RC 406 - Molecular imaging: what can we quantify?
1. To learn about functional MRI (fMRI, DCE-MRI), diffusion tensor imaging (DTI) and diffusion-weighted imaging (DWI).
2. To understand the application of these techniques in the study of the healthy and diseased.
3. To learn about quantification using MR.
Functional MR imaging (fMRI) and diffusion tensor imaging (DTI) are used extensively in the research arena to study an infinite number of questions regarding the brain’s function and structure under normal conditions, as well as with neurological and psychiatric disease. The clinical use of these techniques, however, is by comparison fairly limited. The current main indication is the presurgical assessment of the relationship between the brain tissue to be resected and functionally eloquent brain tissue. In the context of brain tumour surgery, the aim is maximum tumour resection, while at the same time avoiding functional deficit. With tumour localisation in or near presumed eloquent brain areas, such as the motor or language areas, additional fMRI and DTI may be advantageous to guide the neurosurgical approach, shorten surgery duration and obtain prognostic information prior to surgery. fMRI is used to localise eloquent cortex, which is particularly useful when normal anatomy is obscured by tumour mass effect or in cases of cortical plasticity. With DTI the anatomy and involvement of white matter tracts may be evaluated. Inadvertent transection of white matter tracts during surgery leads to severe neurological deficit. DTI-tractography offers attractive visualisation of the major white matter tracts such as the corticospinal tract and the arcuate fasciculus, and offers valuable preoperative information on their relationships with the brain tumour to be resected. As well as providing such anatomical information, colour-coded eigenvector maps obtained with DTI can be used to categorise involvement of the white matter tracts by brain tumour.
1. To understand the fundamentals of PET physics relevant to MR/PET imaging.
2. To appreciate the advantages of MR/PET and its complementary role in diagnostic oncology.
3. To learn about the benefits and challenges of quantification in PET.
PET is a non-invasive imaging technique that provides reproducible and fully quantitative information on preselected metabolic/signalling pathways. PET is highly sensitive, thus, requiring only small amounts of biomarkers to be used for visualization and quantification purposes. Today, clinical PET imaging systems are offered almost exclusively in combination with CT and MR systems. Advantages of these imaging combinations are manifold and include, mainly for PET/CT, a marked reduction in total acquisition time, and improved spatio-temporal alignment of the complementary image information. Advancing PET-imaging technology into combined PET-based imaging technology included methodological input and technical innovation. We will highlight the most important advances of PET instrumentation that help increase volume sensitivity, improve spatial resolution and overall image quality. PET imaging in the context of combined PET/MRI was made possible only through the introduction of completely revised PET detectors that can operate in high-strength magnetic fields. Overall, increased volume sensitivity helps reduce the amount of radiotracer injected into patients or shorten the emission scan time, in combination with increased signal-to-noise in the emission images it helps increase sensitivity and reader accuracy of PET images. Lastly, advances in image reconstruction have brought the level of PET, and the appearance of the PET images, closer to the common understanding of radiologically useful images. Following this presentation, the audience will 1. learn about the benefits and challenges of quantification in PET, 2. understand the fundamentals of PET physics relevant to PET/MR imaging and 3. appreciate the advantages of PET/MR and its complementary role in diagnostic oncology.
1. To become familiar with the role of hybrid imaging in clinical oncology.
2. To learn about quantification in oncology: its benefits and limitations.
3. To understand hybrid imaging applications in relationship to disease presentations.
Over the past 15 years, hybrid imaging, in terms of PET/CT, has become an essential part of clinical oncologic imaging. It has been well demonstrated to provide fast, high-quality, quantifiable imaging for numerous application fields, including whole-body staging and restaging in cancer patients, therapy monitoring and for radiation therapy planning. The combined assessment of morphological and metabolic features of tumours has not only been shown to add valuable non-invasive information concerning tumours, but also improve the diagnostic competence to higher levels than sole morphological cross-sectional imaging. The successful introduction of simultaneous PET/MRI into clinical imaging, in terms of the interchange of the CT component for anatomical correlation to MRI, has leveraged hybrid imaging onto utterly new and emerging platforms of tumour assessment. The application of multi-parametric PET/MRI imaging, comprising high-resolution morphological imaging as well as functional parameters such as diffusion-weighted imaging, perfusion parametrics and tumour metabolism, facilitates an improved understanding of tumour biology as well as prognostic factors. Furthermore, it enables improved therapy monitoring to better differentiate between potential responders and non-responders to chemo- and/or radiation therapy.