This technique is performed for monitoring the patient and studying the progression of the disease. It comprises different techniques to image the function and structure of the brain.

 

Techniques of neuroimaging:

 

• Structural imaging shows brain volume and cell loss. This technique is more sensitive than functional imaging to early changes in HD patients.

• Functional imaging shows brain performance and cell dysfunction.

 

Brain structure neuroimaging shows basal ganglia size. Injuries in basal ganglia are related to disease duration, severity of movement disturbances, range of dementia, longer CAG expansions and cognitive capacity.

 

The main handicap of Huntington’s disease is late diagnosis because 50 % of cells are dead when the disease is diagnosed. 

 

 

 

Diffusion tensor imaging

 

Diffusion tensor imaging is a non-invasive method for characterising microstructural organization of tissue in vivo. This technique demonstrates a significant white matter volume loss in pre-HD individuals.Subtle morphological alterations occur prior to neurons'death.

 

In Huntington’s disease patients, exploratory brain analyses might emphasise reductions in functional anisotropy in the internal capsule, frontal subcortical white matter and thalamus. Increases in functional anisotropy in the putamen in individuals affected can be found. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Brain volume loss analyses have demonstrated striatal volume loss is greater than any other structured examined. Basal ganglia regions volume loss is the most significant change occurred in patients. Brain structures may contribute together to disease or provide independent contributions. It has been demonstrated white matter volume loss determines the required number of years for clinical diagnosis more than striatal volume changes on their own.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

White matter atrophy and cortical thinning provide independent contributions. Significant cortical thinning is present in pre-HD individuals. So faster striatum and cerebral white matter atrophy occur in individuals affected.

 

 

 

 

Several positron emission tomography

 

This technique measures radioactively emissions from metabolically active chemicals transferred into bloodstream. PET measures might be altered before motor diagnosis in HD patients. These measures include pheripheral benzodiazepine binding using PK (C-(R)-PK11195) , glucose metabolism and D1/D2 dopamine receptor binding. HD patients present 2.3-10.9 % of changes in these measures per year. Decrease in glucose utilization precedes tissue loss (measured by structural imaging).

 

 

Functional MRI

 

This technique is used to detect abnormal patterns of brain activations associated with pre-HD and HD. Differences in activation patterns are found in HD patients. Impaired functional connectivity resulting in poor task performance have been found in HD patients. Reduced activations of the striatum and increased activations in cortical regions during a task have been found in pre-HD. 

 

Source: Paulsen, 2010