The purpose of this research study is to learn if differences seen in scans before surgery match differences seen when looking at tumor samples with pathology and genetic tests. In this study we will use Magnetic Resonance Imaging [MRI] and Positron Emission Tomography [PET] scans. No direct clinical benefits will come from the results of this study.

Inclusion Criteria:

• ≥18 years of age on the day of signing the informed consent.
• Histologically confirmed or suspected stage III or IV high-grade serous ovarian cancer.
• Scheduled to undergo primary debulking surgery.

Exclusion Criteria:

• Pregnant patients
• Patients who because of general medical or psychiatric condition, or physiologic status unrelated to the presence of ovarian cancer cannot give valid informed consent
• Patients who are unwilling or unable to undergo MRI including patients with contraindications to MRI such as the presence of cardiac pacemakers or non-compatible intracranial vascular clips, claustrophobia, inability to lie flat for the duration of the study etc.
• Patients with a metallic hip implant or any other metallic implant or device in the pelvis that might distort local magnetic field and compromise quality of MRI/
• Radiotherapy to the abdomen or pelvis within 6 months of the screening visit. Subjects with a current diagnosis of epithelial ovarian tumor of low malignant potential (borderline carcinomas) are not eligible
• Patients with synchronous primary endometrial cancer or a past history of endometrial cancer, unless all of the following conditions are met:
• Stage not greater than IB
• No more than superficial myometrial invasion
• No vascular or lymphatic invasion
• No poorly differentiated subtypes, including serous, clear cell, or other FIGO Grade 3 lesions.
• Patients who have received prior chemotherapy for any abdominal or pelvic tumor are excluded. Patients who have received neoadjuvant chemotherapy prior to their initial debulking are excluded. Patients may have received prior adjuvant chemotherapy for breast cancer.
• With the exception of non-melanoma skin cancer and other specific malignancies as noted above, subjects with other invasive malignancies who had (or have) any evidence of the other cancer present within the last 3 years are excluded.
• Unresolved bowel obstruction.
• History or current evidence of any condition, therapy, or lab abnormality that might confound the results of the study, interfere with patient's participation for the full duration of the study.
• Absence of target lesions (> 2.0 cm) on staging CT
• Patients unlikely to be optimally debulked at surgery (tumor implants in difficult to reach places [i.e. falciform ligament or porta hepatis], suprarenal retroperitoneal lymphadenopathy)