The Clinical Investigate Of Reduced Radiation-Dose And Less Contrast MSCTU In Urinary Tract Obstruction

PURPOSE: To investigate the protocols of reduced radiation-dose andless contrast medium CT Scanning in Urinary tract obstruction, under thepremise of diagnosis quality requirements.MATERIALS AND METHODS:60cases with urinary tractobstruction disease were divided into three groups (80mA,100mA andconventional group) according to the different scanning tube current byGE lightspeed8slice spiral CT with120Kv of tube voltage,5mm layerthickness,8.75pitch,1.25mm thick layer and0.625mm interval ofreconstruction. In the80mA and100mA groups, delayed period scanswere taken in15minutes after intravenous injection with20ml ofContrast agents. In conventional group, multi-phases scans were takenwith85ml of contrast medium bolus injected at3~3.5ml/s, and onlydelayed period(15minutes delay) images included in this study. These images were reconstructed to MPR、VR、MIP and CPR, and reviewed bythree radiologists who were blinded to the cases. Taken the images ofconventional group as reference standard, image quality of80mA and100mA groups was evaluated to different level as below:4points, edgewas sharp and no artifact;3points, edge was sharp and some artifact;2points, edge was sharp and more artifact;1points, structure fuzzy. Datawere analyzed by SPSS13.0, and the random group variance testingmethod was applied between each two groups of80mA,100mA andconventional one.RESULTS: There was no significant difference of kidney and proximalureter transverse images, VR and MIP of urinary system between eachtwo groups in80mA,100mA and conventional MSCTU (P＞0.05).Significant difference of middle ureter transverse images, distal uretertransverse images, MPR and CPR of urinary system can be seen betweeneach two groups (P＜0.05). As to transverse images of bladder, there isno significant difference between groups80mA and100mA (P＞0.05),while significant difference can be found between group80mA andconventional method (P＜0.05). There is no significant differencebetween the100mA and conventional group of kidney, ureter, bladdertransverse images, VR, MIP, MPR and CPR of urinary system (P＞0.05).CONCLUSIONS: It would be efficiency to diagnose the upper urinarytract and kidney collecting system obstruction diseases by MSCTU when the tube current reduced to80mA and only20ml of contrast medium wasintravenously injected. Acceptable image quality would be meet thediagnostic requirements of whole urinary tract obstruction diseases whenthe tube current down to100mA and contrast medium down to20ml.