Note 6 - Property and Equipment, Net - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property and equipment, gross	$ 927	$ 882
Less accumulated depreciation	(758)	(771)
Property and equipment, net	169	111
Computer Equipment and Software [Member]
Property and equipment, gross	106	143
Laboratory and Manufacturing Equipment [Member]
Property and equipment, gross	447	366
Furniture and Fixtures [Member]
Property and equipment, gross	48	48
Leasehold Improvements [Member]
Property and equipment, gross	$ 326	$ 325

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Section 50
-Paragraph 1
-Subparagraph (b)
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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Subparagraph (SX 210.5-02(13))
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