Josef Vymazal MD,PhD, Presenter: Consultant, EPIX Pharmaceuticals, Inc, Boston, MA Consultant, NovoCure Ltd, Haifa, Israel

Jiri Klempir MD, Abstract Co-Author: Nothing to Disclose

Robert Jech MD,PhD, Abstract Co-Author: Nothing to Disclose

Jana Zidovska MD, Abstract Co-Author: Nothing to Disclose

Evzen Ruzicka MD,PhD, Abstract Co-Author: Nothing to Disclose

Jan Roth MD,PhD, Abstract Co-Author: Nothing to Disclose

To investigate the relationship between T2 relaxation time (T2), the number of cytosine-adenine-guanine triplet repeats (CAG) that characterize the disease and clinical status in patients suffering from Huntington’s disease (HD)

33 HD patients (50.1 (mean) ± 11.7 (SD) years) and 34 control subjects (49.3 ± 13.3 years) were scanned using a 1.5 Tesla scanner and underwent clinical and genetic testing. The number of CAG in mutant allele was determined. A multiple echo spin echo sequence was employed for T2 measurements. Non-parametric statistical tests were used for the analysis.

T2 from healthy volunteers matched previous studies and linearly correlated with published iron concentrations. A T2 shortening was found in the pallidum of HD patients compared to controls (P<0.00001). A correlation between the number of CAG and T2 was found for the left pallidum (decrease in T2, P<0.05) and an inverse correlation for the left caudate (increase in T2, P<0.05).

In HD patients, alterations in iron levels may be caused by an alteration in its axonal transport. The T2/CAG covariations in the left pallidum and left caudate may reflect changes in levels and forms of iron: this suggests that HD patients with a higher genetic load have more ferritin-bound (“safe form”) iron in the left pallidum and/or more low-molecular (“toxic”) iron in the left caudate. The increase in the total amount of iron in the striatum has been published elsewhere. An increase in “toxic” iron in the caudate enables oxidative stress and thus progression of the disease.

This is the first correlation between the genetic tests (CAG) and in vivo T2 measurements in HD. The results show the role of iron accumulation and its forms in physiopathology of HD.

Vymazal, J, Klempir, J, Jech, R, Zidovska, J, Ruzicka, E, Roth, J, Huntington Disease: Correlation between Quantitative MR Imaging, Genetic, and Clinical Results.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4427935.html