New Applications of Sonoelastography in Rheumatology

Where Are We Now?

Teresa Martins-Rocha; Irene Azzolin; Teodora Serban; Giuseppe Massazza; Annamaria Iagnocco

Disclosures

Rheumatology. 2019;58(5):765-769. 

In This Article

Abstract and Introduction

Abstract

Ultrasound elastography (UE) is a non-invasive imaging method that allows the assessment of tissue elastic property. Different UE techniques are currently available (i.e. strain UE and acoustic radiation force impulse UE), with several potential clinical applications. Recent studies investigated the role of UE in two systemic rheumatic diseases and psoriasis. This research added interesting information to the already known applications of UE in the assessment of tendinopathies. In SS, acoustic radiation force impulse UE has shown a potential role in the diagnosis of the disease, with lower sensitivity than and similar specificity to salivary gland histology. In SSc, a potential use of UE in screening pre-clinical disease has been reported. In psoriasis, the use of strain UE in evaluating treatment response has been highlighted. UE is a promising tool in rheumatology, with a potential role in the evaluation of various tissues and pathologies.

Introduction

Ultrasound elastography (UE) is a non-invasive technique that measures tissue stiffness in response to mechanical stress. Two types of UE are currently available, namely strain elastography and shear wave elastography.[1,2] In the former, repetitive continuous manual pressure is applied by the transducer to the tissues. A qualitative colour-coded or grey-scale map of the elastic module distribution is displayed (elastogram) and a semi-quantitative evaluation can be drawn. Operator dependency and difficult qualitative/semi-quantitative evaluation are disadvantages associated with this technique.[2–4] On the other hand, in shear wave elastography, a focal acoustic radiation force impulse (ARFI) is applied to generate local tissue displacements, and the velocity of the shear waves can be quantified to evaluate the stiffness of the tissues. The stiffer a tissue is, the faster the propagation of the shear waves will be, and therefore the higher the shear wave velocity (SWV).[3,5] In contrast to strain UE, ARFI allows quantitative measurements of tissue stiffness. Two quantitative ARFI modes have been described: virtual touch tissue quantification (VTQ), which enables calculation of SWV, and virtual touch tissue imaging quantification (VTIQ), which also displays an elastogram.[6] Finally, virtual tissue imaging (VTI) is another ARFI qualitative technique in which an elastogram is displayed; however, it cannot be used to calculate SWV.[4]

During recent years, UE application has been recommended in several clinical fields, namely in the assessment of liver fibrosis, breast and prostate cancer screening, thyroid lesions, and lymph nodes evaluation.[4,7–9] In addition to this, UE has also been used in numerous musculoskeletal diseases, such as chronic Achilles tendinopathy, muscle spasticity, rotator cuff tendinopathy, and carpal tunnel syndrome.[10–16] Particularly, in Achilles tendinopathy, strain UE was found to depict soft regions corresponding to areas of mucoid degeneration and partial ruptures,[10] and ARFI UE detected slower SWV values compared with controls.[11]

Furthermore, recent interesting studies focused on the potential application of UE in some systemic rheumatic and skin diseases. In this narrative review, we aimed to report the new evidence concerning UE applications in SS, SSc and psoriasis.

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