In a paper published on-line yesterday (https://doi.org/10.1007/s10072-021-05223-0), Minkyeong Kim and Seulki Yoo (two lead authors) presented results of an iron-sensitive MRI biomarker study in early Parkinson's diseases patients. This work started in 2017 as part of a broader 3T neuro MRI collaboration between SKKU and SMC, with the SMC team led by Drs. Jin Whan Cho and Jinyoung Youn.
At least 19 PD patients and 16 normal volunteers were brought from SMC to SKKU for a 3T MRI scan, from which 14 patients and 12 healthy subjects' data were selected for analysis of iron-sensitive MR imaging. Part of the funding came from IBS, and part from SKKU intramural research grant of 2019.
For a clinical study the work used relatively small number of samples. The novelty claim has been laid on the use of relatively homogeneous, early-stage PD patients and investigation of non-motor symptoms. The main finding of the paper is the existence of non-negligible correlation between certain non-motor symptoms (such as sleep disorder) and R2* values in deep brain regions (such as red nucleus, amygdala, and hippocampus). Since R2* is sensitive to tissue iron level, this observation suggested that iron in specific brain regions of PD patients may be indicative of non-motor clinical symptoms.
Despite much effort and time spent in data collection and analysis, the study exposed limitations of using iron-sensitive MRI for clinical research. Most significantly from the Lab's point of view, the QSM results were highly variable among subjects, to a degree much greater than inter-group differences expected from early PD cohorts. Motion, head orientation, and other physiological factors appear to affect QSM much more than R2* and other established, magnitude-based contrasts.
This observation, made early on in the project, strongly suggested the need of longitudinal studies to follow variation of QSM on individual subjects. Such studies can greatly benefit from the ability to post-process routine clinical MR scans collected in SMC. To this end, the team has looked into the possibility of including multi-echo GRE scans, including phase images, in the routine scan protocol at SMC. Hopefully this line of research will continue in the near future for more fruitful clinical collaboration.
