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In this project, we propose to investigate the feasibility of a novel technology that will bring both PET and ultrasound imaging to the patient bedside to support point-ofcare(PoC) molecular imaging applications. The system will comprise of a panel detector placed behind the patient and a maneuverable probe that consists of a PET detector and an ultrasound transducer. The probe can be moved around a region-of-interest in the patients’ body to collect both PET coincidence events and ultrasound signals. The location of the maneuverable probe relative to the back panel detectors is tracked in real-time as coincidence events are recorded. These events are used for list-mode image reconstruction in near realtime to provide visual feedback to the operator who can interactively control the probe to collect additional counts from the most critical locations and/or angles in order to dynamically optimize the image quality. To prove the concept, we developed a prototype that consists of a single channel SiPM(SensL FB30035) coupled to a 3.0 $\times$3.0$\times$20.0 mm$^{ 3}$ LSO crystal as the back detector. The maneuverable probe consists of an ultrasound transducer and a PMT(Hamamatsu H8500) coupled to 48$\times$48 LSO crystals of 1.0$\times$1.0$\times$10.0 mm$^{ 3}$ each. A robotic arm allows us to position the probe at arbitrary locations. Coincidence timing resolution of 470 ps FWHM has been achieved. We have implemented a GPUbased fully 3D list-mode Time-Of-Flight image reconstruction algorithm that can model the dynamically changing geometry of this PoC system. In this study, we report preliminary results from both actual experiments using this prototype and simulations using GATE. Detector modules with larger sensitive volume will be fabricated and tested to perform more imaging studies in order to explore the capability of this class of system.

This paper describes the integration of Hartford Hospital's current 12-lead electrocardiogram (ECG) software with the hospital's information systems (admit, discharge, transfer (ADT); orders; and billing) by engineering a Health Level Seven Standard Interface (HL7) specifically for the hospital's unique software amalgamation. Data formats for the wireless transmission of information were investigated. Distinctive requirements, work-flow, and validation procedures for interfacing the 12-lead ECG system using the HL7 standard were configured. Lastly, the implementation of a wireless transmission component was also developed so completed ECGs could be instantaneously sent to the ECG software directly from the ECG machine, where the analysis was performed. Spectrum analysis was utilized to scrutinize the hospital's current unique wireless infrastructure.

Non-invasive laser-induced photoacoustic tomography (PAT) is a promising imaging modality for the biological imaging field due to the intrinsic optical contrast of tissue and the high resolution of ultrasound. In contrast to common experimental setups that employ a single ultrasound transducer rotating around the target, we present a fast PAT system employing a 128-element curved ultrasound transducer array, parallel signal amplifier circuitry, and multi-channel data acquisition. Two-dimensional photoacoustic images of various phantoms and blood tubing were reconstructed based on the delay-and-sum algorithm. The reconstructed images agreed well with the original samples. The spatial resolution of the system reaches 0.2 mm, which matches the theoretical calculation. The device and methodology provide a rapid and reliable approach to imaging biological tissues and may have potential applications in noninvasive imaging and clinical diagnosis.

In this paper, the electronic architecture used in the implementation of a 128-channel biomedical photo-acoustic imaging system is described. The goal of our research was to verify that the electronic system developed is well-suited for our photo-acoustic imaging application. In essence, we investigated the analog front end for our imaging system, including the data acquisition system. The imaging system described herein was designed for use with a 128-element circularly phased transducer array, with an approximate bandwidth of 9 MHz, centered about 5.5 MHz. Our implemented architecture was highly specific for our research application. Specifically, we relaxed any usual transducer probe size limitations to allow us to bring the entire analog front end as close to the transducer insertion point as possible. In our case, each of the 128 transducer elements has a dedicated high-gain, low-noise, pre-amplifier stage within five inches. Even though our end user application is photo-acoustic imaging, other imaging modalities, such as conventional ultrasonic imaging, can be supported.

We present, to our knowledge, the first quantitative comparisons of five flow estimation algorithms for optical Doppler coherent tomography. We have used simulated 1D, 2D, and in vivo blood flow data to investigate the estimation accuracy and sensitivity of these algorithms. We introduce, among these five methods, 3 new algorithms: weighted centroid, sliding-window filtering, and autocorrelation. The weighted centroid, sliding-window filtering and the existing adaptive centroid algorithms have considerably higher sensitivity and accuracy over the autocorrelation and existing cross-correlation methods.

Wound care technology is rapidly advancing, yet the treatment of wounds remains as much art as science. Much of the data currently collected on healing wounds is qualitative-varying by assessor and not easily tracked over time. The purpose of this research project is to evaluate several methods for quantitative wound assessment-wound volume, wound area, and wound coloration. By comparing various assessment parameters for the same patient population, conclusions can be drawn on which information is most useful to the clinical community and which information can be collected in a reasonable amount of time in the busy environment of the health care clinic.

The imaging reconstruction of near infrared (NIR) diffusive light is in general underdetermined and ill-posed. We have proposed a novel combined approach by using a priori knowledge acquired from co-registered ultrasound to overcome the NIR inversion problem. In this paper we report simulation and experimental results on combined imaging, and we show that NIR reconstruction with the aid of co-registered ultrasound is well defined and the reconstructed optical properties are more accurate than NIR imaging alone.

We introduce a novel imaging technique that combines the best features of ultrasound and near infrared diffusive light imaging in breast cancer detection. The combined technique has been tested in phantoms and preliminary results have shown that it is feasible to implement both acoustic and optical sensors on the same transducer probe and obtain both acoustic and optical parameters of the same target.

Three-dimensional (3-D) ultrasound imaging has been the subject of intense recent interest. However, 3-D imaging requires 2-D planar ultrasound arrays. The fabrication techniques of such arrays are sophisticated and are currently under intensive studies in industry and in a few research labs. We present here an effective 3-D ultrasound imaging system consists of a simple 2-D piezoelectric (PZT) array and low noise front-end electronics. Imaging is obtained by using a synthetic beamforming algorithm and imaging quantity is improved by incorporating a phase deaberration algorithm. The algorithm compensates time-delay errors introduced primarily by the imperfect geometry of the array. The system has good signal to noise ratio and can be used in research applications for demonstrating principles of 3-D imaging related techniques.

Correlation based phase-aberration correction algorithms self-calibrate the receiving array for the correlated phase errors. However, they are insensitive to severe amplitude errors. A highly refractive medium between a target and the receiving transducer can cause significant amplitude errors due to the phase cancellations of multiple arrivals at the receiving array. The authors experimentally evaluate the tolerance of the single-lag spatial correction algorithm to measured amplitude errors across the receiving aperture when a single source (single transducer element) is imaged through a refractive medium, the female breast. The amplitude RMS is linearly inversely related to the peak image amplitude and linearly directly related to the peak sidelobe after the phase correction. >

A novel imaging method which combines ultrasound and NIR optical images provides a new way to utilize optical contrast and ultrasound imaging capability and has a great potential to independently distinguish tumor from normal tissues. The key technical issue for the combined ultrasound and NIR breast imaging is the co-registration of ultrasound and optical images. Co-registration enables the joint evaluation of acoustic and optical properties of the breast lesion and thereby improving detection sensitivity and specificity. Two issues have to be addressed regarding co-registration. First is the optimal deployment of an ultrasound array and optical sensors so that both imaging sensors view the same geometry of the breast. Second is the collocation of images of the same target obtained from ultrasound and NIR light. Since sound and diffusive light propagation paths are different, ultrasound and optical images of the same target may not be collocated. The experimental results reported in this paper demonstrate that an ultrasound array and NIR sensors can be optimally deployed on the same probe and co-registration can be achieved.

1.75 D arrays allow limited beam steering in elevation, which is valuable for three-dimensional (3-D) imaging within a certain field of view. 3-D imaging has important advantage in detecting and visualizing small lesions from multiple viewing angles. Recently, Tetrad Inc has manufactured 1.75 D arrays using the state-of-the-art technologies. The array we have consists of 10 rows in elevation and 128 elements in azimuth, 1280 elements in total. The central frequency of the array is 5 MHz and the bandwidth is 60%. We have constructed 1280 parallel transmission circuitry, 1280 to 40 multiplexing and 40 parallel receiving circuitry. Upon each transmission, 1280-element RF signals were multiplexed to 40 parallel electronic channels, amplified, sampled and stored in the PC. The elevation performance of the array was evaluated through simulations and experiments using a point target. The parameters evaluated were -6 dB, -20 dB beamwidths and grating lobe strength.

The authors have designed a 1.75-D 1280-channel ultrasound imaging system to replace their existing 2-D 64 channel ultrasound imaging system which is used in a combined ultrasound and near infrared (NIR) diffusive light imager for breast cancer imaging. The new system has a 1.75-D 1280 channel ultrasound transducer array, 1280 transmission channels, 1280 to 40 mux, and a 40-channel data acquisition board. This new ultrasound system will provide better image and more detailed information of the human breast to help the optical reconstruction.

A 1280-element, high resolution, ultrasound array transducer operating at 5 MHz has been constructed by Tetrad Inc. We are currently studying the beamforming schemes and parameter tradeoffs of this 1.75 D array system and will present our simulation results.

The authors have designed a prototype two-dimensional ultrasound and near infrared (NIR) diffusive light imager for simultaneous imaging. Here, they show preliminary results obtained from an improved imager which replaces the lower resolution ultrasound system in the combined imager with a high resolution 1.75 D ultrasound array.

OCT images can be degraded severely by coherent sidelobes of the source. Sidelobes, can introduce false targets if no targets are present at the sidelobe locations, and also add constructively or destructively to the targets that are present at the sidelobe locations, resulting in cancellation of the true targets or display of incorrect echo amplitudes of the targets. The authors introduce the use of CLEAN, a nonlinear deconvolution algorithm, to cancel coherent sidelobes in OCT images of extracted human teeth. The results show that CLEAN can reduce the coherent artifacts to the noise background, sharpen the air-enamel and enamel dentin interfaces and improve the image contrast.

Diffusive light through human tissues has been used to investigate the functional status of the human body. Accumulated efforts have been made to bring this technique to a clinically acceptable stage. Here, the authors present a new reconstruction method for near infrared (NIR) diffusive tomography. Its usefulness is manifested by reconstructed images from both simulated and experimental data. The authors conclude that their new algorithm is efficient in translating measured diffusive photon density waves into high quality images of optical properties.

Doppler optical coherence tomography (Doppler OCT) is a technique combining Doppler velocimetry with optical coherence tomography to measure fluid flow velocity at discrete spatial locations. Doppler OCT is an accurate method for the characterization of high resolution (

A combined ultrasound and near infrared (NIR) diffusive light imager capable of simultaneous three-dimensional (3-D) volumetric imaging and co-registration is constructed. The ultrasound imaging system consists of a 64-element 2-D array and 64 parallel transmission and reception channels. The NIR imaging system consists of an array of 12 dual-wavelength (780nm and 830nm) laser diode sources and 8 photomultiplier (PMT) detectors as well as associated electronics. The combined imager can provide near real-time ultrasound and optical images suitable for clinical experiments.

Optical coherence tomography (OCT) is an important imaging technique for medical applications. In this work we report our results on imaging of periodontal tissue. Our OCT system utilizes an erbium doped fiber amplifier emitting near 1.55 /spl mu/m as the source. The coherence length of the source can be varied by more than a factor of 5 by varying the current of the pump laser used in the amplifier. This allows an easy adjustment and a trade-off study of depth of penetration and resolution. The output power of the source can also be varied to allow high penetration depth. Measurement and analysis of the signal to noise of our system and images of periodontal tissue are presented.

We discuss in the paper the most probable paths related to frequency domain diffuse photon density waves propagating inside turbid media. It is found that for a medium of finite size, the existence of boundaries to non-scattering media would have considerable impact on the path shape. It is also demonstrated that such paths can be used to obtain higher accuracy in localizing absorbers embedded in a homogeneous background.