Читать книгу Essentials of MRI Safety - Donald W. McRobbie - Страница 20

Since its adoption in the late 1980s the scope of MRI’s clinical applications has grown, and continues to grow. Brain, spine, and musculoskeletal imaging were the first major applications.

MRI’s ability to differentiate between grey and white matter in the brain led to its deployment in neuroradiology, particularly for white matter disease and brain tumors. The development of diffusion‐weighted imaging (DWI) gives MRI the ability to detect acute stroke and chronic infarct. Functional MRI (fMRI) is a popular tool in neuroscience research which utilizes the Blood Oxygenation Level Dependent (BOLD) effect to map neural activation. White matter connectivity can be investigated using diffusion tensor imaging (DTI) or high angular diffusion imaging (HARDI) and tractography. In musculoskeletal MRI soft tissue components, muscle, bone marrow, fat, and cartilage are all visible. Whilst tendon, ligament, and cortical bone are inferred by their absence of signal, edema resulting from injury is highly conspicuous.

MRI has a major role in oncology through tumor imaging, often using DWI for diagnosis, staging, and treatment assessment. Applications include breast, bowel, prostate, liver, pancreas, female pelvis, in addition to brain and spine. MR spectroscopy (MRS) provides in‐vivo bio‐chemical information on tumor and tissue metabolism. Through sensitizing the MR signal to flow or by the injection of a gadolinium‐based contrast agent (GBCA) angiographic images can be obtained to investigate vascular disease. The development of rapid GRE sequences has facilitated cardiac MR for heart morphology and function studies. GRE using the in‐phase–out‐of‐phase technique is applied in liver and abdominal imaging of adenoma and cirrhosis, whilst TSE/FSE can indicate cysts, hepatocellular carcinoma and metastases. Single‐shot TSE/FSE is used for MR cholangio–pancreatography (MRCP) in the biliary system. Some of these are illustrated in Figures 1.8 and 1.10.