Clinical applications of SPECT with special reference to oncology.

Single photon emission tomography SPECT has been used in nuclear medicine since the early 1960’s when Kuhl and Edwards developed a rectilinear scanning system for use in neuronuclear medicine. Tomography is now used extensi vely for diagnosis by ultrasound, x-ray CT scanning and magnetic resonance imaging. The improvement in quality of the images is due to the enhanced contrast produced by the tomographic technique. Radioisotope emission tomography has special problems which are produced by the Iow infor mation density in the images. However recently several deve lopments have occured which have greatly enhanced the value of SPECT in clinical practice. New radiopharmaceuti cais have been become available which concentrate to relati vely high leveis in the pathology than in the normal surrounding tissues. Examples include mIBG, Tc99m FIM PAO, labelled antibodies and of course bone imaging agents. Radioisotope imaging equipment has improved dramatically with the development of high resolution stable detectors with good uniformity, fast computing and good operator interac tive displays. The result has been a great improvement in the clinical images from tomographic examinations which are available in seconds after the acquisition has been comple ted. However these results can only be obtained with the application of good quality cóntrol and the correct use of filters to match the clinical situation Emission tomography is used for diagnosis and research in most organs of the body. in the brain it is used mainly for the study of perfusion using HM-PAO. Abnormalities due to vascular problems and tumours can be clearly seen. We have documented the patterns of perfusion in brain tumours and the changes in perfusion of brain tumours as radiotherapy and chemothe rapy produces a response 2 In the thyroid gland we have used SPECT to provide data on radiation dosimetry to correlate the clinical effect of radioiodine therapy with the dose delivered ~. We have also demonstrated new anatomical detail of the pyramidal lobe.