Authors (including presenting author) :
Chau HTH(1), Ng OW(1), Pan NY(1)
Affiliation :
(1)Radiology Department, Princess Margaret Hospital
Introduction :
Palpable soft tissue masses are common and are often referred for imaging evaluation. Literature does not support the use of Magnetic Resonance Imaging (MRI) as the initial examination for superficial or palpable soft-tissue mass. Hong Kong College of Radiologists (HKCR) Radiology Clinical Referral Guidelines (2019) and American College of Radiology (ACR) Appropriateness Criteria ® Soft-Tissue Masses recommended ultrasonography (US) as initial imaging study for superficial or palpable soft-tissue masses. US has the advantages of having high-spatial-resolution and allowing real time imaging in low cost. Most importantly, it does not rely on ionizing radiation. In most of the cases, US can accurately characterize the lesion, obviate biopsy and reduce unnecessary further work-up. As a result, it can reduce the overall cost and shorten the MRI appointment time.
Objectives :
Utilizing US to diagnose palpable superficial soft tissue masses in daily practice and reducing unnecessary MRI for palpable superficial soft-tissue masses. The target is that all palpable superficial soft-tissue masses (100%) should be evaluated by US prior MRI examination.
Methodology :
MRI performed for palpable superficial soft-tissue masses in the period of Aug 2022 to Jan 2023 in Princess Margaret Hospital were identified on the Radiology Information System (RIS) and cases were reviewed. Previously diagnosed masses or masses initially identified from other imaging modalities are excluded. Excel was used for data analysis. Parameters being analyzed included: referring department, body region, diagnosis, size of mass, and if the mass was initially imaged with US.
Result & Outcome :
There were 66 cases collected in total while 89.4% of the referrals were from orthopaedics department. Small proportion of referral from surgical, medical and pediatric departments. Majority of the cases (87.8%) involved the upper and lower limbs. Only 36.4% of palpable superficial soft tissue masses were evaluated by US prior MRI examination. No superficial soft-tissue mass was demonstrated on MRI in almost a fourth of cases (24.2%), which could have been excluded if US was performed. About a fourth of the cases (25.8%) were subcutaneous lipoma, which could be confidently diagnosed on US. Cases including ganglion cyst / bursa (6.1%), nerve sheath tumor (10.6%), slow flow vascular tumor (10.6%) could also be identified on US. Majority of the masses were less than 5cm in size (72%). Four cases were subcentimeter lesions which were better seen on USG which allowed better spatial resolution. Based on our data, majority of the MRI superficial soft tissue mass cases could have been diagnosed with US. Therefore, palpable superficial mass should be initially triaged and evaluated by US as recommended by HKCR and ACR. Results and recommendations were delivered to clinicians (including orthopedic, surgical, medical and pediatric) in clinical meetings or by email. Radiology specialists who are responsible for vetting the MRI form were reminded to send memo to referrers to recommend US before MRI study. Plan to re-audit for improvement after a year.
