Clinical applications with the HIDAC positron camera

A high density avalanche chamber (HIDAC) positron camera has been used for positron emission tomographic (PET) imaging in three different human studies, including patients presenting with: (I) Thyroid diseases (124 cases); (II) clinically suspected malignant tumours of the pharynx or larynx (ENT) region (23 cases); and (III) clinically suspected primary malignant and metastatic tumours of the liver (9 cases, 19 PET scans). The positron emitting radiopharmaceuticals used for the three studies were Na124I (4.2 d half-life) for the thyroid, 55Co-bleomycin (17.5 half-life) for the ENT-region and 68Ga-colloid (68 min half-life) for the liver. Tomographic imaging was performed: (I) 24 h after oral Na124I administration to the thyroid patients, (II) 18 h after intravenous administration of 55Co-bleomycin to the ENT patients and (III) 20 min following the intravenous injection of 68Ga-colloid to the liver tumour patients. Three different imaging protocols were used with the HIDAC positron camera to perform appropriate tomographic imaging in each patient study. Promising results were obtained in all three studies, particularly in tomographic thyroid imaging, where a significant clinical contribution is made possible for diagnosis and therapy planning by the PET technique. In the other two PET studies encouraging results were obtained for the detection and precise localisation of malignant tumour disease including an estimate of the functional liver volume based on the reticulo-endothelial-system (RES) of the liver, obtained in vivo, and the three-dimensional display of liver PET data using shaded graphics techniques. (orig./HSI)