Impact of neoadjuvant androgen deprivation therapy on magnetic resonance imaging features in prostate cancer before radiotherapy

Abstract

Background and purpose: In locally advanced prostate cancer (PC), androgen deprivation therapy (ADT) in combination with whole prostate radiotherapy (RT) is the standard treatment. ADT affects the prostate as well as the tumour on multiparametric magnetic resonance imaging (MRI) with decreased PC conspicuity and impaired localisation of the prostate lesion. Image texture analysis has been suggested to be of aid in separating tumour from normal tissue. The aim of the study was to investigate the impact of ADT on baseline defined MRI features in prostate cancer with the goal to investigate if it might be of use in radiotherapy planning.

Materials and methods: Fifty PC patients were included. Multiparametric MRI was performed before, and three months after ADT. At baseline, a tumour volume was delineated on apparent diffusion coefficient (ADC) maps with suspected tumour content and a reference volume in normal prostatic tissue. These volumes were transferred to MRIs after ADT and were analysed with first-order -and invariant Haralick -features.

Results: At baseline, the median value and several of the invariant Haralick features of ADC, showed a significant difference between tumour and reference volumes. After ADT, only ADC median value could significantly differentiate the two volumes.

Conclusions: Invariant Haralick -features could not distinguish between baseline MRI defined PC and normal tissue after ADT. First-order median value remained significantly different in tumour and reference volumes after ADT, but the difference was less pronounced than before ADT.

Keywords: Androgen deprivation; GLCM; Prostate; Texture; mpMRI.

Conflict of interest statement

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ulrika Björeland, Lars Beckman, Sara Strandberg, Mikael Skorpil, Katrin Riklund and Camilla Thellenberg-Karlsson declare that they have no conflict of interest. Joakim Jonsson and Tufve Nyholm are shareholders in NONPI Medical AB. Lennart Blomqvist is cofounder of Collective Minds Radiology (www.cmrad.com).

© 2021 The Author(s).

Figures

Fig. 1

Fiducial markers in CT (top row) and T2w MRI (bottom row) after ADT in three different locations. Fiducial markers are inserted after ADT. VOIs indicate the tumour VOI and reference VOI registered with r + DIR techniques from ADC at baseline.

Fig. 2

Multiparametric MRI (ADC, T2w and Ktrans from DCE MRI) from a patient in the study. a-c are baseline, and d-f are post-ADT. White arrows indicate registration order. PSA at baseline: 48 ng/ml, PSA post ADT: 0.1 ng/ml. a) ADC at baseline: Tumour VOI = 0.5 × 10−3 mm2/s, Reference VOI = 1.5 × 10−3 mm2/s. b) T2w at baseline, volumes: CTV = 55 cm3, Tumour VOI = 2.9 cm3, Reference VOI = 5.7 cm3. c) Ktrans at baseline: Tumour VOI = 0.11 min−1, Reference VOI = 0.02 min−1. d) ADC after ADT: Tumour VOI = 1.0 × 10−3 mm2/s, Reference VOI = 1.0 × 10−3 mm2/s. e) T2w after ADT, volumes: CTV = 35 cm3, Tumour VOI = 1.4 cm3, Reference VOI = 4.3 cm3. f) Ktrans after ADT: Tumour VOI = 0.02 min−1, Reference VOI = 0.03 min−1.

Fig. 3

Median values in box plot representation before and after ADT for different imaging occasions and different modalities. The result from comparison between different VOIs by Wilcoxon Signed Rank test with significance levels: Not Significant –, * (p = 0.8 ± 0.1 × 10−3 mm2/s, Tumour VOI after ADT = 0.9 ± 0.1 × 10−3 mm2/s, Reference VOI at baseline = 1.2 ± 0.2 × 10−3 mm2/s and Reference VOI after ADT = 1.0 ± 0.1 × 10−3 mm2/s. Median Ktrans: Tumour VOI at baseline VOI = 0.12 ± 0.07 min−1, Tumour VOI after ADT = 0.04 ± 0.02 min−1, Reference VOI at baseline = 0.08 ± 0.05 min−1 and Reference VOI after ADT = 0.04 ± 0.04 min−1.