From the Guidelines
Imaging tests that confirm Polycystic Kidney Disease (PKD) include ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI), with MRI being the most sensitive for detecting small cysts 1.
Key Imaging Tests
- Ultrasound: typically the first-line imaging test due to its accessibility, safety, and cost-effectiveness, and can detect cysts as small as 1-2 cm 1.
- Computed Tomography (CT): provides more detailed images and can detect smaller cysts than ultrasound, making them valuable when ultrasound results are inconclusive 1.
- Magnetic Resonance Imaging (MRI): offers the highest sensitivity for detecting small cysts and is excellent for assessing kidney structure and function without radiation exposure, though it's more expensive and less readily available 1.
Diagnosis Criteria
Diagnosis typically requires finding multiple cysts of specific sizes based on age-related criteria. For example, in autosomal dominant PKD, individuals under 30 years need at least two cysts in one or both kidneys, while those over 60 need at least four cysts in each kidney 1. The Mayo Imaging Classification (MIC) can also be used to predict future decline in kidney function and the timing of kidney failure, and is divided into typical (class 1) and atypical (class 2) ADPKD 1.
Recommendations
For people with a positive family history of ADPKD aged 16–40 years, the cutoff of >10 cysts on magnetic resonance imaging (MRI) has been used to diagnose ADPKD, and the cutoff of <5 cysts has been used to exclude ADPKD 1. In cases where the diagnosis is uncertain, genetic testing may be helpful, particularly in cases involving few kidney cysts, variable intrafamilial disease severity, or discordant imaging and glomerular filtration rate 1. It is also recommended to employ the Mayo Imaging Classification (MIC) to predict future decline in kidney function and the timing of kidney failure, which uses height-adjusted total kidney volume, adjusted for age, to stratify people with typical imaging into 5 groups (1A–1E) 1.
From the Research
Imaging Tests for Polycystic Kidney Disease (PKD)
The following imaging tests can confirm Polycystic Kidney Disease (PKD):
- Ultrasonography: used to diagnose PKD in children and adults 2
- Computed Tomography (CT): used to assess renal blood flow and noncystic renal parenchyma 2, 3
- Magnetic Resonance Imaging (MRI): used to measure total kidney volume, assess disease progression, and predict overall prognosis 2, 4, 5
Key Findings
- MRI-derived total kidney volume is a biomarker for assessing ADPKD severity and predicting decline in renal function 4
- Non-contrast-enhanced MRI can be used to assess kidney volume in PKD patients without the need for contrast medium 5
- Non-enhanced MRI is more sensitive than ultrasound in identifying renal cell carcinomas and suspicious lesions in patients with Acquired Cystic Kidney Disease (ACKD) 6