Multiparametric Assessment of Treatment Response in High-Grade Soft-Tissue Sarcomas with Anatomic and Functional MR Imaging Sequences

Abstract

).q RSNA, 2015 Purpose:To determine the added value of quantitative diffusionweighted and dynamic contrast material-enhanced imaging to conventional magnetic resonance (MR) imaging for assessment of the response of soft-tissue sarcomas to neoadjuvant therapy. Materials and Methods:MR imaging examinations in 23 patients with soft-tissue sarcomas who had undergone neoadjuvant therapy were reviewed by two readers during three sessions: conventional imaging (T1-weighted, fluid-sensitive, static postcontrast T1-weighted), conventional with diffusion-weighted imaging, and conventional with diffusion-weighted and dynamic contrast-enhanced imaging. For each session, readers recorded imaging features and determined treatment response. Interobserver agreement was assessed and receiver operating characteristic analysis was performed to evaluate the accuracy of each session for determining response by using results of the histologic analysis as the reference standard. Good response was defined as less than or equal to 5% residual viable tumor. Results:Of the 23 sarcomas, four (17.4%) showed good histologic response (three of four with .95% granulation tissue and ,5% necrosis, one of four with 95% necrosis and ,5% viable tumor) and 19 (82.6%) showed poor response (viable tumor range, 10%-100%). Interobserver agreement was substantial or excellent for imaging features in all sequences (k = 0.789-1.000). Receiver operating characteristic analysis showed an increase in diagnostic performance with the addition of diffusion-weighted and dynamic contrast-enhanced MR imaging for prediction of response compared with that for conventional imaging alone (areas under the curve, 0.500, 0.676, 0. Conclusion:Adding functional sequences to the conventional MR imaging protocol increases the sensitivity of MR imaging for determining treatment response in soft-tissue sarcomas.q RSNA, 2015

Review of dynamic contrast‐enhanced MRI: Technical aspects and applications in the musculoskeletal system

“…DCE‐MRI increases diagnostic confidence for characterizing malignant lesions and serves as a baseline for posttreatment follow‐up. It helps assess for treatment response and the degree of viable residual malignant tumor, following neo‐adjuvant chemotherapy or radiation, and before surgery, in both bone and soft tissue malignancies …”

“…The addition of DCE‐MRI helps rectify this problem. Fibrosis and granulation tissue enhance slowly over time in comparison to rapidly enhancing residual tumor; in high grade soft tissue sarcomas, DCE‐MRI was shown to improve the accuracy of MRI for determining treatment response in patients in whom the tumor responded by the formation of scarring and granulation tissue rather than necrosis . Figure is an example of a sarcoma following neoadjuvant treatment, for which DCE‐MRI differentiated viable tumor from posttreatment enhancing granulation tissue and fibrosis.…”

“…Also, the detection volume of 3–5 mm 3 was considered as the lower threshold volume for detection of abnormal enhancement . Other authors have used a temporal resolution of greater than 6 s with success in differentiating benign and malignant entities …”

Evaluation of Soft Tissue Sarcoma Response to Preoperative Chemoradiotherapy Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging

“…The reports on soft tissue sarcoma staging and preoperative therapeutic monitoring using DCE-MRI are limited in the literature. In most studies, either qualitative description of the curve shape (9–12) or semiquantitative metrics, such as wash-in and wash-out rates (13, 14) or area-under-the-cure (13), were used in the analysis of DCE-MRI signal intensity time-course data. Although these 2 methods are simple and straightforward without the need for sophisticated mathematical modeling, the results are directly related to MRI signal change—not tissue biology, and are generally dependent on data acquisition protocol details and scanner platforms and settings, making it difficult to compare studies across institutions (15–17).…”

DCE-MRI, DW-MRI, and MRS in Cancer

“…In high-grade soft-tissue sarcomas, qualitative assessment of both DCE-MRI and DW-MRI performed better than standard morphological imaging for predicting response to NAC as verified at subsequent surgery, although the functional images were not assessed in combination. 132 A meta-analysis of 43 rectal cancer studies, 30 of which included DW-MRI and 13 DCE-MRI, indicated that both these techniques showed additional value in the prediction and detection of complete response to therapy compared with conventional T 2 -w sequences alone. 133 An ongoing multicenter trial in Australia is focusing on the prospective evaluation of quantitative mpMRI (ADC, K trans , k ep ) to stratify patients and guide radiation dosing.…”