Comprehensive MRI Brain and Cranial Nerve Imaging: Orbits, IACs, Pituitary, TMJ

What is the primary purpose of routine brain imaging before specialized MRI?

To assess the entire brain before obtaining additional images with reduced FOVs and thinner slices.

What type of coil is best for orbital imaging and specialty brain imaging?

Phased-array head coil.

What are the indications for performing MRI of the orbits?

Change in vision, papilledema, peripheral vision issues, and unilateral proptosis.

What is papilledema?

Optic disc swelling that may be caused by increased intracranial pressure.

What imaging sequences are typically used for MRI orbits?

Thin slice coronal and axial images, often with T2 fsat/T1 sequences.

What is the significance of the optic chiasm in MRI imaging?

It is located just superior to the pituitary gland and is important for visual pathway assessments.

What common pathology is seen in MRI IAC imaging?

Acoustic neuromas or schwannomas, which are usually benign tumors in the inner ear canal.

What are the indications for imaging the internal auditory canals (IAC)?

Vertigo, unilateral sensory hearing loss, tinnitus, facial numbness, and trigeminal neuralgia.

What does the term 'sella turcica' refer to?

The concave component of the sphenoid bone where the pituitary gland sits.

What is the role of the pituitary gland?

It acts as the main endocrine interface between the CNS and the rest of the body, maintaining hormonal function.

What imaging parameters are used for pituitary imaging?

Thin cuts in both sagittal and coronal planes, often requiring contrast for better visualization.

What is a microadenoma?

A tumor of the pituitary gland that is less than 10 mm in size.

What is a macroadenoma?

A tumor of the pituitary gland that is more than 10 mm in size.

What is the purpose of dynamic pituitary imaging?

To assess the timing of contrast enhancement in the pituitary gland due to its rich blood supply.

What does contrast help to assess in pituitary imaging?

It helps in identifying abnormal areas that do not enhance, indicating potential adenomas or other pathologies.

What is the significance of using thin axial cuts in MRI IAC imaging?

They provide better visualization of the 7th and 8th cranial nerves due to small FOV and slice thickness.

What imaging technique is used for visualizing the optic nerves?

Axial MRI scans.

What is the typical alignment for patients during MRI imaging?

The same alignment as routine brain imaging.

What can excessive enhancement of a pituitary tumor indicate?

It may indicate a larger tumor or a different type of tumor that enhances more than normal pituitary tissue.

What is the role of the optic radiations in brain imaging?

They extend into the occipital lobe and are assessed during MRI of the brain.

What is the typical slice thickness for thin coronal images in MRI?

Usually 3 mm or less.

What is the importance of spatial resolution in MRI imaging?

Higher spatial resolution allows for better visualization of smaller structures.

What is the significance of the cerebellopontine angle (CPA) in MRI?

It is a common site for schwannomas and may coincide with IAC imaging.

What does the term 'exophthalmos' refer to?

Protrusion of the eye, often associated with orbital masses.

What is the function of cranial nerve 7 (CN 7)?

It is responsible for facial expressions and some aspects of taste.

What is the function of cranial nerve 8 (CN 8)?

It is responsible for hearing and balance.

What is the function of Cranial Nerve I (Olfactory)?

Carries afferent impulses for the sense of smell.

Where does Cranial Nerve I pass through?

The cribriform plate of the ethmoid bone.

What is the primary function of Cranial Nerve II (Optic)?

Carries afferent impulses for vision.

What structure do the optic nerves converge at?

The optic chiasm.

What are the functions of Cranial Nerve III (Oculomotor)?

Raising the eyelid, directing the eyeball, constricting the iris, and controlling lens shape.

What is the primary role of Cranial Nerve IV (Trochlear)?

Directs the eyeball; it is primarily a motor nerve.

What are the three divisions of Cranial Nerve V (Trigeminal)?

Ophthalmic (V1), maxillary (V2), and mandibular (V3).

What is the primary function of Cranial Nerve VI (Abducens)?

Innervates the lateral rectus muscle; primarily a motor nerve.

What are the motor functions of Cranial Nerve VII (Facial)?

Facial expression and transmittal of autonomic impulses to lacrimal and salivary glands.

What sensory function does Cranial Nerve VII (Facial) serve?

Taste from the anterior two-thirds of the tongue.

What are the two divisions of Cranial Nerve VIII (Vestibulocochlear)?

Cochlear (hearing) and vestibular (balance).

What is the primary function of Cranial Nerve IX (Glossopharyngeal)?

Mixed nerve with motor functions for the tongue and pharynx, and sensory functions for taste.

What is unique about Cranial Nerve X (Vagus)?

It is the only cranial nerve that extends beyond the head and neck.

What is the primary function of Cranial Nerve XI (Accessory)?

Primarily a motor nerve supplying fibers to the larynx, pharynx, soft palate, trapezius, and sternocleidomastoid.

What does Cranial Nerve XII (Hypoglossal) innervate?

Extrinsic and intrinsic muscles of the tongue.

What is the role of the articular disk in the TMJ?

Acts as a cushion between the two bones in the TMJ joint.

What are common indications for TMJ imaging?

Limited mouth opening, headaches, clicking or locking of TMJ joint, earaches, and difficulty chewing.

What type of joint is the TMJ classified as?

A hinge joint that also allows for gliding movement.

What is the purpose of using double angles in TMJ imaging?

To assess the TMJ joint space accurately and visualize articular disc movement.

What is the significance of the TMJ in daily activities?

Required for eating, talking, chewing, and yawning.

What is the function of the ligaments in the TMJ?

Provide stability to the TMJ joint.

What imaging techniques are used for TMJ MRI?

Both open mouth and closed mouth images are taken in T1 and T2 weighted images.

What is the role of the ciliary ganglia in Cranial Nerve III (Oculomotor)?

Contains parasympathetic cell bodies that control iris constriction.

What is the anatomical location of the cranial nerves?

Origination lies around the center of the brain/brain stem.

What is the function of the articular fossa in the TMJ?

It is the joint space of the TMJ.

What is the primary sensory function of Cranial Nerve X (Vagus)?

Taste.

What does the term 'fossa' refer to in TMJ anatomy?

A trench or hollow area in the joint space.