A retrospective study of 3D measurement and analysis applied in the morphological evaluation of achalasia cardia.

Background: Achalasia cardia (AC) is defined as a disorder of esophageal motility whose diagnostic gold standard depends on high-resolution manometry (HRM). The invasiveness of HRM can cause difficulties in diagnosis, treatment, and follow-up for patients with AC. Thus, we aimed to investigate the function of 3D reconstruction and measurement to prove the wide application of this alternative non-invasive approach for AC. Methods: A total of 126 patients with AC and 40 healthy subjects in Tianjin Medical University General Hospital from January 2018 to October 2022 were enrolled in this retrospective study. Chest CT images of these subjects were used to reconstruct the 3D models of the esophagus, stomach, spine, left crus, and right crus. Measurements of esophagus length, volume of esophagus, gastroesophageal insertion angle (His angle), max thickness of esophageal wall, esophagus maximum transverse and longitudinal diameter, esophagus-spine angle, and spine-lower esophageal sphincter (LES) angle were applied based on the models. Results: Retrocardiac esophagus length, volume of esophagus, max thickness of esophageal wall, esophagus maximum transverse and longitudinal diameter, thoracic esophagus-spine angle, and spine-LES angle in the AC group were higher than those in the control group (all P values <0.05). Among the three subtypes of AC, thoracic esophagus length, intra-abdominal LES length, volume of esophagus, His angle, esophagus maximum transverse and longitudinal diameter, and thoracic esophagus-spine angle all presented statistical differences (all P values <0.05). Correlation analysis revealed that manometric types were positively associated with His angle [r=0.196; 95% confidence interval (CI): 0.009, 0.372; P=0.028] but negatively associated with volume of esophagus (r=-0.480; 95% CI: -0.639, -0.310; P<0.001), esophagus maximum transverse diameter (r=-0.551; 95% CI: -0.679, -0.400; P<0.001), esophagus maximum longitudinal diameter (r=-0.518; 95% CI: -0.649, -0.366; P<0.001), and thoracic esophagus-spine angle (r=-0.324; 95% CI: -0.479, -0.157; P<0.001). Conclusions: This study successfully presented the differences in esophageal length, volume, thickness, and angles between healthy subjects and different AC subtypes on the basis of 3D reconstruction and measurement. Thus, 3D model and measurement can be regarded as a good support for further research and make a valuable contribution to developing non-invasive approaches for AC management.