F-18-FDG Imaging Using Dual-Head Coincidence Positron Emission Tomography in Patients with Head and Neck Cancer / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: An accurate, preoperative assessment of tumor extent and lymph node involvement is necessary to plan and tailor therapy for patients with head and neck cancer. Metabolic imaging with tluorine-18-fluorodeoxyglucose (FDG) is a good method to detect primary cancers in the head and neck and to assess the involvement of lymph nodes, but it is not widely available because of high cost of positron emission tomography (PET). Recently, an alternative method for using FDG was developed: the coincidence detection PET (CoDe PET) using a gamma camera. The aim of this study was to evaluate the clinical utility of FDG CoDe PET using a gamma camera in patients with head and neck cancer. MATERIALS AND METHODS: Thirty FDG CoDe PET studies were performed in 7 patients before therapy and 19 patients after therapy with various head and neck cancers (Age : 25- 79 years, mean age : 50+/-13 years, 18 men, 8 women). All patients had fasted for 6 to 12 hours and were injected 1 1 l to 370 MRq of F-18-FDG 1 hour before imaging. With the exception of the physiological FDG uptake, all visually detectable focal FDC uptake in the primary cancer site or in the neck was considered positive. FDG CoDe PET studies were correlated with CT/MRI. The standard procedure for detecting the presence of disease was the combinations of repeated MRIs, 3 months of follow-up clinical evaluation and the result of a needle aspiration cytology or biopsy. RESULTS: FDG CoDe PET had a detcction rate that was comparable to that of CT/MRI in the pre-therapy group. However, in the post-therapy group, FDG CoDe PET could differentiate residual/recurrence of tumor from radiation change more accurately than could MRI. But, it had a less accurate detection rate for cervical metastases because of asymmetric neck muscle uptake. CONCLUSION: FDG CoDe PET is a sensitive and cost-effective method to detect primary tumor and lymph node involvement in primary head and neck cancers. It is also useful in differentiating residual tumor or tumor recurrence from post-therapy changes in patients with head and neck cancers.

The Role of Camera-Based Coincidence Positron Emission Tomography in Nodal Staging of Non-Small Cell Lung Cancer / 결핵

BACKGROUND: It is very important to determine an accurate staging of the non-small cell lung cancer(NSCLC) for an assessment of operability and it's prognosis. However, it is difficult to evaluate tumor involvement of mediastinal lymph nodes accurately utilizing noninvasive imaging modalities. PET is one of the sensitive and specific imaging modality. Unfortunately PET is limited use because of prohibitive cost involved with it's operation. Recently hybrid SPECT/PET (single photon emission computed tomography/positron emission tomography) camera based PET imaging was introduced with relatively low cost. We evaluated the usefulness of coincidence detection (CoDe) PET in the detection of metastasis to the mediastinal lymph nodes in patients with NSCLC. METHODS: Twenty one patients with NSCLC were evaluated by CT or MRI and they were considered operable. CoDe PET was performed in all 21 patients prior to surgery. Tomographic slices of axial, coronal and sagittal planes were visually analysed. At surgery, mediastinal lymph nodes were removed and histological diagnosis was performed. CoDe PET findings were correlated with histological findings. RESULTS: Twenty of 21 primary tumor masses were detected by the CoDe PET. Thirteen of 21 patients was correctly diagnosed mediastinal lymph node metastasis by the CoDe PET. Pathological NO was 14 cases and the specificity of NO of CoDe PET was 64.3%. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of N1 node was 83.3%, 73.3%, 55.6%, 91.7%, and 76.2% respectively. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of N2 node was 60.0%, 87.5%, 60.0%, 87.5%, and 90.0% respectively. There were 3 false negative cases but the size of the 3 nodes were less than 1cm. The size of true positive nodes were 1.1cm, 1.0cm, 0.5cm respectively. There were 1 false positive among the 12 lymph nodes which were larger than 1cm. False positive cases consisted of 1 tuberculosis case, 1 pneumoconiosis case and 1 anthracosis case. CONCLUSION: CoDe PET has relatively high negative predictive value in the enlarged lymph node in staging of mediastinal nodes in patients with NSCLC. Therefore CoDe PET is useful in ruling out metastasis of enlarged N3 nodes. However, further study is needed including more number of patients in the future.