In vivo imaging of cellular proliferation in renal cell carcinoma using 18F-fluorothymidine PET.

OBJECTIVES: The ability to measure cellular proliferation non-invasively in renal cell carcinoma may allow prediction of tumour aggressiveness and response to therapy. The aim of this study was to evaluate the uptake of 18F-fluorothymidine (FLT) PET in renal cell carcinoma (RCC), and to compare this to 18F-fluorodeoxyglucose (FDG), and to an immunohistochemical measure of cellular proliferation (Ki-67). METHODS: Twenty seven patients (16 male, 11 females; age 42-77) with newly diagnosed renal cell carcinoma suitable for resection were prospectively enrolled. All patients had preoperative FLT and FDG PET scans. Visual identification of tumour using FLT PET compared to normal kidney was facilitated by the use of a pre-operative contrast enhanced CT scan. After surgery tumour was taken for histologic analysis and immunohistochemical staining by Ki-67. RESULTS: The SUVmax (maximum standardized uptake value) mean±SD for FLT in tumour was 2.59±1.27, compared to normal kidney (2.47±0.34). The mean SUVmax for FDG in tumour was similar to FLT (2.60±1.08). There was a significant correlation between FLT uptake and the immunohistochemical marker Ki-67 (r=0.72, P<0.0001) in RCC. Ki-67 proliferative index was mean ± SD of 13.3%±9.2 (range 2.2% - 36.3%). CONCLUSION: There is detectable uptake of FLT in primary renal cell carcinoma, which correlates with cellular proliferation as assessed by Ki-67 labelling index. This finding has relevance to the use of FLT PET in molecular imaging studies of renal cell carcinoma biology.

Impact of ¹8F-FDG-PET in decision making for liver metastectomy of colorectal cancer.

BACKGROUND: The ability of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) to impact on management of patients with recurrent colorectal cancer is high. However, direct impact of FDG-PET on surgical management of patients with potentially resectable hepatic metastases is limited. METHODS: FDG-PET scans of patients with colorectal cancer at Austin Hospital in a 2-year period were retrospectively evaluated. Data were collected on patient demographics, scan indication and sites of disease pre- and post-PET. Results of standard imaging tests and FDG-PET scans were analysed. The potential impact of FDG-PET on proposed surgical management plans was assessed by an experienced surgeon. RESULTS: There were 585 FDG-PET scans performed on 470 patients (309M : 161F, mean age 61.9 years) with colorectal cancer. Hepatic metastases were identified on standard imaging in 232 (39.7%) patients, and FDG-PET confirmed hepatic metastasis in 203 cases, including 22 cases with new lesions, and clarified presence of disease in 34/37 (92%) cases with equivocal standard imaging. In 54 patients, FDG-PET was performed for disease assessment before hepatic resection. FDG-PET had substantial management plan impact in 36/54 (66.7%) patients. CONCLUSIONS: FDG-PET can profoundly impact on the management plan of patients with colorectal cancer who may be suitable for hepatic metastectomy.

PET changes management and improves prognostic stratification in patients with recurrent colorectal cancer: results of a multicenter prospective study.

UNLABELLED: The aims of our study were to examine the impact of PET in changing management in patients with proven or suspected colorectal cancer recurrence and to assess the impact of management change on disease-free survival. METHODS: Symptomatic patients with a residual structural lesion suggestive of recurrent tumor (group A) or patients with pulmonary or hepatic metastases considered to be potentially resectable (group B) underwent PET scans. Pre-PET management plans were documented by referring clinicians unaware of the PET results, and follow-up to 12 mo was performed to determine actual management and clinical outcomes. RESULTS: A total of 191 patients (118 men and 73 women; mean age, 66 y) were studied. PET detected additional sites of disease in 48.4% of patients in group A and in 43.9% of patients in group B. A change in planned management was documented in 65.6% of group A and in 49.0% of group B patients. These management plans were implemented in 96% of patients. Follow-up data in group A showed progressive disease in 60.5% of patients with additional lesions detected by PET, compared with conventional imaging, and in 36.2% of patients with no additional lesions detected by PET (P=0.04). In group B, progressive disease was identified in 65.9% of patients with additional lesions detected by PET and in 39.2% of patients with no additional lesions detected by PET (P=0.01). PET also provided valuable prognostic information on patients stratified into curative- or palliative-intent groups. CONCLUSION: These data demonstrate the significant impact of PET on management and outcomes in patients with suspected recurrent colorectal cancer.

Assessment of the role of FDG PET in the diagnosis and management of children with refractory epilepsy.

PURPOSE: We performed a retrospective analysis of the results of FDG PET scans in children with refractory epilepsy referred to our centre over an 8-year period, with a view to ascertaining the impact of FDG PET on subsequent patient management. METHODS: A questionnaire was used to assess the impact of FDG PET scan on diagnosis, management and clinical decision-making processes for epilepsy surgery from the managing clinician's perspective. FDG PET scan results were also compared with MRI, EEG and SPECT results and coded according to whether the FDG PET scan provided independent information and localisation of epileptogenic regions. RESULTS: A total of 118 eligible patients under the age of 14 years were identified, with questionnaires being completed on 113 evaluable patients (96%). The pre-PET management plan consisted of consideration for surgery in 92 patients (81%) and medical therapy for the remaining 21 patients (19%). Managing physicians rated FDG PET as providing information additional to that obtained with other investigations regarding epileptogenic sites in 88 patients (77%). FDG PET had either a minor or a major impact on clinical management in 58 patients (51%), principally with regard to surgical candidacy. CONCLUSION: FDG PET has a definite role in the assessment of paediatric patients with refractory epilepsy who are being considered for surgery. In the future, analysis of FDG PET data in specific subpopulations of children with refractory epilepsy may lead to novel insights regarding aetiology.

Positron emission tomography with selected mediastinoscopy compared to routine mediastinoscopy offers cost and clinical outcome benefits for pre-operative staging of non-small cell lung cancer.

PURPOSE: (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is an important staging procedure in patients with non-small cell lung cancer (NSCLC). We aimed to demonstrate, through a decision tree model and the incorporation of real costs of each component, that routine FDG-PET imaging as a prelude to curative surgery will reduce requirements for routine mediastinoscopy and overall hospital costs. METHODS: A decision tree model comparing routine whole-body FDG-PET imaging to routine staging mediastinoscopy was used, with baseline variables of sensitivity, specificity and prevalence of non-operable and metastatic disease obtained from institutional data and a literature review. Costings for hospital admissions for mediastinoscopy and thoracotomy of actual patients with NSCLC were determined. The overall and average cost of managing patients was then calculated over a range of FDG-PET costs to derive projected cost savings to the community. RESULTS: The prevalence of histologically proven mediastinal involvement in patients with NSCLC presenting for surgical assessment at our institution is 20%, and the prevalence of distant metastatic disease is 6%. Based on literature review, the pooled sensitivity and specificity of FDG-PET for detection of mediastinal spread are 84% and 89% respectively, and for mediastinoscopy, 81% and 100%. The average cost of mediastinoscopy for NSCLC in our institution is 4,160 AUD, while that of thoracotomy is 15,642 AUD. The cost of an FDG-PET scan is estimated to be 1,500 AUD. Using these figures and the decision tree model, the average cost saving is 2,128 AUDper patient. CONCLUSION: Routine FDG-PET scanning with selective mediastinoscopy will save 2,128 AUD per patient and will potentially reduce inappropriate surgery. These cost savings remain robust over a wide range of disease prevalence and FDG-PET costs.