Does PET SUV Harmonization Affect PERCIST Response Classification?
Pre- and posttreatment PET comparative scans should ideally be obtained with identical acquisition and processing, but this is often impractical. The degree to which differing protocols affect PERCIST classification is unclear. This study evaluates the consistency of PERCIST classification across different reconstruction algorithms and whether a proprietary software tool can harmonize SUV estimation sufficiently to provide consistent response classification.


METHODS
Eighty-six patients with non-small cell lung cancer, colorectal liver metastases, or metastatic melanoma who were scanned for therapy monitoring purposes were prospectively recruited in this multicenter trial. Pre- and posttreatment PET scans were acquired in protocols compliant with the Society of Nuclear Medicine and Molecular Imaging and the European Association of Nuclear Medicine (EANM) acquisition guidelines and were reconstructed with a point spread function (PSF) or PSF + time-of-flight (TOF) for optimal tumor detection and also with standardized ordered-subset expectation maximization (OSEM) known to fulfill EANM harmonizing standards. After reconstruction, a proprietary software solution was applied to the PSF ± TOF data (PSF ± TOF.EQ) to harmonize SUVs with the OSEM values. The impact of differing reconstructions on PERCIST classification was evaluated.


RESULTS
For the OSEMPET1/OSEMPET2(OSEM reconstruction for pre- and posttherapeutic PET, respectively) scenario, which was taken as the reference standard, the change in SUL was -41% ± 25 and +56% ± 62 in the groups of tumors showing a decrease and an increase in18F-FDG uptake, respectively. The use of PSF reconstruction affected classification of tumor response. For example, taking the PSF ± TOFPET1/OSEMPET2scenario increased the apparent reduction in SUL in responding tumors (-48% ± 22) but reduced the apparent increase in SUL in progressing tumors (+37% ± 43), as compared with the OSEMPET1/OSEMPET2scenario. As a result, variation in reconstruction methodology (PSF ± TOFPET1/OSEMPET2or OSEMPET1/PSF ± TOFPET2) led to 13 of 86 (15%) and 17 of 86 (20%) PERCIST classification discordances, respectively. Agreement was better for these scenarios with application of the propriety filter, with κ values of 1 and 0.95 compared with 0.79 and 0.72, respectively.


CONCLUSIONS
Reconstruction algorithm-dependent variability in PERCIST classification is a significant issue but can be overcome by harmonizing SULs using a proprietary software tool.
Nuclear Medicine Department, François Baclesse Cancer Centre, Caen, France.
Elske
E
Quak
Nuclear Medicine Department and EA 3878 IFR 148, University Hospital, Brest, France.
Pierre-Yves
PY
Le Roux
Nuclear Medicine Department, University Hospital, Caen, France.|Normandy University, Caen, France.|INSERM 1199, Caen University, Caen, France.
Charline
C
Lasnon
Nuclear Medicine Department and EA 3878 IFR 148, University Hospital, Brest, France.
Philippe
P
Robin
Cancer Imaging, Peter MacCallum Cancer Institute, East Melbourne, Australia; and.
Michael S
MS
Hofman
Nuclear Medicine Department and EA 3878 IFR 148, University Hospital, Brest, France.
David
D
Bourhis
Cancer Imaging, Peter MacCallum Cancer Institute, East Melbourne, Australia; and.
Jason
J
Callahan
Cancer Imaging, Peter MacCallum Cancer Institute, East Melbourne, Australia; and.
David S
DS
Binns
Nuclear Medicine Department, University Hospital, Caen, France.
Cédric
C
Desmonts
Nuclear Medicine Department and EA 3878 IFR 148, University Hospital, Brest, France.
Pierre-Yves
PY
Salaun
Cancer Imaging, Peter MacCallum Cancer Institute, East Melbourne, Australia; and.|The Sir Peter MacCallum Department of Oncology, The University of Melbourne, Melbourne, Australia.
Rodney J
RJ
Hicks
Nuclear Medicine Department, University Hospital, Caen, France aide-n@chu-caen.fr.|Normandy University, Caen, France.|INSERM 1199, Caen University, Caen, France.
Nicolas
N
Aide
D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D005602:France; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000592:standards; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000628:therapy*; D017063:Outcome Assessment, Health Care / Q000592:standards* / Q000706:statistics & numerical data; D049268:Positron-Emission Tomography / Q000592:standards* / Q000706:statistics & numerical data; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
18F-FDG; PERCIST; PET; harmonization; therapy response