A combination of C-arm computed tomography (CACT) with conventional digital subtraction angiography (DSA) of the pulmonary arteries can enhance the diagnostic work-up of patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH) by providing a more comprehensive evaluation of the pulmonary arteries, study results published in the Academy of Radiology suggest.

A total of 301 consecutive patients with suspected CTEPH who underwent pulmonary artery angiographies were enrolled in this study. Both DSA and CACT were used to evaluate the pulmonary artery segments and their subsegmental branching, and the diagnostic findings from the work-up were compared. Investigators created a standard of reference, which consisted of information from CACT and DSA and based on CACT consensus and DSA consensus.

In total, there were 5719 pulmonary segments that were evaluated in the 301 patients (age, 64.9±14.1 years) between April 2014 and December 2019. There were 28 (0.4%) segments rated by 2 readers as nondiagnostic on both CACT and DSA. A total of 5640 (98.6%) pulmonary segments were rated to be diagnostic in DSA vs 5600 (97.9%) pulmonary segments were rated to be diagnostic in CACT.

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Motion artifacts on both CACT and DSA represented the main cause of nondiagnostic image quality. There was excellent interobserver agreement for DSA (Κ=0.9) and CACT (Κ =0.91) as well as substantial intermodality agreement between both readers (Κ=0.69 and Κ=0.77, respectively). The intermodality agreement for CACT was excellent compared with standard of reference (Κ=0.96). Meanwhile, the intermodality agreement was “substantial” for DSA compared with standard reference (Κ=0.75), which the investigators suggested was because of the higher number of pathologic findings in CACT that were read as normal in DSA.

A potential limitation of using CACT for pulmonary arteries, according to the researchers, is its invasiveness, particularly compared to CT pulmonary angiography.

The study investigators concluded that a “combination of CACT and DSA can minimize the portion of non-diagnostic examinations, therefore being a reasonable combination to optimize the diagnostic work-up.”


Maschke SK, Werncke T, Becker LS, et al. The value of C-arm computed tomography in addition to conventional digital subtraction angiography in the diagnostic work-up of patients with suspected chronic thromboembolic pulmonary hypertension: an update of 300 patients. Acad Radiol. Published online August 5, 2020. doi:10.1016/j.acra.2020.06.039