Hypothalamic and Pituitary Imaging

Question 1

Basics of MRI

Answer 1

a. Images three properties of protons in magnetic fields:
1. T1 relaxation rate: tendency of protons to align with the magnetic field
2. T2 relaxation rate: loss of magnetization
3. Proton Density

b. No ionizing radiation for MRI—> electromagnetic fields in radiofrequency range
c. Contrast agent detects “leaky capillaries”
d. Imaging in any plane.

Question 2

MRI Pituitary Imaging Sequences

Answer 2

MRI (CT only if contraindication)–> MRI is Gold standard for Pituitary gland viewing

a. High resolution Sagittal and Coronal pre and post contrast T1-weighted images
b. High resolution Coronal T2-weighted images
c. 1st time studies usually include whole brain (for associated or incidental pathology)

Question 3

Pituitary Gland

Answer 3

1. Anterior Pituitary Gland:
   i. Enhances (no BBB), Low T2 signal
   ii. Secretes: Prolactin, GH, ACTH, LH, FSH, TSH
2. Intermediate (Septum)
   i. Usually slightly brighter on T2
3. Posterior Pituitary Gland
   i. Sometimes bright on T1, does not fat saturate
   ii. Secretes: Oxytocin, Vasopressin

Question 4

Basic Structures

Answer 4

What we view with the MRI

a. Adenohypophysis (anterior pituitary)
1. Outside cell predominance: GH and PRL
2. Inside cells: TSH and ACTH

b. Neurohypophysis (posterior pituitary)
c. Pituitary Septum
d. Tuber Cinereum
e. Infundibulum

f. Mammillary bodies
g. Third ventricle
h. Sella turcica
dorsum sella
clinoid processes: anterior and posterior
tuberculum sella
i. Suprasellar cistern

Question 5

Practice on powerpoint

Answer 5

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