Nicola Schieda MD, Presenter: Nothing to Disclose

Wael M. Shabana MD, Abstract Co-Author: Nothing to Disclose

Najla Fasih MBBS, Abstract Co-Author: Nothing to Disclose

MDCT angiography in acute mesenteric ischemia (AMI) employs a triphasic protocol.  The purpose of this study is to evaluate the diagnostic yield of the unenhanced phase and to determine if a standard portal venous phase is sufficient to evaluate the splanchnic arterial vasculature. Elimination of one or both of these phases when studying AMI, would result in substantial dose reduction in a pre-selected (young) patient population.

Patients from August 2007 – July 2009 evaluated consecutively with MDCT to exclude AMI were collected; 218 patients met the inclusion criteria. Diagnostic gold standard was obtained from surgical/endoscoping findings and pathological reports. 52 patients have proven AMI and 166 patients have negative clinical outcomes. 40 patients were randomly selected from each group. 3 blinded abdominal imagers reviewed the studies. The first reader reviewed the standard triphasic MDCT examination, while the second reviewed the unenhanced and portal venous phases only. The third reader reviewed the portal venous acquisition. Diagnostic accuracy was compared between readers.    

The sensitivity of submucosal hemorrhage is 10% and the specificity 98%. In all true positive cases, there are other CT findings detected by all readers to correctly diagnose AMI. The sensitivity of abnormal enhancement ranges from 49-77% and the specificity 83-88%. There is no statistical difference in diagnostic accuracy between the readers. The sensitivity of SMA thrombosis or occlusion ranges from 23-28% and the specificity 95-100%. There is no statistical difference in diagnostic accuracy when assessing SMA, Celiac or IMA pathology between readers or in comparison  to a consensus reading.   

The unenhanced phase could have been safely omitted in this study without compromising the diagnostic accuracy of the examination. Bowel enhancement is adequately assessed without an unenhanced phase. The sensitivity of submucosal hemorrhage is 10%. All true positive cases have other CT findings present to make the diagnosis of AMI.  The portal venous phase was sufficient to diagnose major mesenteric arterial pathologies with no difference in diagnostic accuracy when to compared to the CT angiogram.     

Elimination of the unenhanced phase and CT angiogram from a triphasic MDCT protocol in young patients can reduce dose without compromising diagnostic accuracy of the examination.

Schieda, N, Shabana, W, Fasih, N, Multidetector CT Evaluation of Acute Mesenteric Ischemia: Diagnostic Accuracy and Appraisal of MDCT Angiography‚Is a Triphasic Examination Currently Justifiable?.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005645.html