Feasibility of individualized low-dose CTU in the diagnosis of upper urinary tract obstructive diseases

Abstract

Objective To investigate the value of individualized low-dose computed tompgraphy urography (CTU) in diagnosing the upper urinary tract obstructive diseases. Methods A total of 112 patients with upper urinary tract obstruction underwent individualized low-dose CTU, conventional dosage plain scan (120 kV/300 mAs for adults, 120 kV/85 mAs for children), corti comedullary phase and parenchymal phase scan, at first; and then they underwent low-dose secretory phase scan with decreasing parameters according to the age of patients (120 kV/150 mAs for adults, 100 kV/50 mAs for children); at the same time, patients were given different enhanced scanning, and optimized scanning sequence according to pathogens and obstruction sites of upper urinary tract obstructive diseases. The volume data of all patients were reconstructed with 3D reconstruction techniques including maximum intensity projection (MIP), multiple plane reformation (MPR), and volume rendering technique (VR), and curve plane reformation(CPR). The diagnostic accuracy for CTU by intravenous pyelography (IVP) and magnetic resonance urography (MRU) were compared with the surgery and pathology results as standards. At the same time, the dose length product (DLP) of each case was recorded and the mean value was measured as the observation index of radiation dose. Results The individualized low-dose CTU was a non-invasive examination, compared with the surgical pathology and clinical treatment, its diagnastic accuracy for urinary stones, obstruction of plane and urinary tract malformation was 100%, which was significantly higher than the 82.2% (urinary stones), 75.4% (urinary tract malformation) of IVP and the 84.6% (urinary stones), 95.4% (urinary tract malformation) of MRU (P<0.05). At the same time, the qualified rate of low dose CTU reached 97.3%, while the radiation dose of CTU adults and children decreased by 53.5% and 65.4%, respectively. Conclusions The low dose CTU has significant advantages in the diagnosis of upper urinary tract obstruction. While ensuring the quality of the image, the low-dose CTU reduces the radiation dose on the patient significantly, which is a more human scanning method than conventional CTU. It can be used as the preferred imaging method for patients with upper urinary tract obstructive disease. Key words: Upper urinary tract obstructive diseases; Low-dose computed tompgraphy urography; Diagnosis