The aim of the study was to assess the sensitivity of magnetic resonance urography (MRU)-both native and contrast-enhanced examinations-in the diagnosis of ureteral strictures and to evaluate its importance in the diagnostic algorithm in patients with different causes of urinary obstruction. Materials and Methods. MRU was performed in 62 patients with ureteral strictures, whose average age was 47±9.8 years, using high-field MRU devices Vantage Atlas (Toshiba, Japan) and Ingenia (Philips, the Netherlands) with magnetic field intensities of 1.5 and 3.0 T, respectively. The strictures were primary in 6 cases and secondary (acquired) in 56. In 42 cases (67.7%), excretory MRU was carried out: the procedure involved intravenous administration of contrast agent. The detected strictures were evaluated in terms of localization, shape, extension and suprastenotic dilatation extent. The technique sensitivity in detecting the changes in surrounding structures was also estimated: ureteral wall thickening and paraureteral tissue infiltration were evaluated, the spread of tumor process was assessed when appropriate. The results obtained by computed tomography urography (CTU) and confirmed by surgical intervention were considered as reference values. Results. MRU sensitivity in the diagnosis of ureteral strictures was 96.3%. The technique showed the best results in the lower third of the ureters: 100% of strictures were identified regardless of their origin. In the upper third, MRU confirmed the strictures detected on CTU in 97.2% of cases. As for the middle third of the organ, the results were lower than on CTU: 87.4% of strictures were detected. According to excretory MRU data, the following pathological symptoms were revealed: organ obstruction-in 62 cases (100%), filling defect-in 9 cases (14.5%), suprastenotic dilatation-in 56 cases (90.3%), hydronephrosis-in 52 cases (83.9%), pelvicalyceal system dilationin 58 cases (93.5%). Besides, traditional MR sequences, especially the series with suppression of the signal from adipose tissue, are highly sensitive to edema manifestations and revealed infiltrative changes in the surrounding tissue in 34 (54.8%) and ureteral wall thickening in 45 cases (72.5%). Accumulation of fluid in the pelvis was found in 8 cases (12.9%). MRU also made it possible to detect changes in parenchymal organs, the liver, adrenal glands and to suspect the presence of secondary pelvic bone lesions. Conclusion. Contrast-enhanced MRU demonstrates high efficacy in detection of ureteral strictures similarly to CTU and, in case of obstruction located in the lower third of the organ, it is superior to CTU and provides additional information about the condition of the organ wall and the surrounding tissues. Non-contrast MRU provides the possibility to clearly localize the level of obstruction and identify its cause. The absence of ionizing radiation makes the technique successfully applicable in patients with contraindications to CTU.
Objective. To assess the sensitivity of computed tomography urography (CTU) and magnetic resonance urography (MRU) (native versus contrast-enhanced studies) in patients with traumatic ureteral strictures.Material and methods. The data of 51 CTUs and 34 MRUs made in patients with upper urinary tract injuries were prospectively analyzed. The studies were performed using an Aquilion Prime 160-slice scanner (Toshiba, Japan) and high-field devices at a magnetic field strength of 1.5 Tesla Vantage Atlas (Toshiba, Japan) and at 3.0 Tesla Ingenia (Philips, Netherlands). Excretory urography was also carried out in 92.2% of cases; ultrasound examination was made in 74.5%. The degree of obstruction, its causes, the state of the adjacent structures, and the presence of complications were assessed.Results. All (100%) CTU studies correctly estimated the level of stricture of the ureter; the lower third of the organ was involved most frequently (68.6%). MRU identified traumatic strictures in 94.0% of cases. MRU and CTU could be confined to native series in 51.0 and 27.5% of patients, respectively. MRU more commonly revealed the changes concurrent with injuries: there was diffuse ureter wall thickening in 44.1% (27.5% at for CTU), periureteral fat infiltration in 43.1% (37.2% at CTU), and pelvic fluid accumulation in 9.8% (7.8% at with CTU). The techniques could also establish the presence of sinus tracts: MRU was useful in the preoperative imaging of pathological fistulas in 100%. CTU was able to demonstrate the leakage of a contrast agent and/or its flow into the vagina in 66.7%.Conclusion. MRU demonstrates the sensitivity comparable to that of CTU in detecting ureteral injuries (including in diagnosing complications, such as fistulas) and can be used in patients with contraindications to CTU and, due to the absence of ionizing radiation, for follow-up studies.
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