The role of FDG-PET/CT in gynaecological cancers

Abstract

There is now a growing body of evidence supporting the use of fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in gynaecological malignancies. Although this molecular imaging technique is becoming increasingly available, PET/CT remains an expensive imaging tool. It is essential to be familiar with the circumstances in which FDG-PET/CT can add value and contribute to patient management and indeed to know when it is unlikely to be of benefit. It is also important to understand and recognize the potential pitfalls. FDG-PET/CT has been most widely adopted for staging patients with suspected advanced disease or in suspected recurrence, offering a whole-body imaging approach. However, there is great potential for this technique to act as a predictive biomarker of response to treatment, as well as a prognostic biomarker. In addition, FDG-PET images may now be incorporated into radiotherapy planning in order to refine the delineation of dose according to metabolically active sites of disease. This article reviews the literature that provides the evidence for the use of FDG-PET in gynaecological malignancies, identifies areas of real benefit and future potential, and highlights circumstances where there is limited value.

Figures

Figure 1

Patient being investigated for a uterine mass. Sagittal T2 (a) and axial T2 (b) MRI demonstrate a mass arising from the uterus (arrow). The mixed high signal intensity of the mass raised the possibility of a leiomyosarcoma. FDG-PET/CT (c) demonstrated marked FDG uptake within the mass with some central necrosis. After surgical resection, the mass was confirmed to be a benign fibroid that had undergone degenerative changes.

Figure 2

Patient with suspected recurrent ovarian cancer. Contrast-enhanced CT (a) demonstrates 2 sites of recurrent disease along the bowel serosa (arrows) that are very difficult to identify with confidence. The accompanying fused FDG-PET/CT (b) clearly demonstrates the 2 highly metabolically active serosal deposits.

Figure 3

Patient with CA-125 relapse but no clear evidence of recurrence on CT imaging. Fused FDG-PET/CT (a) and accompanying contrast-enhanced CT (b) demonstrate a serosal deposit along a loop of bowel within the stoma (arrow) that is very difficult to appreciate on CT. Repeat imaging after the first cycle of chemotherapy demonstrates a significant reduction in the metabolic activity of the serosal deposit, highly suggestive of a likely responder to treatment.

Figure 4

Patient with recurrent ovarian cancer. Maximum intensity projection (MIP) image of FDG-PET study prior to treatment (a) shows widespread avid uptake at multiple sites of metastatic disease in the neck, chest and abdomen. Two months after the start of chemotherapy, follow-up imaging demonstrates no residual FDG-avid tumour sites, consistent with a complete metabolic response.

Figure 5

Preoperative imaging assessment in a patient with high-grade endometrial carcinoma. Sagittal T2-weighted MRI (a) demonstrates a large tumour mass in the endometrial cavity (arrow), which demonstrated deep myometrial invasion. No enlarged nodes could be seen on MRI in the pelvis or para-aortic positions. The stage on MRI alone was FIGO IB. Coronal fused FDG-PET/CT image (b) demonstrates focal uptake within a para-aortic lymph node, up-staging the patient to FIGO IIIC2.

Figure 6

Patient with a history of high-grade endometrioid endometrial cancer treated 2 years previously presented with a painful left shoulder and suspicious radiograph. FDG-PET/CT confirmed metabolically active disease confined to the left shoulder (arrow).

Figure 7

Patient with FIGO stage IIB squamous cell carcinoma of the cervix. (a) Initial pretreatment MRI (axial T2-weighted image) demonstrates primary cervical tumour with parametrial invasion (long arrow) and left pelvic node involvement (short arrow). No para-aortic lymphadenopathy was demonstrated on abdominal sequences. Fused FDG-PET/CT confirmed highly FDG-avid primary tumour and a single pelvic nodal metastasis (b). Therefore the patient was not suitable for radical surgery and underwent primary chemoradiotherapy treatment. FDG-PET/CT was performed 3 months after completion of treatment (c,d). This demonstrates complete response to the irradiated tumour in the pelvis (c). However, there is disease relapse above the radiotherapy field in the para-aortic region (arrow, d). This finding indicates an adverse prognosis.

Figure 8

Stage IIa adenocarcinoma of the cervix. Sagittal T2-weighted MRI (a) demonstrates an ill-defined tumour in the cervix (arrow). MIP image of an FDG-PET study (b) demonstrates intermediate- to low-grade FDG uptake in the primary tumour (arrow). The level of tumour metabolic activity has been reported to be a predictor of survival.

Figure 9

Patient with advanced cervical carcinoma at presentation. Fused FDG-PET/CT demonstrates a highly metabolically active primary tumour (a). Nodal evaluation is difficult on the fused image (b). However, on the contrast-enhanced CT, there is bilateral nodal necrosis (arrows). These could not be mistaken for the ovaries in this case, as there was ovarian hyperstimulation prior to egg retrieval (d).

Figure 10

Patient with advanced carcinoma of the cervix, imaged 6 months after treatment with primary chemoradiation. Axial T2-weighted MRI (a) demonstrates an area of intermediate T2 signal intensity at the site of the original tumour. This was suspected to be residual disease. Fused FDG-PET/CT (b) demonstrates no evidence of FDG-avid disease. The patient has remained well on clinical follow-up.

Figure 11

Patient with recurrent vulval carcinoma. On the axial T2-weighted MRI (a), there is a large lymphocyst in the left groin due to previous groin node dissection (small arrow). The recurrent tumour is seen in the vulva (large arrow). The patient underwent percutaneous drainage of the lymphocyst. Following this, FDG-PET/CT was undertaken to exclude other sites of disease prior to planning further surgery. Fused FDG-PET/CT confirmed multifocal disease in the vulva (small arrows). Low-grade FDG uptake is seen in the wall of the drained lymphocyst, consistent with probable inflammatory change. No FDG-avid disease was seen elsewhere.