Brain MRI Techniques and Anatomy

MRI of the Brain (12 & 13)

• Understanding brain MRI imaging is critical for MRI technologists to perform effective exams, accurately interpret results, optimize parameters, and stay current with technology.
• Brain MRI can provide information on brain anatomy, detect abnormalities, and measure blood flow and diffusion.
• MRI technologists can enhance their knowledge through dedicated programs, continuing education, and on-the-job training.

Anatomical Overview

• The 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 is divided into the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), comprising nerves branching out from the brain and spinal cord to connect the CNS to the rest of the body.
• The brain is composed of three primary sections:
  • Cerebrum: The largest part, consisting of two hemispheres, with a cortex of nerve cell bodies (gray matter) and underlying nerve fibers (white matter).
  • Cerebellum: The second largest region, located in the posterior cranial fossa, containing a concentration of cell bodies (gray matter) and nerve fiber tracts (white matter).
  • Brainstem: Composed of the midbrain, pons, and medulla oblongata, connecting the cerebrum to the cerebellum and spinal cord; it also contains ascending and descending tracts for communication between the brain and spinal cord.

MRI Brain - Indications

• Tumors: MRI is superior to CT in detecting lesions in the posterior fossa and near the skull base, and for lesions near the pituitary fossa.
• Hemorrhage/Ischemic Stroke: Both readily detectable by MRI, particularly useful for identifying thrombosis or stenosis.
• Trauma: MRI provides a comprehensive view of extracerebral collections and diffuse axonal injury, superior to CT in certain cases, though CT is often faster.
• Degenerative Diseases: MRI is proficient in diagnosing conditions such as multiple sclerosis (MS), subcortical arteriosclerotic encephalopathy (SAE), gliosis, and syrinx.

MRI Procedure - Patient Position

• Patients should be positioned in the supine position (head first).
• The patient should be well-padded to prevent image degradation or movement-related artifacts.
• Ensure the patient can see out of the imaging bore if a mirror is present, to alleviate claustrophobia.

MRI of the Orbit and Sella Turcica (14)

• MRI protocols for orbits and the sella turcica region are used to assess anatomy and pathology of the eye, pituitary fossa, and surrounding structures.
• Indications of orbit MRI: Retro-orbital lesions, optic disc abnormalities, eye infections (e.g., orbital cellulitis), intra-ocular lesions, and retinoblastoma (eye cancer).

MRI of the Cervical Spine (15)

• Cervical spine MRI is vital for assessing anatomy, detecting abnormalities, and ensuring patient safety, collaborating with other medical professionals.
• Indications: Degenerative disc disease, disc herniation, spinal canal stenosis, spinal trauma, suspected fractures, spinal tumors, inflammation, multiple sclerosis or inflammatory arthritis, spinal infections (e.g., vertebral osteomyelitis), spinal vascular malformations, and congenital spinal malformations.

MRI of the Thoracic and Lumbar Spine (16)

• MRI of the dorsal and lumbar spine is a common procedure, particularly when lower back pain or injury is suspected.
• Thoracic spine: The anatomical region between the cervical and lumbar spine, with 12 vertebrae.
  • Vertebral bodies: Medium-sized, heart-shaped.
  • Vertebral canals: Medium-sized and round.
  • Transverse processes: Prominent with costal facets.
  • Spinous processes: Long and angulating downwards.
• Lumbar spine: The lower part of the back, comprising 5 vertebrae.
  • Lumbar spine shape: Five vertebrae which curves anteriorly.

MRI of the Neck (17)

• Computed tomography (CT) is often the preferred method for imaging this region. MRI is useful in assessing disease spread to the tongue and throat cartilages.
• Anatomical structures in the neck include multiple bony structures, cartilages, blood vessels and muscles.
• Indications of neck MRI: Carcinoma of the larynx/hypopharynx, benign neck lesions, and branchial cleft cysts.

MRI of the Chest (18)

• MRI of the chest is less commonly used compared to CT.
• MRI of the chest can be beneficial for situations where radiation exposure needs to be minimized, or when specific soft tissue characterization is required to aid in diagnosis.
• Common Indications: Mediastinal masses, neurogenic lesions, differentiation between lymph nodes and vascular anomalies, and thoracic aortic aneurysms.

MRI of the Abdomen (19-20)

• Abdomen MRI is essential for accurate examinations, result interpretation, patient safety, and collaborating with other healthcare professionals.
• Anatomical structures in the abdomen: Liver (four lobes), gallbladder, common bile ducts, and kidneys along with suprarenal glands.
• Common Indications: Liver lesions (primary vs. metastatic, benign vs. malignant), hepatocellular carcinoma, hemangiomas, hydatid cysts, diffuse liver disease, biliary obstruction.

This quiz covers essential concepts of MRI imaging of the brain, focusing on the role of MRI technologists in performing effective exams and interpreting results. It also provides an anatomical overview of the nervous system, emphasizing the structures of the brain. Enhance your understanding of brain MRI and its applications in medical imaging.