Contents lists available at ScienceDirect Clinical Imaging journal homepage: www.elsevier.com/locate/clinimag Cardiothoracic Imaging Progression of probable UIP and UIP on HRCT Mary Salvatore a,b, ⁎ , Ayushi Singh a , Rowena Yip a , Esther Fevrier a , Claudia I. Henschke a , David Yankelevitz a , Maria Padilla c a Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America b Department of Radiology, Columbia University Medical Center, New York, NY, United States of America c Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America ARTICLE INFO Keywords: Usual interstitial pneumonitis Chest CT ABSTRACT Purpose: To determine patterns of progression of probable Usual Interstitial Pneumonitis (UIP). Methods: This HIPPA compliant, IRB-approved study draws patients from our Fibrosis Registry. All patients with a consensus diagnosis of Idiopathic Pulmonary Fibrosis (IPF) were included. Most recent CT scans and all earlier CT scans were reviewed to determine the fibrosis grade in each lobe based on probable UIP (pUIP) findings of ground glass opacities, traction bronchiolectasis and reticulations or UIP findings of subpleural basilar pre- dominant fibrosis with honeycombing (HC) and absence of features that would suggest an alternative diagnosis. Results: 103 patients with a working diagnosis of IPF are the focus of this report. Among the 68 with pUIP on the initial CT, 32 (47%) progressed; median time to progression was 51 months. The risk of HC progression, adjusted for gender, of patients with emphysema was 2.53 times higher than patients without emphysema (HR = 2.53, 95% CI: 1.06–6.02). Among the 35 with HC on the initial CT scan, 20 (57%) progressed to more advanced HC; median time to progression was 31 months. Increased pulmonary artery size was significantly associated with an elevated risk for more advanced HC progression (HR = 1.16, 95% CI: 1.04–1.31). Conclusion: Ground glass opacities, traction bronchiolectasis and reticulations, a “Probable UIP Pattern” by ATS criteria progressed to UIP in 47% of patients on follow-up imaging. 1. Background Idiopathic Pulmonary Fibrosis (IPF) has the worst prognosis of all the Idiopathic Interstitial Pneumonias with a mean life expectancy of 3.8 years after diagnosis [1]. The American Thoracic Society (ATS) provides guidelines for the diagnosis of IPF. First there must be no known cause for a patient's lung fibrosis after a thorough clinical eva- luation including serologic studies. Second the patient must have a CT scan showing a “UIP pattern” defined as sub-pleural basilar pre- dominant fibrosis with HC and absence of features that would suggest alternative diagnoses (Fig. 1). If the patient does not have honey- combing but has sub pleural basilar predominant fibrosis they are said to have a “Probable UIP” pattern (pUIP) by ATS criteria and a biopsy may be necessary for diagnosis [2,3](Fig. 2). Until recently the only treatment for IPF was lung transplant which limited the need for identification of early, pre-clinical imaging findings of UIP. In 2014, two new anti-fibrotic medications, Pirfenidone and Nintedanib, were approved in the United States. They target multiple pathways of the fibro-proliferative process of UIP [4]. This stimulated effort to detect IPF in its early, possibly preclinical stage before the advanced disease stage with honeycombing develops. Retrospective review of all earlier CT scans of patients who now have advanced dis- ease that currently meets the ATS criteria for a UIP pattern is a critical first step in identifying early signs of UIP on chest CT. The purpose of our research project is to evaluate the change in IPF related fibrosis over time with particular focus in the transition from “Probable UIP” to “UIP” pattern to better identify early findings. Our goal is to investigate if “Probable UIP” Pattern is an “Early UIP Pattern” and to identify risk factors associated with progression from “Probable UIP” to “UIP”. 2. Methods 2.1. Study design For this retrospective study, data on all patients with a consensus diagnosis of IPF were identified in our Fibrosis Registry. Consent was obtained from all patients according to a HIPAA-compliant, IRB-ap- proved protocol. Between 2014 and 2017, 121 patients were diagnosed with a working diagnosis of IPF based on clinical presentation, CT https://doi.org/10.1016/j.clinimag.2019.07.003 Received 27 March 2019; Received in revised form 14 June 2019; Accepted 9 July 2019 ⁎ Corresponding author at: Columbia University Medical Center, United States of America. E-mail address: ms5680@cumc.columbia.edu (M. Salvatore). Clinical Imaging 58 (2019) 140–144 0899-7071/ © 2019 Published by Elsevier Inc. T