Using Diffusion Weighted Imaging and Blood Inflammatory markers to preoperatively differentiate between leiomyosarcoma and atypical leiomyomas.

Objectives: This study aims to compare apparent diffusion coefficient (ADC) findings between leiomyosarcoma (LMS) and atypical/degenerate leiomyoma (LM) and evaluate the usefulness of this biomarker for diagnosis. Additionally it will explore the potential of preoperative neutrophil lymphocyte ratio (NLR) as a haematological marker to aid in the differentiation of LMS from atypical LM.

Methods: Histologically proven LMS and LM patients between 2013-2023 were included. For all patients (191 LM, 18 LMS), the pre-operative full blood count was analysed, and the NLR calculated. Whole volume of interest (VOI) and focal region of interest (ROI) areas were manually segmented on patients with DW-MRI sequences available (52 LM, 12 LMS). Mann-Whitney and Fishers exact test were used to assess statistical significance and ROC curves for diagnostic performance.

Results: VOI and ROI mean ADC values were significantly lower for LMS than LM, with ROI mean ADC demonstrating greater diagnostic accuracy (AUC 0.817 vs 0.755). Applying a threshold ROI mean ADC value of ≤ 1.00 x10-3 mm2/sec achieved a sensitivity and specificity of 88.3% and 65.4% respectively. A higher NLR was suggestive of LMS (median 2.8 vs 1.7 for LM).

Conclusions: ADC, particularly a focal ROI is useful in differentiating LMS from LM. Differences in preoperative blood markers, suggest an inflammatory-malignancy relationship. Future risk stratification models of ADC and haematological parameters should be explored.

Advances in knowledge: This study adds to few studies comparing using both ROI and VOI based methods, and no study has assessed both haematological markers and ADC metrics to aid differentiation.