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Note 10 - Stockholders' Equity (Tables) | 9 Months Ended
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Sep. 30, 2025
Notes Tables |
Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] |
|  | 2025 |  |  | 2024 |
Dividend yield |  |  | 0.0 | % |  |  | 0.0 | %
Expected volatility |  |  | 81.5 | % |  |  | 85.8 | %
Risk-free interest rate |  |  | 4.4 | % |  |  | 4.1 | %
Expected life in years |  |  | 5.55 |  |  |  | 5.55 |
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] |
|  | For the Three Months Ended |  |  | For the Nine Months Ended |
|  | September 30, |  |  | September 30, |
|  | 2025 |  |  | 2024 |  |  | 2025 |  |  | 2024 |
Stock-based compensation: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Options: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Selling, general, and administrative |  | $ | 236 |  |  | $ | 386 |  |  | $ | 781 |  |  | $ | 1,247 |
Research and development |  |  | 31 |  |  |  | 57 |  |  |  | 124 |  |  |  | 234 |
Restricted stock units: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Selling, general, and administrative |  |  | 815 |  |  |  | 1,056 |  |  |  | 2,497 |  |  |  | 3,081 |
Research and development |  |  | 591 |  |  |  | 555 |  |  |  | 1,925 |  |  |  | 1,931 |
Total stock-based compensation expense |  | $ | 1,673 |  |  | $ | 2,054 |  |  | $ | 5,327 |  |  | $ | 6,493 |
Share-Based Payment Arrangement, Activity [Table Text Block] |
|  | Shares |  |  | Weighted Average Exercise Price |  |  | Weighted Average Remaining Contractual Term (years) |  |  | Aggregate Intrinsic Value (in thousands) |
Outstanding at December 31, 2024 |  |  | 4,051,928 |  |  | $ | 33.80 |  |  |  |  |  |  |  |  |
Granted |  |  | 492,514 |  |  |  | 2.78 |  |  |  |  |  |  |  |  |
(Forfeited) |  |  | (84,954 | ) |  |  | 3.57 |  |  |  |  |  |  |  |  |
(Exercised) |  |  | (55,882 | ) |  |  | 2.33 |  |  |  |  |  |  |  |  |
(Expired) |  |  | (850,176 | ) |  |  | 60.00 |  |  |  |  |  |  |  |  |
Outstanding at September 30, 2025 |  |  | 3,553,430 |  |  | $ | 21.73 |  |  |  | 5.1 |  |  | $ | 2,774 |
Vested and expected to vest at September 30, 2025 |  |  | 3,553,430 |  |  | $ | 21.73 |  |  |  | 5.1 |  |  | $ | 2,774 |
Exercisable |  |  | 3,147,703 |  |  | $ | 24.07 |  |  |  | 4.6 |  |  | $ | 1,964 |
Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] |
|  | Shares |  |  | Weighted Average Grant-Date Fair Value |
Nonvested shares at December 31, 2024 |  |  | 1,289,449 |  |  | $ | 5.14 |
Granted |  |  | 1,406,086 |  |  | $ | 3.34 |
(Forfeited) |  |  | (114,209 | ) |  | $ | 4.02 |
(Vested) |  |  | (1,222,558 | ) |  | $ | 4.60 |
Nonvested shares at September 30, 2025 |  |  | 1,358,768 |  |  | $ | 3.86 |

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- Definition Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Tabular disclosure of activity for award under share-based payment arrangement. Includes, but is not limited to, outstanding award at beginning and end of year, granted, exercised, forfeited, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (d) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (e) -SubTopic 10 -Topic 718 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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