A simultaneous PET/MRI breast scanner based on the RatCAP

Background: This study aimed to test the possibility of using Magnetic Resonance (MR) images to create anthropomorphic breast phantoms for X-ray imaging and to compare the performance of fused deposition modeling (FDM) and 2D inkjet printing with radiopaque inks. Materials and Methods: Two physical phantoms were produced using either an inkjet printer on paper or an FDM technique, both based on clinical MR data. The paper phantom was printed with 1.2 g of KI dissolved in 20 ml of water. For the FDM phantom, the extrusion rate was adjusted according to clinical Hounsfield unit (HU) values. These phantoms underwent imaging using a clinical computed tomography (CT) device at two energy spectra, and their CT images were assessed in terms of HUs, histogram distributions, spectral and subjective analyses, as well as cost. The objective CT analysis of the phantoms revealed that HU values and β-values, indicating the anatomical complexity of the breast parenchyma, were in line with those expected, with an advantage for the FDM-based phantom. In both cases, the β-values were close to those for clinical breast images acquired with highresolution CT scanners. Subjective evaluation, however, indicated a need for refining the realism of the phantoms, particularly in terms of preserving the fine details. Conclusion: Breast MR Images offer the possibility of constructing breast phantoms. However, the method fails to replicate fine details in phantom CT images. Addressing this challenge requires improvement in segmentation processes and manufacturing accuracy.

New high spatial resolution positron emission tomography (PET) detectors for small animal and breast imaging have been developed. In these detectors, position-sensitive photomultipliers (R7600-C12) and dual-layer pixelated bismuth germanate (BGO) crystals are employed to detect and localize gamma rays. Modified high-voltage dividers with last dynode readout circuits, front-end anode position, and last dynode timing schemes have been investigated and developed for these detectors. Methods for combining four position-sensitive photomultipliers (PS-PMTs) with simple four (X/sup -/, X/sup +/, Y/sup -/, and Y/sup +/) outputs have been developed to further simplify the position processing. The front-end circuits are small so they can be fitted into the detector's structure. A prototype of two detector modules, each having two PS-PMTs with corresponding electronic circuits, has been built for evaluation. The crystal elements of 10/spl times/10 in the proximal layer and 9/spl times/9 in the distal can be clearly identified.

A program of work has been undertaken using Monte Carlo simulations and experimental measurements with the RPET scanner to evaluate the role of a dedicated high resolution positron camera for breast imaging. The simulated detector consists of 20 mm long crystals arranged in a ring of diameter 220 mm by 52 mm long. The sides of the crystal faces were varied from 1 mm to 4.5 mm. The breast was simulated by a cylinder 69 mm in diameter by 65 mm long containing a lesion varying from 2 mm to 10 mm in diameter with an SUV in the range 2-8. The number of simulated counts varied from 1-10 million. Preliminary measurements with the RPET camera have also been made using the same size phantom/lesion combination. After these measurements are completed it is hoped to evaluate a hybrid photo diode detector for its usefulness as a dedicated PET breast scanner. The simulations show that a 4 mm diameter lesion with an SUV of 6 (typical of measured values) can be detected with 1 million acquired counts using 2.5 mm crystals. The detection of smaller lesions is severely limited by sensitivity. Using smaller crystals does not help detect smaller lesions but increasing acquired counts does. Experimental measurements show the importance of minimising the background from the heart.

Count rate studies of a box-shaped PET breast imaging system comprised of position sensitive avalanche photodiodes utilizing monte carlo simulation

We are currently developing a small animal positron emission tomography (PET) scanner with a design goal of 1 microlitre (1 mm3) image resolution. The detectors consist of a 12 × 12 array of 1 × 1 × 10 mm lutetium oxyorthosilicate (LSO) scintillator crystals coupled to a 64-channel photomultiplier tube (PMT) via 5 cm long optical fibre bundles. The optical fibre connection allows a high detector packing fraction despite the dead space surrounding the active region of the PMT. Optical fibre bundles made from different types of glass were tested for light transmission, and also their effects on crystal identification and energy resolution, and compared to direct coupling of the LSO arrays to the PMTs. We also investigated the effects of extramural absorber (EMA) in the fibre bundles. Based on these results, fibre bundles manufactured from F2 glass were selected. We built three pairs of prototype detectors (directly coupled LSO array, fibre bundle without EMA and fibre bundle with EMA) and measured flood histograms, energy resolution, intrinsic spatial resolution and timing resolution. The results demonstrated an intrinsic spatial resolution (FWHM) of 1.12 mm (directly coupled), 1.23 mm (fibre bundle without EMA coupling) and 1.27 mm (fibre bundle with EMA coupling) using an approximately 500 μm diameter Na-22 point source. Using a 330 μm outer diameter steel needle line source filled with F-18, spatial resolution for the detector with the EMA optical fibre bundle improved to 1.05 mm. The respective timing and energy FWHM values were 1.96 ns, 21% (directly coupled), 2.20 ns, 23% (fibre bundle without EMA) and 2.99 ns, 30% (fibre bundle with EMA). The peak-to-valley ratio in the flood histograms was better with EMA (5:1) compared to the optical fibre bundle without EMA (2.5:1), due to the decreased optical cross-talk. In comparison to the detectors used in our current generation microPET scanner, these detectors substantially improve on the spatial resolution, preserve the timing resolution and provide adequate energy resolution for a modern high-resolution animal PET tomograph.

A three-dimensional modeling method for quantitative photoacoustic breast imaging with handheld probe

The high incidence of breast cancer in women has increased significantly in the recent years. Breast MRI involves the use of magnetic resonance imaging to look specifically at the breast. Contrast-enhanced breast MRIs acquired by contrast injection have been shown to be very sensitive in the detection of breast cancer, but are also time-consuming and cause waste of medical resources. This paper utilizes the use of type-II fuzzy sets to enhance the contrast of the breast MRI image. To evaluate the performance of our approach, we run tests over different MRI breast images and show that the overall accuracy offered by the employed approach is high.KeywordsBreast CancerMagnetic Resonance ImagingMembership FunctionSpike Neural NetworkBreast MRIsThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper studies induced electric fields and current densities for peripheral nerve stimulation (PNS) induced by breast gradient coils. The numerical calculations are based on an efficient, quasi-static, finite-difference (QSFD) scheme. The application of the human body to the calculations of induced current densities and electric fields from applied low frequency magnetic and electric fields is described. The spatial distributions of the induced electric field and their gradients are calculated. This study provides some insight into the spatial characteristics of the induced field gradients for PNS in MRI, which may be used to further evaluate the sites where magnetic stimulation is likely to occur and to optimize gradient coil design.

For women with dense breast tissue, who are at much higher risk for developing breast cancer, the performance of mammography is at its worst. Consequently, many early cancers go undetected when they are the most treatable. Improved cancer detection for women with dense breasts would decrease the proportion of breast cancers diagnosed at later stages, which would significantly lower the mortality rate. The emergence of whole breast ultrasound provides good performance for women with dense breast tissue, and may eliminate the current trade-off between the cost effectiveness of mammography and the imaging performance of more expensive systems such as magnetic resonance imaging. We report on the performance of SoftVue, a whole breast ultrasound imaging system, based on the principles of ultrasound tomography. SoftVue was developed by Delphinus Medical Technologies and builds on an early prototype developed at the Karmanos Cancer Institute. We present results from preliminary testing of the SoftVue system, performed both in the lab and in the clinic. These tests aimed to validate the expected improvements in image performance. Initial qualitative analyses showed major improvements in image quality, thereby validating the new imaging system design. Specifically, SoftVue's imaging performance was consistent across all breast density categories and had much better resolution and contrast. The implications of these results for clinical breast imaging are discussed and future work is described.

National DRLs for adult body CT scans based on body width

: Early efforts to produce decision aids, although they led to valuable research findings, did not succeed as field applications. Even when the targeted users agreed that the computer-aided decision process did improve decision making, these aids eventually fell into disuse when the personal support of the decision analysts was removed. User attitudes tended to be dominated by the short-range considerations of speed, convenience, and simplicity of operation, rather than by the long-range factors such as methodological thoroughness and consistency. The primary goal of this research project was to develop a prototype version of a user-friendly decision aid which could be used by persons with little or no prior training. This decision aid was not only designed to be easy to use, but also to save time and fit into the user's office or field site, while still providing the benefits of a technically sound decision-analytic approach. Since then, a prototype system has been developed, and a working model has been delivered to DARPA. This report is intended to accompany that working model. Its function is to document the purpose of the research effort, the technical approach, accomplishments of the project, and the prognosis for future development based on lessons learned during the effort. Because of the aid's self-explanatory nature and its unique hardware configuration, neither a users guide nor a system manual is needed.

Mammography has served the population of women who are at-risk for breast cancer well over the past 30 years. While mammography has undergone a number of changes as digital detector technology has advanced, other modalities such as computed tomography have experienced technological sophistication over this same time frame as well. The advent of large field of view flat panel detector systems enable the development of breast CT and several other niche CT applications, which rely on cone beam geometry. The breast, it turns out, is well suited to cone beam CT imaging because the lack of bones reduces artifacts, and the natural tapering of the breast anteriorly reduces the x-ray path lengths through the breast at large cone angle, reducing cone beam artifacts as well. We are in the process of designing a third prototype system which will enable the use of breast CT for image guided interventional procedures. This system will have several copies fabricated so that several breast CT scanners can be used in a multi-institutional clinical trial to better understand the role that this technology can bring to breast imaging.

Motivation: The quantity and cost limitations of clinical MRI scanners restrict the widespread availability of breast MRI in breast disease screening. Goal(s): Our goal was to show it is possible to construct a portable breast MRI scanner for point-of-care scenarios. Approach: A racetrack-shaped double-pole magnet was designed with the weight below 850 kg. Custom-built gradient coils, RF coils and active EMI strategy were integrated and tested on in vivo. Results: In vivo breast images were acquired with 1.56×1.56×10 mm3 resolution in 4 minutes to show the applicability of the system for routine breast disease screening. Impact: The constructed 50 mT portable breast MRI prototype has the potential to be used in early screening of breast disease in the future.

Tissue displacements required for mechanical property reconstruction in magnetic resonance elastography (MRE) are acquired in a magnetic resonance imaging (MRI) scanner, therefore, anatomical information is available from other imaging sequences. Despite its availability, few attempts to incorporate prior spatial information in the MRE reconstruction process have been reported. This paper implements and evaluates soft prior regularization (SPR), through which homogeneity in predefined spatial regions is enforced by a penalty term in a nonlinear inversion strategy. Phantom experiments and simulations show that when predefined regions are spatially accurate, recovered property values are stable for SPR weighting factors spanning several orders of magnitude, whereas inaccurate segmentation results in bias in the reconstructed properties that can be mitigated through proper choice of regularization weighting. The method was evaluated in vivo by estimating viscoelastic mechanical properties of frontal lobe gray and white matter for five repeated scans of a healthy volunteer. Segmentations of each tissue type were generated using automated software, and statistically significant differences between frontal lobe gray and white matter were found for both the storage modulus and loss modulus . Provided homogeneous property assumptions are reasonable, SPR produces accurate quantitative property estimates for tissue structures which are finer than the resolution currently achievable with fully distributed MRE.

Extracting tumor in MR brain and breast image with Kapur’s entropy based Cuckoo Search Optimization and morphological reconstruction filters