RC 114 - MRI technology and techniques
1. To understand the technical challenges associated with spinal cord imaging.
2. To learn about new structural and quantitative spinal cord acquisition and analysis protocols.
3. To discuss some of the clinical applications in neurological disease.
In this presentation I would be discussing new developments in acquisition and analysis protocols for spinal cord imaging using a clinical 3T MR system, which are suitable for use in a number of neurological diseases, such as multiple sclerosis (MS), spinal cord injury (SCI), amyotrophic lateral sclerosis (ALS), neuromyelitis optica (NMO) and multiple system atrophy (MSA). In terms of acquisition, protocols which allow depiction of grey matter (GM) and white matter (WM) within the cord will be presented along with examples on how these may facilitate further tissue-specific (i.e. GM/WM) quantitative investigations such as the estimation of tissue volume, diffusion tensor imaging (DTI) metrics and magnetisation transfer ratio (MTR). In terms of analysis methods, recent advances in semi- and fully-automated image segmentation will be presented and discussed.
1. To learn about b1-related problems in clinical MRI.
2. To understand RF-related heating and current efforts to improve the situation.
3. To discuss how to avoid RF-burns in clinical practice.
Magnetic resonance is a frequently used diagnostic tool and considered a fairly safe modality. It is well known that MR is not only exclusively used for diagnostic purposes but also used in interventional care, research and functional studies of various kinds. Clinical demands for faster examinations and higher resolution, and in combination with advanced research has resulted in a development toward stronger magnetic fields and a more powerful and complex technology. This with the consequence that clinical MR of today uses higher frequencies and increased energy deposition in patients and volunteers. There are several known risks in MR and the radiofrequency (rf)-induced heating problem in patients has increased significantly parallel to the fast technological development. Several efforts are made to improve the situation since MR-related rf-burns occur more and more frequent in clinical practice. The rf-heating problem is relatively difficult to predict and may even cause various degrees of burns during regular clinical MR scanning. Improved knowledge and better understanding of this hazard is necessary to minimize risks and avoid unnecessary damage. Heat-related accidents (rf) can be reduced and the situation considerably improved by careful patient preparations and good safety routines prior to MR examinations.
1. To appreciate the role of diffusion imaging in oncology imaging.
2. To discuss the responsibility of radiographers in the application of DWI.
3. To discuss the clinical application of diffusion imaging in MR enterography and paediatric imaging.
Diffusion-weighted magnetic resonance imaging (DWI) derives its image contrast from differences in the motion of water molecules between tissues. Such imaging can be performed very quickly without the need for exogenous contrast medium administration. A series of technological advances have made it feasible to translate DWI measurements to extra-cranial sites, such as the abdomen and pelvis. The application of DWI in oncology has been widely explored. DWI for tumour detection has been shown for a variety of tumour types in adult and paediatric oncology. Used together with other MR imaging techniques, DWI can aid tumour characterization and in distinguishing tumour from non-tumour tissues. DWI is usually performed using an echo-planar imaging technique, in breath-hold, free-breathing or with the use of respiratory and/or cardiac gating. Meticulous attention to technique is important to ensure high-quality images can be consistently obtained. This is one of the key competence of MR radiographers. There is now considerable interest in using DWI for the monitoring of treatment response. Several studies have already shown that the apparent diffusion coefficient (ADC) of tumour in response to successful chemotherapy, radiotherapy and other minimally invasive interventional procedures. Diffusion-weighted MRI is being increasingly used in paediatric body imaging. Its role is still emerging. It holds great promise in the assessment of therapy response in body tumours, with ADC value as a potential biomarker. Body DWI is a technique that can be quickly performed on clinical MR systems, and can be incorporated into existing clinical protocols.