Modelling image quality over extended [¹⁸F]FDG uptake times for low-dose positron emission mammography

This study investigated the effect of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) uptake time on image quality in low-dose positron emission mammography (PEM) using kinetic modelling.

Fifteen malignant lesions from thirteen women newly diagnosed with breast cancer were imaged using low-dose [¹⁸F]FDG PEM. Tumour and normal breast tissue time-activity curves (TACs) were generated using a population-based arterial input function (AIF) and a two-tissue compartmental model. Modelling was performed at [¹⁸F]FDG doses of 1, 2, 5, and 10 mCi (37, 74, 185, and 370 MBq), and image quality was assessed using contrast-to-noise ratio (CNR) over a 6-hour uptake period.

Extending uptake times beyond the 1-hour clinical standard significantly improved CNR across all doses, with comparable proportional gains. Relative to 1 hour post-injection, CNR increased by approximately 30% at 1.5 hours, 53% at 2 hours, and 77% at 3 hours, although uncertainty widened at 3 hours and beyond, particularly at the lowest dose (1 mCi). Relatively small variations in uptake time were also found to produce substantial changes in the standardized uptake value (SUV).

These findings demonstrate that extending uptake times by even 30 minutes beyond the 1-hour clinical standard may significantly enhance image CNR for low-dose [¹⁸F]FDG PEM. The sensitivity of SUV to small variations in uptake time supports the need to closely match uptake time between baseline and follow-up scans in treatment response assessment. Overall, these modelling results encourage further clinical research into optimizing uptake time protocols, which may help support the broader adoption of low-dose PEM in future work.

https://clinicaltrials.gov/study/NCT03520218, identifier NCT03520218.