Elsevier

Magnetic Resonance Imaging

Volume 67, April 2020, Pages 50-58
Magnetic Resonance Imaging

Original contribution
DWI and PRECISE criteria in men on active surveillance for prostate cancer: A multicentre preliminary experience of different ADC calculations

https://doi.org/10.1016/j.mri.2019.12.007Get rights and content

Highlights

  • ADC values are inversely correlated with the PRECISE score.

  • Lower ADC values on follow-up imaging are associated with radiological progression.

  • The role of ADC in serial MR scans during AS should be further investigated.

Abstract

Purpose

The PRECISE score estimates the likelihood of radiological progression in patients on active surveillance (AS) for prostate cancer (PCa) with serial multiparametric magnetic resonance imaging (mpMRI). A PRECISE score of 1 or 2 denotes radiological regression, PRECISE 3 indicates stability and PRECISE 4 or 5 implies progression.

We evaluated the inter-reader reproducibility of different apparent diffusion coefficient (ADC) calculations and their relationship to the PRECISE score.

Material and methods

Baseline and follow-up scans (on the same MR systems) of 30 patients with visible lesions from two different institutions (University College London and Sapienza University of Rome) were analysed by two radiologists (one from each site). The PRECISE score was initially assessed in consensus. At least six weeks later, to reduce the likelihood of being influenced by the consensus PRECISE reading, each radiologist independently calculated ADC for the following: lesion, non-cancerous tissue and urine in the bladder. Normalised ADC ratios were calculated with respect to normal prostatic tissue (npADC) and urine. Spearman's correlation (ρ), intraclass correlation coefficients (ICC), differences in ADC and ROC curves were computed.

Results

Interobserver reproducibility was very good (ρ > 0.8; ICC > 0.90). Lesion ADC (0.91 vs 0.73 × 10−3 mm2/s; p=0.025) and npADC ratio (0.68 vs 0.53; p=0.012) at follow-up mpMRI were different between patients with radiological regression or stability vs progression. Cut-offs of 0.77 × 10−3 mm2/s (lesion ADC) and 0.59 (npADC ratio) could differentiate the two groups (area under the curve: 0.74 and 0.77, respectively).

Conclusion

The ADC, npADC ratio and the PRECISE score should be recorded for MRI-based AS.

Introduction

Prostate cancer (PCa) is the most commonly diagnosed solid organ cancer in men in the United Kingdom, with around 40,000 cases diagnosed each year [1].

Patients with PCa confined to the prostate are classified into low, intermediate and high-risk categories and active surveillance (AS) is recommended for low or intermediate-risk disease [1].

The standard AS programmes include repeated blood tests, digital rectal examination and standard biopsy.

There is compelling evidence that multiparametric magnetic resonance imaging (mpMRI) shows potential in identifying candidates for AS, who may have little benefit from therapy, but still need to be monitored to allow prompt curative treatment if the disease shows signs of becoming harmful (radiological progression) [[2], [3], [4]].

Sanguedolce and colleagues explored which baseline mpMRI features might be helpful for the refinement of AS inclusion criteria in 135 patients and concluded that a Prostate Imaging Reporting And Data System (PI-RADS) score > 3 and an index lesion >10 mm were strongly associated with patient withdrawal from the AS programme [5].

Quantitative assessment of the change in diffusion-weighted imaging (DWI) over time is of interest as a way to detect who develop clinically significant disease whilst on surveillance [4,[6], [7], [8]]. This technique measures the diffusion of water molecules within the extracellular space by the calculation of a quantitative parameter called apparent diffusion coefficient (ADC) [9]. Because cancer cells are more tightly packed than benign cells, diffusion of water is restricted in the former and this corresponds to a higher signal on DWI and decreased signal on the ADC map (i.e. a lower ADC value than normal tissue). It has been reported that the ADC is a significant predictor of time to adverse histology on biopsy or radical treatment for PCa during AS [10]. However, the current reporting of studies of mpMRI during AS lacks rigour and standardisation [2].

In the United Kingdom, the National Institute for Health and Care Excellence (NICE) guidelines recommend the use of serial mpMRI during AS, but they do not clearly report how often mpMRI should be performed and how serial mpMRI findings should be interpreted [11].

To address this need, the PRECISE (Prostate Cancer Radiological Estimation of Change in Sequential Evaluation) criteria were published in 2016 [12]. The aim of these recommendations, which are based on international expert consensus, is to facilitate robust data collection from serial mpMRI during AS and to distinguish natural variability from changes indicating true radiologic progression of PCa.

The PRECISE criteria recommend scoring the likelihood of radiological progression on follow up scans using a 1-to-5 scale (PRECISE score). A score of 1–2 indicates regression of a previously visible lesion, 3 denotes stability and 4–5 corresponds to radiological progression (Table 1).

We conducted this pilot study in two academic centres (University College London -UCL- and Sapienza University of Rome), both highly experienced in prostate mpMRI reporting in order to address the following question: can DWI be used to differentiate those patients whose cancer progresses from those with stable disease?

In order to do this, we firstly evaluated the inter-reader reproducibility of different ADC calculations from serial prostate MR scans and then explored if and how these are related to the PRECISE score.

Section snippets

Material and methods

In this two-centre, retrospective study patient records and MR images were reviewed as part of an audit routinely performed for the internal evaluation of the AS service (Fig. 1).

Results

A total of 30 patients (fifteen scanned on 1.5 T and fifteen on 3 T MR systems) were included in this study.

The median interval between baseline and follow-up mpMRI was 14 months (IQR: 12–18.75).

There were 26/30 (87%) lesions in the PZ and 4/30 (13%) in the TZ.

The median ROI size (averaged between the two readers) was 15 mm2 (IQR: 0.11–0.24) for baseline and 20 mm2 (IQR 0.14–0.41) for follow-up mpMRI.

Table 2 shows the descriptive characteristics of all patients included in the study. Overall,

Discussion

There is a need for reliable risk-assessment tools that can support the assessment of stability for patients on AS, and MRI-derived parameters such as the ADC represent an encouraging step in this direction.

The main finding from our study is that the absolute ADC value of the lesion and the npADC ratio (normalised to non-cancerous prostatic tissue) on follow-up imaging are significantly different according to the presence of radiological progression, defined as per PRECISE recommendations (i.e.

CRediT authorship contribution statement

Francesco Giganti: Conceptualization, Methodology, Formal analysis, Investigation, Data curation, Writing - original draft, Funding acquisition. Martina Pecoraro: Conceptualization, Investigation, Data curation, Writing - review & editing. Davide Fierro: Software. Riccardo Campa: Data curation. Francesco Del Giudice: Data curation. Shonit Punwani: Writing - review & editing. Alex Kirkham: Writing - review & editing. Clare Allen: Writing - review & editing. Mark Emberton: Supervision, Funding

Acknowledgements

We thank all the patients who greatly contributed to the realisation of this study.

This study has received funding by the European School of Radiology (ESOR) under the umbrella of the 2019 BRACCO fellowship and the ERASMUS+ programme (University College London).

  • Dr. Francesco Giganti is funded by the UCL Graduate Research Scholarship, the Brahm PhD scholarship in memory of Chris Adams, the ESOR 2019 BRACCO Imaging fellowship and the ERASMUS+ programme (UCL).

  • Prof. Shonit Punwani receives research

References (22)

  • A.A. Malayeri et al.

    Principles and applications of diffusion-weighted imaging in cancer detection, staging and treatment follow-up

    Radiographics

    (2011)
  • Cited by (0)

    1

    These authors share joint senior authorship.

    View full text