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Note 3 - Investments and Agreements (Details Textual) - USD ($)								3 Months Ended		6 Months Ended
	Feb. 18, 2025	Jan. 08, 2025	May 24, 2024	Apr. 11, 2024	Mar. 04, 2024	Jan. 17, 2024	Jan. 08, 2024	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Aug. 13, 2024	Mar. 31, 2024	Dec. 14, 2023	Nov. 17, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock, par value								$ 0.001		$ 0.001		$ 0.001
Other income from a related party								$ 0	$ 0	$ 1,400,000	$ 0
Maximum amount of securities offer and sell															$ 200,000,000
January 2024 Pre-funded Warrants [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Warrants to purchase shares of common stock						3,008,694
Warrant exercise price per share						$ 3.69
Percentage of ownership considered for warrant exercise						4.99%
Maximum increase or decrease in ownership percentage						19.99%
2024 At-the-Market (ATM) Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Agent commission fee as a percentage of gross sales price													3.00%
Stock issued during period, shares	3,379,377
Stock purchase price per share	$ 3.02
Proceeds from issuance of common stock	$ 10,200,000
2024 At-the-Market (ATM) Agreement [Member] \| Common Stock [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Maximum amount of securities offer and sell													$ 250,000,000
March 2024 Private Placement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares					9,200,998
Stock purchase price per share					$ 9.5
Proceeds from issuance of common stock					$ 87,400,000
Placement agents cash fee, percentage					5.85%
Lantheus Investment Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares							5,634,235
Investment agreement, contingent amount of gross proceeds raised							$ 50,000,000
Percent of outstanding shares							19.99%
Asset purchase price in cash							$ 8,000,000
Lantheus Investment Agreement \| Option Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Percent of outstanding shares														19.90%
Other income from a related party		$ 1,400,000
One-time payment received for rights granted							28,000,000
Repayment provisions							$ 0
Public Offering [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares						13,207,521
Sale of stock, price per share						$ 3.7
Shares and warrants, price difference per share						$ 0.01
Gross proceeds from public offering						$ 69,000,000
Over-Allotment Option [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares						2,432,432
Oppenheimer & Co [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares				3,535,246
Stock purchase price per share				$ 14
Proceeds from issuance of common stock				$ 49,500,000
Maximum amount of securities offer and sale																$ 50,000,000
BofA Securities, Inc [Member] \| Underwriting Agreement [Member] \| May 2024 Pre-funded Warrants [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Warrants to purchase shares of common stock			146,425
Warrant exercise price per share			$ 15.09
Percentage of ownership considered for warrant exercise			4.99%
Percentage of ownership considered for warrant exercise			9.99%
Maximum increase or decrease in ownership percentage			19.99%
BofA Securities, Inc [Member] \| Registered Offering [Member] \| Underwriting Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Stock issued during period, shares			5,151,588
Sale of stock, price per share			$ 15.1
Shares and warrants, price difference per share			$ 0.01
Gross proceeds from public offering			$ 80,000,000