scholarly journals Comparison of Piezoelectric and Optical Projection Imaging for Three-Dimensional In Vivo Photoacoustic Tomography

2019 ◽  
Vol 5 (1) ◽  
pp. 15 ◽  
Author(s):  
Robert Nuster ◽  
Günther Paltauf
Keyword(s):  
Acoustic Field ◽  
Back Propagation ◽  
Three Dimensional ◽  
Sensor Arrays ◽  
Optical Data ◽  
Acquisition Time ◽  
Photoacoustic Tomography ◽  
Light Illumination ◽  
Optical Setup

Ultrasound sensor arrays for photoacoustic tomography (PAT) are investigated that create line projections of the pressure generated in an object by pulsed light illumination. Projections over a range of viewing angles enable the reconstruction of a three-dimensional image. Two line-integrating arrays are compared in this study for the in vivo imaging of vasculature, a piezoelectric array, and a camera-based setup that captures snapshots of the acoustic field emanating from the sample. An array consisting of 64 line-shaped sensors made of piezoelectric polymer film, which was arranged on a half-cylindrical area, was used to acquire spatiotemporal data from a human finger. The optical setup used phase contrast to visualize the acoustic field generated in the leg of a mouse after a selected delay time. Time-domain back projection and frequency-domain back propagation were used for image reconstruction from the piezoelectric and optical data, respectively. The comparison yielded an about threefold higher resolution for the optical setup and an about 13-fold higher sensitivity of the piezoelectric array. Due to the high density of data in the camera images, the optical technique gave images without streak artifacts, which were visible in the piezo array images due to the discrete detector positions. Overall, both detection concepts are suited for almost real-time projection imaging and three-dimensional imaging with a data acquisition time of less than a minute without averaging, which was limited by the repetition rate of the laser.

Diffusion Tensor Imaging and 3D Tractography of the Cervical Spinal Cord Using the ECG-Gated Line-Scan Technique

2007 ◽  
Vol 20 (5) ◽  
pp. 574-579 ◽  
Author(s):  
M. Hori ◽  
K. Ishigame ◽  
S. Aoki ◽  
H. Kumagai ◽  
T. Araki
Keyword(s):  
Spinal Cord ◽  
Clinical Symptoms ◽  
Diffusion Tensor ◽  
Cervical Spinal Cord ◽  
Three Dimensional ◽  
Acquisition Time ◽  
Clinical Use ◽  
Ecg Gating ◽  
Line Scan

Diffusion tensor (DT) magnetic resonance (MR) imaging in addition to conventional MR images provide valuable information on the brain. This study compared line scan DT imaging with and without the ECG-gating technique to estimate clinical usefulness of the line scan diffusion tensor image (LSDTI) with ECG-gating in evaluating spinal cord diseases in vivo. First, five healthy volunteers participated in the comparison study. LSDWI was performed in three to five sagittal sections with a pulsed-field-gradient diffusion preparation pulse employing two different b-values (0 and 700 s/mm2) along six directions. Apparent diffusion coefficient (ADC) maps and fractional anisotropy (FA) were calculated and three-dimensional tract reconstruction and color schemes of the spinal cord were obtained. Image quality and the acquisition time of each LSDTI were compared. Second, LSDTI with ECG-gating was performed in eighteen patients with cervical spinal cord disorders and evaluated by two neuroradiologists. Images with the ECG-gated technique were all superior to those without ECG—gating. Mean extended time for LSDTI with ECG-gating was approximately two minutes. In clinical use, the ADC and FA of spinal cord in patients with cervical spondylotic myelopathy statically changed. Moreover, demonstration of fibers was correlated with clinical symptoms. ECG-gating technique is preferable to LSDTI. The ADC and FA measurements and 3D fiber tracking of LSDTI with ECG-gating are promising methods to estimate cervical spinal cord pathology in clinical use.

scholarly journals Reconstruction for Limited-Projection Fluorescence Molecular Tomography Based on a Double-Mesh Strategy

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Huangjian Yi ◽  
Xu Zhang ◽  
Jinye Peng ◽  
Fengjun Zhao ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Small Animal ◽  
Initial Result ◽  
Acquisition Time ◽  
Feasible Region ◽  
Fluorescence Molecular Tomography ◽  
Fluorescence Measurements ◽  
Region Extraction ◽  
Data Acquisition Time

Limited-projection fluorescence molecular tomography (FMT) has short data acquisition time that allows fast resolving of the three-dimensional visualization of fluorophore within small animal in vivo. However, limited-projection FMT reconstruction suffers from severe ill-posedness because only limited projections are used for reconstruction. To alleviate the ill-posedness, a feasible region extraction strategy based on a double mesh is presented for limited-projection FMT. First, an initial result is rapidly recovered using a coarse discretization mesh. Then, the reconstructed fluorophore area in the initial result is selected as a feasible region to guide the reconstruction using a fine discretization mesh. Simulation experiments on a digital mouse and small animal experiment in vivo are performed to validate the proposed strategy. It demonstrates that the presented strategy provides a good distribution of fluorophore with limited projections of fluorescence measurements. Hence, it is suitable for reconstruction of limited-projection FMT.

Enhancement of Reconstruction Accuracy of the HELS Method

2002 ◽  
Author(s):  
Tatiana Semenova ◽  
Sean F. Wu
Keyword(s):  
Acoustic Field ◽  
Matrix Equation ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Back Propagation ◽  
Three Dimensional ◽  
Constrained Minimization ◽  
Reconstruction Accuracy ◽  
New Strategy ◽  
Reconstruction Point

The validity of the HELS method (Wu, 2000) for reconstructing the acoustic pressure field inside the minimum circle that encloses an arbitrary object is examined. Results show that the HELS solutions are approximate and the corresponding matrix equation is ill conditioned in general for back propagation of the acoustic field. Accordingly, the further the reconstruction point moves inside the minimum circle, the worse the reconstruction accuracy becomes. To overcome this difficulty new strategy for sensor placement is proposed. This strategy together with a constrained minimization are shown to yield satisfactory reconstruction inside the minimum circle. The same procedures can be extended to three-dimensional problems.

scholarly journals Review of methods to improve the performance of linear array-based photoacoustic tomography

2019 ◽  
Vol 13 (02) ◽  
pp. 2030003 ◽  
Author(s):  
Yuehang Wang ◽  
Ye Zhan ◽  
Melinda Tiao ◽  
Jun Xia
Keyword(s):  
Linear Array ◽  
Imaging System ◽  
Imaging Modality ◽  
Low Cost ◽  
Three Dimensional ◽  
Optical Excitation ◽  
Recent Decade ◽  
Photoacoustic Tomography ◽  
Light Illumination ◽  
Geometrical Shape

As a hybrid imaging modality that combines optical excitation with acoustic detection, photoacoustic tomography (PAT) has become one of the fastest growing biomedical imaging modalities. Among various types of transducer arrays used in a PAT system configuration, the linear array is the most commonly utilized due to its convenience and low-cost. Although linear array-based PAT has been quickly developed within the recent decade, there are still two major challenges that impair the overall performance of the PAT imaging system. The first challenge is that the three-dimensional (3D) imaging capability of a linear array is limited due to its poor elevational resolution. The other challenge is that the geometrical shape of the linear array constrains light illumination. To date, substantial efforts have been made to address the aforementioned challenges. This review will present current technologies for improving the elevation resolution and light delivery of linear array-based PAT systems.

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