MRgFUS Uterine Fibroids treatments in Sicily: Preliminary Results and comparison of a Semi-Automatic and manual contouring

Abstract

Background: Traditional surgery for uterine fibroids treatments (e.g. myomectomy, hysterectomy) offers very invasive therapeutic approaches, which not always preserve reproductive potential of the woman. MRgFUS (MR guided Focused UltraSound) is a new and non-invasive technique for uterine fibroids treatment, not requiring hospitalization and recovery time [1]. On June 2011 and July 2012 the first treatments were started at HSR-Giglio Hospital in Cefalù and at University Hospital (DIBIMEF) in Palermo. An initial assessment of MRgFUS treatment was made by computing the thermally-ablated volume of uterine fibroid. This volume was evaluated considering the NPV (Non Perfused Volume) on a post-treatment MR dataset acquired with contrast medium. Nowadays, the used approach is a time-expensive and operator-dependent manual segmentation procedure. In this paper, the preliminary results of the two Sicilian facilities are showed and a semi- automatic segmentation approach is proposed, based on multi-seed region-growing technique, to calculate the NPV. The realized approach gives a quantitative evaluation in the post-treatment phase. Materials and Methods: The MRgFUS procedures, regarding women affected by single/multiple uterine fibroid, were performed using the ExAblate 2000 and 2100 (InSightec, Haifa, Israel), which is fully integrated with a 1.5 Tesla MR Scanner (GE Medical System, Milwaukee, WI). For NPV manual and semi-automatic evaluation we have used the sagittal or coronal images acquired after the treatment with a gadolinium-based contrast medium (FSPGR+FS+C protocol). The proposed semi-automatic approach in based on multi-seed region-growing, where it is possible to individualize the processing steps: • pre-processing filtering; • region-growing segmentation; • post-processing filtering; • NPV computation. Results: Among all 23 performed treatments, 69.57% have obtained a NPV, manually evaluated, bigger than 60%, successful treatment threshold, and the 65.22% > 70% and 47.83% > 80%. The evaluation of our segmentation approach was performed by calculating Jaccard and Dice similarity indexes and specificity and sensitivity values. In order to obtain the above indexes, the results of the proposed region-growing approach were compared with the manual segmentation. Preliminary segmentation tests obtained the following results: • Jaccard Index: 87.83%; • Dice Index: 94.12%; • Sensitivity: 91.59%; • Specificity: 89.72%. Conclusion: The MRgFUS provides an important new non-invasive and effective treatment for uterine fibroids. The proposed multi-seed region-growing segmentation approach allows to estimate the NPV in a semi-automatic and operator-independent way. Obtained segmentation indexes show the effectiveness of the implemented technique.