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Alles E.,Cancer Imaging Center | Harris-Birtill D.,Cancer Imaging Center | Harris-Birtill D.,Imperial College London | Jaeger M.,University of Bern | Bamber J.,Cancer Imaging Center
IEEE International Ultrasonics Symposium, IUS | Year: 2013

A clinical spectroscopic eiphotoacoustic scanner is presented, evaluated and optimised. The scanner combines a clinical ultrasound scanner with commercially available lasers to generate photocoustic images that are inherently coregistered with the ultrasound images and can be acquired by freehand scanning. Arrays of graphite rods are used to determine the point spread function (PSF, signal-to-nose (SNR and signal-to-clutter ratios (SCR) of the system and optimise the image quality by varying the illumination geometry. At a distance of 26 mm, mall spatial PSF extents are found (lateral 399 ± 80 μm, axial 340 ± 20 μm, elevational 1.43 ± 0.26 mm) and hence a high solution is obtained. Due to the strong optical scattering in biological tissue, the illumination geometry has virtually no effect on the image intensity, SNR and SCR, and hence practicality is the main concern when designing the clinical scan-head geometry. © 2013 IEEE.

Rata M.,Cancer Research UK Research Institute | Collins D.J.,Cancer Research UK Research Institute | Darcy J.,Cancer Research UK Research Institute | Messiou C.,Cancer Research UK Research Institute | And 6 more authors.
European Radiology | Year: 2016

Objectives: Pharmacokinetic (PK) modelling of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data requires a reliable measure of the arterial input function (AIF) to robustly characterise tumour vascular properties. This study compared repeatability and treatment-response effects of DCE-MRI-derived PK parameters using a population-averaged AIF and three patient-specific AIFs derived from pre-bolus MRI, DCE-MRI and dynamic contrast computed tomography (DC-CT) data. Methods: The four approaches were compared in 13 patients with abdominal metastases. Baseline repeatability [Bland-Altman statistics; coefficient of variation (CoV)], cohort percentage change and p value (paired t test) and number of patients with significant DCE-MRI parameter change post-treatment (limits of agreement) were assessed. Results: Individual AIFs were obtained for all 13 patients with pre-bolus MRI and DC-CT-derived AIFs, but only 10/13 patients had AIFs measurable from DCE-MRI data. The best CoV (7.5 %) of the transfer coefficient between blood plasma and extravascular extracellular space (Ktrans) was obtained using a population-averaged AIF. All four AIF methods detected significant treatment changes: the most significant was the DC-CT-derived AIF. The population-based AIF was similar to or better than the pre-bolus and DCE-MRI-derived AIFs. Conclusions: A population-based AIF is the recommended approach for measuring cohort and individual effects since it has the best repeatability and none of the PK parameters derived using measured AIFs demonstrated an improvement in treatment sensitivity. Key Points: • Pharmacokinetic modelling of DCE-MRI data requires a reliable measure of AIF. • Individual MRI-DCE-derived AIFs cannot reliably be extracted from patients. • All four AIF methods detected significant Ktranschanges after treatment. • A population-based AIF can be recommended for measuring cohort treatment responses in trials. © 2015, The Author(s).

Joseph J.,University of Cambridge | Joseph J.,Cancer Imaging Center | Tomaszewski M.,University of Cambridge | Tomaszewski M.,Cancer Imaging Center | And 3 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015

MultiSpectral Optoacoustic Tomography (MSOT) is an emerging modality that combines the high contrast of optical imaging with the spatial resolution and penetration depth of ultrasound, to provide detailed images of hemoglobin concentration and oxygenation. To facilitate accurate determination of changes in the vascularity and oxygenation of a biological tissue over time, for example, a tumor in response to cancer therapy, an extensive study of stability and reproducibility of a small animal MSOT system has been performed. Investigations were first made with a stable phantom imaged repeatedly over time scales of hours, days and months, to evaluate the reproducibility of the system over time. We found that the small animal MSOT system exhibited excellent reproducibility with a coefficient of variation (COV) in the measured MSOT signals of less than 8% over the course of 30 days and within 1.5% over a single day. Experiments performed in vivo demonstrated the potential for measurement of oxyhemoglobin over time in a realistic experimental setting. The effect of breathing medical air or oxygen under conditions of fixed respiration rate and body temperature within normal organs, including the spleen and kidneys, were investigated. The COV for oxyhemoglobin signals retrieved from spectral unmixing was assessed within both biological (different mouse) and imaging (different scan) replicates. As expected, biological replicates produced a large COV (up to 40% within the spleen) compared to imaging replicates within a single mouse (up to 10% within the spleen). Furthermore, no significant difference was found between data acquired by different operators. The data presented here suggest that MSOT is highly reproducible for both phantom and in vivo imaging, hence could reliably detect changes in oxygenation occurring in living subjects. © 2015 SPIE.

Kim J.S.,Biterials Co | Kim Y.-H.,Seoul National University | Kim Y.-H.,Cancer Research Institute | Kim J.H.,Biterials Co | And 16 more authors.
Nanomedicine | Year: 2012

Aim: To monitor cells in vivo or to detect the sentinel lymph node, we developed a PET/MRI silica nanoprobe with an enhanced near-infrared fluorescence signal. Methods: We developed enhanced near-infrared fluorescent (NIRF) magnetic silica nanoparticles, MNP-SiO 2(NIR797), that encapsulate NIRF dye in the silica. We applied this probe to visualizing cells in the deep tissue of mice using NIRF imaging. After labeling with a radioisotope, 68Ga, on the surface of MNP-SiO 2(NIR797), we injected it into the forepaw of mice to visualize the sentinel lymph node. Results: This encapsulated nanoprobe showed enhancement of fluorescent intensity and stability compared with the nanoprobe, which had the same dyes on the surface of the silica nanoparticles. We also obtained multimodal in vivo imaging of 68Ga-{MNP-SiO 2(NIR797)} applied to sentinel lymph node detection of mice using PET/MRI/NIRF images. Conclusion: This multimodal nanoprobe with enhanced fluorescence may provide a useful tool for imaging diagnostics and cell tracking. © 2012 Future Medicine Ltd.

Alonzi R.,Marie Curie Research Wing | Alonzi R.,Mount Vernon Cancer Center | Padhani A.R.,Paul Strickland Scanner Center | Taylor N.J.,Paul Strickland Scanner Center | And 5 more authors.
International Journal of Radiation Oncology Biology Physics | Year: 2011

Purpose: The antivascular effects of androgen deprivation have been investigated in animal models; however, there has been minimal investigation in human prostate cancer. This study tested the hypothesis that androgen deprivation causes significant reductions in human prostate tumor blood flow and the induction of hypoxia at a magnitude and in a time scale relevant to the neoadjuvant setting before radiotherapy. Methods and Materials: Twenty patients were examined, each with five multi-parameter magnetic resonance imaging scans: two scans before the commencement of androgen suppression, one scan after 1 month of hormone treatment, and two further scans after 3 months of therapy. Quantitative parametric maps of the prostate informing on relative blood flow (rBF), relative blood volume (rBV), vascular permeability (transfer constant [Ktrans]), leakage space (ve) and blood oxygenation (intrinsic relaxivity [R2]) were calculated. Results: Tumor blood volume and blood flow decreased by 83% and 79%, respectively, in the first month (p < 0.0001), with 74% of patients showing significant changes. The proportion of individual patients who achieved significant changes in T1 kinetic parameter values after 3 months of androgen deprivation for tumor measurements was 68% for Ktrans and 53% for ve By 3 months, significant increases in R2 had occurred in prostate tumor, with a rise of 41.1% (p < 0.0001). Conclusions: Androgen deprivation induces profound vascular collapse within 1 month of starting treatment. Increased R2 in regions of prostate cancer and a decrease in blood volume suggest a reduction in tumor oxygenation. © 2011 Elsevier Inc.

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