Note 13 - Revenues - Remaining Performance Obligations (Details)	Dec. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Amount	$ 4,702,000
Service [Member]
Revenue, Remaining Performance Obligation, Amount	1,664,000
Device Revenue [Member]
Revenue, Remaining Performance Obligation, Amount	1,505,000	[1]
Exclusivity Fee [Member]
Revenue, Remaining Performance Obligation, Amount	1,334,000
Clinical Revenue [Member]
Revenue, Remaining Performance Obligation, Amount	$ 199,000

[1] Represents the minimum purchase requirements under the distribution agreement the Company signed with its AXP distributor in China.