Four‐dimensional CT excretory urography is an accurate technique for diagnosis of canine ureteral ectopia

Abstract

Computed tomographic (CT) excretory urography is commonly used to investigate canine ureteral ectopia (UE). Modern technology allows time‐resolved CT imaging (four‐dimensional CT excretory urography [4D‐CTEU]) over a distance exceeding the detector collimation. Objectives of this prospective, observational, diagnostic accuracy study were to evaluate the diagnostic accuracy of CT excretory urography (CTEU) and 4D‐CTEU for UE in dogs with lower urinary tract signs, assess the influence of pelvis positioning, and to determine the significance of the ureterovesical junction (UVJ) angle for UE diagnosis. Thirty‐six dogs, with a total of 42 normotopic ureters, 27 intramural ectopic ureters, and three extramural ectopic ureters, underwent CTEU and 4D‐CTEU with randomized pelvis positioning. Randomized CTEU and 4D‐CTEU studies were scored by two observers for ureteral papilla location and murality on a grading scheme. Interobserver agreement, sensitivity, and specificity for ureter topia status and diagnosis were calculated. Computed tomographic excretory urography showed moderate interobserver agreement for the left ureter and perfect for the right ureter, whereas 4D‐CTEU showed bilateral nearly perfect agreement between both observers. When comparing CTEU versus confirmed diagnosis, there was a sensitivity and specificity of 73% and 90.2%, respectively, whereas 4D‐CTEU showed a sensitivity and specificity of 97% and 94.6%, respectively. An obtuse UVJ angle is significantly more commonly observed in ectopic intramural than normotopic ureters and is significantly associated with increased diagnostic confidence of UE. The use of a wedge to angle the pelvis did not increase the diagnostic confidence in determining ureteral opening position. Four‐dimensional CT excretory urography is an accurate and reliable diagnostic technique to investigate UE as cause of urinary incontinence in dogs that is slightly superior to CTEU.

Ultrasonography as a sensitive and specific diagnostic modality for the detection of ectopic ureters in urinary incontinent dogs

“…This is similar to the previously reported sensitivity of 91% for AUS diagnosis of ureteral ectopia when compared to contrast radiography 14 . The AUS sensitivity reported in this study is similar to that of CT, lower than that of 4D‐CTEU, and greater than that of intravenous urography 10,12 . The specificity of AUS for EU has not been previously reported.…”

“…14 The AUS sensitivity reported in this study is similar to that of CT, lower than that of 4D-CTEU, and greater than that of intravenous urography. 10,12 The specificity of AUS for EU has not been previously reported. AUS has the benefit that it allows the thorough evaluation of the abdominal viscera, urinary tract, and concurrent abnormalities associated with ureteral ectopia without the requirement for a general anesthetic/heavy sedation or the administration of intravenous contrast agents.…”

“…Excretory urography has been reported to identify the location of ectopic ureteral orifices correctly in 66–78.2% of cases, 2,7,8 with fluoroscopy and evacuation of rectal contents shown to improve sensitivity 10 . More recently, CT excretory urography (CT) and four‐dimensional CT excretory urography (4D‐CTEU) have been used for the diagnosis of EUs with a reported 73–100% and 97% sensitivity, respectively 10,11,12 . With the advancement of endoscopic technology, cystoscopy has been described as the gold standard for EU diagnosis as it allows the operator to visualize the ureteral orifices directly, with a reported sensitivity of 100%, as well as enabling concurrent laser ablation of intramural EUs 5,8,10 .…”

Bilateral ectopic ureteroceles complicated by a large calculus within the left ureterocele in a dog

“…CTEU has been considered the imaging method of choice for the detection of ectopic ureters in dogs, 8 and in this case, it allowed to establish our final diagnosis of bilateral ectopic ureteroceles and calculus within the left one. Nevertheless, it has been recently reported that four‐dimensional CTEU is slightly superior to CTEU when investigating ureteral ectopia as cause of urinary incontinence, 10 and identification of the ureters is better visualized when the maximum intensity projection is used 11 . The treatment of ureteroceles is directed towards the preservation of renal function, preventing urinary outflow obstruction of both ureters and urinary bladder and maintaining urinary continence.…”

Unilateral extramural ureteral ectopia in a cat: Ultrasonographic and computed tomography findings

“…9,14 In clinical practice, the appropriate diagnostic workup is essential for establishing a correct diagnosis and prognosis and choosing the right treatment. A large number of reports have studied the diagnostic utility of radiographic, 16,22,24,30,33,34 ultrasonographic 22,[33][34][35] and CT studies 22,32,34,36,37 in dogs with urinary incontinence and ureteral ectopia. Studies supporting one diagnostic approach over another in feline patients with ureteral ectopia are unfortunately lacking.…”