GlucoCEST MRI in Oncology

Overview

The roles of imaging in cancer may be divided into that of diagnosis and tumour detection, staging and assessment of response to treatment. Standard radiological techniques include ultrasound, Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET). A combination of imaging techniques is often necessary to differentiate between cancerous and normal tissue. Traditional imaging techniques identify cancers by their gross appearance and structural/ cellular characteristics, whilst PET do so by tracking glucose metabolism. PET owes its specificity to the high rate of glucose metabolism seen in most cancers. However it is not used routinely due to a lack of availability and high costs. In addition, PET is often used in combination with CT, which imparts a significant diagnostic radiation dose. This can increase an individual's risk of cancer, especially with childhood or early adult exposure. In contrast, MRI is more readily available and does not involve radiation. However its ability to detect cancer by tracking glucose metabolism has not been widely explored. Our group has recently developed a novel MRI technique called Gluco-CEST that can image glucose delivery, uptake and metabolism in cancer, therefore potentially allowing a radiation-free, one-stop imaging service that can be adapted to current generation of MRI scanners. This study aims to optimise the GlucoCEST technique, after which it will be rigorously tested and compared to standard imaging parameters and clinical or pathological reference standards to evaluate its diagnostic and predictive power across a number of cancer populations.

The technique involves administration of glucose solution either orally or intravenously. This is metabolised and concentrated into the intracellular compartment rapidly, which can be detected by GlucoCEST MRI. The abnormally high glucose uptake demonstrated by certain tumours is therefore potential biomarkers. At present this is already being investigated in head and neck cancer patients using oral glucose in a separate study. In this proposal we aim to utilise intravenous administration of glucose, which has been shown in pre-clinical studies to improve GlucoCEST signal, and thus likely to increase the detectability of cancer. This study aims to develop and assess GlucoCEST and other exchange-sensitive MRI measurements (denoted 'exchange-sensitive MRI' hereafter) using intravenous glucose in tumours and metastases, and evaluate its use as an imaging biomarker of tumour and treatment response. This project will: 1. Establish an optimised bolus and infusion protocol of intravenous glucose to maximise exchange-sensitive MRI signal. 2. Assess the reproducibility of exchange-sensitive MRI and initial proof-of-concept study in cancer patients 3. Apply exchange-sensitive MRI in selected cancer types to assess its diagnostic and prognostic power. The initial optimisation study involves investigating the optimal regime of intravenous glucose administration for obtaining the optimal exchange-sensitive MRI signal. The second stage will see exchange-sensitive MRI being applied to patients in different cancer groups to assess its ability for detecting cancer. For the optimisation study, 20 healthy volunteers will be recruited. For the application study 80 patients (20 Hodgkin's lymphoma, 20 head and neck tumour, and 40 glioma) will be investigated. Most of these patients will be due for an MRI as part of their standard care pathway; in these cases exchange-sensitive MRI will be added to the standard imaging sequence. For those who are not otherwise due for MRI, both standard and exchange-sensitive MRI will be acquired. It is expected that the data generated from this study will inform the design of larger trials and will provide the framework for an improved imaging pathway in certain cancer groups in the future.