The U.S. market for radiopharmaceuticals and devices looks promising, thanks to emerging agents, according to a Bio-Tech Systems report. The report predicts growth in PET sales of more than 20% in 2013, fueled in part by new imaging agents for Alzheimer's disease. Sales may grow to $4.7 billion by 2021, the report found. SPECT sales growth is estimated at 6% this year, and sales could reach $1.7 billion by 2021. "This will stimulate more research and investment, adding strength and stability to venture companies, as well as those more established in the field," according to the authors of the report.