A brain metastasis, with no uptake of 99mTc-ECD, secondary to Hurtle cell carcinoma of the thyroid.

: Visualization of cerebral perfusion with Single Photon Emission Computed Tomography (SPET) needs lipophil radiotracers which are able to cross the intact blood-brain-barrier (BBB); moreover local uptake must reflect regional cerebral blood flow. In the last decade many radiopharmaceuticals have been suggested and employed for this purpose. Recently a new molecule has been synthesized: technetium-99m-labeled ethyl cysteinate dimer (99mTc-ECD). Commonly, SPET of the brain with perfusion tracers is performed to identify ischemic regions. We describe a patient with a bulky cerebral metastasis, secondary to Hurthle cell carcinoma of the thyroid, which concentrated radioiodine. Brain metastases secondary to differentiated carcinoma of the thyroid are very rare and when treated with 131-I may provoke serious neurological problems. Therefore we decided to perform a brain SPET with 99mTc-ECD to exclude regional perfusion defects and deafferentation phenomena. Brain CT showed only the large metastasis. SPET images, reconstructed according to standard tomographic planes of the head: transverse, coronal and sagittal revealed no uptake of 99mTc-ECD within the metastasis and no regional perfusion defects related to compression phenomena or deafferentation. 99mTc-ECD has never been used to image cerebral neoplasm of whatever origin.