Muscle shear wave elastography, conventional B mode and power doppler ultrasonography in healthy adults and patients with autoimmune inflammatory myopathies: a pilot cross-sectional study

Abstract

Background Before the role of shear wave elastography (SWE) and B mode ultrasound (US) in the diagnosis of different forms of idiopathic inflammatory myopathies (IIM) can be investigated, normative data is required. This study aimed to describe and then compare normative SWE and B mode ultrasound metrics of muscles in healthy controls and patients with IIM. Methods Twenty nine healthy adult controls and 10 IIM patients (5 with inclusion body myositis and 5 with necrotising autoimmune myopathy) underwent a full clinical examination, laboratory investigations, SWE and US measurements of selected proximal and distal limb muscles. Shear wave speed (SWS) and multiple US domains [echogenicity, fascial thickness, muscle bulk and power Doppler (PD)] were measured in both groups. Results In healthy controls (n = 29; mean age 46.60 ± 16.10; 44.8 % female), age was inversely correlated with SWS at the deltoid (stretch) (Rs. -0.40, p = 0.030) and PD score at the deltoid (rest) (Rs. -0.40, P = 0.032). Those ≥ 50 years old had a lower SWS at the deltoid (stretch) compared to the < 50 year group (2.92 m/s vs. 2.40 m/s, P = 0.032). Age correlated with increased echogenicity in the flexor digitorum profundus (Rs. 0.38, P = 0.045). Females had a smaller muscle bulk in the deltoid (P = 0.022). Body mass index (BMI) was inversely associated with SWS in the deltoid (stretch) (Rs – 0.45, P = 0.026), and positively correlated with echogenicity in the deltoid (Rs. 0.69, P = 0.026). In patients ≥50 years of age, patients with IIM (mean age 61.00 ± 8.18; females 20.0 %) had a higher proportion of abnormal echogenicity scores at the flexor digitorum profundus (FDP) (40.00 % vs. 14.30 %, P = 0.022) and tibialis anterior (TA) (80.00 % vs. 28.60 %, P = 0.004). Fascial thickness was lower in the FDP (0.63mm vs. 0.50mm, p = 0.012) and TA (0.58mm vs. 0.45mm, P = 0.001). Conclusions Our findings suggest there is scope for US techniques to be useful for diagnostic screening of affected muscles in patients with IIM, especially in those with suspected inclusion body myositis or necrotising autoimmune myopathy. We provide normative data for future studies into SWE and US techniques in skeletal muscle. The differences between IIM patients and controls warrant further study in a broader IIM patient cohort.

Muscle Sonography in Inclusion Body Myositis: A Systematic Review and Meta-Analysis of 944 Measurements

“…A total of 7 studies [ 25 , 36 , 37 , 38 , 39 , 40 , 41 ], with 108 IBM patients and 171 healthy controls, were included in the analysis. Four studies [ 25 , 36 , 38 , 41 ] reported the echogenicity of the flexor digitorum profundus (FDP) and gastrocnemius (GC) muscle groups with 168 participants (76 IBM patients and 92 controls).…”

“…Four studies [ 25 , 36 , 38 , 41 ] reported the echogenicity of the flexor digitorum profundus (FDP) and gastrocnemius (GC) muscle groups with 168 participants (76 IBM patients and 92 controls). Two studies [ 38 , 39 ] reported the muscle thickness of the FDP with 128 participants (46 IBM patients and 82 controls). Three studies [ 36 , 37 , 40 ] were involved in diagnostic test accuracy meta-analysis.…”

“…Paramalingam et al compared a group of five IBM patients to a group of age- and sex-matched healthy controls. The results showed no significant association between the muscle thickness of the FDP in IBM patients and in the control [ 39 ].…”

“…The threshold analysis for different cut-off values was made using Spearmann’s Test in an attempt to identify the reason for heterogeneity, and yielded no effect. Only three [ 36 , 37 , 39 ] out of the seven studies [ 25 , 36 , 37 , 38 , 39 , 40 , 41 ] evaluated the inter-rater or intra-rater reliability of the measurements. Accordingly, publication bias assessment could not be performed due to the small number of included studies.…”

Limitations of Muscle Ultrasound Shear Wave Elastography for Clinical Routine—Positioning and Muscle Selection

“…In group-level comparisons, muscle elasticity as determined by ultrasound SWE has been found to be altered in different myopathies [7,8,10], e.g., elasticity is likely reduced in idiopathic inflammatory myopathies (IIM) when compared to healthy controls [24,25]. Such features may serve as diagnostic indicators.…”