Apport de l’imagerie hybride TEMP-TDM dans le suivi d’un cancer différencié de la thyroïde

Abstract

In the management of patients with differentiated thyroid cancer (DTC), abnormalities detected on planar whole body scan and 131I-SPECT are difficult to interpret because of a lack of anatomical landmarks and limited specificity. Integrated 131I-SPECT-CT imaging has an additional value for characterization of equivocal tracer uptake seen on planar imaging as well as for precise localization. We illustrate through an observation the incremental diagnostic value of 131I-SPECT-CT images in the diagnosis of a cervical lymph node mimicking a physiological uptake on planar views. A 35-year-old Tunisian female was followed for papillary thyroid carcinoma, for which she underwent total thyroidectomy and iratherapy. Three years after a complete remission, the thyroglobulin (Tg) level on TSH stimulation increased. Diagnostic planar images with 131I did not disclose any obvious pathological foci. Furthermore, we noticed an increased 131I-uptake in the left sub-mandibulary area, which suggested a salivary physiological activity. SPECT-CT of the neck and chest were then performed with a Symbia T camera. Fused images demonstrate that this activity corresponds to a cervical lymph node closely adjacent to sub-mandibulary gland. Management of the patient was then changed. In selected patients with DTC, hybrid imaging should be used as a complementary to planar imaging in terms of diagnostic accuracy, because of superior focus localization and additional anatomic information derived from the CT component. Integrated SPECT-CT is then a useful tool, especially in cases of unclear diagnoses, precising anatomical localization of areas of increased 131I-uptake and distinguishing malignant lesions from normal physiological uptakes. This is particularly important in an oncologic center, as ours, where we don’t yet have a positron emission tomography (PET) camera is not yet available.