ABSTRACT
Objective:
To compare the clinical utility of 18F-
fibroblast activating
protein inhibitor (FAPI)-42 and 18F-fluorodeoxyglucose (FDG)
PET/CT imaging in newly diagnosed
lung cancer patients.
Methods:
From May 2020 to September 2021, the images of 43
lung cancer patients (32
males, 11
females, age 37-80 years)
who pathologically confirmed and received
18F-FDG and 18F-FAPI-42
PET/CT within 2 weeks in the First Affiliated
Hospital of Guangzhou Medical
University were prospectively analyzed. The maximum standardized uptake value (SUV max) of
18F-FDG and 18F-FAPI-42 and the number of lesions detected by 2 imaging
methods were compared by using paired t test and Wilcoxon rank sum test.
Results:
The 43 newly diagnosed
lung cancer patients included 35
adenocarcinoma, 2
squamous cell carcinoma, 4
small cell lung cancer, and 2 high-grade
neuroendocrine tumors. 18F-FAPI-42 had a very high
tumor uptake (SUV max 12.24±3.97) and lesion
detection rate (positive rate 100%(37/37)) in primary
lung adenocarcinoma and
squamous cell carcinoma. The uptake of 18F-FAPI-42 in
lymph node (10.13±5.43),
pleura (6.75(4.96, 8.58)) and
bone lesion (7.18(4.33, 9.66)) were significantly higher than those of
18F-FDG (6.35±3.30, 2.69(1.81, 5.00), 4.38(2.96, 6.36); t=12.19, z values 5.47, 5.79, all P<0.001). In
lung adenocarcinoma and
squamous cell carcinoma, although the uptake of 18F-FAPI-42 in
brain metastases was significantly lower than that of
18F-FDG (0.72(0.15, 1.82) vs 6.53(4.65, 9.34); z=6.42, P<0.001), the
tumor/background (T/B) ratio was significantly higher than that of
18F-FDG (3.54(1.15, 14.88) vs 0.96(0.77, 1.04); z=6.05, P<0.001). In
lung adenocarcinoma and
squamous cell carcinoma, the number of lesions detected by 18F-FAPI-42
PET/CT was significantly more than that of
18F-FDG (
lymph node 6.0(2.3, 11.5) vs 4.5(2.0, 10.8);
brain 2.0(1.0, 3.0) vs 0.0(0.0, 0.0);
pleura 6.0(2.8, 10.0) vs 4.0(0.8, 5.5); z values 2.16, 3.10, 2.04, all P<0.05). However, in high-grade
neuroendocrine tumors and
small cell lung cancer, the SUV max of 18F-FAPI-42 in primary lesions (8.05±2.60),
lymph node lesions (5.98±2.21) and
brain lesions (0.44(0.13, 0.82)) were lower than those of
18F-FDG (16.28±5.17, 12.30±5.47, 4.94(4.84, 6.25); t values 3.58, 7.52, z=3.06, all P<0.05).
Conclusions:
In
lung adenocarcinoma and
squamous cell carcinoma, 18F-FAPI-42 has a very high
tumor uptake and lesion
detection rate in primary
tumor. In addition, compared with
18F-FDG PET/CT, 18F-FAPI-42
PET/CT shows clearer
tumor contours and more lesions. Therefore, 18F-FAPI-42 is more suitable for preliminary staging of
lung adenocarcinoma and
squamous cell carcinoma than
18F-FDG, while the opposite is true in
small cell lung cancer and high-grade
neuroendocrine tumors.