RSNA 2017: MRI helps predict motor deterioration in patients with Parkinson’s Disease

Magnetic resonance imaging (MRI)-based measurements of the brain’s white matter can help predict if a patient with Parkinson’s disease will develop motor deterioration, according to a study presented in a RSNA scientific session on Tuesday. Study findings suggest that diffusion tensor imaging (DTI) is potentially a useful tool in stratification of patients into clinical trials to monitor the impact of treatment on motor function.

Parkinson’s disease is a progressive disorder of the central nervous system, which affects one to two out of every 1,000 individuals, according to statistics from the National Institutes of Health.

Thais Minett, PhD, a specialist fourth-year trainee in radiology at Cambridge University Hospitals in the United Kingdom, investigated the use of DTI with MRI to detect changes to the brain’s white matter on a microstructural level, and to determine if these changes were predictors of declining motor impairment in Parkinson’s Disease.

The patient cohort evaluated by Dr. Minett and her colleagues included123 patients with early Parkinson’s Disease and 48 healthy indivudals. Both groups underwent clinical and motor (Movement Disorder Society Unified Parkinson’s Disease Rating Scale Part III) evaluations. They also had 3T MRI DTI scans. All these were repeated 18 months after the initial testing. The researchers analyzed DTI-generated measurements of mean diffusivity and fractional anisotropy and investigated their relationships with motor function. All analyses were controlled for age, sex, disease duration, levodopa dose, and visit intervals.

Patients with Parkinson’s Disease had significantly higher widespread mean diffusivity than the healthy patients. At follow-up, both groups showed a further significant fractional anisotropy decrease and mean diffusivity increase. The baseline mean diffusivity was a significant predictor of worsening of motor impairment in Parkinson’s disease, whereas fractional anisotropy was not a significant predictor.

Based on the study findings, Dr. Minett said that mean diffusivity represents an important correlate and predictor of motor impairment in Parkinson’s Disease. Mean diffusivity reveals how restricted diffusion of water is within the white matter, while fractional anisotropy represents the degree of directional infusion. DTI is potentially a useful tool in the stratification of patients into clinical trials and to monitor the impact of treatment on motor function.

“It may be that fractional anistropy reduction only occurs later in the course of disease progression,” Dr. Minett said. “Our cohort only included newly diagnosed Parkinson’s disease cases who had a mean disease duration of six months.”

“We could infer from my results that groups of patients with higher mean diffusivity would have more motor deterioration than those with lower mean diffusivity. So, identifying a group with higher likelihood of poor outcome may have important clinical relevance in terms of predicting prognosis, and therefore, the care pathway needed. More importantly, it may help in identifying a group with particular high need for therapeutic intervention who can be the subject of future trials,” she concluded.