Location of bone marrow edema helps diagnose this kind of arthritis

A thorough assessment of bone marrow edema (BME) and its precise anatomic location on MRI scans may be helpful in distinguishing patients with axial spondyloarthritis (axSpA) from those with other conditions, according to results presented at the 2018 American College of Rheumatology (ACR)/the Association of Rheumatology Health Professionals (ARHP) Annual Meeting.

Specifically, Danish researchers found that BME adjacent to joint space, erosion, and fat occurs most frequently, but not exclusively, in patients with axSpA.

“We have very effective medical treatments for axSpA that reduce disease activity, and improve the signs and symptoms of the disease. However, it’s clinically difficult to differentiate patients with axSpA from patients with buttock pain for other reasons,” said study co-author Sengül Heidi Seven, MD, PhD student, Copenhagen Center for Arthritis Research, Copenhagen, Denmark. “MRI is frequently used for axSpA diagnosis because it can visualize BME, but these may also occur in other diseases, as well as in very active athletes, such as long-distance runners. There is a need for a better way to establish diagnosis early in the disease course, through more detailed assessment of MRIs of sacroiliac joints.”

Dr. Seven and colleagues, therefore, conducted the prospective, cross-sectional MASH study to assess the possible advantages of specifically determining—and noting—the location of MRI-detected BME and other MRI lesions in the sacroiliac joint to distinguish patients with axSpA from those with other conditions.

In all, 204 patients were included: 41 with axSpA, 25 with lumbar disc herniation, 26 engaged in hard physical labor, 23 long-distance runners (30 km or more per week), 29 healthy men, 46 women with pain related to pregnancy or postpartum within 12 months after delivery, and 14 women without postpartum pain.

Those with pain were required to have a Visual Analog Scale (VAS) pain score of > 2 for 2 or more months. All patients without axSpA could not have clinical features of SpA or any rheumatologic conditions.

Subjects all underwent clinical and laboratory exams, as well as MRI examination that included semi-coronal short tau inversion recovery and T1-weighted sequences of the sacroiliac joints. All MRIs were assessed by two independent readers for BME, erosion, fat, ankylosis, and sclerosis. The left and right sacroiliac joints were also examined separately for BME.

Dr. Seven and fellow researchers more frequently found BME adjacent to joint space, erosions, and fat in patients with axSpA, although this was also seen in other subgroups, particularly in women with postpartum pain. BME adjacent to sclerosis was most common in women with postpartum pain (28%). Finally, BME adjacent to ankylosis was only observed in patients with axSpA (2%).

The higher cut-offs were reached almost exclusively by patients with axSpA. For example, a full 63% of patients with axSpA had one or more BMEs adjacent to joint space compared with 44% of those with postpartum pain, 21% with no postpartum pain, 8% in both disc herniation and hard physical labor, 0% of long distance runners, and 3% of healthy men. Five or more BMEs adjacent to joint space occurred most commonly—again—in patients with axSpA (46%) compared with 9%, 7%, and 0% in each of the four remaining groups, respectively. The same was true for 10 or more BMEs, which occurred in 17% of patients with axSpA, compared with 2% in patients with postpartum pain, and 0% in each of the five remaining groups.

“Improved diagnosis of these patients will result in more patients getting the most appropriate diagnosis and treatment, potentially leading to optimized outcomes for both people with and without axSpA. Data from this study will potentially help rheumatologists diagnose axSpA patients more accurately in clinical practice, and this may also potentially improve selection of patients for clinical trials,” concluded Dr. Seven.