Image analysis: ⁶⁸Ga-FAPI-46 PET derived texture parameters improve the differentiation of malignant and benign...

Pulmonary lesions inconclusive in ¹⁸F-FDG PET/CT are a known clinical problem. Both texture analysis and ⁶⁸Ga-FAPI-46 have shown potential in thoracic oncological problems but their combination has not been assessed yet. This initial analysis aims to evaluate the utility of ⁶⁸Ga-FAPI-46 PET texture parameters to differentiate between lung cancer and benign pulmonary lesions inconclusive in ¹⁸F-FDG PET/CT.

20 histologically confirmed pulmonary lesions (13 lung cancer, 7 benign) in 19 patients were evaluated. All patients underwent an inconclusive ¹⁸F-FDG PET/CT before ⁶⁸Ga-FAPI-46 PET/CT. 64 texture parameters and conventional parameters (SUVs, TBRs) were analyzed. Texture parameters with significant (P < 0.05) differences between lung cancer and benign lesions were detected by the Mann-Whitney U test. Boxplots and a scatter plot matrix were created. Principal component analyses and Spearman correlations were performed. Receiver operating characteristics curves with area under the curve (AUC) values were created for univariable and bivariable logistic regression.

The texture parameters HIST Maximum grey level (AUC = 0.901), HIST Mean (AUC = 0.802), HIST Mode (AUC = 0.835), HIST Range (AUC = 0.901) and GLCM Information correlation 1 (AUC = 0.824) showed significant differences between lung cancer and benign pulmonary lesions. AUC values of conventional parameters (SUVmax, SUVmean, TBR(SUVmax), TBR(SUVmean)) were 0.791, 0.868, 0.802 and 0.857, respectively. Maximum AUC values of bivariable logistic regression were 0.967 and 0.978 for two texture parameters and the combination of conventional and texture parameters, respectively. Correlations between texture parameter pairs were mainly moderate (0.4≤ρ≤0.59). 2/5 texture parameters (HIST Mean, HIST Mode) displayed no very strong correlations (0.8≤ρ≤1.00) to any conventional parameters or lesion volume.

⁶⁸Ga-FAPI-46 PET texture parameters show great potential to differentiate between lung cancer and benign pulmonary lesions inconclusive in ¹⁸F-FDG/PET. Spearman correlations indicate additional information value of texture parameters.