Ex vivo1H and 31P magnetic resonance spectroscopy as a means for tumor characterization in ovarian cancer patients

Abstract

We aimed to determine whether cells obtained from malignant ovarian tumors had different exvivo 1H-and31P(phosphorus-31)-magnetic resonance (MR) spectra compared to cells obtained from benign ovarian cysts. In addition, we aimed to assess the metabolic effects of chemotherapy on malignant cells obtained from peritoneal effusions of ovarian cancer patients. We included 20ovarian cancer patients undergoing explorative laparotomy for tumor resection, 15patients undergoing oophorectomy for benign ovarian cysts and 8patients with advanced ovarian cancer with cancerous peritoneal effusion undergoing palliative percutaneous drainage. Ovarian and metastatic tissues were obtained from all patients undergoing laparotomy and analyzed using 1H magnetic resonance spectroscopy (MRS). Cancerous cells from peritoneal effusions were incubated with 3different anti-mitotic drugs (paclitaxel, cisplatin and carboplatin) at LC50 and the consequent metabolic changes were monitored using 31P-MRS. 1H-MRS revealed significantly higher intracellular lactate levels in cells obtained from ovarian tumors, most prominently in the moderately to poorly differentiated histological types, while total choline (Chol) compounds were higher in the moderately to poorly differentiated subgroup only. Ovarian cancer cells obtained from peritoneal effusions showed a significantly decreased glycerophosphocholine (GPC), glycerophosphoethanolamine (GPE) and uridine diphospho-sugar (UDPS) levels following exvivo exposure to all 3 anti-mitotic drugs. Exvivo 1H-MRS identified significant metabolic differences between cells obtained from ovarian tumors compared to those originating in benign ovarian cysts, including increased lactate and total choline compound levels. The 31P-MRS technique allowed characterization and monitoring of metabolic changes occurring in ovarian cancer cells in response to chemotherapy.