All CT studies were obtained at Mount Sinai Hospital, in General Electric® or Siemens® multidetector row chest CT scanners. Chest CT studies were performed using an institutional clinical protocol12 (link) with a radiation dose at 120 kVp, and a mean of 146 (SD 69) mAs, with subjects in the supine position, noise correction, and routine periodic scanner calibration. CT scans were obtained from the lung apices to the bases in a single breath hold at maximum inspiration, and we excluded those with section thicknesses exceeding 1.5 mm, contrast administration, or respiratory or motion artifacts. All deidentified and coded chest CT images were stored and cataloged during the past 5 years in the WTC PEU Chest CT Image Archive (ClinicalTrials.gov identifier NCT03295279).5 (link)