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Note 7 - Share-based Payment Awards (Details Textual) - USD ($) |  | 9 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Dec. 31, 2018 | Sep. 30, 2025 | Sep. 30, 2024 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Common Stock, Capital Shares Reserved for Future Issuance, Increase (in shares) |  |  |  | 1,068,323 | 1,027,522 | 1,014,124
Common Stock, Shares, Outstanding (in shares) |  | 26,817,535 |  | 26,709,084 | 25,688,062 | 25,353,119
Share-Based Payment Arrangement, Expense |  | $ 4,388,000 | $ 2,383,000 |  |  |
Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount |  | $ 5,792,000 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares) |  | 108,451 | 2,500 |  |  |
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share) |  | $ 3.63 | $ 2.97 |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value |  | $ 1,167 | $ 2,000 |  |  |
Share-Based Payment Arrangement, Option [Member] |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  | $ 3,747,000 | 1,991,000 |  |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  | 2 years 7 months 6 days |  |  |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  | $ 611,000 | 171,000 |  |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  | 2 years 8 months 12 days |  |  |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount |  | $ 2,239,000 |  |  |  |
General and Administrative Expense [Member] |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  | 4,268,000 | 2,138,000 |  |  |
Research and Development Expense [Member] |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  | $ 120,000 | 245,000 |  |  |
The 2018 Plan [Member] |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares) |  | 1,076,595 |  |  |  |
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) |  | 842,581 |  |  |  |
Common Stock, Capital Shares Reserved for Future Issuance, Increase (in shares) | 150,000 |  |  |  |  |
Share-Based Payment Arrangement, Expense |  | $ 30,000 | $ 145,000 |  |  |
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) |  | 0 |  |  |  |
Employee-related Liabilities, Current |  | $ 145,000 |  | $ 42,000 |  |

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