Imaging of the Thyroid and Parathyroid Using a Cardiac Cadmium-Zinc-Telluride Camera: Phantom Studies

Cadmium-zinc-telluride (CZT) detectors have recently been introduced to the field of clinical nuclear cardiology. However, the feasibility of using them for organs other than the heart remains unclear. The aim of this study was to evaluate the potential of a cardiac CZT camera to acquire thyroid and parathyroid images. We used custom-made phantoms and the currently available standard protocols for a CZT camera, instead of a sodium-iodine scintillation (NaI) camera. Methods: Thyroid phantoms with or without parathyroid adenomas were made from agar using radiopharmaceuticals (^99mTc or ¹²³I) and imaged using CZT and NaI cameras. Using the CZT camera data, we prepared maximum-intensity-projection (MIP) images and planar-equivalent images. Image counts were compared with those from the NaI camera, and the radioactivity of the phantoms was measured. For parathyroid imaging, 3 different protocols with the NaI camera were tested using MIP images. Results: For thyroid imaging, MIP could provide images as clear as those obtained from the NaI camera. The radioactivity and image counts correlated better for the planar-equivalent images than for the MIP images, especially for ¹²³I. We succeeded in obtaining clear parathyroid adenoma images from MIP images using all 3 protocols. Conclusion: A cardiac CZT camera can effectively perform qualitative and quantitative assessments of the thyroid and parathyroid organs.