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Flashcards in hypothalamus pituitary imaging Deck (19):
1

MRI measures what three properties

1. proton density. 2. T1 relaxation rate: tendency to align with magnetic field. 3. T2 relaxation rate: loss of magnetization

2

Use of contrast in MRI

Used to detect leaky capillaries

3

What things show up bright on T1

fat, some proteins, blood products, paramagnetic ions such as iron, gadolinium, manganese and some complexes of Ca.

4

What shows up bright on T2

fluid, gliosis (from increased water content), tumors that have increased water content. Tumors with low cytoplasmic/nuclear ratios have low T2 signal (dark). Other T2 dark substances are old blood, hemosiderin, certain complexes of calcium (bone cortex), air and high concentration protein complexes.

5

compare the brain in T1 vs T2 images

T1: : White matter is brighter than gray matter. Fluid is generally dark. T2: White matter is darker than gray matter, fluid is bright

6

MRI pituitary imaging sequences

1. High resolution Sagittal and Coronal pre and post contrast T1-weighted images. 2. High resolution Coronal T2-weighted images. 3. 1st time studies usually include whole brain (for associated or incidental pathology)

7

Which structures of pituitary show up bright on T1, T2?

Anterior pituitary: Enhances (NoBBB) and low T2. Intermediate/septum: slightly brighter on T2. Posterior: sometimes bright on T1 due to neuropeptides, does not fat saturate

8

Be able to identify the following structures on MRI: adenohypophysis, neurohypophysis, mamillary body, optic chaism, tuber cinerium

T1

9

what are mamillary bodies

these inferior “bumps” mark the posterior floor of the hypothalamus and receive incoming fibers from the fornix.

10

What is the tuber cinerium

lies at the inferior floor of the hypothalamus, posterior to the infundibulum and anterior to the Mamillary bodies. It is one of two common sites of hypothalamic hamartomas

11

Be able to identify the following structures on MRI: infundibulum, Dorsum sella, cingulate gyrus, corpus callosum, fornix, massa intermedia, suprasellar cistern

T1

12

What is the dorsum sella

Posterior Bone of Sella Turcica, can be difficult to differentiate from neurohypophysis.

13

What is fornix

Connects hippocampi with the Mamillary bodies (main output of hippocampal formations)

14

What is the massa intermedia

(AKA intrathalamic adhesion) connects the thalami across midline

15

What is the suprasellar cistern

CSF-filled supraclinoid area above the diaphragma sella

16

Which brain structures enhance in T1 with contrast

Adenohypophysis (adenomas enhance less though), neurohypophysis is same as in non contrast, infundibulum,

17

What is a flow void

Flowing blood often brings non-excited fluid into the field of electromagnetic excitation. It thus has no signal and creates a “flow void”. This occurs in the cavernous sinuses on T1 and T2 images

18

Define pituitary microadenoma

<1cm

19

define macroadenoma

>1cm