The impact of severe obesity on image quality and ventricular function assessment in echocardiography and cardiac MRI

Abstract

This study sought to evaluate the impact of severe obesity on image quality and ventricular function assessment in cardiovascular magnetic resonance (MRI) and trans-thoracic echocardiography (TTE). We studied 100 consecutive patients who underwent clinically indicated cardiac MRI and TTE studies within 12 months between July 2017 and December 2020; 50 (28 females and 22 males; 54.5 ± 18.7 years) with normal body mass index (BMI) (18.5-25 kg/m²) and 50 (21 females and 29 males; 47.2 ± 13.3 years) with severe obesity (BMI ≥ 40 kg/m²). MRI and TTE image quality scores were compared within and across cohorts using a linear mixed model. Categorical left (LVF) and right (RVF) ventricular function were compared using Cohens Kappa statistic. Mean BMI for normal weight and obese cohorts were 22.2 ± 1.7 kg/m² and 50.3 ± 5.9 kg/m², respectively. Out of a possible 93 points, mean MRI image quality score was 91.5 ± 2.5 for patients with normal BMI, and 88.4 ± 5.5 for patients with severe obesity; least square (LS) mean difference 3.1, p = 0.460. TTE scores were 64.2 ± 13.6 for patients with normal BMI and 46.0 ± 12.9 for patients with severe obesity, LS mean difference 18.2, p < 0.001. Ventricular function agreement between modalities was worse in the obese cohort for both LVF (72% vs 80% agreement; kappa 0.53 vs 0.70, obese vs. normal BMI), and RVF (58% vs 72% agreement, kappa 0.18 vs 0.34, obese vs. normal BMI). Severe obesity had limited impact on cardiac MRI image quality, while obesity significantly degraded TTE image quality and ventricular function agreement with MRI.

Keywords: Cardiac MRI; Echocardiography; Image quality; Severe obesity.

Fig. 1

Cardiac MRI image quality assessment list. Image quality scoresheet used for cardiac MRI outlining the 31-part list of routine imaging categories. Higher scores indicate higher level of quality for a maximum total possible score of 93 points. Note the additional, separately-scored tissue characterization for MRI

Fig. 2

TTE image quality assessment list. Image quality scoresheet used for TTE outlining the 31-part list of routine imaging categories. Higher scores indicate higher level of quality for a maximum total possible score of 93 points

Fig. 3

Average image quality score by modality and BMI. A shows overall image quality scores, B shows valve image quality scores, C shows vessel image quality scores, while Panel D shows chamber image quality scores

Fig. 4

Average ventricular image quality score by modality and BMI. A shows left ventricular image quality scores while B shows right ventricular image quality scores

Fig. 5

A Example of low overall echocardiography image quality score. Top (left to right) – 4 chamber TTE views without, with microbubble contrast, MRI steady state free precession cine. Bottom: 2 chamber TTE views without, with microbubble contrast, MRI steady state free precession cine. Overall image quality score: TTE – 21; MRI – 91. TTE transthoracic echocardiography, MRI magnetic resonance imaging. BMI 49.2. B Example of low overall cardiac magnetic resonance image quality score. Top (left to right) – 4 chamber MRI steady state free precession cine, TTE view without, with microbubble contrast. Bottom: 2 chamber MRI steady state free precession cine, TTE view without, with microbubble contrast. Overall image quality score: MRI – 71; TTE – 43.5. TTE transthoracic echocardiography, MRI magnetic resonance imaging. BMI = 56.5

Fig. 6

TTE and cardiac MRI categorical ventricular function agreement by BMI class. A Agreement between cardiac MRI and TTE LV function categories by BMI class. B Agreement between cardiac MRI and TTE RV function categories. By BMI class. BMI body mass index, N-OB non-obese, OB obese.