Retrospective Analysis of Emergency Computed Tomography Imaging Utilization at an Academic Centre: An Analysis of Clinical Indications and Outcomes  Jason Seidel, BSc, MD, Mary Beth Bissell, MSc, MD, Sannihita Vatturi, Angus Hartery, MD, FRCPC  Canadian Association of Radiologists Journal  Volume 70, Issue 1, Pages 13-22 (February 2019) DOI: 10.1016/j.carj.2018.10.004 Copyright © 2018 Canadian Association of Radiologists Terms and Conditions

Figure 1 Computed tomography (CT) imaging over a 1-year time frame by body part. The number of scans is depicted on the y-axis with total number of CT scans followed by the number of CT scans for each body part. The total number of CT scans performed over a one-year period was 4556. Of this, 2107 (46%) head CTs, 1303 CTs of the abdomen (29%), 468 (10%) chest, 408 (9%) CTs of the neck/spine and 101 (2%) CTs of the extremity were performed. Canadian Association of Radiologists Journal 2019 70, 13-22DOI: (10.1016/j.carj.2018.10.004) Copyright © 2018 Canadian Association of Radiologists Terms and Conditions

Figure 2 Emergent computed tomography (CT) imaging of the head stratified by clinical indication with final imaging interpretations by the reporting radiologist. Sankey diagram depicts the relative proportions of reported diagnostic indications for CT imaging of the head and relative proportions of the various clinical outcomes. (1) Any focal neurological deficit, as well as any query for stroke, haemorrhage, or malignancy in the brain. (2) No imaging finding to account for the clinical presentation. (3) Acute or sub-acute ischemic stroke. (4) Intracranial haemorrhage including subarachnoid haemorrhage, epidural haemorrhage, acute and sub-acute subdural haemorrhage. (5) Abscess, acute mastoiditis, chronic mastoiditis, mastoiditis, osteomyelitis, pre-orbital cellulitis. (6) All other pathologies which may explain the presenting symptoms including herpes encephalitis, dural venous sinus thrombosis, hydrocephalus NYD, Chiari I malformation, aneurysm. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2019 70, 13-22DOI: (10.1016/j.carj.2018.10.004) Copyright © 2018 Canadian Association of Radiologists Terms and Conditions

Figure 3 Emergent computed tomography (CT) imaging of the abdomen stratified by clinical indication with final imaging interpretations by the reporting radiologist. Sankey diagram depicts the relative proportions of reported diagnostic indications for CT imaging of the abdomen and relative proportions of the various clinical outcomes. (1) Any requests to rule out abscess or intra-abdominal collection. (2) Small or large bowel obstruction, cecal or sigmoid volvulus. (3) Abdominal pain with no specified location or clinical indication of diffuse or vague abdominal pain. (4) Pain localized to the right lower quadrant or indication of rule out appendicitis. (5) Pain localized to the right or left upper quadrants or epigastric pain, all studies investigating pancreatitis or complications of pancreatitis. (6) Any query for a vascular disorder, including abdominal aortic aneurysms, dissections, thrombosis, mesenteric ischemia, or gastrointestinal bleeding, retroperitoneal hematoma. (7) Epiploic appendagitits, omental infarct, pancreatitis, non-specific free fluid. (8) Acute or chronic cholecystitis, biliary obstruction, hepatitis. (9) Ruptured abdominal aortic aneurysm, mesenteric ischemia. (10) Ruptured ovarian cysts. (11) No findings to account for the presenting symptoms; however, incidental findings require further imaging evaluation. (12) Pyelonephritis or cystitis. (13) Pneumonia, air space disease. (14) Fracture, disk bugle or severe degenerative disk disease. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2019 70, 13-22DOI: (10.1016/j.carj.2018.10.004) Copyright © 2018 Canadian Association of Radiologists Terms and Conditions

Figure 4 Emergent computed tomography (CT) imaging of the chest stratified by clinical indication, with final imaging interpretations by the reporting radiologist. Sankey diagram depicts the relative proportions of reported diagnostic indications for CT imaging of the chest and relative proportions of the various clinical outcomes. (1) Any indication for chest pain, shortness of breath, and queried lung disease, such as pneumonia, chronic obstructive pulmonary disease, or obstructive lung diseases. All investigations of pulmonary embolus. (2) Any indication listed as a trauma or suggestive of such (such as motor vehicle accident, fall, assaults, etc). (3) Pleural effusions and congestive heart failure, pulmonary fibrosis, and abdominal pathologies, such as small bowel obstructions. (4) Thoracic aorta dissection, investigation of hemoptysis. (5) Small bowel obstruction, pulmonary fibrosis, pleural effusion. (6) Soft tissue injury, fracture, pulmonary contusion or laceration, pneumothorax, pneumomediastinum. (7) Thoracic aorta dissection, pulmonary embolus, both acute and chronic. (8) No findings to account for the presenting symptoms; however, incidental findings requiring further imaging evaluation. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2019 70, 13-22DOI: (10.1016/j.carj.2018.10.004) Copyright © 2018 Canadian Association of Radiologists Terms and Conditions

Figure 5 Emergent computed tomography (CT) imaging of the neck and spine stratified by clinical indication with final imaging interpretations by the reporting radiologist. Sankey diagram depicts the relative proportions of reported diagnostic indications for CT imaging of the neck and spine and relative proportions of the various clinical outcomes. (1) Any focal neurological deficit, as well as any query for rule out dissection. (2) No imaging finding to account for the clinical presentation. (3) Degenerative disc disease that may cause presenting symptoms. (4) Deep space neck infection, abscess, peritonsilar abscess, epiglottitis, discitis. (6) All other pathologies which may explain the presenting symptoms including shunt failure and calcific tendonitis of the longus coli muscle. This figure is available in colour online at http://carjonline.org/. Canadian Association of Radiologists Journal 2019 70, 13-22DOI: (10.1016/j.carj.2018.10.004) Copyright © 2018 Canadian Association of Radiologists Terms and Conditions