2.2. CT Scan Acquisition and Review
tumor, SD, Tumors, PD, primary lung tumor
DISEASE, TUMOR, METASTATIC DISEASE, TUMORS
The baseline and first FU CT scans were acquired according to the standard body scanning protocols at our institution. All CT scans used a GE Light Speed CT scanner (GE Healthcare, Milwaukee, WI, USA), with an intravenous iodinated contrast injection obtained at the portal venous phase for the chest, abdomen, and pelvis, with the images reconstructed using a 2 or 2.5 mm slice thickness. Imaging of the brain included pre- and post-IV contrast scans from a CT and/or MRI. All follow-up scans were acquired using the same protocol.Two board-certified oncology radiologists, with 8 and 20 years of experience in tumor burden measurements/response assessments, performed the imaging analysis while blinded to the patient outcome data. Any question from the imaging analysis was resolved by the consensus of the two radiologists. For the baseline CT, the radiologists measured the largest dimension of the primary lung tumor, documented the sites of metastatic disease, and summed the total “number of involved organs” as an estimate of the disease burden (Next, the baseline and first FU CT were compared to assess the treatment response as per the Response Evaluation Criteria in Solid Tumors criteria (RECIST v1.1) [According to RECIST V1.1, progressive disease (PD) was at least a 20% increase in the sum of the diameters of the target lesions (with the sum also demonstrating an absolute 5 mm increase in size). A complete response (CR) was the disappearance of all target lesions and reduction of pathological lymph nodes to a <10 mm short axis. A partial response (PR) was at least a 30% decrease in the sum of the diameters of the target lesions. A stable disease (SD) had neither sufficient shrinkage to qualify for PR nor was sufficient to qualify for PD. Patients were dichotomized into the “progressive disease, PD” group or “disease control, DC” group if they demonstrated CR, PR, or SD.