Imaging and Radiation Research (2019) Volume 2 Issue 1 doi:10.24294/irr.v2i1.1716 11 Review Article Initial approach to mediastinal alterations: Review of their radio- graphic anatomical references Emmanuel Salinas Miranda * , Luisa Karen Cifuentes, Juan Gonzalo Vélez, Bibiana Andrea Pinzón Departamento de Radiología, Hospital universitario Fundación Santa Fe de Bogotá, Bogotá, DC, Colombia. E-mail: emmanuels7@gmail.com ABSTRACT The suspicion of mediastinal alterations, always includes in its initial study, the chest radiography. The iden- tification of mediastinal alterations in the X-ray is a priority. The knowledge of the mediastinal references and the iden- tification of their alterations allows the suspicion of a pathology specific to each of the mediastinal spaces. When the semiology of mediastinal lesions, their location and the three most frequent pathologies are taken into account, the pos- sibility of having an etiological diagnosis increases [1] . This is a review article based on a detailed literature search, in which radiological mediastinal references are studied, with emphasis on the epidemiological data of each one of them. Keywords: Epidemiology; Surgery; Radiography; Tumors; Evidence-based Medicine ARTICLE INFO Received: 1 April 2019 Accepted: 28 May 2019 Available online: 2 June 2019 COPYRIGHT Copyright © 2019 by author(s). Imaging and Radiation Research is pub- lished by EnPress Publisher LLC. This work is licensed under the Creative Com- mons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0). https://creativecommons.org/licenses/by-nc/ 4.0/ 1. Introduction The mediastinum is an intrathoracic extra-pleural anatomical compartment, located in the center of the thorax, between both lungs, behind the sternum and the chondrocostal junctions and in front of the vertebral bodies and ribs. In its inferior aspect, it is limited by the diaphragm muscle, and in its superior aspect by the cervicothoracic strait. In chest radiography, mediastinal landmarks may be the product of the continuity of mediastinal, pulmonary or vertebral structures when they are tangentially traversed by the x-ray beam or they may be a visu- al effect such as the Mach bands discussed later. These silhouettes can be divided into lines, bands or interfaces [1,2] (Figure 1). The absence, thickening or displacement of one or more of the mediastinal lines, bands or interfaces may signify a mediastinal injury; however, the technical conditions of the radiograph and anatomical variations also modificate the frequency and the way in which these mediastinal silhouettes or their alterations are observed. The most fre- quently visualized lines are the paratracheal band and the paraspinal line on the right side [2] . The rest of the mediastinal landmarks are visu- alized in varying percentages in the chest radiograph (Table 1). The first step in approaching mediastinal masses on chest radiog- raphy is to suspect their mediastinal origin. The radiographic features of a lesion that point to a mediastinal origin are: the intimate relationship of the mass with the mediastinal structures, smooth and sharp margins, and the formation of obtuse angles between the mass and the lung field [1,3] (Figure 2).