Sensitivity study of an ultrasound coupled transrectal electrical impedance tomography system for prostate imaging

Wan, Yuqing; Halter, Ryan J.; Borsic, Andrea; Manwaring, Preston; Hartov, Alex; Paulsen, Keith D.

doi:10.1088/0967-3334/31/8/s02

Cited by 31 publications

(30 citation statements)

References 14 publications

(20 reference statements)

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“…The reconstruction successfully identifies the position of the metal ball and shows minor artifacts, smaller than those in the simulations, in part because the contrast of the inclusion is stronger. This example, coupled with those presented in Wan et al (2010) demonstrate that it is possible to use the developed prostate EIT probe to successfully image the conductivity in a three-dimensional volume in front of the probe.…”

Section: Image Reconstruction Resultsmentioning

confidence: 72%

“…The combined EIT and US probe we use consists of a 2.28 cm shaft, which houses internally an US head that is mechanically translated and rotated inside the shaft to acquire a three-dimensional imaging volume (Wan et al 2010). An array of 30 EIT electrodes is printed on a flexible substrate and attached to the surface of the probe.…”

Section: Reconstruction Algorithmmentioning

confidence: 99%

“…The transrectal probe we developed, described in Borsic et al (2009) and in Wan et al (2010), is based on a commercial transrectal ultrasound probe to which a set of 30 electrodes has been applied, as an EIT sensing array. Electrodes are printed on a flexible substrate, which is attached to the surface of the probe, and are arranged such that an ‘acoustic window’ is open to ultrasonic energy transmission (see figure 1).…”

Section: Introductionmentioning

confidence: 99%

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Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate

et al. 2010

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Transrectal electrical impedance tomography (TREIT) has been proposed as an adjunct modality for enhancing standard clinical ultrasound (US) imaging of the prostate. The proposed TREIT probe has an array of electrodes adhered to the surface of a cylindrical US probe that is introduced inside of the imaging volume. Reconstructing TREIT images in the open-domain geometry established with this technique poses additional challenges to those encountered with closeddomain geometries, present in more conventional EIT systems, because of the rapidly decaying current densities at increasing distances from the probe surface. We developed a finite element method (FEM)-based dual-mesh reconstruction algorithm which employs an interpolation scheme for linking a fine forward mesh with a coarse grid of pixels, used for conductivity estimation. Simulation studies using the developed algorithm demonstrate the feasibility of imaging moderately contrasting inclusions at distances of three times the probe radius from the probe surface and at multiple angles about the probe's axis. The large, dense FEM meshes used here require significant computational effort. We have optimized our reconstruction algorithm with multi-core processing hardware and efficient parallelized computational software packages to achieve a speedup of 9.3 times when compared to a more traditional Matlab-based, single CPU solution. The simulation findings and computational optimization provide a state-of-the-art reconstruction platform for use in further evaluating transrectal electrical impedance tomography.

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Section: Image Reconstruction Resultsmentioning

confidence: 72%

Section: Reconstruction Algorithmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate

et al. 2010

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“…Electrical impedance tomography (EIT), which has been commonly used to reconstruct cross-sectional images of resistivity distribution inside human body (Abascal et al 2011, Solà et al 2011), could be possibly utilized for prostate cancer detection. Considering the fact that the prostate is located deep within the pelvis and surrounded by complicated tissues, EIT techniques with endo-electrode arrays have been developed specifically for prostate imaging in order to make the injected current more easily reach the imaging target (Jossinet et al 2002, 2004, 2006, Borsic et al 2009b, 2010 and Wan et al 2010). A probe printed with an electrode array is inserted into the human body through the urethra or rectum in order to reach as close to the prostate as possible.…”

Section: Introductionmentioning

confidence: 99%

A feasibility study of magnetic resonance electrical impedance tomography for prostate cancer detection

Liu

Zhang

2014

Physiol. Meas.

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Magnetic resonance electrical impedance tomography (MREIT) is an imaging technique that reconstructs the conductivity distribution inside the subject using magnetic flux density or current density measurements acquired by a magnetic resonance imaging (MRI) system. Since the primary prostate cancer diagnostic method, prostate biopsy, has limited accuracy in cancer diagnosis and malignant tissues have shown significantly different electrical properties from normal or benign tissues, MREIT has potential application in prostate cancer detection. The feasibility of utilizing MREIT in detecting prostate cancer was evaluated via a series of well-designed computer simulations in the present study. MREIT techniques with three different electrode configurations (external, trans-rectal, and trans-urethral electrode arrays) and two different reconstruction algorithms (J-substitution algorithm and harmonic Bz algorithm) were successfully developed. The performance of different MREIT techniques were evaluated and compared based on the imaging accuracy of the reconstructed conductivity distribution in the prostate. Without the presence of noise, the external MREIT achieves a better imaging accuracy than the two endo-MREIT (trans-rectal and trans-urethral) techniques, while the trans-urethral MREIT achieves the best imaging accuracy in noisy environments. We also found that the J-substitution reconstruction algorithm consistently offered better imaging accuracy than the harmonic Bz algorithm. When Gaussian distributed random noise with a standard deviation of 0.25 nT was added, the relative errors (RE) between the reconstructed and target conductivity distributions inside the prostate were observed to be 14.18% and 17.35% by the trans-urethral MREIT with the J-substitution and harmonic Bz algorithms respectively. The lower REs of 9.64% and 11.17% were achieved respectively when the standard deviation of noise was reduced to 0.05 nT. The simulation results demonstrate the feasibility of applying MREIT for prostate cancer detection.

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“…The electrodes appear as reflections on the periphery of the ultrasound images and are used to co-register US and EIT images. The flexible circuit of electrodes is wired to a custom 32 channel data acquisition system controlled through a LabView programming environment; a complete description of the system can be found in Wan et al 2010 and Borsic et al 2010. The probe is mounted on a rigid, articulated arm that locks the probe in place to ensure stable positioning during data acquisition.…”

Section: Introductionmentioning

confidence: 99%

Anatomically accurate hard priors for transrectal electrical impedance tomography (TREIT) of the prostate

et al. 2012

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Current prostate biopsy procedures entail sampling tissues at template-based locations that are not patient specific. Ultrasound (US) coupled Transrectal Electrical Impedance Tomography (TREIT), featuring an endorectal US probe retrofitted with electrodes, has been developed for prostate imaging. This multi-modal imaging system aims to identify suspicious tumor regions based on their electrical properties and ultimately provide additional patient-specific locations where to take biopsy samples. Unfortunately, the open-domain geometry associated with TREIT results in a severely ill-posed problem due to the small number of measurements and unbounded imaging domain. Furthermore, reconstructing contrasts within the prostate volume is challenging because the conductivity differences between the prostate and surrounding tissues are much larger than the conductivity differences between benign and malignant tissues within the prostate. To help overcome these problems, anatomically accurate hard priors can be employed to limit estimation of the electrical property distribution to within the prostate volume; however, this requires the availability of structural information. Here, a method that extracts the prostate surface from US images and incorporates this surface into the image reconstruction algorithm has been developed to enable estimation of electrical parameters within the prostate volume. In this paper, the performance of this algorithm is evaluated against a more traditional EIT algorithm that does not use anatomically accurate structural information, in the context of numerical simulations and phantom experiments. The developed anatomically accurate hard-prior algorithm demonstrably identifies contrasts within the prostate volume while an algorithm that does not rely on anatomically accurate structural information is unable to localize these contrasts. While inclusions are identified in the correct locations, they are found to be smaller in size than the actual object due to the rapid decay in sensitivity at increasing distances from the probe surface. Despite this, identifying the size of the inclusion accurately may not be essential for biopsy guidance in a clinical setting; instead, knowledge of the general vicinity of a cancerous lesion may be sufficient for suggesting and guiding clinicians to extract additional biopsy cores.

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Sensitivity study of an ultrasound coupled transrectal electrical impedance tomography system for prostate imaging

Cited by 31 publications

References 14 publications

Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate

Electrical impedance tomography reconstruction for three-dimensional imaging of the prostate

A feasibility study of magnetic resonance electrical impedance tomography for prostate cancer detection

Anatomically accurate hard priors for transrectal electrical impedance tomography (TREIT) of the prostate

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