Radioligands for myelin

1. A method of detecting myelin in vivo in a subject's tissue, the method comprising:

(i) administering to the subject a radioligand including a compound having the formula:

R 2 is H, or NHR′, where R′ is a lower alkyl group;

R 3 is a radiolabeled lower alkyl group, alkylene group, alkenyl group, alkynyl group, or alkoxy group;

wherein R 3 includes a radiolabeled group having a radiolabel selected from the group consisting of 18 F, 123 I, 125 I, and 99m Tc; or a pharmaceutically acceptable salt thereof; and

(ii) detecting the location, distribution, and/or amount of the radioligand that is bound to and/or labels myelin to detect myelin in the tissue.

2. The method of claim 1 , wherein the radioligand has the formula:

wherein R 2 is H, or NHR′, where R′ is a lower alkyl group;

X 1 is a lower alkyl group, alkylene group, alkenyl group, alkynyl group, or alkoxy group;

Y 1 is a radiolabel selected from the group consisting of 18 F, 123 I, 125 I, and 99m Tc; or a pharmaceutically acceptable salt thereof.

3. The method of claim 1 , wherein the radioligand has the formula:

R 2 is H, or NHR′, where R′ is a lower alkyl group;

n 1 is 1 to 6;

Y 1 is a radiolabel selected from the group consisting of 18 F, 123 I, 125 I, and 99m Tc; or a pharmaceutically acceptable salt thereof.

4. The method of claim 1 , wherein the radioligand has the formula:

or pharmaceutically acceptable salts thereof.

5. The method of claim 1 , the radioligand is detected by in Positron Emission Tomography (PET) imaging or micro Positron Emission Tomography (microPET) imaging.

6. The method of claim 1 , further comprising the step of administering the radioligand to the subject parenterally.

7. The method of claim 1 , wherein the radioligand further comprises a chelating group or a near infrared imaging group.

8. A method of detecting a myelin related disorder in a subject in need thereof, the method comprising the steps of:

(i) administering to the subject a radioligand that includes a compound having the formula:

R 2 is H, or NHR′, where R′ is a lower alkyl group;

R 3 is a radiolabeled lower alkyl group, alkylene group, alkenyl group, alkynyl group, or alkoxy group;

wherein R 3 includes a radiolabeled group having a radiolabel selected from the group consisting of 18 F, 123 I, 125 I, and 99m Tc; or a pharmaceutically acceptable salt thereof;

(ii) detecting the distribution and/or amount of the radioligand in a region of interest in tissue of the subject; and

(iii) comparing the detected distribution and/or amount of the radioligand to a control, wherein a decreased distribution and/or amount of the radioligand compared to the control is indicative of a decrease in myelination of the tissue and the presence of myelination related disorder.

9. The method of claim 8 , wherein the radioligand has the formula:

or pharmaceutically acceptable salts thereof.

10. The method of claim 8 , wherein the radioligand is detected using Positron Emission Tomography (PET) or micro Positron Emission Tomography (microPET) imaging modality.

11. The method of claim 8 , further comprising the step of administering the radioligand to the subject parenterally.

12. The method of claim 8 , wherein the radioligand further comprises a chelating group or a near infrared imaging group.

13. The method of claim 8 , wherein the myelin related disorder is a neurodegenerative autoimmune disease.

14. The method of claim 13 , wherein the neurodegenerative autoimmune disease is multiple sclerosis.