Three-Dimensional Quantitative Assessment of Uterine Fibroid Response after Uterine Artery Embolization Using Contrast-Enhanced MR Imaging

Abstract

PurposeTo evaluate the clinical feasibility and diagnostic accuracy of three-dimensional (3D) quantitative magnetic resonance (MR) imaging for the assessment of total lesion volume (TLV) and enhancing lesion volume (ELV) before and after uterine artery embolization (UAE). Materials and MethodsThis retrospective study included 25 patients with uterine fibroids who underwent UAE and received contrast-enhanced MR imaging before and after the procedure. TLV was calculated using a semiautomated 3D segmentation of the dominant lesion on contrast-enhanced MR imaging, and ELV was defined as voxels within TLV where the enhancement exceeded the value of a region of interest placed in hypoenhancing soft tissue (left psoas muscle). ELV was expressed in relative (% of TLV) and absolute (in cm3) metrics. Results were compared with manual measurements and correlated with symptomatic outcome using a linear regression model. ResultsAlthough 3D quantitative measurements of TLV demonstrated a strong correlation with the manual technique (R2 = 0.93), measurements of ELV after UAE showed significant disagreement between techniques (R2 = 0.72; residual standard error, 15.8). Six patients (24%) remained symptomatic and were classified as nonresponders. When stratified according to response, no difference in % ELV between responders and nonresponders was observed. When assessed using cm3 ELV, responders showed a significantly lower mean ELV compared with nonresponders (4.1 cm3 [range, 0.3–19.8 cm3] vs 77 cm3 [range, 11.91–296 cm3]; P < .01). ConclusionsThe use of segmentation-based 3D quantification of lesion enhancement is feasible and diagnostically accurate and could be considered as an MR imaging response marker for clinical outcome after UAE.