Orthopedic surgeons have long found inlet and outlet views (I/O) of the pelvis to be helpful in their management of pelvic fractures. However, for the last decade we’ve seen an inexorable creep in diagnostic imaging from plain xrays to computed techniques. Have the conventional inlet and outlet views lost their luster?
San Francisco General Hospital and UCSF recently published a registry-based study looking at conventional pelvic I/O images and virtual I/O images reconstructed from CT scans. Two years of registry data were reviewed, and included patients had both conventional I/O images and CT imaging. Images were evaluated by two orthopedic traumatologists for their quality.
Sadly, only 20 patients were available for this study, which makes it an interesting pilot at best. The most interesting results were as follows:
- Quality of imaging was judged to be equal except when pelvic rotation was present. CT fared better in these cases.
- Both inlet and outlet views were judged to be better when reconstructed by CT
- Overall, imaging of all portions of the pelvis was about equal in both types of study
- The need for repeat studies was identified in nearly half of conventional images, but in only 8% of CT images
Bottom line: CT scanning is slowly becoming the preferred modality for just about any type of trauma imaging. In the 1980’s, head CTs became widespread, followed rapidly by abdominal imaging. Chest CT for definitive diagnosis became commonplace around 2000, and spine imaging by CT has now become the gold standard. Although there are a few throwbacks where conventional imaging has been thought to be better, they are vanishing rapidly. Computing technology can now reconstruct inlet and outlet views of the pelvis, correcting for rotation and angulation in any study of the abdomen/pelvis. And if the reconstructed image is not quite right, the tech can change a few parameters and generate it again and again until the image is perfect.
Orthopedic surgeons should now expect a nicely formatted set of inlet/outlet CT reconstructions in all trauma patients with pelvic fractures.
Reference: Are conventional inlet and outlet radiographs obsolete in the evaluation of pelvis fractures? J Trauma 74(6):1510-1515, 2013.