Relationship between retention index in dual-phase (18)F-FDG PET, and hexokinase-II and glucose transporter-1 expression in pancreatic cancer.
Recently, some studies have shown that delayed scanning with (18)F-FDG PET may help to differentiate malignant from benign pancreatic lesions. However, no study has evaluated the relationship between temporal changes in (18)F-FDG uptake and expression of hexokinase or glucose transporter.


METHODS
Twenty-one consecutive patients with pancreatic cancer were studied preoperatively by dual-phase (18)F-FDG PET, performed 1 and 2 h after injection of (18)F-FDG. The standardized uptake value (SUV) of the pancreatic cancer was determined, and the retention index (RI) (%) was calculated by subtracting the SUV at 1 h (SUV1) from the SUV at 2 h (SUV2) and dividing by SUV1. The percentages of cells strongly expressing hexokinase type-II (HK-II) and glucose transporter-1 (GLUT-1) were scored on a 5-point scale (1 = 0%-20%, 2 = 20%-40%, 3 = 40%-60%, 4 = 60%-80%, 5 = 80%-100%) by visual analysis of immunohistochemical staining of paraffin sections from the tumor specimens using anti-HK-II and anti-GLUT-1 antibody (HK-index and G-index, respectively).


RESULTS
SUV2 (mean +/- SD, 5.7 +/- 2.6) was higher than SUV1 (5.1 +/- 2.1), with an RI of 8.5 +/- 11.0. Four cases of cancer, in which SUV2 showed a decline from SUV1, showed a low HK-index (1.8 +/- 1.1), whereas 4 cases with an RI of > or =20 and 13 cases with an intermediate RI (0-20) showed significantly higher HK-indices (4.3 +/- 0.7 and 3.1 +/- 1.5, respectively; P < 0.05). RI showed a positive correlation with HK-index, with an R(2) of 0.27 (P < 0.05), but no significant correlation with the G-index. SUV1 showed no relationship with the HK-index but showed a weak positive correlation with the G-index, with an R(2) of 0.05 (P = 0.055).


CONCLUSIONS
These preliminary findings suggest that the RI obtained from dual-phase (18)F-FDG PET can predict HK-II expression and that the SUV (at 1 h) has a positive correlation with GLUT-1 expression but not with HK-II expression.
Higashi
Tatsuya
T
Department of Nuclear Medicine and Diagnostic Imaging, Graduate School of Medicine, Kyoto University, Kyoto, Japan. higashi@kuhp.kyoto-u.ac.jp
Saga
Tsuneo
T
Nakamoto
Yuji
Y
Ishimori
Takayoshi
T
Mamede
Marcelo H
MH
Wada
Michihiko
M
Doi
Ryuichiro
R
Hosotani
Ryo
R
Imamura
Masayuki
M
Konishi
Junji
J
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018282:Cystadenocarcinoma, Mucinous / Q000000981:diagnostic imaging / Q000378:metabolism; D005260:Female; D019788:Fluorodeoxyglucose F18; D051272:Glucose Transporter Type 1; D006593:Hexokinase / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism*; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014055:Tomography, Emission-Computed
D051272:Glucose Transporter Type 1; D009004:Monosaccharide Transport Proteins; D019275:Radiopharmaceuticals; C495677:SLC2A1 protein, human; D019788:Fluorodeoxyglucose F18; D006593:Hexokinase