New Imaging Approach May Help Better Map Ovarian Cancer Before Surgery
Somashekhar SP, Shanbhag ER, Jayachandra PH, et al. Comparative Evaluation of [68Ga]Ga-FAPI-04 PET Versus Conventional Imaging for Peritoneal Carcinomatosis Detection in Ovarian Carcinoma: A Multimodal Imaging Study. Journal of Nuclear Medicine. Published online August 27, 2026. doi:10.2967/jnumed.125.271126.
For patients with advanced ovarian cancer, understanding exactly where cancer has spread within the abdomen can be an important part of determining the best treatment approach. New research suggests that an emerging imaging technique may provide doctors with a clearer picture of peritoneal disease before surgery.
A prospective study published in the Journal of Nuclear Medicine compared a newer imaging method called [68Ga]Ga-FAPI-04 PET/CT (FAPI PET) with conventional contrast-enhanced CT (CECT) in 200 patients with primary epithelial ovarian cancer who were being evaluated for cytoreductive surgery.
Why Better Imaging Matters
Ovarian cancer frequently spreads to the peritoneum, the thin tissue lining the abdominal cavity and covering many abdominal organs. Small tumor deposits can be difficult to identify with conventional imaging, particularly in areas such as the upper abdomen, small bowel and mesentery.
Knowing both how much disease is present and where it is located can be especially important when planning cytoreductive surgery, which aims to remove as much visible cancer as possible.
Researchers used the Peritoneal Cancer Index (PCI) to estimate the extent and location of disease seen on each imaging method. They then compared those findings with what surgeons actually observed during surgery.
What Researchers Found
FAPI PET was more sensitive than conventional CT at detecting peritoneal disease.
Overall, FAPI PET demonstrated:
81.8% sensitivity, compared with 54.6% for conventional CT
86% overall diagnostic accuracy, compared with 78% for CT
Better detection of disease in the upper abdomen, with sensitivity of 76.5% compared with 23.5% for CT
Better detection in the small bowel and mesentery, with sensitivity of 50% compared with 31.3% for CT
FAPI PET also estimated the overall amount of peritoneal disease more closely to what surgeons ultimately found. The average PCI was 14.14 with FAPI PET, 10.8 with CT and 15.77 during surgery.
However, conventional CT had higher specificity—96.4% compared with 89.3% for FAPI PET—meaning CT was somewhat better at correctly identifying areas where disease was not present.
What Could This Mean for Patients?
These findings are important because accurately mapping peritoneal disease before surgery may help multidisciplinary teams better plan treatment.
For some patients, surgery may be the appropriate first treatment. For others, chemotherapy before surgery may offer a better approach. More accurate imaging could potentially help physicians identify patients most likely to benefit from cytoreductive surgery while reducing the chance of undergoing a major operation when complete removal of visible disease is unlikely to be achievable.
FAPI PET works differently from conventional CT. The imaging tracer targets fibroblast activation protein (FAP), which is commonly expressed by cancer-associated fibroblasts surrounding many tumors. This can make areas of cancer-associated tissue easier to distinguish from surrounding normal tissue.
More Research Is Needed
While the findings are encouraging, FAPI PET is not currently a replacement for conventional imaging, surgical evaluation or multidisciplinary clinical decision-making.
The study was conducted at a single center, and most participants had already received chemotherapy before imaging. In addition, researchers compared imaging findings with surgeons' assessments during surgery rather than final pathology.
Importantly, the study also did not directly demonstrate that using FAPI PET reduces unnecessary surgeries or improves survival or other patient outcomes. Larger prospective studies will be needed to determine whether the improved imaging accuracy translates into better treatment decisions and outcomes.
The Takeaway
For patients with ovarian cancer that has spread within the abdomen, knowing the location and extent of peritoneal disease can be critical to treatment planning. This study suggests that FAPI PET/CT may provide a more detailed picture of peritoneal disease than conventional CT, particularly in areas that can be challenging for surgeons.
As this technology continues to be studied, it could become another tool to help multidisciplinary teams determine which patients may benefit most from surgery and how best to sequence surgery and chemotherapy.
