Joseph Colao BS, Presenter: Nothing to Disclose

Alin Chirindel MD, Abstract Co-Author: Nothing to Disclose

Joo Hyun O MD, Abstract Co-Author: Nothing to Disclose

Steve Cho MD, Abstract Co-Author: Research support, Amgen Inc Research support, Peregrine Pharmaceuticals, Inc Research support, Algeta ASA

Assessment of tumor response to therapy by FDG PET/CT image sets from various time points can be often tedious and time consuming, especially in complex patients with multiple lesions or subtle changes. We developed and applied an integrated color-coded PET/CT image visualization workflow incorporating the tumor uptake at two time points to allow the reader to efficiently and accurately assess the relative PET tumor response to therapy.

Using MIM 5 imaging software (MIM Software TM), we analyzed FDG PET/CT image sets from two time points for 6 melanoma and 6 lymphoma cases. With technical support from MIM, we created a workflow that deformed the baseline PET and CT to the follow-up images. The SUV in each voxel of the deformed baseline PET was substracted from each voxel’s SUV in the follow-up PET. Each PET voxel was assigned a color based on its subtraction value, and the colored images were fused with the follow-up CT image set to create an anatomical view of the relative SUV changes. The colors corresponding to each subtraction value were based on a 20-color scale for positive and negative absolute and percent SUV change from baseline to follow-up. Two readers with third reader adjudication reviewed all 12 cases to determine if the response of the lesions with the greatest SUV values from baseline (max of 2 per organ) were accurately depicted by the color scale by comparing it to traditional gray-scale PET/CT visualization and ROI SUV values.

The number of lesions analyzed per patient ranged from 1 to 5 for each based on the state of the patient’s disease. The readers found that integrated PET/CT color scale images accurately depicted the approximate SUV changes for 26 of the 28 index lesions. The less clear color scale representations occurred because of small errors in the deformable registration in a lung nodule and with development of tumor necrosis.

The integrated color scale PET/CT tumor response image sets provides an efficient and reliable method of determining the approximate tumor SUV changes associated with disease progression or treatment response for the major index lesions in our pilot study of metastatic melanoma or lymphoma patients.

Integrated color scale PET/CT representation can be a helpful aid to quickly judge and approximately quantify tumor response to therapy, especially in cases difficult to assess by current methods.

Colao, J, Chirindel, A, O, J, Cho, S, Integrated PET/CT Color Scale Response Assessment Workflow.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13025376.html