Note 5 - Accrued Liabilities - Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accrued interest	$ 1,102	$ 0
Accrued bonuses	606	1,209
Accrued payroll and other related expenses	545	495
Deferred revenue - subscription rental program	464	452
Accrued clinical trial costs	306	337
Accrued professional fees	201	120
Other accruals	187	215
Total accrued liabilities	3,655	3,053
Accrued Liabilities [Member]
Current operating lease liabilities	$ 244	$ 225