Integrated (18)F-FDG PET/perfusion CT for the monitoring of neoadjuvant chemoradiotherapy in rectal carcinoma: correlation with histopathology

PURPOSE: The aim of this study was to prospectively monitor changes in the flow-metabolic phenotype (ΔFMP) of rectal carcinoma (RC) after neoadjuvant chemoradiotherapy (CRT) and to evaluate whether ΔFMP of RC correlate with histopathological prognostic factors including response to CRT. METHODS: Sixteen patients with RC (12 men, mean age 60.7 ± 12.8 years) underwent integrated (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/perfusion CT (PET/PCT), followed by neoadjuvant CRT and surgery. In 13 patients, PET/PCT was repeated after CRT. Perfusion [blood flow (BF), blood volume (BV), mean transit time (MTT)] and metabolic [maximum and mean standardized uptake values (SUVmax, SUVmean)] parameters as well as the FMP (BF × SUVmax) were determined before and after CRT by two independent readers and correlated to histopathological prognostic factors of RC (microvessel density, necrosis index, regression index, vascular invasion) derived from resected specimens. The diagnostic performance of ΔFMP for prediction of treatment response was determined. RESULTS: FMP significantly decreased after CRT (p  0.05). After CRT, BV and SUVmax correlated positively with the necrosis index (r = 0.67/0.70), SUVmax with the invasion of blood vessels (r = 0.62) and ΔFMP with the regression index (r = 0.88; all p < 0.05). ΔFMP showed high accuracy for prediction of histopathological response to CRT (AUC 0.955, 95 % confidence interval 0.833-1.000, p < 0.01) using a cut-off value of -75 %. CONCLUSION: In RC, ΔFMP derived from integrated (18)F-FDG PET/PCT is useful for monitoring the effects of neoadjuvant CRT and allows prediction of histopathological response to CRT

Lista de recomendações do Exame PET/CT com 18F-FDG em Oncologia: consenso entre a Sociedade Brasileira de Cancerologia e a Sociedade Brasileira de Biologia, Medicina Nuclear e Imagem Molecular Recommendations on the use of 18F-FDG PET/CT in Oncology: consensus between the Brazilian Society of Cancerology and the Brazilian Society of Biology, Nuclear Medicine and Molecular Imaging

Apresentamos uma lista de recomendações sobre a utilização de 18F-FDG PET em oncologia, no diagnóstico, estadiamento e detecção de recorrência ou progressão do câncer. Foi realizada pesquisa para identificar estudos controlados e revisões sistemáticas de literatura composta por estudos retrospectivos e prospectivos. As consequências e o impacto da 18F-FDG PET no manejo de pacientes oncológicos também foram avaliados. A 18F-FDG PET deve ser utilizada como ferramenta adicional aos métodos de imagem convencionais como tomografia computadorizada e ressonância magnética. Resultados positivos que sugiram alteração no manejo clínico devem ser confirmados por exame histopatológico. A 18F-FDG PET deve ser utilizada no manejo clínico apropriado para o diagnóstico de cânceres do sistema respiratório, cabeça e pescoço, sistema digestivo, mama, melanoma, órgão genitais, tireoide, sistema nervoso central, linfoma e tumor primário oculto.<br>The authors present a list of recommendations on the utilization of 18F-FDG PET/CT in oncology for the diagnosis, staging and detection of cancer, as well as in the follow-up of the disease progression and possible recurrence. The recommendations were based on the analysis of controlled studies and a systematic review of the literature including both retrospective and prospective studies regarding the clinical usefulness and the impact of 18F-FDG PET/CT on the management of cancer patients. 18F-FDG PET/CT should be utilized as a supplement to other conventional imaging methods such as computed tomography and magnetic resonance imaging. Positive results suggesting changes in the clinical management should be confirmed by histopathological studies. 18F-FDG PET should be utilized in the diagnosis and appropriate clinical management of cancer involving the respiratory system, head and neck, digestive system, breast, genital organs, thyroid, central nervous system, besides melanomas, lymphomas and occult primary tumors