Possibilities of single photon emission tomography in the diagnosis of bone metastases in patients with disseminated medullary thyroid carcinoma (case report)

Abstract

The study objective: using a clinical example to demonstrate possibilities of single photon emission computerized tomography (SPECT) in combination with computed tomography (CT) in identifying latent bone metastases, taking into account the dynamics growth of serum basal calcitonin.Materials and methods. Patient S., 60 years old, visited N.N. Blokhin National Medical Research Center of Oncology for consultation on multiple lung metastases of cancer of unknown primary.Results. Taking into account basal calcitonin level, immunohistochemistry, ultrasound investigation andfine-needle aspiration biopsy of the node in the right thyroid lobe a diagnose of medullary thyroid cancer was made. CT revealed multiple metastases in both lungs. Specialist erformed thyroidectomy with central lymphadenectomy and facial neck dissection on both sides. During next four months basal calcitonin level increased twice. Control contrast CT lung screening showed the growth of previously identified metastases and the appearance of multiple new ones. Bone scan showed focuses of increased radio-pharmaceutical accumulation in the area of 7h left rib, left iliac wing, in the left bones of cranial vault, in C7, Th6, Th9, ThI2 vertebrae and right foot bones. Additional examination using SPECT/CT (from the skull base to the hip joints) revealed metastases in corpuses of Th9, ThI2 vertebrae and the left iliac wing, and suspicion for metastasis in 7h left rib. Magnetic resonance imaging (MRI) confirmed metastasis in Th9, ThI2, L3 vertebral bodies and in the left iliac wing.Conclusion. Conclusion. In this clinical example, SPECT/CT allowed to correctly detect metastases in both Th9 and ThI2 vertebrae while bone scan was questionable, and MRI showed an additional damage of L3 vertebra. Changes in the 7h left rib could not be verified using CT, although this changes may be an emerging metastasis. Obviously, extensive use of radiation methods does not guarantee complete identification of all pathological focuses, it therefore allows assessing the prevalence of the pathological process. It is crucially important to control calcitonin level in these patients, since its rapid growth allowed suspecting additional distant metastases.

Keywords

• medullary thyroid carcinoma
• calcitonin
• bone metastases
• single photon emission computed tomography