Brain stem and Cerebellar Imaging Prepared by Dr. Sarah Kamal Lecturer of Radio-diagnosis . Neurophychiatry block – Course Name and No. 6/29/2019

Learning objectives Students at the end of the lecture will be able to: • Identify radiological anatomy of brain stem and cerebellum. • Compare CT and MRI imaging of brain stem and cerebellum. • Recognize the imaging findings in common diseases involving brain stem and cerebellum. اسم ورقم المقرر – Course Name and No. 6/29/2019

There are three major divisions of the brain, with each division having specific functions. The major divisions of the brain are the forebrain (prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon). Prosencephalon : Forebrain - Diencephalon thalamus, hypothalamus - Telencephalon cerebrum 2. Mesencephalon – Midbrain 3. Rhombencephalon : Hindbrain - Metencephalon pons and cerebellum - Myelencephalon medulla oblongata • MRI brain sag T1WI 1-midbrain 2-pons 3-medulla oblongata اسم ورقم المقرر – Course Name and No. 6/29/2019

Brainstem: Three parts from superior to inferior: 1- midbrain 2- pons 3- medulla oblongata • Connects cerebral hemisphere with spinal cord اسم ورقم المقرر – Course Name and No. 6/29/2019

اسم ورقم المقرر – Course Name and No. 6/29/2019

Midbrain: Radiological Features: • At the level of circle of Willis Anteriorly two cerebral peduncles separated by interpeduncular fossa • Posteriorly four rounded prominences (superior and inferior colliculi) اسم ورقم المقرر – Course Name and No. 6/29/2019

MRI of the brain, T1WI sagittal view. 1, Lateral ventricle. 2, Caudate nucleus.  3, Thalamus. 4, Midbrain.  5, Oculomotor nerve (III).  6, Pons. MRI of the brain, T1-weighted axial view. 1, Substantia nigra.  2, Tegmentum.  3, Tectum.  4, Cerebral peduncle اسم ورقم المقرر – Course Name and No. 6/29/2019

Pons: Radiological Features: • The bulbous anterior part consists mainly of fibers continuous on each side with middle cerebellar peduncle • Basilar artery lies in groove anteriorly (black color) • Posterior surface of the pons forms the upper part of the floor of the 4th ventricle. • Bony anterior relation: clivus centrally and petrous temporal bones laterally At the leve of petrous bone. Basilar artery in white color indicates infarction of the artery. اسم ورقم المقرر – Course Name and No. 6/29/2019

3- middle cerebellar peduncle 2 3 1 1 P- pons 1- 4th ventricle 2- basilar artery 3- middle cerebellar peduncle اسم ورقم المقرر – Course Name and No. 6/29/2019

Medulla oblongata: Radiological Features: • MRI imaging of the medulla gives superior images to CT due to lack of bony artifact • The ventral median fissure is seen anteriorly with the pyramid laterally • The 4th ventricle is seen posteriorly اسم ورقم المقرر – Course Name and No. 6/29/2019

Cerebellum: Radiological Anatomy: • Cerebellum is connected to the brainstem by three pairs of Cerebellar Peduncles: Superior..........connected to the midbrain Middle.............connected to the pons inferior..............connected to medulla oblongata • The two cerebellar hemisphere connected in midline by Vermis. • Flocculus is a small ventral portion of the hemisphere • Tonsils are the most inferior part of the hemispheres that lie close to the midline • The superior vermis can be seen between occipital lobes on section through the thalamus. اسم ورقم المقرر – Course Name and No. 6/29/2019

Radiological Features: • On axial Ct & MRI the cerebellum is separated from the pons by the 4th ventricle and connected to the pons on each side by middle cerebellar peduncle, it is bounded anteriorly by petrous temporal bone • On higher slices it is separated from temporal and occipital lobes antero-laterally by tentorial margins, tentorium can be seen on contrast enhanced studies owing to the contained superior petrosal sinus. اسم ورقم المقرر – Course Name and No. 6/29/2019

اسم ورقم المقرر – Course Name and No. 6/29/2019

vermis tonsil flocculus اسم ورقم المقرر – Course Name and No. 6/29/2019

1-Acute infarction due to basilar artery thrombosis Common diseases of brainstem & cerebellum: 1-Acute infarction due to basilar artery thrombosis Axial ct brain showing Hyper dense basilar artery denoting basilar artery thrombosis اسم ورقم المقرر – Course Name and No. 6/29/2019

Acute bilateral pontine infarction (arrow) as a result of acute basilar occlusion shown on diffusion weighted MRI Axial computed tomography scan showing bright (hyperdense) region (arrow) consistent with an acute basilar thrombus اسم ورقم المقرر – Course Name and No. 6/29/2019

2-Medulloblastoma (common in children) Mass in the 4th ventricle and the midline of cerebellum اسم ورقم المقرر – Course Name and No. 6/29/2019

3-Ependymoma Mass with areas of calcification in the 4th ventricle extending through foramen magnum Sagital MRI T1WI contrast Axial MRI T1WI contrast Coronal MRI T1WI contrast اسم ورقم المقرر – Course Name and No. 6/29/2019

4-Hemangioblastoma Mass in the cerebellar hemisphere compressing the 4th ventricle and tonsils through the foramen magnum Sagital MRI T1WI Axial MRI T2WI Coronal MRI T1WI contrast اسم ورقم المقرر – Course Name and No. 6/29/2019

5-Cavernous angioma Sagital MRI brain T1WI showing a mass with mixed intensities from hyper to hypo in the caudal pons suggesting cavernous angioma اسم ورقم المقرر – Course Name and No. 6/29/2019

3-Ependymoma 5-Cavernous angioma Mass in caudal pons 2-Medulloblastoma Mass in the 4th ventricle(child) and the midline of cerebellum 3-Ependymoma Mass with calcification in the 4th ventricle extending through foramen magnum 4-Hemangioblastoma Mass in the cerebellar hemisphere compressing the 4th ventricle and tonsils through the foramen magnum 5-Cavernous angioma Mass in caudal pons اسم ورقم المقرر – Course Name and No. 6/29/2019

6-Cerebellar tuberculosis Axial MRI T1 with contrast well defined semi oval mass with outer enhancement on contrast administration. Diagnosis: Tuberculous mass in the left cerebellar hemisphere) Axial MRI T2WI اسم ورقم المقرر – Course Name and No. 6/29/2019

7-Dandy-Walker malformation: Rare congenital malformation that involves the cerebellum and fourth ventricle. Dandy-Walker malformation is characterized by 1-agenesis or hypoplasia of the cerebellar vermis 2- cystic dilatation of the fourth ventricle 3- enlargement of the posterior fossa. MRI sagittal T1WI Showing:1- large posterior fossa cyst ,2-The hypoplastic vermis is everted over the posterior fossa cyst (long arrow). 3-The cerebellar hemispheres and brainstem (b) are hypoplastic. اسم ورقم المقرر – Course Name and No. 6/29/2019

Axial T2WI MRI Brain scan that shows 1-hydrocephalus, a large cerebrospinal fluid cyst in the posterior fossa,2- thinned occipital bone (arrows), 3- hypoplastic cerebellar hemispheres with a winged appearance (c). اسم ورقم المقرر – Course Name and No. 6/29/2019

Thank you اسم ورقم المقرر – Course Name and No. 6/29/2019