Objective: The objective of this study was to assess the diagnostic value of attenuation measurements of the kidney on unenhanced helical CT in patients with obstructive ureterolithiasis.

Materials And Methods: Consecutive unenhanced helical CT scans of patients referred for acute unilateral renal colic were retrospectively reviewed. Patients with CT evidence of other urinary system diseases were excluded. Included scans (n = 145) were assessed for ureteral stone and secondary signs of obstruction such as unilateral collecting system or ureteral dilatation, perinephric stranding, and periureteral edema. Renal attenuation in Hounsfield units was measured in the upper, middle, and lower portions of the parenchyma, and a mean value was determined for each kidney.

Results: Ureteral stones were present in 76 patients. Renal attenuation on the side with lithiasis was lower than on the opposite kidney: 27.2 +/- 3.9 H vs 32.6 +/- 3.4 H (p < 0.001). Attenuation differences between kidneys were higher for patients with ureterolithiasis: 5.4 +/- 3.2 H (range, -3.3 to 13.0 H) versus 1.2 +/- 1.0 H (range, 0-4.7 H) (p < 0.001). An attenuation difference between kidneys greater than or equal to 5.0 H had 61% sensitivity, 100% specificity, 100% positive predictive value, 69% negative predictive value, and 79% accuracy for diagnosis of ureteral lithiasis.

Conclusion: Attenuation difference between kidneys greater than or equal to 5.0 H was a valuable sign and had diagnostic performance similar to other secondary signs of obstructive ureterolithiasis. Furthermore, attenuation difference had the advantage of being an objective, measurement-based indicator.

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http://dx.doi.org/10.2214/ajr.182.5.1821251DOI Listing

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  • - The study aimed to compare the outcomes and complications of elective ureteroscopy performed within one week versus more than one week after renal colic caused by ureteral stones larger than 6 mm, involving 338 patients.
  • - Results showed that patients in the early group (within one week) had a higher rate of stone residue (5.4% vs. 1.1%) and required repeat procedures more often (4.8% vs. 0.6%), indicating better outcomes for the late group.
  • - Postoperative complications were significantly lower in the late group (16.2% vs. 32.1%), suggesting that delaying ureteroscopy beyond one week could lead to better overall recovery and fewer
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