محاضره 8.pdf

L8- / MRI OF brain 2024-2023 department of Radiology Alayan university Dr. Raad ajeel/PHD Radiology tech. Introduction: Understanding brain MRI imaging is essential for MRI technologist to perform MRI exams effectively, interpret MRI results accurately, optimize MRI parameters, and keep up-to-date w...

L8- / MRI OF brain 2024-2023 department of Radiology Alayan university Dr. Raad ajeel/PHD Radiology tech. Introduction: Understanding brain MRI imaging is essential for MRI technologist to perform MRI exams effectively, interpret MRI results accurately, optimize MRI parameters, and keep up-to-date with MRI technology. Brain MRI imaging can provide information about the brain's anatomy, detect abnormalities, and measure blood flow and diffusion in the brain. MRI technologist can learn about brain MRI imaging through MRI tech programs, continuing education courses, and on-the-job training Common indications.. -MS - Primary tumour assessment and/or metastatic disease -AIDS (toxoplasmosis) -Infarction (cerebral vascular accident (CVA) versus transient ischaemic attack (TIA)) -Haemorrhage - Hearing loss -Visual disturbances. - Infection.. -Trauma - Unexplained neurological symptoms or deficit -Preoperative planning -Radiation treatment planning -Follow-up (surgical or treatment) Equipment -Head coil (quadrature or multi-coil array) - Immobilization pads and straps -Earplugs/headphones -High-performance gradients for EPI, diffusion and perfusion imaging Patient positioning :The patient lies supine on the examination couch with their head within the head coil. The head is adjusted so that the inter-pupillary line is parallel to the couch and the head is straight. The patient is positioned so that the longitudinal alignment light lies in the midline, and the horizontal alignment light passes through the nasion. Straps and foam pads are used for immobilization. Main MRI sequences of the brain 1-T1-Weighted Axial Imaging: Parameters: Slice thickness: 5-6 mm Use: Provides detailed anatomical information of the brain, helps in detecting tumors, and is often used as a baseline for post-contrast imaging. 2-T2-Weighted Axial Imaging: Parameters: Slice thickness: 5-6 mm Use: Highlights lesions, edema, and cysts. Good for detecting white matter diseases and brain abnormalities. 3-T1-Weighted Coronal Imaging: Parameters: Slice thickness: 5-6 mm for Use: Provides a different perspective of brain anatomy, especially useful assessing the pituitary gland and other coronal structures. 4-Fluid-Attenuated Inversion Recovery (FLAIR) Imaging: Parameters: Slice thickness: 5-6 mm Use: Suppresses CSF signal and enhances lesion visibility, helpful in detecting multiple sclerosis (MS) lesions and vascular abnormalities. 5-Diffusion-Weighted Imaging (DWI): Parameters: Slice thickness: 5-6 mm b-values: Typically. 0 and 1000 sec/mm² Use. Detects areas of restricted diffusion. valuable for diagnosing acute stroke and evaluating tissue damage. 6- Diffusion Tensor Imaging (DTI) Parameters: Slice thickness: 2-3 mm Use: Maps white matter tracts, assesses brain connectivity, and studies conditions like traumatic brain injury and white matter diseases. 7-Susceptibility-Weighted Imaging (SWI): Parameters: Slice thickness: 1-2 mm Use: Detects hemorrhages, microbleeds, and venous abnormalities, useful in cases of head trauma and vascular disorders. 8-Functional MRI (fMRI): Parameters: Typically includes T2*-weighted or BOLD (Blood Oxygen Level Dependent) sequences. Use: Maps brain activity and connectivity during tasks or at rest, used in research and for preoperative planning in certain cases. 9-Magnetic Resonance Spectroscopy (MRS): Parameters: Acquires spectra from specific regions of interest. Use: Measures biochemical information about brain tissue, aids in characterizing brain lesions, tunors, and metabolic disorders. 10- Perfusion MRI (pMRI): Uses dynamic contrast enhancement or arterial spin labeling. Use: Measures blood flow to assess brain perfusion, valuable in diagnosing and monitoring acute stroke, vasculitis, and tumor response to treatment. In Summary, these sequences offer a comprehensive view of the brain's structure, function, and blood flow, allowing for the diagnosis and evaluation of various neurological conditions and diseases. The choice of sequences and parameters may vary depending on the clinical indication and the patient's specific needs. Always consult with a medical professional or radiologist for the most appropriate MRI protocol.