Radiolabeled neurokinin-1 receptor antagonists

1. A compound of the formula:

wherein:

A is —CD 2 — or —CH 2 CH 2 —;

or a pharmaceutically acceptable salt thereof.

2. A compound which is:

[ 18 F][2-fluorodideuteromethoxy-5-(5-trifluoromethyl-tetrazol-1-yl)-benzyl]-([2S,3S]-2-phenyl-piperidin-3-yl)-amine;

or a pharmaceutically acceptable salt thereof.

3. A compound which is:

[ 18 F][3-fluoroethoxy-5-(5-trifluoromethyl-tetrazol-1-yl)-benzyl]-([2S,3S]-2-phenyl-piperidin-3-yl)-amine;

or a pharmaceutically acceptable salt thereof.

4. A radiopharmaceutical composition which comprises the compound of claim 1 and a pharmaceutically acceptable carrier or excipient.

5. A method for the imaging of neurokinin-1 receptor in the brain in a mammal which comprises administering to a mammal in need of such diagnostic imaging an effective amount of the compound of claim 1 , and obtaining an image of the brain in the mammal using positron emission tomography.

6. The method of claim 5 wherein the mammal is a human.