Over the past 20 years the pace of technological developments in medical imaging has been relentless, improving our understanding of disease processes and better quantifying treatment effects. Advanced imaging techniques in computed tomography (CT), magnetic resonance imaging (MRI) along with functional imaging technologies such as positron emission tomography (PET) hybridised with CT or MRI acquisitions, coupled with molecular tracers to assess metabolic processes has led to annual increases of over 10% in Radiology output (with similar increases in complexity) and has ultimately delivered radiology sub specialisation.
The UK healthcare system has been at the forefront of these patient care innovations, exemplified by the central role imaging departments now have in the patient journey by enhancing diagnostic accuracy, assessing treatment responses and the role of imaging based screening for disease; such as high risk smokers by CT scanning for early asymptomatic lung cancer. The UK radiologist sub specialist workforce has attained a position as a credible and internationally respected community shored up by high standards of training, continuing professional development and the governance/regulatory framework provided and enforced by the Royal College of Radiologists and the General Medical Council.
Not only has medical imaging and the field of radiology benefited from the contributions of countless physicists, mathematicians, material scientists and molecular biologists to name but a few, IT and the Internet has enabled an explosion in Teleradiology, attracting radiologists with remote working, pay per fee models and ability to sub specialise for more than one source. For CROs, this has given greater access to uploading trial imaging, but perhaps more crucially, access to leading trial reporting specialists renowned for publications and research.
Subsequently, when a clinical trial demands the highest in quality & credibility, where better to have the radiology element reviewed than in the UK.
The life sciences industry has recognised the valuable contribution medical imaging techniques can have in pharmaceutical or medical device clinical trials, imaging in clinical trials has grown by over 700% since the early 2000’s. With the growth of medical imaging in both pre-clinical and clinical phase research, imaging endpoints are now routinely requested by regulatory bodies, thus adding news layers of complexity to already busy trial schedules.
It is not surprising why there has been this astonishing growth of imaging in drug development, when one considers the non-invasive aspects, allowing tissues to be studied that are difficult to biopsy. The facilitation of precision medicine by virtue of screening and stratifying patients into those groups who are more likely respond to the therapeutic product under test, usually in the paradigm of molecular level disease setting. Hence drug development timelines can be shortened, overall budgets are reduced and regulatory approval pathways accelerated.
The imaging aspects of a clinical trial will involve the scanning of patient volunteers to strict protocol guidelines, these are often archived at the local scanning centre/hospital institution as well as being exported to a single site known as the core imaging laboratory for a centralised review. There is full anonymisation of the data sets with only code identification, these imaging data sets undergo reading by carefully selected experienced radiologists against the study criteria, often referred to as the imaging manual. Any measurements should be recorded, allowing an audit trail and the overall assessment of response is made against hard objective specifics laid out in the imaging manual. To maintain quality, many core laboratories operate a 2 + 1 model, where 2 radiologists will independently report on the same study, for a further radiologist to perform an adjudicator role by only submitting the analysis closest to perceived ground truth.
Imaging plays a role in every stage of the process of drug development. Currently oncology clinical trials are the largest utiliser of imaging, in phase I clinical trials initial evidence for anti-neoplastic effect can be sought by size reduction in solid tumours using CT scans. Also pharmacokinetic and pharmacodynamic data can be elucidated. In phase II studies, drug safety and efficacy within a defined population is augmented by imaging often using standardised response criteria. Once such is the response evaluation criteria in solid tumours (RECIST), allowing response outcomes to be categorised as progressive disease, stable, partial and complete response. RECIST is undertaken by summating dimensional measurements of lesions into target and non-target lesions and following these over serial scans on each patient. Hence it acts as surrogate endpoint in a clinical trial rather than the ultimate proof of anti-cancer drug effect of improved clinical symptoms and survival.
Tumour size measured before and after therapy is considered an accepted means of assessing treatment response. However it is known that many novel therapies do not necessarily result in immediate tumour size reduction, thus allowing the functional imaging modalities of PET-CT and PET-MRI to look for metabolic changes such as reduction of glucose metabolism in atum our site following the rapy prior to any anatomical change. Other biological correlates of tumour behaviour can be quantified via imaging namely blood flow, vascular permeability, cellularity and hypoxia utilising these functional techniques.
To maintain quality, in house proprietary software is often used by core laboratories to significantly improve the evaluation of clinical imaging trial data. For example image analysis software is used to guide a radiologist through the study read, pre-processing and segmenting regions of interest in keeping with the imaging manual, thus reducing deviations and reducing reader bias from creeping into the final analysis.
The remarkable progression in the field of clinical radiology and medical imaging has provided an invaluable contribution to clinical research. Through technology and systems advancement, the high quality and specialism associated with UK expertise has become much more accessible to international CRO’s in order to meet their needs and requirements in fulfilling the rigorous aspects of imaging in clinical trials. The life sciences industry has recognised the valuable contribution medical imaging techniques can have in pharmaceutical or medical device clinical trials.
“The life sciences industry has recognised the valuable contribution medical imaging techniques can have in pharmaceutical or medical device clinical trials.”
About The Author
Pauric Greenan is an experienced PACS consultant that has been PACS lead on several high-profile PACS projects in both the UK and Ireland. Pauric is internationally available for PACS consulting. Contact him here for more details.
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