Volume fractions of DCE-MRI parameter as early predictor of histologic response in soft tissue sarcoma: A feasibility study.

OBJECTIVE

To find early predictors of histologic response in soft tissue sarcoma through volume transfer constant (K) analysis based on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

MATERIALS AND METHODS

11 Patients with soft tissue sarcoma of the lower extremity that underwent preoperative chemoradiotherapy followed by limb salvage surgery were included in this retrospective study. For each patient, DCE-MRI data sets were collected before and two weeks after therapy initiation, and histologic tumor cell necrosis rate (TCNR) was reported at surgery. The DCE-MRI volumes were aligned by registration. Then, the aligned volumes were used to obtain the K variation map. Accordingly, three sub-volumes (with increased, decreased or unchanged K) were defined and identified, and fractions of the sub-volumes, denoted as F, F and F, respectively, were calculated. The predictive ability of volume fractions was determined by using area under a receiver operating characteristic curve (AUC). Linear regression analysis was performed to investigate the relationship between TCNR and volume fractions. In addition, the K values of the sub-volumes were compared.

RESULTS

The AUC for F (0.896) and F (0.833) were larger than that for change of tumor longest diameter ΔD (0.625) and the change of mean KΔK¯ (0.792). Moreover, the regression results indicated that TCNR was directly proportional to F (R=0.75, P=0.0003), while it was inversely proportional to F (R=0.77, P=0.0002). However, TCNR had relatively weak linear relationship with ΔK¯ (R=0.64, P=0.0018). Additionally, TCNR did not have linear relationship with DD (R=0.16, P=0.1246).

CONCLUSION

The volume fraction F and F have potential as early predictors of soft tissue sarcoma histologic response.