Uptake changes on the whole-body dynamic18F-FDG PET may assess tissue characterization. Comparison with the conventional delayed scan

• Published in: The Journal of nuclear medicine (1978) Vol. 60
• Main Authors: Nishimura, Motoki, Tamaki, Nagara, Matsushima, Shigenori, Yamada, Sachimi, Nii, Takeshi, Domoto, Hiroshi, Yamada, Kei
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01.05.2019
• Subjects: Benign; Biopsy; Diagnostic systems; Fluorine isotopes; Lesions; Medical imaging; Positron emission; Positron emission tomography; Skin cancer; Tomography
• ISSN: 0161-5505; 1535-5667

Objectives: 18F-fluorodeoxyglucose (18F-FDG) uptake changes with dual point positron emission tomography (PET) scan (90-120 min vs. 60 min) have been used for charactering FDG positive lesions. A new PET system permits whole-body dynamic acquisition within a short interval. We analyzed uptake changes in 12 minutes in order to assess lesion characterization with the dynamic PET in comparison with the conventional delayed scan. Methods: 52 patients received 3 min x 4 whole-body dynamic PET scans starting at 60 min after 3.7 MBq/kg of FDG administration using Biograph Horizon Flow edition. The mean count changes in the 12 min were analyzed in 46 lesions in comparison with those on the delayed scan obtained at 90-120 min. In addition, the conventional FDG whole-body images were created by summation of the 4 dynamic images and compared with those on the delayed scan.The mean count increases in each lesion were semi-quantitatively analyzed by the 12 min dynamic scan at 60 minutes to compare with those at the 90-120 min delayed scan. Results: 46 lesions with abnormal FDG uptake were analyzed, including 26 malignant lesions and 20 benign lesions on histological and/or clinical follow-up studies. Of 26 malignant lesions, an increase in FDG uptake was observed in 24 lesions (92%) on the whole-body dynamic scan, and 26 lesions (100%) on the delayed scan. Of 20 of the benign lesions, an increase in FDG uptake was seen in 18 lesions (90%) on the whole-body dynamic scan, and 17 lesions (85%) on the delayed scan. Overall diagnostic accuracy for detecting malignant lesions based on the FDG count increase was similar with the whole-body dynamic scan (26/46: 56%) and the delayed scan (29/46: 63%). The dynamic scan showed positive predictive value of 57% (24/42) and negative predictive value of 50% (2/4) for identifying malignant lesions. These values were similar with those of the delayed scan. Based on the FDG count increases, the findings on the dynamic scan matched with those on the delayed scan in 84% (39/46). Conclusions: This preliminary study indicates that the FDG count changes on the whole-body dynamic scan in 12 min starting at 60 minutes may estimate those on 90 -120 min delayed scan. The dynamic scan showed similar predictive values for identifying malignant lesions with those on the delayed scan based on the FDG count changes. When the whole-body dynamic scan showed count increase in the lesion, the conventional delayed scan may be eliminated. We may need more experiences of the whole-body dynamic FDG-PET to see whether the delayed FDG scan may be minimized in order to assess tissue characterization.