Note 4 - Revenue From Contracts With Customers - Disaggregation of Revenue (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue from contract with customer	$ 38,000	$ 338,000
Royalty [Member]
Revenue from contract with customer	16,665	15,347
Royalty [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer	16,665	15,347
NAV4694 Sublicense [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer	9,953	287,569
Product and Service, Other [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer	11,024	15,037
License [Member]
Revenue from contract with customer	9,953	307,174
License [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer	9,953	307,174
Europe [Member] \| Royalty [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer	$ 16,665	15,347
CHINA \| Expanded Tc99m Tilmanocept License Agreement [Member] \| Diagnostics Segment [Member]
Revenue from contract with customer		$ 19,605