Small-sized soft tissue tumor with deep location: Can MRI be used to differentiate benign from malignancy?
Ji Hyun Lee1, Hyun Su Kim1, Young Cheol Yoon1, Wook Jin2, and Jang Gyu Cha3

1Radiology, Samsung Medical Center, SEOUL, Korea, Republic of, 2Radiology, Kyung Hee University Hospital at Gangdong, Seoul, Korea, Republic of, 3Radiology, Soonchunhyang University Bucheon Hospital, Bucheon, Korea, Republic of


Small deep soft tissue tumors often results in dilemmatic clinical situation and raise clinical concern that deep location is one of risk factor for malignancy. We conducted this study hypothesizing that DWI with ADC value as well as conventional MRI parameters could help differentiation of benignity and malignancy for small deep soft tissue tumors; univariable and multivariable analyses were performed for all tumors and non-myxoid non-hemosiderin tumors. Although only small tumors were enrolled, lesion size was still important for differentiation of benign and malignant soft tissue tumors, being the most significant parameter in non-myxoid non-hemosiderin group.


Small soft tissue tumors (STT) often results in dilemmatic clinical situation owing to substantially overlapping MRI features of benign and malignant lesions or presence of malignant STTs despite of small size and benign-looking MRI findings. When the STT is deeply located, they are often not palpable and may be challenging to be sampled especially when they are small or in close proximity to neurovascular bundles. In addition, non-diagnostic or false-negative biopsy further complicate the differential diagnosis of malignant versus benign STTs. Recently, several studies were reported suggesting that diffusion-weighted imaging (DWI) may improve diagnostic performance in differentiating benign from malignant STTs. Also, there have been investigations suggesting that apparent diffusion coefficient (ADC) values could be influenced by myxoid or hemosiderin component of STTs. Under the hypothesis that DWI with ADC value could help differentiation of benign and malignancy, we conducted this study to investigate the ability of DWI and conventional MRI parameters to differentate between benign and malignant small-sized deeply located STTs for all STS and non-myxoid non-hemosiderin STTs.


Between May 2011 and December 2017, 95 MRIs in 95 patients with pathologically proven STTs of small-size (<5cm) and deep location (66 benign and 29 malignant tumors) were identified. For DWI parameter, two radiologists independently analyzed the mean ADC values. For conventional MRI parameters, consensus reading was performed by three radiologists for following parameters: presence of necrosis, infiltration, lobulation, and tail sign. Maximum diameter of the lesion based on three orthogonal dimensions were also measured. Univariable and multivariable analyses for the diagnostic performances of conventional MRI parameters and ADCs in differentiating benign and malignant were performed in all STTs and in non-myxoid non-hemosiderin STTs using the logistic regression.


For all STTs group, the malignant group showed significantly larger maximum diameter, lower mean ADC, and higher incidence of all conventional MRI parameters than those of benign STTs with univarable analysis. Maximum size (P=0.008; OR, 3.004), mean ADC (p=0.028; OR, 0.205), and tail sign (p=0.006; OR, 8.415) were independently significant. For non-myxoid non-hemosiderin STTs group, age (p=0.037), maximum size (p=0.006), mean ADC (p=0.003), the presence of infiltration (p=0.004), necrosis (p=0.049), and tail sign (p=0.045) showed significant differences between malignancy and benignity with univariable analysis. Maximum size (p=0.019; OR, 5.509) and mean ADC (p=0.032; OR, 0.003) were independently significant among these parameters.


Despite the fact that ADC was independently significant for all STTs and non-myxoid non-hemosiderin STTs and only STTs less than 5 cm were enrolled, size was still more important parameter for differentiation of benign and malignant STTs. Malignant STTs showed higher incidence of tail sign; with multivariable analysis, statistical significance was found only in all STTs group.


ADC values as well as conventional MRI parameters were useful for differentiation of small-sized deeply-located benign and malignant STTs. The maximum size was the most significant MRI parameter in non-myxoid non-hemosiderin STTs.




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Proc. Intl. Soc. Mag. Reson. Med. 27 (2019)