MRI - Lecture 4

Question 1

What is the main goal of mapping the human subcortex using MRI?

Answer 1

To improve understanding of subcortical structures, study interindividual variations, and aid in clinical applications.

Question 2

Which MRI technique is frequently used to study the subcortex in vivo at ultra-high resolution?

Answer 2

7 Tesla (7T) MRI.

Question 3

What percentage of subcortical structures is typically overlooked in MRI studies?

Answer 3

93% of subcortical structures are often overlooked or poorly resolved in standard MRI studies.

Question 4

Name two common challenges in MRI studies of the subcortex.

Answer 4

Limited anatomical detail and movement artifacts during scans.

Question 5

What is the Federative Community on Anatomical Terminology’s role in subcortical research?

Answer 5

It provides standardized anatomical terms, aiding in clear communication and mapping of subcortical structures.

Question 6

Describe the purpose of the Amsterdam Ultra-high field adult lifespan database (AHEAD).

Answer 6

AHEAD collects 7T MRI data across the adult lifespan to study changes in brain structure, covering ages 18-80.

Question 7

What are some MRI contrasts available from a single 7T MRI acquisition in subcortical studies?

Answer 7

T1/R1, T2/R2, QSM, and INV2 contrasts.

Question 8

What is MP2RAGE-ME, and how is it used in subcortex MRI studies?

Answer 8

MP2RAGE-ME is a whole-brain imaging protocol providing high-resolution MRI data for precise subcortical analysis.

Question 9

Why are manual delineations important in MRI studies of the subcortex?

Answer 9

They provide high precision by involving multiple raters to identify over 20 subcortical structures, capturing fine details.

Question 10

What is the significance of using probabilistic atlases of the basal ganglia?

Answer 10

Probabilistic atlases improve structural mapping accuracy and capture interindividual variations in the subcortex.

Question 11

Why are post-mortem studies of the subthalamic nucleus (STN) valuable?

Answer 11

They offer excellent anatomical detail without movement artifacts, allowing precise examination of internal STN structure.

Question 12

Name two advantages and two disadvantages of post-mortem subcortical studies.

Answer 12

Advantages: Excellent anatomical detail, combination with microscopy.
Disadvantages: Limited samples, altered MRI characteristics from formalin fixation.

Question 13

What are the three functional subdivisions of the STN?

Answer 13

Motor, associative, and limbic subdivisions.

Question 14

How is the STN clinically significant for neurological treatment?

Answer 14

It is a target for deep brain stimulation (DBS) to manage symptoms in conditions like Parkinson’s disease.

Question 15

What is the goal of 3D immunohistochemical reconstruction in subcortex studies?

Answer 15

To visualize and analyze specific neuronal markers, aiding in understanding STN organization and functional segregation.

Question 16

What types of proteins are used in immunocytochemistry to study subcortical tissue?

Answer 16

Calcium-binding proteins like parvalbumin, calbindin, and calretinin.

Question 17

What is the BigBrain project’s main contribution to subcortical research?

Answer 17

It provides ultra-high-resolution 3D brain data, aiding in detailed anatomical studies of the cortex and subcortex.

Question 18

What distinguishes the in-situ whole-brain MRI approach used in subcortical research?

Answer 18

It involves scanning intact brains with minimal distortion, resembling in vivo imaging as closely as possible.

Question 19

How are tissues processed in whole-brain post-mortem studies for high-resolution analysis?

Answer 19

Tissues are cut into 200-micrometer slices, processed for MRI and histological staining, and reconstructed into a 3D model.

Question 20

Why is co-registration of histological sections with MRI data important in subcortical studies?

Answer 20

Co-registration allows for combining structural MRI with cellular-level data, enhancing spatial accuracy in mapping brain microstructures.

Question 21

Which stains are commonly used in histology to highlight specific subcortical features?

Answer 21

Myelin stains for myeloarchitecture, Nissl for cytoarchitecture, and hematoxylin-eosin for pathology.

Question 22

How does the probabilistic atlas of the subcortex support research on brain structure variability?

Answer 22

It incorporates interindividual variations, including potential age and sex-related differences in the subcortical region.

Question 23

What is pseudofluorescence, and how is it applied in subcortex MRI studies?

Answer 23

Pseudofluorescence is an artificial contrast applied to highlight specific structures, improving visual clarity in MRI images.

Question 24

What future improvements are expected from the combined approach of in vivo and post-mortem subcortex mapping?

Answer 24

Enhanced MRI atlases, better understanding of interindividual differences, and resolution of subcortical structural controversies.