Andrew Lovy, Presenter: Nothing to Disclose

Eran Bellin, Abstract Co-Author: Nothing to Disclose

David S. Esses MD, Abstract Co-Author: Nothing to Disclose

Jeffrey Michael Levsky MD, PhD, Abstract Co-Author: Nothing to Disclose

Linda B. Haramati MD, Abstract Co-Author: Investor, OrthoSpace Ltd Investor, Kryon Systems Ltd Spouse, Board Member, BioProtect, Ltd Spouse, Board Member, OrthoSpace, Ltd Spouse, Board Member, Kryon Systems, Ltd

Patients with suspected acute aortic syndromes (AAS) often undergo CT with negative results. We sought clinical and diagnostic criteria that could be useful to identify low risk patients in order to reduce CT radiation exposure.  

We retrospectively identified all adults who presented to our emergency department (ED) and underwent a CT angiography for a suspected AAS based on clinical indication noted in the radiology report from 1/1/2006 - 8/1/2010, without history of trauma or AAS. Positive cases were defined as the presence of aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer and ruptured aneurysm. 1488 (60 yrs, 42% male) patients met inclusion criteria and formed the overall population. A detailed chart review using a case-control design was performed, with 4 controls for each case of AAS. 

2.6% (39/1488) of CTs were positive for AAS. An additional 6 cases, not identified in the ED, were diagnosed by CT after admission, a miss rate of 13% (6/45). The 39 AAS diagnosed in the ED (66 yrs, 44% Male) were significantly older than the 172 controls (59 yrs, 40% Male) (p=0.01). Risk factors associated with AAS included abnormal chest x-ray [OR=16.8, p<0.001; Sens 78.1% (25/32), Spec 82.5% (113/137)] and acute onset chest pain [OR =14.0, p<0.001; Sens 85.3% (29/34), Spec 70.7% (111/157)], which, when both absent, had a 3.7% (1/27) probability of AAS. All patients with AAS had continuous pain upon presentation to ED, a sensitivity of 100%. Additionally, AAS was refuted in all 19 subjects with non-continuous pain upon ED presentation. Hypertension was present in a large majority of both cases (81.6%) and controls (74.4%) (p=0.35).

97.4% of CT angiograms for suspected AAS scans in the ED were negative, yet 13% of AAS were missed in the ED and diagnosed after admission. Patients whose chest pain resolved on ED presentation and those with neither abnormal chest x-ray nor acute onset of chest pain were very unlikely to have AAS. Pretest probability criteria for patients with suspected AAS needs to be refined in order to diagnose patients expeditiously and reduce radiation exposure.

Although of AAS is notoriously difficult, radiation exposure from negative CT scans cannot be ignored. We provide initial data for developing a targeted approach to CT utilization.

Lovy, A, Bellin, E, Esses, D, Levsky, J, Haramati, L, Pretest Probability and Appropriately Targeting CT Utilization for Suspected Aortic Dissection.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034369.html