PET•CT-based Radiation Treatment Planning in a Case of Cervical Carcinoma

High-lesion contrast improves lesion delineation and detection of small residual tumor

Partha Ghosh, MD, Siemens Healthcare, Hoffman Estates, Ill., USA

Case study data courtesy of Jack Wang, MD and Tsu Chen Yen, MD, Chang Gung Memorial Hospital, Linkou, Taiwan

 |  Tue Jun 18 00:00:00 CEST 2013

History
A 63-year-old woman without significant past medical histories presented with post-menopausal vaginal bleeding for 2 years. Gynecological examination revealed a bulky cervical mass without direct pelvic side wall invasion. A cervical biopsy showed very poorly differentiated squamous cell carcinoma with extensive necrosis.

The patient underwent fludeoxyglucose F18* (18F FDG) PET•CT, as well as MRI for primary staging.

 

*Siemens' PETNET Solutions is a manufacturer of fludeoxyglucose F 18 injection (18F FDG). Indication and important safety information as approved by the US Food and Drug Administration can be found at the bottom of the page for 18F FDG, adult dose 5-10 mCi, administered by intravenous injection.

 

Examination Protocol
Scanner: Biograph mCT
Dose: 10 mCi 370/MBq 18F FDG
Scan Delay: 150 min post injection
Parameters: 4 min/bed PET acquisition

Diagnosis

The study was performed on Biograph™ mCT 64 with the industry’s finest** volumetric resolution, which improves lesion margin delineation for more accurate Gross Tumor Volume (GTV) determination. High-lesion contrast achieved using ultraHD•PET (Time of Flight and Point Spread Function (PSF) reconstruction combined) improves lesion delineation, especially for small primary tumors and recurrences, as well as for small lymph node metastases.

PET showed increased metabolic activity in the cervix with a maximum standardized uptake value (SUVmax) of 27 (Figure 1). No nodal or distant metastasis was found. MRI revealed a 74 mm x 71 mm x 63 mm mass within the cervix. There was no enlargement of the pelvic nodes, para-aortic nodes and inguinal nodes. Final clinical staging was cT2b2N0M0 by 2009 American Joint Committee on Cancer staging system (FIGO stage IIb2).
A definitive concurrent chemo-radiotherapy (CCRT) with weekly cisplatin (40mg/ m2) was arranged. Radiation was delivered by conventional four-field box technique. Doses of large-field radiation to the whole pelvis were 45 Gy/25 fractions (Figure 2A), followed by a true pelvis boost, including the whole uterus, to a total dose of 54 Gy/30 fractions (Figure 2B). Brachytherapy was administered as 5 fractions with 4 Gy/fraction to point A.

Overall, the patient tolerated combined treatment well and did not require any unplanned treatment breaks. Acute grade II diarrhea was noted during CCRT. At the end of treatment, the surface of the cervix showed complete tumor regression with little granulation change by clinical pelvic examination. MRI and PET follow-up scans were done during the fourth week of treatment and 2 months after completing treatment.
The images on the fourth week illustrated a partial response of the primary tumor (Figure 3B). However, PET•CT findings of post-CCRT study suggested residual tumor over the fundus of uterus (Figure 3C). High-lesion contrast achieved on Biograph mCT was instrumental in the detection of a small residual tumor in post-chemoradiation study.
Based on the PET•CT findings and the post-CCRT status of this patient, a salvage radical hysterectomy was performed one month later. The final pathology revealed a 1.5 x 1 cm tumor mass over the endometrium with invasion to 10% of the myometrial wall thickness. The other sites, including cervix and parametrium, were all cancer-free. This patient is still alive without disease recurrence.
This case illustrates the value of 18F FDG PET•CT for radiation therapy planning and therapy response evaluation in cervical carcinoma. PET•CT demonstrated high sensitivity for detection of small residual tumor after CCRT and helped guide the salvage therapy.

 

* Fludeoxyglucose F 18 Injection

 

INDICATIONS AND USAGE


Fludeoxyglucose F 18 injection (18F FDG) is indicated for positron emission tomography (PET) imaging in the following setting:
Oncology: For assessment of abnormal glucose metabolism to assist in the evaluation of malignancy in patients with known or suspected abnormalities found by other testing modalities, or in patients with an existing diagnosis of cancer.

 

IMPORTANT SAFETY INFORMATION

Radiation Risks
Radiation-emitting products, including fludeoxyglucose F 18 injection, may increase the risk for cancer, especially in pediatric patients. Use the smallest dose necessary for imaging and ensure safe handling to protect the patient and health care worker.

Blood Glucose Abnormalities
In the oncology and neurology setting, suboptimal imaging may occur in patients with inadequately regulated blood glucose levels. In these patients, consider medical therapy and laboratory testing to assure at least two days of normoglycemia prior to fludeoxyglucose F18 injection administration.

Adverse Reactions
Hypersensitivity reactions with pruritus, edema and rash have been reported; have emergency resuscitation equipment and personnel immediately available.

 

Full Prescribing Information for Fludeoxyglucose F 18 Injection

 

Fludeoxyglucose F 18 Injection is manufactured by Siemens' PETNET Solutions, 810 Innovation Drive, Knoxville, TN 39732
 

**Based on competitive information available at time of publication. Data on file.

The statements by Siemens customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical" hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.