Intravascular imaging detector
An apparatus for intravascular imaging to detect and characterize early stage, unstable coronary arty plaques. The detector works by identifying and localizing plaque-binding beta-emitting radiopharmaceuticals.
1 . An imaging catheter comprising:
a catheter body comprising a proximal portion and a distal portion;
a flexible membrane disposed at the distal portion of the catheter body, wherein the flexible membrane is movable between a deflated position and an inflated position; and
an array of radiation detectors coupled to the flexible membrane.
2 . The catheter of claim 1 wherein the radiation detector comprises:
a liquid scintillator disposed within the flexible membrane, wherein the liquid scintillator can absorb a beta particle and emit a first scintillation light; and
a scintillator optically coupled to a distal end of an optical fiber, wherein the scintillator is disposed within the flexible membrane to absorb the first scintillation light from the liquid scintillator and to transmit a second scintillation light down the optical fiber.
3 . The catheter of claim 2 comprising a moveable shield disposed over the scintillator.
4 . The catheter of claim 2 further comprising a photodetector coupled to a proximal end of the optical fiber to receive the second scintillation light.
5 . The catheter of claim 2 wherein the catheter body comprises a lumen for delivering the liquid scintillator into the flexible membrane.
6 . The catheter of claim 2 wherein the flexible membrane in the inflated configuration has a diameter that is between approximately two and three times larger than the diameter of the flexible membrane in the deflated configuration.
7 . The catheter of claim 2 wherein the scintillator has a length between approximately five centimeters and ten centimeters.
8 . The catheter of claim 2 wherein the first scintillation light has a shorter wavelength than the second scintillation light transmitted down the optical fiber.
9 . The catheter of claim 1 wherein the radiation detectors comprise a series of semiconductor radiation detectors attached to the flexible membrane.
10 . The catheter of claim 9 wherein the semiconductor detectors are Si-pin diodes.
11 . The catheter of claim 9 wherein the flexible membrane in the expanded configuration presses the semiconductor radiation detectors against a radiopharmaceutical coupled to a wall of a body lumen.
12 . The catheter of claim 9 wherein the flexible membrane comprises an inner and outer layer, wherein the semiconductor radiation detectors are disposed between the inner and outer layer.
13 . The catheter of claim 9 wherein the flexible membrane in the inflated configuration is filled with Xenon.
14 . The catheter of claim 1 further comprising:
an inner electrode disposed within the flexible membrane;
a moveable insulating sleeve disposed over the inner electrode;
an outer electrode attached to the flexible membrane; and
an Xenon gas disposed in the flexible membrane.
15 . The catheter of claim 14 further comprising a mesh insulator disposed between the outer electrode and the inner electrode.
16 . A method of locating and characterizing radiopharmaceuticals in a body lumen, the method comprising:
advancing a catheter through the body lumen; and
expanding a flexible membrane on the catheter to move the radiation detectors closer to the radiopharmaceuticals in the body lumen.
17 . The method of claim 16 comprising operating the radiation detectors in search mode to determine the presence of radiopharmaceuticals in the body lumen.
18 . The method of claim 17 wherein expanding is carried out when it is determined from the search mode that a concentration of radiopharmaceuticals are present in the portion of the body lumen.
19 . The method of claim 18 comprising switching the radiation detectors to an imaging mode to obtain a high resolution of the radiopharmaceuticals.
20 . The method of claim 16 comprising attaching the radiopharmaceuticals to unstable plaque.
21 . The method of claim 16 wherein the radiation detectors comprise a semiconductor radiation detector, a scintillator, an ionization chamber, or an imaging plate.
22 . The method of claim 16 wherein the flexible membrane is in a deflated configuration during advancing.
23 . The method of claim 16 wherein the radiation detectors provide a spatial resolution of one millimeter to three millimeters.
24 . The method of claim 16 wherein advancing comprises moving the catheter over a guidewire.
25 . The method of claim 16 comprising transmitting information from the radiation detector to data acquisition electronics.
26 . A kit comprising:
a catheter comprising at least one radiation detector disposed on an expandable flexible membrane;
instructions for use comprising advancing the catheter to a target site and expanding the balloon from a deflated configuration to an expanded configuration; and
a package adapted to contain the device and the instructions for use.