Cine Balanced Steady-state Free Precession Research Articles

Non-invasive assessment of cardiac function and pulmonary vascular resistance in an canine model of acute thromboembolic pulmonary hypertension using 4D flow cardiovascular magnetic resonance.

BackgroundThe purpose of this study was to quantify right (RV) and left (LV) ventricular function, pulmonary artery flow (QP), tricuspid valve regurgitation velocity (TRV), and aorta flow (QS) from a single 4D flow cardiovascular magnetic resonance (CMR) (time-resolved three-directionally motion encoded CMR) sequence in a canine model of acute thromboembolic pulmonary hypertension (PH).MethodsAcute PH was induced in six female beagles by microbead injection into the right atrium. Pulmonary arterial (PAP) and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) were measured by right heart catheterization (RHC) at baseline and following induction of acute PH. Pulmonary vascular resistance (PVRRHC) was calculated from RHC values of PAP, PCWP and CO (PVRRHC = (PAP-PCWP)/CO). Cardiac magnetic resonance (CMR) was performed on a 3 T scanner at baseline and following induction of acute PH. RV and LV end-diastolic (EDV) and end-systolic (ESV) volumes were determined from both CINE balanced steady-state free precession (bSSFP) and 4D flow CMR magnitude images. QP, TRV, and QS were determined from manually placed cutplanes in the 4D flow CMR flow-sensitive images in the main (MPA), right (RPA), and left (LPA) pulmonary arteries, the tricuspid valve (TRV), and aorta respectively. MPA, RPA, and LPA flow was also measured using two-dimensional flow-sensitive (2D flow) CMR.ResultsBiases between 4D flow CMR and bSSFP were 0.8 mL and 1.6 mL for RV EDV and RV ESV, respectively, and 0.8 mL and 4 mL for LV EDV and LV ESV, respectively. Flow in the MPA, RPA, and LPA did not change after induction of acute PAH (p = 0.42-0.81). MPA, RPA, and LPA flow determined with 4D flow CMR was significantly lower than with 2D flow (p < 0.05). The correlation between QP/TRV and PVRRHC was 0.95. The average QP/QS was 0.96 ± 0.11.ConclusionsUsing both magnitude and flow-sensitive data from a single 4D flow CMR acquisition permits simultaneous quantification of cardiac function and cardiopulmonary hemodynamic parameters important in the assessment of PH.

Biventricular strain analysis at 1.5T cardiac MR imaging: preliminary results in volunteers using an iterative SENSE reconstruction with L1 regularization

Background Changes in myocardial strain have been shown to precede onset of systolic dysfunction in patients with cardiomyopathy. Traditionally performed with echocardiography, acoustic windows can limit strain evaluation. Preliminary work has shown good agreement between myocardial strain derived from deformation field analysis at balanced steady-state free-precession (bSSFP) cine MRI and speckle tracking echocardiography. The application of a novel prototype iterative SENSE reconstruction with L1 regularization (IRSENSE) to highly accelerated segmented bSSFP cine acquisitions can maintain or improve the effective temporal resolution with a shorter breath-hold. The purpose of this study is to evaluate left- and right-ventricular stain analysis from bSSFP cine acquisitions using conventional GRAPPA and highly accelerated T-PAT with IR-SENSE. We hypothesize that myocardial strain parameters derived from accelerated T-PAT cine acquisitions with IR-SENSE are similar to those obtained using conventional segmented bSSFP with comparable effective temporal resolutions.

Segmented CMR acquisition with iterative SENSE reconstruction using L1-regularization in the evaluation of right ventricular systolic function

Background Cardiac MR (CMR) has emerged as the gold standard in assessing biventricular size and systolic function with segmented balanced steady-state free-precession (bSSFP) cine acquisitions. The application of a novel prototype iterative reconstruction technique to sparsely undersampled segmented bSSFP cine acquisitions may enable higher acceleration factors while shortening image acquisitions, thus maintaining adequate image quality for quantitative analysis. The purpose of this study is to evaluate the clinical utility of a segmented sparsely sampled 2D CINE imaging technique, with a prototype iterative SENSE reconstruction using L1-regularization, in the quantitative assessment of right ventricular (RV) systolic function.

Cine MR Enterography Grading of Small Bowel Peristalsis: Evaluation of the Antiperistaltic Effectiveness of Sublingual Hyoscyamine Sulfate

To use a cine balanced steady-state free precession magnetic resonance enterography (cine MRE) pulse sequence to assess the effectiveness of a sublingual (SL) antiperistaltic agent, hyoscyamine sulfate. Institutional review board approval was granted with an exemption for informed consent in this Health Insurance Portability and Accountability Act-compliant, retrospective, single-institution study. Of the 288MRE examinations performed between October 1, 2007 and January 15, 2011, 92 using SL hyoscyamine sulfate for antiperistalsis were included for review, each with cine MRE before and after medication. These 184 cine MRE data sets were randomized, blinded for treatment, and independently reviewed by five attending abdominal radiologists, who rated the degree of whole abdomen bowel motility on each cine MRE data set on a 5-point scale. Pre- and postmedication mean peristalsis ratings, standard deviation, mean difference, and treatment effect sizes werecalculated. A repeated measures analysis of variance test was performed using a significance threshold of P=.05. Interobserver reliabilities were also calculated. Mean peristalsis ratings ranged 2.63-3.34 and 2.36-3.03, before and after medication administration, respectively. The mean differences ranged from 0.22 to 0.46, which are treatment effect sizes of 0.20 to 0.37. The decrease in peristalsis observed by the five reviewing radiologists after SL hyoscyamine sulfate administration was significant (df = 1/182, f=7.35, P<.01). The interobserver reliabilities were 0.34 for the pretest and 0.33 for the posttest. Although cine MRE sequences show decreased bowel peristalsis after the use of SL hyoscyamine sulfate, the small size ofthe observed treatment effect is likely insufficient to justify its use for MRE.

Quantification of Thoracic Blood Flow Using Volumetric Magnetic Resonance Imaging With Radial Velocity Encoding

The objective of this study was to validate radially undersampled 5-point velocity-encoded time-resolved flow-sensitive magnetic resonance imaging (MRI) ("PC-VIPR", phase contrast vastly undersampled imaging with isotropic resolution projection reconstruction magnetic resonance) for the quantification of ascending aortic (AAO) and main pulmonary artery (MPA) flow in vivo. Data from 18 healthy volunteers (41.6 ± 16.2 years [range, 22-73 years]; body mass index, 26.0 ± 3.5 [19.1-31.4]) scanned at 3 T with a 32-channel coil were included. The left and right ventricular stroke volumes calculated from contiguous short-axis CINE-balanced steady state free precession (CINE-bSSFP) slices were used as the primary reference for cardiac output. Flow measured from 2-dimensional phase contrast MRI (2D-PC-MRI) in the AAO and the MPA served as the secondary reference. Time-resolved 4-dimensional flow-sensitive MRI (4D flow MRI) using PC-VIPR was performed with a velocity sensitivity of Venc = 150 cm/s reconstructed to 20 time frames at 1.4-mm isotropic spatial resolution. In 11 of 20 volunteers, phantom-corrected 4D flow MRI data were also assessed. Differences between methods of calculating the left ventricular and right ventricular cardiac output were assessed with the Bland-Altman analysis (BA, mean difference ±2SD). The QP/QS-ratio was calculated for each method. Initially, PC-VIPR compared unfavorably with CINE-bSSFP (left ventricular stroke volume: 96.5 ± 14.4 mL; right ventricular stroke volume: 93.6 ± 14.0 mL vs 81.2 ± 24.3 mL [AAO] and 85.6 ± 25.4 mL [MPA]; P = 0.027 and 0.25) with BA differences of -14.6 ± 44.0 mL (AAO) and -9.0 ± 45.9 mL (MPA). Whereas phantom correction had minor effects on 2D-PC-MRI results and comparison with CINE-bSSFP, it improved PC-VIPR results: BA differences between CINE-bSSFP and PC-VIPR after correction were -1.4 ± 15.3 mL (AAO) and -4.1 ± 16.1 mL (MPA); BA comparison with 2D-PC-MRI improved to -12.0 ± 48.1 mL (AAO) and -2.2 ± 19.5 mL (MPA). QP/QS-ratio results for all techniques were within physiologic limits. Accurate quantification of AAO and MPA flows with radially undersampled 4D flow MRI applying 5-point velocity encoding is achievable when phantom correction is used.

Which cardiovascular magnetic resonance planes and sequences provide accurate measurements of branch pulmonary artery size in children with right ventricular outflow tract obstruction?

Children with right ventricular outflow tract obstructive (RVOTO) lesions require precise quantification of pulmonary artery (PA) size for proper management of branch PA stenosis. We aimed to determine which cardiovascular magnetic resonance (CMR) sequences and planes correlated best with cardiac catheterization and surgical measurements of branch PA size. Fifty-five children with RVOTO lesions and biventricular circulation underwent CMR prior to; either cardiac catheterization (n = 30) or surgery (n = 25) within a 6 month time frame. CMR sequences included axial black blood, axial, coronal oblique and sagittal oblique cine balanced steady-state free precession (bSSFP), and contrast-enhanced magnetic resonance angiography (MRA) with multiplanar reformatting in axial, coronal oblique, sagittal oblique, and cross-sectional planes. Maximal branch PA and stenosis (if present) diameter were measured. Comparisons of PA size on CMR were made to reference methods: (1) catheterization measurements performed in the anteroposterior plane at maximal expansion, and (2) surgical measurement obtained from a maximal diameter sound which could pass through the lumen. The mean differences (Δ) and intra class correlation (ICC) were used to determine agreement between different modalities. CMR branch PA measurements were compared to the corresponding cardiac catheterization measurements in 30 children (7.6 ± 5.6 years). Reformatted MRA showed better agreement for branch PA measurement (ICC > 0.8) than black blood (ICC 0.4-0.6) and cine sequences (ICC 0.6-0.8). Coronal oblique MRA and maximal cross sectional MRA provided the best correlation of right PA (RPA) size with ICC of 0.9 (Δ -0.1 ± 2.1 mm and Δ 0.5 ± 2.1 mm). Maximal cross sectional MRA and sagittal oblique MRA provided the best correlate of left PA (LPA) size (Δ 0.1 ± 2.4 and Δ -0.7 ± 2.4 mm). For stenoses, the best correlations were from coronal oblique MRA of right pulmonary artery (RPA) (Δ -0.2 ± 0.8 mm, ICC 0.9) and sagittal oblique MRA of left pulmonary artery (LPA) (Δ 0.2 ± 1.1 mm, ICC 0.9). CMR PA measurements were compared to surgical measurements in 25 children (5.4 ± 4.8 years). All MRI sequences demonstrated good agreement (ICC > 0.8) with the best (ICC 0.9) from axial cine bSSFP for both RPA and LPA. Maximal cross sectional and angulated oblique reformatted MRA provide the best correlation to catheterization for measurement of branch PA's and stenosis diameter. This is likely due to similar angiographic methods based on reformatting techniques that transect the central axis of the arteries. Axial cine bSSFP CMR was the best surgically measured correlate of PA branch size due to this being a measure of stretched diameter. Knowledge of these differences provides more precise PA measurements and may aid catheter or surgical interventions for RVOTO lesions.

Water‐fat separation imaging of the heart with standard magnetic resonance bSSFP CINE imaging

To study balanced steady-state free precession CINE phase-sensitive water-fat separation imaging in four cardiac imaging planes to determine the necessary phase correction and image artifacts particular to this technique. Ten healthy volunteers and two subjects with known heart pathologies were studied with standard balanced steady-state free precession CINE imaging. Water-only and fat-only images were calculated using sign detection of the real part of the complex image after phase correction with constant and linear terms. Phase correction values were determined using both manual and automated methods. Differences in phase correction values between imaging planes, cardiac phases, coil elements, automated image reconstruction parameters as well as artifact scores between the automated and manual methods were studied with statistical tests. Water-fat separation performed well in the heart after constant and linear phase correction. Both constant (p = 0.8) and linear x (p = 1) and y (p = 1) phase correction values did not vary significantly across cardiac phases, but varied significantly among the coils (p < 0.001) and imaging planes (p < 0.001). False water-fat separation artifacts were most frequent in the chest/back and also were present at the mitral and aortic valves. Constant and linear phase correction is necessary to provide consistent results in standard imaging planes using a balanced steady-state free precession water-fat separation postprocessing algorithm applied to standard cardiac CINE imaging.

Hybrid PET/MR Imaging of the Heart: Feasibility and Initial Results

To assess the feasibility of hybrid imaging of the heart with fluorine 18 fluorodeoxyglucose (FDG) on an integrated 3-T positron emission tomography (PET)/magnetic resonance (MR) imaging system. The present study was approved by the local institutional review board. Written informed consent was obtained from all patients before imaging. Twenty consecutive patients with myocardial infarction (n = 20) underwent cardiac PET/MR imaging examination. Ten patients underwent additional cardiac PET/computed tomography (CT) before PET/MR. Two-dimensional half-Fourier acquisition single-shot turbo spin-echo sequences, balanced steady-state free precession cine sequences, two-dimensional turbo inversion-recovery magnitude T2-weighted sequences, and late gadolinium-enhanced (LGE) segmented two-dimensional inversion-recovery turbo fast low-angle shot sequences were performed. According to the 17-segment model, PET tracer uptake, wall motion, and late gadolinium enhancement were visually assessed for each segment on a binary scale, and categorical intermethod agreement was calculated by using the Cohen κ. The maximum standardized uptake value was measured in corresponding myocardial locations on PET/CT and PET/MR images. Agreement was substantial over all patients and segments between PET and LGE images (κ = 0.76) and between PET and cine images (κ = 0.78). In 306 segments, 97 (32%) were rated as infarcted on PET images, compared with 93 (30%) rated as infarcted on LGE images and with 90 (29%) rated as infarcted on cine images. In a subgroup of patients (n = 10) with an additional PET/CT scan, no significant difference in myocardial tracer uptake between PET/CT and PET/MR images was found (paired t test, P = .95). Cardiac PET/MR imaging with FDG is feasible and may add complementary information in patients with ischemic heart disease.

Variable flip angle balanced steady‐state free precession for lower SAR or higher contrast cardiac cine imaging

Cardiac cine balanced steady-state free precession (bSSFP) imaging uses a high flip angle (FA) to obtain high blood-myocardium signal-to-noise and contrast-to-noise ratios (CNR). Use of high FAs, however, results in substantially increased SAR. Our objective was to develop a variable FA bSSFP cardiac cine imaging technique with: (1) low SAR and blood-myocardium CNR similar to conventional constant FA bSSFP (CFA-bSSFP) or (2) increased blood-myocardium CNR compared to CFA-bSSFP with similar SAR. Variable FA bSSFP cardiac cine imaging was achieved using an asynchronous k-space acquisition, which is asynchronous to the cardiac cycle (aVFA-bSSFP). Bloch simulations and phantom experiments were performed to compare the signal, resolution, and frequency response of the variable FA bSSFP and CFA-bSSFP schemes. Ten volunteers were imaged with different aVFA-bSSFP and asynchronous CFA-bSSFP schemes and compared to conventional segmented CFA-bSSFP. The SAR of aVFA-bSSFP is significantly decreased by 36% compared to asynchronous CFA-bSSFP (1.9 ± 0.2 vs. 3.0 ± 0.2 W/kg, P < 10(-10)) for similar blood-myocardium CNR (34 ± 6 vs. 35 ± 9, P = 0.5). Alternately, the CNR of the aVFA-bSSFP is improved by 28% compared to asynchronous CFA-bSSFP (49 ± 9 vs. 38 ± 8, P < 10(-4)) with similar SAR (3.2 ± 0.5 vs. 3.3 ± 0.5 W/kg, P = 0.6). aVFA-bSSFP can be used for lower SAR or higher contrast cardiac cine imaging compared to the conventional segmented CFA-bSSFP imaging.

CINE BALANCED STEADY-STATE FREE PRECESSION IS A RELIABLE ALTERNATIVE TO CONVENTIONAL T2-WEIGHTED IMAGING AND EVANS BLUE FOR THE CMR ASSESSMENT OF AREA AT RISK AFTER MYOCARDIAL INFARCTION

Non-invasive assessment of the area at risk (AAR) during myocardial infarction (MI) is of paramount importance in cardioprotection studies. Current cardiac magnetic resonance (CMR) methods require 2 separate scans for assessment of cardiac function (cine balanced steady-state free precession

Monitoring and compensating phase imperfections in cine balanced steady‐state free precession

To analyze and correct for eddy current-induced phase imperfections in cardiac cine balanced steady-state free precession (bSSFP) imaging. Eddy current-induced phase offsets were measured for different phase-encoding schemes using a higher order dynamic field camera. Based on these measurements, offset phases were corrected for in postprocessing and by run-time phase compensation applying radiofrequency phase increments and additional compensatory gradient areas. The findings were validated using numerical simulations, phantom experiments, and in vivo cardiac scans. Depending on the phase-encoding scheme, significant eddy current-induced phase offsets were detected. Time-varying phase offsets were observed at subsequent excitations leading to steady-state distortions and hence to profile-dependent amplitude modulations in k-space. Taking into account measured k-space trajectories algebraic image reconstruction allowed compensating imperfect spatial encoding. Correction of amplitude modulations was successfully accomplished by run-time phase compensation. Using magnetic field monitoring, artifacts in cine balanced steady-state free precession caused by uncompensated eddy current fields can be significantly reduced.

Comparison of myocardial tagging and feature tracking in patients with severe aortic stenosis

Transcatheter aortic valve implantation (TAVI) has become an effective treatment for severe aortic stenosis (AS) in patients considered to be at high surgical risk. However, data relating to myocardial function and deformation in these patients are rare. Cardiovascular magnetic resonance (CMR) tagging has been established as non-invasive technique for the accurate measurement of myocardial motion. However, additional tagging datasets are necessary and the post-processing procedure is time-consuming. Recently, the novel technique of feature tracking (FT) was introduced, with which myocardial strain can be derived directly from balanced steady-state free precession (bSSFP) cine sequences. The study aim was to compare tagging with FT in patients with high-grade AS and who had been considered for TAVI. Thirty patients with severe AS underwent cardiac magnetic resonance imaging at 1.5 T (Philips Achieva). A stack of serial short-axis slices was used to assess left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), and LV mass and function. TomTec 2D Cardiac Performance Analysis software was used to derive myocardial deformation parameters from three short-axis cine views (basal, medial and apical levels) using bSSFP. All patients also underwent myocardial tagging on identical short-axis views, and data acquired from FT and tagging were compared. The mean left ventricular ejection fraction (LVEF), LVEDV and LVESV (57 ± 14%, 158 ± 58 ml, and 74 ± 48 ml, respectively) were all normal. All patients demonstrated concentric hypertrophy of the left ventricle with an increased basal septal thickness (16 ± 3 mm), LV mass (126 ± 40 g) and indexed LV mass (68 ± 23 g/m2, papillary muscles excluded). Bland-Altman analysis revealed a reasonable agreement between basal and medial circumferential strain (cc), and a good correlation was observed between tagging and FT for the derived basal and medial cc (Pearson's correlation coefficient 0.83 for basal, 0.74 for medial). Basal rotation was impaired compared to previous studies in patients with AS, but medial and apical rotations were comparable. The apical peak diastolic rotation velocity was faster compared to earlier analyses. Rotation, peak systolic and end-diastolic rotation velocity did not demonstrate any correlation or acceptable agreement between FT and tagging. The inter-observer agreement as assessed by the intra- class correlation coefficient for FT showed good results for the cc (basal 0.94, medial 0.83, apical 0.75). To the present authors' knowledge, this is the first study to assess myocardial motion using tagging and FT in patients with AS prior to TAVI. A reasonable agreement was found for the basal and medial cc between both techniques. Estimated cc-values using FT were systematically higher than those with tagging, but this might have been due to the different techniques employed. Although FT is a promising method to assess cc, further studies including the evaluation of standard values--and investigations with different diseases are necessary.

Magnetic resonance imaging in valvular heart disease: Clinical application and current role for patient management

Noninvasive imaging provides important information on cardiac anatomy and function and is a key element in clinical management of valvular heart disease (VHD). Beside echocardiography, which is still considered the first-line modality for assessment of valvular anatomy and longitudinal evaluation of VHD, cardiovascular magnetic resonance (CMR) has evolved during the last two decades as an essential tool for evaluation of cardiac diseases. Today, CMR not only represents the reference standard for measuring cardiac volumes, function, and mass, but also enables accurate assessment of morphology and function of cardiac valves. It can play an important role in clinical decision-making for patients with VHD. This review addresses current applications and limitations of CMR imaging techniques that are used in VHD including cine-balanced steady-state free precession (b-SSFP), phase contrast MR (pcMR), gradient-recalled echo (GRE), and turbo-spin echo (TSE) sequences. Moreover, it describes their application for evaluation of valvular pathologies and gives an overview on the current role of valvular CMR in patient management.

Pulmonary arterial distensibility - 2D phase contrast vs 2D bSSFP

Summary Main pulmonary artery distensibility is a strong predictor of mortality in patients with pulmonary arterial hypertension. This study shows that either 2D PC or 2D bSSFP can be used to reliably non-invasively assess it by measuring MPA relative area change. Background The pulmonary circulation is a highly compliant system that generates little resistance to blood flow. However, in the presence of pulmonary arterial hypertension (PAH), blood pressure and vascular resistance in the pulmonary circulation are elevated. This leads to distension and stiffening of the main pulmonary artery (MPA) and vessel wall remodeling, which in itself may influence stiffness [1]. Proximal arterial distensibility is a parameter that depends mainly on the anatomy (geometry) of the vessel and can be estimated noninvasively with cross-sectional imaging techniques. In particular, the relative area change (RAC) of the MPA, which is inversely proportional to arterial stiffness, is a strong predictor of mortality in patients with PAH [2]. The purpose of this study was to compare two non-invasive magnetic resonance imaging (MRI) methods for quantification of MPA distensibility using an acute PAH dog model. Methods Six adult female beagles were anesthetized with isoflurane. MRI was performed prior to and following injection of micro-beads into the right atrium and ventricle to induce PAH, resulting 12 comparison studies. The presence of PAH was confirmed by right heart catheterization (RHC). All MR images were acquired on a 3T scanner (MR750, GE Healthcare, Waukesha, WI). Double-oblique images perpendicular to the direction of the flow in the MPA were obtained using ECG-triggered 2D CINE balanced steady-state free precession (bSSFP) and through-plane velocity-encoded 2D phase contrast (PC) at the same level [3]. PC and bSSFP images were segmented using dedicated cardiovascular analysis software (CV-Flow and and MASS-Analysis, respectively, Medis, Leiden, NL). Maximum and minimum MPA areas (Amax and Amin, respectively) were used to calculate RAC = (Amax-Amin)/Amax. Bland-Altman analysis was used to study the differences between PC and bSSFP to calculate Amax ,A min, and RAC. Student t-test was used to evaluate statistical significance of the differences between techniques in all three paramenters. Results The mean values for RAC, Amax and Amin were 36.38 ±7.86%, 241.98±71.62cm 2 , and 157.06±58.51cm 2 for PC, respectively and 31.14±6.95%, 220.88±62.76cm 2 ,a nd 155.34±58.38cm 2 for bSSFP, respectively (p=0.10, 0.45, and 0.94, respectively). The mean differences for RAC, Amax and Amin were -5.23±8.44%, -21.10±40.67cm 2 , -1.72±40.89cm 2 , respectively. Conclusions No statistically significant difference is present between PC and bSSFP for measuring RAC, Amax or Amin .T he differences between the two methods for measuring these parameters are small suggesting that either technique (PC or bSSFP) can be used to reliably non-invasively measure MPA distensibility. A benefit of using PC for measuring RAC is that it can also be used to quantify blood flow. Funding

CMR Imaging of Edema in Myocardial Infarction Using Cine Balanced Steady-State Free Precession

The aim of this study was to investigate the capabilities of balanced steady-state free precession (bSSFP) cardiac magnetic resonance imaging as a novel cine imaging approach for characterizing myocardial edema in animals and patients after reperfused myocardial infarction. Current cardiac magnetic resonance methods require 2 separate scans for assessment of myocardial edema and cardiac function. Mini-pigs (n = 13) with experimentally induced reperfused myocardial infarction and patients with reperfused ST-segment elevation myocardial infarction (n = 26) underwent cardiac magnetic resonance scans on days 2 to 4 post-reperfusion. Cine bSSFP, T2-weighted short TI inversion recovery (T2-STIR), and late gadolinium enhancement were performed at 1.5-T. Cine bSSFP and T2-STIR images were acquired with a body coil to mitigate surface coil bias. Signal, contrast, and the area of edema were compared. Additional patients (n = 10) were analyzed for the effect of microvascular obstruction on bSSFP. A receiver-operator characteristic analysis was performed to assess the accuracy of edema detection. An area of hyperintense bSSFP signal consistent with edema was observed in the infarction zone (contrast-to-noise ratio: 37 ± 13) in all animals and correlated well with the area of late gadolinium enhancement (R = 0.83, p < 0.01). In all patients, T2-STIR and bSSFP images showed regional hyperintensity in the infarction zone. Normalized contrast-to-noise ratios were not different between T2-STIR and bSSFP. On a slice basis, the volumes of hyperintensity on T2-STIR and bSSFP images correlated well (R = 0.86, p < 0.001), and their means were not different. When compared with T2-STIR, bSSFP was positive for edema in 25 of 26 patients (96% sensitivity) and was negative in all controls (100% specificity). All patients with microvascular obstruction showed a significant reduction of signal in the subendocardial infarction zone compared with infarcted epicardial tissue without microvascular obstruction (p < 0.05). Myocardial edema from ST-segment elevation myocardial infarction can be detected using cine bSSFP imaging with image contrast similar to T2-STIR. This new imaging approach allows evaluation of cardiac function and edema simultaneously, thereby reducing patient scan time and increasing efficiency. Further work is necessary to optimize edema contrast in bSSFP images.

Acute Myocarditis: Diagnostic Value of Contrast-Enhanced Cine Steady-State Free Precession MRI Sequences

MRI has become the primary tool for assessment of myocardial inflammation in patients with suspected acute myocarditis. Optimal diagnostic performance is achieved with late gadolinium-enhanced sequences, but cine balanced steady-state free precession (SSFP) MRI sequences are routinely used to evaluate cardiac function. Our aim was to prospectively assess the diagnostic value of unenhanced and contrast-enhanced cine SSFP MRI sequences in comparison with late gadolinium-enhanced sequences for imaging of patients with strong evidence of acute myocarditis. Eighteen patients with strong evidence of acute myocarditis underwent 1.5-T cardiac MRI. Unenhanced and contrast-enhanced cine SSFP images and late gadolinium-enhanced images were obtained. The images were analyzed both qualitatively and quantitatively. Data were analyzed with analysis of variance and the Bonferroni test or paired Student t test. Areas of high signal intensity were detected in 28% (5/18), 94% (17/18), and 89% (16/18) of patients on unenhanced cine, contrast-enhanced cine, and late gadolinium-enhanced images. In one patient, contrast-enhanced cine images revealed subepicardial areas of high signal intensity that were not visible on late gadolinium-enhanced images. The location and transmural nature of involved segments matched on contrast-enhanced cine and late gadolinium-enhanced images (both, r = 0.91, p < 0.0001). The contrast-to-noise ratio was significantly higher on contrast-enhanced cine images than on late gadolinium-enhanced images (p < 0.05). Contrast-enhanced cine MRI is a valuable tool for detection of lesions of acute myocarditis and should be recommended for routine clinical MRI.

Cyclic CINE‐balanced steady‐state free precession image intensity variations: Implications for the detection of myocardial edema

To evaluate the dependence of CINE-balanced steady-state free precession (bSSFP) image intensities on spatial location, cardiac phase, and disease state. Eight subjects with recent myocardial infarctions and eight age- and sex-matched normal volunteers were studied using CINE-bSSFP imaging to describe cyclic image intensity variations as a function of the cardiac cycle and to optimize and assess the ability of CINE-bSSFP imaging to depict myocardial edema. Signal intensities of the left ventricular (LV) bloodpool and myocardium were measured using region-of-interest analysis across the cardiac cycle. The magnitude and time course of the cyclic variations were evaluated. Mixed-model analysis of variance was used to examine the influence of physical location, cardiac phase, and presence of myocardial infarction. The LV bloodpool and myocardial CINE-bSSFP signal intensities varied significantly with spatial location, cardiac phase, and disease (P < 0.001). Cardiac phase had a significant effect on the signal intensities after adjustments for spatial location. The LV bloodpool signal decreased slowly during systole and rose sharply during LV filling. There were two distinct myocardial intensity peaks, one occurring at peak systole and the other at the end of the LV rapid inflow phase. Myocardial edema was seen as a hyperintense region. Image contrast with adjacent myocardium was the greatest at the end of systole. Detection of myocardial edema using the conventional CINE-bSSFP technique is feasible, but is complicated by normal cyclic changes in myocardial image intensities during the cardiac cycle.

Determination of right ventricular volume and function using multiple axially rotated MRI slices

The conventional magnetic resonance imaging (MRI) method for right ventricular (RV) volume and motion, using short-axis (SA) orientation, is limited by RV anatomy and shape. We suggest an orientation based on six slices rotated around the long axis of the RV, rotated long axis (RLA). Three phantoms were investigated in SA and RLA using cine balanced steady-state free precession MRI. Volumes were calculated based on segmentation and checked against true volumes. In 23 healthy male volunteers, we used six long-axis planes from the middle of the tricuspid valve to the RV apex, rotated in 30° increments. For comparison, short-axis slices were acquired. Imaging parameters were identical in both acquisitions. Right ventricular end-diastolic (EDV), end-systolic (ESV) and stroke volumes (SV) determined in the RLA 179.1 ± 29.3; 80.1 ± 17.1; 99.3 ± 16.9 ml and in the SA were 174.0 ± 21.1; 78.8 ± 13.6; 95.3 ± 14.5 ml with P-values for the difference from 0.17 to 0.64 (ns). Interobserver variability ranged between 3.2% and 6.6% and intraobserver variability between 2.8% and 6.8%. In SA views, consensus for the definition of the basal slice was necessary in 39% of the volunteers for whom the average volume change was 20% in ESV and 10% in EDV. The RLA method results in better visualization and definition of the RV inflow, outflow and apex. Accurate measurement of RV volumes for diagnosis and follow-up of cardiac diseases are enhanced by the RLA orientation, even though additional acquisition time is required.

Epicardial Lipomatous Hypertrophy Mimicking Pericardial Effusion

HomeCirculation: Cardiovascular ImagingVol. 4, No. 1Epicardial Lipomatous Hypertrophy Mimicking Pericardial Effusion Free AccessResearch ArticlePDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissionsDownload Articles + Supplements ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toSupplementary MaterialsFree AccessResearch ArticlePDF/EPUBEpicardial Lipomatous Hypertrophy Mimicking Pericardial EffusionCharacterization With Cardiovascular Magnetic Resonance Christopher A. Miller, MRCP and Matthias Schmitt, MD, PhD Christopher A. MillerChristopher A. Miller From the Cardiovascular Magnetic Resonance Unit, North West Regional Cardiac Centre, University Hospital of South Manchester, Manchester, United Kingdom. Search for more papers by this author and Matthias SchmittMatthias Schmitt From the Cardiovascular Magnetic Resonance Unit, North West Regional Cardiac Centre, University Hospital of South Manchester, Manchester, United Kingdom. Search for more papers by this author Originally published1 Jan 2011https://doi.org/10.1161/CIRCIMAGING.110.957498Circulation: Cardiovascular Imaging. 2011;4:77–78IntroductionA 62-year-old man with no history of cardiac disease was referred because of exertional dyspnea. His body mass index was elevated at 29 kg/m2, and a large cutaneous lipoma was present on his abdominal wall. Transthoracic echocardiography was performed and initially reported to demonstrate a moderate-sized global pericardial effusion (Figure 1 and Movies 1 and 2). Consideration was given to pericardiocentesis; however, subsequent review suggested that the appearances may have been due to pericardial thickening (Movie 3). Cardiovascular magnetic resonance (CMR) imaging was performed for clarification.Download figureDownload PowerPointFigure 1. Echocardiographic images. Parasternal long-axis (A) and short-axis (B) views showing the echolucent zone surrounding the heart that was mistaken for a pericardial effusion (asterisk, dashed line). LV indicates left ventricle; RV, right ventricle; LA, left atrium; and Ao, aorta.A thick layer of epicardial tissue, measuring up to 29 mm deep, was seen to surround the myocardium on balanced steady-state free precession (SSFP) cine images (Figure 2 and Movie 4). On both SSFP and half-Fourier single-shot fast spin-echo images, signal intensity was high, indeed identical to that from subcutaneous fat. Using a spatial modulation of magnetization sequence (“tagging”), the epicardial tissue appeared to be adherent to the myocardium (Movie 5). The interatrial septum was also markedly thickened (23 mm), with sparing of the fossa ovalis, and had the same high signal intensity (Figure 2C). Fast spin-echo images with a fat-saturation inversion recovery prepulse (which significantly reduces, or “nulls,” the signal from fat) confirmed the epicardial and interatrial septal tissue to be fat (Figure 3). A diagnosis of epicardial lipomatous hypertrophy with concomitant lipomatous hypertrophy of the interatrial septum was made. The pericardium itself was thin and of normal appearance, with no evidence of pericardial effusion; indeed, the contrast provided by the fat allowed for unusually good delineation of the pericardium, highlighting its cranial extension.Download figureDownload PowerPointFigure 2. Cardiovascular magnetic resonance SSFP images. Left ventricular outflow tract (A), short-axis (B), 4-chamber (C), and coronal (D) images showing extensive epicardial lipomatous hypertrophy (asterisk) and lipomatous hypertrophy of the interatrial septum (double dagger). The pericardium (arrows) has a normal appearance, and its cranial extension is particularly evident (D) due to the contrast provided by the fat. RA indicates right atrium; PA, pulmonary artery.Download figureDownload PowerPointFigure 3. Cardiovascular magnetic resonance fat saturation images. In the corresponding fat-saturation fast spin-echo 4-chamber (A, corresponding to Figure 2C) and coronal (B, corresponding to Figure 2D) views, the signal from the epicardial (asterisk) and atrial septal (double dagger) lipomatous hypertrophy is “nulled,” confirming its fatty composition.Cardiac lipomatosis is characterized by the accumulation of nonencapsulated mature adipose tissue caused by hyperplasia of lipocytes. The etiology is unknown, but it may be associated with obesity and advancing age.1 The most frequent manifestation is lipomatous hypertrophy of the interatrial septum. Massive epicardial lipomatous hypertrophy is less well documented. Although histologically benign, it has been reported to cause cardiac tamponade, requiring decompressive pericardiectomy.2 In the presented case, cine imaging demonstrated normal right heart and caval appearances, phase contrast imaging with velocity encoding demonstrated normal systemic venous inflow, and on real-time, free-breathing imaging, ventricular septal motion was seen to be normal, all of which suggested reassuring cardiac filling physiology.The case highlights the possibility of mistaking epicardial lipomatous hypertrophy for pericardial effusion on transthoracic echocardiography. The tissue characterization provided by CMR allowed the diagnosis to be made, avoiding the need for invasive investigation or unnecessary intervention. The functional data provided by CMR suggested that the epicardial lipomatous hypertrophy was not affecting cardiac function.DisclosuresNone.FootnotesThe online-only Data Supplement is available at http://circimaging.ahajournals.org/cgi/content/full/CIRCIMAGING.110.957498/DC1.Correspondence to Dr Christopher Miller, Cardiovascular Magnetic Resonance Unit, North West Regional Cardiac Centre, University Hospital of South Manchester, Southmoor Road, Wythenshawe, Manchester, UK. E-mail [email protected]org.uk

Improved 3‐Tesla cardiac cine imaging using wideband

Cine balanced steady-state free precession (SSFP) is the most widely used sequence for assessing cardiac ventricular function at 1.5 T because it provides high signal-to-noise ratio efficiency and strong contrast between myocardium and blood. At 3 T, the use of SSFP is limited by susceptibility-induced off-resonance, resulting in either banding artifacts or the need to use a short-sequence pulse repetition time that limits the readout duration and hence the achievable spatial resolution. In this work, we apply wideband SSFP, a variant of SSFP that uses two alternating pulse repetition times to establish a steady state with wider band spacing in its frequency response and overcome the key limitations of SSFP. Prospectively gated cine two-dimensional imaging with wideband SSFP is evaluated in healthy volunteers and compared to conventional balanced SSFP, using quantitative metrics and qualitative interpretation by experienced clinicians. We demonstrate that by trading off temporal resolution and signal-to-noise ratio efficiency, wideband SSFP mitigates banding artifacts and enables imaging with approximately 30% higher spatial resolution compared to conventional SSFP with the same effective band spacing.