RT Journal Article
SR Electronic
T1 Diagnostic Potential of Supplemental Static and Dynamic <sup>68</sup>Ga-FAPI-46 PET for Primary <sup>18</sup>F-FDG–Negative Pulmonary Lesions
JF Journal of Nuclear Medicine
JO J Nucl Med
FD Society of Nuclear Medicine
SP jnumed.123.267103
DO 10.2967/jnumed.123.267103
A1 Röhrich, Manuel
A1 Daum, Johanna
A1 Gutjahr, Ewgenija
A1 Spektor, Anna-Maria
A1 Glatting, Frederik M.
A1 Sahin, Yasemin Aylin
A1 Buchholz, Hans Georg
A1 Hoppner, Jorge
A1 Schroeter, Cathrin
A1 Mavriopoulou, Eleni
A1 Schlamp, Kai
A1 Grott, Matthias
A1 Eichhorn, Florian
A1 Heußel, Claus Peter
A1 Kauczor, Hans Ulrich
A1 Kreuter, Michael
A1 Giesel, Frederik
A1 Schreckenberger, Mathias
A1 Winter, Hauke
A1 Haberkorn, Uwe
YR 2024
UL http://jnm.snmjournals.org/content/early/2024/04/11/jnumed.123.267103.abstract
AB PET using 68Ga-labeled fibroblast activation protein (FAP) inhibitors (FAPIs) holds high potential for diagnostic imaging of various malignancies, including lung cancer (LC). However, 18F-FDG PET is still the clinical gold standard for LC imaging. Several subtypes of LC, especially lepidic LC, are frequently 18F-FDG PET–negative, which markedly hampers the assessment of single pulmonary lesions suggestive of LC. Here, we evaluated the diagnostic potential of static and dynamic 68Ga-FAPI-46 PET in the 18F-FDG–negative pulmonary lesions of 19 patients who underwent surgery or biopsy for histologic diagnosis after PET imaging. For target validation, FAP expression in lepidic LC was confirmed by FAP immunohistochemistry. Methods: Hematoxylin and eosin staining and FAP immunohistochemistry of 24 tissue sections of lepidic LC from the local tissue bank were performed and analyzed visually. Clinically, 19 patients underwent static and dynamic 68Ga-FAPI-46 PET in addition to 18F-FDG PET based on individual clinical indications. Static PET data of both examinations were analyzed by determining SUVmax, SUVmean, and tumor-to-background ratio (TBR) against the blood pool, as well as relative parameters (68Ga-FAPI-46 in relation to18F-FDG), of histologically confirmed LC and benign lesions. Time–activity curves and dynamic parameters (time to peak, slope, k1, k2, k3, and k4) were extracted from dynamic 68Ga-FAPI-46 PET data. The sensitivity and specificity of all parameters were analyzed by calculating receiver-operating-characteristic curves. Results: FAP immunohistochemistry confirmed the presence of strongly FAP-positive cancer-associated fibroblasts in lepidic LC. LC showed markedly elevated 68Ga-FAPI-46 uptake, higher TBRs, and higher 68Ga-FAPI-46–to–18F-FDG ratios for all parameters than did benign pulmonary lesions. Dynamic imaging analysis revealed differential time–activity curves for LC and benign pulmonary lesions: initially increasing time–activity curves with a decent slope were typical of LC, and steadily decreasing time–activity curve indicated benign pulmonary lesions, as was reflected by a significantly increased time to peak and significantly smaller absolute values of the slope for LC. Relative 68Ga-FAPI-46–to–18F-FDG ratios regarding SUVmax and TBR showed the highest sensitivity and specificity for the discrimination of LC from benign pulmonary lesions. Conclusion: 68Ga-FAPI-46 PET is a powerful new tool for the assessment of single 18F-FDG–negative pulmonary lesions and may optimize patient stratification in this clinical setting.