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The septic versus nonseptic inflamed joint: MRI characteristics
M Graif1, M E Schweitzer, D Deely
1Tel Aviv Ichilov-Sourasky Medical Center, Sackler School of Medicine, Tel Aviv University, Israel.
Objective:
To differentiate the MR features of septic versus nonseptic inflamed joints.
Design And Patients:
Thirty patients were referred for MRI with inflamed joints (19 were subsequently found to be septic and 11 nonseptic). At 1.5 T enhanced MRI five groups of signs related to joint space, synovium, cartilage, bone and peri-articular soft tissue respectively were assessed and compared between the septic and nonseptic groups.
Results:
The prevalence of MRI findings in septic versus nonseptic joints (respectively) was as follows: effusion (79% vs 82%), fluid outpouching (79% vs 73%), fluid heterogeneity (21% vs 27%), synovial thickening (68% vs 55%), synovial periedema (63% vs 55%), synovial enhancement (94% vs 88%), cartilage loss (53% vs 30%), bone erosions (79% vs 38%), bone erosions enhancement (77% vs 43%), bone marrow edema (74% vs 38%), bone marrow enhancement (67% vs 50%), soft tissue edema (63% vs 78%), soft tissue enhancement (67% vs 71%), periosteal edema (11% vs. 10%). The presence of bone erosions appeared to be an indicator for an infected joint (P=0.072); coexistence of bone marrow edema slightly improves the significance (0.068). A similar trend was obtained when combining bone erosions with either synovial thickening, synovial periedema, bone marrow enhancement or soft tissue edema (P=0.075).
Conclusions:
The combination of bone erosions with marrow edema is highly suggestive for a septic articulation; the additional coexistence of synovial thickening, synovial edema, soft tissue edema or bone marrow enhancement increases the above level of confidence. Similar to conventional radiography, the single sign that appeared to show a significant trend was the presence of bone erosions. However, no single sign or combination could either be considered pathognomonic or exclude the presence of a joint infection.
Insights
Magnetic resonance imaging (MRI) findings can help differentiate septic from nonseptic inflamed joints. Bone erosions combined with bone marrow edema are highly suggestive of joint infection, aiding diagnosis.
Area of Science:
- Radiology
- Orthopedics
- Infectious Diseases
Background:
- Inflamed joints require accurate differentiation between septic and nonseptic causes.
- Magnetic resonance imaging (MRI) offers detailed visualization of joint structures.
Purpose of the Study:
- To identify and compare MRI features distinguishing septic from nonseptic inflamed joints.
- To assess the diagnostic value of specific MRI findings in joint infections.
Main Methods:
- Thirty patients with inflamed joints underwent 1.5 T enhanced MRI.
- MRI signs in joint space, synovium, cartilage, bone, and soft tissues were assessed.
- Findings were compared between septic (n=19) and nonseptic (n=11) groups.
Main Results:
- Bone erosions (79% vs 38%) and bone marrow edema (74% vs 38%) were more prevalent in septic joints.
- The combination of bone erosions with marrow edema showed a trend towards indicating infection (P=0.068).
- Certain combinations of findings increased confidence in diagnosing septic arthritis.
Conclusions:
- Bone erosions and marrow edema are significant indicators of septic arthritis.
- No single MRI sign or combination is pathognomonic or can exclude joint infection.
- MRI findings aid in differentiating septic from nonseptic joint inflammation.