Quantitative imaging features of pulmonary artery involvement in Takayasu arteritis on computed tomography pulmonary angiography in patients with and without pulmonary hypertension.

BACKGROUND: Pulmonary artery involvement (PAI) in Takayasu arteritis (TA) is often diagnosed late and may lead to pulmonary hypertension (PH). Quantitative imaging biomarkers that could aid early detection are currently lacking. This study aimed to quantify pulmonary arterial volumes (PAVs) in TA-PAI using computed tomography pulmonary angiography (CTPA) and to compare imaging features between PAI patients and age-/sex-matched controls, as well as between PAI subgroups with and without PH. METHODS: This single-center retrospective study (April 2022-March 2024) included 90 patients [median age 33 years; interquartile range (IQR), 27-43 years; 91.1% female] meeting modified Ishikawa criteria and 47 age- and sex-matched controls with normal pulmonary arteries on CTPA. PAVs were measured in six non-overlapping diameter (D) strata (D ≤0.8, 0.8< D ≤1.6, 1.6< D ≤2.4, 2.4< D ≤3.2, 3.2< D ≤4.0, D >4.0 mm) using a deep learning-based segmentation method implemented on the AZE Virtual Place workstation. Cumulative threshold-based volumes and the proportional contribution of each stratum to total intraparenchymal PAV were then analyzed. Qualitative features (stenosis, occlusion, dilation, aneurysm, wall thickening, thrombosis) were recorded. PH was defined by echocardiography according to the European Society of Cardiology/European Respiratory Society (ESC/ERS) PH guidelines. Continuous variables were compared using the t-test or Mann-Whitney U test, and categorical variables using the χ2 or Fisher's exact test, with Bonferroni correction (P<0.05). RESULTS: Compared with the control group, the patient group showed significantly lower cumulative volumes (mL) for arteries with diameters of ≤3.2 mm [52.8 (IQR, 45.8-57.7) vs. 56.6±11.2 mL; P=0.047] and ≤4.0 mm [59.5 (IQR, 52.2-65.0) vs. 63.7±11.6 mL; P=0.028]. The proportional contribution of each non-overlapping diameter stratum to total intraparenchymal PAV was lower in patients than in controls for the 1.6< D ≤2.4 mm (patients vs. controls: 26.1%±5.5% vs. 28.6%±6.3%; P=0.021) and 2.4< D ≤3.2 mm (21.6%±3.5% vs. 23.6%±3.4%; P=0.001). Compared with non-PH patients (n=73), the PH subgroup (n=17) had larger main pulmonary artery diameters (32.3±5.4 vs. 26.9±5.3 mm; P<0.001) and higher rates of stenosis (88% vs. 63%; P=0.045), dilation (71% vs. 29%; P=0.001), and aneurysm (24% vs. 4%; P=0.007), but cumulative PAVs did not differ significantly. CONCLUSIONS: CTPA-based PAV quantification reveals marked volume loss in mid-sized pulmonary arteries in TA-PAI. PAV might be beneficial for detecting TA. However, PAV showed no significant difference between groups according to PH status, despite severe pulmonary arterial structural changes.