Reduction of noise in medullary renograms from dynamic MR images.
Dynamic magnetic resonance images of the kidney can be used to acquire separate renograms of the cortex and medulla. A high-quality cortical renogram can be determined directly from a region of interest (ROI) placed in the cortex. Due to partial volume effects, part of the signal from a ROI placed in the medulla is caused by cortical tissue. By subtracting a fraction of the cortical signal from the cortico-medullary signal, a purer medullary renogram can be obtained. A side effect of this subtraction is an increase in noise level. The noise level increases with larger partial volume fractions. Using a matched image filter, it is possible to exclude those areas from the ROI that have a high partial volume content, thus reducing the amount of cortical signal that has to be separated from the medullary signal. Noise reductions of up to 50% have been achieved in the medullary renogram, with an average reduction of 23%.
Giele
E L
EL
Department of Measurement and Control Systems, Eindhoven University of Technology, The Netherlands. eelco@stack.nl
de Priester
J A
JA
Blom
J A
JA
den Boer
J A
JA
van Engelshoven
J M
JM
Hasman
A
A
D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007672:Kidney Cortex / Q000473:pathology*; D007679:Kidney Medulla / Q000473:pathology*; D016030:Kidney Transplantation / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012815:Signal Processing, Computer-Assisted
D003287:Contrast Media; D019786:Gadolinium DTPA