[en] Purpose: To develop and evaluate a method of calculating split renal function from computed tomography (CT) images based on the assumption that the accumulation of contrast medium is proportional to the renal function, and to compare the results with the renogram. Material and Methods: The study comprised a retrospective analysis of CT images and renograms from previous donors. Twenty-seven potential renal donors were studied using a technique for measuring the area and mean attenuation of the separate CT slices, and for calculating the volume and total attenuation of the whole kidney. Results: Correlation between CT and renography was moderate (r=0.43), but the range of results was narrow. The ratio between the two kidneys was more even with CT (50±2.1%) than with the renogram (48±2.9%) (right kidney), and the mean difference between the two methods was 3±2.3 percentage points. Conclusion: The renogram can be replaced using calculations from the CT examination in estimating split renal function in potential renal donors

[en] Purpose: To investigate whether three-dimensional rotational angiography (3D-RA) of the transplant renal artery performed with an extended angle of rotation can reduce beam-hardening artifacts in 3D reconstructed images without image quality being lost or side effects to the transplanted kidney being increased. Material and Methods: 3D-RA with a C-arm rotation of 180 deg was performed consecutively in 12 renal transplanted patients with suspicion of renal artery stenosis. A 1.7-mm balloon occlusion catheter was placed using the crossover technique and this was compared to a protocol with 160 deg rotation and a traditional 1.4-mm catheter in 10 patients. The occurrence of beam-hardening artifacts was registered and the effects of the reduced contrast load on image quality and of arterial occlusion on renal function were assessed. Results: The extended angle of rotation, from 160 deg to 180 deg, reduced the beam-hardening artifacts. Artifacts were observed in 4/11 patients (36%) in the study group and in all 10 (100%) of the controls. There was no statistical difference regarding image quality between the two protocols. Renal function was equally affected in both protocols. Conclusion: 3D-RA with an extended C-arm rotation reduced the beam-hardening artifacts. Image quality was not reduced despite the reduced contrast medium load. The different protocols had no effect on patient outcome

[en] Purpose: To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. Material and Methods: Thirty-eight patients, aged 65.7±11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99m Tc-MAG3 with or without captopril enhancement was used as a reference. Results: The 2D CT method had good correlation with renography (r = 0.93). Mean difference was 4.7±3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r = 1.00). Conclusion: CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique