Lymphatic pathway evaluation in congenital heart disease using 3D whole-heart balanced steady state free precession and T2-weighted cardiovascular magnetic resonance.

BACKGROUND: Due to passive blood flow in palliated single ventricle, central venous pressure increases chronically, ultimately impeding lymphatic drainage. Early visualization and treatment of these malformations is essential to reduce morbidity and mortality. Cardiovascular magnetic resonance (CMR) T2-weighted lymphangiography (T2w) is used for lymphatic assessment, but its low signal-to-noise ratio may result in incomplete visualization of thoracic duct pathway. 3D-balanced steady state free precession (3D-bSSFP) is commonly used to assess congenital cardiac disease anatomy. Here, we aimed to improve diagnostic imaging of thoracic duct pathway using 3D-bSSFP. METHODS: Patients underwent CMR during single ventricle or central lymphatic system assessment using T2w and 3D-bSSFP. T2w parameters included 3D-turbo spin echo (TSE), TE/TR = 600/2500 ms, resolution = 1 × 1 × 1.8 mm, respiratory triggering with bellows. 3D-bSSFP parameters included electrocardiogram triggering and diaphragm navigator, 1.6 mm isotropic resolution, TE/TR = 1.8/3.6 ms. Thoracic duct was identified independently in T2w and 3D-bSSFP images, tracked completely from cisterna chyli to its drainage site, and classified based on severity of lymphatic abnormalities. RESULTS: Forty-eight patients underwent CMR, 46 of whom were included in the study. Forty-five had congenital heart disease with single ventricle physiology. Median age at CMR was 4.3 year (range 0.9-35.1 year, IQR 2.4 year), and median weight was 14.4 kg (range, 7.9-112.9 kg, IQR 5.2 kg). Single ventricle with right dominant ventricle was noted in 31 patients. Thirty-eight patients (84%) were status post bidirectional Glenn and 7 (16%) were status post Fontan anastomosis. Thoracic duct visualization was achieved in 45 patients by T2w and 3D-bSSFP. Complete tracking to drainage site was attained in 11 patients (24%) by T2w vs 25 (54%) by 3D-bSSFP and in 28 (61%) by both. Classification of lymphatics was performed in 31 patients. CONCLUSION: Thoracic duct pathway can be visualized by 3D-bSSFP combined with T2w lymphangiography. Cardiac triggering and respiratory navigation likely help retain lymphatic signal in the retrocardiac area by 3D-bSSFP. Visualizing lymphatic system leaks is challenging on 3D-bSSFP images alone, but 3D-bSSFP offers good visualization of duct anatomy and landmark structures to help plan interventions. Together, these sequences can define abnormal lymphatic pathway following single ventricle palliative surgery, thus guiding lymphatic interventional procedures.

Retraining Convolutional Neural Networks for Specialized Cardiovascular Imaging Tasks: Lessons from Tetralogy of Fallot.

Ventricular contouring of cardiac magnetic resonance imaging is the gold standard for volumetric analysis for repaired tetralogy of Fallot (rTOF), but can be time-consuming and subject to variability. A convolutional neural network (CNN) ventricular contouring algorithm was developed to generate contours for mostly structural normal hearts. We aimed to improve this algorithm for use in rTOF and propose a more comprehensive method of evaluating algorithm performance. We evaluated the performance of a ventricular contouring CNN, that was trained on mostly structurally normal hearts, on rTOF patients. We then created an updated CNN by adding rTOF training cases and evaluated the new algorithm's performance generating contours for both the left and right ventricles (LV and RV) on new testing data. Algorithm performance was evaluated with spatial metrics (Dice Similarity Coefficient (DSC), Hausdorff distance, and average Hausdorff distance) and volumetric comparisons (e.g., differences in RV volumes). The original Mostly Structurally Normal (MSN) algorithm was better at contouring the LV than the RV in patients with rTOF. After retraining the algorithm, the new MSN + rTOF algorithm showed improvements for LV epicardial and RV endocardial contours on testing data to which it was naïve (N = 30; e.g., DSC 0.883 vs. 0.905 for LV epicardium at end diastole, p < 0.0001) and improvements in RV end-diastolic volumetrics (median %error 8.1 vs 11.4, p = 0.0022). Even with a small number of cases, CNN-based contouring for rTOF can be improved. This work should be extended to other forms of congenital heart disease with more extreme structural abnormalities. Aspects of this work have already been implemented in clinical practice, representing rapid clinical translation. The combined use of both spatial and volumetric comparisons yielded insights into algorithm errors.

Feasibility of 3D black-blood variable refocusing angle fast spin echo cardiovascular magnetic resonance for visualization of the whole heart and great vessels in congenital heart disease.

BACKGROUND: Volumetric black-blood cardiovascular magnetic resonance (CMR) has been hampered by long scan times and flow sensitivity. The purpose of this study was to assess the feasibility of black-blood, electrocardiogram (ECG)-triggered and respiratory-navigated 3D fast spin echo (3D FSE) for the visualization of the whole heart and great vessels. METHODS: The implemented 3D FSE technique used slice-selective excitation and non-selective refocusing pulses with variable flip angles to achieve constant echo signal for tissue with T1 (880 ms) and T2 (40 ms) similar to the vessel wall. Ten healthy subjects and 21 patients with congenital heart disease (CHD) underwent 3D FSE and conventional 3D balanced steady-state free precession (bSSFP). The sequences were compared in terms of ability to perform segmental assessment, local signal-to-noise ratio (SNRl) and local contrast-to-noise ratio (CNRl). RESULTS: In both healthy subjects and patients with CHD, 3D FSE showed superior pulmonary vein but inferior coronary artery origin visualisation compared to 3D bSFFP. However, in patients with CHD the combination of 3D bSSFP and 3D FSE whole-heart imaging improves the success rate of cardiac morphological diagnosis to 100% compared to either technique in isolation (3D FSE, 23.8% success rate, 3D bSSFP, 5% success rate). In the healthy subjects SNRl for 3D bSSFP was greater than for 3D FSE (30.1 ± 7.3 vs 20.9 ± 5.3; P = 0.002) whereas the CNRl was comparable (17.3 ± 5.6 vs 17.4 ± 4.9; P = 0.91) between the two scans. CONCLUSIONS: The feasibility of 3D FSE for whole-heart black-blood CMR imaging has been demonstrated. Due to their high success rate for segmental assessment, the combination of 3D bSSFP and 3D FSE may be an attractive alternative to gadolinium contrast enhanced morphological CMR in patients with CHD.

Dual-phase whole-heart imaging using image navigation in congenital heart disease.

BACKGROUND: Dual-phase 3-dimensional whole-heart acquisition allows simultaneous imaging during systole and diastole. Respiratory navigator gating and tracking of the diaphragm is used with limited accuracy. Prolonged scan time is common, and navigation often fails in patients with erratic breathing. Image-navigation (iNAV) tracks movement of the heart itself and is feasible in single phase whole heart imaging. To evaluate its diagnostic ability in congenital heart disease, we sought to apply iNAV to dual-phase sequencing. METHODS: Healthy volunteers and patients with congenital heart disease underwent dual-phase imaging using the conventional diaphragmatic-navigation (dNAV) and iNAV. Acquisition time was recorded and image quality assessed. Sharpness and length of the right coronary (RCA), left anterior descending (LAD), and circumflex (LCx) arteries were measured in both cardiac phases for both approaches. Qualitative and quantitative analyses were performed in a blinded and randomized fashion. RESULTS: In volunteers, there was no significant difference in vessel sharpness between approaches (p > 0.05). In patients, analysis showed equal vessel sharpness for LAD and RCA (p > 0.05). LCx sharpness was greater with dNAV (p < 0.05). Visualized length with iNAV was 0.5 ± 0.4 cm greater than that with dNAV for LCx in diastole (p < 0.05), 1.0 ± 0.3 cm greater than dNAV for LAD in diastole (p < 0.05), and 0.8 ± 0.7 cm greater than dNAV for RCA in systole (p < 0.05). Qualitative scores were similar between modalities (p = 0.71). Mean iNAV scan time was 5:18 ± 2:12 min shorter than mean dNAV scan time in volunteers (p = 0.0001) and 3:16 ± 1:12 min shorter in patients (p = 0.0001). CONCLUSIONS: Image quality of iNAV and dNAV was similar with better distal vessel visualization with iNAV. iNAV acquisition time was significantly shorter. Complete cardiac diagnosis was achieved. Shortened acquisition time will improve clinical applicability and patient comfort.

Influence of acquired obesity on coronary vessel wall late gadolinium enhancement in discordant monozygote twins.

OBJECTIVES: The aim of this study was to investigate the impact of BMI on late gadolinium enhancement (LGE) of the coronary artery wall in identical monozygous twins discordant for BMI. Coronary LGE represents a useful parameter for the detection and quantification of atherosclerotic coronary vessel wall disease. METHODS: Thirteen monozygote female twin pairs (n = 26) with significantly different BMIs (>1.6 kg/m2) were recruited out of >10,000 twin pairs (TwinsUK Registry). A coronary 3D-T2prep-TFE MR angiogram and 3D-IR-TFE vessel wall scan were performed prior to and following the administration of 0.2 mmol/kg of Gd-DTPA on a 1.5 T MR scanner. The number of enhancing coronary segments and contrast to noise ratios (CNRs) of the coronary wall were quantified. RESULTS: An increase in BMI was associated with an increased number of enhancing coronary segments (5.3 ± 1.5 vs. 3.5 ± 1.6, p < 0.0001) and increased coronary wall enhancement (6.1 ± 1.1 vs. 4.8 ± 0.9, p = 0.0027) compared to matched twins with lower BMI. CONCLUSIONS: This study in monozygous twins indicates that acquired factors predisposing to obesity, including lifestyle and environmental factors, result in increased LGE of the coronary arteries, potentially reflecting an increase in coronary atherosclerosis in this female study population. KEY POINTS: • BMI-discordant twins allow the investigation of the influence of lifestyle factors independent from genetic confounders. • Only thirteen obesity-discordant twins were identified underlining the strong genetic component of BMI. • In female twins, a BMI increase is associated with increased coronary late gadolinium enhancement. • Increased late gadolinium enhancement in the coronary vessel wall potentially reflects increased atherosclerosis.

Whole-heart coronary MR angiography using image-based navigation for the detection of coronary anomalies in adult patients with congenital heart disease.

BACKGROUND: The purpose of this study was to evaluate a recently developed two-dimensional (2D) image-based navigation approach (iNAVG+C ) combined with respiratory bellows gating for CMRA in patients with congenital heart disease. METHODS: Nine healthy volunteers (mean age 32 ± 6 years [standard deviation]) and 29 patients (28 ± 9 years) were scanned on a 1.5 Tesla clinical scanner using iNAV(G+C) motion compensated T2prepared CMRA, and the conventional 1D NAV approach. Scan time was recorded for each CMRA scan. An image quality score was given to each coronary artery from (0, uninterpretable; to 4, excellent image quality). Additionally, vessel sharpness of each coronary artery was measured. RESULTS: Average scan time was significantly shorter (P < 0.01) using the proposed iNAVC+G approach (7:57 ± 1:34) compared with 1D NAV (9:15 ± 3:02). Improved visual scores of the right coronary artery (iNAV(G+C) : 4,3,4 (median, 25th percentile, 75th percentile) versus 1D NAV: 3,3,4; P < 0.001) and left anterior descending artery (iNAV(G+C) : 3,3,4 versus 1D NAV: 3,2,3; P < 0.001) were obtained using iNAV(G+C) compared with 1D NAV as well as an increased vessel sharpness of the right coronary artery (iNAV(G+C) : 65.3% ± 6.6% (mean ± standard deviation) versus 1D NAV: 60.2% ± 11.4%; P < 0.05) and left anterior descending artery (iNAV(G+C) : 63.2% ± 6.7% versus 1D NAV: 58.3% ± 9.5%; P < 0.05). CONCLUSION: Image-based navigation in combination with respiratory bellows gating allows for more robust suppression of respiratory motion artifacts for whole-heart CMRA compared with conventional 1D NAV as images can be acquired in a shorter time and with improved image quality.

A clinical combined gadobutrol bolus and slow infusion protocol enabling angiography, inversion recovery whole heart, and late gadolinium enhancement imaging in a single study.

BACKGROUND: The use of gadolinium contrast agents in cardiovascular magnetic resonance is well-established and serves to improve both vascular imaging as well as enable late gadolinium enhancement (LGE) imaging for tissue characterization. Currently, gadofosveset trisodium, an intravascular contrast agent, combined with a three-dimensional inversion recovery balanced steady state free precession (3D IR bSSFP) sequence, is commonly used in pediatric cardiac imaging and yields excellent vascular imaging, but cannot be used for late gadolinium enhancement. Gadofosveset use remains limited in clinical practice, and manufacture was recently halted, thus an alternative is needed to allow 3D IR bSSFP and LGE in the same study. METHODS: Here we propose a protocol to give a bolus of 0.1 mL/kg = 0.1 mmol/kg gadobutrol (GADAVIST/GADOVIST) for time-resolved magnetic resonance angiography (MRA). Subsequently, 0.1 mmol/kg is diluted up to 5 or 7.5 mL with saline and then loaded into intravenous tubing connected to the patient. A 0.5 mL short bolus is infused, then a slow infusion is given at 0.02 or 0.03 mL/s. Image navigated (iNAV) 3D IR bSSFP imaging is initiated 45-60 s after the initiation of the infusion, with a total image acquisition time of ~5 min. If necessary, LGE imaging using phase sensitive inversion recovery reconstruction (PSIR) is performed at 10 min after the infusion is initiated. RESULTS: We have successfully performed the above protocol with good image quality on 10 patients with both time-resolved MRA and 3D IR bSSFP iNAV imaging. Our initial attempts to use pencil beam respiratory navigation failed due to signal labeling in the liver by the navigator. We have also performed 2D PSIR LGE successfully, with both LGE positive and LGE negative results. CONCLUSION: A bolus of gadobutrol, followed later by a slow infusion, allows time-resolved MRA, 3D IR bSSFP using the iNAV navigation technique, and LGE imaging, all in a single study with a single contrast agent.

Coronary artery size and origin imaging in children: a comparative study of MRI and trans-thoracic echocardiography.

BACKGROUND: The purpose of this study was to see how coronary magnetic resonance angiography (CMRA) compared to echocardiography for the detection of coronary artery origins and to compare CMRA measurements for coronary dimensions in children with published echocardiographic reference values. METHODS: Enrolled patients underwent dual cardiac phase CMRA and echocardiography under the same anesthetic. Echocardiographic measurements of the right coronary artery (RCA), left anterior descending (LAD) and left main (LM) were made. CMRA dimensions were assessed manually at the same points as the echocardiographic measurements. The number of proximal LAD branches imaged was also recorded in order to give an estimate of distal coronary tree visualization. RESULTS: Fifty patients (24 boys, mean age 4.0 years (range 18 days to 18 years)) underwent dual-phase CMRA. Coronary origins were identified in 47/50 cases for CMRA (remaining 3 were infants aged 3, 9 and 11 months). In comparison, origins were identified in 41/50 cases for echo (remaining were all older children). CMRA performed better than echocardiography in terms of distal visualization of the coronary tree (median 1 LAD branch vs. median 0; p = 0.001). Bland-Altman plots show poor agreement between echocardiography and CMRA for coronary measurements. CMRA measurements did vary according to cardiac phase (systolic mean 1.90, s.d. 0.05 mm vs. diastolic mean 1.84, s.d. 0.05 mm; p = 0.002). CONCLUSIONS: Dual-phase CMRA has an excellent (94 %) success rate for the detection of coronary origins in children. Newborn infants remain challenging and echocardiography remains the accepted imaging modality for this age group. Echocardiographic reference ranges are not applicable to CMRA measurements as agreement was poor between modalities. Future coronary reference values, using any imaging modality, should quote the phase in which it was measured.

Towards highly accelerated Cartesian time-resolved 3D flow cardiovascular magnetic resonance in the clinical setting.

BACKGROUND: The clinical applicability of time-resolved 3D flow cardiovascular magnetic resonance (CMR) remains compromised by the long scan times associated with phase-contrast imaging. The present work demonstrates the applicability of 8-fold acceleration of Cartesian time-resolved 3D flow CMR in 10 volunteers and in 9 patients with different congenital heart diseases (CHD). It is demonstrated that accelerated 3D flow CMR data acquisition and image reconstruction using k-t PCA (principal component analysis) can be implemented into clinical workflow and results are sufficiently accurate relative to conventional 2D flow CMR to permit for comprehensive flow quantification in CHD patients. METHODS: The fidelity of k-t PCA was first investigated on retrospectively undersampled data for different acceleration factors and compared to k-t SENSE and fully sampled reference data. Subsequently, k-t PCA with 8-fold nominal undersampling was applied on 10 healthy volunteers and 9 CHD patients on a clinical 1.5 T MR scanner. Quantitative flow validation was performed in vessels of interest on the 3D flow datasets and compared to 2D through-plane flow acquisitions. Particle trace analysis was used to qualitatively visualise flow patterns in patients. RESULTS: Accelerated time-resolved 3D flow data were successfully acquired in all subjects with 8-fold nominal scan acceleration. Nominal scan times excluding navigator efficiency were on the order of 6 min and 7 min in patients and volunteers. Mean differences in stroke volume in selected vessels of interest were 2.5 ± 8.4 ml and 1.63 ± 4.8 ml in volunteers and patients, respectively. Qualitative flow pattern analysis in the time-resolved 3D dataset revealed valuable insights into hemodynamics including circular and helical patterns as well as flow distributions and origin in the Fontan circulation. CONCLUSION: Highly accelerated time-resolved 3D flow using k-t PCA is readily applicable in clinical routine protocols of CHD patients. Nominal scan times of 6 min are well tolerated and allow for quantitative and qualitative flow assessment in all great vessels.

Higher dose dobutamine stress MR imaging in repaired Tetralogy of Fallot: observer variance of volumetric assessment compared with normal volunteers.

PURPOSE: To investigate changes in image quality and observer variance between rest and higher-dose dobutamine stress MR imaging (DS-MR) in tetralogy of Fallot (TOF) patients and in a group of normal healthy volunteers using both axial and short axis orientation for cardiac volumetric assessment. MATERIALS AND METHODS: Eighteen adult patients (age 34 ± 13) with TOF and severe pulmonary regurgitation and 10 healthy volunteers underwent ventricular MR volumetry at baseline and during dobutamine infusion of 10 µg/kg/min and 20 µg/kg/min. Inter-observer and intra-observer agreement was calculated by coefficient of variance (COV). RESULTS: Inter-observer comparison showed good agreement for left ventricle (LV) and right ventricle (RV) end-diastolic volumes at rest and both stress levels in TOF patients (axial geometry) and in normal volunteers (short axis). During dobutamine stress, the COV in TOF patients increased for LV end-systolic volume (LV-ESV) with each level, suggesting less agreement between observers. In contrast, RV-ESV was much more comparable with a COV < 10 at each condition. All volumetric measurements in normal volunteers showed good inter-observer agreement. Excellent intra-observer agreement could be seen for all volumetric parameters with COV levels below 7. CONCLUSION: Volumetric assessment during DS-MR shows excellent inter-observer agreement, except for LV-ESV in the TOF patients at higher doses of dobutamine. The axial geometry appears to be reproducible for assessment of RV parameters, and could be considered superior to short axis imaging in patients with repaired TOF.

Guidelines and protocols for cardiovascular magnetic resonance in children and adults with congenital heart disease: SCMR expert consensus group on congenital heart disease.

Cardiovascular magnetic resonance (CMR) has taken on an increasingly important role in the diagnostic evaluation and pre-procedural planning for patients with congenital heart disease. This article provides guidelines for the performance of CMR in children and adults with congenital heart disease. The first portion addresses preparation for the examination and safety issues, the second describes the primary techniques used in an examination, and the third provides disease-specific protocols. Variations in practice are highlighted and expert consensus recommendations are provided. Indications and appropriate use criteria for CMR examination are not specifically addressed.

Three-dimensional dual-phase whole-heart MR imaging: clinical implications for congenital heart disease.

PURPOSE: To identify which rest phase (systolic or diastolic) is optimum for assessing or measuring cardiac structures in the setting of three-dimensional (3D) whole-heart imaging in congenital heart disease (CHD). MATERIALS AND METHODS: The study was approved by the institutional review board; informed consent was obtained. Fifty children (26 male and 24 female patients) underwent 3D dual-phase whole-heart imaging. Cardiac structures were analyzed for contrast-to-noise ratio (CNR) and image quality. Cross-sectional measurements were taken of the aortic arch, right ventricular (RV) outflow tract (RVOT) and pulmonary arteries. Normally distributed variables were compared by using paired t tests, and categorical data were compared by using Wilcoxon signed-rank test. RESULTS: Mean CNR and image quality were significantly (all P < .05) greater in systole for the right atrium (CNR, 8.9 vs 7.5; image quality, 438 vs 91), left atrium (CNR, 8.0 vs 5.3; image quality, 1006 vs 29), RV (CNR, 10.6 vs 8.2; image quality, 131 vs 23), LV (CNR, 9.4 vs 7.7; image quality, 125 vs 28), and pulmonary veins (CNR, 6.2 vs 4.9; image quality, 914 vs 32). Conversely, diastolic CNR was significantly higher in the aorta (9.2 vs 8.2; P = .013) and diastolic image quality was higher for the left pulmonary artery (238 vs 62; P = .007), right pulmonary artery (219 vs 35; P < .001), and for imaging of an area after an arterial stenosis (164 vs 7; P < .001). All aortic arch and RVOT cross-sectional measurements were significantly (P < .05) greater in systole (narrowest point of arch, 70 vs 53 mm(2); descending aorta, 71 vs 58 mm(2); transverse arch, 293 vs 275 mm(2); valvar RVOT, 291 vs 268 mm(2); supravalvar RVOT, 337 vs 280 mm(2); prebifurcation RVOT, 329 vs 259 mm(2)). CONCLUSION: Certain structures in CHD are better imaged in systole and others in diastole, and therefore, the dual-phase approach allows a higher overall success rate. This approach also allows depiction of diameter changes between systole and diastole and is therefore preferable to standard single-phase sequences for the planning of interventional procedures.

Cross-sectional and in-plane coronary vessel wall imaging using a local inversion prepulse and spiral read-out: a comparison between 1.5 and 3 Tesla.

PURPOSE: To compare cross-sectional and in-plane coronary vessel wall imaging using a spiral readout at 1.5 and 3 Tesla (T). MATERIALS AND METHODS: Free-breathing coronary vessel wall imaging using a local inversion technique and spiral readout was implemented. Images were acquired in ten healthy adult subjects on a 3T clinical scanner using a 32-element cardiac coil and repeated on a 1.5T clinical scanner using a 5-element coil. RESULTS: Cross-sectional and in-plane spiral vessel wall imaging was performed at both 1.5 and 3T. In cross-sectional images, artifact scores were superior at 1.5T (P < 0.05) but no significant difference was found in image quality scores compared with 3T. Image quality (P < 0.01) and artifact scores (P < 0.01) were found to be superior for in-plane images at 1.5T. Vessel wall sharpness in the in-plane orientation was also found to be higher at 1.5T (P < 0.03). CONCLUSION: Although excellent in-plane coronary vessel wall images can be acquired at 3T, the overall robustness may be affected by off-resonance blurring due to increased B0 inhomogeneity compared with 1.5T.

Single breath-hold assessment of cardiac function using an accelerated 3D single breath-hold acquisition technique--comparison of an intravascular and extravascular contrast agent.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is the current gold standard for the assessment of left ventricular (LV) function. Repeated breath-holds are needed for standard multi-slice 2D cine steady-state free precession sequences (M2D-SSFP). Accelerated single breath-hold techniques suffer from low contrast between blood pool and myocardium. In this study an intravascular contrast agent was prospectively compared to an extravascular contrast agent for the assessment of LV function using a single-breath-hold 3D-whole-heart cine SSFP sequence (3D-SSFP). METHODS: LV function was assessed in fourteen patients on a 1.5 T MR-scanner (Philips Healthcare) using 32-channel coil technology. Patients were investigated twice using a 3D-SSFP sequence (acquisition time 18-25 s) after Gadopentetate dimeglumine (GdD, day 1) and Gadofosveset trisodium (GdT, day 2) administration. Image acquisition was accelerated using sensitivity encoding in both phase encoding directions (4xSENSE). CNR and BMC were both measured between blood and myocardium. The CNR incorporated noise measurements, while the BMC represented the coeffiancy between the signal from blood and myocardium [1]. Contrast to noise ratio (CNR), blood to myocardium contrast (BMC), image quality, LV functional parameters and intra-/interobserver variability were compared. A M2D-SSFP sequence was used as a reference standard on both days. RESULTS: All 3D-SSFP sequences were successfully acquired within one breath-hold after GdD and GdT administration. CNR and BMC were significantly (p < 0.05) higher using GdT compared to GdD, resulting in an improved endocardial definition. Using 3D-SSFP with GdT, Bland-Altman plots showed a smaller bias (95% confidence interval LVEF: 9.0 vs. 23.7) and regression analysis showed a stronger correlation to the reference standard (R2 = 0.92 vs. R2 = 0.71), compared to 3D-SSFP with GdD. CONCLUSIONS: A single-breath-hold 3D-whole-heart cine SSFP sequence in combination with 32-channel technology and an intravascular contrast agent allows for the accurate and fast assessment of LV function.

Cyanosis in a 9-month-old child after repair of total anomalous pulmonary venous return.

A 9-month-old girl presented with cyanosis after correction of total anomalous pulmonary venous return (TAPVR) to the coronary sinus in the neonatal period. During corrective surgery, the right superior vena cava (RSVC) was damaged and re-anastomosed to the right atrium. Echocardiography showed increased flow velocity in the pulmonary venous confluence. Therefore, pulmonary venous obstruction was suspected. However, subsequent cardiac MRI revealed a stenosed RSVC as well as a dilated left superior vena cava (LSVC) draining from the left innominate vein into the pulmonary venous confluence. The re-recruited LSVC drained deoxygenated blood into the systemic circulation, causing cyanosis. After uncomplicated placement of a stent in the narrowed RSVC and occlusion of the LSVC, transcutaneous saturations normalised immediately.

Velocity encoded mitral valve inflow cine: A novel and more reproducible method to determine cardiac rest periods during coronary magnetic resonance angiography.

A high temporal resolution, 4-chamber (4CH) cine is the standard method for determining cardiac rest periods during whole heart coronary magnetic resonance angiography (CMRA). We evaluated the image quality and reproducibility between the 4CH cine method and a novel approach using a velocity encoded mitral valve inflow cine (MVI). The goal of this study was to compare the quality of CMRAs utilizing MVI versus 4CH methods. Sharpness and vessel length for the LCA and RCA using each method were determined using Soap Bubble and two blinded observers independently assessed coronary image quality. Offline analysis on a separate, retrospective cohort (n = 25) was used to compare MVI and 4CH reproducibility. In the prospectively evaluated cohort there was no difference in overall vessel sharpness (4CH vs MVI mean ± SD) (31.0 ± 5.5% vs 30.5 ± 5.7%, p = .63), LCA vessel sharpness (30.0 ± 5.4% vs 31.1 ± 8.2%, p = .44), LCA length (4.7 ± 1.4 cm vs 4.6 ± 1.6 cm, p = .66), RCA vessel sharpness (32.1 ± 6.9% vs 31.1 ± 7.7%, p = .55), RCA length (5.51 ± 2.6 cm vs 5.95 ± 2.4 cm, p = .38), or image quality rating (2.66 vs 2.62, p = .80) between methods. In the retrospective cohort, the MVI method had 5.4% lower inter-observer variability (95% CI 3.7,7.2%, p < .0001) and 3.9% lower intra-observer variability (95% CI 2.4,5.4%, p < .0001) than the 4CH method. MVI is a technically feasible and more reproducible method to determine cardiac rest periods compared to 4CH while preserving vessel sharpness, vessel length & image quality.

Detection of coronary artery anomalies in infants and young children with congenital heart disease by using MR imaging.

PURPOSE: To evaluate the feasibility and accuracy of magnetic resonance (MR) coronary angiography for the detection of coronary artery anomalies in infants and children by using surgical findings as a reference. MATERIALS AND METHODS: The data analysis was approved by the institutional review board. One hundred children with congenital heart disease underwent MR coronary angiography while under general anesthesia (mean age ± standard deviation, 3.9 years ± 3; age range, 0.2-11 years). A navigator-gated, T2-prepared, three-dimensional steady-state free precession whole-heart protocol (isotropic voxel size, 1.0-1.3 mm(3); mean imaging time, 4.6 minutes ± 1.2; mean navigator efficiency, 70%; 3-mm gating window) was used after injection of gadopentetate dimeglumine. The cardiac rest period (end systole or middiastole) and acquisition window were prospectively assessed for each patient. Coronary artery image quality (score of 0 [nondiagnostic] to 4 [excellent]), vessel sharpness, and coronary artery anomalies were assessed by two observers. Surgery was performed in 58 patients, and those findings were used to define accuracy. Variables were assessed between age groups by using either analysis of variance or Kruskal-Wallis tests. RESULTS: Diagnostic image quality (score, ≥1 for all coronary artery segments) was obtained in 46 of the 58 patients (79%) who underwent surgery. The origin and course of the coronary artery anatomy depicted with MR imaging was confirmed at surgery in all 46 patients-including the four (9%) with substantial coronary artery anomalies. Diagnostic-quality images were obtained in 84 of the 100 patients. The rate of success improved significantly when patients were older than 4 months (88% for patients >4 months vs 17% for patients ≤4 months, P < .001). CONCLUSION: Improved whole-heart MR coronary angiography enables accurate detection of abnormal origin and course of the coronary artery system even in very young patients with congenital heart disease.

Congenital heart disease: cardiovascular MR imaging by using an intravascular blood pool contrast agent.

PURPOSE: To compare the image quality and diagnostic performance of a contrast agent-specific inversion-recovery (IR) steady-state free precession (SSFP) magnetic resonance (MR) imaging sequence performed by using an intravascular contrast agent (gadofosveset trisodium) with those of a commonly used T2-prepared SSFP sequence performed by using an extravascular (gadopentetate dimeglumine) and an intravascular (gadofosveset trisodium) contrast agent in patients with congenital heart disease (CHD). MATERIALS AND METHODS: The local ethics committee and the United Kingdom Medicines and Healthcare products Regulatory Agency approved this study. Patient informed consent was obtained. Twenty-three patients with CHD were examined by using a 1.5-T MR imaging unit and a 32-channel coil. Gadopentetate dimeglumine and gadofosveset trisodium were used in the same patient on consecutive days. Vessel wall sharpness, contrast-to-noise ratios (CNRs), image quality, and diagnostic performance achieved by using the IR SSFP sequence with gadofosveset trisodium were compared with those achieved by using the T2-prepared SSFP sequence with gadopentetate dimeglumine and gadofosveset trisodium and with those achieved at respective contrast material-enhanced MR angiographic examinations. The Wilcoxon rank sum test was used to compare categoric variables; t tests were used to compare continuous variables. RESULTS: Use of the IR SSFP sequence with gadofosveset trisodium significantly improved vessel wall sharpness, CNRs, and image quality (P < .05 for all) for all investigated intra- and extracardiac structures compared with the T2-prepared SSFP sequence with gadopentetate dimeglumine and gadofosveset trisodium and the respective contrast-enhanced MR angiographic examinations. With use of the IR SSFP sequence with gadofosveset trisodium, new, unsuspected diseases (five [22%] of 23) were diagnosed, while other diseases could be excluded (15 [65%] of 23). Information available from echocardiography (n = 23), conventional angiography (n = 4), and/or surgery (n = 1) confirmed all diagnoses. CONCLUSION: IR SSFP with gadofosveset trisodium improved image quality and diagnostic performance, allowing a more accurate and complete assessment of cardiovascular anatomy in patients with CHD compared with T2-prepared SSFP with gadopentetate dimeglumine and gadofosveset trisodium and respective contrast-enhanced MR angiographic examinations.

Congenital heart disease in children: coronary MR angiography during systole and diastole with dual cardiac phase whole-heart imaging.

PURPOSE: To assess the optimal timing for coronary magnetic resonance (MR) angiography in children with congenital heart disease by using dual cardiac phase whole-heart MR imaging. MATERIALS AND METHODS: The local institutional review board approved this study, and informed consent was obtained from parents or guardians. Thirty children (13 girls; overall mean age, 5.01 years) were examined with a 1.5-T MR system. A free-breathing three-dimensional steady-state free precession dual cardiac phase sequence was used to obtain MR angiographic data during end-systolic and middiastolic rest periods. Vessel length, diameter, and sharpness, as well as image quality of the coronary artery segments, were analyzed and compared by using Bland-Altman plots, linear regression analysis, the t test, and Wilcoxon signed rank tests. RESULTS: Optimal coronary artery imaging timing was patient dependent and different for each coronary artery segment (36 segments favored end systole, 28 favored middiastole). In 15 patients (50%), different segments favored different cardiac phases within the same patient. Image quality and vessel sharpness degraded with higher heart rates, with a similar correlation for end systole (right coronary artery [RCA], 0.39; left main [LM] coronary artery, 0.46; left anterior descending [LAD] artery, 0.51; and left circumflex [LCX] artery, 0.50) and middiastole (RCA, 0.34; LM, 0.45; LAD, 0.48; and LCx, 0.55). Mean image quality difference or mean vessel sharpness difference showed no indication to prefer a specific cardiac phase. CONCLUSION: The optimal cardiac rest period for coronary MR angiography in children with congenital heart disease is specific for each coronary artery segment. Dual cardiac phase whole-heart coronary MR angiography enables optimal coronary artery visualization by retrospectively choosing the optimal imaging rest period.