[(124)I]FIAU: Human dosimetry and infection imaging in patients with suspected prosthetic joint infection

Nucl Med Biol. 2016 May;43(5):273-9. doi: 10.1016/j.nucmedbio.2016.01.004. Epub 2016 Feb 2.


Introduction: Fialuridine (FIAU) is a nucleoside analog that is a substrate for bacterial thymidine kinase (TK). Once phosphorylated by TK, [(124)I]FIAU becomes trapped within bacteria and can be detected with positron emission tomography/computed tomography (PET/CT). [(124)I]FIAU PET/CT has been shown to detect bacteria in patients with musculoskeletal bacterial infections. Accurate diagnosis of prosthetic joint infections (PJIs) has proven challenging because of the lack of a well-validated reference. In the current study, we assessed biodistribution and dosimetry of [(124)I]FIAU, and investigated whether [(124)I]FIAU PET/CT can diagnose PJIs with acceptable accuracy.

Methods: To assess biodistribution and dosimetry, six subjects with suspected hip or knee PJI and six healthy subjects underwent serial PET/CT after being dosed with 74MBq (2mCi) [(124)I]FIAU intravenously (IV). Estimated radiation doses were calculated with the OLINDA/EXM software. To determine accuracy of [(124)I]FIAU, 22 subjects with suspected hip or knee PJI were scanned at 2-6 and 24-30h post IV injection of 185MBq (5mCi) [(124)I]FIAU. Images were interpreted by a single reader blinded to clinical information. Representative cases were reviewed by 3 additional readers. The utility of [(124)I]FIAU to detect PJIs was assessed based on the correlation of the patient's infection status with imaging results as determined by an independent adjudication board (IAB).

Results: The kidney, liver, spleen, and urinary bladder received the highest radiation doses of [(124)I]FIAU. The effective dose was 0.16 to 0.20mSv/MBq and doses to most organs ranged from 0.11 to 0.76mGy/MBq. PET image quality obtained from PJI patients was confounded by metal artifacts from the prostheses and pronounced FIAU uptake in muscle. Consequently, a correlation with infection status and imaging results could not be established.

Conclusions: [(124)I]FIAU was well-tolerated in healthy volunteers and subjects with suspected PJI, and had acceptable dosimetry. However, the utility of [(124)I]FIAU for the clinical detection of PJIs is limited by poor image quality and low specificity.

Keywords: Diagnosis; FIAU; PET/CT; Prosthetic joint infection.

Publication types

  • Clinical Trial, Phase I
  • Clinical Trial, Phase II

MeSH terms

  • Adult
  • Arabinofuranosyluracil / adverse effects
  • Arabinofuranosyluracil / analogs & derivatives*
  • Arabinofuranosyluracil / pharmacokinetics
  • Female
  • Humans
  • Joint Diseases / diagnostic imaging*
  • Joint Diseases / metabolism
  • Male
  • Positron Emission Tomography Computed Tomography / adverse effects
  • Positron Emission Tomography Computed Tomography / methods*
  • Prosthesis-Related Infections / diagnostic imaging*
  • Prosthesis-Related Infections / metabolism
  • Radiometry
  • Safety
  • Tissue Distribution


  • Arabinofuranosyluracil
  • fialuridine