Imaging of fibrogenesis in patients with idiopathic pulmonary fibrosis with cis-4-[(18)F]-Fluoro-L: -proline PET.
OBJECTIVE
Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease for which no single diagnostic modality is able to evaluate the activity of the disease process. Cis-4-(18)F-fluoro-L: -proline ((18)F-proline) was shown in animal studies to be a reliable marker for fibrosis formation. We tested this candidate radioligand for imaging of fibrogenesis in patients with IPF.


METHODS
Five patients with IPF proven by lung biopsy and computed tomography were included. Furthermore, we also included one patient with non-specific interstitial pneumonia (NSIP) and scleroderma and one with NSIP and organising pneumonia. Positron emission tomography (PET) acquisition was performed 1, 2 and 3h after injection of 400MBq (18)F-proline. We scored (18)F-proline activity visually and quantitatively by calculating the activity in the regions of interest over lung, liver and mediastinum.


RESULTS
We found low uptake of (18)F-proline in the lungs of all patients with IPF. The highest uptake was seen at 2h post-injection, with a decline at 3h past injection. The differences in lung uptake between patients were small, except for one patient with NSIP and organising pneumonia who had a slightly higher (18)F-proline uptake. No significant correlations between (18)F-proline uptake and clinical parameters were found.


CONCLUSIONS
Due to the low pulmonary uptake of (18)F-proline in patients with IPF, (18)F-proline does not seem to be a suitable radioligand to evaluate the activity of fibrosis formation in patients with IPF. The low uptake in the lungs of patients with interstitial fibrosis may be explained by the slow nature of fibrogenesis or to the relatively low dose of proline that can be used.
Lavalaye
Jules
J
Department of Nuclear Medicine, St. Antonius Hospital, P.O. Box 2500, 3430 EM, Nieuwegein, The Netherlands. j.lavalaye@antonius.net
Grutters
Jan C
JC
van de Garde
Ewoudt M W
EM
van Buul
Monique M C
MM
van den Bosch
Jules M M
JM
Windhorst
Albert D
AD
Verzijlbergen
Fred J
FJ
D000368:Aged; D005260:Female; D005355:Fibrosis / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000000981:diagnostic imaging / Q000378:metabolism; D049268:Positron-Emission Tomography / Q000379:methods*; D011392:Proline / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014018:Tissue Distribution; D051598:Whole Body Imaging / Q000379:methods
D019275:Radiopharmaceuticals; C431803:fluoro-proline; D011392:Proline