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Note 9 - Share-based Payment Awards (Details Textual) - USD ($) $ / shares in Units, $ in Thousands |  |  | 1 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jan. 01, 2023 | Dec. 31, 2018 | Jul. 31, 2017 | Sep. 30, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Jan. 01, 2024 | May 30, 2017
Common Stock, Capital Shares Reserved for Future Issuance, Increase (in shares) | 1,014,124 |  |  |  |  |  |  | 1,027,522 |
Common Stock, Shares, Outstanding (in shares) |  |  |  |  | 26,709,084 | 25,688,062 | 25,353,119 |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares) |  |  |  |  | 1,621,118 |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 3,165 | $ 3,137 | $ 4,218 |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value |  |  |  |  | $ 1,867 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares) |  |  |  |  | 266,353 | 207,626 | 25,000 |  |
Proceeds from Stock Options Exercised |  |  |  |  | $ 1,191 | $ 149 | $ 35 |  |
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount |  |  |  |  | $ 5,390 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) |  |  |  |  | $ 2.2 |  |  |  |
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares) |  |  |  |  | 80,933 | 86,782 | 69,884 |  |
General and Administrative Expense [Member] |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 2,899 | $ 2,864 | $ 3,954 |  |
Research and Development Expense [Member] |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 266 | 273 | $ 264 |  |
Consultant [Member] |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year) |  |  |  |  | 5 years |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares) |  |  | 50,000 |  |  |  |  |  |
Two Senior Executives [member] |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit (in dollars per share) |  |  |  |  |  |  | $ 1.37 |  |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) |  |  |  |  |  |  | $ 8.61 |  |
Share-based Payment Arrangement, Plan Modification, Modification Expense |  |  |  |  |  |  | $ 104 |  |
Senior Executive [Member] |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Option, Exercise Price Range, Lower Range Limit (in dollars per share) |  |  |  |  | $ 3.47 |  |  |  |
Share-Based Payment Arrangement, Option, Exercise Price Range, Upper Range Limit (in dollars per share) |  |  |  |  | $ 8.61 |  |  |  |
Share-based Payment Arrangement, Plan Modification, Modification Expense |  |  |  |  | $ 75 |  |  |  |
Share-Based Payment Arrangement, Option [Member] |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year) |  |  |  | 10 years | 10 years |  |  |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 241 | 239 | 114 |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount |  |  |  |  | $ 740 |  |  |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  |  |  |  | 2 years 2 months 12 days |  |  |  |
The 2017 Plan [Member] | Common Stock [Member] |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares) |  |  |  |  |  |  |  |  | 5,000,000
The 2018 Plan [Member] |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares) |  |  |  |  | 692,581 |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Annual Increase in Share Reserve as a Percent of Outstanding Common Stock |  |  |  |  | 4.00% |  |  |  |
The 2018 Employee Stock Purchase Plan [Member] |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares) |  |  |  |  | 692,581 |  |  |  |
Common Stock, Capital Shares Reserved for Future Issuance, Increase (in shares) |  | 150,000 |  |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 205 | 135 | $ 128 |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ 1.27 |  |  |  | $ 1.35 |  | $ 1.17 |  |
Common Stock, Capital Shares Reserved for Future Issuance (in shares) |  | 150,000 |  |  |  |  |  |  |
Common Stock, Capital Shares Reserved for Future Issuance, Percentage Increase |  | 1.00% |  |  |  |  |  |  |
Employee Stock Purchase Plans, Fair Value of Common Stock Price Per Share on Offering Date, Percentage |  | 85.00% |  |  |  |  |  |  |
Employee Stock Purchase Plans, Fair Value of Common Stock Price Per Share on Purchase Date, Percentage |  | 85.00% |  |  |  |  |  |  |
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares) | 86,782 |  |  |  | 80,933 |  | 69,884 |  |
Employee Stock Purchase Plan (ESPP), Cash Contributions to ESPP |  |  |  |  | $ 283 | 230 | $ 174 |  |
Employee-related Liabilities, Current |  |  |  |  | $ 42 | $ 24 |  |  |

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