We report and discuss clinical breast imaging results obtained with operator independent ultrasound tomography. A
series of breast exams are carried out using a recently upgraded clinical prototype designed and built on the principles of
ultrasound tomography. The in-vivo performance of the prototype is assessed by imaging patients at the Karmanos
Cancer Institute. Our techniques successfully demonstrate in-vivo tomographic imaging of breast architecture in both
reflection and transmission imaging modes. These initial results indicate that operator-independent whole-breast imaging
and the detection of cancerous breast masses are feasible using ultrasound tomography techniques. This approach has
the potential to provide a low cost, non-invasive, and non-ionizing means of evaluating breast masses. Future work will
concentrate on extending these results to larger trials.
A novel clinical prototype, CURE (Computed Ultrasound Risk Evaluation), is used to collect breast tissue image data of
patients with either benign or malignant masses. Three types of images, reflection, sound speed and attenuation, are
generated from the raw data using tomographic reconstruction algorithms. Each type of image, usually presented as a
gray scale image, maps different characteristics of the breast tissue. This study is focused on fusing all three types of
images to create true color (RGB) images by assigning a different primary color to each type of image. The resulting
fused images display multiple tissue characteristics that can be viewed simultaneously. Preliminary results indicate that
it may be possible to characterize breast masses on the basis of viewing the superimposed information. Such a
methodology has the potential to dramatically reduce the time required to view all the acquired data and to make a
clinical assessment. Since the color scale can be quantified, it may also be possible to segment such images in order to
isolate the regions of interest and to ultimately allow automated methods for mass detection and characterization.
A simple, room temperature, one-pot method to produce biocompatible CdSe/CdS quantum dots (QDs) in aqueous solution is presented. CdCl2 and NaSeSO3 are the precursors for the CdSe core where gelatin is used as an inhibitor. A CdS shell is grown by injecting H2S gas, generated by a reaction between sulfuric and sodium sulfide, into the solution. This fast, low cost synthesis approach is simple for scale-up production of QDs. Transmission electron microscopy shows that the bare CdSe quantum dots were 2-3 nm in diameter. The emission peak from the CdSe can be tuned over most of the visible wavelength (from 520nm to 600 nm) as the diameter of the QDs is allowed to increase before growth of the CdS shell. The core/shell structure was confirmed via UV-Vis absorption spectroscopy, PL studies, and structural characterization (XRD). The higher band gap CdS coatings significantly enhanced the photoluminescence (PL) of CdSe quantum dots by a factor of 2-3. However, the large lattice mismatch between the CdS coating and the CdSe core results in eventually quenched luminescence from CdSe with thicker CdS coatings. To increase the photochemical stability and biocompatibility of the CdSe/CdS QDs, a silica coating is grown directly on the QDs. Preliminary data indicates that the PL from CdSe/CdS QDs post-growth is affected as the applied electric field is altered. Efforts to functionalize the QDs with DNA and antibodies have begun. Studies have been initiated to demonstrate the feasibility of microinjecting the QDs into Xenopus embryo with minimal post-synthesis processing.
Gram-negative bacteria initiate a stress response in which the cells efflux potassium when electrophilic toxins are introduced into their environment. Hence, measurement of K+ concentration in the surrounding water using a fluorescence-based potassium-selective optode has been proposed for environmental and homeland security applications. Unfortunately, the fluorophore commonly used in such an optode is inefficient. Surface enhanced fluorescence (SEF) can be used to increase its fluorescence efficiency, which will improve the sensor's performance. To understand this phenomenon before applying it to the optode system, Rose Bengal (RB), an inexpensive and well characterized dye, in solution with gold and silver nanoparticles was studied. As expected, fluorescence from RB-gold solutions was low since alignment of gold's surface plasmon resonance (SPR) peak and absorption and fluorescence energies in RB favored energy transfer from RB to the gold nanoparticles. The alignment of the silver's SPR peak and the RB transitions favored transfer from silver to RB. SEF was observed in solutions with large dye-to-silver separation. However, little fluorescence was observed when the solution was pumped at the silver's SPR peak. Fluorescence from the dye decreased as dye-to-silver separation decreased. An explanation for these observations is presented; additional research is needed to develop a complete understanding.