Comparison of Cardiac Magnetic Resonance Imaging and Echocardiography in Assessment of Left Ventricular Hypertrophy in Fabry Disease

Background

Cardiac hypertrophy in Fabry disease can be assessed using the left ventricular mass index (LVMI) with either echocardiography (LVMI-ECHO) or magnetic resonance imaging (LVMI-CMR).

Determinants of Left Ventricular Mass and Hypertrophy in Hemodialysis Patients Assessed by Cardiac Magnetic Resonance Imaging

Background and objectives: Left ventricular hypertrophy (LVH) is an independent risk factor for premature cardiovascular death in hemodialysis (HD) patients and one of the three forms of uremic cardiomyopathy. Cardiovascular magnetic resonance (CMR) is a volume-independent technique to assess cardiac structure. We used CMR to assess the determinants of left ventricular mass (LVM) and LVH in HD patients.Design, setting, participants, & measurements: A total of 246 HD patients (63.8% male; mean age 51.5 ± 12.1 yr) underwent CMR on a postdialysis day. LVM was measured from a stack of cine loops and indexed for body surface area (LVM index [LVMI]). Demographic, past biochemical, hematologic, and dialysis data were collected by patient record review. Results up to 180 d before CMR were collected. LVH was defined as LVMI >84.1 g/m² (male) or >76.4 g/m² (female).Results: A total of 157 (63.8%) patients had LVH. LVH was more common in patients with higher predialysis systolic BP, predialysis pulse pressure, and calcium-phosphate product (Ca × PO₄). Furthermore, LVH was significantly associated with higher end-diastolic and systolic volumes and lower ejection fraction. There were positive correlations with LVMI and end-diastolic and systolic volumes. There were weak positive correlations among LVMI, mean volume of ultrafiltration, and Ca × PO₄. Using multivariate linear and logistic regression (entering one BP and cardiac variable), the independent predictors of LVMI and LVH were end-diastolic volume, predialysis systolic BP, and Ca × PO₄.Conclusions: The principal determinants of LVM and LVH in HD patients are end-diastolic LV volume, predialysis BP, and Ca × PO₄.Patients with ESRD, particularly those who require hemodialysis (HD), have an increased risk for premature cardiovascular disease (CVD) (1). Left ventricular hypertrophy (LVH) is a common feature of patients with ESRD, a component of uremic cardiomyopathy and an independent risk factor for sudden cardiac death, heart failure, and cardiac arrhythmias in the general population and HD patients (2–4).Studies that have assessed independent predictors of left ventricular mass index (LVMI; corrected for body surface area [BSA]) and LVH in patients with ESRD have used echocardiography and implicated factors such as hypertension, reduced blood vessel compliance, anemia, phosphate control, and dosage of dialysis (5–7); however, accurate echocardiographic estimation of LVMI in patients with ESRD is difficult because of large variation in intravascular (and hence intraventricular) volume during the interdialytic period and during dialysis. Geometric assumptions made during calculation of LVMI from conventional M-mode echocardiography dimensions result in greater inaccuracies as a result of geometric LV distortion in patients with LVH and ESRD.Cardiac magnetic resonance (CMR) imaging provides more detailed, volume-independent measurement of cardiac structure and has been thoroughly validated using human autopsy and animal specimens (8,9). This technique has been established as the most accurate noninvasive method of assessing ventricular dimensions in patients, including those with stage 5 chronic kidney disease (10,11). In particular, measurements obtained by echocardiography tend to overestimate LVMI, particularly at higher values, when compared with CMR (12). Furthermore, pilot studies in patients with ESRD, using CMR to identify myocardial changes of uremic cardiomyopathy, have so far shown a significant reduction in long-term survival similar to previous echocardiography findings (13 and unpublished data). Thus, the aim of this study was to assess by CMR the determinants of LVMI and LVH in a cohort of HD patients.     

Assessment of Left Ventricular Ejection Fraction Calculation on Long-axis Views From Cardiac Magnetic Resonance Imaging in Patients With Acute Myocardial Infarction

To assess left ventricular ejection fraction (LVEF) accurately, cardiac magnetic resonance (CMR) can be indicated and lays on the evaluation of multiple slices of the left ventricle in short axis (CMR_SAX). The objective of this study was to assess another method consisting of the evaluation of 2 long-axis slices (CMR_LAX) for LVEF determination in acute myocardial infarction.One hundred patients underwent CMR 2 to 4 days after acute myocardial infarction. LVEF was computed by the area-length method on horizontal and vertical CMR_LAX images. Those results were compared to reference values obtained on contiguous CMR_SAX images in one hand, and to values obtained from transthoracic echocardiography (TTE) in the other hand. For CMR_SAX and TTE, LVEF was computed with Simpson method. Reproducibility of LVEF measurements was additionally determined. The accuracy of volume measurements was assessed against reference aortic stroke volumes obtained by phase-contrast MR imaging.LVEF from CMR_LAX had a mean value of 47 ± 8% and were on average 5% higher than reference LVEF from CMR_SAX (42 ± 8%), closer to routine values from TTE_LAX (49 ± 8%), much better correlated with the reference LVEF from CMR_SAX (R = 0.88) than that from TTE (R = 0.58), obtained with a higher reproducibility than with the 2 other techniques (% of interobserver variability: CMR_LAX 5%, CMR_SAX 11%, and TTE 13%), and obtained with 4-fold lower recording and calculation times than for CMR_SAX. Apart from this, CMR_LAX stroke volume was well correlated with phase-contrast values (R = 0.81).In patients with predominantly regional contractility abnormalities, the determination of LVEF by CMR_LAX is twice more reproducible than the reference CMR_SAX method, even though the LVEF is consistently overestimated compared with CMR_SAX. However, the CMR_LAX LVEF determination provides values closer to TTE measurements, the most available and commonly used method in clinical practice, clinical trials, and guidelines in ischemic cardiomyopathy. Moreover, LVEF determination by CMR_LAX allows a 63% gain of acquisition/reading time compared with CMR_SAX. Thus, despite the fact that LVEF obtained from CMR_SAX remains the gold standard, CMR_LAX should be considered to shorten the overall imaging acquisition and reading time as a putative replacement.     

心肌磁共振显像、核素心肌灌注显像、超声心动图与X线左心室造影测定左心室功能的对比研究

目的:评价心肌磁共振显像(MRI)、核素心肌灌注显像和超声心动图对比X线左心室造影(LVG)检测左心室功能的应用价值。方法:46例患者同期分别行左心室造影、心肌磁共振显像、核素心肌灌注显像(30例)及超声心动图(38例)检查,测定左心室功能。将左心室造影作为标准,与其它3种影像学方法比较,行相关性及一致性分析。结果:心肌磁共振显像与左心室造影所测左心室舒张末期容积、收缩末期容积和射血分数的相关系数分别为0.94、0.98、0.96(P均＜0.001),核素心肌灌注显像与左心室造影的相关系数分别为0.82、0.90、0.93(P均＜0.001),超声心动图与左心室造影的相关系数分别为0.66、0.74、0.69(P均＜0.001)。心肌磁共振显像与左心室造影所测舒张末期容积、收缩末期容积和射血分数一致性范围分别为(-21.4±31.8)ml,(-7.7±25.0)ml,(-2.2±8.8)%。核素心肌灌注显像与左心室造影的一致性范围分别为(-36.8±53.1)ml,(-15.2±32.2)ml,(-2.6±11.0)%。超声心动图与左心室造影的一致性范围分别为(-80.9±95.8)ml,(-47.5±96.0)ml,(3.6±21.1)%。结论:心肌磁共振显像检测心功能准确、可靠,与左心室造影相关性明显,一致性好。核素心肌灌注显像与左心室造影亦具有良好的相关性,但一致性偏差。超声心动图左心功能测值较左心室造影有明显偏倚,一致性差。     

Investigation of Cystic Left Ventricular Masses with Echocardiography and Magnetic Resonance Imaging

We report on two patients who had cystic masses located in the left ventricle associated with findings of congestive heart failure. Both echocardiography and magnetic resonance imaging (MRI) were helpful in identifying features of these masses. Echocardiography was used to guide percutaneous transarterial catheter drainage of the mass in one patient.     

Assessment of Left Ventricular Mass and Hypertrophy by Cardiovascular Magnetic Resonance Imaging in Pediatric Hypertension

Cardiovascular magnetic resonance (CMR) imaging in adults is considered the gold standard for assessment of left ventricular mass (LVM) and left ventricular hypertrophy (LVH). The authors aimed to evaluate agreement of LVM measurements and LVH determination between echocardiography (ECHO) and CMR imaging in children with hypertension (HTN) confirmed by 24‐hour ambulatory blood pressure monitoring (ABPM). The children (n=22) underwent contemporaneous ECHO, CMR imaging, and ABPM. Patients had a mean body mass index of 30.9±7.5 (kg/m²), and 81.8% had severe HTN. LVM measured by ECHO was 189.6±62.1 g and by CMR imaging was 164.6±44.7 g (P<.0001). Bland‐Altman analysis revealed significant variability between ECHO and CMR imaging in the measurement of LVM. Interobserver error was higher with ECHO than with CMR imaging. ECHO had high sensitivity and low specificity in LVH determination. In conclusion, ECHO overestimates LVM and is less accurate in measuring LVM as compared with CMR imaging in children with HTN. Further prospective study using CMR imaging to assess LVM in children is warranted.     

二维超声、实时三维超声和磁共振测量室壁瘤患者左心室容积和功能的对比研究

目的:探讨实时三维超声(RT-3DE)测量冠心病合并左心室室壁瘤患者左心室容积和功能的价值.方法:应用二维超声(2DE)、实时三维超声及磁共振成像(MRI)测量左心室室壁瘤患者手术前后左心室舒张末容积、左心室收缩末容积、左心室射血分数,进行容量测定及功能评价的对比研究.结果:术前二维超声及实时三维超声测得的左心室舒张末容积、左心室收缩末容积均较MRI偏低,左心室射血分数较MRI偏高,差异有统计学意义(P<0.05),术后二维超声测得的左心室舒张末容积、左心室收缩末容积较MRI偏低,差异有统计学意义(P<0.05),实时三维超声测得的左心室舒张末容积、左心室收缩末容积与MRI所测值之间差异无统计学意义.术后二维超声及实时三维超声测得的左心室射血分数差异无统计学意义.结论:实时三维超声测定左心室容量与功能准确可靠,较目前临床普遍采用的二维超声(Simpson's双平面法)测量左心室容积更接近MRI测量值,但在术前室壁瘤患者,所测左心室容积与磁共振相比仍有明显低估.