Image Analysis in Oncology
Pharmaceutical companies looking to make quicker GO/NO GO decisions about their oncology drugs are increasingly using advanced imaging techniques in their clinical trials. CT, MRI and PET imaging can be used to provide quantitative or semi-quantitative measurements of lesion size and functional changes over time, allowing for earlier, more accurate classification of drug response.
- RECIST CT (or MRI) to assess tumour burden longitudinally in hepatocellular carcinoma
- DCE-MRI for the pharmacokinetic modelling of solid tumour lesions quantifying disease progression
- Multi-parametric MRI for diagnosis and treatment planning models for prostate cancer
- FDG-PET for semi-quantitative assessment of metabolism in solid tumours.
There are specific challenges in setting up and running each project that are dependent on the application, however, there are some general considerations that can be made.
- Acquisition Design
While RECIST measures are typically made on standard of care images that require minimal site training and interaction, many quantitative measures rely on carefully controlled image acquisition and contrast administration, particularly when the images are collected across multiple sites.
- Project Management
Specific site operation procedures and training, and dedicated project managers for each trial.
- Quality Control
Site specific methods for rapid detection of protocol violations, positioning errors, or poor data quality are developed for each study.
- Image Analysis
Uni-directional and bi-directional measures, such as the RECIST and WHO methods, can fail to measure lesion change in a responsive and precise way. This is in part the inter-observer variability that occurs due to the heterogeneity of many tumours. Volumetric measures are more sensitive to lesion change and allow for earlier, more accurate classification of drug response. IXICO performs traditional methods (RECIST) as well as quantitative image analysis including volumetric and pharmacokinetic measures.
Response Evaluation Criteria in Solid Tumours (RECIST) is an internationally recognized set of published rules regularly used in oncology studies to assess tumour burden longitudinally. These rules define when cancer patients improve (respond), stay the same (stable) and worsen (progress) in response to treatments.
Measurable lesions, identified as ‘Target Lesions’ are chosen at Baseline and a unidirectional measurement is taken of their longest diameter. These individual measurements are then summed to provide an overall assessment on tumour burden which is reviewed at each follow up visit.
Dynamic Contrast Enhanced (DCE) MRI
Dynamic Contrast-enhanced magnetic resonance imaging (DCE-MRI) is widely used in the assessment of anti-angiogenic therapies, where the drug is designed to inhibit tumour growth by causing destruction of the blood vessels which supply it. With the aid of parametric maps, it is possible to estimate pharmacokinetic (PK) parameters that convey information about physiological properties rather than the more standard structural assessments.
Multi-parametric MRI for Prostate Cancer
Multi-parametric MRI is now increasingly being used in diagnostic and treatment models for prostate cancer. It provides an accurate morphometric description of the prostate, which in combination with standardised diagnostic tools is helping to provide much more accurate, minimally invasive, diagnosis of clinically significant cancer and is leading the way in novel non-radical surgical techniques for the direct treatment of prostate cancer.
FDG-PET (SUV & TLG)
Standardized Uptake Value (SUV) is a semi-quantitative assessment commonly used in Position Emission Tomography in combination with the tracer FDG. This assessment differs from standard structural assessments in that it measures changes in metabolic activity. High glucose consumption in tissue is a key characteristic of most cancers. As a result, changes in tumour burden may be derived despite little or no changes in tumour size. Analysis of Total Lesion Glycolysis (TLG) combines both volumetric measurements and metabolic information to provide further information on metabolic activity.