A pilot study of [68Ga]Ga-fibroblast activation protein inhibitor-04 PET/CT in renal cell carcinoma.
As a promising positron emission tomography (PET) tracer, [68Ga]Ga-fibroblast activation protein inhibitor-04([68Ga]Ga-FAPI-04) performs better than 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) at diagnosing primary and metastatic lesions in patients with various types of cancer. We investigated the utility of [68Ga]Ga-FAPI-04 PET/CT for the detection of primary and metastatic lesions in renal cell carcinoma (RCC). [18F]FDG PET/CT were used for comparison.
Twenty-two patients with suspected RCC or recurrent RCC were enrolled in our study. Among these patients, 14 were newly diagnosed with RCC, 3 had recurrent RCC, and 5 were excluded from further analysis due to having benign renal tumours. Seventeen patients with RCC underwent [68Ga]Ga-FAPI-04 PET/CT, and 6 of them also received [18F]FDG PET/CT. The positive detection rates were calculated and compared with those in patients who underwent both scans.
Data from 17 patients with RCC (median age: 60.5 years, interquartile range [IQR]: 54-70 years) were evaluated. The positive detection rate of [68Ga]Ga-FAPI-04 PET/CT for RCC was 64.7% (11/17). Lymph node metastases (n = 44), lung metastasis (n = 1), and bone metastasis (n = 1) were detected. Six patients with RCC underwent [68Ga]Ga-FAPI-04 and [18F]FDG PET/CT. [68Ga]Ga-FAPI-04 PET/CT showed a higher positive detection rate than [18F]FDG PET/CT in detecting RCC (83.3% [5/6] vs. 50% [3/6], P = 0.545). Additionally, [68Ga]Ga-FAPI-04 PET/CT has higher SUVmax (3.20 [IQR: 2.91-5.80 vs. 2.71 [IQR: 2.13-3.10], P = 0.116) and tumour-to-background ratio (TBR) values (1.60 [IQR: 1.33-3.67] vs. 0.86 [0.48-1.21], P = 0.028) than [18F]FDG PET/CT.
These findings suggest that [68Ga]Ga-FAPI-04 PET/CT has potential value in RCC diagnosis. Further studies are warranted to validate these results.
Clinical utility of [68Ga]Ga-FAPI-04 in RCC remains unclear, and there are not many similar studies in the literature. We evaluated the role of [68Ga]Ga-FAPI-04 in diagnosing RCC.
Guo C
,Liu Y
,Yang H
,Xia Y
,Li X
,Chen L
,Feng Y
,Zhang Y
,Chen Y
,Huang Z
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Comparisons of Quantitative Parameters of Ga-68-Labelled Fibroblast Activating Protein Inhibitor (FAPI) PET/CT and [(18)F]F-FDG PET/CT in Patients with Liver Malignancies.
To compare quantitative parameters and tumour detection rates of [68 Ga]Ga-FAPI PET/CT with those of dedicated liver PET/MRI and 18F-FDG PET in patients with liver malignancies.
Twenty-seven patients (29 imaging studies) with diagnosed or suspected liver malignancies who underwent [68 Ga]Ga-FAPI-46 PET/CT, liver PET/MRI, and [18F]FDG PET/CT between September 2020 and June 2021 were retrospectively analysed. MRI findings were used as the reference standard for diagnosis.
The 27 patients had a median age of 68 years (interquartile range: 60-74 years; 21 men). Primary intrahepatic tumours were reported in 13 patients (15 imaging studies) with cholangiocarcinoma (CCA) and in 14 patients with hepatocellular carcinoma (HCC). All intrahepatic lesions detectable on MRI were also detected on [68 Ga]Ga-FAPI-46 PET/CT giving a sensitivity of 100% (19/19), whereas the sensitivity of [18F]FDG PET/CT was 58% (11/19). All intrahepatic lesions were detected on [68 Ga]Ga-FAPI-46 PET/CT, on which they showed higher activity (median SUVmax: 15.61 vs. 5.17; P < .001) and higher target-to-background ratio (TBR; median, 15.90 vs. 1.69, P < .001) than on [18F]FDG, especially in patients with CCA (median TBR, 21.08 vs. 1.47, respectively; P < .001). The uptake positivity rate in regional node metastasis was 100% (12/12) on [68 Ga]Ga-FAPI-46 PET/CT compared with 58% (7/12) on [18F]FDG PET/CT. All patients with distant metastasis (100%, 14/14) were detected on both [18F]FDG and [68 Ga]Ga-FAPI-46 PET/CT imaging, although more distant metastatic lesions were detected on [68 Ga]Ga-FAPI-46 PET/CT than on [18F]FDG (96% (42/44) vs. 89% (39/44), respectively).
[68 Ga]Ga-FAPI PET/CT with dedicated liver PET/MRI shows potential for superior detection of hepatic malignancy compared with [18F]FDG PET/CT or MRI alone.
Siripongsatian D
,Promteangtrong C
,Kunawudhi A
,Kiatkittikul P
,Boonkawin N
,Chinnanthachai C
,Jantarato A
,Chotipanich C
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Detection of tumour heterogeneity in patients with advanced, metastatic castration-resistant prostate cancer on [(68)Ga]Ga-/[(18)F]F-PSMA-11/-1007, [(68)Ga]Ga-FAPI-46 and 2-[(18)F]FDG PET/CT: a pilot study.
In metastatic castration-resistant prostate cancer (mCRPC), some patients show low/absent PSMA expression in tumour lesions on positron emission tomography (PET) scans, indicating heterogeneity and heightened risk of non-response to PSMA-RLT (radioligand therapy). Imaging cancer-associated fibroblasts and glucose uptake may further characterise tumour heterogeneity in mCRPC patients. Here, we aimed to evaluate tumour heterogeneity and its potential implications for management in mCRPC patients assessed for PSMA-RLT using [68Ga]Ga-FAPI-46, 2-[18F]FDG and [68Ga]Ga-/[18F]F-PSMA-11/-1007 PET.
Patients with advanced, progressive mCRPC underwent clinical [68Ga]Ga-/[18F]F-PSMA-11/-1007, 2-[18F]FDG and [68Ga]Ga-FAPI-46 PET/CT to evaluate treatment with PSMA-directed RLT. Tumour detection/semiquantitative parameters were compared on a per-lesion/-region basis. Two phenotypes were defined: Criteria for the mixed phenotype were: (a) PSMA-negative findings for lymph node metastases ≥ 2.5 cm, any solid organ metastases ≥ 1.0 cm, or bone metastases with soft tissue component ≥ 1.0 cm, (b) low [68Ga]Ga-/[18F]F-PSMA-11/-1007 uptake and/or (c) balanced tumour uptake of all radioligands. The PSMA-dominant phenotype was assigned if the criteria were not met.
In ten patients, 472 lesions were detected on all imaging modalities (miTNM regions: M1b: 327 (69.3%), M1a: 95 (20.1%), N1: 26 (5.5%), M1c: 18 (3.8%), T: 5 (1.1%) and Tr: 1 (0.2%). [68Ga]Ga-/[18F]F-PSMA-11/-1007 (n = 453 (96.0%)) demonstrates the highest detection rate, followed by [68Ga]Ga-FAPI-46 (n = 268 (56.8%))/2-[18F]FDG (n = 241 (51.1%)). Semiquantitative uptake was highest for [68Ga]Ga-/[18F]F-PSMA-11/-1007 (mean SUVmax (interquartile range): 22.7 (22.5), vs. [68Ga]Ga-FAPI-46 (7.7 (3.7)) and 2-[18F]FDG (6.8 (4.7)). Seven/three patients were retrospectively assigned to the PSMA-dominant/mixed phenotype. Median overall survival was significantly longer for patients who underwent [177Lu]Lu-PSMA-617 RLT and were retrospectively assigned to the PSMA-dominant phenotype (19.7 vs. 9.3 months).
Through whole-body imaging, we identify considerable inter- and intra-patient heterogeneity of mCRPC and potential imaging phenotypes. Regarding uptake and tumour detection, [68Ga]Ga-/[18F]F-PSMA-11/-1007 was superior to [68Ga]Ga-FAPI-46 and 2-[18F]FDG, while the latter two were comparable. Patients who underwent [177Lu]Lu-PSMA-617 RLT based on clinical-decision making had a longer overall survival and could be assigned to the PSMA-dominant phenotype.
Pabst KM
,Mei R
,Lückerath K
,Hadaschik BA
,Kesch C
,Rawitzer J
,Kessler L
,Bodensieck LS
,Hamacher R
,Pomykala KL
,Fanti S
,Herrmann K
,Fendler WP
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Exploring the Potential Value of [ 68 Ga]Ga-FAPI-46 PET/CT for Molecular Assessment of Fibroblast Activation in Interstitial Lung Disease : A Single-Center Pilot Study.
The aim of the study was to evaluate the association of high-resolution computed tomography (HRCT) findings with pulmonary fibrotic activity in the corresponding regions using [ 68 Ga]Ga-fibroblast activation fibroblast inhibitor (FAPI) PET/CT in patients with interstitial lung disease (ILD). Additionally, the potential of [ 68 Ga]Ga-FAPI-46 PET/CT for evaluating the active fibrosis process and 99m Tc-MIBI scintigraphy for assessing the inflammatory process in ILD patients was also assessed.
In this pilot study, 20 ILD patients underwent [ 68 Ga]Ga-FAPI-46 PET/CT and 99m Tc-MIBI SPECT/CT. Additionally, 10 patients without lung or thoracic involvement who were undergoing [ 68 Ga]Ga-FAPI PET/CT for cancer detection were enrolled in the control group. The images were evaluated both visually and semiquantitatively and also compared with HRCT and pulmonary function tests. Multiple quantitative parameters were derived from the lung segments in the PET scan, including SUV max , SUV mean , maximum target-to-liver ratio, mean target-to-liver ratio (TLR mean ), and total lesion FAPI expression for the entire lung, as well as its lobes and zones. Additionally, the maximum Hounsfield unit (HU) and mean HU in HRCT were calculated for the whole lung as well as its lobes and zones. Furthermore, an HRCT fibrosis score (HFS) was defined according to the HRCT findings.
Twenty ILD patients with a mean age of 58.70 (SD, 11.09) years were enrolled. Additionally, 10 control patients were enrolled with a mean age of 57.70 (SD, 15.19) years. Based on visual assessment, the FAPI scan was positive in 12 (60%) patients. Similarly, the MIBI scan was positive in 12 (60%) patients. In the 20 ILD cases, both scans were positive in 6 cases, and both were negative in 2 cases. Six cases showed FAPI-negative and MIBI-positive results, whereas another 6 cases showed FAPI-positive and MIBI-negative results. Comparing the control and ILD patients, there was a significant difference in SUV max , SUV mean , total lesion FAPI expression, TLR mean , maximum HU, and mean HU ( P < 0.05). When comparing HFS with PET-derived parameters in zones, a significant positive correlation was found between HFS and SUV mean , SUV max , maximum target-to-liver ratio, and TLR mean ( P < 0.05). Additionally, a significant difference was noted between FAPI results and HFS ( P = 0.003). An ancillary finding, 9 of 20 (45%) ILD patients showed intense FAPI uptakes in gallbladder, whereas none of the 10 in the control group showed such uptake.
The present study may suggest that combining [ 68 Ga]Ga-FAPI PET/CT and 99m Tc-MIBI SPECT/CT yields an additive effect for evaluating ILD-related fibrosis and inflammatory processes over using either modality alone. Furthermore, it appears that [ 68 Ga]Ga-FAPI PET/CT has the potential to ascertain levels of fibrotic activity from population of resident fibroblasts, active fibroblasts, and scar maturation among ILD patients based on their HRCT patterns.
Bahtouee M
,Jafari E
,Khazaei M
,Aram N
,Amini A
,Jokar N
,Ahmadzadehfar H
,Gholamrezanezhad A
,Assadi M
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