Note 3 - Revenue From Contracts With Customers (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

Disaggregation of Revenue [Table Text Block]

	Three Months Ended June 30,				Six Months Ended June 30,
	2022		2021		2022		2021
Sales revenue:
Tc99m tilmanocept - Europe	$	6,519	$	—	$	6,519	$	—
License revenue:
Tc99m tilmanocept - Europe	$	—	$	13,063	$	—	$	35,549

Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]

	Three Months Ended June 30,					Six Months Ended June 30,
	2022			2021		2022			2021
Total deferred revenue, beginning of period	$	800,000		$	700,000	$	700,000		$	700,000
Deferred revenue related to milestones achieved		—			—		100,000			—
Deferred revenue related to milestones achieved, written off due to contract renegotiations		(100,000	)		—		(100,000	)		—
Total deferred revenue, end of period	$	700,000		$	700,000	$	700,000		$	700,000