European Journal of Nuclear Medicine and Molecular Imaging

, Volume 33, Issue 5, pp 541–552

The presentation of malignant tumours and pre-malignant lesions incidentally found on PET-CT

Authors

    • Department of Nuclear MedicineTel Aviv Sourasky Medical Center
    • Department of Sackler Faculty of MedicineTel Aviv University
  • Hedva Lerman
    • Department of Nuclear MedicineTel Aviv Sourasky Medical Center
  • Mordechai Gutman
    • Department of Sackler Faculty of MedicineTel Aviv University
    • Department of Surgery “A”Sapir Medical Center
  • Gennady Lievshitz
    • Department of Nuclear MedicineTel Aviv Sourasky Medical Center
  • Limor Zuriel
    • Department of Nuclear MedicineTel Aviv Sourasky Medical Center
  • Aaron Polliack
    • Department of HematologyHadassah University Hospital
  • Moshe Inbar
    • Department of Sackler Faculty of MedicineTel Aviv University
    • Department of OncologyTel Aviv Sourasky Medical Center
  • Ur Metser
    • Department of Nuclear MedicineTel Aviv Sourasky Medical Center
Original article

DOI: 10.1007/s00259-005-0056-4

Cite this article as:
Even-Sapir, E., Lerman, H., Gutman, M. et al. Eur J Nucl Med Mol Imaging (2006) 33: 541. doi:10.1007/s00259-005-0056-4

Abstract

Purpose

The purpose of the study was to determine the general and organ-specific presentation of incidental primary tumours on PET-CT.

Methods

PET-CT reports of 2,360 consecutive patients were reviewed and revealed 156 lesions suspicious for a new unexpected malignancy, in 151 patients. One hundred and twenty of these lesions, in 115 patients, were further assessed, by biopsy (n=84 patients) or by clinical and imaging follow-up (n=31 patients) for a mean of 17±4 months (range 12–25 months).

Results

Forty-four unexpected malignancies were found in 41 of the study patients (1.7%). Twenty-seven of the 44 incidental tumours were identified on the basis of their location, which was uncommon for metastasis of the known malignancy. Eight were detected as a result of either the difference in FDG avidity of the known malignancy and the incidental lesion or the presence of an incidental non-FDG-avid mass on the CT part of the study. Four tumours were synchronous carcinomas in patients with known colorectal malignancy, three were identified by virtue of the discordant response to treatment compared with the known primary tumour and two were detected as new sites of disease after a prolonged disease-free period. There was organ variability in the positive predictive values (PPV) of PET-CT findings for incidental primary malignancy or pre-malignant lesions: 62% for colonic lesions, 54% for lung lesions and 24% for thyroid lesions.

Conclusion

Incidental primary tumours may be identified on PET-CT based on their location, FDG avidity, response to therapy and time of appearance. The PET and CT parts of the study appear to complement each other and assist in identification of these incidental tumours.

Keywords

PET/CTSynchronousMalignancyFDG

Copyright information

© Springer-Verlag 2006