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Kidney Week

Abstract: PO1584

The Use of a Visual Four-Score Scale Improves the Yield of 18F-FDG PET-CT Imaging in the Diagnosis of Cyst Infection in Patients with Autosomal Dominant Polycystic Kidney Disease

Session Information

Category: Genetic Diseases of the Kidneys

  • 1001 Genetic Diseases of the Kidneys: Cystic

Authors

  • Jouret, Francois, Universite de Liege, Liege, Belgium
  • Neuville, Marie, Universite de Liege, Liege, Belgium
  • Lovinfosse, Pierre, Universite de Liege, Liege, Belgium
  • Jadoul, Alexandre, Universite de Liege, Liege, Belgium
  • Thys, Marie, Universite de Liege, Liege, Belgium
  • Seidel, Laurence, Universite de Liege, Liege, Belgium
  • Hustinx, Roland, Universite de Liege, Liege, Belgium
Background

[18F]FDG PET/CT proved useful in the diagnosis of renal and hepatic cyst infection (CyI) in patients with autosomal dominant polycystic kidney disease (ADPKD). However, the definition of CyI by [18F]FDG PET/CT is subjective. Here, we infer a diagnostic threshold of [18F]FDG uptake in case of CyI based on a visual 4-point scale.

Methods

All ADPKD patients who were hospitalized between January 2007 and March 2019 for suspected CyI and who underwent an [18F]FDG PET/CT were retrospectively identified. CyI was defined upon 5 concomitant criteria: (i) fever ≥38°C; (ii) abdominal pain; (iii) peak plasma C-reactive protein levels ≥70 mg/L; (iv) no other cause of inflammation; and (v) favorable outcomes after antibiotics for ≥21 days. First, all [18F]FDG PET/CT images were qualitatively interpreted by 2 blinded board-certified physicians in nuclear medicine. CyI was diagnosed in case of (i) homogeneous or (ii) heterogeneous [18F]FDG accumulation in cyst wall, or (iii) diffuse [18F]FDG accumulation within the cyst. Next, the uptake of [18F]FDG of the suspected CyI was scored in comparison to blood pool and liver activities. An accumulation of [18F]FDG around the cyst equivalent or inferior to the blood pool was scored as 1. If it was superior to the blood pool but inferior or equal to the hepatic [18F]FDG background, it was scored as 2. If it was slightly superior to the liver, it was scored as 3. If it was largely superior to the hepatic [18F]FDG activity, it was scored as 4.

Results

Sixty [18F]FDG PET/CT (man/woman ratio of 54.1%) were performed for suspected CyI in 38 ADPKD patients: 29 episodes met the gold-standard criteria for CyI. The visual assessment of PET/CT images reached a sensitivity of 73.1% and a specificity of 70.6%. The pattern of [18F]FDG accumulation around or within the suspect cyst was not discriminant. By contrast, the 4-point scale improved the diagnostic yield (specificity of 85.3%), with a diagnostic threshold of [18F]FDG uptake ≥3, i.e. higher than the hepatic background.

Conclusion

[18F]FDG PET-CT imaging helps in the diagnosis of CyI in ADPKD patients, and the use of a 4-point scoring of [18F]FDG uptake improves its yield, with positive and negative predictive values of 78.3% and 78.4% respectively.