The incidence and diagnostic relevance of chemical shift artefact in the magnetic resonance imaging characterisation of superficial soft tissue masses.

Chemical shift artefact (CSA) is often encountered during MRI evaluation of superficial soft tissue masses. The study aim was to determine the incidence and diagnostic relevance of CSA in a consecutive series of superficial soft tissue masses referred to a specialist musculoskeletal sarcoma service. All patients referred over a 6 month period with a non-lipomatous superficial soft tissue mass were prospectively analysed. Patients characteristics (age, gender), lesion features (anatomical location, size, relationship to the skin and deep fascia), presence of CSA and final histopathological diagnosis were collected. The presence of CSA was statistically analysed against these clinical, imaging and histopathological variables. 128 patients fulfilled the inclusion criteria [63 males, 65 females; mean age = 50.6 years (7-96 years)]. CSA was present in 50 cases (39.1%) overall, but in 39 (41.5%) of 94 cases with histological diagnosis. There was no statistically significant relationship to any assessed variable apart from relationship to the deep fascia, CSA being more frequent in lesions contacting the fascia compared to lesions contacting both skin and fascia ( The presence of CSA is a not infrequent finding in the MRI assessment of superficial soft tissue masses but does not appear to be of any significance in differentiating between non-malignant and malignant lesions. CSA is a relatively common finding in association with superficial soft tissue masses, but does not indicate a particular histological diagnosis or help in the differentiation of non-malignant from malignant lesions.