Imaging of the Pelvis

Imaging of the pelvis can present a significant challenge for the musculoskeletal radiologist. There is often considerable overlap of signs and symptoms as they relate to various sports-related injuries or other pathological processes that involve the osseous pelvis or the adjacent soft tissues structures. Depending on the expertise of the referring physician, the history provided at the time of imaging may offer little guidance as it pertains to tailoring of the imaging examination. Common histories often include such vague phrases as “pelvic pain,” “groin pain,” or “hip pain.”

Another complicating factor with regard to high-quality imaging is the large field of view required to visualize the entire pelvis. The soft tissue anatomy of the pelvis is quite complex and often poorly understood by the radiologist, and many of the anatomical structures are small and would be better assessed with a small field of view. Not too many years ago, imaging of the pelvis and hips resulted in more “negative” magnetic resonance (MR) examinations than just about any other joint in the body. That has begun to change over the past few years with an increased awareness and better understanding of several entities such as femoroacetabular impingement syndrome, athletic pubalgia, and the sports hernia, and it is becoming increasingly important to have a good working diagnosis prior to imaging, to ensure an appropriately tailored imaging study.

This issue of Seminars in Musculoskeletal Radiology deals primarily with the imaging of sports-related injuries that occur in and about the pelvis exclusive of the hips. Entities such as femoroacetabular impingement, labral tears, and other causes of internal derangement of the hip are discussed in a separate issue.

We begin with Zajick et al's excellent overview of the clinical syndrome of athletic pubalgia. An extensive differential diagnosis is offered along with an imaging strategy that will improve diagnostic accuracy when evaluating a patient with this clinical diagnosis. Next, the complex anatomy and various injury patterns of the iliopsoas (Blankenbaker and Tuite) and the hamstring musculotendinous units (Davis) are described in two separate articles. The next article, written by Sanders and Zlatkin, deals with the imaging appearance and diagnosis of avulsion injuries of the pelvis. Whereas avulsion injuries occur most often in the adolescent athlete following vigorous athletic activity or trauma, several lesser known avulsion injuries can also occur in the adult or in the postoperative setting, which are also discussed.

Next, Shortt et al review the entity commonly referred to as sportsman's hernia, based on their experience with imaging more than 350 patients with this clinical diagnosis. The article does a superb job of defining the pertinent and complex anatomy associated with the sports hernia and then nicely outlines the common MR findings associated with this entity. The musculoskeletal portion of this issue is rounded out with an article on stress injuries of the pelvis (Campbell and Fajardo) and imaging of the sacroiliac joints (Tuite).

Finally, the last article, which I consider a real treat, deals with a problem that I personally often find perplexing. Entitled “MRI of the Pelvis: A Guide to Incidental Findings for Musculoskeletal Radiologists,” Childs and Leyendecker have done a superb job of outlining the important considerations when evaluating the intraperitoneal structures of the pelvis that are often incidentally included within the field of view when performing imaging of the pelvis for musculoskeletal indications. The tables in the article provide a very useful summary of which findings are important and which are not and the appropriate follow-up imaging recommended for each. I can visualize these tables pasted to musculoskeletal reading stations all across the country to be used as a quick reference guide for incidental abnormalities discovered while imaging the pelvis.

I would like to thank the each of the authors who have contributed their time and expertise to make this issue a reality. It has been a real pleasure working with each of them. Finally, I hope you find each article in this issue as helpful as I did in updating your knowledge regarding the evolving role of imaging as it relates to musculoskeletal abnormalities of the pelvis.