Ultrasonography performed by an infectiologist in hip and knee prosthetic joint and native joint infections.

INTRODUCTION: Clinical ultrasonography (US) by infectiologists has only recently been developing, and as now there is little literature on the subject. Our study focuses on the conditions and diagnostic performance of clinical ultrasound imaging by infectiologists in cases of hip and knee prosthetic and native joint infection. METHODS: A retrospective study carried out between June 1st 2019 and March 31st 2021 in the University Hospital of Bordeaux, South-Western France. We measured US sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV), combined or not with the analysis of articular fluid, compared to the MusculoSketetal Infection Society (MSIS) score in prosthetic joints, or to expert diagnosis in native joints. RESULTS: Fifty-four patients underwent US by an infectiologist in an infectious disease ward, including 11 (20.4%) for native joint and 43 (79.6%) for prosthetic joint. Joint effusion and/or periarticular collection were highlighted in 47 (87%) patients, and US led to 44 punctures. In all patients (n = 54), Se, Sp, PPV and NPV of US alone were 91%, 19%, 64% and 57%, respectively. When US was combined with fluid analysis, Se, Sp, PPV, NPV were 68%, 100%, 100%, 64% in all patients (n = 54), 86%, 100%, 100%, 60% in acute arthritis (n = 17) and 50%, 100%, 100% and 65% respectively in non-acute arthritis (n = 37). CONCLUSION: These results suggest that US by infectiologists effectively diagnoses osteoarticular infections (OAIs). This approach has many applications in infectiology routines. Consequently, it would be interesting to define the contents of a first level of infectiologist competence in US clinical practice.

Evaluation of hepatic iron concentration heterogeneities using the MRI R2* mapping method.

OBJECTIVE: To measure hepatic iron concentration (HIC) heterogeneities using a magnetic resonance R2* mapping method. PATIENTS AND METHODS: Ninety-four patients with suspected hepatic iron overload and 10 volunteers were included prospectively. A multi-echo R2* sequence with fat saturation and with three post-processing fitting methods (a single exponential decay model with or without truncation, SED and SEDt, and a constant offset model, COS) was compared to a signal intensity ratio method (SIR), considered as the reference. HIC heterogeneity was evaluated from R2* mapping after placing a ROI on each liver segment. RESULTS: A strong linear correlation between SIR and R2* methods using the SEDt and COS models was observed (r = 0.973 and 0.955, respectively). Volunteers and patient liver variabilities, quantified by mean intra-liver standard deviation (SD) were 1.58 µmol/g (mean range 5.06 µmol/g) and 4.73 µmol/g (mean range 19.08 µmol/g), respectively. For the patient group, the highest HIC was observed in the IVth segment. Heterogeneity increased for patients with an HIC > 60 µmol/g (mean intra-liver SD = 13.90 µmol/g; mean range = 50.60 µmol/g). CONCLUSION: This study is the first to demonstrate in vivo HIC heterogeneities using whole-liver mapping analysis. These preliminary results require confirmation through further studies, but might be useful in cases of single ROI analysis.