REVIEWS AND COMMENTARY n REVIEW Radiology: Volume 279: Number 2—May 2016 n radiology.rsna.org 329 1 From the Departments of Radiology (E.P., L.M.M.B., M.G.M.H.) and Medical Informatics (J.A.K.), Erasmus Medical Center, PO Box 2040, 3000 CA Rotterdam, the Netherlands. Received December 19, 2014; revision requested January 16, 2015; final revision received March 31; accepted April 13; final version accepted April 24; final review December 14. Supported by the Open Technology Programme of Technology Foundation STW. Address correspondence to E.P. (e-mail: e.pons@erasmusmc.nl). q RSNA, 2016 Radiological reporting has generated large quantities of digital content within the electronic health record, which is potentially a valuable source of information for im- proving clinical care and supporting research. Although radiology reports are stored for communication and documentation of diagnostic imaging, harnessing their potential requires efficient and automated information ex- traction: they exist mainly as free-text clinical narrative, from which it is a major challenge to obtain structured data. Natural language processing (NLP) provides tech- niques that aid the conversion of text into a structured representation, and thus enables computers to derive meaning from human (ie, natural language) input. Used on radiology reports, NLP techniques enable automatic identification and extraction of information. By exploring the various purposes for their use, this review examines how radiology benefits from NLP. A systematic literature search identified 67 relevant publications describing NLP methods that support practical applications in radiology. This review takes a close look at the individual studies in terms of tasks (ie, the extracted information), the NLP methodology and tools used, and their application pur- pose and performance results. Additionally, limitations, future challenges, and requirements for advancing NLP in radiology will be discussed. q RSNA, 2016 Online supplemental material is available for this article. Ewoud Pons, MD Loes M. M. Braun, MD, PhD M. G. Myriam Hunink, MD, PhD Jan A. Kors, PhD Natural Language Processing in Radiology: A Systematic Review 1 This copy is for personal use only. To order printed copies, contact reprints@rsna.org