Charles R. Meyer, Ph.D. [1]
Peyton H. Bland, Ph.D. [1]
James Pipe, Ph.D. [1,2]
[1] Department of Radiology, University of Michigan, Ann Arbor, MI 48109-0553
[2] Currently: Harper Hospital, Wayne State University, Detroit, MI
Abstract
Medical imaging data sets are often corrupted by multiplicative inhomogeneities, often referred to as nonuniformities or intensity variations, that hamper the use of quantitative analyses. We describe an automatic technique that not only improves the worst situations such as those encountered with magnetic resonance imaging (MRI) surface coils, but also corrects typical inhomogeneities encountered in routine volume data sets such as MRI head scans without generating additional artifact. Because the technique uses only the patient data set, the technique can be applied retrospectively to all data sets, and corrects both patient independent effects such as rf coil design, and patient dependent effects such as attenuation of overlying tissue experienced both in high field MRI and x-ray computed tomography (CT). We show results for several MRI imaging situations including thorax, head, and breast. Following such corrections, region of interest analyses, volume histograms, and thresholding techniques are more meaningful. The value of such correction algorithms may increase dramatically with increased use of high field strength magnets and associated patient-dependent rf attenuation in overlying tissues.
Images
associated with this work may be viewed on-line.
An overview (text and images)
on retrospective correction may be viewed on-line.
Keywords:
Inhomogeneity, background, nonuniformity, correction, retrospective,
image processing, MRI, x-ray CT
Meyer, C.R., P.H. Bland, and J. Pipe: Retrospective correction of intensity inhomogeneities in MRI and CT. IEEE Transactions on Medical Imaging, 14(1):36-41, 1995.
This work supported in part by DHHS PHS grants NIH 1R01CA52709 and 1F32CA09309.
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