In a recent study presented at the annual meeting of the Radiological Society of North America (RSNA) researchers showed how the DICOM viewer, OsiriX, can effectively help diagnose acute appendicitis.

This doesn’t come as much of a surprise to us.  We reviewed OsiriX a few months ago and were definitely fans of this DICOM viewer then.

My only issue is with the lack of information provided in the study.  You can view the abstract of the study but the full study is currently not yet published.  Yes, the findings are interesting, but lets hold back some of the excitement until we get more information.  I’ve seen multiple medical and non medical outlets reporting on this story, but I don’t think they are looking at how the study itself was performed in detail.  The main points mentioned in the abstract were the following:

25 Abdomen and Pelvis CT studies performed on patients with right lower quadrant pain were identified. All patients had either surgical confirmation of the diagnosis of acute appendicitis or followup clinical evaluation confirming no acute appendicitis. Each study was viewed by five blinded radiologists on a handheld device (iPhone) using a DICOM viewer (OsiriX). Studies were evaluated for the ability to find the appendix, the maximum appendiceal diameter, presence of an appendicolith, periappendicial stranding and fluid, abscess formation, and a binary assessment of the diagnosis of acute appendicitis. Studies were compared to a faculty-read of the study as performed on a dedicated PACS workstation.

-Choudhri, et. al (Link to Abstract)

15 cases of acute appendicitis were correctly identified on 74 of 75 interpretations (99%), with one false negative. No false positive readings were seen in this study. 8 appendicoliths were correctly identified on 35 of 40 interpretations (88%). 3 abscesses were correctly identified by all five readers. There was greater than 90% agreement on the presence of peri-appendiceal stranding and free fluid. The iPhone measurement of appendiceal diameter averaged 0.9 ± 0.7 mm larger than the value obtained on a PACS workstation (p=0.04).

-Choudhri, et. al (Link to Abstract)

These are just some of the few questions I have for this study and I’m hoping they will be addressed once the full study is published:

  1. How were the residents blinded?
  2. I’d like to know more about the selection criteria for the 25 CT studies included.  What was the researchers definition of “right lower quadrant” pain.  If the threshold for right lower quadrant pain was high, then making a diagnosis of acute appendicitis via imaging might be significantly easier due to a higher burden of disease.
  3. I’d also like to see the results when 25 random Abdomen and Pelvic CTs are included that do not meet the inclusion criteria of right lower quadrant pain. There might be some false positives that come out of this arm.

Hopefully some of these answers will be answered once the full study is published.