Precise Localization of Occult Gastrointestinal Hemorrhage Using Dynamic SPECT/CT.

Active but intermittent gastrointestinal (GI) bleeding can be readily detected with dynamic planar scintigraphic imaging. This is a case of a 48-year-old woman who presented from an outside institution with active GI bleeding on 99mTc-labeled RBC (99mTc-RBC) scintigraphy, but the upper and lower GI evaluations failed to subsequently localize the site of persistent bleeding. Repeat 99mTc-RBC planar scintigraphy identified a focus of active extravasation in the right lower quadrant of the abdomen. Dynamic SPECT/CT imaging was immediately performed and further identified the ileocecal valve region as the precise site of active extravasation, which was confirmed at surgery.

PET imaging in differentiated thyroid cancer: where does it fit and how do we use it?

Positron emission tomography (PET) is a rapidly evolving imaging modality that has gained widespread acceptance in oncology, with several radionuclides applicable to thyroid cancer. Thyroid cancer patients have been studied most commonly using 18F-Fluorodeoxyglucose (FDG)-PET, with perhaps the greatest utility being the potential localization of tumor in differentiated thyroid cancer (DTC) patients who are radioiodine whole body scan (WBS) negative and thyroglobulin (Tg) positive. Also of value is the identification of patients unlikely to benefit from additional 131I therapy and identification of patients at highest risk of disease-specific mortality, which may prompt more aggressive therapy or enrollment in clinical trials. Emerging data suggest that PET/CT fusion studies provide increased accuracy and modify the treatment plan in a significant number of DTC cases when compared to PET images alone. However, studies documenting improvements in survival and tumor recurrence attributable to FDG-PET imaging in thyroid cancer patients are lacking. Specific case examples of thyroid cancer patients who appear to have benefited from FDG-PET imaging do exist, while less data are available in the setting of anaplastic or medullary thyroid carcinoma. This article reviews the utility and limitations of FDG-PET in DTC management, and offers practical recommendations.

PET imaging in differentiated thyroid cancer: where does it fit and how do we use it?

Positron emission tomography (PET) is a rapidly evolving imaging modality that has gained widespread acceptance in oncology, with several radionuclides applicable to thyroid cancer. Thyroid cancer patients have been studied most commonly using 18F-Fluorodeoxyglucose (FDG)-PET, with perhaps the greatest utility being the potential localization of tumor in differentiated thyroid cancer (DTC) patients who are radioiodine whole body scan (WBS) negative and thyroglobulin (Tg) positive. Also of value is the identification of patients unlikely to benefit from additional 131I therapy and identification of patients at highest risk of disease-specific mortality, which may prompt more aggressive therapy or enrollment in clinical trials. Emerging data suggest that PET/CT fusion studies provide increased accuracy and modify the treatment plan in a significant number of DTC cases when compared to PET images alone. However, studies documenting improvements in survival and tumor recurrence attributable to FDG-PET imaging in thyroid cancer patients are lacking. Specific case examples of thyroid cancer patients who appear to have benefited from FDG-PET imaging do exist, while less data are available in the setting of anaplastic or medullary thyroid carcinoma. This article reviews the utility and limitations of FDG-PET in DTC management, and offers practical recommendations.

Positron emission tomography (PET) é uma modalidade de imagem que vem evoluindo rapidamente e tem ganho ampla aceitação na oncologia em geral e no câncer da tiróide em particular, graças a uma série de radionuclídeos. Pacientes com doenças da tiróide têm sido estudados principalmente com 18F-Fluorodeoxiglicose (FDG)-PET, cuja maior utilidade talvez seja a de poder localizar tumor em pacientes negativos na pesquisa de corpo inteiro e com tireoglobulina positiva. Também é útil na identificação de pacientes que não devem se beneficiar de terapia adicional com 131I e de pacientes de alto risco que podem se beneficiar de terapias mais agressivas ou testes clínicos com drogas alvo-dirigidas. Dados recentes sugerem que a fusão PET/CT aumenta a acurácia e modifica o plano terapêutico de um número significativo de casos de CDT comparada com as imagens de PET apenas. Entretanto, ainda não existem estudos que documentem melhora na sobrevida e na recorrência decorrentes da imagem por FDG-PET em pacientes com câncer da tiróide. Existem exemplos específicos de casos de CDT que aparentemente se beneficiaram do FDG-PET, mas há menos dados relativos ao carcinoma anaplásico ou ao medular. Este artigo revê a utilidade e as limitações do FDG-PET no tratamento do CDT e oferece recomendações práticas.