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MR Myocardial Perfusion Imaging with k-Space and Time Broad-Use Linear Acquisition Speed-up Technique: Feasibility Study¹

¹ From the Deutsches Herzzentrum Berlin, Augustenburger Platz 1, 13353 Berlin, Germany (R.G., C.J., I.P., A.B., E.F., E.N.); Philips Medical Systems, Hamburg, Germany (B.S.); and Eidgenössische Technische Hochschule, Zürich, Switzerland (S.K.). Received October 4, 2006; revision requested December 6; revision received January 22, 2007; accepted March 1; final version accepted April 13. Address correspondence to R.G. (e-mail: gebker{at}dhzb.de).

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE References

 
The purpose of this study was to prospectively evaluate the diagnostic accuracy of a cardiovascular magnetic resonance (MR) k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) accelerated perfusion sequence for depicting clinically relevant coronary artery disease (CAD), with use of coronary angiography as the reference standard. The local ethics committee approved this study, and informed consent was obtained from 40 patients (28 men, 12 women; mean age, 61 years ± 8 [standard deviation]) scheduled for coronary catheterization. A balanced steady-state free precession pulse sequence (2.6 x 2.6 x 10 mm) with a net k-t acceleration factor of 3.8 (repetition time msec/echo time msec, 3.2/1.6; flip angle, 50°) was applied. Visual analysis of perfusion images and quantitative analysis of signal-time curves obtained in the myocardium were performed by using segmental myocardial upslope, peak enhancement, and their respective ratios. Visual analysis revealed sensitivity, specificity, and diagnostic accuracy of 86%, 78%, and 83%, respectively, in the detection of coronary stenoses with at least 50% luminal narrowing. Significant (P < .05) changes between ischemic and remote segments could be shown for all perfusion indexes applied. Use of myocardial perfusion imaging with k-t BLAST for accelerated data acquisition is feasible in the identification of patients with substantial CAD (coronary stenosis 50%).

Supplemental material: http://radiology.rsnajnls.org/cgi/content/full/245/3/863/DC1

© RSNA, 2007

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE References

 
In the past decade, there have been extensive developments in myocardial perfusion imaging with cardiovascular magnetic resonance (MR) (1,2). Results of clinical trials have shown that cardiovascular MR perfusion yields good diagnostic results in the detection of coronary artery disease (CAD) compared with coronary angiography (3) or clinically established nuclear techniques (4,5). More recent studies have revealed MR perfusion to have a superior diagnostic accuracy compared with that achieved with single photon emission computed tomography, both in animal studies (6) and in prospective human trials (7,8). Nevertheless, perfusion imaging has remained technically demanding, since the time needed to acquire three short-axis images at high spatial resolution within one heartbeat requires that some compromises be made. These compromises are not easily made, particularly at higher heart rates during stress. Improved hardware settings have allowed for stronger gradients with increased switching rates. However, physiologic constraints, such as the risk of peripheral nerve stimulation, limit further development in this field.

The advent of parallel imaging techniques has led to advances in cardiovascular MR signal processing (9). The k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) was developed to improve the performance of dynamic imaging. Given considerable correlations of typical dynamic data sets in space and time, this technique is used to acquire only a reduced amount of data, and the missing portion of data is recovered afterward (10). Recently, k-t BLAST has been used successfully for other cardiovascular MR functional studies, such as measurement of wall motion (11) and phase-contrast flow (12). We hypothesized that use of k-t BLAST would allow cardiovascular MR perfusion imaging of the myocardium at adequate spatial resolution and high temporal resolution. Thus, the aim of our study was to prospectively evaluate the diagnostic accuracy of a cardiovascular MR k-t BLAST accelerated perfusion sequence for depicting substantial CAD, with use of coronary angiography as the reference standard.

	MATERIALS AND METHODS

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Study Group
This study was approved by the Charité and Virchow-Klinikum (Berlin, Germany) ethics committee. All patients gave written informed consent. Forty-three consecutive patients suspected or known to have CAD who were scheduled for clinically indicated coronary angiography were examined between May and August 2005. Data used in the analysis (see Results section) were obtained in 40 of these patients (28 men, 12 women; mean age, 61 years ± 8 [standard deviation]; age range, 41–78 years).

Study exclusion criteria were contraindications to MR imaging (noncompatible biometallic implants or claustrophobia) or adenosine administration (atrioventricular block more severe than grade I or asthma). Also, patients with arrhythmia and those who had undergone previous coronary artery bypass graft placement were not considered for study inclusion. All patients were instructed to refrain from consuming any caffeinated beverages or foods 24 hours prior to cardiovascular MR. The patients' pertinent medical history, hemodynamic data, and side effects during vasodilator stress were recorded at the time of examination (R.G., C.J., I.P.).

MR Imaging
The k-t BLAST perfusion sequence design.—The main purposes in the design of the pulse sequence were (a) to examine at least three myocardial sections to meet the American Heart Association recommendations for diagnostic cardiac imaging (13); (b) to acquire a complete data set of three myocardial sections at every heartbeat up to a heart rate of at least 120 beats per minute, as this heart rate is often encountered when imaging is performed during vasodilator-induced stress; (c) to achieve an in-plane spatial resolution of at least 3 x 3 mm for assessment of the transmural extent of perfusion deficits; and (d) to keep the sequence settings identical for all patients to allow optimal interindividual comparison of the results.

The basic sequence was a saturation-prepared (100-msec prepulse delay) single-shot balanced steady-state free precession sequence. With use of fivefold undersampling, three short-axis sections with a spatial resolution of 2.6 x 2.6 x 10.0 mm (voxel size, 67.6 mm³) were recorded in a single R-R interval as short as 500 msec to allow imaging at every heartbeat up to a heart rate of 120 bpm. To follow the contrast agent bolus, three short-axis images were acquired during 40 consecutive cardiac cycles. Tsao et al (10) described the details of k-t BLAST. Compared with other applications, such as wall motion imaging, k-t BLAST cardiac imaging involved some changes regarding the order of training data acquisition. Because of the inflow of contrast material, the signal intensity of the images changed with every frame. This necessitated integration of low-resolution training data into the whole imaging scheme in an interleaved fashion, which led to a reduction in the effective k-t acceleration factor (reduced from 5.0 to 3.8) (Fig 1).

View larger version (13K): [in this window] [in a new window] [Download PPT slide]   Figure 1: The k-t sampling pattern used for perfusion imaging consisted of one frame for the training stage and one frame for the acquisition stage for each reconstructed perfusion image. As opposed to the k-t sampling pattern used for wall motion imaging, in which the training and acquisition stages are separated into two breath holds, interleaved integration of the training stage was necessary for perfusion imaging since signal intensity of the images changes with every frame. This led to a reduction in the effective k-t BLAST factor from 5.0 to 3.8. t = time.

Imaging protocol.—Cardiovascular MR was performed with the patient in the supine position by using a 1.5-T MR imager (Intera CV; Philips Medical Systems, Best, the Netherlands) equipped with a Nova gradient system (33 mT/m, 160 [mT · m^–1]/msec) and custom-made software (GyroTools, Zurich, Switzerland) that was based on the imager software (release 11). A five-element cardiac synergy coil was used for signal reception. Cardiac synchronization was performed by using four electrodes placed on the left anterior hemithorax (vector electrocardiography), and imaging was triggered on the R wave of the electrocardiogram (14).

Two 18-gauge cannulas (Becton Dickinson, Heidelberg, Germany) were placed in all patients to allow separate administration of adenosine and contrast material to prevent high-grade atrioventricular blockade during injection of the contrast agent bolus. The patients underwent a standardized cardiovascular MR examination that included the following steps: First, fast survey images were acquired in three standard planes (transverse, sagittal, and coronal) to determine the true short axis of the left ventricle. Second, a transverse, single-angulated single-section cine image of the left ventricle was acquired. Third, a double-angulated single-section cine image of the left ventricle was planned on the previously acquired transverse single-angulated view of the left ventricle. Fourth, cine images were acquired in three short-axis views and three long-axis views (four-, two-, and three-chamber views). The three short-axis views were distributed to cover the heart at the basal, equatorial, and apical positions by adjusting the gap between the sections. The distances between the apical section and the apex and between the basal section and the mitral valve were identical. Fifth, perfusion test images were obtained by using the identical geometry used to acquire the short-axis cine images to carefully exclude any wraparound or trigger artifacts before the actual index test was started. Sixth, stress perfusion imaging was performed by using the described k-t BLAST accelerated perfusion sequence.

Imaging was started in the last minute of adenosine administration (140 µg of adenosine per minute per kilogram of body weight) by injecting an intravenous bolus of 0.05 mmol/kg gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) at a rate of 4 mL/sec followed by a 20-mL saline flush administered at the same rate. Blood pressure and heart rate were monitored continuously during adenosine and contrast agent administration. Patients were instructed to hold their breath for as long as possible during imaging and to breathe shallowly when they could no longer hold their breath. Seventh, rest perfusion imaging was performed by using the same geometry and administering a contrast agent bolus identical to that administered during stress imaging after 15 minutes to allow for myocardial washout. Eighth, standard late gadolinium enhancement was performed 10 minutes after rest perfusion imaging.

Visual Image Analysis
Two experienced readers (C.J., I.P.; 5 and 9 years of experience in cardiovascular MR, respectively) who were blinded to patients' identities and coronary angiography results visually analyzed the perfusion images obtained with the patient at stress and at rest. Image quality with regard to artifacts and blurring (4, excellent; 3, good; 2, moderate; 1, nondiagnostic) was noted subjectively for each patient. Perfusion defects were detected solely with subjective visualization. If a segment showed diminished or delayed contrast material wash-in during stress but not at rest, it was regarded as indicative of obstructive CAD. The readers were instructed to consider defects as artifacts if they appeared during both stress and rest in the epicardium or only briefly (three or fewer frames) in the subendocardium during maximum signal intensity in the left ventricular blood pool before maximum signal intensity in the myocardium was reached. In cases of disagreement between the two observers, a consensus decision was reached.

Signal-to-Noise Ratio
For signal-to-noise ratio (SNR) measurement (B.S., 15 years of experience in cardiovascular MR), two nearly identical images were analyzed with the difference method (15):

where mn(S1 + S2) is the mean value of the region of interest (ROI) in the sum image and std(S1 – S2) is the standard deviation of the region of interest in the difference image.

For SNR measurements, the plateau phases during myocardial enhancement were used. Nearly identical images were obtained by performing a comparison analysis of the time series. Regions of interest were placed over the entire myocardium of the equatorial section in each patient and over the static skeletal muscle near the chest wall. SNR was measured by using a self-written plug-in for ImageJ software (National Institutes of Health, Bethesda, Md).

Quantitative Image Analysis
The signal-time curves of the images were analyzed (R.G., 5 years of experience in cardiovascular MR) with commercially available software (View Forum; Philips Medical Systems). The endocardial and epicardial borders of the myocardium were drawn manually in one representative dynamic frame per section, with the papillary muscles excluded. Since the patients were instructed to hold their breath for as long as possible during the first pass of the contrast agent and the software included an algorithm that corrected for cardiac displacement during breathing, the contours usually could be copied into all other frames of the respective section without needing to perform manual correction. The myocardium of the apical section was divided into four equiangular segments, and the equatorial and basal sections were divided into six segments according to the guidelines provided by the American Heart Association and the American College of Cardiology (13). Normalized signal intensities were obtained by dividing each value by the baseline signal intensity of five unenhanced frames to compensate for surface coil–induced penetration effects. The maximal upslope (four-point linear fit), peak enhancement, and respective stress-rest ratios were calculated for full wall thickness. To correct for differences in input function, the maximal myocardial upslope was normalized by dividing it by the maximal upslope of the left ventricular cavity signal intensity curve. Similarly, peak myocardial enhancement was normalized by dividing it by peak enhancement of the left ventricular cavity. Each segment was assigned to one of the three corresponding coronary arteries (ie, left anterior descending artery, right coronary artery, or left circumflex coronary artery) according to conventional division (13). The myocardial segments belonged to ischemic segments if the feeding coronary artery showed signs of significant stenosis (>50%) at coronary angiography. The segments were remote if they were supplied by normal coronary arteries in patients with obstructive CAD that affected a different coronary artery. Normal segments were those in patients without obstructive CAD.

Coronary Angiography: The Reference Standard
All 40 patients underwent conventional coronary catheterization within 24 hours after the cardiovascular MR examination with use of a standard Judkins technique. Luminal diameter reduction of more than 50% in a major epicardial coronary artery or its major branches (2.5 mm in diameter) was considered a significant stenosis. Angiographic results were classified as being indicative of one-, two-, or three-vessel disease, or they enabled the exclusion of relevant forms of CAD. In patients with substantial CAD, the most severe stenosis was identified by an experienced interventionalist (one of three treating physicians with 8–25 years of experience in coronary angiography) and assigned to the coronary arterial territory (left anterior descending artery, left circumflex artery, or right coronary artery) deemed to be responsible for the perfusion defect.

Statistical Analysis
Statistical analysis was performed with SPSS software (release 12.0.1; SPSS, Chicago, Ill). For all continuous parameters, data are presented as the mean ± standard deviation. All tests were two tailed, and P < .05 indicated significance. We used the paired Student t test to assess significance of hemodynamic data at stress versus rest by using only one value per subject. This value represented the difference between the mean value for observations recorded at rest and the mean value for observations recorded during stress. We used the unpaired Student t test for segment-based image analysis of quantitative image parameters (ie, upslope and peak enhancement at rest and stress). In addition, analysis of variance was used to compare ischemic, remote, and normal segments with respect to the upslope and the peak enhancement ratio. Subject identification was included in the model as a blocking factor to account for statistical dependencies among observations of segments within the same subject. Sensitivity, specificity, and diagnostic accuracy were calculated according to standard definitions. Receiver operating characteristic analyses were performed to evaluate the diagnostic potential of each indicator used for quantitative image analysis.

	RESULTS

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Patient Group
Three of the 43 patients were not evaluated because of patient request (n = 1), bronchospasm during adenosine stress (n = 1), and data storage failure (n = 1). This left 40 patients in the final group (Table 1, Fig 2). Mean heart rate showed a significant (P < .001) increase during adenosine infusion (Table 2), and most patients (n = 31) had minimal side effects (flush and dyspnea). No serious adverse events occurred. There were no significant changes in systolic or diastolic blood pressure (P > .05).

View larger version (13K): [in this window] [in a new window] [Download PPT slide]   Figure 2: Flow diagram shows patient inclusion.

Image Quality and SNR
Overall image quality was good (3.3 ± 0.7). Images were considered diagnostic for all patients both at rest and during stress (visual score 2; Figs 3–5). The mean SNR of the myocardium was 30.1 ± 10.8, whereas the mean SNR of the static muscle was 48.3 ± 13.7.

View larger version (5K): [in this window] [in a new window] [Download PPT slide]   Figure 3: Graph shows overall image quality was good, with a mean score of 3.3 ± 0.7. None of the images were considered nondiagnostic.

View larger version (125K): [in this window] [in a new window] [Download PPT slide]   Figure 4a: k-t BLAST perfusion MR images (3.2/1.6; flip angle, 50°) acquired during adenosine stress in the (a) apical and (b) equatorial ventricular views in a patient suspected of having CAD. A subendocardial stress-induced perfusion defect (arrows) is visible in the anteroseptal, anterior, and anterolateral segments. (c) Invasive coronary angiography was used to confirm subtotal occlusion of the midleft anterior descending artery (arrow).

View larger version (118K): [in this window] [in a new window] [Download PPT slide]   Figure 4b: k-t BLAST perfusion MR images (3.2/1.6; flip angle, 50°) acquired during adenosine stress in the (a) apical and (b) equatorial ventricular views in a patient suspected of having CAD. A subendocardial stress-induced perfusion defect (arrows) is visible in the anteroseptal, anterior, and anterolateral segments. (c) Invasive coronary angiography was used to confirm subtotal occlusion of the midleft anterior descending artery (arrow).

View larger version (166K): [in this window] [in a new window] [Download PPT slide]   Figure 4c: k-t BLAST perfusion MR images (3.2/1.6; flip angle, 50°) acquired during adenosine stress in the (a) apical and (b) equatorial ventricular views in a patient suspected of having CAD. A subendocardial stress-induced perfusion defect (arrows) is visible in the anteroseptal, anterior, and anterolateral segments. (c) Invasive coronary angiography was used to confirm subtotal occlusion of the midleft anterior descending artery (arrow).

View larger version (117K): [in this window] [in a new window] [Download PPT slide]   Figure 5a: (a) k-t BLAST MR perfusion image (3.2/1.6; flip angle, 50°) acquired during adenosine stress in the basal view in a patient suspected of having CAD shows a subendocardial inferior perfusion defect (arrows). (b) Invasive coronary angiography enabled us to confirm the presence of subtotal occlusion of the distal right coronary artery (arrow).

View larger version (174K): [in this window] [in a new window] [Download PPT slide]   Figure 5b: (a) k-t BLAST MR perfusion image (3.2/1.6; flip angle, 50°) acquired during adenosine stress in the basal view in a patient suspected of having CAD shows a subendocardial inferior perfusion defect (arrows). (b) Invasive coronary angiography enabled us to confirm the presence of subtotal occlusion of the distal right coronary artery (arrow).

Upslope ratio.—There was a significant difference in mean upslope ratio between ischemic segments (0.98 AU ± 0.41) and remote (1.70 AU ± 0.71, P < .001) and normal (1.73 AU ± 0.79, P < .001) segments (Table 3). The area under the receiver operating characteristic curve was 0.83 (95% confidence interval: 0.79, 0.88). Receiver operating characteristic curve analysis showed that an upslope ratio threshold of 1.24 yielded the highest average value of sensitivity and specificity. At this threshold, sensitivity was 78% and specificity was 71% (Fig 6).

View larger version (12K): [in this window] [in a new window] [Download PPT slide]   Figure 6: Receiver operating characteristic curves of upslope (left) and peak enhancement (right) ratios show a larger area under the curve for the upslope ratio (0.83 vs 0.61).

Peak enhancement ratio.—There were significant differences between mean ischemic segment (1.32 AU ± 0.61) and remote (1.53 AU ± 0.58, P = .008) and normal (1.55 AU ± 0.84, P = .03) segment values (Table 3). The area under the receiver operating characteristic curve for peak enhancement ratio was 0.61 (95% confidence interval: 0.54, 0.69) (Fig 6).

	DISCUSSION

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The results of our prospective study show that use of k-t BLAST to speed up data acquisition for cardiovascular MR perfusion imaging is feasible at adequate spatial and high temporal resolutions. The implementation of k-t BLAST is associated with good diagnostic accuracy (83%) in the identification of patients with relevant CAD when both visual and quantitative analyses are used.

The k-t BLAST approach has been suggested as a promising technique to speed up imaging of cardiac wall motion at rest (11) and stress (16) and to perform flow measurement (12); however, to our knowledge, it has not been evaluated for use in the assessment of myocardial perfusion imaging. Application of this technique seems promising, since the expected reduction in SNR is small relative to the acceleration achieved. The results of studies in which the balanced steady-state free precession technique has been compared directly with spoiled gradient-recalled-echo and segmented echo-planar imaging techniques have shown the superiority of steady-state free precession in terms of SNR, contrast-to-noise ratio, and image quality (17–19). Thus, in our study, we combined the potential to accelerate imaging by using k-t BLAST with balanced steady-state free precession.

We used the properties of k-t BLAST to attain adequate high spatial resolution (67.6-mm³ voxel) with a coverage of three sections per heartbeat combined with a short (500-msec) imaging time, thereby allowing imaging at a heart rate of up to 120 beats per minute. Alternatively, a focus can be placed on larger myocardial volumes (more sections) at the expense of either spatial or temporal resolution. In patients with high heart rates during vasodilator stress, it often becomes necessary to reduce the number of myocardial sections (20), reduce the spatial resolution, prolong the acquisition time per heartbeat, or reduce the temporal resolution to obtain images at only every other heartbeat (21). Any of these actions might lead to lower sensitivity in CAD detection. In other trials, researchers have pointed out the effects of missing dynamic images on diagnostic accuracy in myocardial perfusion reserve index calculation (22). All patients in our study could be examined by using the described method without reduced spatial or temporal resolution. Furthermore, the in-plane spatial resolution of 2.6 x 2.6 mm was comparable to that in previous studies (23).

With use of parallel imaging techniques, such as sensitivity encoding, there are further limitations given that the SNR penalty can be substantial with use of higher sensitivity-encoding factors. With use of k-t BLAST, SNR varies spatially depending on the temporal bandwidth required in each spatial location. While highly dynamic image voxels show the expected decrease in SNR by a factor of 1/R², with R denoting the acceleration factor, fully static areas exhibit improved SNR, given in the equation (D)/(R), with D being the number of dynamic image frames recorded (40 image frames were recorded in our study). Theoretically, SNR of the static muscle should be 2.8-fold higher than SNR of the dynamic myocardium. The measured factor in our study, however, was only 1.6. This difference is most likely a result of the higher contrast enhancement of the myocardium during the first pass of the contrast agent bolus. Our results are in concordance with the findings of other studies in which myocardial SNR in cardiovascular MR perfusion imaging was investigated (17).

The use of visual (24) and quantitative (25,26) approaches to assess cardiovascular MR perfusion studies has proved to be clinically valid and practical. The inclusion criteria in our study were not as strict as those in other perfusion trials, in which patients with arterial hypertension, diabetes mellitus, or previous myocardial infarction were excluded (1,26). In addition, no patients were excluded because of insufficient image quality, as in previous multicenter trials (27). In a recent study in which an interpretation algorithm of a comprehensive cardiovascular MR protocol was investigated, researchers found that the combination of delayed-enhancement imaging and perfusion imaging is superior to perfusion imaging alone in the detection of CAD (24). As a result of the high specificity of delayed-enhancement imaging, matched stress-rest perfusion defects in the absence of infarction that were identified with delayed-enhancement imaging were considered artifactual. The overall quality of the perfusion images in our study, however, was good, resulting in good diagnostic accuracy (83%) in the identification of patients with relevant CAD. None of the patients were excluded from visual or quantitative analysis because of artifacts or poor SNR.

Our results show that quantitative analysis of signal intensity curves can be performed with a k-t BLAST accelerated perfusion sequence. The analysis methods that we used characterize signal intensity curves in terms of maximal upslope, peak enhancement, and their respective ratios. The results of animal studies show there is a strong correlation between myocardial perfusion measured with radiolabeled microspheres and the maximal upslope (28). Furthermore, results of clinical studies show that these values reflect myocardial perfusion reserve with high accuracy and reproducibility. Similar to findings of previous studies (29), the peak enhancement ratio was inferior to the upslope ratio in ischemia detection.

A limitation of our study is that after an initial test phase, no further adaptation of the imaging parameters, such as echo time, repetition time, flip angle, or prepulse delay, was performed to improve image quality. Furthermore, no direct comparison with other cardiovascular MR perfusion sequences was performed. Future studies are needed to evaluate the applicability of k-t perfusion imaging in larger patient populations and to determine the diagnostic accuracy of this technique compared with that of other perfusion techniques. We did not incorporate other cardiovascular MR imaging modalities, such as those that allow evaluation of wall motion or delayed enhancement, into our analysis scheme. Other researchers recently proposed the use of these modalities, and the inclusion of these modalities might have improved the overall diagnostic accuracy of this study (24). We used conventional angiography to determine if relevant CAD was present in the patient population, as did investigators in most previous studies (9,26). Conventional angiography is not the ideal reference standard, as it yields only an indirect estimate of the flow limitation caused by coronary stenosis; however, it is the most clinically important reference examination, and the results of this examination are the basis for patient treatment.

In summary, our results show that acceleration of cardiovascular MR perfusion imaging with k-t BLAST is feasible and associated with good diagnostic accuracy (83%) in the detection of relevant CAD. Further studies are needed to evaluate k-t BLAST perfusion imaging and its relationship to other cardiovascular MR and nuclear perfusion techniques. Improved spatial and temporal resolution may permit more reliable and robust diagnostic stress perfusion imaging.

	ADVANCES IN KNOWLEDGE

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE References

 

• Myocardial perfusion imaging with use of the k-space and time (k-t) broad-use linear acquisition speed-up technique (BLAST) for accelerated data acquisition is feasible at a high temporal resolution.
  
• On the basis of visual and quantitative assessment, k-t BLAST accelerated cardiovascular perfusion MR imaging has good diagnostic accuracy (83%) in the detection of substantial coronary artery disease.
  

	FOOTNOTES

 

Abbreviations: AU = arbitrary unit • BLAST = broad-use linear acquisition speed-up technique • CAD = coronary artery disease • k-t = k-space and time • SNR = signal-to-noise ratio

Author contributions:Guarantors of integrity of entire study, R.G., E.N.; study concepts/study design or data acquisition or data analysis/interpretation, all authors; manuscript drafting or manuscript revision for important intellectual content, all authors; manuscript final version approval, all authors; literature research, R.G., C.J., I.P., B.S., S.K., A.B., E.N.; clinical studies, R.G., C.J., I.P.; statistical analysis, R.G., E.N.; and manuscript editing, all authors

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TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS DISCUSSION ADVANCES IN KNOWLEDGE References

 

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