German researchers have advanced the cause of CT-based diagnosis of appendicitis, touting the accuracy and sensitivity of the imaging modality in a routine setting and in a comparison with ultrasound.
Dr. Dick Pickuth from Martin Luther University in Halle presented two studies at the European Congress of Radiology conference in March. Spiral CT was used to evaluate acute appendicitis, and was then compared to ultrasonography in clinical performance.
"The emphasis is really on the routine setting here," Pickuth said. "Many diseases are incorrectly diagnosed as appendicitis. With clinical evaluation alone, appendicitis is ignored in every fifth patient."
In the first study, appendiceal CT was performed in 120 consecutive patients with suspected acute appendicitis, whose clinical findings were insufficient to perform surgery or discharge them. Each scan was obtained in a single breath-hold from the lower abdomen to the upper pelvis using 5 mm collimation and a pitch of 1.6. CT results were correlated with surgical and pathologic findings at appendectomy.
Of the 93 patients with acute appendicitis, CT correctly diagnosed 88, Pickuth reported. Out of the 27 patients who did not have acute appendicitis, CT ruled out the disease in 24 cases. The sensitivity for CT was 95% and the specificity was 85%, with a negative predictive value of 83%. The CT signs for acute appendicitis included fat stranding in 100% of the patients, enlargement in 93%, and adenopathy in 63%.
CT also was able to lead investigators to other problems, such as ureteral stones, gynecological disorders, and Crohn's disease, Pickuth said.
"There was quite a range of different diseases, and CT definitely helped with the further management of these patients," he said.
In the second prospective study, and using the same patient population, spiral CT was compared to ultrasound. CT results had a sensitivity of 95%, a specificity of 89%, a positive predictive value of 97%, and a negative predictive value of 83%.
By comparison, ultrasound had a sensitivity of 86%, a specificity of 77%, a positive predictive value of 93%, and a negative predictive value of 61%.
"The use of spiral CT led to a significant improvement in the preoperative diagnosis and a lower negative appendectomy rate," the authors concluded.
Other advantages that CT offers include the ability to image obese patients or those with perforated appendixes, Pickuth said. However, CT does require that the reader have a solid knowledge of the right lower abdominal quadrant and an awareness of the other diseases that can mimic appendicitis, he added.
The researchers did not address any cost implications of choosing CT or ultrasound.
Previous studies have recommended CT for obese patients, as well as older ones with diagnostic dilemmas. At the 1996 Radiological Society of North America meeting, Dr. Patrick Rao of Massachusetts General Hospital promoted CT-based appendix exams with a study that found a 98% accuracy rate. A follow-up study, published in Radiology in 1997, backed up those initial findings, demonstrating that CT had a sensitivity of 100%, a specificity of 95%, and overall accuracy of 98% (Radiology, Jan. 1997, Vol. 202:1, pp.139-144).
Still, ultrasound is considered the primary diagnostic modality for suspected appendicitis and has achieved similar diagnostic efficacy. Clinicians at the Huntington Memorial Hospital in Pasadena, CA, performed a prospective study of patients evaluated in the emergency department for acute appendicitis with Doppler ultrasound. According to the results, 10 of the 12 patients with abnormal Doppler activity had appendicitis. Ultrasound had a sensitivity of 90%, and a specificity of 94% (Am Surg, Nov. 1999, Vol.65:11, pp.1015-1017).
By Shalmali Pal
AuntMinnie.com staff writer
April 12, 2000
Let AuntMinnie.com know what you think about this story.
Copyright © 2000 AuntMinnie.com
