Ultra-low dose CT of the acute abdomen: Spectrum of imaging findings

Transcription

1 Ultra-low dose CT of the acute abdomen: Spectrum of imaging findings Poster No.: C-1452 Congress: ECR 2010 Type: Educational Exhibit Topic: GI Tract Authors: P. A. Vlachou, C. Kloeters, S. Kandel, P. Hein, A. Lembcke, P. Rogalla ; Toronto, ON/CA, Berlin/DE Keywords: acute abdomen, ultra-low dose computed tomography, dose reduction DOI: /ecr2010/C-1452 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 17

2 Learning objectives The purpose of the poster is to: 1. familiarize radiologists with the appearances of non-contrast enhanced ultra-low dose CT (ULD-CT). 2. display image characteristics of ULD-CT and to demonstrate the potential spectrum of imaging findings in patients with acute abdomen. Background Fast and precise diagnosis is crucial for the Emergency Departments and the use of CT scanning has increased over the last few years, particularly in the evaluation of patients presenting with an acute abdomen. Page 2 of 17

3 Fig.: Change in CT examination frequency and proportion of radiation between 1996 and References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA CT is a highly sensitive, fast and reproducible imaging modality which is superior to the abdominal radiograph. However, the associated radiation dose is a major concern particularly in patients presenting with recurrent symptoms (for example patients prone to formation of urinary tract calculi or patients with recurrent abdominal adhesion symptoms). Page 3 of 17

4 Fig.: Overview: effective doses References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA ULD-CT combines the advantages of conventional radiographs and those of CT by providing reduced radiation dose and adds the benefit of additional morphological information of axial imaging. Images for this section: Page 4 of 17

5 Fig. 1: Change in CT examination frequency and proportion of radiation between 1996 and Fig. 2: Overview: effective doses Page 5 of 17

6 Imaging findings OR Procedure details During a three month period, 54 consecutive patients who presented to the emergency room with acute abdominal pain underwent ULD-CT. Three indications were accepted for performing ULD-CT of the abdomen: rule out bowel obstruction rule out viscus perforation rule out urolithiasis Confirmation of the final diagnosis was made with surgery, biopsy, stone extraction, standard-dose CT, laboratory values and medical record review. All patients were scanned using 16 or 64 slice CT (Aquilion, Toshiba). The scanning parameters were 120 kv, ma. Thin slices of 0.5 mm and thicker slices of 5 mm were reconstructed from every data set. Axial, coronal and sagittal reconstructions were obtained. No scout views were obtained. No iintravenous, oral or rectal contrast material was used. The effective dose range was 0.3 to 0.9 msv, equivalent to that of a plain abdominal radiograph. A three view acute abdominal series (which includes erect chest x-ray, supine and upright abdominal x-ray) have estimated effective dose ranging from 1.5 to 2.4 msv. Case 1: 55 year-old patient presented with abdominal distension and pain. ULD-CT shows small bowel obstruction secondary to adhesions in the right lower quadrant (red circle). The diagnosis was confirmed at surgery (black arrow). Page 6 of 17

7 Fig.: Adhesional small bowel obstruction. Axial/coronal ULD-CT and correlation with intra-operative findings. References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Case 2: 61 year-old patient with generalised abdominal pain. ULD-CT showed peri-hepatic free air (red circle) and free fluid. The patient also underwent contrast-enhanced standard dose CT of the abdomen and pelvis which did not provide additional information. Both CTs demonstrated hollow organ perforation and the diagnosis was confirmed at surgery. Page 7 of 17

8 Fig.: Perforated intra-abdominal viscus. Comparison of axial ULD-CT (top row) and axial standard dose CT (bottom row). References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Page 8 of 17

9 Fig.: Perforated intra-abdominal viscus. Correlation of CT and intra-operative findings. References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Case 3: 54 year-old patient presented with left sided colicky pain. ULD-CT ahowed a small left UVJ calculus. Follow-up was performed with ultrasound one day later. Fig.: Left UVJ calculus. Ultrasound and axial/coronal ULD-CT images. References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Case 4: 35 year-old male presented with epigastric pain. Plain abdominal radiograph was nonspecific. ULD-CT showed swollen pancreas with peripancreatic fluid fluid, in keeping with acute pancreatitis. The patient subsequently underwent contrast enhanced standard dose CT to look for complications of pancreatitis. Page 9 of 17

10 Fig.: Acute pancreatitis. Abdominal radiograph, axial ULD-CT (top right)as well as contrast-enhanced standard dose CT (bottom right) of the abdomen. References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Case 5: 60 year-old patient with lower abdominal pain. CT imaging shows an inflammed appendix with surrounding stranding in keeping with acute appendicitis. The patient underwent appendicectomy which confirmed the diagnosis. Page 10 of 17

11 Fig.: Acute appendicitis. Coronal ULD-CT (top left) and coronal standard dose contrast-enhanced CT (bottom left) with pathological correlation. References: P. A. Vlachou; Department of Medical Imaging, University of Toronto, Toronto, CANADA Images for this section: Page 11 of 17

12 Fig. 1: Adhesional small bowel obstruction. Axial/coronal ULD-CT and correlation with intra-operative findings. Page 12 of 17

13 Fig. 2: Perforated intra-abdominal viscus. Comparison of axial ULD-CT (top row) and axial standard dose CT (bottom row). Fig. 3: Perforated intra-abdominal viscus. Correlation of CT and intra-operative findings. Page 13 of 17

14 Fig. 4: Left UVJ calculus. Ultrasound and axial/coronal ULD-CT images. Page 14 of 17

15 Fig. 5: Acute pancreatitis. Abdominal radiograph, axial ULD-CT (top right)as well as contrast-enhanced standard dose CT (bottom right) of the abdomen. Fig. 6: Acute appendicitis. Coronal ULD-CT (top left) and coronal standard dose contrastenhanced CT (bottom left) with pathological correlation. Page 15 of 17

16 Conclusion Ultra-low-dose abdominal CT: delivers diagnostic information despite a radiation dose profile compatible with conventional X-ray. can be read without specific training in low-dose CT imaging. Personal Information Vlachou Paraskevi, Christian Kloeters, Sonja Kandel, Patrick Hein, Alexander 2 Lembcke, Patrik Rogalla 1 1 Department of Medical Imaging, University Health Network, Toronto, Canada 2 Department of Radiology, Charité - University Hospital Berlin, Berlin, Germany Toronto General Hospital 585 University Ave Toronto, ON M5G 2N2 Canada paraskevi.vlachou@uhn.on.ca Tel: ext Fax: Page 16 of 17

17 References Udayasankar UK, Li J, Baumgarten DA, Small WC, Kalra MK. Acute abdominal pain: value of non-contrast enhanced ultra-low-dose multi-detector row CT as a substitute for abdominal radiographs. Emerg Radiol. Jan 2009;16(1): Wall BF, Hart D. Revised radiation doses for typical X-ray examinations. Report on a recent review of doses to patients from medical X-ray examinations in the UK by NRPB. National Radiological Protection Board. Br J Radiol. May 1997;70(833): Yanch JC, Behrman RH, Hendricks MJ, McCall JH. Increased radiation dose to overweight and obese patients from radiographic examinations. Radiology. Jul 2009;252(1): Rogalla P, Kluner C, Taupitz M. [Ultra-low-dose CT to search for stones in kidneys and collecting system]. Aktuelle Urol. Aug 2004;35(4): Kluner C, Hein PA, Gralla O, et al. Does ultra-low-dose CT with a radiation dose equivalent to that of KUB suffice to detect renal and ureteral calculi? J Comput Assist Tomogr. Jan-Feb 2006;30(1): Page 17 of 17