Evaluation of computed tomography in the diagnosis of ultrasound-proven diaphragm dysfunction

Abstract Introduction: Computed tomography (CT) is routinely performed to assess dyspnea, but few data are evaluating diaphragmatic muscle using CT. This study aimed to assess CT in the diagnosis of diaphragmatic dysfunction. Methods: We retrospectively collected diaphragmatic ultrasounds performed between 2018 and 2021 at our center (Marseille, France). We measured diaphragmatic pillars on CT at the level of L1 and the celiac artery, as well as the difference in height between the two diaphragmatic domes in diaphragmatic dysfunctions and controls, and compared with ultrasound measurements. Results: 65 patients were included, 24 with diaphragmatic paralysis, 13 with diaphragmatic weakness, and 28 controls. The CT thickness of the pillars in the case group (paralysis and weakness) of left dysfunctions (n=24) was significantly thinner at the level of L1 and the celiac artery compared with controls (2.0mm vs. 7.4mm and 1.8mm vs. 3.1mm, p<0.001 respectively), and significantly different for paralysis (and not weakness) when right dysfunction (n=15) (2.6mm vs. 7.4mm and 2.2mm vs. 3.8mm, p<0.001 respectively for paralysis vs controls). Whatever the side of dysfunction, there was a significant difference in diaphragmatic height between cases and controls (7.70cm vs. 1.16cm and 5.51cm vs. 1.16cm, p<0.001 right and left dysfunction respectively). The threshold values (ROC curve analyses) for height differences between the two domes in favor of paralysis or weakness on the right dysfunctions were 4.44cm and 3.51cm respectively; and 2.70cm and 2.48cm on the left dysfunctions respectively, with good performances. Conclusion:The thickness of the pillars on CT was thinner in left diaphragmatic dysfunction and in paralysis in right diaphragmatic dysfunction. An increase in the difference in the diaphragmatic height may strongly identify diaphragmatic dysfunction with precise thresholds.