Relationship between cardiac MR compression classification and CT chest wall indexes in patients with pectus excavatum

Abstract

Background/purpose: In pectus excavatum (PE) patients owing to the location of the heart in the chest cavity, the most affected site of compression by the depressed chest wall is the right heart, and surgical repair has shown to provide a significant relief in the RH cavities compression. Our aim was to explore the relationship between the site of right cardiac compression, chest wall indexes (CT-CWI) and the sternal torsion angle (STA) based on cardiac magnetic resonance (CMR) and computed tomography (CT) among PE patients. Methods: We included PE patients with no previous surgical correction referred to CMR and chest CT imaging as presurgical evaluations. The following CT-CWI were calculated: Haller Index (HI), correction index (CI) and STA. A CMR compression classification (CMR-CC) was implemented based on the analysis (in the horizontal long axis plane at end of diastole) of the right cardiac compression site, caused by the thoracic cage (sternum/ribs): Type 0 (T0): absence of cardiac compression; Type 1 (T1): compression of the lateral wall of the right ventricle (RV) without involvement of the atrioventricular (AV) groove; Type 2 (T2): compression of the RV involving the AV groove. Results: Sixty PE patients underwent CMR and chest CT. Fifty (81%) patients were male, and the median age was 17.5 (14.0; 23.0) years. T0, T1 and T2 were found in 14 (23%), 27 (45%) and 19 (32%) patients. There were significant differences between types with regard to the HI (T0 3.9 ± 1.1, T1 4.8 ± 2.0, T2 6.4 ± 3.1, p < 0.009) and to the CI (T0 22.1 ± 10.4%, T1 31.6 ± 16.1%, T2 46.9 ± 16.3% p < 0.0001) and STA (T0 9.1 ± 7.9°, T1 12.7 ± 10.3°, class T2 23.0 ± 13.6°p = 0.001) respectively. Conclusion: In this study, we established a cardiac magnetic resonance compression classification of patients with pectus excavatum comprising a simple discrimination of cardiac compression sites, which were related to chest wall indexes.