Lung-RADS 0: How much is too much?

In 2022, Lung-RADS introduced a "Lung-RADS 0" category for CT findings suggestive of acute infectious or inflammatory processes. This study aimed to evaluate thoracic radiologist agreement with Lung-RADS 0 assignments and assess outcomes on follow up imaging. This retrospective review was conducted on lung cancer screening CT scans from November 2022 to July 2025. LungView (LungView, Fulton, MD, USA) software identified scans assigned Lung-RADS 0. Cases without follow-up were excluded. Thoracic radiologists reviewed the CT scans for agreement with Lung-RADS 0 and reclassified those with disagreements. Follow-up scans were assessed for resolution or progression of findings. Out of 4020 CT scans, 135 were categorized as Lung-RADS 0 (3.3%). After excluding 6 cases with no follow-up, 129 scans and their clinical reports were analyzed and reviewed independently by board certified radiologists within the thoracic division. The reviewers felt that 26.4% of the studies should have been originally reported as Lung RADS 2, 3 or 4, with the remainder (73.6%) deemed appropriately reported as Lung RADS 0. Resolution or improvement of findings occurred in 79/129 cases (61.2%), while 33.3% showed no change or worsening. Two malignancies were diagnosed at follow-up, neither of which was delayed due to the Lung-RADS 0 classification. This study highlights the need for consistent and correct application of Lung-RADS 0 category defined by ACR to avoid unnecessary shorter-term follow-ups. There was no delayed diagnosis of malignancy for those patients with nodules assigned as Lung RADS 0.