patients with suspected CAD who were scheduled for coronary angiography underwent myocardial perfusion MRI with both SW-CG-HYPR and SR-Turbo-FLASH in random order at 3.0 T. Perfusion defects were interpreted visually by two blinded observers and were correlated to x-ray angiographic stenoses ≥50%. Receiver-operating characteristic curve analysis was used to compare the diagnostic performance of the two imaging techniques. The image quality score of SW-CG-HYPR was significantly higher than that of SR-Turbo-FLASH (3.4 ± 0.6 vs 3.0 ± 0.7, respectively; p < 0.05). In the per-patient analysis, SW-CG-HYPR provided a higher sensitivity (94% vs 89%), specificity (83% vs 75%), and diagnostic accuracy (90% vs 83%) for the detection of CAD than SR-Turbo-FLASH. In the per-vessel analysis, the diagnostic performance of SW-CG-HYPR was significantly greater than that of SR-Turbo-FLASH for the overall detection of CAD (area under receiver-operating characteristic curve: 0.96 ± 0.02 vs 0.90 ± 0.03, respectively; p < 0.05). Whole left ventricular coverage myocardial perfusion MRI has higher diagnostic accuracy compared to conventional 3-slice technique for the detection of suspected CAD.

Simultaneous multi slice (SMS) balanced steady state free precession first-pass myocardial perfusion cardiovascular magnetic resonance with iterative reconstruction at 1.5\xa0T

BackgroundSimultaneous-Multi-Slice (SMS) perfusion imaging has the potential to acquire multiple slices, increasing myocardial coverage without sacrificing in-plane spatial resolution. To maximise signal-to-noise ratio (SNR), SMS can be combined with a balanced steady state free precession (bSSFP) readout. Furthermore, application of gradient-controlled local Larmor adjustment (GC-LOLA) can ensure robustness against off-resonance artifacts and SNR loss can be mitigated by applying iterative reconstruction with spatial and temporal regularisation. The objective of this study was to compare cardiovascular magnetic resonance (CMR) myocardial perfusion imaging using SMS bSSFP imaging with GC-LOLA and iterative reconstruction to 3 slice bSSFP.MethodsTwo contrast-enhanced rest perfusion sequences were acquired in random order in 8 patients: 6-slice SMS bSSFP and 3 slice bSSFP. All images were reconstructed with TGRAPPA. SMS images were also reconstructed using a non-linear iterative reconstruction with L1 regularisation in wavelet space (SMS-iter) with 7 different combinations for spatial (λσ) and temporal (λτ) regularisation parameters. Qualitative ratings of overall image quality (0 = poor image quality, 1 = major artifact, 2 = minor artifact, 3 = excellent), perceived SNR (0 = poor SNR, 1 = major noise, 2 = minor noise, 3 = high SNR), frequency of sequence related artifacts and patient related artifacts were undertaken. Quantitative analysis of contrast ratio (CR) and percentage of dark rim artifact (DRA) was performed.ResultsAmong all SMS-iter reconstructions, SMS-iter 6 (λσ 0.001 λτ 0.005) was identified as the optimal reconstruction with the highest overall image quality, least sequence related artifact and higher perceived SNR. SMS-iter 6 had superior overall image quality (2.50 ± 0.53 vs 1.50 ± 0.53, p = 0.005) and perceived SNR (2.25 ± 0.46 vs 0.75 ± 0.46, p = 0.010) compared to 3 slice bSSFP. There were no significant differences in sequence related artifact, CR (3.62 ± 0.39 vs 3.66 ± 0.65, p = 0.88) or percentage of DRA (5.25 ± 6.56 vs 4.25 ± 4.30, p = 0.64) with SMS-iter 6 compared to 3 slice bSSFP.ConclusionsSMS bSSFP with GC-LOLA and iterative reconstruction improved image quality compared to a 3 slice bSSFP with doubled spatial coverage and preserved in-plane spatial resolution. Future evaluation in patients with coronary artery disease is warranted.

Diagnostic performance of static single-scan stress perfusion cardiac computed tomography in detecting hemodynamically significant coronary artery stenosis: a comparison with combined invasive coronary angiography and cardiovascular magnetic resonance-myocardial perfusion imaging.

Background Non-invasive anatomical and physiological evaluations of coronary artery disease (CAD) may be obtained with static single-scan stress perfusion cardiac computed tomography (SSPCT). Purpose To determine the diagnostic performance of static SSPCT for identifying hemodynamically significant CAD. Material and Methods This prospective study included 29 patients with suspected or known CAD who underwent static SSPCT, cardiovascular magnetic resonance myocardial perfusion imaging (CMR-MPI), and invasive coronary angiography (ICA). CT was performed as follows: (i) coronary calcium scan; (ii) static SSPCT for both coronary artery (coronary CT angiography [CCTA]) and myocardial perfusion (perfusion CT [PCT]) during adenosine infusion; (iii) late-phase scan. The diagnostic performance of CCTA alone, PCT alone, and SSPCT for the detection of a hemodynamically significant CAD (a perfusion defect in a vascular territory subtended by a coronary vessel with ≥ 50% stenosis) was compared with that of combined ICA/CMR-MPI representing the standard of reference. Results Twenty-three (79%) patients and 47 (54%) vascular territories manifested ischemia-causing coronary stenoses by combined ICA/CMR-MPI. The per-vessel sensitivity, specificity, positive and negative predictive values, and area under the receiver operating characteristic curve (AUC) of the SSPCT were 92%, 88%, 90%, 90%, and 0.90, respectively, compared to those of the combined ICA/CMR-MPI. These values for the CCTA alone were 96%, 63%, 75%, 93%, and 0.79, respectively; and the values for the PCT alone were 94%, 83%, 86%, 92%, and 0.88, respectively. The AUC of SSPCT was significantly ( P = 0.013) higher than that of the CCTA alone. Conclusion Static SSPCT may facilitate detection of hemodynamically significant CAD.