Background: 

The diagnosis of periprosthetic shoulder infection (PSI) in patients with a painful arthroplasty is challenging. Magnetic resonance imaging (MRI) may be helpful, but shoulder implant-induced metal artifacts degrade conventional MRI. Advanced metal artifact reduction (MARS) improves the visibility of periprosthetic bone and soft tissues. The purpose of our study was to determine the reliability, repeatability, and diagnostic performance of advanced MARS-MRI findings for diagnosing PSI.

Methods: 

Between January 2015 and December 2019, we enrolled consecutive patients suspected of having PSI at our academic hospital. All 89 participants had at least 1-year clinical follow-up and underwent standardized clinical, radiographic, and laboratory evaluations and advanced MARS-MRI. Two fellowship-trained musculoskeletal radiologists retrospectively evaluated the advanced MARS-MRI studies for findings associated with PSI in a blinded and independent fashion. Both readers repeated their evaluations after a 2-month interval. Interreader reliability and intrareader repeatability were assessed with κ coefficients. The diagnostic performance of advanced MARS-MRI for PSI was quantified using sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC). When applying the International Consensus Meeting (ICM) 2018 criteria, of the 89 participants, 22 (25%) were deemed as being infected and 67 (75%) were classified as being not infected (unlikely to have PSA and not requiring a surgical procedure during 1-year follow-up).

Results: 

The interreader reliability and intrareader repeatability of advanced MARS-MRI findings, including lymphadenopathy, joint effusion, synovitis, extra-articular fluid collection, a sinus tract, rotator cuff muscle edema, and periprosthetic bone resorption, were good (κ = 0.61 to 0.80) to excellent (κ > 0.80). Lymphadenopathy, complex joint effusion, and edematous synovitis had sensitivities of >85%, specificities of >90%, odds ratios of >3.6, and AUC values of >0.90 for diagnosing PSI. The presence of all 3 findings together yielded a PSI probability of >99%, per logistic regression analysis.

Conclusions: 

Our study shows the clinical utility of advanced MARS-MRI for diagnosing PSI when using the ICM 2018 criteria as the reference standard. Although the reliability and diagnostic accuracy were high, these conclusions are based on our specific advanced MARS-MRI protocol interpreted by experienced musculoskeletal radiologists. Investigations with larger sample sizes are needed to confirm these results.

Level of Evidence: 

Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

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先进金属伪影减少 MRI 对假体周围感染的诊断性能

背景： 

对疼痛性关节成形术患者的假体肩部感染 (PSI) 进行诊断具有挑战性。磁共振成像 (MRI) 可能有帮助，但肩部植入物引起的金属伪影会降低传统 MRI。先进的金属伪影减少 (MARS) 提高了假体周围骨和软组织的可见度。我们研究的目的是确定用于诊断 PSI 的先进 MARS-MRI 结果的可靠性、可重复性和诊断性能。

方法： 

在 2015 年 1 月至 2019 年 12 月期间，我们在我们的学术医院连续招募了疑似患有 PSI 的患者。所有 89 名参与者都进行了至少 1 年的临床随访，并接受了标准化的临床、影像学和实验室评估以及先进的 MARS-MRI。两位接受过研究金培训的肌肉骨骼放射科医师以盲法和独立的方式回顾性地评估了先进的 MARS-MRI 研究中与 PSI 相关的发现。两位读者在 2 个月的间隔后重复他们的评估。使用 κ 系数评估读者间可靠性和读者内可重复性。使用灵敏度、特异性和受试者工作特征曲线下面积 (AUC) 来量化高级 MARS-MRI 对 PSI 的诊断性能。在应用 2018 年国际共识会议 (ICM) 标准时，

结果： 

高级 MARS-MRI 发现的读者间可靠性和读者内可重复性，包括淋巴结病、关节积液、滑膜炎、关节外积液、窦道、肩袖肌肉水肿和假体周围骨吸收，均良好 (κ = 0.61 至 0.80)至极好（κ > 0.80）。淋巴结病、复杂关节积液和水肿性滑膜炎对诊断 PSI 的敏感性 >85%，特异性 >90%，优势比 >3.6，AUC 值 >0.90。根据逻辑回归分析，所有 3 个结果的存在共同产生了 > 99% 的 PSI 概率。

结论： 

我们的研究表明，当使用 ICM 2018 标准作为参考标准时，先进的 MARS-MRI 用于诊断 PSI 的临床实用性。尽管可靠性和诊断准确性很高，但这些结论是基于我们由经验丰富的肌肉骨骼放射科医生解释的特定高级 MARS-MRI 协议。需要更大样本量的调查来确认这些结果。

证据等级： 

诊断级别 III。有关证据级别的完整描述，请参见作者说明。