Localising occult prostate cancer metastasis with advanced imaging techniques (LOCATE trial): a prospective cohort, observational diagnostic accuracy trial investigating whole-body magnetic resonance imaging in radio-recurrent prostate cancer.

Accurate whole-body staging following biochemical relapse in prostate cancer is vital in determining the optimum disease management. Current imaging guidelines recommend various imaging platforms such as computed tomography (CT), Technetium 99 m (99mTc) bone scan and 18F-choline and recently 68Ga-PSMA positron emission tomography (PET) for the evaluation of the extent of disease. Such approach requires multiple hospital attendances and can be time and resource intensive. Recently, whole-body magnetic resonance imaging (WB-MRI) has been used in a single visit scanning session for several malignancies, including prostate cancer, with promising results, providing similar accuracy compared to the combined conventional imaging techniques. The LOCATE trial aims to investigate the application of WB-MRI for re-staging of patients with biochemical relapse (BCR) following external beam radiotherapy and brachytherapy in patients with prostate cancer.

The LOCATE trial is a prospective cohort, multi-centre, non-randomised, diagnostic accuracy study comparing WB-MRI and conventional imaging. Eligible patients will undergo WB-MRI in addition to conventional imaging investigations at the time of BCR and will be asked to attend a second WB-MRI exam, 12-months following the initial scan. WB-MRI results will be compared to an enhanced reference standard comprising all the initial, follow-up imaging and non-imaging investigations. The diagnostic performance (sensitivity and specificity analysis) of WB-MRI for re-staging of BCR will be investigated against the enhanced reference standard on a per-patient basis. An economic analysis of WB-MRI compared to conventional imaging pathways will be performed to inform the cost-effectiveness of the WB-MRI imaging pathway. Additionally, an exploratory sub-study will be performed on blood samples and exosome-derived human epidermal growth factor receptor (HER) dimer measurements will be taken to investigate its significance in this cohort.

The LOCATE trial will compare WB-MRI versus the conventional imaging pathway including its cost-effectiveness, therefore informing the most accurate and efficient imaging pathway.

LOCATE trial was registered on ClinicalTrial.gov on 18th of October 2016 with registration reference number NCT02935816.

BMC medical imaging. 2019 Nov 15*** epublish ***

Sola Adeleke, Arash Latifoltojar, Harbir Sidhu, Myria Galazi, Taimur T Shah, Joey Clemente, Reena Davda, Heather Ann Payne, Manil D Chouhan, Maria Lioumi, Sue Chua, Alex Freeman, Manuel Rodriguez-Justo, Anthony Coolen, Sachin Vadgama, Steve Morris, Gary J Cook, Jamshed Bomanji, Manit Arya, Simon Chowdhury, Simon Wan, Athar Haroon, Tony Ng, Hashim Uddin Ahmed, Shonit Punwani

Centre for Medical Imaging, University College London, 2nd floor Charles Bell house, 43-45 Foley Street, London, W1W 7TS, UK., Molecular Oncology Group, University College London, Cancer Institute, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK., Division of Surgery and Interventional Science, University College London, 4th floor, 21 University Street, London, WC1E, UK., Oncology Department, University College London Hospital, 235 Euston Road, London, NW1 2BU, UK., Comprehensive Cancer Imaging Centre (CCIC), King's College, London, New Hunt's House, Guy's Campus, London, SE1 1UL, UK., Department of Nuclear Medicine, The Royal Marsden Hospital NHS Foundation Trust, Down's Road, Sutton, SM2 5PT, UK., Histopathology Department, University College London Hospital, 4th Floor, Rockefeller Building University Street, London, WC1 6DE, UK., Institute for Mathematical and Molecular Biomedicine, King's College London, Hodgkin Building, Guy's Campus, London, SE1 1UL, UK., Department of Applied Health Research, University College London, 1-19 Torrington Place, Fitzrovia, London, WC1E 7HB, UK., Department of Cancer Imaging, School of Biomedical Engineering and Imaging Sciences, King's College London, 4th Floor, Lambeth Wing St. Thomas' Hospital, London, SE1 7EH, UK., Institute of Nuclear Medicine, University College London Hospital, 5th Floor Tower, 235 Euston Road, London, NW1 2BU, UK., Urology Department, University College Hospital, Westmoreland Street, 16-18 Westmoreland Street, London, W1G 8PH, UK., Oncology Department, Guy's and St. Thomas' Hospital, Westminster Bridge road, Lambeth, London, SE1 7EH, UK., Department of Nuclear Medicine, St Bartholomew's Hospital, West Smithfield, London, EC1A 7BE, UK., Division of Surgery, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK., Centre for Medical Imaging, University College London, 2nd floor Charles Bell house, 43-45 Foley Street, London, W1W 7TS, UK. .