Muscle B mode ultrasound and shear-wave elastography in idiopathic inflammatory myopathies (SWIM): criterion validation against MRI and muscle biopsy findings in an incident patient cohort

Abstract

Background B mode ultrasound (US) and shear wave elastography (SWE) are easily accessible imaging tools for idiopathic inflammatory myopathies (IIM) but require further validation against standard diagnostic procedures such as MRI and muscle biopsy. Methods In this prospective cross-sectional study we compared US findings to MRI and muscle biopsy findings in a group of 18 patients (11 F, 7 M) with active IIM (dermatomyositis 6, necrotising autoimmune myopathy 7, inclusion body myositis 4, overlap myositis 1) who had one or both procedures on the same muscle. US domains (echogenicity, fascial thickness, muscle bulk, shear wave speed and power doppler) in the deltoid and vastus lateralis were compared to MRI domains (muscle oedema, fatty infiltration/atrophy) and muscle biopsy findings (lymphocytic inflammation, myonecrosis, atrophy and fibro-fatty infiltration). A composite index score (1–4) was also used as an arbitrary indicator of overall muscle pathology in biopsies. Results Increased echogenicity correlated with the presence of fatty infiltration/atrophy on MRI (p = 0.047) in the vastus lateralis, and showed a non-significant association with muscle inflammation, myonecrosis, fibrosis and fatty infiltration/atrophy (p > 0.333) Severe echogenicity also had a non-significant association with higher composite biopsy index score in the vastus lateralis (p = 0.380). SWS and US measures of fascial thickness and muscle bulk showed poor discrimination in differentiating between pathologies on MRI or muscle biopsy. Power Doppler measures of vascularity correlated poorly with the presence of oedema on MRI, or with inflammation or fatty infiltration on biopsy. Overall, US was sensitive in detecting the presence of muscle pathology shown on MRI (67–100%) but showed poorer specificity (13–100%). Increased echogenicity showed good sensitivity when detecting muscle pathology (100%) but lacked specificity in differentiating muscle pathologies (0%). Most study participants rated US as the preferred imaging modality. Conclusions Our findings show that US, in particular muscle echogenicity, has a high sensitivity, but low specificity, for detecting muscle pathology in IIM. Traditional visual grading scores are not IIM-specific and require further modification and validation. Future studies should continue to focus on developing a feasible scoring system, which is reliable and allows translation to clinical practice.

Sonoelastography: A powerful technique in musculoskeletal imaging

“…Similar greater sensitivity of sonoelastography versus grayscale US for early stages of tendinopathy have been reported in the Achilles, quadriceps, biceps, supraspinatus, and other tendons 9,14–17 . Sonoelastography has also been applied to osteoarthritic cartilage, the transverse ligament in carpal tunnel syndrome, myopathies, ligaments, rheumatoid synovitis, methotrexate hepatotoxicity (important in rheumatology), meniscal disease, trigger finger, and musculoskeletal tumors with similar changes in elasticity of the relevant tissue with variable sensitivity and specificity for pathology versus alternative imaging methods 14–25 …”

“…The low cost, convenience, noninvasive nature, lack of ionizing radiation, direct relevance to palpable anatomy, point‐of‐care applicability, and increasing number of applications indicate that US will only increase in use in musculoskeletal medicine 1–4 . Sonoelastography is another powerful method available to observe the musculoskeletal system, and appears particularly valuable in detecting early tendinopathies, areas of myopathy suitable for biopsy, pursuing complaints of localized musculoskeletal pain, analyzing soft tissue masses, and research applications in musculoskeletal medicine 14–25 . Shear wave elastography in particular permits rapid quantitative assessments of musculoskeletal structures and will be particularly valuable at the beside, in research studies and clinical trials, and in monitoring disease presence, progression, and response to therapy, especially in muscle and tendon disease.…”

“…9,[14][15][16][17] Sonoelastography has also been applied to osteoarthritic cartilage, the transverse ligament in carpal tunnel syndrome, myopathies, ligaments, rheumatoid synovitis, methotrexate hepatotoxicity (important in rheumatology), meniscal disease, trigger finger, and musculoskeletal tumors with similar changes in elasticity of the relevant tissue with variable sensitivity and specificity for pathology versus alternative imaging methods. [14][15][16][17][18][19][20][21][22][23][24][25] US is increasingly becoming an extension of the physical examination in musculoskeletal medicine. 1 The low cost, convenience, noninvasive nature, lack of ionizing radiation, direct relevance to palpable anatomy, point-of-care applicability, and increasing number of applications indicate that US will only increase in use in musculoskeletal medicine.…”

“…[1][2][3][4] Sonoelastography is another powerful method available to observe the musculoskeletal system, and appears particularly valuable in detecting early tendinopathies, areas of myopathy suitable for biopsy, pursuing complaints of localized musculoskeletal pain, analyzing soft tissue masses, and research applications in musculoskeletal medicine. [14][15][16][17][18][19][20][21][22][23][24][25] Shear wave elastography in particular permits rapid quantitative assessments of musculoskeletal structures and will be particularly valuable at the beside, in research studies and clinical trials, and in monitoring disease presence, progression, and response to therapy, especially in muscle and tendon disease. It is anticipated that sonoelastography will increase in specificity, sensitivity, depth of imaging, and applications as the technology of this US method becomes increasingly sophisticated.…”

Correction to: Muscle B mode ultrasound and shear-wave elastography in idiopathic inflammatory myopathies (SWIM): criterion validation against MRI and muscle biopsy findings in an incident patient cohort

“…Following publication of the original article [ 1 ], it was reported that there was an error in the caption for Fig. 1A .…”