Assessment of the Renal Length Measurement Accuracy on Spiral CT scan with Multiplanar Reconstruction of Images(MPR) in Hashemi Nejad Hospital in 2004

Measuring the length of kidneys is an important issue in diagnosis and treatment of renal diseases. In various diseases, kidneys become larger or smaller than normal. Ultrasonography is a suitable method for measuring renal length because it is accurate, noninvasive, available and with low cost. Nowadays, multislice spiral CT scanners are widely used for evaluation of renal diseases and are capable of making different reconstructions on images including multiplanar reconstruction(MPR) and in many situations, measurements like measuring renal length are done on these reconstructed images. Hence, knowing the accuracy of measurements on reconstructed images is very important. This research was done to evaluate the accuracy of renal length measurement on multiplanar reconstructed images of spiral CT scan.Patients & In a cross-sectional study, spiral CT scan was performed on all of the patients referred to CT scan department of Hashemi Nejad Hospital for abdominal CT scan during July and August 2004. Multiplanar reconstruction was carried out on all of the images and the maximum length of kidneys was measured. Then ultrasonography was done for all of the patients and the maximum length of kidneys was measured as gold standard. The lengths of kidneys obtained from these two methods were compared with each other. 40 patients(80 kidneys) with the mean age of 42 years were evaluated. Analysis with SPSS and paired t-test revealed that the mean renal length at ultrasonography was 107.1 mm with standard deviation of 12.08 and the mean renal length at spiral CT scan was 110.18 mm with standard deviation of 11.93. The mean length of kidneys resulted from ultrasonography was 3.08 mm less than the mean length of kidneys resulted from multiplanar reconstructed images of spiral CT scan, and considering P<0.05, the difference was considered significant. Measuring the renal length on reconstructed images doesn’t have enough accuracy. Therefore, in situations when knowing the exact size of the kidney is important, measurements should be done on the basic CT images(without reconstruction) or on other methods like ultrasonography.