Standardized uptake value differences between primary and metastatic lesions in ¹⁸F-FDG PET/CT of patients with lung cancer.
BACKGROUND
FDG-PET/CT is a robust tool for staging of lung cancer, but the differences in FDG uptake between primary and metastatic lesions have not yet been well described.


OBJECTIVE
To define the potential range of standardized uptake value (SUV) differences between primary and metastatic lesions in lung cancer patients and to identify the factors responsible for these differences.


METHODS
FDG-PET/CT images of 75 lung cancers with 296 metastases were analyzed retrospectively. Histological types, primary locations, and metastatic sites were recorded. The average and maximum SUV (SUVavg, SUVmax) of each primary tumor and metastasis were measured, and the ratio of metastatic SUVs to primary SUVs (M/Pavg, M/Pmax), its difference from 100% (diff-M/Pavg, diff-M/Pmax), the ratio of ROI area of metastatic to primary lesions (ROI-M/P), and its difference from 100% (diff-ROI-M/P) were calculated.


RESULTS
M/Pavg was in the range of 35.9-224.6% (mean ± SD: 97.9% ± 35.9%), while M/Pmax was in the range of 24.8-286.7% (98.1% ± 45.3%). Furthermore, values were in the range of 50-200% for M/Pavg in 280/296 lesions (94.6%) and for M/Pmax in 255/296 lesions (86.1%). M/Pavg and M/Pmax showed significant linear correlations with ROI-M/P (r = 0.62, 0.64, respectively). Multivariate analysis showed that diff-ROI-M/P had the greatest effect on diff-M/Pavg and diff-M/Pmax.


CONCLUSIONS
The SUVs of most metastatic lesions ranged from half to double those of primaries in lung cancer patients. When the SUV of a suspected metastasis is beyond the range of half to double that of the primary lung cancer, other non-metastatic lesions should be considered, while taking ROI size into account.
Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan nkosaka@u-fukui.ac.jp.
Nobuyuki
N
Kosaka
Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Tatsuro
T
Tsuchida
Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Kazunobu
K
Tsuji
Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Kazuhiro
K
Shimizu
Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan.
Hirohiko
H
Kimura
D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000378:metabolism*; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Fluorodeoxyglucose (FDG); lung cancer; metastasis; positron emission tomography (PET); standardized uptake value (SUV)