What are the MRI criteria for diagnosing Autosomal Dominant Polycystic Kidney Disease (ADPKD)?

MRI Criteria for Diagnosing ADPKD

For individuals aged 16-40 years with a positive family history of ADPKD, the presence of >10 total kidney cysts on MRI confirms the diagnosis, while <5 total cysts rules out ADPKD. 1

Diagnostic Criteria by Imaging Modality and Age

MRI Criteria

• Ages 16-40 years with positive family history:

  • 10 total kidney cysts: ADPKD confirmed 1

  • <5 total kidney cysts: ADPKD ruled out 1
  • 5-10 cysts: Equivocal result requiring follow-up or genetic testing 1
• Children <15 years: No established MRI-based diagnostic criteria exist 1, 2

Ultrasound Criteria (for comparison)

• Ages 15-39 years: ≥3 total cysts confirms ADPKD; ≤1 cyst rules it out 1, 3
• Ages 40-59 years: ≥2 cysts in each kidney confirms ADPKD; ≤2 cysts total rules it out 1, 3
• Age ≥60 years: ≥4 cysts in each kidney confirms ADPKD 1, 3
• Children <15 years with positive family history: One or more kidney cysts is highly suggestive of ADPKD 1

Important Considerations

Diagnostic Algorithm

1. Start with ultrasound as first-line imaging for screening 1
2. Proceed to MRI when:
   • Ultrasound results are equivocal or atypical 1
   • Additional prognostic information is needed 1
   • Patient is aged 16-40 years with indeterminate ultrasound findings 1, 4

Limitations and Caveats

• MRI criteria apply only to families with PKD1 or PKD2 mutations, not to those with minor gene variants 1
• MRI is more sensitive than ultrasound for detecting kidney cysts, especially in younger adults and teenagers 1, 2, 4
• In a family with a known pathogenic variant, targeted genetic testing for the specific variant is usually sufficient and may be preferable to imaging 1
• High-resolution ultrasound has improved sensitivity (97%) compared to conventional ultrasound (82%) but remains center and operator-dependent 4

Special Situations

• For individuals with incidentally detected kidney cysts but no family history, both kidney MRI and genetic testing may be needed for diagnosis 1
• Genetic testing is particularly helpful in cases with few kidney cysts, variable disease severity within families, discordant imaging and GFR findings, or negative family history 1
• MRI-derived total kidney volume serves as a biomarker for disease severity and can predict decline in renal function using the Mayo Imaging Classification 1, 5

Prognostic Value of MRI

• The Mayo Imaging Classification (MIC) uses height-adjusted total kidney volume measured by MRI to stratify patients with typical imaging into 5 groups (1A-1E), indicating accelerating decline in kidney function 1
• MRI is the preferred modality for measuring total kidney volume accurately, using automated or semi-automated tools 1
• Prognostic information from MIC is valid only for patients with typical imaging findings (class 1) and PKD1 or PKD2 mutations 1