EVALUATION OF FACTORS AFFECTING THE LONG-TERM RESULTS OF MAGNETIC RESONANCE IMAGING GUIDED FOCUSED ULTRASOUND ABLATION OF UTERINE FIBROIDS

Abstract

Objective: to analyze the results of focused ultrasound ablation (MRgFUS) of uterine fibroids and to evaluate the factors affecting the long-term results of treatment. Material and methods. Retrospective analysis of 67 FUS ablations (67 women, 94 fibroids) was performed. The observation period after FUS was up to 36 months. Characteristics of fibroids (standardized signal intensity (SSI) and signal heterogeneity in T2-WI, maximum diameter, volume, nonperfused volume (NPV), coefficients of volume and NPV dynamics (CDV, CDNPV), MR-type) were assessed by MRI. Standardization of the fibroid signal intensity was performed by using the signal intensity from iliac muscle. CDV, CDNPV were calculated as the ratio of fibroids volume and NPV at the time of control MRI to their initial values. Results. Post treatment NPV ratio was 57.1 ± 22.5%. The maximal significant reduction of fibroids volume and NPV was detected by 12 months after FUS (52.1% and 85.8%). CDV and CDNPV showed significant (p<0.05) correlation with post treatment NPV ratio (r=-0.5 and r=0.37), fibroids volume (r=0.28 and r=0.49) and maximum diameter (r=0.26 and r=0.49). Fibroids with NPV ≥50% and volume <150 cm3 were characterized by the highest rate of volume reduction. Fibroids with NPV≥75% and volume >100 cm3 were characterized by the lowest rate of NPV reduction. The maximal reduction of volume during the observation period was detected in fibroids with NPV≥75% and volume <100 cm3, the minimal – in fibroids with NPV<25% and volume >150 cm3. Conclusion. The dynamics of fibroids volume and NPV after MRgFUS depends on initial values of these characteristics.