Extravascular background subtraction using deconvolution analysis of the renogram.
The effect of the intravascular background in the renogram on the calculated renal retention function is known and can be removed. However, the effect of the extravascular background (EVB) has not been thoroughly investigated using patient data. By varying the size of the region of interest containing a single kidney and by deconvolving the 131I-hippuran and 99Tcm-DTPA renograms so generated, the following has been found: (a) the effect of EVB on the mean transit time (MTT) is negligible and EVB subtraction is not necessary, (b) the EVB overestimates the lower relative kidney function (RKF) and underestimates the higher RKF, so that EVB subtraction should be performed if the RKFs are asymmetric. A new method is described in which the correction for EVB is performed following deconvolution. If the RKFs are greater than about 30%, the correction can be performed using a regression equation between the RKFs corrected for EVB and those that are not corrected. When the RKFs are asymmetric to a greater extent, the correction should be performed for each study separately. The proposed method includes a small systematic error due to the inherent limitations of nuclear medicine equipment.
Basić
M
M
Department of Nuclear Medicine, Clinical Hospital Centre-Rebro and Medical Faculty, Zagreb, Yugoslavia.
Popović
S
S
Macković-Basić
M
M
Sedlak-Vadoc
V
V
Bajc
M
M
D000328:Adult; D002648:Child; D006801:Humans; D007465:Iodohippuric Acid; D009942:Organometallic Compounds; D004369:Pentetic Acid; D011866:Radioisotope Renography / Q000379:methods*; D016284:Technetium Tc 99m Pentetate
D009942:Organometallic Compounds; D007465:Iodohippuric Acid; D004369:Pentetic Acid; D016284:Technetium Tc 99m Pentetate