PubMedCurrent medical imaging2026-11-11
Discordance Between Interferon-Gamma Release Assay Positivity and Thoracic CT Findings: A Real-World Evaluation of Pre-Immunosuppression Screening.
Köksal Murathan M, Aslan Muhammet Ahmet MA, Alçın Eda Şener EŞ, Altunsoy Adalet A et al.
Interferon-Gamma Release Assay (IGRA) is a primary tool for latent Tuberculosis (TB) screening, but its radiological correlation in endemic regions requires further clarification. We aimed to evaluate the relationship between IGRA status and thoracic Computed Tomography (CT) findings in candidates for immunosuppression.
This retrospective observational study analyzed 91 adult patients (51 IGRA-positive, 40 IGRA-negative) evaluated between January 2020 and December 2023. Given the real-world design, CT indications differed between groups, reflecting routine clinical practice: IGRA-positive candidates underwent CT as routine pre-immunosuppression screening, whereas IGRA-negative candidates underwent CT based on clinical suspicion, respiratory symptoms, or elevated inflammatory markers. All thoracic CT scans were performed within 4 weeks of IGRA testing and prior to biological therapy initiation. Two blinded radiologists evaluated 14 specific CT patterns. Associations between imaging features and IGRA status were analyzed using univariable comparisons, multiple comparison corrections, and composite endpoints.
Marked operational discordance was observed; IGRA positivity did not correlate with typical TB-associated CT findings. Findings suggestive of prior granulomatous infection-specifically calcified lymph nodes (20.0% vs. 2.0%, p=0.009), splenic calcifications (20.0% vs. 5.9%, p=0.045), and hepatic calcifications (15.0% vs. 2.0%, p=0.04)-were more prevalent in the IGRA-negative group; however, individual parenchymal calcifications did not survive strict multiple testing Bonferroni correction (adjusted threshold α=0.0036). Composite TB-like findings (TB_combo) were significantly less frequent in IGRA-positive patients (21.6% vs. 52.5%; OR = 0.25, 95% CI: 0.10-0.63, p=0.003), largely reflecting indication bias. Notably, 53.8% of IGRA-positive patients with normal CT scans received prophylactic treatment, indicating that management decisions were primarily guided by immunological results rather than radiological findings.
In this endemic setting, IGRA results showed limited concordance with thoracic CT findings, reflecting the substantial impact of clinical indication bias in real-world practice. These findings demonstrate that immunological signals and radiological evidence frequently diverge during preimmunosuppression screening.
This study demonstrates a marked operational discordance between IGRA status and thoracic CT findings during pre-immunosuppressive screening in an endemic region, largely driven by indication bias. Our results highlight the need for prospective outcome-based studies before modifying current risk stratification and chemoprophylaxis protocols.