The Study of Renal Perfusion Image in Rabbit by Harmonic Ultrasound with Microbble Contrast Agent in Comparison with 99mTc-DTPA: Focusing on US Scan Technique and Concentration of Contrast Agent

PURPOSE: To compare the results of harmonic ultrasound (US) renal perfusion imaging using 99mTc-DTPA as contrast agent with those obtained when a microbubble contrast medium was used. MATERIALS AND METHODS: Twenty rabbits underwent harmonic US renal perfusion imaging using 99mTc-DTPA as contrast agent, and the imaging procedure was then repeated using a microbubble contrast medium. Three different concentrations of contrast media (200, 300 and 400 mg/ml) and two different scanning techniques (intermittent and continuous) were used, and the images obtained were assessed using six different methods. By means of a computer program, the images were converted to a renal perfusion curve and Tpeak values were calculated. Images obtained after use of the two different contrast media were compared. RESULTS: Tpeak at renal perfusion imaging using 99mTc-DTPA was 6.3+/-0.9 sec, and where microbubble contrast agent was used, the findings were was as follows: 13.8+/-1.6 sec (method 1), 6.5+/-1.1 sec (method 2), 14.8+/-1.7 sec (method 3), 6.6+/-1.0 sec (method 4), 15.2+/-2.0 sec (method 5), 6.4+/-0.7 sec (method 6). Method 6 had the highest correlation coefficients. CONCLUSION: In conclusion, the harmonic ultrasound renal perfusion images acquired using 99mTc-DTPA were similar to those obtained using microbubble contrast agent. Continuous scanning techniques showed correlation.

Which are Risk Factors developing Renal Cortical Defects on 99 mTc - DMSA Scintigraphy in Children with Acute Urinary Tract Infections?

PURPOSE: To determine (1) the relationship between the cortical defects seen on 99 mTc-DMSA renal scans and age, and (2) the presence and degree of vesicoureteral reflux, and then to depict the risk factors for cortical defects in children with acute urinary tract infection (UTI). Furthermore, to assess the diagnostic value of VCUG in predicting a defect on 99 mTc-DMSA renal scans. MATERIALS AND METHODS: We studied 134 kidneys in 67 children aged 15 days-10 years (M:F=39:28) in whom symptomatic UTI was present. In all these children, both DMSA renal scans and voiding cystourethrography (VCUG) were performed. Scanning took place within 7 days of diagnosis and VCUG was performed after one month of diagnosis. Scintigraphic findings were graded according to the extent and number of cortical defects. We evaluated the relationships between the cortical defects seen on DMSA scans and age, and the grade of vesicoureteral reflux. The diagnostic value of VCUG in predicting cortical defects was analysed. Results: The prevalence of cortical defects was greater in patients older than two years (38/54, 70%) than in those aged less than two (38/80, 48%). The frequency of cortical defects was related to vesicoureteral reflux (p or =2yrs) at the time of acute UTI, and high grade of vesicoureteral reflux. The specificity of VCUG in predicting cortical defects is relatively high but the sensitivitiy is low, and a significant proportion of cortical defects therefore occurred in the absence of vesicoureteral reflux.

CT of Acute Pyelonephritis in Children: Comparison with Tc-99m DMSA Scintigraphy

PURPOSE: The purpose of the study was to compare CT with scintigraphy in the detection of parenchymal lesionsof acute pyelonephritis in children, and to assess the diagnostic value of CT. MATERIALS AND METHODS: This studyinvolved 32 children with acute pyelonephritis ; their ages ranged from 1 month to 10 years. Renal CT , TC-99mDMSA planar and SPECT images, and medical records were retrospectively reviewed. We evaluated the number, size,shape, density, and location of pyelonephritic lesions, as seen on CT and scintigraphic images. RESULTS: In 43involved kidneys, 193 parenchymal lesions of acute pyelonephritis were identified. The results of CT were abnormalin 42 kidneys (98%), and those of scintigraphy, in 39(91%). CT showed single or multiple hypoenhancing parenchymallesions ; these were streaky(n=151), wedge-shaped (n=34), or oval (n=8), and ranged from about 3-30mm in maximumdiameter. Abscess (n=5), renal fascial thickening (n=6) and thickening of the bridging septae (n=7) wereassociated. Scintigraphic findings were diffuse or localized area of varying degrees of diminished corticalactivity, and these were more precisely identified on SPECT than on planar images. For the detection of 55 of 193pyelonephritic lesions, CT was more sensitive than scintigraphy ; 29 of the 55 lesions were less than 5 mm indiameter. CONCLUSION: For the detection of pyelonephritic lesions, particularly smaller ones, and for theevaluation of complications such as abscess formation, CT is more sensitive than Tc-99m DMSA scintigraphy. Weconclude that in children with subtle scintigraphic findings who are in serious clinical condition or in whomcomplications are suspected, CT is a useful tool for assessing a therapeautic plan and the prognosis of acutepyelonephritis.