Clinical, Technical, and MRI Features Associated with Patients' Outcome at 3 Months and 2 Years following Prostate Artery Embolization: Is There an Added Value of Radiomics?

Abstract

Our aim was to investigate which features were associated with clinical successes at short- and mid-terms following prostate artery embolization (PAE) for symptomatic benign prostate hypertrophy (BPH). All adults treated by PAE for BPH at our referral center between January 2017 and March 2021, with pre-treatment MRI, technical success, and follow-up at 3 months and 2 years were included in this single-center retrospective study. Radiologists reviewed the prostatic protrusion index (PPI), adenomatous dominant BPH (adBPH), and Wasserman classification on pre-treatment MRI. Radiomics analysis was achieved on the transitional zone on pre-treatment T2-weighted imaging (WI) and ADC, and comprised reproducibility assessment, unsupervised classifications, and supervised radiomics scores obtained with cross-validated Elasticnet regressions. Eighty-eight patients were included (median age: 65 years), with 81.8% clinical successes at 3 months and 60.2% at 2 years. No feature was associated with success at 3 months, except the radiomics score trained on T2-WI and ADC (AUROC = 0.694). Regarding success at 2 years, no radiomics approaches provided significant performances; however, Wasserman type-1 and change in international prostate symptom score (IPSS) at 3 months ≤ -35% were associated with success in multivariable analysis (OR = 5.82, p = 0.0296, and OR = 9.04, p = 0.0002). Thus, while radiomics provided limited interest, Wasserman classification and early IPSS changes appeared predictive of mid-term outcomes.

Keywords: lower urinary tracts symptoms; magnetic resonance imaging; outcome study; prognosis; prostate; prostate artery embolization; radiomics.

Figure 6

Summary of the radiomics analyses. The upper horizontal panel illustrates the univariable analysis. Volcano plots for the associations between the radiomics features (RFs) with clinical success at 3 months (M3) (A), and with clinical success at 2 years (Y2) (B). In the volcano plot, points located above the horizontal dotted line correspond to significant RFs. Points on the left of the vertical dotted line (negative Estimate, i.e., odds ratio [= exp(Estimate)]) < 1) are adverse predictors, and those on the right (positive Estimate, i.e., odds ratio > 1). Red points correspond to T2-based RFs, and blue points to ADC-based RFs. The middle horizontal panel corresponds to the unsupervised analysis and illustrates the consensual hierarchical clustering obtained on T2-based RFs (C), ADC-based RFs (D), and both ADC- and T2-based RFs (E). The lower horizontal panel shows the supervised analysis: cross-validated ROC curves with a 95% confidence interval (CI) for the best model at M3 (AUROC = 0.694, 95%CI = 0.552–0.836) (F), and at Y2 (AUROC = 0.607, 95%CI = 0.468–0.746) (G).

Figure 1

Study flow-chart. Abbreviations: BPH: benign prostate hyperplasia, LUTS: lower urinary tract symptoms, PACS: picture archiving and communication system, PAE: prostate artery embolization.

Figure 2

Radiomics workflow performed on pre-treatment MRI. Abbreviations: ADC: apparent diffusion coefficient, VOI: volume of interest, WI: weighted imaging.

Figure 3

Statistical pipeline. Clinical, radiological, and radiomics were all obtained before prostate artery embolization (PAE). Technical features were obtained during PAE. Abbreviations: ADC: apparent diffusion coefficient, AUROC: area under the ROC curve, ICC: intra-class correlation coefficient, PCA: principal component analysis, M3: at 3 months after prostate artery embolization, RF: radiomics feature, Y2: at 2 years after prostate artery embolization.

Figure 4

Patients’ outcomes following prostate artery embolization (PAE) for benign prostate hypertrophy. (A) Relative change in prostate volume between the pre-PAE MRI and the revaluation MRI at 3 months (M3) post-PAE. (B) Absolute changes in IPSS at M3 and the latest evaluation (after at least two years [Y2] of follow-up). (C) Absolute changes in QOL at M3 and the latest evaluation. (A–C) are boxplots with median, 1st, and 3rd quartiles with all patients being represented with points. (D) Proportion of patients with clinical success at M3 and Y2. (E) Kaplan-Meier.

Figure 5

ROC curve analysis for the relative change in IPSS. The point corresponding to the Youden index (i.e., maximizing sensitivity + specificity −1) is indicated with a black arrow. Abbreviations: AUROC: area under the ROC curve, CI: confidence interval.

Figure 7

Clinical examples. (A) A 54-year-old male underwent a bilateral prostate artery embolization (PAE) with glue and microparticles for lower urinary tract symptoms (LUTS) due to benign prostate hypertrophy (BPH) with initial IPSS = 19 and initial QOL = 5. The prostate was classified as Wasserman type 2 (black arrow). The relative change in IPSS at 3 months was +21.9% (>−35%). The patient declared no relief from his symptoms at 3 months and 2 years following PAE. (B) A 64-year-old male underwent a bilateral PAE with microparticles for LUTS due to BPH with initial IPSS = 25 and initial QOL = 5, and a Wasserman type 1 prostate. At early revaluation, a prostate infarct was noticed (white arrow). The relative change in IPSS at 3 months was −92% (<−35%). The patient was satisfied with PAE and symptoms relief at 3 months, 2 years, and during his latest visit 38 months after PAE. Other abbreviation: WI: weighted imaging.