Evaluating Hip Periprosthetic Joint Infection with Metal-artifact-reduction MR Imaging

Abstract

Purpose: To evaluate the significant findings of hip periprosthetic joint infection (PJI) using metal-artifact-reduction (MAR) MRI and to compare the MRI results to other clinical markers.

Methods: The results of MRI, including two-dimensional fast-spin echo sequences with increased bandwidth and multi-acquisition variable-resonance image combination selective for hips with orthopedic implants at 1.5T (from April 2014 to November 2021), were retrospectively assessed for imaging findings and diagnostic impressions by two radiologists. Clinical data and courses were also investigated. Univariate and multivariate analyses were performed to identify the significant MRI findings in patients with hip PJI and those who underwent surgical intervention. The MRI impressions were compared with other clinical markers in diagnosing hip PJI.

Results: Thirty-seven hip joints in 24 Asian patients (age = 73.9 ± 10.8 years; 18 females) were included. Twelve hip joints (32%) had PJI; seven underwent a surgical intervention. The significant findings for hip PJI included periosteal edema of the acetabulum, intermuscular edema, intramuscular fluid collection, and lymphadenopathy (P < 0.05). In the cases with surgical intervention, the significant findings included capsular distension, capsular thickening, an osteolysis-like pattern of the femur, subcutaneous fluid collection, and lymphadenopathy (P < 0.05). The MRI impressions had high diagnostic significance for both hip PJI cases and those with surgical intervention (P < 0.001). The MRI impression was more significant for hip PJI than the other clinical markers (P < 0.05), while the other clinical markers were more significant in the cases with surgical intervention (P < 0.05).

Conclusion: The significant findings in the hip PJI cases included acetabular periosteal edema, intermuscular edema, intramuscular fluid collection, and lymphadenopathy. The significant findings in the cases with surgical intervention included capsular distention, capsular thickening, a femoral osteolysis-like pattern, subcutaneous fluid collection, and lymphadenopathy. The utilization of MAR MRI demonstrated great diagnostic significance for hip PJI.

Keywords: MRI; hip; metal-artifact-reduction; multi-acquisition variable-resonance image combination selective; periprosthetic joint infection.

Fig. 1

An 86-year-old female at 1 year and 8 months after total hip arthroplasty in the right hip had pain on motion and slightly increased D-dimers, but no increase in serum white blood cell count, C-reactive protein, or erythrocyte sedimentation rate. The absence of periprosthetic infection was confirmed through clinical signs and course. The MRI impressions of the two readers based on a 6-grade scale were 4 and 2. (a) A coronal T2-weighted image by 2D-FSE with increased bandwidth. (b) A coronal proton-density-weighted image by MAVRIC-SL. (c) A coronal STIR image by MAVRIC-SL. (a) A large and severe signal defect and image distortion are observed at the right hip joint (arrows). (b and c) The signal defect and image distortion at the right hip joint are reduced. MAVRIC-SL improves the visualization of the bone–implant interface and surrounding soft tissue compared to 2D-FSE. A well-delineated signal change is noted at the right acetabular roof around the cup on STIR by MAVRIC-SL, which shows high signal intensity on STIR (curved arrows). These findings suggest an osteolysis-like pattern of the acetabulum.

Fig. 2

A 77-year-old female at 10 years and 11 months after total hip arthroplasty in the left hip had fever, pain, and swelling around the left hip, along with increased C-reactive protein, white blood cell count, and erythrocyte sedimentation rate. A late infection of the left hip arthroplasty was diagnosed. The MRI impressions of two readers based on a 6-grade scale were 6 and 6. (a) A coronal STIR image by 2D-FSE with increased bandwidth. (b and c) Coronal STIR images by MAVRIC-SL. (d) A transverse STIR image by 2D-FSE with increased bandwidth. (a) A signal defect with severe image distortion at the left hip joint is noted. Intramuscular fluid collection is observed medial to the left hip joint, but the presence of communication with the hip joint is unclear. (b) Intramuscular fluid collection located medially to the left hip joint, with communication to the left hip joint, is again observed (thin arrow). Periosteal edema is observed in the left acetabulum and ileum (curved arrows). A mild bone marrow edema pattern is also observed in the left acetabulum and ileum. (c) Intramuscular and intermuscular edema and fluid collection are observed around the left hip joint (gluteal muscles and pectineus muscle) (arrows). Periosteal edema is also noted at the medial aspect of the proximal femur (thin arrow). (d) Periosteal edema and fluid signals are observed around the proximal site of the left femur (arrows). Fluid signals are also observed around the stem within the left femur, exhibiting an osteolysis-like pattern (thin arrows), which communicates to the fluid signals and edema around the left femur. In the left inguinal region, two enlarged lymph nodes are identified (arrowheads).

Fig. 3

A 79-year-old female at 18 years and 3 months after bipolar hip arthroplasty in the left hip presented with pain and elevated C-reactive protein and erythrocyte sedimentation rate. A late periprosthetic infection in the left hip joint was diagnosed based on clinical signs and course. The impressions of the two readers based on a 6-grade scale were 5 and 5. (a) A transverse T2-weighted image by 2D-FSE with increased bandwidth. (b) A coronal STIR image by MAVRIC-SL. (c) A sagittal STIR image by MAVRIC-SL. (a) An oval-shaped signal defect is observed at the left hip joint. In addition, an enlarged lymph node is detected in the left external iliac region (arrowhead). (b) A moderate amount of joint effusion with capsular distension and mild capsular thickening are observed in the left hip joint (arrows). A mild bone marrow edema pattern is noted around the femoral stem (curved arrows). (c) Joint effusion and periarticular edema are noted (arrowhead).

Fig. 4

An 88-year-old female at 10 years and 11 months after bipolar hip arthroplasty presented with swelling and erythema around the right hip joint, along with a mildly increased erythrocyte sedimentation rate. A late infection of the right hip arthroplasty was diagnosed. The MRI impressions of the two readers based on a 6-grade scale were 6 and 6. (a) A transverse T2-weighted image by 2D-FSE with increased bandwidth. (b and c) Coronal STIR images by MAVRIC-SL. (a) An oval-shaped signal defect is observed in the right hip joint. An encapsulated, lobulated fluid collection is noted in the subcutaneous fat surrounding the greater trochanter of the right femur (arrows). Two enlarged lymph nodes are observed in the right inguinal region (arrowheads). (b and c) A moderate amount of joint effusion with capsular distension and thickening are observed in the right hip joint (arrowheads). An encapsulated, lobulated fluid collection is noted in the subcutaneous area around the greater trochanter of the right femur, which communicates with the right hip joint (arrows). Periosteal edema of the acetabulum is present (curved arrows). An enlarged lymph node is noted in the right obturator lymph node area (thin arrow).