Objective: There is increasing evidence demonstrating efficacy for image guided interventions for the palliation and treatment of a large number of malignancies. Large prospective randomized clinical trials are somewhat deficient. To allow for robust multi-center clinical trials, every effort should be taken to standardize treatment, follow-up evaluation, and image response assessment. Interventional and diagnostic radiologists need to be integral to the development of imaging protocols at the inception of clinical trials.
Linear tumor measurements, as described by RECIST criteria, are likely limited for local regional therapies. Functional/molecular imaging such as PET and DCE-MRI may offer early surrogate end-points for the evaluation of response to therapy, treatment failure and tumor recurrence. To this aim imaging protocols, acquisition, analysis, and quality assurance need to be standardized. A standard lexicon, describing metrics for interpretation, should help augment the literature.

Methods: Here we describe the initiative of the Image Response Assessment Team (IRAT), an NCI designated consortium of 8 Cancer Centers, to develop standardized, consensus driven, imaging protocols for PET, DCE-MRI, and Volumetric CT. These are generated with a 1^st and 2^nd tier of imaging experts within IRAT and a 3^rd tier of invited reviewers. The protocols will then be made publicly available for any future clinical trials.

Results: As a proof of principle, the protocols and over-read process are provided to a company, conducting a multi-center clinical trial investigating radiofrequency ablation for metastatic colorectal carcinoma. A central de-identified image data-base will be generated with the NCI (NCI Archive) for subsequent investigations of imaging endpoints. Data entry of metrics will be standardized for multi-center over-reading of imaging studies. A standard lexicon of terms, describing imaging findings for tumors undergoing ablation, will be utilized.

Conclusion: We describe efforts to standardize imaging for clinical trials investigating image guided intervention. This approach can serve as a template for future clinical trials with deliverables including standard imaging protocols for specified malignancies, standard data entry metrics, and a lexicon of specific descriptors for tumor response.