Shamir Rai BSC, Presenter: Nothing to Disclose

Triona M. Walshe FFR(RCSI), Abstract Co-Author: Nothing to Disclose

Chesnal Dey Arepalli MD, Abstract Co-Author: Nothing to Disclose

Brathaban Rajayogeswaran MBBCh, Abstract Co-Author: Nothing to Disclose

Patrick McLaughlin FFR(RCSI), Abstract Co-Author: Nothing to Disclose

Tim O'Connell MD, Meng, Abstract Co-Author: President, Resolve Radiologic Ltd

Savvas Nicolaou MD, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to evaluate whether non-contrast enhanced abdominal CT scans obtained through virtual non-contrast (VNC) CT scans, were equally sensitive and specific in diagnosing acute appendicitis as contrast-enhanced abdominal CT studies.

A total of 23 consecutive patients who underwent a dual energy (DE) CT for suspected appendicitis were identified retrospectively, between the dates of Dec 28, 2013 to March 2, 2014 at a single institution’s emergency department. Of these cases, 13 were surgically and pathologically confirmed to be appendicitis, the other 10 cases were determined to be clinically negative for appendicitis. VNC CT studies were constructed from the contrast-enhanced DE abdominal CT scans for all cases. Two radiologists, one an abdominal radiologist, the other a MSK radiologist, were blinded and retrospectively interpreted the VNC CT images, assessing for pathology and diagnostic confidence. Readers were asked to record whether the appendix was seen, the size of the appendix and whether they suspected the patient had appendicitis and their confidence level (on a scale of 1-10, with 1 representing no confidence and 10 representing high confidence) on evaluation of both the VNC CT and contrast-enhanced CT.

The abdominal radiologist (AR) was not able to identify the appendix in only 1 VNC case. No cases of appendicitis were missed, however. The AR had a calculated 100% accuracy for the diagnosis for appendicitis. The median confidence scores between VNC and contrast enhanced CT’s were equal (9 and 9 respectively; p=0.026). MSK radiologist (MSKR) was unable to identify the appendix in 9 cases and subsequently missed 4 cases of appendicitis. MSKR median confidence scores were significantly decreased for the VNC study versus the contrast enhanced study (9 and 10 respectively; p=0.027). The calculated sensitivity was 66% (0.34-0.9) and specificity of 100% (0.54-1.00) for the MSK radiologist.

Non-contrast enhanced CT has the potential to be diagnostic with a high accuracy in the hands of experienced abdominal radiologists. However, contrast enhanced abdominal CT studies still have a role in diagnosing acute appendicitis in not so experienced radiologists.

Contrast enhanced CT abdominal studies facilitate relatively easy diagnosis of acute appendicitis in not so experienced radiologists.

Rai, S, Walshe, T, Arepalli, C, Rajayogeswaran, B, McLaughlin, P, O'Connell, T, Nicolaou, S, Diagnosis of Acute Appendicitis on CT - Is there a Role for Contrast Enhanced Abdominal CT Studies?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019528.html