Steady-state Free Precession Cine Research Articles

Evaluation of Myocardial Strain in Patients With Amyloidosis Using Cardiac Magnetic Resonance Feature Tracking

PurposeTo study the use of cardiac magnetic resonance (CMR) feature tracking technique in evaluation of myocardial amyloidosis. Materials and MethodsCMR scans of 28 patients with biopsy proven myocardial amyloidosis and 35 controls were reviewed. Conventional short axis, vertical long axis, and 4-chamber cine steady-state free precession images from CMR scans were used to generate radial, circumferential, and longitudinal myocardial strain maps using feature tracking software. Global and regional peak radial, circumferential, and longitudinal strain values were computed. ResultsThere were significant decreases in radial, circumferential, and longitudinal strains in patients with myocardial amyloidosis globally and across layers (all P < 0.001). Strain was relatively preserved for the apex and most affected for the basal level. The area under the receiver operating characteristic curve for base peak radial, circumferential, and longitudinal strain 0.899, 0.884, and 0.866 and cut offs of 22.9, −13.3, and −10.9, respectively, were determined by receiver operating characteristic analysis. CMR feature tracking strain analysis of base-level strain parameters was able to differentiate patients with myocardial amyloidosis from those without myocardial amyloid with high sensitivity (82.5%) and specificity (82.9%) particularly for radial strain. The maximum sensitivity (89.3%) was achieved if any of the 3 parameters were abnormal, and the maximum specificity (88.6%) when all 3 parameters were abnormal. ConclusionMyocardial amyloidosis produces significant changes in regional and global strain parameters, and the peak radial and circumferential strain are the most affected at the basal layer.

Higher resolution cine imaging with compressed sensing for accelerated clinical left ventricular evaluation

To assess the clinical feasibility of a compressed sensing cine magnetic resonance imaging (MRI) sequence of both high temporal and spatial resolution (CS_bSSFP) in comparison to a balanced steady-state free precession cine (bSSFP) sequence for reliable quantification of left ventricular (LV) volumes and mass. Segmented MRI cine images were acquired on a 1.5T scanner in 50 patients in the LV short-axis stack orientation using a retrospectively gated conventional bSSFP sequence (generalized autocalibrating partially parallel acquisition [GRAPPA] acceleration factor 2), followed by a prospectively triggered CS_bSSFP sequence with net acceleration factor of 8. Image quality was assessed by published criteria. Comparison of sequences was made in LV volumes and mass, image quality score, quantitative regional myocardial wall motion, and imaging time using Pearson's correlation, Bland-Altman and paired 2-tailed Student's t-test. Differences (bSSFP minus CS_bSSFP, mean ± SD) and Pearson's correlations were 14.8 ± 16.3 (P = 0.31) and r = 0.98 (P < 0.0001) for end-diastolic volume (EDV), 8.4 ± 11.3 (P = 0.54) and r = 0.99 (P < 0.0001) for end-systolic volume (ESV), -0.4 ± 2.5 (P = 0.87) and r = 0.97 (P < 0.0001) for EF, and -0.9 ± 11.8 (P = 0.92) and r = 0.97 (P < 0.0001) for LV mass. Bland-Altman analyses [bias and (limits of agreement)] revealed strong agreement in LVEDV [8.7 ml, (-12.1, 29.6)], LVESV [4.3 ml, (-11.9, 20.6)], LVEF [-0.02%, (-5.37, 5.33)], and myocardial mass [-6.1 g, (-14.7, 26.9)]. Image quality was comparable with a similar mean score (P = 0.42), with a good correlation in image quality observed (r = 0.68, P < 0.0001). Quantitative regional myocardial wall motion demonstrated strong correlation between the sequences (r = 0.87, P < 0.0001). Imaging time was significantly shorter for the CS_bSSFP sequence (1.1 ± 0.5 versus 5.6 ± 1.6 min, P < 0.0001). The novel high-resolution cine CS_bSSFP accurately and reliably quantitates LV volumes and mass, shortens acquisition times, and is clinically feasible. 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;45:1693-1699.

WE-FG-206-04: Comprehensive Evaluation of Left Ventricular (LV) Filling and Ejection Using High Frame Rate Cine MR Imaging: Key Technical and Methodological Requirements

Purpose: Unlike echocardiography which can quantify both LV filling and ejection, cine steady state free precession sequence (SSFP)-despite its high intrinsic signal and contrast to noise ratio, accuracy and precision of volume measurements-, is mostly relegated to quantifying LV ejection. The steady-state requirement typically constrains SSFP sequence to a breathhold (and limited temporal resolution). We describe: (a) free breathing cine SSFP approach that meets the SS requirement allowing high frame rate acquisition, (b) two MRI indices based on time-LV volume (TV) change during filling and compare against echocardiagraphic diastolic index (E/A ratio), and (c) evaluate the effect of temporal resolution on: LV volumes; ejection and filling rates; and normalized indices of systolic and diastolic function. Methods: A stack of contiguous LV short axis slices at high temporal resolution (τ=15 ms) was acquired using an in-house respiratory-triggered (RT), SS prepared, cardiac gated, free-breathing cine SSFP sequence (TR/TE/flip: 3.2 ms/1.5 ms/55°). All 24 study subjects provided written informed consent per IRB requirements. Subjects underwent both echo and MRI in one imaging session. From the expert-drawn contours, TV curve, and its derivative (dV/dt) were generated and these curves were downsampled to rates at 2τ,3τ,and 4τ. From TV and dV/dt curves during the early filling period (EFP) and late filling periods (LFP), volume based (VEFP/VLFP) and rate based (REFP/RLFP) diastolic indices were respectively defined, and calculated for each temporal resolution. Results: VEFP/VLFP and REFP/RLFP correlated well with E/Aecho. As temporal resolution declined from τ to 3τ, absolute percentage errors were: LV chamber volumes 20%.. Conclusion: By incorporating SS prep, RT can be used to obtain high frame rate cine SSFP sequence that can evaluate both LV systolic and diastolic function. Temporal resolution of cine SSFP is a key determinant of error in rate based diastolic indices. Research was partly supported by funding from Philips Healthcare.

003 Detecting hypertensive heart disease: The additive value of cardiovascular magnetic resonance imaging

Introduction International hypertension guidelines advise screening for hypertensive heart disease (HHD) to aid risk stratification. Cardiac magnetic resonance (CMR) is the current non-invasive gold-standard for assessing ventricular structure/function. We aimed to determine the additive value of CMR in hypertensives over echocardiography. Methods 85 subjects (60% men, office systolic BP: 165 ± 28mmHg, office diastolic BP: 94 ± 14mmHg) from our tertiary hypertension clinic with preceding echo underwent 1.5T CMR. Left ventricular mass and volumes were estimated from short-axis steady-state free precession cines. LVH was defined on the basis of echo and CMR normal reference ranges. The presence and pattern of myocardial late gadolinium enhancement (LGE) was documented. Results Overall, there was no difference in prevalence of LVH by echo compared to CMR (68% vs 66%, P = 0.746). However, there was a discrepancy between echo and CMR in 28%. Relative to CMR gold-standard, echo over-diagnosed LVH in 15% and missed LVH in 13%. The diagnostic performance of echo at detecting LVH was as follows: specificity 55%, sensitivity 80%, positive predictive value 78%, negative predictive value 59% and overall accuracy 72%. Ischaemic LGE was present in 7% of subjects and non-ischaemic LGE was present in 9%. Conclusion Echocardiography over-diagnosed and under-diagnosed LVH in an important minority of patients. LGE tissue characterisation is unique to CMR and identified ischaemic and non-ischaemic myocardial fibrosis is an important minority of hypertensives. Our findings support an extended role of CMR in hypertension where documenting in the presence/absence of HHD may have clinical management implications.

21 Feature tracking cardiac magnetic resonance to assess LV mechanics in different cardiac overload caused by aortic valve disease

Background In aortic valve disease, left ventricular (LV) dimensions and ejection fraction are important parameters for decision making. However, the effects of pressure overload caused by aortic stenosis or/and volume overload, due to aortic regurgitation, lead to different LV remodelling, concentric and eccentric hypertrophy, respectively, which may differently alter LV mechanics. We aimed to characterise LV mechanics, in terms of longitudinal strain/deformation using feature tracking cardiac magnetic resonance (FT-CMR) in patients with various degree of aortic stenosis and aortic regurgitation and preserved LV ejection fraction (LVEF). Methods Seventy-one patients (14 with normal valve function, 29 with aortic stenosis and 28 with aortic regurgitation), mean age 45 ± 19 years, 70% men, who underwent clinically indicated CMR and showed preserved LVEF (>50%) were included. LV volumes, LVEF and mass were measured on steady-state free precession (SSFP) cine images. FT-CMR analysis was performed offline using tissue-tracking software (CVI42, Circle Cardiovascular Imaging Inc.) to estimate LV global longitudinal strain (GLS) from two long-axis SSFP cine images (Figure 1). To correct for the LV remodelling process, LV GLS was corrected for LV end-diastolic volume. Results There were significant differences in LV volumes, mass and ejection fraction across the 3 groups of patients (Table 1): patients with aortic regurgitation showed significantly larger LV volumes, and lower LVEF compared to patients with normal aortic valve function and patients with aortic stenosis. There were no differences in LV GLS across the groups. However, after correcting for LV end-diastolic volume, patients with aortic regurgitation showed more impaired LV GLS as compared to the other groups. Conclusions LV mechanics significantly differ across normal functioning and different type of aortic valve dysfunction (stenosis and regurgitation), with aortic regurgitation showing the most impaired LV GLS corrected for LV end-diastolic volume, despite preserved LVEF.

22 Intra-ventricular myocardial deformation strain analysis in healthy volunteers: regional variation and implications for regional myocardial disease processes

Ejection fraction (EF) is a traditional marker of systolic function. However, it may not detect early, subtle cardiac disease with regional predilection. The aim of this study was to define regional intra-ventricular variation in myocardial strain in a cohort of healthy volunteers using Tissue-tracking cardiac magnetic resonance (CMR). Methods Healthy volunteers were recruited (n = 94, age range 20–79 years, 54% male). CMR at 1.5T was performed. Tissue-tracking software (CVI42, Circle Cardiovascular Imaging Inc.) estimated myocardial strain from the long-axis and the short-axis steady-state free precession (SSFP) cine images (Figure 1). The entire cohort was analysed by two independent readers. Inter-observer variability was also assessed. Myocardial segments were defined in accordance to the American Heart Association 16-segment model. Regional variations in circumferential and radial strain between basal, mid-cavity and apical segments as well as between left ventricle walls were assessed. Statistical analysis was performed using paired t test (p Results Inter-observer reproducibility analyses were excellent for mid-cavity and apical radial and circumferential strain values. On the other hand, reproducibility was not as good for basal segments for both deformation directions. Regional variations in strain (Table 1) revealed a statistically significant increase in deformation of the apical segments compared to the basal and mid-cavity ones for both radial and circumferential strain. Analysis of the different LV walls deformations indicated lowest values in the septum in all subjects, as well as across all age and gender subgroups. Conclusion This is the first study to demonstrate that there is a positive gradient toward the apex in both circumferential and radial strain using CMR-derived myocardial strain analysis. Furthermore, we also showed that the interventricular septum is the segment with lowest deformation values. These findings are important, as a comprehensive understanding of normal intra-ventricular regional variation is needed before this new tool can be implemented in routine clinical practice.

MR feature tracking in patients with MRI-conditional pacing systems: The impact of pacing.

To develop feature tracking (FT) software to perform strain analysis on conventional (nontagged) cardiac magnetic resonance imaging (MRI) function images. With the advent of MRI-conditional pacemaker systems, effects of cardiac pacing on myocardial strain can be studied using MR. In this study the impact of pacing on left ventricular (LV) strain was investigated using MR-FT in patients with an MRI-conditional cardiac implantable electronic device (CIED). FT was performed on 32 1.5T MR studies (16 patients with an MRI-conditional CIED and 16 control patients with normal scans). Short- and long-axis steady state free precession (SSFP) cines were used for the FT analysis. Strain was assessed using CVI(42) software (Circle Cardiovascular Imaging, Alberta, Canada). In addition, the intra- and interobserver variability was determined using the intraclass correlation coefficient. Of the 16 patients with an MRI-conditional CIED, five patients were paced during the MRI exam. Despite the occasional presence of susceptibility artifacts induced by the CIED, radial, circumferential, and longitudinal strain parameters could be derived for all patients. Peak radial strain and peak circumferential strain were reduced during pacing when compared to the control group; for radial strain: 20.1 ± 4.7% vs. 33.1 ± 6.9%, P < 0.001, and for circumferential strain -7.5 ± 3.5% vs. -14.9 ± 3.2%, P < 0.05. Peak strain parameters were reproducible on an intra- and interobserver level. MR-FT is feasible in patients with an MRI-conditional CIED and can be used to quantify regional wall motion. J. MAGN. RESON. IMAGING 2016;44:964-971.

P22 Early experience of multi-sequence fetal cardiac magnetic resonance imaging within a clinical fetal cardiology service

Background Fetal cardiac MRI offers the potential for a safe, radiation-free adjunct to echocardiography. In practice, its use has been limited by the technical challenges imposed by the small size of the fetal heart, the lack of external gating, and gross fetal and maternal movements. We present our initial experience of 20 fetal cases assessed by MRI, referred after routine fetal cardiology assessment to resolve specific points of diagnostic uncertainty. Methods Referrals were based on the judgements of the attending fetal cardiologists between June 2014 and May 2015. Following a three-plane localiser, gross fetal movement was assessed with a balanced steady-state free precession (bSSFP) cine. Half-Fourier single-shot turbo spin echo (HASTE) and bSSFP gradient echo sequences were used for diagnostic imaging. The MRI diagnosis was subsequently compared with postnatal findings. Results 20 fetal cardiac MRI scans were performed over the referral period, at an average gestational age of 32 +4 weeks, (range 26 +4 –38 +1 weeks). 3 scans were abandoned due to excessive fetal movement or inadequate visualisation. The most frequent referral indications were suspected coarctation of the aorta/abnormal arch anatomy (n = 9), cardiac masses or diverticulums (n = 5), and assessment of pulmonary vasculature (n = 4). HASTE sequences produced T2-weighted “black-blood” images, useful for assessing extracardiac vasculature (figure 1). Balanced SSFP sequences showed good contrast between the blood pool and surrounding tissue and were useful for intracardiac structures; however these were more susceptible to motion artefacts. Real-time SSFP sequences allowed for dynamic assessment of moving structures (e.g. masses/diverticulums-figure 2). Using a combination of sequences we were able to accurately characterise rhabdomyomas in 3 patients. In total, of the 17 scans with useful data, MRI was diagnostic in 15. Neonatal coarctation was incorrectly predicted in one case, and no postnatal data was available in another due to fetal demise. Conclusions Certain fetal cardiovascular abnormalities may be difficult to diagnose with ultrasound alone, reflected in the referral pattern we observed for MRI. Our preliminary experience suggests that MRI can provide safe and useful complimentary imaging in this cohort within a tertiary fetal cardiac unit. As technical challenges continue to be addressed, prenatal MRI may develop a more prominent role in routine fetal cardiovascular assessment.

Comparison of two single-breath-held 3-D acquisitions with multi-breath-held 2-D cine steady-state free precession MRI acquisition in children with single ventricles.

Breath-held two-dimensional balanced steady--state free precession cine acquisition (2-D breath-held SSFP), accelerated with parallel imaging, is the method of choice for evaluating ventricular function due to its superior blood-to-myocardial contrast, edge definition and high intrinsic signal-to-noise ratio throughout the cardiac cycle. The purpose of this study is to qualitatively and quantitatively compare the two different single-breath-hold 3-D cine SSFP acquisitions using 1) multidirectional sensitivity encoding (SENSE) acceleration factors (3-D multiple SENSE SSFP), and 2) k-t broad-use linear acceleration speed-up technique (3-D k-t SSFP) with the conventional 2-D breath-held SSFP in non-sedated asymptomatic volunteers and children with single ventricle congenital heart disease. Our prospective study was performed on 30 non-sedated subjects (9 healthy volunteers and 21 functional single ventricle patients), ages 12.5 +/- 2.8years. Two-dimensional breath-held SSFP with SENSE acceleration factor of 2, eight-fold accelerated 3-D k-t SSFP, and 3-D multiple SENSE SSFP with total parallel imaging factor of 4 were performed to evaluate ventricular volumes and mass in the short-axis orientation. Image quality scores (blood myocardial contrast, edge definition and interslice alignment) and volumetric analysis (end systolic volume, end diastolic volume and ejection fraction) were performed on the data sets by experienced users. Paired t-test was performed to compare each of the 3-D k-t SSFP and 3-D multiple SENSE SSFP clinical scores against 2-D breath-held SSFP. Bland-Altman analysis was performed on left ventricle (LV) and single ventricle volumetry. Interobserver and intraobserver variability in volumetric measurements were determined using intraclass coefficients. The clinical scores were highest for the 2-D breath-held SSFP images. Between the two 3-D sequences, 3-D multiple SENSE SSFP performed better than 3-D k-t SSFP. Bland-Altman analysis for volumes indicated that variability was more between 3-D k-t SSFP and 2-D breath-held SSFP acquisitions than between 3-D multiple SENSE SSFP and 2-D breath-held SSFP acquisitions. In the non-sedated population, interslice alignment scores were better for 3-D k-t SSFP and 3-D multiple SENSE SSFP than 2-D breath-held SSFP. The blood-myocardial contrast and edge definition scores were better for 2-D breath-held SSFP than 3-D k-t SSFP and 3-D multiple SENSE SSFP. Scan duration was shorter for 3-D acquisition sequences compared to the 2-D breath-held stack. Three-dimensional k-t SSFP and 3-D multiple SENSE for ventricular volumetry release the constraints of multiple breath-holds in children and overcome problems related to interslice misalignment caused by inconsistent amplitude of breathing. Three-dimensional multiple SENSE SSFP performed better in our pediatric population than 3-D k-t SSFP. However, these 3-D sequences produce lower-quality diagnostic images than the gold standard 2-D breath-held SSFP sequence.

Right ventricular function and adaption after hemi-Fontan completion in children with hypoplastic left heart syndrome

Background The systemic right ventricle (RV) in patients with hypoplastic left heart syndrome (HLHS) is prone to failure. The complex geometry and contraction pattern of the systemic RV makes identification of patients at risk for failure challenging, especially in the light of radical changes in loading conditions during staged palliation. MRI allows for accurate quantification of cardiac volumes and provides assessment of the whole heart without restrictions in imaging planes. Recent advances in cardiac MRI analysis software allows for quantification of regional deformation from conventional balanced steady state free precession cine images. We sought to investigate changes in ventricular function before and after the hemi-Fontan (HF).

The association of left atrial volume with age, ethnicity and cardiovascular risk factors in men and women: the Multi-Ethnic Study of Atherosclerosis (MESA)

Methods LA volume indexed to body surface area (LAVi) was measured by CMR using steady-state free precession cine long and short axis images in 2576 participants of the MultiEthnic Study of Atherosclerosis (68.7 years, 53.0% women). We used gender stratified regression models to evaluate the association of LAVi as the dependent variable with demographic and cardiovascular risk factors, left ventricular (LV) parameters and diagnosis of coronary heart disease as independent variables. LAVi between ethnicities were compared using analysis of variance (ANOVA) with Tukey’s post-hoc analysis. To determine normal LA dimensions we also selected a group of participants with normal body mass index (≥18.5 and < 25 kg/m), without hypertension, diabetes, coronary heart disease, congestive heart failure, LV systolic dysfunction (defined as ejection fraction less than 50%), LV hypertrophy or atrial fibrillation (n = 285, 65.6 years, 61.8% women). Results The unadjusted mean LA volume index in the whole cohort was 36.5 ± 11.4 ml/m and was 9% smaller in men (35.9 ± 11.1 vs. 37.0 ± 11.6 ml/m, p < 0.05). LAVi was greater with age in men (b = 0.2 ml/m/yr, p < 0.0001) and women (b = 0.3 ml/m/yr, p < 0.0001). Both Chinese American men and women had significantly (p < 0.05) smaller LAVi compared to other ethnicities (Figure 2). History of coronary disease was associated with 10% larger LAVi in women (b=3.7 ml/m, p < 0.05), but not in men (p = ns). In the normal reference cohort free of cardiovascular disease there were no differences in LAVi by gender (men 34.5 ± 9.9 ml/m, women 36.0 ± 10.2 ml/m, p = 0.30).

Comparison of heart deformation analysis and cine DENSE in volunteers and heart failure patients

Background Post-processing methods have been developed to quantify myocardial strain from steady-state free-precession (SSFP) cine images. In the left ventricle (LV), global strain measurements from SSFP in healthy volunteers and in some types of heart disease compare favorably with myocardial tagging as a reference. We compared heart deformation analysis (HDA) of SSFP images and cine Displacement Encoding with Stimulated Echoes (DENSE) for the assessment of global and segmental circumferential strain (Ecc) and derivative indices in healthy volunteers and heart failure (HF) patients with left bundle branch block (LBBB).

A comparison of real-time radial GRAPPA and standard cine imaging for the evaluation of cardiac function in children and young adults

Background Segmented balanced steady state free precession (bSSFP) cine imaging is the gold standard MRI technique for assessing ventricular systolic function. The image acquisition involves ECG gating and is ideally performed during breath-hold to reduce artifacts from myocardial and respiratory motion. Real-time radial imaging with parallel imaging technique GRAPPA reconstruction (radial GRAPPA) utilizes a radial data collection scheme in combination with a through-time k-space GRAPPA technique to achieve high acceleration rates. As it is acquired during free-breathing and is not ECG-gated, it has the potential to dramatically shorten cardiac functional imaging time. As radial GRAPPA has previously only been validated in adult patients, our purpose is to compare image quality between bSSFP and radial GRAPPA for evaluating cardiac function in children and young adults.

Characterization of left and right atrial function in healthy volunteers by cardiovascular magnetic resonance.

BackgroundLeft and right atrial function show a different pattern in advanced age in order to maintain adequate ventricular filling. It has been shown that left atrial (LA) function has a prognostic value in a number of heart conditions. Cardiovascular magnetic resonance (CMR) provides high quality images of the left and right atria using high temporal resolution steady state free precession (SSFP) cine sequences. We used SSFP cines to characterize atrial function in healthy, normotensive, volunteers.MethodsWe measured maximum, preatrial contraction and minimum left and right atrial volumes in 120 healthy subjects after careful exclusion of cardiovascular abnormality (60 men, 60 women; 20 subjects per age decile from 20 to 80 years). Data were generated from 3-dimensional modeling, including tracking of the atrioventricular ring motion and time-volume curves analysis. With those measurements, all the usual parameters for left and right atrial function were calculated.ResultsGender had significant influence on some parameters of left and right atrial conduit and booster pump function. Age significantly influenced the majority of parameters of both left and right atrial function, with typically lower reservoir and conduit functions and higher booster pump function, both in males and females belonging to older age groups. CMR normal ranges were modelled for clinical use with normalization, where appropriate, for body surface area and gender, displaying parameters with respect to age.ConclusionsCMR normal reference ranges for components of left and right atrial function are provided for males and females for a wide age range.

Two-center clinical validation of free breathing respiratory triggered retrospectively cardiac gated steady-state free precession (RT-SSFP) cine imaging in adults

Two-center clinical validation of free breathing respiratory triggered retrospectively cardiac gated steady-state free precession (RT-SSFP) cine imaging in adults

Quantitative assessment of temporal stability of the myocardial signal and relative blood to myocardial contrast in free breathing respiratory triggered retrospectively cardiac gated cine steady-state free precession (RT-SSFP) imaging

Quantitative assessment of temporal stability of the myocardial signal and relative blood to myocardial contrast in free breathing respiratory triggered retrospectively cardiac gated cine steady-state free precession (RT-SSFP) imaging

Multicenter review: role of cardiovascular magnetic resonance in diagnostic evaluation, pre-procedural planning and follow-up for patients with congenital heart disease.

The number of patients with congenital heart disease (CHD) is rapidly increasing in the adult population, mainly due to the improved long-term survival. Serial follow-up with cardiac magnetic resonance imaging (CMR) is very appealing due to its non-invasive nature. CMR exam is able to provide specific information about cardiac function, hemodynamics, anatomy and tissue characterization unlikely achievable by other diagnostic techniques. CMR in CHD plays a role both in early diagnosis and in post-operative follow-up. Black Blood T1 weighted sequences are used to acquire morphological information. Cine Steady State Free Precession sequences are mainly used to provide data about cardiac function and kinesis. Hemodynamic assessment is routinely performed using phase contrast sequences, which provide reliable information concerning vessel flow pattern, cardiac output and intracardiac shunts. Magnetic Resonance Angiography (MRA) and 3D coronary MRA of the whole thorax can provide detailed morphological information regarding great vessels and proximal coronary arteries. Presence of late gadolinium enhancement suggesting myocardial macroscopic fibrosis seems to play a prognostic and diagnostic role even in this field.

Quantification of Myocardial Extracellular Volume Fraction with Cardiac MR Imaging in Thalassemia Major.

Purpose To quantify myocardial extracellular volume (ECV) by using cardiac magnetic resonance (MR) imaging in thalassemia major and to investigate the relationship between ECV and myocardial iron overload. Materials and Methods With institutional review board approval and informed consent, 30 patients with thalassemia major (mean age ± standard deviation, 34.6 years ± 9.5) and 10 healthy control subjects (mean age, 31.5 years ± 4.4) were prospectively recruited (clinicaltrials.gov identification number NCT02090699). Nineteen patients (63.3%) had prior myocardial iron overload (defined as midseptal T2* < 20 msec on any prior cardiac MR images). Cardiac MR imaging at 1.5 T included cine steady-state free precession for ventricular function, T2* for myocardial iron quantification, and unenhanced and contrast material-enhanced T1 mapping. ECV was calculated with input of the patient's hematocrit level. Peak systolic global longitudinal strain by means of speckle tracking was assessed with same-day transthoracic echocardiography. Statistical analysis included use of the two-sample t test, Fisher exact test, and Spearman correlation. Results Unenhanced T1 values were significantly lower in patients with prior myocardial iron overload than in control subjects (850.3 ± 115.1 vs 1006.3 ± 35.4, P < .001) and correlated strongly with T2* values (r = 0.874, P < .001). Patients with prior myocardial iron overload had higher ECV than did patients without iron overload (31.3% ± 2.8 vs 28.2% ± 3.4, P = .030) and healthy control subjects (27.0% ± 3.1, P = .003). There was no difference in ECV between patients without iron overload and control subjects (P = .647). ECV correlated with lowest historical T2* (r = -0.469, P = .010) but did not correlate significantly with left ventricular ejection fraction (r = -0.216, P = .252) or global longitudinal strain (r = -0.164, P = .423). Conclusion ECV is significantly increased in thalassemia major and is associated with myocardial iron overload. These abnormalities may potentially reflect diffuse interstitial myocardial fibrosis. (©) RSNA, 2015 Online supplemental material is available for this article.

Comprehensive motion-compensated highly accelerated 4D flow MRI with ferumoxytol enhancement for pediatric congenital heart disease.

To develop and evaluate motion-compensation and compressed-sensing techniques in 4D flow MRI for anatomical assessment in a comprehensive ferumoxytol-enhanced congenital heart disease (CHD) exam. A Cartesian 4D flow sequence was developed to enable intrinsic navigation and two variable-density sampling schemes: VDPoisson and VDRad. Four compressed-sensing methods were developed: A) VDPoisson scan reconstructed using spatial wavelets; B) added temporal total variation to A; C) VDRad scan using the same reconstruction as in B; and D) added motion compensation to C. With Institutional Review Board (IRB) approval and Health Insurance Portability and Accountability Act (HIPAA) compliance, 23 consecutive patients (eight females, mean 6.3 years) referred for ferumoxytol-enhanced CHD 3T MRI were recruited. Images were acquired and reconstructed using methods A-D. Two cardiovascular radiologists independently scored the images on a 5-point scale. These readers performed a paired wall motion and functional assessment between method D and 2D balanced steady-state free precession (bSSFP) CINE for 16 cases. Method D had higher diagnostic image quality for most anatomical features (mean 3.8-4.8) compared to A (2.0-3.6), B (2.2-3.7), and C (2.9-3.9) with P < 0.05 with good interobserver agreement (κ ≥ 0.49). Method D had similar or better assessment of myocardial borders and cardiac motion compared to 2D bSSFP (P < 0.05, κ ≥ 0.77). All methods had good internal agreement in comparing aortic with pulmonic flow (BA mean < 0.02%, r > 0.85) and compared to method A (BA mean < 0.13%, r > 0.84) with P < 0.01. Flow, functional, and anatomical assessment in CHD with ferumoxytol-enhanced 4D flow is feasible and can be significantly improved using motion compensation and compressed sensing. J. Magn. Reson. Imaging 2016;43:1355-1368.

Abstract 18015: “Apical Sparing” Longitudinal Strain Pattern With Cardiac MRI Correlates With LGE Distribution in Cardiac Amyloidosis

Introduction: Regional variations in longitudinal strain (LS) have been demonstrated on echocardiography in patients with cardiac amyloidosis (CA). Hypothesis: We aimed to describe regional patterns in LS using feature-tracking software applied to cardiac MRI images (CMR) in CA, hypertrophic cardiomyopathy (HCM), and Anderson-Fabry’s disease (AFD) and to relate these patterns to late gadolinium enhancement (LGE). Methods: Patients with CA (n=51) were compared to left ventricular mass index balanced patients with HCM (n=20) and AFD (n=20). LS analysis was performed using Velocity Vector Imaging (VVI) on steady state free precession cine images (4, 3, and 2-chamber views). Values were recorded for each of 18 myocardial segments. A regional LS ratio representing “apical sparing” was calculated as the ratio of the sum of the apical segmental LS values divided by the sum of the basal and mid-segmental LS values. LGE was quantified for the basal, mid, and apical myocardial segments using a threshold of 5SD above remote myocardium. A regional LGE ratio was calculated similar to the “apical sparing” ratio. Results: The regional LS ratio was significantly higher in patients with CA (1.05±0.49) than in patients with AFD (0.79±0.24; p=0.025) and HCM (0.84±0.32; p=0.025). In patients with CA there was a regional difference in LGE burden, with lower LGE in the apex (31.9±20%) compared to the basal (52.7±22%) and mid-segments (37.9±19%). The regional LGE ratio was significantly lower in patients with CA (0.34±0.14) than in patients with AFD (0.54±0.64; p&lt;0.001) and HCM (0.73±0.41; p&lt;0.001). Conclusions: Cardiac amyloidosis is characterized by regional variations in LS from base to apex. “Apical sparing” in LS is seen with CMR images and can be an additional tool to differentiate CA from other causes of LVH. The concomitant presence of a base to apex gradient in LGE burden by CMR suggests that the regional strain gradient may be associated with burden of amyloid deposition.