MRI of the Brain PDF

MRI of the brain Dr.Hayder Jasim Taher PhD of Medical Imaging Outline of my presentation ✓Anatomical overview. ✓Indications of brain MRI. ✓MRI procedure. ✓Patient position. ✓Scout slice placement. ✓MRI sequences (Routine brain) ...

MRI of the brain Dr.Hayder Jasim Taher PhD of Medical Imaging Outline of my presentation ✓Anatomical overview. ✓Indications of brain MRI. ✓MRI procedure. ✓Patient position. ✓Scout slice placement. ✓MRI sequences (Routine brain)  Anatomical overview Nervous system is a complex network of nerves and cells that carry messages to and from the brain and spinal cord to various parts of the body. It was divided into: - 1- Central nervous system (CNS): - Which include the brain and spinal cord. 2- Peripheral nervous system (PNS): - It consist of the nerves that branch out from the brain and spinal cord. These nerves form the communication network between the CNS and the body parts.  Anatomical overview Brain: - It consists of three main parts: A - Cerebrum: - It is the largest part of the brain; it consists of two hemispheres. The cortex contains mostly nerve cell bodies and appears as grey matter, below the cortex, nerve fibers traveling toward and away from the cortex forming the white matter. B - Cerebellum: - The second largest part of the brain. It located in the posterior cranial fossa. Its outer layer containing a concentration of cell bodies (grey matter) and its deeper layers containing mostly cell processes and supportive cells (white matter). (fig.1) Fig-1- parts of brain  Anatomical overview C- Brain stem: - Which consist of the following parts: - (fig.2) 1-Midbrain: - The bundle of nervous tissue connecting the cerebrum with the cerebellum and spinal cord. 2- Pons: - Located anterior to the cerebellum. The enlarged portion of the brain stem where fibers from the cerebellum join those from the cerebrum and spinal cord. 3- Medulla oblongata: - Form the lower brain stem directly below the pons and contains all the ascending and descending tracts that communicate between the spinal cord and brain.  Anatomical overview Fig-2- parts of brain stem  Anatomical overview MRI brain is a specialist investigation that is used for the assessment of a number of neurological conditions. It is the main method to investigate conditions such as multiple sclerosis and headaches and used to characterize strokes and space-occupying lesions.  Indications of brain MRI Tumors: in comparison with CT, MRI has the advantage of detecting lesions in the posterior fossa, at the edge of calvarium and is superior for lesions near the base of the skull and the pituitary fossa. Hemorrhage-Ischemic stroke: Both these conditions are easily detected by MRI. For example, the detection of thrombosis/stenosis is a very promising application of MR angiography.  Indications of brain MRI Trauma: In comparison with CT, MRI has the advantage of demonstrating the entire extent of the extracerebral collection plus superior evaluation of diffuse axonal injury and sequelae of trauma. Disadvantages include the longer scanning times and the inability to demonstrate the bony cranium. Degenerative Diseases: MRI is extremely effective in diagnosing multiple sclerosis, subcortical arteriosclerotic encephalopathy, gliosis and syrinx.  MRI procedure: Patient position: 1- Patient should be in supine-position. (head first). (Fig.3) 2- Place the patient in the head coil. 3- The patient should be well padded to prevent image degradation or malalignment due to head movement. 4- If the imaging coil has a mirror, ensure the patient is able to see out of the bore to alleviate claustrophobia. (Fig.3) Patient position-head coil  MRI procedure: Scout slice placement: - 1- Sagittal localizer to obtain axial slices: - Alignment: Parallel to a line joining the splenium and genu of the corpus callosum. - Coverage: A- Superior to inferior: Craniocervical junction to vertex. B-Lateral to medial: Temporal lobes on both sides. C-Posterior to anterior: Occipital to frontal lobes. - Note: We can use a coronal localizer to obtain axial slices also.  MRI procedure: 2 - Sagittal localizer to obtain coronal slices: - Alignment: Parallel to the brainstem. - Coverage: A- Superior to inferior: Craniocervical junction to vertex. B-Lateral to medial: Temporal lobes on both sides. C-Posterior to anterior: Occipital to frontal lobes. Note: We can use axial localizer to obtain coronal slices also.  MRI procedure: 3-Axial localizer to obtain sagittal slices: -Alignment: Parallel to the falx (If midline shift is evident, a line of best fit should be used). -Coverage: A- Superior to inferior: Craniocervical junction to vertex. B-Lateral to medial: Temporal lobes on both sides. C-Posterior to anterior: Occipital to frontal lobes. -Note: We can use a coronal localizer to obtain sagittal slices also. MRI sequences (Routine brain):  MRI sequences (Routine brain): Notes: -T1WI provides the most anatomically-relevant images. -Flair images useful for areas of edema or inflammation and used to identify plaques in multiple sclerosis. -DWI was the preferable in case of stroke, abscesses, and cellular tumors since the restricted diffusion was occurs in these pathological conditions.