New Frontiers in Quantitative Molecular Imaging using PET

Nuclear medicine has a long tradition of incorporating quantitative analysis in its diagnostic and therapeutic procedures. Many of the clinical and research applications of molecular imaging rely on a solid quantitative foundation, which is highly dependent on the performance characteristics of nuclear medicine instrumentation and the accuracy of image correction and reconstruction algorithms. This paper reflects the tremendous increase in interest in standalone (PET) and dual-modality (PET/CT and PET/MR) molecular imaging as both clinical and research imaging modalities in the past decade. New algorithmic developments of image correction and reconstruction techniques are aiming at attaining better image quality and achieving more accurate and automated quantification of physiological parameters of interest in clinical and research settings. Impact of physical degrading factors including attenuation of photons and contribution from photons scattered in the patient and partial volume effect on diagnostic quality and quantitative accuracy of PET data will be discussed. The fundamental concepts of quantitative image analysis techniques as they are applied in diagnostic and therapeutic nuclear medicine using dedicated PET instrumentation and dual-modality imaging devices will be explored. Potential future applications of quantitative molecular imaging are also addressed especially its use prior to therapy for dose distribution modelling and patient-specific 3D dosimetry in treatment planning towards the concept of image-guided ra-