Using CSF as an internal quality assurance tool in diffusion tensor imaging studies of brain tumor

Purpose: Diffusion tensor imaging (DTI) is an inherently quantitative imaging technique that measures the diffusivities of water molecules in tissue. However, the accuracy of DTI measurements depends on many factors such S/N ratio and magnet field strength. Therefore, before quantitative assessment of tumor progression based on DTI metric changes can be made with confidence, one have to assess the accuracy or variance in the DTI metrics. This is especially important for multi-institutional clinical trials or for large institutions where patients may be imaged on multiple MR scanners at multiple times in follow up studies. In this presentation, we studied the feasibility of using CSF as an internal QC marker for data acquisition and processing qualities. Method: ADC and FA of CSF for brain tumor patients' DTI studies (total of 85 scans over three years) were analyzed. In addition, a phantom was used to check the inherent variations of the MR systems. Results: The results show that the coefficient of variations for ADC and FA are 8.4% and 13.2% in CSF among all patients. For all DTI scans done on 1.5 T scanners, they are 7.4% and 9.1%, while for 3T they are 9.8% and 18% respectively. Conclusion: CSF can be used as an internal QC measure of the DTI acquisition accuracy and consistency among longitude studies on patients, making it a potentially useful in multi-institutional trials.