The laser optoacoustic imaging system described herein utilizes time-resolved measurement of profiles of laser-induced transient pressure (acoustic) waves. The pressure waves are emitted by acoustic sources preferentially generated in absorbing tissues of diagnostic interest. This technique allows visualization of absorbed light distribution in turbid, layered and heterogeneous tissues irradiated by laser pulses in vivo. The laser optoacoustic tomography can be used for the characterization of structure and properties of normal tissue, and for the detection of tissue pathological changes. The optical heterogeneities that can be imaged with the laser optoacoustic imaging system include abnormal tissues such as tumors, injured tissues, blood vessels and other layered tissues. Further, three dimensional images of organs and portions of organs can be obtained.

Optoacoustic imaging for medical diagnosis

This invention is a catheter-based device for generating an ultrasound excitation in biological tissue. Pulsed laser light is guided through an optical fiber (10) to provide the energy for producing the acoustic vibrations. The optical energy is deposited in a water-based absorbing fluid, e.g. saline, thrombolytic agent, blood or thrombus, and generates an acoustic impulse in the fluid through thermoelastic and/or thermodynamic mechanisms. By pulsing the laser at a repetition rate (which may vary from 10 Hz to 100 kHz) an ultrasonic radiation field can be established locally in the medium. This method of producing ultrasonic vibrations can be used in vivo for the treatment of stroke-related conditions in humans, particularly for dissolving thrombus or treating vaspasm. The catheter (14) can also incorporate thrombolytic drug treatments as an adjunct therapy and it can be operated in conjunction with ultrasonic detection equipment for imaging and feedback control and with optical sensors for characterization of thrombus type and consistency.

Opto-acoustic thrombolysis

An optoacoustic apparatus is disclosed which includes a radiation source of pulsed radiation and a probe having a front face to be placed in contact with a tissue site of an animal body. The probe further includes an optical fiber terminating at the surface of the front face of the probe and connected at their other end to a pulsed laser. The front face of the probe also has mounted therein or thereon a piezoelectric transducer for detecting an acoustic response to the radiation pulses connected to a processing unit which converts the transducer signal into a measure of hemoglobin concentration and/or hematocrit of blood.

Continuous optoacoustic monitoring of hemoglobin concentration and hematocrit

An optoacoustic apparatus is disclosed which includes a radiation source of pulsed radiation and a probe having a front face to be placed in close proximity to or in contact with a tissue site of an animal body. The probe further includes a plurality of optical fibers terminating at the surface of the front face of the probe and connected at their other end to a pulsed laser. The front face of the probe also has mounted therein or thereon a transducer for detecting an acoustic response from blood in the tissue site to the radiation pulses connected to a processing unit which converts the transducer signal into a measure of venous blood oxygenation.

Optoacoustic monitoring of blood oxygenation

A medical device is provided which comprises a suction conduit and an energy-transmitting conduit wherein at least some of the transmitted energy is directed to the distal region of the suction conduit. The device may include an optical apparatus for directing the energy. The device has applications in lithotripsy and tissue-removal in a patient.

Laser lithotripsy device with suction

A shock wave generator for the fragmentation of concrements, having a light-pulse-transmiting light guide and a converter arranged at the distal light guide end and having an ionization surface which, when a light pulse impinges, initiates a shock wave in the surrounding fluid, as well as having a shock wave outlet zone. In order to increase its efficiency and durability, the generator is constructed such that the ionization surface extends obliquely sloped with respect to the beaming axis of the impinging light pulse and the shock wave outlet zone is arranged in the direct shock wave beaming area of the ionization surface, thereby permitting a largely unhindered, low-loss propagation for the shock wave to the application point.

Stephan Thomas

Papers

Shock wave generator