Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023—overview, and primary local imaging: how and where?
Authors: Noebauer-Huhmann Iris-Melanie , Vanhoenacker Filip M. , Vilanova Joan C. , Tagliafico Alberto S. , Weber Marc-André , Lalam Radhesh K. , Grieser Thomas , Nikodinovska Violeta Vasilevska , de Rooy Jacky W. J. , Papakonstantinou Olympia , Mccarthy Catherine , Sconfienza Luca Maria , Verstraete Koenraad , Martel-Villagrán José , Szomolanyi Pavol , Lecouvet Frédéric E. , Afonso Diana , Albtoush Omar M. , Aringhieri Giacomo , Arkun Remide , Aström Gunnar , Bazzocchi Alberto , Botchu Rajesh , Breitenseher Martin , Chaudhary Snehansh , Dalili Danoob , Davies Mark , de Jonge Milko C. , Mete Berna D. , Fritz Jan , Gielen Jan L. M. A. , Hide Geoff , Isaac Amanda , Ivanoski Slavcho , Mansour Ramy M. , Muntaner-Gimbernat Lorenzo , Navas Ana , O´Donnell Paul , Örgüç Şebnem , Rennie Winston , Resano Santiago , Robinson Philip , Sanal Hatice T. , Ter Horst Simone A. J. , van Langevelde Kirsten , Wörtler Klaus , Koelz Marita , Panotopoulos Joannis , Windhager Reinhard , Bloem Johannes L. 
Published: December 2023

Abstract
Objectives
Early, accurate diagnosis is crucial for the prognosis of patients with soft tissue sarcomas. To this end, standardization of imaging algorithms, technical requirements, and reporting is therefore a prerequisite. Since the first European Society of Musculoskeletal Radiology (ESSR) consensus in 2015, technical achievements, further insights into specific entities, and the revised WHO-classification (2020) and AJCC staging system (2017) made an update necessary. The guidelines are intended to support radiologists in their decision-making and contribute to interdisciplinary tumor board discussions.

Materials and methods
A validated Delphi method based on peer-reviewed literature was used to derive consensus among a panel of 46 specialized musculoskeletal radiologists from 12 European countries. Statements were scored online by level of agreement (0 to 10) during two iterative rounds. Either “group consensus,” “group agreement,” or “lack of agreement” was achieved.

Results
Eight sections were defined that finally contained 145 statements with comments. Overall, group consensus was reached in 95.9%, and group agreement in 4.1%. This communication contains the first part consisting of the imaging algorithm for suspected soft tissue tumors, methods for local imaging, and the role of tumor centers.

Conclusion
Ultrasound represents the initial triage imaging modality for accessible and small tumors. MRI is the modality of choice for the characterization and local staging of most soft tissue tumors. CT is indicated in special situations. In suspicious or likely malignant tumors, a specialist tumor center should be contacted for referral or teleradiologic second opinion. This should be done before performing a biopsy, without exception.

Clinical relevance
The updated ESSR soft tissue tumor imaging guidelines aim to provide best practice expert consensus for standardized imaging, to support radiologists in their decision-making, and to improve examination comparability both in individual patients and in future studies on individualized strategies.

Key Points
• Ultrasound remains the best initial triage imaging modality for accessible and small suspected soft tissue tumors.
• MRI is the modality of choice for the characterization and local staging of soft tissue tumors in most cases; CT is indicated in special situations. Suspicious or likely malignant tumors should undergo biopsy.
• In patients with large, indeterminate or suspicious tumors, a tumor reference center should be contacted for referral or teleradiologic second opinion; this must be done before a biopsy.