Biomedical Spectroscopy and Imaging - Volume 8, issue 1-2

Authors: El-Shenawee, Magda | Vohra, Nagma | Bowman, Tyler | Bailey, Keith

Article Type: Review Article

Abstract: Terahertz imaging and spectroscopy has demonstrated a potential for differentiating tissue types of excised breast cancer tumors. Pulsed terahertz technology provides a broadband frequency range from 0.1 THz to 4 THz for detecting cancerous tissue. Tumor tissue types of interest include cancer typically manifested as infiltrating ductal or lobular carcinomas, fibro-glandular (healthy connective tissues) and fat. In this work, images of breast tumors excised from human and animal models are reviewed. In addition to alternate fresh tissues, breast cancer tissue phantoms are developed to further evaluate terahertz imaging and the potential use of contrast agents. Terahertz results are successfully validated with pathology …images, showing strong differentiation between cancerous and healthy tissues for all freshly excised tissues and types. The advantages, challenges and limitations of THz imaging of breast cancer are discussed. Show more

Keywords: Breast cancer, terahertz imaging, terahertz spectroscopy, margin assessment, lumpectomy

DOI: 10.3233/BSI-190187

Citation: Biomedical Spectroscopy and Imaging, vol. 8, no. 1-2, pp. 1-9, 2019

Authors: Knight, Michael J. | Damion, Robin A. | McGarry, Bryony L. | Bosnell, Rose | Jokivarsi, Kimmo T. | Gröhn, Olli H.J. | Jezzard, Peter | Harston, George W.J. | Carone, Davide | Kennedy, James | El-Tawil, Salwa | Elliot, Jennifer | Muir, Keith W. | Clatworthy, Philip | Kauppinen, Risto A.

Article Type: Research Article

Abstract: Background and objective: In hyperacute ischaemic stroke, T2 of cerebral water increases with time. Quantifying this change may be informative of the extent of tissue damage and onset time. Our objective was to develop a user-unbiased method to measure the effect of cerebral ischaemia on T2 to study stroke onset time-dependency in human acute stroke lesions. Methods: Six rats were subjected to permanent middle cerebral occlusion to induce focal ischaemia, and a consecutive cohort of acute stroke patients (n = 38 ) were recruited within 9 hours from symptom onset. T1-weighted structural, T2 relaxometry, and diffusion …MRI for apparent diffusion coefficient (ADC) were acquired. Ischaemic lesions were defined as regions of lowered ADC. The median T2 difference (ΔT2) between lesion and contralateral non-ischaemic control region was determined by the newly-developed spherical reference method, and data compared to that obtained by the mirror reference method. Linear regressions and receiver operating characteristics (ROC) were compared between the two methods. Results: ΔT2 increases linearly in rat brain ischaemia by 1.9 ± 0.8 ms/h during the first 6 hours, as determined by the spherical reference method. In patients, ΔT2 linearly increases by 1.6 ± 1.4 and 1.9 ± 0.9 ms/h in the lesion, as determined by the mirror reference and spherical reference method, respectively. ROC analyses produced areas under the curve of 0.83 and 0.71 for the spherical and mirror reference methods, respectively. Conclusions: Data from the spherical reference method showed that the median T2 increase in the ischaemic lesion is correlated with stroke onset time in a rat as well as in a human patient cohort, opening the possibility of using the approach as a timing tool in clinics. Show more

Keywords: T2 relaxation time, diffusion MRI, stroke onset time, acute ischaemic stroke

DOI: 10.3233/BSI-190185

Citation: Biomedical Spectroscopy and Imaging, vol. 8, no. 1-2, pp. 11-28, 2019

Authors: Ghani, Muhammad U. | Gregory, Bradley | Omoumi, Farid | Zheng, Bin | Yan, Aimin | Wu, Xizeng | Liu, Hong

Article Type: Research Article

Abstract: A single-projection based phase retrieval method based on the phase attenuation duality principle (PAD) was used to compare the spatial resolution of the acquired phase sensitive and PAD processed phase retrieved images. An inline phase sensitive prototype was used to acquire the phase sensitive images. The prototype incorporates a micro-focus x-ray source and a flat panel detector with a 50 μ m pixel pitch. A phantom composed of a 2 cm thick 50–50 adipose-glandular mimicking slab sandwiched with a 0.82 cm thick slanted PMMA sharp edge was used. Phase sensitive image of the phantom was acquired at 120 kV, 3.35 mAs with a 16 μ …m tube focal spot size under a geometric magnification (M) of 2.5. The PAD based method was applied to the acquired phase sensitive image for the retrieval of phase values. With necessary data processing, modulation transfer function (MTF) curves were determined for the estimation and comparison of the spatial resolution. The PAD processed phase retrieved values of the phantom were in good agreement with the theoretically calculated values. Phase sensitive images showed higher spatial resolution at all spatial frequencies compared to the phase retrieved images. It was noted that the high-frequency signal components in the retrieved image were suppressed that resulted in lower MTF values. When compared to the phase sensitive image, the cutoff resolution (10% MTF) for phase retrieved image dropped 32% from 15.6 lp/mm (32 μ m) to 10.6 lp/mm (47 μ m). The resolution offered by this phase sensitive prototype is radiographically enough to detect breast cancer. Show more

Keywords: Phase retrieval, high-energy phase contrast imaging, spatial resolution

DOI: 10.3233/BSI-190186

Citation: Biomedical Spectroscopy and Imaging, vol. 8, no. 1-2, pp. 29-40, 2019

Authors: González, Francisco Javier | González, Raymundo | López, Juan Carlos

Article Type: Research Article

Abstract: The use of steady state thermal patterns in breast cancer screening have shown low specificities, it is believed that by thermally exciting the body with a cold stimulus the temperature contrast will increase as well as the specificity of the technique. In this work computer thermal simulations of breasts subjected to a cold stress and at steady state were performed on a real scanned human female model in order to evaluate the advantages of using active dynamic thermography over steady state thermography. Results show that there is an increase in contrast when performing active dynamic thermography compared to steady state …thermography but only in the case of tumors that are close to the surface of the skin. It was also found that the morphology of the torso and breasts appears to play a role in the sensitivity of thermal measurements needed for tumor detection. Show more

Keywords: Breast thermography, finite element simulations, active dynamic infrared thermography

DOI: 10.3233/BSI-190188

Citation: Biomedical Spectroscopy and Imaging, vol. 8, no. 1-2, pp. 41-45, 2019