Assessment of the relation between pelvicalyceal dilatation in ultrasound and features of obstructive uropathy in dynamic renal scintigraphy

Abstract

BACKGROUND: Ultrasound is the first-line imaging in the diagnostics of the urinary system. It provides valuable morphological information, but its usefulness in assessment of the function of renal parenchyma is limited. Dynamic renal scintigraphy provides much more accurate information about parenchymal function of kidneys and urinary outflow. The aim of the study was to establish morphological ultrasound criteria for high likelihood of obstructive uropathy.

MATERIAL AND METHODS: 59 patients (38 women, 21 men, between 18 and 82 years old, average age 50) with the pelvis dilatation > 10 mm in one or both kidneys newly diagnosed in ultrasound, without earlier history of kidney and urinary tract diseases or renal surgery. A total of 79 kidneys were included in the study.

Ultrasound and dynamic renal scintigraphy were performed on the same day. In ultrasound, maximum anteroposterior diameter of the renal pelvis (mAPD) and anteroposterior pelvic diameter at hilum (hAPD) were obtained. The ratio of total pelvicalyceal area to the whole kidney area (%PCS) was also calculated. Uropathy was determined by the positive diuretic test in renal scintigraphy performed using 111 MBq of 99mTc-EC.

RESULTS: In dynamic renal scintigraphy, features of uropathy were found in 18 out of 79 kidneys (23%). Optimal thresholds for detection of obstructive uropathy for measured ultrasound parameters were determined based on the ROC curves: mAPD ≥ 23 mm (sensitivity 94%, specificity 76%, accuracy 80%, AUROC 0.91) hAPD ≥ 20 mm (sensitivity 78%, specificity 87%, accuracy 85%, AUROC 0.82) PCA/WKA ≥ 22% (sensitivity 83%, specificity 74%, accuracy 76%, AUROC 0.85).

CONCLUSIONS: Determined thresholds of parameters measuring pelvicalyceal dilatation in ultrasound, including the easiest one to obtain in routine diagnostics — mADP, provide satisfactory effectiveness in isolating kidneys with high likelihood of obstructive uropathy. Their application can optimize the selection of patients for further kidney diagnostic imaging (dynamic renal scintigrapy or urography).