Ovarian Cancer

Fast Facts:

• 2nd most common gynecologic malignancy; most lethal.
• 5th leading cause of death in women.
• Advanced disease @ diagnosis (> 50% Stage III)
• 5-year survival: 45 %

Normal Ovarian Uptake:

Premenopausal: 

• The normal premenopausal ovary typically demonstrates little or no FDG uptake.
• Moderate and even intense metabolic activity in a premenopausal ovary (unilateral or bilateral) is nearly always a normal finding — in the absence of an associated CT abnormality.

Postmenopausal:

• While the normal postmenopausal ovary can demonstrate varying degrees of metabolic activity, further evaluation is recommended for any postmenopausal ovary with uptake above blood pool background – even in the absence of an associated CT abnormality.  

Indications for PET/CT Scan: 

Screening:

No current role in the screening of ovarian cancer.

Diagnosis:

• Very limited role in the diagnosis of ovarian cancer, due to significant false positives and false negatives in the evaluation of primary lesions. 
• There may be a limited role for PET/CT in the evaluation of equivocal lesions in postmenopausal women.

Initial Staging: 

• Initial staging is surgical.
• PET/CT may be of value when neoadjuvant chemotherapy is contemplated.
• The utility of PET/CT for staging lies in its assessment of regional nodes and distant metastatic disease.
• Distant Disease: Most commonly to the liver, peritoneum, lung, pleura, bones and adrenal glands.

Recurrence & Restaging: 

• Restaging suspected recurrence, when CA125 is rising and conventional imaging is negative or equivocal.
• PET/CT alters management in >50% of patients with recurrent disease.
• Distinguishing recurrence from post-therapeutic inflammation.

Assessing Response to Therapy & Prognosis: 

• Early Response: Non-responders can be offered alternative therapy (most commonly in the setting of neoadjuvant chemotherapy).
• Late Response: Assess success or failure of therapy, and ultimate outcome/prognosis.

What We Report:  

Size, metabolic activity & location of the primary lesion (if present) and representative metastatic lesions. 

Primary Lesion:  

• Most ovarian cancer patients presenting for PET/CT imaging have already been surgically staged, so the primary lesion will have been resected. 
• Pre-surgical scans are occasionally ordered to assess early response to neoadjuvant chemotherapy. 
• On occasion, an incidental primary ovarian cancer will be identified.

Metastatic Disease: 

• Direct invasion of adjacent structure/organs.
• Seeding of peritoneal cavity.
• Lymphatic spread to pelvic and paraaortic lymph nodes.
• Hematogenous spread, often to liver and lungs.

Ovarian Cysts:

Non-avid ovarian cysts measuring less than 4.0 cm in premenopausal women are presumed functional, as long as solid elements are not present on the co-registered non-contrast CT images (if greater than 4.0 cm, we recommend a 6-week follow up ultrasound, even though they are still likely functional).

We typically report, “A 3.5 x 3.0 cm non-avid left ovarian cyst is noted, presumed functional in a premenopausal woman.“

Ovarian cysts (as are nearly all cysts in the body) should be non-avid. If an ovarian cyst demonstrates FDG uptake (especially is the uptake is focal), ultrasound correlation is recommended.

In a postmenopausal woman, even a non-avid ovarian cyst warrants close attention. We generally report, “A 3.5 x 3.0 cm non-avid left ovarian cyst is present. Although non-avid, the finding of an ovarian cyst in a postmenopausal woman warrants close clinical assessment.”

False Positives:

• Physiologic Uptake
• Inflammatory lesions
• Endometrioma
• Corpus luteum cyst
• Dermoid

False Negatives:

• Lesions < 8.0 mm
• Low-grade, borderline, and some mucinous lesions
• Cystic lesions (only solid elements are FDG avid)
• Low-volume carcinomatosis