Dopamine transporter imaging for the diagnosis of multiple system atrophy cerebellar type

The added value of dopamine transporter SPECT (DAT-SPECT) for the diagnosis of "possible" multiple system atrophy of the cerebellar type (MSA-C) remains unknown.

We reviewed retrospectively the charts of 128 consecutive patients with a clinical diagnosis of MSA-C who were seen between 2007 and 2016 at the French Reference Center for MSA. The main objective was to evaluate the proportion of patients for whom the diagnosis of "possible" MSA-C was made because of a positive DAT-SPECT.

Seventy-eight MSA-C patients had at least one DAT-SPECT. Fifty-nine of them were considered for the final analysis. In these, 22 had "possible" MSA-C and 23 "probable" MSA-C before DAT-SPECT, while 14 did not reach diagnosis criteria at that time. In those with "possible" MSA-C, DAT-SPECT was positive in 64%. In patients with "probable" MSA-C, 83% showed nigrostriatal denervation. Six out of 14 (43%) received a diagnosis of "possible" MSA-C because of positive DAT-SPECT. These patients had mean disease duration of 2.3 years at the time of DAT-SPECT compared to 3.5 years of the entire cohort of MSA-C patients with DAT-SPECT. Of the eight remaining, one had positive DAT-SPECT but also pons atrophy on magnetic resonance imaging, and seven progressed to "probable" MSA based on clinical features.

Our results suggest that DAT-SPECT significantly contributes to the diagnosis of "possible" MSA-C (43% of patients not reaching consensus diagnosis criteria before DAT-SPECT). DAT-SPECT seems especially useful in patients with shorter disease duration, while a negative result does not exclude a diagnosis of MSA.