MR fingerprinting using the quick echo splitting NMR imaging technique.

PURPOSE: The purpose of the study is to develop a quantitative method for the relaxation properties with a reduced radio frequency (RF) power deposition by combining magnetic resonance fingerprinting (MRF) technique with quick echo splitting NMR imaging technique (QUEST). METHODS: A QUEST-based MRF sequence was implemented to acquire high-order echoes by increasing the gaps between RF pulses. Bloch simulations were used to calculate a dictionary containing the range of physically plausible signal evolutions using a range of T1 and T2 values based on the pulse sequence. MRF-QUEST was evaluated by comparing to the results of spin-echo methods. The specific absorption rate (SAR) of MRF-QUEST was compared with the clinically available methods. RESULTS: MRF-QUEST quantifies the relaxation properties with good accuracy at the estimated head SAR of 0.03 W/kg. T1 and T2 values estimated by MRF-QUEST are in good agreement with the traditional methods. CONCLUSIONS: The combination of the MRF and the QUEST provides an accurate quantification of T1 and T2 simultaneously with reduced RF power deposition. The resulting lower SAR may provide a new acquisition strategy for MRF when RF energy deposition is problematic. Magn Reson Med 77:979-988, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

3.0T whole-heart coronary magnetic resonance angiography performed with 32-channel cardiac coils: a single-center experience.

BACKGROUND: Whole-heart coronary magnetic resonance angiography (MRA) is a promising method for noninvasive, radiation-free detection and exclusion of obstructive coronary artery disease; however, the required imaging time and robustness of the technique are not yet satisfactory. We evaluated the value of whole-heart coronary MRA at 3.0T using a 32-channel cardiac coil, which reduces image-acquisition times and hence allows to increase the clinical throughput. METHODS AND RESULTS: A total of 110 consecutive patients with suspected coronary artery disease referred for clinically indicated conventional coronary angiography were included in this prospective study. Acquisition of 3.0T coronary MRA data was done by using 32-channel receiver coils. An ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used for image acquisition with an acceleration factor of 3 in the phase-encoding direction using generalized auto calibrating partially parallel acquisitions reconstruction. Acquisition of coronary MRA was successfully completed in 101 of 110 (92%) patients with average imaging time of 7.0±1.8 minutes. The sensitivity, specificity, positive and negative predictive value of coronary MRA on a patient-based analysis were 95.9% (47/49, 95% CI, 86.0%-99.4%), 86.5% (45/52, 95% CI, 74.2%-94.4%), 87.0% (47/54, 95% CI, 75.1%-94.6%) and 95.7% (45/47, 95% CI, 85.4%-99.4%), respectively. CONCLUSIONS: Whole-heart coronary MRA at 3.0T using a 32-channel cardiac coil allows high overall accuracy for detecting significant coronary artery disease with reduced imaging time. It has potential to be a robust and alternative technique for ruling out significant coronary artery disease. CLINICAL TRIAL REGISTRATION: URL: http://www.chictr.org. Unique identifier: ChiCTR-DDT-07000121.

Accuracy of MRI to identify the coronary artery plaque: a comparative study with intravascular ultrasound.

PURPOSE: To evaluate the ability of black-blood coronary arterial wall MRI to identify the coronary artery plaque, using intravascular ultrasound (IVUS) as the golden standard. MATERIALS AND METHODS: Nineteen consecutive patients underwent IVUS and coronary artery wall MRI. Cross-sectional images were acquired on the lesion of coronary artery from the ostium to the middle segment continuously. The vessel cross-sectional area (CSA), luminal CSA, plaque burden, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were measured in each slice which was then compared with the IVUS images. RESULTS: Sixteen of 19 patients completed coronary artery MRA and wall imaging. 41 of 67 slices were found plaques on both IVUS and MRI; The maximal wall thickness, plaque burden, SNR, CNR in the coronary wall containing plaque were greater compared with the normal coronary wall (1.70 ± 0.51 versus 1.24 ± 0.24; 0.71 ± 0.13 versus 0.59 ± 0.12; 1.86 ± 0.41 versus 1.47 ± 0.23; 5.10 ± 2.21 versus 2.99 ± 1.17; respectively, P < 0.05). The matched MRI and IVUS showed good correlation for vessel CSA (16.77 ± 10.67 versus 16.97 ± 8.36; r = 0.79; P < 0.01), luminal CSA (5.18 ± 5.01 versus 7.13 ± 5.14; r = 0.88; P < 0.01), plaque burden (0.71 ± 0.13 versus 0.59 ± 0.15; r = 0.67; P < 0.01). in segments containing plaques, especially the luminal CSA were strongly correlated. CONCLUSION: MRI coronary artery wall imaging can identify coronary plaque in the proximal segments. It also has the potential to assess coronary artery size.

Use of coronary anatomy and late enhancement information both derived from contrast-enhanced whole-heart coronary MRA at 3 T for the assessment of ischemic left ventricular dysfunction.

Recognizing the etiology of patients with left ventricular dysfunction (LVD) is essential for the risk stratification and treatment selection. We report the case of a 59-year-old man suspected of ischemic LVD with non acute symptoms studied with whole-heart cardiac magnetic resonance imaging including noninvasive coronary angiography and in whom we obtained comprehensive information of both coronary artery stenosis and myocardial tissue damage.

The relative atrial volume ratio and late gadolinium enhancement provide additive information to differentiate constrictive pericarditis from restrictive cardiomyopathy.

BACKGROUND: The differentiation of constrictive pericarditis (CP) from restrictive cardiomyopathy (RCM) is often difficult. This study sought to determine the clinical utility of cardiovascular magnetic resonance imaging (CMR) for differentiating both these disorders. METHODS: Twenty-three patients with surgically documented CP, 22 patients with RCM and 25 normal subjects were included in the study. CMR yielded information about cardiac morphology, function and tissue characteristics. The left (LA) and right atrial (RA) volume was calculated using the area-length method. The relative atrial volume ratio (RAR) was defined as the LA volume divided by RA volume. Receiver operating characteristic curve analysis was used to test the ability of different variables in differentiating CP from RCM. RESULTS: The maximal pericardial thickness in CP patients was significantly larger than in normal subjects and RCM patients. The RA volume index in RCM patients (90.5 ± 35.3 mL/m2) was significantly larger than in CP patients (71.4 ± 15.7 mL/m2, p = 0.006) and normal subjects (38.1 ± 9.0 mL/m2, p < 0.001). The LA volume index in RCM (96.0 ± 37.0 mL/m2) and CP patients (105.6 ± 25.1 mL/m2) was significantly larger than in normal subjects (39.5 ± 9.5 mL/m2, p < 0.001 for all). The RAR in CP patients (1.50 ± 0.29) was significantly larger than in RCM patients (1.12 ± 0.33, p < 0.001) and normal subjects (1.06 ± 0.20, p < 0.001). There were no differences between RCM patients and normal subjects in the RAR (p = 0.452). At a cut-off value of 1.32 for the RAR, the sensitivity was 82.6%, and the specificity was 86.4% in the detection of CP. Septal bounce was identified in 95.7% CP patients, in none of RCM patients and normal subjects. Late gadolinium enhancement (LGE) was present in 31.8% RCM patients and absence in all CP patients and normal subjects. CONCLUSIONS: CMR with LGE and RAR can facilitate differentiation of CP from RCM.

Contrast-enhanced whole-heart coronary MRA at 3.0T for the evaluation of cardiac venous anatomy.

This study was designed to evaluate the value of contrast-enhanced whole-heart coronary MRA (CMRA) at 3.0T in depicting the cardiac venous anatomy. In cardiac resynchronization therapy (CRT), left ventricular (LV) pacing is achieved by positioning the LV lead in one of the tributaries of the coronary sinus (CS). Pre-implantation knowledge of the venous anatomy may help determine whether transvenous LV lead placement for CRT is feasible. Images of 51 subjects undergoing contrast-enhanced whole-heart CMRA at 3.0T were retrospectively analyzed. Data acquisition was performed using electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence. A 32-element cardiac coil was used for data acquisition. The visibility of the cardiac veins was graded visually using a 4-point scale (1: poor-4: excellent). The paired Student t test was used to evaluate differences in diameters of the ostium of the CS in anteroposterior and superoinferior direction. The cardiac veins were finally evaluated in 48 subjects with three anatomic variations. The diameter of the CS ostium in the superoinferior direction (1.13 ± 0.26 cm) was larger than in the anteroposterior direction (0.82 ± 0.19 cm) (P < 0.05). The mean visibility score of CS, posterior interventricular vein, posterior vein of the left ventricle, left marginal vein, and anterior interventricular vein was 4.0 ± 0.0, 3.4 ± 0.5, 3.4 ± 0.5, 3.0 ± 0.8, and 3.3 ± 0.5, respectively. In conclusion, contrast-enhanced whole-heart CMRA at 3.0T can depict the normal and variant cardiac venous anatomy.

Cardiac magnetic resonance imaging characteristics of isolated left ventricular noncompaction in a Chinese adult Han population.

To analyze cardiac magnetic resonance imaging (CMR) characteristics in patients with isolated left ventricular noncompaction (IVNC) and assess its value in the diagnosis of IVNC in a Chinese adult Han population. We collected a consecutive series of 30 patients with IVNC from January 1, 2007, to December 31, 2008. During the same period, we prospectively included patients drawn from groups given a potential differential diagnosis for IVNC. All magnetic resonance images were analyzed using 17-segment model. Left ventricular ejection fraction was significantly lower for patients with DCM (16.2 ± 5.2%, P < 0.001) and higher in AR (47.6 ± 16.2%, P = 0.009), AS (54.6 ± 21.1%, P = 0.001) and HHD (62.4 ± 6.8%, P < 0.001) compared with IVNC (33.0 ± 14.1%). The two-layered structure was most frequently seen at the apical segments, followed by the mid-cavity and basal segments in patients with INVC. The anterior and lateral walls were more commonly involved in patients with IVNC. The number of noncompacted segments and end-diastolic ratio of non-compacted to compacted myocardium (NC/C ratio) was greater in patients with IVNC than in other five groups. The end-diastolic NC/C ratio of >2.5 had 96.4% sensitivity and 97.4% specificity for identifying patients with IVNC. CMR provides an accurate and reliable evaluation of the localization and extent of noncompacted myocardium at end-diastole. The end-diastolic NC/C ratio of >2.5 had high diagnostic accuracy for IVNC in a Chinese adult Han population.

Assessment of cardiac morphology and ventricular function in healthy Chinese individuals using MRI / 中华放射学杂志

ObjectiveTo investigate reproducibility of cardiac MRI for assessment of cardiac morphology and ventricular function in selected normal Chinese Han population.MethodsTwo hundred and sixty-nine normal volunteers underwent cardiac MRI using a 1.5 T MR system.HASTE and steady state free precession imaging were performed with long and short axis images and cine mode through the ventricle with wireless vector cardiac gating.The images were reviewed by two independent observers.The dimensions of cardiac chambers and ventricular function including ejection fraction (EF),end diastolic volume( EDV),end systolic volume (ESV) and myocardial mass were evaluated.The data between male and female were compared by using two-tailed unpaired t test.Results Total imaging time was (15 ± 3 ) min.The anteroposterior diameter of the left atrium was( 2.87 ± 0.77 ) cm,the right atrial diameter perpendicular to the atrial septum was ( 3.61 ± 0.57 ) cm,the end diastolic diameter of the left ventricle was (4.97 ±0.52) cm,the end diastolic diameter of the right ventricle was (2.65 ± 0.48) cm.On the left ventricle,EF was(60.62 ±7.08)％,EDV was (115.37 ±26.71) ml,ESV was (46.02+15.72) ml and LV mass was ( 82.97± 24.03 ) g.On the right ventricle,EF was (47.73 ± 6.50 ) ％,EDV was ( 128.27 ± 32.16 )ml,ESV was (67.7 ± 21.07) ml and RV mass was (48.24 ± 13.42) g.There were no statistically significant differences in LVESV( P =0.144 ),LVEDV index ( P =0.714 ),LVESV index ( P =0.113 ),LVCI ( P =0.199),RVEF ( P =0.296 ) and RV mass ( P =0.093 ),and statistically significant differences in other cardiac parameters between male and female.Conclusion Cardiac MRI can provide useful information about cardiac function and morphology with a high level of reproducibility in normal Chinese Han population.

Contrast-kinetics-resolved whole-heart coronary MRA using 3DPR.

Slow contrast infusion was recently proposed for contrast-enhanced whole-heart coronary MR angiography. Current protocols use Cartesian k-space sampling with empiric acquisition delays, potentially resulting in suboptimal coronary artery delineation and image artifacts if there is a timing error. This study aimed to investigate the feasibility of using time-resolved three-dimensional projection reconstruction for whole-heart coronary MR angiography. With this method, data acquisition was started simultaneously with contrast injection. Sequential time frames were reconstructed by employing a sliding window scheme with temporal tornado filtering. Additionally, a self-timing method was developed to monitor contrast enhancement during a scan and automatically determine the peak enhancement time around which optimal temporal frames were reconstructed. Our preliminary results on six healthy volunteers showed that by using time-resolved three-dimensional projection reconstruction, the contrast kinetics of the coronary artery system throughout a scan could be retrospectively resolved and assessed. In addition, the blood signal dynamics predicted using self-timing was closely correlated to the true dynamics in time-resolved reconstruction. This approach is useful for optimizing delineation of each coronary artery and minimizing image artifacts for contrast-enhanced whole-heart MRA.

Non-contrast-enhanced four-dimensional (4D) intracranial MR angiography: a feasibility study.

T(1)-shortening contrast agents have been widely used in time-resolved magnetic resonance angiography. To match imaging data acquisition with the short time period of the first pass of contrast agent, temporal resolution and/or spatial resolution have to be compromised in many cases. In this study, a novel non-contrast-enhanced technique was developed for time-resolved magnetic resonance angiography. Alternating magnetization preparation was applied in two consecutive acquisitions of each measurement to eliminate the need for contrast media. Without the constraint of contrast media kinetics, temporal resolution is drastically improved from the order of a second as in conventional contrast-enhanced approach to tens of milliseconds (50.9 msec) in this study, without compromising spatial resolution. Initial results from volunteer studies demonstrate the feasibility of this method to depict anatomic structure and dynamic filling of main vessels in the head.

Evaluation of cardiac venous anatomy with contrast-enhanced whole-heart coronary MR angiography at 3. 0 T / 中华放射学杂志

Objective To evaluate the value of contrast-enhanced whole-heart coronary magnetic resonance angiography ( CE CMRA ) at 3.0 T in the delineation of cardiac venous anatomy. Methods Contrast-enhanced whole-heart CMRA at 3.0T was performed in 43 consecutive subjects using ECG-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence with a 32-channel cardiac coil. The visibility of the coronary veins was graded visually using a 4-point scale.Continuous variable was expressed as (-x)±s. The paired student t test was used to evaluate the differences of the coronary sinus (CS) ostium diameter in anteroposterior and superoinferior directions. Results CMRA examination was successfully completed in 40 subjects with acquisition time of ( 6. 9 ± 1.8 ) min. The cardiac veins were finally evaluated in 38 of 40 (95.0%) subjects. The mean distance of the posterior vein of the left ventricle (PVLV) and the left marginal vein (LMV) to the CS ostium were (3.34 ± 0. 90) and (6. 12 ± 1.02) cm, respectively. The mean visibility scores of CS, posterior interventricular vein (PIV),PVLV, LMV, and anterior interventricular vein (AIV) were 4.0 ± 0.0, 3.4 ± 0. 5, 3.4 ± 0. 5, 3.0 ± 0. 8,and 3. 3 ± 0. 5, respectively. The diameter of the CS ostium in the superoinferior direction ( 1.13 ±0. 26) cm was larger than that in the anteroposterior direction (0. 82 ± 0. 19) cm (t = -4. 31 ,P <0. 05).Conclusion Contrast-enhanced whole-heart CMRA at 3.0 T can clearly depict the cardiac venous anatomy.

Three-dimensional phase-sensitive inversion-recovery turbo FLASH sequence for the evaluation of left ventricular myocardial scar.

OBJECTIVE: The purpose of this study was to evaluate a new free-breathing 3D phase-sensitive inversion-recovery (PSIR) turbo FLASH pulse sequence for the detection of left ventricular myocardial scar. SUBJECTS AND METHODS: Patients with suspected myocardial scar were examined on a 1.5-T MR scanner for myocardial late enhancement after the administration of gadopentetate dimeglumine using a segmented 2D PSIR turbo FLASH sequence followed by a navigator-gated 3D PSIR turbo FLASH sequence. Image quality was scored by two independent readers using a 4-point Likert scale (0 = poor, nondiagnostic; 1 = fair, diagnostics may be impaired; 2 = good, some artifacts but not interfering in diagnostics; 3 = excellent, no artifacts). Scars were compared quantitatively in volume and graded qualitatively on the basis of size (area) and location. RESULTS: Thirty-three patients were scanned using both techniques. In 25 patients, the quality of the 3D PSIR images was acceptable. Scars were detected in 12 patients. Hyperenhanced scar volumes (p = 0.43), qualitative analysis of scar area (p = 0.78), and scar location (p = 0.68) were similar for both techniques. More small hyperenhanced scars, corresponding mostly to nonischemic distribution patterns, were detected using 3D PSIR than 2D PSIR. Although 2D and 3D results were found to be highly correlated for scar volume, Bland-Altman analysis indicated a systematic smaller infarct volume on the 2D PSIR scans (R(2) = 0.84). CONCLUSION: Free-breathing 3D PSIR turbo FLASH imaging is a promising technique for the assessment of left ventricular scar particularly for scar quantification and the detection of small nonischemic scars in the myocardium.

Three-dimensional T2-weighted MRI of the human femoral arterial vessel wall at 3.0 Tesla.

OBJECTIVES: To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0 T. BACKGROUND: Magnetic resonance imaging can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. Although black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed. METHODS: Fifteen healthy volunteers and 3 patients with peripheral arterial disease (PAD) underwent 3D SPACE imaging of the superficial femoral artery at 3.0 T, with the conventional 2D TSE T2w imaging as a reference. Muscle-lumen contrast to noise ratio (CNR) and wall/lumen volumes (WV, LV) were measured at the matched locations on the 3D and 2D image sets. Statistical comparison on a per-subject basis was conducted to determine the difference and agreement between 3D SPACE and the 2D TSE techniques. RESULTS: The 3D SPACE data sets enabled vessel visualization from arbitrary orientation through multiplanar reformation technique. Muscle-lumen CNR was significantly higher with 3D SPACE than with the 2D TSE (3.12 +/- 0.84 vs. 2.17 +/- 0.34, P < 0.01). This trend was confirmed when CNR efficiency (CNR(eff)) values were further compared. A similar trend was observed in PAD patients (SPACE vs. 2D TSE T2w: CNR 2.35 +/- 0.13 vs. 1.77 +/- 0.25; CNR(eff) 15.35 +/- 0.61 vs. 3.59 +/- 2.62. all P < 0.05). Measurements of WV and LV from the 3D and 2D techniques were highly correlated in volunteers and PAD patients (volunteers, WV: linear regression r2 = 0.98, LV: r2 = 0.98, P < 0.001 for both; patients, WV: linear regression r2 = 0.96, LV: r2 = 0.94, P < 0.001 for both). CONCLUSION: We established the feasibility of using the 3D SPACE technique for vessel wall imaging in the superficial femoral artery at 3.0T. High, isotropic-resolution SPACE images, with the aid of multiplanar reformation, enable superior vessel wall visualization. Superior blood signal suppression comparable to vessel wall morphologic measurements, and superior time efficiency compared to conventional 2D TSE imaging indicate the great potential of the SPACE method as a noninvasive imaging technique for the assessment of atherosclerotic plaque burden in PAD patients.

A respiratory self-gating technique with 3D-translation compensation for free-breathing whole-heart coronary MRA.

Respiratory motion remains a major challenge for robust coronary MR angiography (MRA). Diaphragmatic navigator (NAV) suffers from indirect measurement of heart position. Respiratory self-gating (RSG) approaches improve motion detection only in the head-feet direction, leaving motion in the other two dimensions unaccounted for. The purpose of this study was to extend conventional RSG (1D RSG) to RSG capable of 3D motion detection (3D RSG) by acquiring additional RSG projections with transverse-motion-encoding gradients. Simulation and volunteer studies were conducted to validate the effectiveness of this new method. Preliminary comparison was performed between coronary artery images reconstructed from the same datasets using different motion correction methods. Our simulation illustrates that a proper motion-encoding gradient and derivation method enable accurate 3D motion detection. Results from whole-heart coronary MRA show that 3D RSG can further reduce motion artifacts as compared to NAV and 1D RSG and enables use of larger gating windows for faster coronary imaging.

Contrast-enhanced whole-heart coronary magnetic resonance angiography at 3.0-T: a comparative study with X-ray angiography in a single center.

OBJECTIVES: The purpose of this study was to prospectively evaluate the diagnostic performance of 3.0-T contrast-enhanced whole-heart coronary magnetic resonance angiography (CMRA) in patients with suspected coronary artery disease (CAD). BACKGROUND: A slow-infusion, contrast-enhanced whole-heart CMRA approach has recently been developed at 3.0-T. The accuracy of this technique has not yet been determined among patients with suspected CAD. METHODS: The 3.0-T contrast-enhanced whole-heart CMRA was performed in 69 consecutive patients. An electrocardiography-triggered, navigator-gated, inversion-recovery prepared, segmented gradient-echo sequence was used to acquire isotropic whole-heart CMRA with slow infusion of 0.2 mmol/kg gadobenate dimeglumine. The diagnostic accuracy of whole-heart CMRA in detecting significant stenoses (> or =50%) was evaluated using X-ray angiography as the reference. RESULTS: The CMRA examinations were successfully completed in 62 patients. Acquisition time of whole-heart CMRA procedure was 9.0 +/- 1.9 min. The 3.0-T whole-heart CMRA correctly identified significant CAD in 32 patients and correctly ruled out CAD in 23 patients. The sensitivity, specificity, and accuracy of whole-heart CMRA for detecting significant stenoses were 91.6% (87 of 95), 83.1% (570 of 686), and 84.1% (657 of 781), respectively, on a per-segment basis. These values were 94.1% (32 of 34), 82.1% (23 of 28), and 88.7% (55 of 62), respectively, on a per-patient basis. CONCLUSIONS: Contrast-enhanced whole-heart CMRA with 3.0-T allows for the accurate detection of coronary artery stenosis with high sensitivity and moderate specificity.

Cardiac image modeling tool for quantitative analysis of global and regional cardiac wall motion.

OBJECTIVE: To evaluate the Cardiac Image Modeling (CIM 4.6; University of Auckland, Auckland, New Zealand) tool's ability to assess cardiac function via quantitative calculations of global and regional ejection fraction (EF) from magnetic resonance imaging in comparison with a current method of global analysis with Argus (Siemens Medical Solutions) and regional analysis with visual analysis. BACKGROUND: Global cardiac function is commonly assessed quantitatively by post processing tools that calculate global EF. Currently, regional cardiac function is assessed by subjective visual analysis of wall motion, which can have significant interobserver variability. CIM is a tool that may reduce variability by generating a semi-automated 3-dimensional heart model to calculate quantitative global and regional EF. MATERIALS AND METHODS: Thirty-one patients (22 men, 9 women; mean age 55.1 +/- 17.5 years) were selected based on global EFs calculated at the time of the clinical visit with the Argus postprocessing tool (Siemens Medical Solutions). Patients were then placed into 2 predetermined categories of normal: EF >or=50% and abnormal: EF <50%. Regional EF was calculated for each segment of a 16-segment cardiac model. Three blinded reviewers used the standard of care assessment of regional function, which was a qualitative grading of the 16 segments into categories of normal or abnormal regional wall motion by visual analysis. CIM quantitatively analyzed global EF and regional EF for each segment. These segments were then sorted into the predetermined categories of normal (EF >or=50%) and abnormal (EF <50%). Level of agreement was conducted via Pearson correlation coefficient and Bland-Altman analysis for global EF analysis and observed proportion of agreement (p(a)), sensitivity, and specificity for regional EF analysis. RESULTS: Global EF analysis showed a high correlation (r2 = 0.85; y = 0.94x + 4.85, P < 0.001) between the Argus and CIM analyses. Sixteen-segment regional EF analysis showed p(a) averages >0.60. Regional wall motion by short axis slices showed pa averages >0.75, and combined analyses of all 3 reviewers' 16-segment regional data showed an overall total p(a) = 0.79 (sensitivity = 72%, specificity = 88%). Interobserver and intraobserver variability were low (p(a) > 0.65) in this study. CONCLUSIONS: Global EF analysis of cardiac magnetic resonance imaging by CIM showed high agreement with the commonly used Argus postprocessing tool. Furthermore, CIM is capable of evaluating regional EF with good agreement in comparison with the current visual method. In addition to determining abnormal versus normal cardiac wall motion, CIM is able to add to the analysis a quantitative regional EF for each given segment. As a semi-automated tool, CIM has the potential to reduce reviewer variability and decrease the time required for analysis. In the future, CIM can potentially quantitatively track global and regional changes in patients with heart disease and aid the clinical management throughout the course of the disease.

Renal transplant: nonenhanced renal MR angiography with magnetization-prepared steady-state free precession.

The institutional review board approved this HIPAA-compliant study and waived informed consent. The purpose was to investigate nonenhanced magnetic resonance (MR) angiography with steady-state free precession (SSFP) with inversion recovery for assessing renal arteries in patients with renal transplants. Thirteen recipients of renal transplants underwent SSFP MR angiography before contrast material-enhanced MR angiography. Three stenoses (two mild, one severe) were identified at SSFP MR angiography in agreement with findings at contrast-enhanced MR angiography. There was no significant difference in image quality between the two methods. Results suggest SSFP MR angiography permits image quality of renal transplant arteries and detection of arterial stenosis comparable with those at contrast-enhanced MR angiography.

Pulmonary vein imaging with unenhanced three-dimensional balanced steady-state free precession MR angiography: initial clinical evaluation.

PURPOSE: To determine whether unenhanced magnetic resonance (MR) angiography performed with a three-dimensional (3D) segmented steady-state free precession (SSFP) sequence would be an alternative to contrast material-enhanced MR angiography for evaluating pulmonary veins (PVs) prior to and following radiofrequency (RF) ablation for atrial fibrillation. MATERIALS AND METHODS: MR angiographic examinations of PVs, performed in 20 patients (nine men, 11 women; mean age, 56.4 years +/- 12.7 [standard deviation]), were retrospectively reviewed according to an institutional review board-approved protocol. The number of PVs and their orthogonal measurements obtained from the 3D SSFP images were compared with those obtained from contrast-enhanced MR angiography. Signal-to-noise and contrast-to-noise ratios were also compared. Qualitative assessment of both techniques was performed by independent reviewers who scored the image quality (on a scale of 1 to 5) on the basis of PV conspicuity. The presence of cardiac and extracardiac pathologic indicators was also determined. Bland-Altman and Wilcoxon signed rank statistical analyses were performed. RESULTS: The mean difference in PV diameter measurements between contrast-enhanced MR angiography and 3D SSFP was -0.02 cm +/- 0.25. Signal-to-noise and contrast-to-noise ratios were higher for 3D SSFP images than for contrast-enhanced MR angiograms. Qualitatively, there was no significant difference in PV conspicuity between the techniques. Noncardiac pathologic indicators were detected in 10 of 20 patients on 3D SSFP images but not on contrast-enhanced MR angiograms. CONCLUSION: Unenhanced PV MR angiography performed by using a free-breathing 3D SSFP technique is as accurate as contrast-enhanced MR angiography for measuring PV diameter. This technique can be used for patients in whom contrast-enhanced computed tomographic or MR angiography is contraindicated and may be sufficient in all patients.

Multiecho dixon fat and water separation method for detecting fibrofatty infiltration in the myocardium.

Conventional approaches for fat and water discrimination based on chemical-shift fat suppression have reduced ability to characterize fatty infiltration due to poor contrast of microscopic fat. The multiecho Dixon approach to water and fat separation has advantages over chemical-shift fat suppression: 1) water and fat images can be acquired in a single breathhold, avoiding misregistration; 2) fat has positive contrast; 3) the method is compatible with precontrast and late-enhancement imaging, 4) less susceptible to partial-volume effects, and 5) robust in the presence of background field variation; and 6) for the bandwidth implemented, chemical-shift artifact is decreased. The proposed technique was applied successfully in all 28 patients studied. This included 10 studies with indication of coronary artery disease (CAD), of which four cases with chronic myocardial infarction (MI) exhibited fatty infiltration; 13 studies to rule out arrhythmogenic right ventricular cardiomyopathy (ARVC), of which there were three cases with fibrofatty infiltration and two confirmed with ARVC; and five cases of cardiac masses (two lipomas). The precontrast contrast-to-noise ratio (CNR) of intramyocardial fat was greatly improved, by 240% relative to conventional fat suppression. For the parameters implemented, the signal-to-noise ratio (SNR) was decreased by 30% relative to conventional late enhancement. The multiecho Dixon method for fat and water separation provides a sensitive means of detecting intramyocardial fat with positive signal contrast.

A dual-projection respiratory self-gating technique for whole-heart coronary MRA.

PURPOSE: To investigate the accuracy of a dual-projection respiratory self-gating (DP-RSG) technique in dynamic heart position measurement and its feasibility for free-breathing whole-heart coronary MR angiography (MRA). MATERIALS AND METHODS: A DP-RSG method is proposed to enable accurate direct measurement of heart position by acquiring two whole-heart projections. On 14 volunteers we quantitatively evaluated the efficacy of DP-RSG by comparison with diaphragmatic navigator (NAV) and single-projection-based respiratory self-gating (SP-RSG) methods. For DP-RSG we also compared center-of-mass and two profile-matching algorithms in deriving heart motion. Coronary imaging was conducted on eight volunteers based on retrospective gating to preliminarily validate the effectiveness of DP-RSG for whole-heart coronary MRA. Comparison of vessel delineation was performed between images reconstructed using different gating methods. RESULTS: The quantitative evaluation shows that DP-RSG more accurately tracks heart motion than NAV with all gating window (GW) values and SP-RSG approaches with GW>or=2.5 mm and profile-matching algorithms are more reliable for motion derivation than center-of-mass calculations with GW>or=1.0 mm. Whole-heart coronary MRA studies demonstrate the feasibility of using DP-RSG to improve overall delineation of the coronary arteries. CONCLUSION: DP-RSG is a promising approach to better resolve respiratory motion for whole-heart coronary MRA compared to conventional NAV and SP-RSG.