Detection and quantification of valvular heart disease with dynamic cardiac MR imaging

Congenital pulmonary malformations

There are many congenital anomalies of the lung, some of which have no clinical symptoms and are detected incidentally, while others, particularly in the neonatal and infant period, are recognized by their typical signs, symptoms, and radiological appearance. Some congenital lung anomalies are so important that they can cause the death of the patient if not diagnosed and treated early. Classification of congenital lung anomalies is difficult since these anomalies may be related to the airway, arterial and venous vascular system, pulmonary parenchyma, and primitive anterior intestinal anomalies from which the lung originates, and some anomalies may have several etiologic origins. In this review, all subgroups of congenital pulmonary malformations will be discussed.

Pulmonary arteries: imaging of pulmonary embolism and beyond

The pulmonary arteries are not just affected by thrombus. Various acquired and congenital conditions can also affect the pulmonary arteries. In this review we discuss cross sectional imaging modalities utilized for the imaging of the pulmonary arteries. Acquired pulmonary artery entities, including pulmonary artery sarcoma (PAS), vasculitis, aneurysm, and arteriovenous malformations, and congenital anomalies in adults, including proximal interruption of the pulmonary artery, pulmonary sling, pulmonary artery stenosis, and idiopathic dilatation of the pulmonary trunk, are also discussed. An awareness of these entities and their imaging findings is important for radiologists interpreting chest imaging.

Aortic regurgitation assessment by cardiovascular magnetic resonance imaging and transthoracic echocardiography: intermodality disagreement impacting on prediction of post-surgical left ventricular remodeling

Transthoracic echocardiography (TTE) is the primary clinical imaging modality for the assessment of patients with isolated aortic regurgitation (AR) in whom TTE's linear left ventricular (LV) dimension is used to assess disease severity to guide aortic valve replacement (AVR), yet TTE is relatively limited with regards to its integrated semi-quantitative/qualitative approach. We therefore compared TTE and cardiovascular magnetic resonance (CMR) assessment of isolated AR and investigated each modality's ability to predict LV remodeling after AVR. AR severity grading by CMR and TTE were compared in 101 consecutive patients referred for CMR assessment of chronic AR. LV end-diastolic diameter and end-systolic diameter measurements by both modalities were compared. Twenty-four patients subsequently had isolated AVR. The pre-AVR estimates of regurgitation severity by CMR and TTE were correlated with favorable post-AVR LV remodeling. AR severity grade agreement between CMR and TTE was moderate (ρ = 0.317, P = 0.001). TTE underestimated CMR LV end-diastolic and LV end-systolic diameter by 6.6 mm (P < 0.001, CI 5.8-7.7) and 5.9 mm (P < 0.001, CI 4.1-7.6), respectively. The correlation of post-AVR LV remodeling with CMR AR grade (ρ = 0.578, P = 0.004) and AR volumes (R = 0.664, P < 0.001) was stronger in comparison to TTE (ρ = 0.511, P = 0.011; R = 0.318, P = 0.2). In chronic AR, CMR provides more prognostic relevant information than TTE in assessing AR severity. CMR should be considered in the management of chronic AR patients being considered for AVR.

Motion-robust cardiac B1+ mapping at 3T using interleaved bloch-siegert shifts

PURPOSE

To develop and evaluate a robust motion-insensitive Bloch-Siegert shift based B1+ mapping method in the heart.

METHODS

Cardiac Bloch-Siegert B1+ mapping was performed with interleaved positive and negative off-resonance shifts and diastolic spoiled gradient echo imaging in 12 heartbeats. Numerical simulations were performed to study the impact of respiratory motion. The method was compared with three-dimensional (3D) actual flip angle imaging (AFI) and two-dimensional (2D) saturated double angle method (SDAM) in phantom scans. Cardiac B1+ maps of three different views were acquired in six healthy volunteers using Bloch-Siegert and SDAM during breath-hold and free breathing. In vivo maps were evaluated for inter-view consistency using the correlation coefficients of the B1+ profiles along the lines of intersection between the views.

RESULTS

For the Bloch-Siegert sequence, numerical simulations indicated high similarity between breath-hold and free breathing scans, and phantom results indicated low deviation from the 3D AFI reference (normalized root mean square error [NRMSE] = 2.0%). Increased deviation was observed with 2D SDAM (NRMSE = 5.0%) due to underestimation caused by imperfect excitation slice profiles. Breath-hold and free breathing Bloch-Siegert in vivo B1+ maps were visually comparable with no significant difference in the inter-view consistency (P > 0.36). SDAM showed strongly impaired B1+ map quality during free breathing. Inter-view consistency was significantly lower than with the Bloch-Siegert method (breath-hold: P = 0.014, free breathing: P < 0.0001).

CONCLUSION

The proposed interleaved Bloch-Siegert sequence enables cardiac B1+ mapping with improved inter-view consistency and high resilience to respiratory motion. Magn Reson Med 78:670-677, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Cardiovascular Magnetic Resonance Imaging-Incremental Value in a Series of 361 Patients Demonstrating Cost Savings and Clinical Benefits: An Outcome-Based Study

BACKGROUND

This study was designed to assess the clinical impact and cost-benefit of cardiovascular magnetic resonance imaging (CMR). In the face of current health care cost concerns, cardiac imaging modalities have come under focused review. Data related to CMR clinical impact and cost-benefit are lacking.

METHODS AND RESULTS

Retrospective review of 361 consecutive patients (pts) who underwent CMR exams was conducted. Indications for CMR were tabulated for appropriateness criteria. Components of the CMR exam were identified along with evidence of clinical impact. The cost of each CMR exam was ascertained along with cost savings attributable to the CMR exam for calculation of an incremental cost-effectiveness ratio. A total of 354 of 361 pts (98%) had diagnostic quality studies. Of the 361 pts, 350 (97%) had at least 1 published Appropriateness Criterion for CMR. A significant clinical impact attributable to CMR exam results was observed in 256 of 361 pts (71%). The CMR exam resulted in a new diagnosis in 69 of 361 (27%) pts. Cardiovascular magnetic resonance imaging results avoided invasive procedures in 38 (11%) pts and prevented additional diagnostic testing in 26 (7%) pts. Comparison of health care savings using CMR as opposed to current standards of care showed a net cost savings of $833 037, ie, per patient cost savings of $2308.

CONCLUSIONS

Cardiovascular magnetic resonance imaging provides diagnostic image quality in >98% of cases. Cardiovascular magnetic resonance imaging findings have documentable clinical impact on patient management in 71% of pts undergoing the exam, in a cost beneficial manner.

Cardiac MR Imaging in the Evaluation of Rheumatic Valvular Heart Diseases

INTRODUCTION

Rheumatic heart disease is the most common cause of valvular heart disease throughout the world. Echocardiography is the dominant imaging investigation in the assessment of cardiac valvular disease and the role of Magnetic Resonance Imaging (MRI) is so far limited. However, due to rapid improvements in the cardiac MRI technology in past few years, this non invasive technique is gaining interest in the examination of cardiac valves.

AIM

Our study was undertaken to define the role of MRI in the evaluation of Rheumatic valvular heart disease and to compare the role of MRI with transthoracic echocardiography with regard to quantity of stenosis and volume regurgitation.

MATERIALS AND METHODS

ECG gated Cardiac MRI was performed with a 1.5-Tesla system (MAGNETOM SYMPHONY- Model 2005) using basic cardiac software (Argus viewer) by a phased-array multicoil on 50 subjects who were known cases of Rheumatic valvular heart disease. A chest radiograph and echocardiography were done in all patients before MR examination. Informed consent was taken from all patients.

RESULTS

Mitral stenosis either as an isolated valvular abnormality or in combination with other valvular abnormalities constituted the major bulk of Rheumatic valvular heart disease in our study population. The average ejection fraction by ECHO is 64.94±7.11 and by MRI 67.52±7.84. The average mitral valve area by ECHO is 1.79±0.43 cm(2) and by MRI 1.82±0.47 cm(2). The average aortic valve area by ECHO is 1.10±0.21 cm(2) and by MRI 1.12±0.25 cm(2). The Coefficient of Correlation (r) is 0.82 for ejection fraction, 0.98 for mitral valve area and 0.92 for aortic valve area which means a strong positive association between the results by ECHO and MRI. In all instances, the p-value is <0.00001, suggesting that the test is highly significant.

CONCLUSION

In our study echocardiography was found to be the gold standard for the diagnosis of Rheumatic valvular heart disease and the role of MRI remained only complimentary to Echocardiography. However with advanced cardiac software, more advanced techniques, and faster imaging sequences, MRI may become a valuable procedure for investigation and follow-up of patients with valvular heart disease.

Quantitation of mitral regurgitation after percutaneous MitraClip repair: comparison of Doppler echocardiography and cardiac magnetic resonance imaging

OBJECTIVE

Percutaneous valve intervention for severe mitral regurgitation (MR) using the MitraClip is a novel technology. Quantitative assessment of residual MR by transthoracic echocardiography (TTE) is challenging, with multiple eccentric jets and artifact from the clips. Cardiovascular magnetic resonance (CMR) is the reference standard for left and right ventricular volumetric assessment. CMR phase-contrast flow imaging has superior reproducibility for quantitation of MR compared to echocardiography. The objective of this study was to establish the feasibility and reproducibility of CMR in quantitating residual MR after MitraClip insertion in a prospective study.

METHODS

Twenty-five patients underwent successful MitraClip insertion. Nine were excluded due to non-magnetic resonance imaging (MRI) compatible implants or arrhythmia, leaving 16 who underwent a comprehensive CMR examination at 1.5 T (Siemens Aera) with multiplanar steady state free precession (SSFP) cine imaging (cine CMR), and phase-contrast flow acquisitions (flow CMR) at the mitral annulus atrial to the MitraClip, and the proximal aorta. Same-day echocardiography was performed with two-dimensional (2D) visualization and Doppler. CMR and echocardiographic data were independently and blindly analyzed by expert readers. Inter-rater comparison was made by concordance correlation coefficient (CCC) with 95% confidence intervals (CIs), and Bland-Altman (BA) methods.

RESULTS

Mean age was 79 years, and mean LVEF was 44%±11% by CMR and 54%±16% by echocardiography. Inter-observer reproducibility of echocardiographic visual categorical grading by expert readers was poor, with a CCC of 0.475 (-0.7, 0.74). Echocardiographic Doppler regurgitant fraction reproducibility was modest (CCC 0.59, 0.15-0.84; BA mean difference -3.7%, -38% to 31%). CMR regurgitant fraction reproducibility was excellent (CCC 0.95, 0.86-0.98; BA mean difference -2.4%, -11.9 to 7.0), with a lower mean difference and narrower limits of agreement compared to echocardiography. Categorical severity grading by CMR using published ranges had good inter-observer agreement (CCC 0.86, 0.62-0.95).

CONCLUSIONS

CMR performs very well in the quantitation of MR after MitraClip insertion, with excellent reproducibility compared to echocardiographic methods. CMR is a useful technique for the comprehensive evaluation of residual regurgitation in patients after MitraClip. Technical limitations exist for both techniques, and quantitation remains a challenge in some patients.

Effect of papillary muscles and trabeculae on left ventricular measurement using cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy

Objective

To evaluate the influence of papillary muscles and trabeculae on left ventricular (LV) cardiovascular magnetic resonance (CMR) analysis using three methods of cavity delineation (classic or modified inclusion methods, and the exclusion method) in patients with hypertrophic cardiomyopathy (HCM).

Materials and Methods

This retrospective study included 20 consecutive HCM patients who underwent 1.5-T CMR imaging with short-axis cine stacks of the entire LV. LV measurements were performed using three different methods of manual cavity delineation of the endocardial and epicardial contours: method A, presumed endocardial boundary as seen on short-axis cine images; method B, including solely the cavity and closely adjacent trabeculae; or method C, excluding papillary muscles and trabeculae. Ascending aorta forward flow was measured as reference for LV-stroke volume (SV). Interobserver reproducibility was assessed using intraclass correlation coefficients.

Results

Method A showed larger end-diastole and end-systole volumes (largest percentage differences of 25% and 68%, respectively, p < 0.05), compared with method C. The ejection fraction was 55.7 ± 6.9% for method A, 68.6 ± 8.4% for B, and 71.7 ± 7.0% for C (p < 0.001). Mean mass was also significantly different: 164.6 ± 47.4 g for A, 176.5 ± 50.5 g for B, and 199.6 ± 53.2 g for C (p < 0.001). LV-SV error was largest with method B (p < 0.001). No difference in interobserver agreement was observed (p > 0.05).

Conclusion

In HCM patients, LV measurements are strikingly different dependent on whether papillary muscles and trabeculae are included or excluded. Therefore, a consistent method of LV cavity delineation may be crucial during longitudinal follow-up to avoid misinterpretation and erroneous clinical decision-making.

Assessment of pulmonary arterial pressure by velocity-encoded cine magnetic resonance imaging in children with congenital heart disease

BACKGROUND

Velocity-encoded cine magnetic resonance imaging (VEC-MRI) has recently been reported as effective for assessing not only pulmonary blood flow (Qp) but also pulmonary arterial pressure (PAP) in adults. However, there have been few reports on the usefulness of VEC-MRI for assessing PAP in children with congenital heart disease (CHD).

METHODS AND RESULTS

We evaluated 34 children with CHD. Qp and systemic blood flows (Qs) were determined by cardiac catheterization and VEC-MRI. The right-to-left Qp ratio (R/L) was measured by pulmonary perfusion scintigraphy and VEC-MRI. The pulmonary-to-systemic blood pressure ratio (Pp/Ps) was determined by cardiac catheterization. The acceleration time (AcT), ejection time (ET), peak velocity (PV), acceleration volume (AcV), and maximal change in flow rate during ejection (MCFR) in the pulmonary arteries, which were standardized by body surface area, were determined by VEC-MRI. The children were divided into 2 groups according to Pp/Ps. The Qs, R/L ratio and Qp/Qs obtained by VEC-MRI strongly correlated with those obtained by catheterization and scintigraphy. No significant differences in AcT, ET, AcT/ET, PV, or AcV were observed between the 2 groups. However, a significant difference was observed in MCFR. Furthermore, a significant correlation was observed between the MCFR and Pp/Ps.

CONCLUSIONS

This study clearly demonstrated that VEC-MRI is useful for assessing not only blood flow, but also PAP, by referring to MCFR in children.

Apicoaortic conduit and cerebral perfusion in mixed aortic valve disease: a computational analysis

OBJECTIVES

The revival of the apicoaortic conduit has attracted new interest in this alternative treatment for severe aortic stenosis unsuitable for conventional valve replacement. However, doubts still exist about the perfusion of the epiaortic vessels after apicoaortic conduit implantation, especially when severe aortic stenosis is associated with aortic valve insufficiency. The aim of the study was to evaluate the perfusion of the epiaortic vessels (innominate artery, left carotid artery and left subclavian artery) in cases of mixed aortic valve disease before and after apicoaortic conduit implantation.

METHODS

Starting from the data of a real patient with severe aortic stenosis and mild aortic insufficiency who underwent apicoaortic conduit implantation, we created a computational model where severe aortic valve stenosis was associated with different grades of aortic insufficiency (mild, medium and moderate).

RESULTS

A total of six combinations were analysed. In all simulations, the more severe the concomitant aortic insufficiency, the more the flow through the epiaortic vessels was diminished. After apicoaortic conduit implantation, there was an absolute augmentation of the median output in each epiaortic vessel compared with the same combination of mixed aortic valve disease before implantation. Interestingly, retrograde flow from the conduit in the descending aorta was minimal and did not contribute to the improved output of the epiaortic vessels.

CONCLUSIONS

The computational analysis suggested a protective effect, rather than steal phenomenon, of the apicoaortic conduit towards the cerebral perfusion, even in cases of mixed aortic valve disease.

CT and MR imaging of the aortic valve: radiologic-pathologic correlation

Valvular disease is estimated to account for as many as 20% of cardiac surgical procedures performed in the United States. It may be congenital in origin or secondary to another disease process. One congenital anomaly, bicuspid aortic valve, is associated with increased incidence of stenosis, regurgitation, endocarditis, and aneurysmal dilatation of the aorta. A bicuspid valve has two cusps instead of the normal three; resultant fusion or poor excursion of the valve leaflets may lead to aortic stenosis, the presence of which is signaled by dephasing jets on magnetic resonance (MR) images. Surgery is generally recommended for patients with severe stenosis who are symptomatic or who have significant ventricular dysfunction; transcatheter aortic valve implantation (TAVI) is an emerging therapeutic option for patients who are not eligible for surgical treatment. Computed tomography (CT) is an essential component of preoperative planning for TAVI; it is used to determine the aortic root dimensions, severity of peripheral vascular disease, and status of the coronary arteries. Aortic regurgitation, which is caused by incompetent closure of the aortic valve, likewise leads to the appearance of jets on MR images. The severity of regurgitation is graded on the basis of valvular morphologic parameters; qualitative assessment of dephasing jets at Doppler ultrasonography; or measurements of the regurgitant fraction, volume, and orifice area. Mild regurgitation is managed conservatively, whereas severe or symptomatic regurgitation usually leads to valve replacement surgery, especially in the presence of substantial left ventricular enlargement or dysfunction. Bacterial endocarditis, although less common than aortic stenosis and regurgitation, is associated with substantial morbidity and mortality. Electrocardiographically gated CT reliably demonstrates infectious vegetations and benign excrescences of 1 cm or more on the valve surface, allowing the assessment of any embolic complications.

[Clinical indications for the use of cardiac MRI. By the SIRM Study Group on Cardiac Imaging]

Cardiac magnetic resonance (CMR) is considered an useful method in the evaluation of many cardiac disorders. Based on our experience and available literature, we wrote a document as a guiding tool in the clinical use of CMR. Synthetically we describe different cardiac disorders and express for each one a classification, I to IV, depending on the significance of diagnostic information expected.

Evaluation of the aortic and mitral valves with cardiac computed tomography and cardiac magnetic resonance imaging

Cardiac computed tomography (CT) produces high-quality anatomical images of the cardiac valves and associated structures. Cardiac magnetic resonance imaging (MRI) provides images of valve morphology, and allows quantitative evaluation of valvular dysfunction and determination of the impact of valvular lesions on cardiovascular structures. Recent studies have demonstrated that cardiac CT and MRI are important adjuncts to echocardiography for the evaluation of aortic and mitral valvular heart diseases (VHDs). Radiologists should be aware of the technical aspects of cardiac CT and MRI that allow comprehensive assessment of aortic and mitral VHDs, as well as the typical imaging features of common and important aortic and mitral VHDs on cardiac CT and MRI.

Phase-contrast MRI and applications in congenital heart disease

A review of phase-contrast magnetic resonance imaging techniques, with specific application to congenital heart disease, is presented. Theory, pitfalls, advantages, and specific examples of multiple, well-described congenital heart disease presentations are discussed.

Diagnostic approach to assessment of valvular heart disease using MRI-Part I: a practical approach for valvular regurgitation

Valvular heart diseases from any cause are divided into two categories: stenosis and regurgitation. Acquired knowledge of the pathological aetiology and disease severity are the important clues for optimal treatment, which may be medication or combination with surgery. The non-invasive techniques have been established for valvular heart disease evaluation for many years especially in demonstrating valvular structure and assessing severity. Transthoracic echocardiography still plays the major role. However, not every case can be clearly evaluated by transthoracic echocardiography because of rib space window limitation. In the present-day practice, MRI has been extensively used for the evaluation of heart diseases in both unique and complementary categories. However, valvular heart disease assessment using cardiac MRI still remains an important challenge.

CT and MR imaging of the mitral valve: radiologic-pathologic correlation

Computed tomography (CT) and magnetic resonance (MR) imaging are increasingly important adjuncts to echocardiography for the evaluation of mitral valve disease. The mitral valve may be involved in various acquired or congenital conditions with resultant regurgitation or stenosis, and many of these conditions can be identified with CT or MR imaging. In addition, CT is useful for detecting and monitoring postoperative complications after mitral valve repair or replacement. As the use of CT and MR imaging increases, awareness of the CT and MR imaging appearances of the normal mitral valve and the various disease processes that affect it may foster recognition of unsuspected mitral disease in patients undergoing imaging for other purposes. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.306105518/-/DC1.

Computed tomography evaluation of cardiac valves: a review

Electrocardiograph (ECG)-gated cardiac computed tomography (CT) angiography has great potential for the evaluation of the cardiac valves, with excellent image quality. The evidence-based, established clinical role of ECG-gated CT coronary angiography provides additional valuable information about valve morphology and function. A wide range of valve pathology, including congenital and acquired conditions, infectious endocarditis, and complications of valve replacement, can be assessed by cardiac CT imaging. Despite recent advances in CT technology, echocardiography remains the gold standard for noninvasive cardiac valve evaluation. Nevertheless, important clinical information about the valves can be obtained with coronary CT angiography examinations. Thus cardiac valve morphology and function should be routinely assessed and reported on coronary CT angiography examinations.

Flow assessment through four heart valves simultaneously using 3-dimensional 3-directional velocity-encoded magnetic resonance imaging with retrospective valve tracking in healthy volunteers and patients with valvular regurgitation

OBJECTIVES

To validate 3-dimensional (3D) 3-directional velocity-encoded (VE) magnetic resonance imaging (MRI) for flow assessment through all 4 heart valves simultaneously with retrospective valve-tracking during off-line analysis in healthy volunteers and in patients with valvular regurgitation.

MATERIAL AND METHODS

Three-dimensional 3-directional VE MRI was performed in 22 healthy volunteers and in 29 patients with ischemic cardiomyopathy who were suspected of valvular regurgitation and net flow volumes through the 4 heart valves were compared. Furthermore, the analysis was repeated for each valve in 10 healthy volunteers and in 10 regurgitant valves to assess intra- and interobserver agreement for assessment of respectively net flow volumes and regurgitation fraction.

RESULTS

In healthy volunteers, the average net flow volume through the mitral valve, tricuspid valve, aortic valve, and pulmonary valve was 85 +/- 20 mL, 85 +/- 21 mL, 83 +/- 19 mL, 82 +/- 21 mL, respectively. Strong correlations between net flow volumes through the 4 heart valves were observed (intraclass correlation coefficients [ICC] 0.93-0.95) and the coefficient of variance (CV) was small (6%-9%). The repeated analysis by the same observer and by a second observer yielded good agreement for measurement of net flow volumes (ICC: 0.93-0.99 and CV: 3%-7%). Strong correlations between the net flow volumes through the 4 heart valves were also observed in the patients with valvular regurgitation (ICC: 0.85-0.95 and CV: 7%-18%). The average net flow volume through the mitral valve, tricuspid valve, aortic valve, and pulmonary valve was 63 +/- 20 mL, 63 +/- 20 mL, 63 +/- 20 mL, 63 +/- 20 mL, respectively. Furthermore, the intra- and interobserver agreement for assessment of regurgitation fraction was good (ICC: 0.86 and 0.85, CV: 12% and 13%).

CONCLUSIONS

Flow assessment using 3D 3-directional VE MR with retrospective valve-tracking during off-line analysis enables accurate quantification of net flow volumes through 4 heart valves within a single acquisition in healthy volunteers and in patients with valvular regurgitation.

Clinical significance of papillary muscle late enhancement detected via cardiac magnetic resonance imaging in patients with single old myocardial infarction

BACKGROUND

Contrast-enhanced cardiac magnetic resonance imaging (MRI) can depict papillary muscle (PM) necrosis or fibrosis by late enhancement (LE) of PM, but its clinical significance in old myocardial infarction (OMI) has been little understood.

METHODS

Myocardial LE and PM-LE were detected with contrast imaging in 60 patients with OMI caused by a single culprit coronary artery lesion. Left ventricular (LV) morphology and function, mitral valve geometry, and severity of mitral regurgitation were also evaluated by cine imaging. Sphericity index was calculated for the assessment of LV remodeling.

RESULTS

PM-LE was detected in 32 of 60 (53.3%) OMI patients. Unilateral PM-LE was detected in 22 patients and bilateral PM-LE in 10 patients. Patients with bilateral PM-LE demonstrated more severe LV remodeling and functional mitral regurgitation than those with unilateral or no PM-LE (sphericity index; bilateral PM-LE, 1.60±0.15, unilateral PM-LE, 1.71±0.29, no PM-LE, 1.85±0.27, p≤0.05) (mitral regurgitation; bilateral PM-LE, 1.10±0.57, unilateral PM-LE, 0.41±0.73, no PM-LE, 0.54±0.84, p≤0.05). In cases of unilateral PM-LE, posteromedial PM-LE resulting from right coronary artery-related OMI was accompanied by less severe mitral regurgitation, while anterolateral PM-LE resulting from left coronary artery-related OMI was not associated with severity of mitral regurgitation.

CONCLUSIONS

More than half of patients with OMI showed unilateral or bilateral PM-LE, and bilateral PM-LE was closely related to more severe LV remodeling and functional mitral regurgitation.

Optimization of MR phase-contrast-based flow velocimetry and shear stress measurements

This study was designed to measure the pixel-by-pixel flow velocity and shear stress from phase-contrast MR images. An optimized method was suggested and the use of the method was confirmed. A self-developed, straight steady flow model system was scanned by MRI with a velocity-encoded phase-contrast sequence. In-house developed software was used for the pixel-by-pixel flow velocity and shear stress measurements and the measurements were compared with physically measured mean velocity and shear stress. A comparison between the use of the in-house velocimetry software and a commercial velocimetry system was also performed. Curved steady flow models were scanned by phase-contrast MRI. Subsequently, velocity and shear stress were measured to confirm the shifted peak flow velocity and shear stress toward the outer side of the lumen. Peak velocity and shear stress were calculated for both the inner and outer half of the lumen and were statistically compared. The mean velocity measured with the use of in-house software had a significant correlation with the physical measurements of mean velocity; in addition, the measurement was more precise compared to the commercial system (R(2) = 0.85 vs. 0.75, respectively). The calculated mean shear stress had a significant correlation with the physical measurements of mean shear stress (R(2) = 0.95). The curved flow model showed a significantly shifted peak velocity and shear stress zones toward the outside of the flow (P < 0.0001). The technique to measure pixel-by-pixel velocity and shear stress of steady flow from velocity-encoded phase-contrast MRI was optimized. This technique had a good correlation with physical measurements and was superior to a commercially available system.

CT angiography of the cardiac valves: normal, diseased, and postoperative appearances

Although echocardiography remains the principal imaging technique for assessment of the cardiac valves, contrast material-enhanced electrocardiographically gated computed tomographic (CT) angiography is proving to be an increasingly valuable complementary modality in this setting. CT angiography allows excellent visualization of the morphologic features and function of the normal valves, as well as of a wide range of valve diseases, including congenital and acquired diseases, infectious endocarditis, and complications of valve replacement. The number, thickness, and opening and closing of the valve leaflets, as well as the presence of valve calcification, can be directly observed. CT angiography also permits simultaneous assessment of the valves and coronary arteries, which may prove valuable in presurgical planning. Unlike echocardiography and magnetic resonance imaging, however, CT angiography requires ionizing radiation and does not provide a direct measure of the valvular pressure gradient. Nevertheless, with further development of related imaging techniques, CT angiography can be expected to play an increasingly important role in the evaluation of the cardiac valves. Supplemental material available at http://radiographics.rsna.org/cgi/content/full/29/5/1393/DC1.

Cardiovascular applications of phase-contrast MRI

OBJECTIVE

The purpose of this study was to review and illustrate various clinical applications of phase-contrast MRI.

CONCLUSION

Cardiac MRI has emerged as a valuable noninvasive clinical tool for evaluation of the cardiovascular system. Phase-contrast MRI has a variety of established applications in quantifying blood flow and velocity and several emerging applications, such as evaluation of diastolic function and myocardial dyssynchrony.

Juvenile and adult congenital heart disease: time-resolved 3D contrast-enhanced MR angiography

PURPOSE

To assess the incremental diagnostic value of time-resolved three-dimensional (3D) magnetic resonance (MR) angiography over single-phase 3D MR angiography and cine MR imaging in juvenile and adult patients with congenital heart disease (CHD).

MATERIALS AND METHODS

The study was HIPAA compliant and was approved by the institutional review board. Written informed consent was obtained from each patient. Eighty-one consecutive patients (46 male and 35 female patients; mean age, 31.1 years +/- 13.5 [standard deviation]) with CHD were examined with a 1.5-T MR imaging unit. The imaging protocol comprised time-resolved MR angiography (repetition time msec/echo time msec, 2.01/0.81) after injection of 0.03 mmol gadodiamide per kilogram of body weight at 4 mL/sec and single-phase high-spatial-resolution MR angiography (2.87/0.97) after injection of 0.15 mmol/kg gadodiamide at 1.5 mL/sec. After review of the time-resolved and conventional MR angiographic data sets, each of two independent observers listed the additional clinical information gained from time-resolved MR angiographic data. A Wilcoxon signed rank test was used to test for statistical differences between the image quality ratings of the two observers.

RESULTS

Time-resolved and single-phase high-spatial-resolution MR angiography yielded diagnostic image data in all patients. Observers 1 and 2 found functional information in time-resolved MR angiographic series in 52 and 51 patients, respectively, that was not seen at high-spatial-resolution MR angiography. Intra- and extracardiac shunts, respectively, were exclusively depicted by time-resolved MR angiography for observer 1 in 18 and two patients and for observer 2 in 15 and two patients. However, both observers reported higher confidence in the assessment of such smaller vascular structures as supraaortic vessels (in 12 patients for observer 1 and 11 patients for observer 2) and major aortopulmonary collateral arteries (in eight patients for observer 1 and 10 patients for observer 2) at high-spatial-resolution MR angiography. No significant difference was evident in image quality scoring between the two observers (P = .32 for time-resolved and P = .47 for conventional MR angiography).

CONCLUSION

Compared with conventional MR angiography, time-resolved MR angiography yields clinically relevant information in a substantial number of patients; hence, the two techniques should be regarded as complementary.

Current and upcoming roles of CT and MRI in clinical cardiac imagery

Cardiovascular CT and MRI are rapidly emerging technologies that can potentially change the current paradigm of cardiovascular imaging. Cardiac CT is primarily focused on imaging of coronary arteries for the assessment of vessel wall plaque and lumen stenosis. Additional information about ventricular and valvular function can also be obtained from the same three-dimensional image dataset. Cardiovascular magnetic resonance is a versatile imaging modality now considered a reference standard in the evaluation of ventricular morphology and function, with the potential to achieve a similar status in perfusion and viability assessment. This review summarizes key concepts regarding CT and MRI technology, clinical applications, and their role in clinical decision making. Recently published appropriateness criteria for cardiac CT and MRI by the American College of Cardiology are also reviewed.

Assessment of blood flow and valvular heart disease using phase-contrast cardiovascular magnetic resonance

Measurement of blood flow is important for assessing the severity of disease processes involving the cardiovascular system. Phase-contrast cardiovascular magnetic resonance (PC-CMR) can be used to measure blood flow noninvasively without ionizing radiation or limitations imposed by body habitus. This review describes the performance of PC-CMR and its clinical utility in assessing patients with cardiovascular or valvular heart disease.

Evaluation of aortic regurgitation in congenital heart disease: value of MR imaging in comparison to echocardiography

BACKGROUND

Evaluation of the severity and the follow-up of aortic insufficiency (AI) are important tasks in paediatric cardiology. Assessment is based on clinical and echocardiographic (ECHO) findings such as the configuration of the valve and the regurgitation fraction (RF).

OBJECTIVE

The goal of this study was to evaluate MRI compared to ECHO for determination of clinical severity, valve morphology and RF.

MATERIALS AND METHODS

Thirty patients (age 3-27 years) with mild-to-severe AI were evaluated by clinical examination, ECHO (2-D and Doppler), and MRI at 1.5 T (2-D true-FISP cine short axis, phase-contrast flow in the ascending aorta).

RESULTS

Both methods identified 13 bicuspid and 17 tricuspid valves. Good correlations between ECHO and cine MRI were found for ventricular mass, stroke volume, and ejection fraction. A good linear correlation was found for the RF determined by ECHO and phase-contrast MRI (r = 0.7). The RF was 6% in mild AI, 17% in moderate AI, and 30% in severe AI. The different severity groups showed significantly different RF and it was possible to discriminate between clinical severity grades (P = 0.01).

CONCLUSION

ECHO and MRI showed good agreement in evaluating morphology and function of the left ventricle. The clinical severity of the disease can be evaluated correctly using MRI.

Relevante Nebenbefunde in der Magnetresonanztomographie des Herzens am Beispiel eines Bronchialkarzinoms und eines malignen Lymphoms

BACKGROUND

Here we consider the prevalence of extracardiac findings in the standard sequences and planning surveys of cardiac MRI.

PATIENTS AND METHODS

Over a period of 2 years, 363 patients (261 men, 102 women) with different clinical diagnoses were examined by cardiac MRI. The MRI protocol included a planning survey in three planes and standard sequences in long and short axis orientation.

RESULTS

A total of 53 extracardiac findings were detected: 1 lymphoma, 1 bronchogenic carcinoma, 1 retroperitoneal hematoma, 1 mediastinal lymphadenopathy, 1 tumor of the adrenal glad, 16 pleural effusions, 14 renal cysts, 12 liver cysts, 2 pulmonary infiltrate, 1 atelectasis, 2 cholecystolithiasis, 1 diaphragmatic elevation, 1 hiatus hernia.

CONCLUSION

Evaluation of the standard sequences and the planning surveys is useful for discovering extracardiac findings in a cardiac MRI and should be carried out routinely.

ACR Practice Guideline for the Performance and Interpretation of Cardiac Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is an established imaging modality, recognized for its value in the assessment and monitoring of a wide range of cardiac pathology. It can provide physiologic as well as anatomic information. Image interpretation requires both well-developed MRI skills and knowledge of cardiac pathology. Radiologists, because of their extensive experience in MRI, have an important role in its application in the heart. The guidelines presented here are an educational tool designed to assist practitioners in providing the best possible patient care via the diagnostic methods of cardiac MRI. American College of Radiology requirements for physicians and personnel performing and interpreting cardiac MRI, which will become applicable by July 1, 2008, are also presented.

Cardiac magnetic resonance in outpatients in Germany—indications, complications and protocol suggestions from a high-volume center

BACKGROUND

Cardiac magnetic resonance (CMR) has developed into a routine examination in many centers in cardiology. However, there is little knowledge about its applicability in outpatients as a diagnostic tool for cardiovascular diseases. We report about the experiences in a high-volume cardiac imaging center and in a "mobile setting" in Germany and provide routinely used examination protocols.

METHODS

8976 patients referred for CMR from cardiologists, internal medicine practices and from general practitioners and 2200 patients examined in a "mobile" system by outpatient cardiologists were included in the study. Indications were as follows: 7672 (69%) examinations for myocardial ischemia and viability, 1313 (12%) for cardiac and pericardial inflammatory disease and cardiac mass, 976 (9%) for detection and quantification of heart valve disease and 466 (4%) for congenital heart disease. 697 (6%) were referred for other indication. Two independent readers performed image analysis of the 8976 patients in our center.

RESULTS

Image quality was rated "excellent" in 90.6%, "good" in 8%, "fair" in 1.2% and "poor" in 0.2%. 0.0002% of all examinations were not assessable due to low image quality. Minor complications (temporarily, asymptomatic AV-blockade; mild chest pain and/or dyspnea; nausea) could be observed in 12% and resolved within few minutes. One patient experienced a grand mal seizure due to hyperventilation. 0.9% examinations had to be terminated untimely due to claustrophobia.

CONCLUSION

CMR in outpatients is a widely used imaging modality in cardiology in Germany. A large variety of clinical questions may be answered by CMR with excellent image quality and without major complication. With user-adapted protocols, a rapid diagnosis is achieved even in outpatients in a "mobile" setting. Hence, CMR will increase its applicability as a routine imaging tool.

Three-dimensional contrast-enhanced MR angiography of the thoraco-abdominal vessels

With the strategies presented in this article,relevant disease involving the thoraco-abdominal vessels can be well depicted by 3D CEMRA. Aneurysms, dissections, occlusions, congenital lesions, and anatomic anomalies are readily assessed. Time-resolved MRA provides supplemental information in shunts, dissections, aneurysms, and AVMs. Velocity-encoded imaging may help fur-ther characterize lesions and may provide useful functional information to grade and monitor the progression of stenotic disease. 3.0T imaging and recent development in multicoil RF technology will further improve the performance of 3D CEMRAin terms of temporal and spatial resolution.

Applications of phase-contrast flow and velocity imaging in cardiovascular MRI

A review of cardiovascular clinical and research applications of MRI phase-contrast velocity imaging, also known as velocity mapping or flow imaging. Phase-contrast basic principles, advantages, limitations, common pitfalls and artefacts are described. It can measure many different aspects of the complicated blood flow in the heart and vessels: volume flow (cardiac output, shunt, valve regurgitation), peak blood velocity (for stenosis), patterns and timings of velocity waveforms and flow distributions within heart chambers (abnormal ventricular function) and vessels (pulse-wave velocity, vessel wall disease). The review includes phase-contrast applications in cardiac function, heart valves, congenital heart diseases, major blood vessels, coronary arteries and myocardial wall velocity.

How to plan and perform a cardiac MR imaging examination

Because of the enormous economic and social impact of cardiovascular disease in the United States there is a need for improved noninvasive diagnosis. Cardiac MR imaging isa versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology and MR imaging physical principles,cardiac MR imaging can be performed and can play an important role in patient management. This article provides the reader with a basic understanding of cardiac MR imaging and the practical applications required to perform cardiac MR imaging.

Cine MR imaging of heart valve dysfunction with segmented true fast imaging with steady state free precession

PURPOSE

To evaluate the value of cine true fast imaging with steady-state free precession (SSFP) for semiquantitative assessment of valvular dysfunction in the heart and to compare the results to that obtained with a standard breath-hold segmented gradient-recalled echo-planar imaging sequence (GE-EPI).

MATERIALS AND METHODS

Twenty-three patients with known valvular dysfunction (main component: 16 with aortic valve stenosis, nine with aortic valve insufficiency, three with mitral stenosis, two with mitral regurgitation, two with tricuspidal regurgitation, and one with pulmonary stenosis) and 23 control subjects with normal valvular function underwent MR imaging on a 1.5-T system (ACS-NT, Philips, Best, The Netherlands). Cine SSFP and GE-EPI images were acquired in identical long-axis views. Images were evaluated for the presence and extent of the signal void arising from the valves and for image quality consensus by two experienced radiologists. Results were compared to those obtained by cardiac catheterization (in 16 patients) or color Doppler (in the remaining seven patients).

RESULTS

On SSPF images, the complex flow pattern in valvular regurgitant or stenotic lesions caused signal void within the bright blood pool of the atria or ventricles, similar to GE-EPI, in all patients. Valvular dysfunction was delineated using SSFP with the same high sensitivity (100%) as using the GE-EPI sequence. Results correlated to those obtained by cardiac catheterization or color Doppler ultrasonography (P < 0.001, r = 0.97). However, the jet phenomenon was slightly more pronounced in five patients on GE-EPI. There was no significant signal void in the 23 control subjects with both sequences. In all 46 subjects, the image quality of SSFP images was rated higher (P < 0.05; 2.6 +/- 0.1; using a scale ranging from 0-3) compared to GE-EPI (1.7 +/- 0.1).

CONCLUSION

The results of this study suggest that valvular dysfunction can be semiquantitatively assessed using SSFP cine MR imaging.

Magnetic resonance imaging of primary cardiomyopathies

Cardiomyopathies are diseases of the myocardium of unknown etiology associated with cardiac dysfunction. On the grounds of their morphology and pathophysiology, primary or idiopathic cardiomyopathies may be classified into a number of disorders; namely, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, and restrictive cardiomyopathy. The term "secondary cardiomyopathies" is reserved to specific heart muscle diseases clinically very similar to primary cardiomyopathies. Cardiac magnetic resonance imaging has long been used to study cardiac morphology and, more recently, to assess blood flow, perfusion, and contractile function. The emerging role of magnetic resonance imaging for the understanding and treatment of primary cardiomyopathies cannot be underestimated. From a clinical point of view, an examination based on a single, efficient, and noninvasive MR study focusing on the clinically relevant features of cardiomyopathies is an objective and reproducible means for diagnosing and monitoring hypertrophic, arrhythmogenic, dilated, and restrictive cardiomyopathies.

Performing cardiac MR imaging: an overview

Because of the enormous economic and social impact of cardiovascular disease in the United States, there is a need for improved noninvasive diagnosis. Cardiac MR imaging is a versatile, comprehensive technique for assessing cardiac morphology and function. With an understanding of cardiac anatomy and physiology as well as MR physical principles, cardiac MR imaging can be performed and play an important role in patient management.