Note 2 - Property and Equipment - Summary of Property and Equipment (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Property and equipment, gross		$ 74,237,000
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization, Total	$ 74,425,000
Accumulated depreciation	(52,129,000)	(50,770,000)
Net property and equipment	22,296,000	23,467,000
Property and equipment, net	22,296,000	23,467,000
Non-US [Member]
Net property and equipment	2,020,000	2,201,000
Property and equipment, net	2,020,000	2,201,000
Medical Equipment and Facilities [Member]
Property and equipment, gross	73,911,000	73,709,000
Office Equipment [Member]
Property and equipment, gross	419,000	422,000
Construction in Progress [Member]
Property and equipment, gross	$ 95,000	$ 106,000