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Magn Reson Imaging. 2018 Jan;45:120-128. doi: 10.1016/j.mri.2017.10.001. Epub 2017 Oct 12.

Validation of diffusion measurements obtained on a 0.35T MR in Malawi: Important insights for radiologists in low income settings with low field MRI.

Author information

1
Electrical and Computer Engineering, University of Rochester, Rochester, NY, United States.
2
Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, United States; Diagnostic Radiography and Radiation Sciences, Lusaka Apex Medical University, Lusaka, Zambia.
3
Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, United States; MRI Center, Queen Elizabeth Central Hospital, Blantyre, Malawi.
4
Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, United States.
5
Department of Neurology, University of Rochester Medical Center, Rochester, NY, United States; Epilepsy Care Team, Chikankata Hospital, Mazabuka, Zambia.
6
Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, United States. Electronic address: Jianhui_Zhong@URMC.Rochester.edu.

Abstract

PURPOSE:

To investigate the reliability of diffusion weighted image (DWI) measurements obtained on a 0.35T MR scanner in Malawi for malaria research.

MATERIALS AND METHODS:

The same healthy volunteers (n=6) were scanned on a 0.35T MR scanner in Malawi and a 3T scanner in the US. Three subjects had two repeated DWI scans at 0.35T. Due to scanner constraints, only three diffusion gradient directions for DWI on 0.35T could be obtained. An apparent diffusion coefficient (ADC) map was reconstructed from the 0.35T and the result was compared to standard DWI acquisition on the 3T scanner. The mean ADC from 15 different regions and the voxel-wise coefficient of variation (CV) were calculated to investigate the intra-scanner and inter-scanner variability. Reproducibility was calculated using intra-class correlation coefficient (ICC).

RESULTS:

The 0.35T intra-scanner ADC repeatability was high for all three subjects with repeated scans (ICC>0.7). The intra-scanner correlation between repeated scans was also high (r>0.67, p< 0.01). Comparing the ADC findings from the 0.35T and 3T MRs, the high inter-scanner correlation suggested that the 0.35T ADC results were valid (ICC>0.7, r>0.5, p<0.01). Voxel-wise CV revealed a few regions with larger variation (CV>20%), which were primarily located in peripheral regions and the boundary of lateral ventricles, and likely due to partial volume effects in low field scans.

CONCLUSION:

These findings support the validity of DWI obtained from low field MR scanners used in many low income countries.

KEYWORDS:

0.35T MR; ADC; Diffusion; Low field MRI; Lower income countries; Validation

PMID:
29031584
DOI:
10.1016/j.mri.2017.10.001
[Indexed for MEDLINE]

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