Melanie Chang MD, Presenter: Nothing to Disclose

Michael Thomas Corwin MD, Abstract Co-Author: Nothing to Disclose

Ghaneh Fananapazir MD, Abstract Co-Author: Nothing to Disclose

J. Anthony Seibert PhD, Abstract Co-Author: Nothing to Disclose

Ramit Lamba MD, Abstract Co-Author: Nothing to Disclose

To determine the accuracy and radiation dose reduction of a limited abdominopelvic CT from the bottom of the T10 vertebral body to the top of the pubic symphysis in patients with suspected acute appendicitis.

This was a retrospective review of patients greater than 18 years of age who underwent CT abdomen and pelvis for suspected acute appendicitis. Scout line mode was used to correlate axial images with the CT localizer radiographs to define the limited range CT from the bottom of the T10 vertebral body to the top of the pubic symphysis. The original scan was prescribed from the lung bases to the ischial tuberosities. The Z-axis lengths of the full and theoretical limited scans were recorded. Radiation dose estimates were made using a commercial software package that estimates effective dose using an anthropomorphic phantom and Monte Carlo methods. All images were reviewed to determine if the appendix or entire cecum (in cases where the appendix was not visualized) would be visualized with the limited scan. The images were reviewed to determine if any cases of appendicitis or alternative diagnoses would be missed with the limited scan.

235 patients (89 male, mean age 44.6 years) were included. The limited scan resulted in a mean Z-axis length reduction of 5.1 cm superiorly, 6.1 cm inferiorly, and a total reduction of 111.7 cm (24.1%). The mean whole body effective dose was 11.8 mSv and 9.1 mSv for the original and limited scans respectively (21.2% reduction). In females, the mean breast equivalent dose was 6.4 mSv and 0.9 mSv for the full and limited scans respectively (85.4% reduction). The entire appendix or cecum was visualized in all cases. Appendicitis was present in 24 cases and an alternative diagnosis was made in 75 cases with urolithiasis the most common alternative finding (n = 22). No cases of appendicitis or alternative diagnoses would have been missed using the limited scan.

A limited range CT from the bottom of T10 to the top of the pubic symphysis is as accurate as full abdominopelvic CT in evaluating patients with suspected acute appendicitis and results in approximately 20% dose reduction.

A limited range CT is an effective technique to reduce radiation dose in patients undergoing MDCT for suspected acute appendicitis.

Chang, M, Corwin, M, Fananapazir, G, Seibert, J, Lamba, R, Accuracy and Radiation Dose Reduction of a Limited Abdominopelvic CT in the Diagnosis of Acute Appendicitis..  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009388.html