Positron emission tomography/magnetic resonance imaging for the diagnosis and differentiation of pancreatic tumors

18F-FDG PET/CT metabolic parameters can semi-quantitatively evaluate the nature of the heart and pericardial masses: a retrospective study

The objective of this study was to evaluate semi-quantitatively the diagnostic performance of PET/CT metabolic parameters in differentiating benign or malignant cardiac or pericardial masses. A total of forty-one patients with newly diagnosed cardiac/pericardial masses who underwent 18F-FDG PET/CT were recruited. PET/CT metabolic parameters including the maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), total lesion glycolysis (TLG), tumor metabolic volume (MTV), the maximum tumor-to-mediastinal background ratio (TMR) and the maximum tumor-to-liver background ratio (TLR) is measured or calculated to evaluate the benign or malignant nature of cardiac/pericardial masses. Compared with benign cardiac/pericardial lesions, cardiac/pericardial malignancies had higher SUVmax, SUVmean, TLG, MTV, TMR, and TLR. All these PET/CT metabolic parameters showed high diagnostic performance in semi-quantitative evaluation of benign or malignant cardiac or pericardial masses, and SUVmean and MTV had the highest diagnostic accuracy. Therefore, PET/CT metabolic parameters can semi-quantitatively evaluate the benign or malignant cardiac/pericardial masses.

The Performance Comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for the Identification of Pancreatic Neoplasms

PURPOSE

To determine the optimal imaging tool for clinical evaluation of pancreatic neoplasm by comparing the performance of ¹⁸F-FDG PET/MRI and PET/CT.

PROCEDURES

Patients with suspected pancreatic neoplasms underwent PET/MRI and PET/CT in the same day prior to resection or endoscopic ultrasound-guided fine-needle aspiration. Histology served as the golden standard of lesion classification. Visual assessment on lesion type and lesion malignancy via PET/MRI and PET/CT images was compared. Standard uptake values (SUVs) of PET images from the two scanners were measured and their correlations were further evaluated.

RESULTS

Thirty-nine patients were included for the final analysis. In visual assessment, we found MRI achieved better performance than CT in differentiating solid and cystic neoplasms, with accuracy of 100% vs. 87%, respectively. In visual malignancy diagnosis, the accuracy of PET/CT was 92.3% for overall lesions and 90.9% for cysts, while the accuracy of PET/MRI was 92.3% and 86.4%, respectively. Besides, semi-quantitative analysis achieved better specificity than visual assessment for both hybrid modalities (100% vs. 87.5% for PET/CT; 100% vs. 81.5% for PET/MR). Furthermore, strong correlation of SUV was found between PET/CT and PET/MRI, with Pearson's correlation coefficients > 0.82.

CONCLUSIONS

In this study, we found PET/MRI and PET/CT, both using ¹⁸F-FDG as tracer, had comparable overall performance in identification of pancreatic neoplasms. Interestingly, for patients who had suspected pancreatic neoplasm but invisible FDG uptake, PET/MRI had shown exceptionally better performance, probably because MR images could detect tiny abnormal structures to improve diagnosis.