Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?

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.

"Water-lily sign" as a rare finding of spinal hydatidosis.

Hydatid disease (HD) is a common parasitic infestation in some developing countries. Hydatid disease may affect many organs in the body, but the most affected are the liver and lungs. Hepatic and pulmonary HD is relatively easier to diagnose because of the frequency of pathognomic features and its order in the differential diagnosis list. When HD is located in uncommon sites, it is difficult to recognize even in endemic areas. The "water-lily sign" is a pathognomic sign for HD and mostly described especially after puncture or percutaneous treatment of the cyst. In this case, we observed the water-lily sign in spinal HD, which was not described before for spinal cases but for soft tissues.

Optimizing MR signal contrast of the temporomandibular joint disk.

PURPOSE: To use a tissue specific algorithm to numerically optimize UTE sequence parameters to maximize contrast within temporomandibular joint (TMJ) donor tissue. MATERIALS AND METHODS: A TMJ specimen tissue block was sectioned in a true sagittal plane and imaged at 3 Tesla (T) using UTE pulse sequences with dual echo subtraction. The MR tissue properties (PD, T(2) , T(2) *, and T(1) ) were measured and subsequently used to calculate the optimum sequences parameters (repetition time [TR], echo time [TE], and θ). RESULTS: It was found that the main contrast available in the TMJ could be obtained from T(2) (or T(2) *) contrast. With the first echo time fixed at 8 µs and using TR = 200 ms, the optimum parameters were found to be: θ ≈ 60°, and TE2 ≈ 15 ms, when the second echo is acquired using a gradient echo and θ ≈ 120°, and TE2 ≈ 15 ms, when the second echo is acquired using a spin echo. CONCLUSION: Our results show that MR signal contrast can be optimized between tissues in a systematic manner. The MR contrast within the TMJ was successfully optimized with facile delineation between disc and soft tissues.

Magnetic resonance imaging of the temporomandibular joint disc: feasibility of novel quantitative magnetic resonance evaluation using histologic and biomechanical reference standards.

AIMS: To use the ultrashort time-to-echo magnetic resonance imaging (UTE MRI) technique to quantify short T2* properties (obtained through gradient echo) of a disc from the human temporomandibular joint (TMJ) and to corroborate regional T2* values with biomechanical properties and histologic appearance of the discal tissues. METHODS: A cadaveric human TMJ was sliced sagittally and imaged by conventional and UTE MRI techniques. The slices were then subjected to either biomechanical indentation testing or histologic evaluation, and linear regression was used for comparison to T2* maps obtained from UTE MRI data. Feasibility of in vivo UTE MRI was assessed in two human volunteers. RESULTS: The UTE MRI technique of the specimens provided images of the TMJ disc with greater signal-to-noise ratio (~3 fold) and contrast against surrounding tissues than conventional techniques. Higher T2* values correlated with lower indentation stiffness (softer) and less collagen organization as indicated by polarized light microscopy. T2* values were also obtained from the volunteers. CONCLUSION: UTE MRI facilitates quantitative characterization of TMJ discs, which may reflect structural and functional properties related to TMJ dysfunction.

Pediatric abdominal masses: diagnostic accuracy of diffusion weighted MRI.

PURPOSE: To retrospectively identify apparent diffusion coefficient (ADC) values of pediatric abdominal mass lesions, to determine whether measured ADC of the lesions and signal intensity on diffusion-weighted (DW) images allow discrimination between benign and malignant mass lesions. MATERIALS AND METHODS: Approval for this retrospective study was obtained from the institutional review board. Children with abdominal mass lesions, who were examined by DW magnetic resonance imaging (MRI) were included in this study. DW MR images were obtained in the axial plane by using a non breath-hold single-shot spin-echo sequence on a 1.5-T MR scanner. ADCs were calculated for each lesion. ADC values were compared with Mann-Whitney U test. Receiver operating characteristic curve analysis was performed to determine cut-off values for ADC. The results of visual assessment on b800 images and ADC map images were compared with chi-square test. RESULTS: Thirty-one abdominal mass lesions (16 benign, 15 malignant) in 26 patients (15 girls, 11 boys, ranging from 2 days to 17 years with 6.9 years mean) underwent MRI. Benign lesions had significantly higher ADC values than malignant ones (P < .001). The mean ADCs of malignant lesions were 0.84 +/- 1.7x10(-3) mm2/s, while the mean ADCs of the benign ones were 2.28 +/- 1.00x10(-3) mm2/s. With respect to cutoff values of ADC: 1.11x10(-3) mm2/s, sensitivity and negative predictive values were 100%, specificity was 78.6% and positive predictive value was 83.3%. For b800 and ADC map images, there were statistically significant differences on visual assessment. All malignant lesions had variable degrees of high signal intensity whereas eight of the 16 benign ones had low signal intensities on b800 images (P < .001). On ADC map images, all malignant lesions were hypointense and most of the benign ones (n=11, 68.7%) were hyperintense (P < .001). CONCLUSION: DW imaging can be used for reliable discrimination of benign and malignant pediatric abdominal mass lesions based on considerable differences in the ADC values and signal intensity changes.