Seung-Koo Lee MD, PhD, Presenter: Nothing to Disclose

Eun Soo Kim, Abstract Co-Author: Nothing to Disclose

Decreased width, anisotropy and T1 signal are hallmarks of Parkinson disease because dopaminergic neurons of pars compacta degenerate in advance disease. The purpose of this study was to evaluate clinical feasibility of T1 and T2* relaxometry in diagnosis of Parkinson disease (PD) by assessing changes of substantia nigra.

Forty two consecutive patients (M:F=19:23, 66.4 years) clinically diagnosed to have PD and 31 age-matched healthy volunteers (M:F=9:22, 65.8y) were enrolled. All studies were performed on 3T MRI system (Achieva, Philips Healthcare, Best, The Netherlands). The T1 and T2* relaxation time were measured at the level of midbrain. The basis sequence of T1 measurement was used IR TFE multi-shot Look-Locker sequence with 5mm thickness, 23cm FOV and 256 matrixes. A single slice image was acquired in 9 shots. Each shot consisted of multiple inversion pulses of 10° to measure T1 signal recovery curve, and ended with a recovery time of 8000 ms. For T2 * measurement, multiple FFE sequence was used. Based on previous studies, pars reticulata (SNr) was identified as low signal area at ventromedial part of crus cerebri and pars compacta (SNc) as high signal interposed between SNr and the red nucleus (Figure 1D and 2D). ROIs were placed at SN with free hand technique by two experienced neuroradiologists. Statistical analysis was performed with SPSS 16 for window. Differences in T1 and T2 star relaxation time measurements between patients and controls were evaluated using independent two-tailed Student’s t-test. A p-value less than 0.05 were considered statistically significant.

T1 relaxation time of substantia nigra was higher in PD than control group (Rt : 1040.00 ± 51.25 vs 960.38±52.24, p=0.0001 ; Lt: 1037.60 ± 51.76 vs 956.35 ± 49.26, p=0.0001 independent t-test, two-tailed) (Fig 3 A and B). T2* relaxation time was lower in PD, but it was not statistically significant (Fig 3 C and D).

T1 relaxometry can detect increased local T1 relaxation time in PD due to decreased neuromelanin content after depletion of dopaminergic neurons. Changes of T2* relaxation time is also seen in PD due to iron accumulation but not specific and also can be seen in normal aging process.

T1 relaxometry can be a qunantitative analysis in Parkinson disease and it will be promising in monitoring of treatment and clinical course.

Lee, S, Kim, E, Quantification of Substantia Nigra by T1 and T2* Relaxometry in Parkinson Disease.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11010467.html