Ultrasound Kidney Length (US-KL)

US-KL alone can be used to determine whether there is risk of rapid disease progression in ADPKD.*1

MRI is the recommended imaging modality for the most accurate and reproducible measurement of kidney length, kidney cyst burden, and TKV. As such, MRI/CT-calculated TKV is a strong predictor of future renal insufficiency in ADPKD. However, US-measured KL is a useful surrogate when MRI/CT-calculated TKV is not feasible.1

US-measured predictor of rapid progression KL > 16.5 cm in patients less than 45 years old

when rapid progression is defined as CKD stage 3 development within 8 years1,2

Kidney Length > 16.5 cm
Limitations
  • In data analysis, KL was not normalized for height, which is an important variable.*2
  • US-measured KL is less accurate with larger kidneys.1
  • US measurements are operator-dependent and lack precision and accuracy for detecting short-term changes in kidney volume and increase the risk of misclassifying ADPKD progression.1,3,4
  • Young patients with lengths < 16.5 cm may still have rapidly progressing disease.3
  • Atypical patients with slow progression may have lengths > 16.5 cm.3

*Based on data analysis comparing baseline US and MRI KL measurements from the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease (CRISP)1

ADPKD=autosomal dominant polycystic kidney disease; MRI=magnetic resonance imaging; TKV=total kidney volume; CT=computed tomography; CKD=chronic kidney disease.

References:

1. Bhutani H, et al. A comparison of ultrasound and magnetic resonance imaging shows that kidney length predicts chronic kidney disease in autosomal dominant polycystic kidney disease. Kidney Int. 2015;88:146-151.

2. Gansevoort RT, et al. Nephrol Dial Transplant. 2016;31:337-348.

3. Chebib FT, et al. J Am Soc Nephrol. 2018;29(10):2458-2470.

4. Magistroni R, et al. A review of the imaging techniques for measuring kidney and cyst volume in establishing autosomal dominant polycystic kidney disease progression. Am J Nephrol. 2018;48:67-78.