Opacification Of Collecting System Research Articles

Split-bolus CT urography after microwave ablation of renal cell carcinoma improves image quality and reduces radiation exposure.

To compare image quality and radiation dose between single-bolus 2-phase and split-bolus 1-phase CT Urography (CTU) performed immediately after microwave ablation (MWA) of clinically localized T1 (cT1) RCC. Forty-two consecutive patients (30M, mean age 67.5 ± 9.0) with cT1 RCC were treated with MWA from 7/2013 to 12/2013 at two academic quaternary-care institutions. Renal parenchymal enhancement, collecting system opacification and distention and size-specific dose estimate (SSDE) were quantified and image quality subjectively assessed on single-bolus 2-phase versus split-bolus 1-phase CTU. Kruskal-Wallis and Pearson's Chi-squared tests were performed to assess differences in continuous and categorical variables, respectively. Two-sample T test with equal variances was used to determine differences in quantitative and qualitative image data. Median tumor diameter was larger [2.9cm (IQR 1.7-5.3) vs 3.6cm (IQR 1.7-5.7), p = 0.01] in the split-bolus cohort. Mean abdominal girth (p = 0.20) was similar. Number of antennas used and unenhanced CTs obtained before and during MWA were similar (p = 0.11-0.32). Renal pelvis opacification (2.5 vs 3.5, p < 0.001) and distention (4mm vs 8mm, p < 0.001) were improved and renal enhancement (Right: 127 HU vs 177 HU, p = 0.001; Left: 124 HU vs 185 HU, p < 0.001) was higher for the split-bolus CTU. Image quality was superior for split-bolus CTU (3.2 vs 4.0, p = 0.004). Mean SSDE for the split-bolus CTU was significantly lower [163.9mGy (SD ± 73.9) vs 36.3mGy (SD ± 7.7), p < 0.001]. Split-bolus CTU immediately after MWA of cT1 RCC offers higher image quality, improved opacification/distention of the collecting system and renal parenchymal enhancement at a lower radiation dose.

Optimization of 64-MDCT Urography: Effect of Dual-Phase Imaging With Furosemide on Collecting System Opacification and Radiation Dose

The purpose of this study was to compare opacification of the urinary collecting system and radiation dose associated with three-phase 64-MDCT urographic protocols and those associated with a split-bolus dual-phase protocol including furosemide. Images from 150 CT urographic examinations performed with three scanning protocols were retrospectively evaluated. Group A consisted of 50 sequentially registered patients who underwent a three-phase protocol with saline infusion. Group B consisted of 50 sequentially registered patients who underwent a reduced-radiation three-phase protocol with saline. Group C consisted of 50 sequentially registered patients who underwent a dual-phase split-bolus protocol that included a low-dose furosemide injection. Opacification of the urinary collecting system was evaluated with segmental binary scoring. Contrast artifacts were evaluated, and radiation doses were recorded. Results were compared by analysis of variance. A significant reduction in mean effective radiation dose was found between groups A and B (p < 0.001) and between groups B and C (p < 0.001), resulting in 65% reduction between groups A and C (p < 0.001). This reduction did not significantly affect opacification score in any of the 12 urinary segments (p = 0.079). In addition, dense contrast artifacts overlying the renal parenchyma observed with the three-phase protocols (groups A and B) were avoided with the dual-phase protocol (group C) (p < 0.001). A dual-phase protocol with furosemide injection is the preferable technique for CT urography. In comparison with commonly used three-phase protocols, the dual-phase protocol significantly reduces radiation exposure dose without reduction in image quality.

Influence of bladder distension on opacification of urinary collecting system during CT urography

The purpose of the study was to evaluate and compare opacification of the renal collecting system and ureters detected by computed tomographic urography (CTU) performed 20 min and 1 h after the ingestion of 1,000 ml of water. CTU was performed on 89 patients (55 men, 34 women; age 28-77 years) and 168 collecting systems and ureters were evaluated. A 16-detector-row scanner (Sensation 16, Siemens) was used; a two-phase protocol with a split bolus of contrast agent (total 120 ml) was applied. A combined nephrographic-excretory phase was obtained 100 s after the second injection. Three-dimensional reconstructions of the excretory phase were created and used to evaluate the degree of opacification of the collecting system and ureters. In 44 patients, water was administered 20 min before examination, and in 45 patients, 1 h before examination. CTU performed 1 h after water ingestion demonstrated complete opacification of calices in 87.5%, of renal pelvis in 97.5%, of upper ureter in 91.8% and of lower ureter in 87.5% of patients. CTU performed 20 min after water ingestion demonstrated complete opacification of calices in 79.5%, of renal pelvis in 85%, of upper ureter in 62.5% and of lower ureter in 54.5% of patients. Complete opacification of the proximal and distal ureter in the group with a 1-h delay was statistically higher (P<0.01). CTU performed on the distended bladder, 1 h after the oral ingestion of water, enables excellent opacification of collecting system, including distal ureters.

Another Method for Localization of Radiolucent Urinary Stones during ESWL

Objectives: 1. To study the feasibility and safety of localization of radiolucent urinary stones during ESWL utilising the refluxing intravesically injected contrast medium along indwelling ureteral stents. 2. To identify the optimum volume of contrast medium and the intravesical pressure at which adequate vesicoureteral reflux sufficient for collecting system opacification occurs. 3. To identify criteria by which successful localization can be predicted. Methods: With antibacterial prophylaxis, hundred mls. of contrast medium diluted with 500 ml normal saline was infused into the bladder through a Y shaped connection attached to a pre-inserted urethral catheter with the other limb connected to a water manometer for the purpose of continuous intravesical pressure recordings. The amount of infused contrast medium and intravesical pressure at which adequate visualization by fluoroscopy occurred was recorded. Successful stone localization was correlated with the infused contrast medium volume, intravesical pressure, infection, stone location, age, weight, stent duration and fluoroscopy time. Results: Forty six patients were studied. Clear stone localization to facilitate shock targeting was achieved in 37 patients (80%). This occurred with a mean contrast volume of 300 ml at 20 cm water mean intravesical pressure. Apart from urinary tract infection which was associated with a significantly lower success rate, there were no other criteria by which success can be predicted. There were no significant complications and all visualized stones disintegrated well and were completely cleared at 3 months. Conclusions: The method is safe, easy, repeatable and suitable for targeting radiolucent urinary stones during ESWL in patients with ureteral stents Sudan Journal of Medical Sciences Vol. 2 (2) 2007: pp. 81-84

Comparison of Urinary Tract Distension and Opacification Using Single-Bolus 3-Phase vs Split-Bolus 2-Phase Multidetector Row CT Urography

To compare urinary tract distension and opacification obtained with single-bolus 3-phase and split-bolus 2-phase multidetector row computed tomographic urography (CTU) techniques. Twenty-six single-bolus 3-phase CTU examinations were retrospectively compared with 26 split-bolus 2-phase examinations. Two readers reviewed excretory-phase imaging to record quantitative measurements of urinary tract distension and qualitative measurements of urinary tract opacification. Single-bolus 3-phase CTU technique provided better overall urinary tract distension than did split-bolus 2-phase technique (P = 0.05). Single-bolus CTU images demonstrated superior lower pole and interpolar region intrarenal collecting system distension when compared with split-bolus CTU images (P < or = 0.04). Qualitative opacification scores for the lower urinary tract were significantly higher, using single-bolus technique for only 1 of 2 reviewers. No significant differences between techniques in intrarenal collecting system opacification, ureteral distension, or ureteral opacification were identified. Improved urinary tract distension is obtained with single-bolus 3-phase CTU technique.

Opacification of the Genitourinary Collecting System During MDCT Urography with Enhanced CT Digital Radiography: Nonsaline Versus Saline Bolus

The purpose of this study was to determine whether a saline bolus during CT urography improves urinary collecting system opacification and whether the addition of enhanced CT digital radiography (CTDR) improves urinary collecting system visualization with or without a saline bolus. One hundred eight CT urography and enhanced CTDR examinations were reviewed. Fifty-four patients were given a saline bolus during CT urography, and 54 patients underwent CT urography without a saline bolus. Urinary collecting system opacification was evaluated by group (saline vs nonsaline), imaging technique (CT urography alone vs CT urography plus enhanced CTDR), number of enhanced CTDR images, and site of nonopacified urinary segments. Using a multivariate logistic regression model, we determined significance of variables and odds of complete opacification. In the saline group, 248 nonopacified sites were identified on CT urography alone and 95 sites with CT urography plus enhanced CTDR. In the nonsaline group, 185 nonopacified sites were identified on CT urography alone and 59 sites with CT urography plus enhanced CTDR. Combining both groups, 433 nonopacified sites were identified with CT urography alone and 154 sites with CT urography plus enhanced CTDR. Multivariate logistic regression showed significance for group (p = 0.010), imaging method (p < 0.0001), number of enhanced CTDR images (p = 0.048), and site of segment opacification (p < 0.0001). The renal pelvis shows the greatest odds and the distal ureter the lowest odds for complete opacification by group or imaging method. The addition of a saline bolus offers no improvement, whereas the addition of enhanced CTDR offers significant improvement in collecting system opacification during CT urography.

RETROGRADE RENAL COOLING DURING RADIO FREQUENCY ABLATION TO PROTECT FROM RENAL COLLECTING SYSTEM INJURY

We evaluated the protective effect of continuous retrograde irrigation of ice-cold saline on the renal collecting system during central parenchymal temperature based radio frequency ablation (RFA). In 10 domestic pigs bilateral, centrally located renal parenchymal RFA lesions (intended 2 cm in diameter) were created that intentionally involved the collecting system. RFA probe placement was guided by fluoroscopy with retrograde collecting system opacification and simultaneous direct laparoscopic visualization. In 1 renal unit RFA was performed while infusing ice-cold saline through a previously placed ureteral access sheath and pigtail stent. RFA without renal cooling was performed in the contralateral renal unit. Kidneys were harvested at 7 days. The renal collecting system was inspected for injury by performing retrograde pyelograms and by histological examination of the collecting system adjacent to the ablation zone. The size of RFA lesions was measured. In retrograde cooling procedures the temperature of saline irrigant was -1.0C and the mean temperature of the effluent was 13C. One of 10 cooled renal units demonstrated contrast material extravasation from the collecting system involved by the ablation zone compared with 7 of 10 noncooled renal units (p = 0.025). Lesion size was comparable between cooled kidneys and controls (2.67 and 2.72 cm, respectively, p = 0.629). Retrograde renal cooling helps protect the renal collecting system from injury during RFA without a decrease in expected lesion size. Clinically retrograde renal cooling may decrease the risk of collecting system injury and subsequent complications during RFA.

Effectiveness of Abdominal Compression During Helical Renal CT

Rationale and Objectives The authors performed this study to assess the effect of abdominal compression on opacification and distention of the proximal renal collecting system during helical computed tomography (CT). Materials and Methods Abdominal compression was applied during helical CT in 31 patients who were scanned 150 and 300 seconds after initiating a dynamic bolus injection of contrast material. Two reviewers assessed renal collecting system opacification and measured the maximal short-axis diameter of the collecting system at three locations: the upper pole, the lower pole, and the proximal ureter. A similar evaluation was performed in a control group of 29 patients who underwent CT without compression at 300 seconds after initiating the injection of contrast material. Results Both reviewers noted collecting system opacification at all locations in 52 of 56 noncompressed collecting systems scanned at 300 seconds, 57 of 59 compressed collecting systems scanned at 300 seconds, but only 26 of 59 compressed collecting systems scanned at 150 seconds. Measured collecting system distention was statistically significantly greater at 300 seconds in patents who received compression than in patients who did not ( P = .0013). For patients who received compression, measured collecting system distention was statistically significantly greater on scans obtained at 300 seconds than on scans obtained at 150 seconds ( P = .0001). Conclusion Abdominal compression during renal helical CT produces a detectable increase in renal collecting system distention. In patients who receive compression, scanning at 300 seconds rather than at 150 seconds results in greater collecting system distention and more consistent opacification.