Application Of Dynamic Enhanced MRI In Evaluation Of Normal Kidney And Obstructive Kidney

Background and objective: Urological tuberculosis , tumor m calculus and trauma,etc.are frequently confronted factors that related to obstructive nephropathy, especially in adult patients. The renal dysfunction will emerge finally if, anyhow, the diagnosis and treatment could not be settled as soon as possible. In children, the most etiology of obstructive is congenital abnormity including congenital pelvic ureter junction obstruction(PUJO) and neugenic bladder, although the calculus and tumor are also frequently confronted. The diagnosis for the stenosis resulting from calculus and tumor is relative easy due to not only they had obvious apparent symptoms but also the ultrasonography, CT, intravenous urography(IVU) is pubular and precious in making diagnosis.. However, the evaluation of congenital hydronephrosis is facing the challenges. With ultrasound used popularly, more and more congenital hydronephrosis had been found, even in infant with no any clinical symptoms.The techniques routinely used in the clinics can not give forecast and whether exists of obstuctive hydronephrosis or non-obstuctive hydronephrosis, and when thesignificant pathological change of the kidney will occur. How to develop a modality to evaluate not only the figuration but also function, especially the individual kidney function regarding the concentrate and diluate ability, and to predict the prognosis, and to make sure if exist significan ureteral obstruction is a vital research dirction. MRI Gd-DTPA enhanced dynamics urography adopt fast gradient echo sequence to collect renal signal and can be used to know renal bloodflow variance and other renal function including excretion, concentration and dilution. By animal research, we had discovered that some special changes of signal intensity(SI) by Gd-DTPA in certain given region were coincident with functional estate of normal and obstructive kidney indicating this technique can diagnose obstructive nephropathy and provide additional renal functional information. The changed SI indicating the changing of renal blood flow and renal tubule's concentration and dilution function. Via integrate SI received from every region of kidney in different of time, we can evaluate renal configuration and function in patients with obstructive kidney in dynamic enhanced MRI. Therefore, the purposes of this study is to evaluate Gd-DTPA enhanced MRI could be used to evaluate the individual renal function of excretion, concentration and dilution as well as ureteral obstruction in human with congenital hydronephrosis. Methods1. Patients group Eight patients including 2 adults and 6 childs (8 male, aged from 4 to 57, averaged 23 year-old) with obstructive hydronephrosis, which had already been diagnosed by ultrasonography and CT were included in this study. On the other hand, 7 unilateral hydronephrotic kidneys were been evaluated as patient's team in 7 childs.2. Control group Eight healthy persons (7 male and 1 female, aged from 22 to 34, averaged 28.5 year-old) with normal kidneys (both sides, 16 kidneys) were included in this study. For another, the contra-side fine kidney as comparison and contrast results in 7 childs.3. Gd-DTPA enhanced MRI evaluation. The objectives were evaluated by Gd-DTPA enhanced MRI by using Siemens VB33D MRI. Non-ion paramagnetismcontrast medium (Omniscan,Gd-DTPA) was administered (0.2ml/kg body weight) intravously within 1 minute through foot vein. The patients were placed in a resupine position during the examination, body's loop, coronary TI weighted image, The index used in this study is TR-400ms, TE-15ms, layer thickness 5-10mm, collect 13 layer, matrix 256X256, field of view(FOV) is 350- 450mm, Acq 2 , and may scan axis in necessary. The rectangular 0.25 to 0.40 cm2 ROI (region of interesting) were selected in cortex , medulla -, pelvis of the kidney and its SI was collected at pre-contrast and post-contrast image (lmin, 3mim, 5min, 10min, 15min, 30min, 45min, 60min). RSI (relative signal intensity) was calculated by using the formula RSI = (SI post Gd-DT...