The discomfort of internal gastrointestinal examination may soon be a thing of the past. We have developed a new type of endoscopy, which for the first time allows painless endoscopic imaging of the whole of the small bowel. This procedure involves a wireless capsule endoscope and we describe here its successful testing in humans.

Wireless capsule endoscopy

Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) has the potential to image animal or human organs, such as the breast and the brain, with simultaneous high contrast and high spatial resolution. This article provides an overview of the rapidly expanding field of photoacoustic imaging for biomedical applications. Imaging techniques, including depth profiling in layered media, scanning tomography with focused ultrasonic transducers, image forming with an acoustic lens, and computed tomography with unfocused transducers, are introduced. Special emphasis is placed on computed tomography, including reconstruction algorithms, spatial resolution, and related recent experiments. Promising biomedical applications are discussed throughout the text, including (1) tomographic imaging of the skin and other superficial organs by laser-induced photoacoustic microscopy, which offers the critical advantages, over current high-resolution optical imaging modalities, of deeper imaging depth and higher absorptioncontrasts, (2) breast cancerdetection by near-infrared light or radio-frequency–wave-induced photoacoustic imaging, which has important potential for early detection, and (3) small animal imaging by laser-induced photoacoustic imaging, which measures unique optical absorptioncontrasts related to important biochemical information and provides better resolution in deep tissues than optical imaging.

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Photoacoustic imaging in biomedicine

A surgical instrument useful for laparoscopic surgery comprising an insulated shaft, a control means and a connection to an electrosurgical radiofrequency power source, its distal end being of general J-hook form having a tissue-engaging ledge, and the shaft supporting a tissue-engaging clamping or cutting member movable toward the ledge in response to the control means so that an artery or other tissue in the pocket of the J-hook can be clamped or cut while radiofrequency current is applied. Instrument constructions disclosed incorporate one or two clamping members and a cutting member arranged such that with actuation, the clamping member(s) engages the ledge before the cutting member, and, by selective actuation of the electrosurgical power source, coagulation current can be applied while clamping an artery or other tissue against the ledge to stop flow of blood, and by further actuation of the control and suitable current to the cutting member, the artery or tissue may be cut. Selector means enable movement of one and prevent movement of one of the members during actuation; bipolar or monopolar energization is employed; the relatively long leg of the J-member has portals. Communicating through a lumen in the shaft for infusion or aspiration of fluid; the distal end surface of the J-hook defines a cutting edge for blunt dissection; and the control means comprises a single actuatable member by actuator rods for sealing clamp and cutting members, while a compression spring associated with the actuating rod of the sealing clamp member compresses when the clamp member is stopped, in clamping action upon the artery or tissue while cutting of tissue thereafter proceeds. A diamond film on tissue-engaging surfaces of a clamp, grasping or cutting surgical instrument improves heat transfer between tissue and instrument.

Surgical instrument and method

A self-contained powered surgical stapling apparatus is provided which includes an elongate body, a fastener applying assembly including an anvil for forming a surgical fastener driven thereagainst, a motor assembly and power source for energizing the motor assembly disposed within the elongate body, and a pusher driven by the motor assembly for driving a surgical fastener toward the anvil to be formed thereby and fastened to body tissue. The apparatus is configured for utilization during conventional invasive surgical procedures as well as endoscopic or laparoscopic surgical procedures by providing a detachable extension shaft.

Self-contained powered surgical apparatus

Photoacoustic (PA) imaging, also called optoacoustic imaging, is a new biomedical imaging modality based on the use of laser-generated ultrasound that has emerged over the last decade. It is a hybrid modality, combining the high-contrast and spectroscopic-based specificity of optical imaging with the high spatial resolution of ultrasound imaging. In essence, a PA image can be regarded as an ultrasound image in which the contrast depends not on the mechanical and elastic properties of the tissue, but its optical properties, specifically optical absorption. As a consequence, it offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chomophores, but with greater penetration depth than purely optical imaging modalities that rely on ballistic photons. As well as visualizing anatomical structures such as the microvasculature, it can also provide functional information in the form of blood oxygenation, blood flow and temperature. All of this can be achieved over a wide range of length scales from micrometres to centimetres with scalable spatial resolution. These attributes lend PA imaging to a wide variety of applications in clinical medicine, preclinical research and basic biology for studying cancer, cardiovascular disease, abnormalities of the microcirculation and other conditions. With the emergence of a variety of truly compelling in vivo images obtained by a number of groups around the world in the last 2–3 years, the technique has come of age and the promise of PA imaging is now beginning to be realized. Recent highlights include the demonstration of whole-body small-animal imaging, the first demonstrations of molecular imaging, the introduction of new microscopy modes and the first steps towards clinical breast imaging being taken as well as a myriad of in vivo preclinical imaging studies. In this article, the underlying physical principles of the technique, its practical implementation, and a range of clinical and preclinical applications are reviewed.

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Biomedical photoacoustic imaging

A thread guide device is provided which is adapted to be removably or fixedly mounted on the distal end of an endoscope, or which is an integral part thereof. Alternatively, the device may comprise a head joined to the distal end of an elongate shaft that is slidable within the endoscope. The device has a pair of thread guides, for example in the form of longitudinally extending passages, which are laterally spaced from one another. The device permits a knot formed by threads which have passed through the thread guides to be viewed by the endoscope.

Device for use in tying knots

A device is provided which can act as one component of an anastomosis-forming assembly, i.e. as an anastomosis button. The device comprises a plurality of elongate members having a first, introduction configuration in which they are substantially aligned with one another, and a second, use configuration in which they are disposed at an angle to one another. For example, there may be two such elongate members, which, in the use configuration, form a cross. The device comprises means, for example, a tensionable thread, for bringing the elongate members into the use configuration.

A device for transfixing and joining tissue

The transduction mechanisms of a wideband (30 MHz) contact ultrasound sensor based upon the use of a thin polymer film acting as a Fabry-Perot interferometer have been investigated. Polyethylene terepthalate (PET) sensing elements, illuminated by the free-space collimated output of a wavelength-tunable DBR laser diode, have been used to study the sensor transfer function, sensitivity, the effect of water absorption, and frequency response characteristics. Acoustic performance was evaluated by comparing the sensor output with that of a calibrated PVDF membrane hydrophone using laser-generated acoustic transients as a source of broadband ultrasound. An ultrasonic acoustic phase sensitivity of 0.1 rad/MPa, a linear operating range to 5 MPa, and a noise-equivalent-pressure of 20 kPa over a 25 MHz measurement bandwidth were obtained using a water-backed 50 /spl mu/m PET sensing film. A model of frequency response that incorporates the effect of an adhesive layer between the sensor film and backing material has been developed and validated for different sensing film thicknesses, backing configurations, and adhesive layer thicknesses.

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Transduction mechanisms of the Fabry-Perot polymer film sensing concept for wideband ultrasound detection

Theoretical and experimental aspects of an extrinsic optical-fiber ultrasound sensor are described. The sensor is based on a thin transparent polymer film acting as a low-finesse Fabry-Perot cavity that is mounted at the end of a multimode optical fiber. Performance was found to be comparable with that of a piezoelectric polyvinylidene dinuoride-membrane (PVDP) hydrophone with a sensitivity of 61 mV/MPa, an acoustic noise floor of 2.3 KPa over a 25-MHz bandwidth, and a frequency response to 25 MHz. The wideband-sensitive response and design flexibility of the concept suggests that it may find application as an alternative to piezoelectric devices for the detection and measurement of ultrasound.

Timothy Noel Mills

Papers

Device for use in tying knots

A device for transfixing and joining tissue

Transduction mechanisms of the Fabry-Perot polymer film sensing concept for wideband ultrasound detection

Extrinsic optical-fiber ultrasound sensor using a thin polymer film as a low-finesse Fabry-Perot interferometer.

Sewing or stapling machine