First-pass Perfusion Research Articles

Additional diagnostic value of first-pass myocardial perfusion imaging without stress when combined with 64-row detector coronary CT angiography in patients with coronary artery disease

ObjectiveMulti-detector coronary CT angiography (CCTA) can detect coronary stenosis, but it has a limited ability to evaluate myocardial perfusion. We evaluated the usefulness of first-pass CT-myocardial perfusion imaging (MPI) in...

Accelerated dual-contrast first-pass perfusion MRI of the mouse heart: development and application to diet-induced obese mice.

Gene-modified mice may be used to elucidate molecular mechanisms underlying abnormal myocardial blow flow (MBF). We sought to develop a quantitative myocardial perfusion imaging technique for mice and to test the hypothesis that myocardial perfusion reserve (MPR) is reduced in a mouse model of diet-induced obesity (DIO). A dual-contrast saturation-recovery sequence with ky -t undersampling and a motion-compensated compressed sensing reconstruction algorithm was developed for first-pass MRI on a small-bore 7 Tesla system. Control mice were imaged at rest and with the vasodilators ATL313 and Regadenoson (n = 6 each). In addition, we imaged mice fed a high-fat diet (HFD) for 24 weeks. In control mice, MBF was 5.7 ± 0.8 mL/g/min at rest and it increased to 11.8 ± 0.6 mL/g/min with ATL313 and to 10.4 ± 0.3 mL/g/min with Regadenoson. In HFD mice, we detected normal resting MBF (5.6 ± 0.4 versus 5.0 ± 0.3 on control diet), low MBF at stress (7.7 ± 0.4 versus 10.4 ± 0.3 on control diet, P < 0.05), and reduced MPR (1.4 ± 0.2 versus 2.0 ± 0.3 on control diet, P < 0.05). Accelerated dual-contrast first-pass MRI with motion-compensated compressed sensing provides spatiotemporal resolution suitable for measuring MBF in free-breathing mice, and detected reduced MPR in DIO mice. These techniques may be used to study molecular mechanisms that underlie abnormal myocardial perfusion.

Optimized saturation pulse train for human first-pass myocardial perfusion imaging at 7T.

PurposeTo investigate whether saturation using existing methods developed for 3T imaging is feasible for clinical perfusion imaging at 7T, and to propose a new design of saturation pulse train for first-pass myocardial perfusion imaging at 7T.MethodsThe new design of saturation pulse train consists of four hyperbolic-secant (HS8) radiofrequency pulses, whose peak amplitudes are optimized for a target range of static and transmit field variations and radiofrequency power deposition restrictions measured in the myocardium at 7T. The proposed method and existing methods were compared in simulation, phantom, and in vivo experiments.ResultsIn healthy volunteer experiments without contrast agent, average saturation efficiency with the proposed method was 97.8%. This is superior to results from the three previously published methods at 86/95/90.8%. The first series of human first-pass myocardial perfusion images at 7T have been successfully acquired with the proposed method.ConclusionExisting saturation methods developed for 3T imaging are not optimal for perfusion imaging at 7T. The proposed new design of saturation pulse train can saturate effectively, and with this method first-pass myocardial perfusion imaging is feasible in humans at 7T. Magn Reson Med 73:1450–1456, 2015. © 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance.

Magnetic Resonance Imaging Detects Changes in Structure and Perfusion, and Response to Therapy in Early Cystic Fibrosis Lung Disease

Studies demonstrating early structural lung damage in infants and preschool children with cystic fibrosis (CF) suggest that noninvasive monitoring will be important to identify patients who may benefit from early therapeutic intervention. Previous studies demonstrated that magnetic resonance imaging (MRI) detects structural and functional abnormalities in lungs from older patients with CF without radiation exposure. To evaluate the potential of MRI to detect abnormal lung structure and perfusion in infants and preschool children with CF, and to monitor the response to therapy for pulmonary exacerbation. MRI studies were performed in 50 children with CF (age, 3.1 ± 2.1 yr; range, 0-6 yr) in stable clinical condition (n = 40) or pulmonary exacerbation before and after antibiotic treatment (n = 10), and in 26 non-CF control subjects (age, 2.9 ± 1.9 yr). T1- and T2-weighted sequences before and after intravenous contrast and first-pass perfusion imaging were acquired, and assessed on the basis of a dedicated morphofunctional score. MRI demonstrated bronchial wall thickening/bronchiectasis, mucus plugging, and perfusion deficits from the first year of life in most stable patients with CF (global score, 10.0 ± 4.0), but not in non-CF control subjects (score, 0.0 ± 0.0; P < 0.001). In patients with exacerbations, the global MRI score was increased to 18.0 ± 2.0 (P < 0.001), and was significantly reduced to 12.0 ± 3.0 (P < 0.05) after antibiotic therapy. MRI detected abnormalities in lung structure and perfusion, and response to therapy for exacerbations in infants and preschool children with CF. These results support the development of MRI for noninvasive monitoring and as an end point in interventional trials for early CF lung disease. Clinical trial registered with www.clinicaltrials.gov (NCT00760071).

Comprehensive Dobutamine Stress CMR Versus Echocardiography in LBBB and Suspected Coronary Artery Disease

This study aimed to compare dobutamine stress cardiac magnetic resonance (DSCMR) withdobutamine stress echocardiography (DSE) in patients with left bundle branch block (LBBB) and suspected coronary artery disease (CAD). Noninvasive diagnosis of CAD in patients with pre-existent LBBB is difficult because single-photon emission computed tomography and stress echocardiography both have limitations. We hypothesized that a comprehensive DSCMR examination including cine, perfusion, and late gadolinium enhancement imaging would be more accurate than DSE, thus potentially reducing the number of unnecessary invasive coronary angiograms. We prospectively evaluated 82 consecutive patients with LBBB referred to our cardiology clinic for investigation of suspected CAD. All 82 patients underwent DSE, DSCMR, and invasive quantitative coronary angiography within 14 days. We compared the diagnostic accuracy of DSE, CMR cine imaging, the additive value of first-pass perfusion, and late gadolinium enhancement. In the comprehensive examination, a positive result was adjudged as the presence of either subendocardial or transmural late gadolinium enhancement with or without inducible peri-infarct ischemia or an inducible perfusion defect corresponding to an inducible regional wall motion abnormality. CMR cine imaging (regional wall motion abnormalities) had higher specificity, negative predictive value, and overall diagnostic accuracy than did DSE (87.5% vs. 72.9%; 80.8% vs. 67.3%; and 80.4% vs. 72.0%, respectively), although sensitivity was the same (72.0%). The addition of first-pass stress perfusion and late gadolinium enhancement (scar) further improved diagnostic confidence (sensitivity 82.4%, specificity 95.8%, positive predictive value 93.3%, negative predictive value 88.5%, and diagnostic accuracy 90.2%). DSCMR is a safe procedure and has greater diagnostic accuracy than does DSE in assessing patients with suspected CAD and LBBB. A comprehensive examination with the addition of perfusion and late gadolinium enhancement to CMR cine imaging significantly boosted specificity and sensitivity, making DSCMR a reliable alternative to invasive quantitative coronary angiography in this group of patients.

Severe mitral stenosis as the first manifestation of systemic lupus erythematosus in a 20-year-old woman: the value of magnetic resonance imaging in the diagnosis of Libman-Sacks endocarditis

We report a case of severe mitral stenosis caused by Libman-Sacks endocarditis, as an initial manifestation of systemic lupus erythematosus (SLE) in a 20-year-old woman. Cardiac magnetic resonance imaging (MRI) demonstrated a thickening of the mitral valve with basal endocardial thickening exhibiting defect on first-pass perfusion short-axis acquisition and delayed enhancement in keeping with extensive fibrous endocarditis. The patient underwent successful mechanical mitral valve replacement. This case illustrates that MRI is useful in diagnosing this recognised but uncommon cardiac complication of SLE and excluding differential diagnosis such as valve tumour and infective endocarditis with perivalvular abscesses.

Assessment of perfusion and wall-motion abnormalities and transient ischemic dilation in regadenoson stress cardiac magnetic resonance perfusion imaging

Vasodilator first-pass stress cardiac magnetic resonance perfusion imaging [stress cardiac magnetic resonance (CMR)] is a reliable, noninvasive method for evaluating myocardial ischemia; however, it does not routinely evaluate metrics such as wall-motion abnormality (WMA) and transient ischemic dilation (TID). Using the new selective A2A adenosine receptor agonist regadenoson, we tested a novel protocol for assessing perfusion defects, WMA, and TID in a single stress CMR session. We evaluated 29 consecutive patients who presented for clinically indicated regadenoson stress CMR. Immediately before and after the regadenoson stress perfusion sequence, we obtained baseline and post-stress cine images in the short-axis orientation to detect worsening or newly developed WMAs. This approach also allowed evaluation of TID. Delayed-enhancement imaging was performed in the standard orientations. All patients tolerated the procedure well. Thirteen patients (45 %) had perfusion abnormalities, and four patients developed TID. Seven patients had WMAs, and three of them also had TID. Patients with TID ± WMAs had multivessel disease documented by coronary angiography. By using regadenoson to assess myocardial ischemia during stress CMR, perfusion defects, WMAs, and TID can be evaluated in a single imaging session. To our knowledge, we are the first to describe this novel approach in a vasodilator stress CMR study.

Functional Magnetic Resonance Imaging of the Lung

Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. Noncontrast-enhanced perfusion imaging is still experimental, either based on arterial spin labeling or Fourier decomposition. The latter is used to separate high- and low-frequency oscillations of lung signal related to the effects of pulsatile blood flow. Lung ventilation: Using contrast-enhanced first-pass perfusion, lung ventilation deficits are indirectly identified by hypoxic vasoconstriction. More direct but still experimental approaches use either inhalation of pure oxygen, an aerosolized contrast agent, or hyperpolarized noble gases. Fourier decomposition MRI based on the low-frequency lung signal oscillation allows for visualization of ventilation without any contrast agent. Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring.

Myocardial perfusion MRI shows impaired perfusion of the mouse hypertrophic left ventricle

There is growing consensus that myocardial perfusion deficits play a pivotal role in the transition from compensated to overt decompensated hypertrophy. The purpose of this study was to systematically study myocardial perfusion deficits in the highly relevant model of pressure overload induced hypertrophy and heart failure by transverse aortic constriction (TAC), which was not done thus far. Regional left ventricular (LV) myocardial perfusion (mL/min/g) was assessed in healthy mice (n = 6) and mice with TAC (n = 14). A dual-bolus first-pass perfusion MRI technique was employed to longitudinally quantify myocardial perfusion values between 1 and 10 weeks after surgery. LV function and morphology were quantified from cinematographic MRI. Myocardial rest perfusion values in both groups did not change significantly over time, in line with the essentially constant global LV function and mass. Myocardial perfusion was significantly decreased in TAC mice (4.2 ± 0.9 mL/min/g) in comparison to controls (7.6 ± 1.8 mL/min/g) (P = 0.001). No regional differences in perfusion were observed within the LV wall. Importantly, increased LV volumes and mass, and decreased ejection fraction correlated with decreased myocardial perfusion (P < 0.001, in all cases). Total LV blood flow was decreased in TAC mice (0.5 ± 0.1 mL/min, P < 0.001) in comparison to control mice (0.7 ± 0.2 mL/min). Myocardial perfusion in TAC mice was significantly reduced as compared to healthy controls. Perfusion was proportional to LV volume and mass, and related to decreased LV ejection fraction. Furthermore, this study demonstrates the potential of quantitative first-pass contrast-enhanced MRI for the study of perfusion deficits in the diseased mouse heart.

Non–ECG‐gated myocardial perfusion MRI using continuous magnetization‐driven radial sampling

Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice two-dimensional imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/s. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7 × 1.7 × 6 mm(3) ) artifact-free FPP images of a single slice at high heart rates (92 ± 21 beats/min), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18 ± 0.70, conventional: 4.88 ± 0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia.

The regional myocardial microvascular dysfunction differences in hypertrophic cardiomyopathy patients with or without left ventricular outflow tract obstruction: Assessment with first-pass perfusion imaging using 3.0-T cardiac magnetic resonance

PurposeTo assess regional myocardial microvascular dysfunction differences in hypertrophic cardiomyopathy (HCM) patients with or without left ventricular outflow tract obstruction using 3.0-T cardiac magnetic resonance (CMR) first-pass perfusion imaging. Materials and methodsForty-two HCM patients, including 25 HCM patients with left ventricular outflow tract obstruction (HOCM), 17 HCM patients without left ventricular outflow tract obstruction (NOHCM), and 14 healthy subjects underwent CMR. The left ventricular (LV) function, left ventricular end-diastolic wall thickness (EDTH), and diameter of left ventricular outflow tract (LVOT) were measured and calculated. Based on the signal–time curve of the first-pass myocardium perfusion imaging, perfusion parameters including upslope, time to peak, and peak intensity, were assessed and compared by using one-way analysis of variance and independent t tests. ResultsOn the first-pass perfusion imaging, lower upslope and peak intensity and longer time to peak were found in HCM patients compared with normal subjects (all p<0.05). In contrast to the NOHCM group, the average time to peak of the HOCM group was increased (13.30±4.82s vs 16.28±4.90s, p<0.05), but first-pass perfusion upslope was reduced (4.96±2.55 vs 2.58±0.77, p<0.05). According to the bull's-eye model, the HOCM group's average thickness of basal segments was thicker than the NOHCM group, especially the anteroseptal, inferolateral, and anterior wall values, with a corresponding lower first-pass perfusion upslope than the NOHCM group (all p<0.05). A significant correlation was observed between first-pass perfusion upslope and LV EDTH (r=−0.551, p<0.001) and LVOT diameter (r=0.472, p<0.001). ConclusionsThe regional myocardial microvascular dysfunction differences in hypertrophic cardiomyopathy (HCM) patients with or without left ventricular outflow tract obstruction can be detected with first-pass perfusion CMR imaging.

Dark-rim-free ungated first-pass perfusion CMR with 3-Slice end-systolic imaging: initial experience

Background First-pass perfusion (FPP) cardiac MR (CMR) imaging has been shown to have a high performance for diagnosis of coronary artery disease (CAD). Reliability of FPP imaging, however, is hindered by dark-rim artifacts (DRAs) and the need for near-perfect ECG gating. The latter can be challenging in the presence of arrhythmias or heart-rate variations during stress. Moreover, endsystolic (ES) imaging has recently been shown to provide improved visualization of subendocardial defects [1]. We developed an innovative ungated FPP technique capable of simultaneously eliminating DRAs [2,3] and enabling reconstruction of all slices at ES. We hypothesized that the developed method achieves DRA-free imaging and high accuracy in patients with suspected CAD, using nuclear myocardial perfusion imaging (MPI) as the reference. Methods Based on the so-called “Ungated Cine FPP” approach [4], a multi-slice magnetization-driven [5-7] method was developed for ungated FPP imaging. Figure 1 highlights the main differences of the proposed pulse sequence compared with the conventional FPP method. All scans were performed on a 3T clinical scanner using an ungated RF-spoiled GRE sequence with continuous golden-angle radial acquisition as in Figure 1b (flip angle = 21°, resolution: 1.7 × 1.7 × 10 mm). The reconstruction method used automatic self-gating and optimally apodized [3] compressed sensing for DRA-free accelerated reconstruction. Normal subjects (n = 6) were studied using both the proposed and conventional methods. Patients (n = 9) with suspected CAD on the basis of recent abnormal SPECT/PET MPI underwent adenosine stress/rest FFP CMR. Three patients returned for a second study using the conventional method. Results The ungated FPP studies in normal subjects were all of high quality and demonstrated normal perfusion. A representative patient study is shown in Figure 2. Stressinduced hypoperfusion was observed in the ES Ungated Cine FPP images, corresponding to a reversible defect on PET MPI (Figure 2b). Figure 2c shows the mid slice for the conventional FPP scan. Based on nuclear MPI studies, sensitivity and specificity of the developed method were 93% and 95%, respectively. The minor disagreements can be explained by the presence of subendocardial defects and possible artifacts on SPECT. All images were reviewed and no DRAs was detected on the Ungated Cine FPP images (2 readers, consensus). However, for the 3 studies using the conventional method, mild-moderate DRA was observed in 21% of the segments. Conclusions Conventional FPP methods are prone to DRAs, require accurate ECG gating, and do not provide the freedom to image all slices at ES. The developed method overcomes these challenges and is an attractive alternative with the advantage of simplicity (no gating), higher accuracy in the subendocardium (no DRAs, ES imaging), and thereby potentially improved reliability. Preliminary results in healthy volunteers and patients with suspected CAD were of high quality and showed high accuracy compared to nuclear MPI.

Early vs. persistent microvascular obstruction following primary PCI- two pathologies or one? A cardiovascular magnetic resonance study

Background 20-40% of reperfused ST-elevation acute myocardial infarction (STEMI) features microvascular obstruction (MO), which confers adverse prognosis. Different CMR sequences are commonly used to detect MO: first pass perfusion (FPP), early gadolinium enhancement (EGE), and late gadolinium enhancement (LGE). FPP and EGE are more sensitive than LGE for the detection of MO. However, only MO by LGE has been shown to confer prognostic information. It is unclear whether these three

Method for correcting respiratory artefacts in parallel-accelerated first-pass myocardial perfusion imaging

Background Myocardial first-pass perfusion (MPI) requires singleshot imaging of multiple slices per cycle. Breath-holding supports advanced high-resolution MPI methods, but tolerance to respiratory motion is desirable. Respiratory misregistration can induce aliasing artefacts by inaccurate coil sensitivity calibration, particularly at higher acceleration factors and during stress hyperpnea. Coil calibration can be adapted for respiratory motion, but autocalibration (integrated”) methods limit acceleration, and temporal coil-calibration methods may reduce SNR or cause temporal smoothing. We evaluated a motiontracking modification of “prescan” parallel imaging specifically for MPI. Methods

Perfusion dephasing discriminated between coronary microvascular disease and multivessels coronary artery disease

Background Non-invasive imaging methods cannot reliably differentiate reliably between coronary microvascular dysfunction (CMD) and multi-vessel coronary artery disease (including left main coronary artery disease; CAD) as both these conditions may result in diffuse myocardial ischemia, which on visual and quantitative analysis can have a similar appearance. Consequently, patients are subjected to invasive angiography, and coronary microvascular dysfunction is diagnosed after demonstrating normal coronary arteries in patients with myocardial ischemia. We hypothesized that the spatial and temporal distribution of the first-pass perfusion of the left ventricular myocardium is fundamentally different between these conditions. The aim of this study was to evaluate the spatial and temporal distribution of perfusion (perfusion dephasing analysis) to differentiate CMD and multivessel CAD. Methods This study included a total of 52 patients. All subjects underwent adenosine-stress first-pass perfusion CMR. Patients with a visually positive perfusion cardiac magnetic resonance (CMR) and functional multivessel disease (fractional flow reserve (FFR) ≤0.8 in at least 2 vessels; n = 25) or a visually positive perfusion CMR and angiographically smooth coronary arteries (CMD Group; n = 27) were included. The datasets were analysed visually, quantified with Fermi deconvolution and assessed for perfusion dephasing (coefficient of variation of the time to peak of the myocardial signal intensity curve). Results Visual and quantitative analysis allowed a reliable diagnosis of significant CAD, but could not distinguish patients with multivessel CAD from patients with CMD as the total extent and severity of ischemia was similar between the two groups. In patients with CAD, perfusion analysis showed significant dephasing proportional to the extent and severity of the epicardial stenoses (average perfusion dephasing in the multivessel CAD group 17% ± 8%). In contrast, in patients with CMD there was very little perfusion dephasing (7% ± 2%;p 10.1% (p < 0.001; area under the ROC curve = 0.96). Conclusions In conclusion, perfusion-dephasing analysis, a novel method to measure temporal differences of myocardial perfusion, is highly accurate in distinguishing patients with functionally significant multivessel CAD from patients with CMD. Funding

Motion-corrected compressed-sensing enables robust spiral first-pass perfusion imaging with whole heart coverage

Background First-pass perfusion imaging using CMR is an important tool for diagnosing coronary artery disease (CAD), but most clinical techniques are limited in their spatial coverage. While compressed-sensing (CS) holds promise for highly accelerated perfusion spiral imaging, CS techniques suffer from blurring artifacts in the setting of respiratory motion. Spiral pulse sequences have multiple advantages for myocardial perfusion imaging including high acquisition efficiency, high signal to noise (SNR) and robustness to motion and for CS including a relatively incoherent aliasing pattern. Thus, we develop a whole heart spiral first-pass perfusion sequence combined with robust motion-correction.

Kardiovaskuläre Magnetresonanztomographie

Cardiovascular magnetic resonance imaging (MRI) has the ability to assess the morphology, function, perfusion and evidence of myocardial scar tissue in a single examination. Moreover, cardiovascular MRI can be carried out with no exposure to radiation. Stress MRI can be performed by assessment of dobutamine-induced wall motion abnormalities or by first-pass adenosine perfusion imaging. Compared to stress echocardiography or single photon emission computed tomography, stress MRI is at least as accurate; however, patients with ferromagnetic materials or other contraindications for MRI, such as intolerance of gadolinium contrast agents cannot be examined. The quality of stress MRI depends on where the examination is being performed and should always be regarded in context to other clinical information, such as from patient history and electrocardiography.

MRXCAT: Realistic numerical phantoms for cardiovascular magnetic resonance

Computer simulations are important for validating novel image acquisition and reconstruction strategies. In cardiovascular magnetic resonance (CMR), numerical simulations need to combine anatomical information and the effects of cardiac and/or respiratory motion. To this end, a framework for realistic CMR simulations is proposed and its use for image reconstruction from undersampled data is demonstrated. The extended Cardiac-Torso (XCAT) anatomical phantom framework with various motion options was used as a basis for the numerical phantoms. Different tissue, dynamic contrast and signal models, multiple receiver coils and noise are simulated. Arbitrary trajectories and undersampled acquisition can be selected. The utility of the framework is demonstrated for accelerated cine and first-pass myocardial perfusion imaging using k-t PCA and k-t SPARSE. MRXCAT phantoms allow for realistic simulation of CMR including optional cardiac and respiratory motion. Example reconstructions from simulated undersampled k-t parallel imaging demonstrate the feasibility of simulated acquisition and reconstruction using the presented framework. Myocardial blood flow assessment from simulated myocardial perfusion images highlights the suitability of MRXCAT for quantitative post-processing simulation. The proposed MRXCAT phantom framework enables versatile and realistic simulations of CMR including breathhold and free-breathing acquisitions.

Accelerated 2D multi-slice first-pass contrast-enhanced myocardial perfusion using through-time radial GRAPPA

Background Non-Cartesian parallel imaging is a promising approach for reducing the scan time in multi-slice first-pass myocardial perfusion imaging, allowing increasing volumetric coverage in comparison with standard techniques. Through-time radial GRAPPA has previously been demonstrated for real-time functional cardiac imaging [Seiberlich, et al. MRM 2011 Feb;65 (2):492-505]. In this work, the through-time radial GRAPPA technique is applied for the acquisition of fifteen slices per heartbeat during a contrast-enhanced myocardial perfusion examination.

Adenosine stress CMR with variable density spiral pulse sequences accurately detects CAD with minimal dark-rim artifacts

Background Adenosine stress CMR perfusion imaging has numerous advantages over competing modalities for assessing CAD demonstrating high diagnostic and prognostic utility. However, adenosine stress CMR perfusion imaging is limited by motion-induced dark-rim artifacts (DRA) which may be mistaken for true perfusion abnormalities. We have previously demonstrated that a high-resolution variable-density spiral pulse sequence with a novel density compensation strategy reduces ringing artifacts in firstpass perfusion imaging. The purpose of this study was to assess the clinical performance of this new technique to detect obstructive coronary artery disease (CAD).