Surgeons were able to identify and remove a greater number of cancerous nodules from lung cancer patients when combining intraoperative molecular imaging (IMI) — using of a contrast agent that makes tumor cells glow during surgery — with preoperative PET scans. Cancer cells glow during surgery. Courtesy of Penn Medicine. To facilitate live imaging during surgery, physicians at the University of Pennsylvania used an NIR contrast agent that makes malignant cells glow. In previous studies, the agent (OTL38) had demonstrated the ability to detect malignant nodules as small as three millimeters. For this study, PET imaging and IMI were combined for 50 patients having surgery to remove lung nodules. All of the patients underwent a preoperative PET scan within 30 days of their procedure. These scans identified a total of 66 nodules. During the operation, IMI identified 60 of the 66 previously known nodules, or 91 percent. In addition, doctors used IMI to identify nine additional nodules that were undetected by the PET scan or by traditional intraoperative monitoring. Between PET and IMI, a total of 75 nodules were identified. Researchers found that PET was accurate in determining if nodules were cancerous in 51 of them (68 percent). By comparison, IMI alone was accurate in 68 cases (91 percent). IMI further improved diagnostics in 30 percent of the patients evaluated with this approach. In about 10 percent of patients, IMI helped surgeons find cancer that would have otherwise been missed by standard imaging like computed tomography (CT) or PET. “This shows the contrast agent is allowing us to remove more cancer from the patient than we would have with PET imaging alone,” said professor Sunil Singhal, M.D. “PET imaging still has an important role to play in developing treatment plans for patients, but given its limitations, it’s clear that IMI with this contrast agent can improve the picture surgeons are seeing,” Singhal said. “That's especially true when you're talking about nodules that are only a centimeter or smaller.” Researchers also say this study lays the groundwork for future research involving the agent OTL38. They're currently evaluating this technology in a formal, multicenter trial that will be the first Phase II study of molecular imaging in the U.S. They're also exploring the effectiveness of additional contrast agents. They will also keep track of patients in the study to find out if these improved surgeries help patients live longer. The research was published in Annals of Surgery (doi: 10.1097/SLA.0000000000002382).