Preliminary Imaging Research Articles

Abstract WMP71: Multimodal Imaging Yields Low Number of Stroke Mimics Treated With Thrombolytic Therapy Without Sacrificing Door-to-Needle Times

Introduction: Speed is critical in fibrinolytic therapy for acute ischemic stroke (AIS), but rapid decision-making may increase tPA use in stroke mimics. Complications from lytics in mimic patients, though uncommon, can be severe. Mimic treatment rates when using non-contrast CT as the only initial imaging modality have increased to as high as 34% with intensified efforts to reduce door to needle (DTN) times. Efficient imaging with MRI or multimodal CT may potentially avoid high mimic treatment rates without prolonging treatment. Methods: In a prospectively maintained registry, we examined all patients treated with IV tPA from January 2010 to June 2015. Institutional policy was to perform MRI first in AIS patients and start tPA on the MR table after DWI showed ischemia and GRE excluded hemorrhage; if MRI could not be performed, multimodal CT with CTA and CTP was performed. Results: Among 319 IV tPA treated patients, age was 71 (±15), 50% were female, and NIHSS was 13.3 (±8.0). Imaging modality before tPA was MR in 193 (61%) and CT in 126 (39%). In the entire population, the DTN time was 54 (IRQ 42-73) mins and the proportion of mimic patients was 3.1%. DTN times decreased steadily throughout the 5.5 year study period, and did not differ among patients imaged with MR vs CT (Figure). The reduction in DTN times was not associated with an increase in mimic-treated rates (Figure). Among the mimic patients, final diagnoses were migraine - 4, seizure - 3, meningitis - 1, PE - 1, and cardiac dysrhythmia - 1. Imaging modalities in mimic patients were MRI in 5 and CT in 5. Preliminary imaging reads suggested abnormality in 2/10, but final reads were normal in all. In 3/10 mimic patients, tPA infusions were stopped before full dose when ongoing imaging further clarified diagnosis. Conclusion: A rapid stroke assessment protocol using MRI or multimodal CT permits swift start of thrombolytic therapy and low rates of stroke mimic treatment. Figure. Door-to-needle time and percent stroke mimics by year.

Abstract TP391: Working Within a Stroke System of Care to Decrease Door to Transfer Times From Spoke to Hub

Background: Best practice recommends that hospitals treating acute stroke patients have protocols in place to ensure rapid transfer to an advanced facility for a higher level of care, if needed. Our system of hospitals consists of five primary stroke centers (PSC) and one comprehensive stroke center (CSC) in a major metropolitan area. PSCs utilize telemedicine for acute stroke decision-making and patients are transferred to the CSC for consideration of advanced treatments when deemed appropriate by the care team. Purpose: Our study objective was to streamline processes at our PSCs to decrease the door to transport time (DTT) to the CSC. Methods: Stroke coordinators from the six sister hospitals meet quarterly to collaborate and share best practices in patient care. Our team of nurse leaders determined potential strategies to eliminate wasted time in the transfer process. Team members went back to their home facilities with the goal of generating buy-in from individual caregivers to decrease the time to transport out to the CSC. An overall attitude of urgency was encouraged during meetings with stroke councils and providers. Preliminary imaging results were used to guide decision to transfer, rather than waiting for final results. Some hospitals chose to notify the flight team of potential transport earlier in the emergency department stay, while others are still in the process of affecting change. We collected data on transferred patients with a diagnosis of acute stroke between the dates of 2/1/15-7/31/15 (n=23) and compared against the same time period in 2014 (n=11). Results: A total of 34 patients were included in our retrospective chart review. The number of patients transferred for consideration of additional acute treatment increased from 11 in 2014 to 23 during the study period in 2015. When examining patients who transferred and actually received endovascular treatment for acute stroke (n=8 in 2014 versus n=11 in 2015), the mean DTT decreased from 84 minutes in 2014, to 77 minutes in 2015. We also noted that patient transfers were faster during day time hours when compared to night. Conclusions: A system-wide, collaborative approach between PSCs and CSCs can decrease DTT when nurse leaders and providers streamline processes.

Optimizing modality selection for image-guided procedures: an analysis of the challenges to ultrasound guidance.

Selection of the most appropriate modality for image guidance is essential for procedural success. We identified specific factors contributing to failure of ultrasound-guided procedures that were subsequently performed using CT guidance. This single-center, retrospective study included 164 patients who underwent a CT-guided biopsy, aspiration/drainage, or ablation after initially having the same procedure attempted unsuccessfully with ultrasound guidance. Review of the procedure images, reports, biopsy results, and clinical follow-up was performed and the reasons for inability to perform the procedure with ultrasound guidance were recorded. Patient cross-sectional area and depth to target were calculated. Differences in area and depth were compared using general linear modeling. Depth as a predictor of an unfavorable body habitus designation was modeled using logistic regression. US guidance was successful in the vast majority of cases (97%). Of the 164 procedures, there were 92 (56%) biopsies, 63 (38%) aspirations/drainages, and 9 (5%) ablations. The most common reason for procedure failure was poor acoustic window (83/164, 51%). Other reasons included target lesion being poorly discerned from adjacent tissue (61/164, 37%), adjacent bowel gas (34/164, 21%), body habitus (27/164, 16%), and gas-containing collection (22/164, 13%). Within the biopsy subgroup, patients for whom body habitus was a limiting factor were found to have on average a larger cross-sectional area and lesion depth relative to patients whose body habitus was not a complicating factor (p<0.0001 and p=0.0009). Poor acoustic window was the most common reason for procedural failure with ultrasound guidance. In addition, as lesion depth increased, the odds that body habitus would limit the procedure also increased. If preliminary imaging suggests a limited sonographic window, particularly for deeper lesions, proceeding directly to CT guidance should be considered.

Molecular Probes for Imaging the Sigma-2 Receptor: In Vitro and In Vivo Imaging Studies.

The sigma-2 (σ2) receptor has been validated as a biomarker of the proliferative status of solid tumors. Therefore, radiotracers having a high affinity and high selectivity for σ2 receptors have the potential to assess the proliferative status of human tumors using noninvasive imaging techniques such as Positron Emission Tomography (PET). Since the σ2 receptor has not been cloned, the current knowledge of this receptor has relied on receptor binding studies with the radiolabeled probes and investigation of the effects of the σ2 receptor ligands on tumor cells. The development of the σ2 selective fluorescent probes has proven to be useful for studying subcellular localization and biological functions of the σ2 receptor, for revealing pharmacological properties of the σ2 receptor ligands, and for imaging cell proliferation. Preliminary clinical imaging studies with [18F]ISO-1, a σ2 receptor probe, have shown promising results in cancer patients. However, the full utility of imaging the σ2 receptor status of solid tumors in the diagnosis and prediction of cancer therapeutic response will rely on elucidation of the functional role of this protein in normal and tumor cell biology.

System of label-free three-dimensional optical coherence tomography angiography with high sensitivity and motion contrast and its applications in brain science

Combining three-dimensional (3D) imaging ability of optical coherence tomography (OCT) with movement recognition ability of dynamic scattering technique, label-free 3D OCT angiography can be realized, which has a wide range of applications in basic science research and clinical diagnosis. At no expense of line scanning speed, the scale of capillaries can be detected by improving the sensitivity through the interframe analysis. However, there exists a certain residual overlap between dynamic flow signals and static tissue beds due to a series of reasons, thus making it difficult to completely distinguish dynamic flow signals from static tissue beds. Thus, when it comes to threshold segmentation for the blood flow signal extraction, classification error rate is inevitable, resulting in the decrease of the motion contrast of angiogram. In order to reduce classification error rate between static tissue beds and dynamic flow signals for high motion-contrast angiography, we propose a method of component compounding in wavelet domain. Three main steps are needed for this method. Firstly, on the basis of two-dimensional (2D) discrete static wavelet transform, a frame image can be decomposed into multiple levels. Each level has four components, i.e., approximation component, horizontal detail component, vertical detail component and diagonal detail component. Different decomposition levels and types of wavelet can be selected according to the demand. Secondly, the algorithm of inverse iteration compounding is used, which contains the arithmetic mean and the geometric mean of the components of adjacent decomposition levels. The adopted order for inverse iteration compounding is from the last level to the first one. The weight of the arithmetic mean to the geometric mean is one to one. In this way, four compounding components can be obtained. Thirdly, a new frame image with higher motion contrast can be obtained by using 2D discrete static wavelet inverse transform of the four compounding components. Both flow phantom and live animal experiments are performed. The results show that classification error rate decreases by 83% and 71% respectively after component compounding in wavelet domain. Besides, the angiogram has an improved motion contrast and a better vessel connectivity, which may contribute to better and wider applications of OCT angiography. Furthermore, based on the developed system, the preliminary imaging studies on the model of local stroke are conducted. In this experiment, we record the 3D data of SD mouse brain before and after the local stroke and on the tenth day. As a consequence, a clear presentation for the whole process of stroke model formation, vessel damage and vessel recovery is achieved, which may be beneficial to studying the mechanism of local stroke model.

Synthesis and Preliminary PET Imaging Studies of a FAAH Radiotracer ([¹¹C]MPPO) Based on α-Ketoheterocyclic Scaffold.

Fatty acid amide hydrolase (FAAH) is one of the principle enzymes for metabolizing endogenous cannabinoid neurotransmitters such as anandamide, and thus regulates endocannabinoid (eCB) signaling. Selective pharmacological blockade of FAAH has emerged as a potential therapy to discern the endogenous functions of anandamide-mediated eCB pathways in anxiety, pain, and addiction. Quantification of FAAH in the living brain by positron emission tomography (PET) would help our understanding of the endocannabinoid system in these conditions. While most FAAH radiotracers operate by an irreversible ("suicide") binding mechanism, a FAAH tracer with reversibility would facilitate quantitative analysis. We have identified and radiolabeled a reversible FAAH inhibitor, 7-(2-[(11)C]methoxyphenyl)-1-(5-(pyridin-2-yl)oxazol-2-yl)heptan-1-one ([(11)C]MPPO) in 13% radiochemical yield (nondecay corrected) with >99% radiochemical purity and 2 Ci/μmol (74 GBq/μmol) specific activity. The tracer showed moderate brain uptake (0.8 SUV) with heterogeneous brain distribution. However, blocking studies with a potent FAAH inhibitor URB597 demonstrated a low to modest specificity to the target. Measurement of lipophilicity, metabolite, and efflux pathway analysis were also performed to study the pharmacokinetic profile of [(11)C]MPPO. In all, we reported an efficient radiolabeling and preliminary evaluation of the first-in-class FAAH inhibitor [(11)C]MPPO with α-ketoheterocyclic scaffold.

Flexible and Semitransparent Organolead Triiodide Perovskite Network Photodetector Arrays with High Stability.

Organolead triiodide perovskite (CH3NH3PbI3) as a light-sensitive material has attracted extensive attention in optoelectronics. The reported perovskite photodetectors (PDs) mainly focus on the individual, which limits their spatial imaging applications. Uniform perovskite networks combining transparency and device performance were synthesized on poly(ethylene terephthalate) (PET) by controlling perovskite crystallization. Photodetector arrays based on above network were fabricated to demonstrate the potential for image mapping. The trade-off between the PD performance and transparency was systematically investigated and the optimal device was obtained from 30 wt % precursor concentration. The switching ratio, normalized detectivity, and equivalent dark current derived shot noise as the critical parameters of PD arrays reached 300, 1.02 × 10(12) Jones, and 4.73 × 10(-15)A Hz(-1/2), respectively. Furthermore, the PD arrays could clearly detect spatial light intensity distribution, thus demonstrating its preliminary imaging function. The perovskite network PD arrays fabricated on PET substrates could also conduct superior flexibility under wide angle and large number of bending. For the common problem of perovskite optoelectronics in stability, the perovskite networks sheathed with hydrophobic polymers greatly enhanced the device stability due to the improved interface contacts, surface passivation, and moisture isolation. Taking into consideration transparency, flexibility, imaging and stability, the present PD arrays were expected to be widely applied in visualized portable optoelectronic system.

Morphological Abnormalities of Thalamic Subnuclei in Migraine: A Multicenter MRI Study at 3 Tesla.

This multicenter imaging study shows morphological thalamic abnormalities in a large cohort of patients with episodic migraine compared with healthy subjects using state-of-the-art MRI and advanced, fully automated multiatlas segmentation techniques. The results stress that migraine is a disorder of the CNS in which not only is brain function abnormal, but also brain structure is undergoing significant remodeling.

Longitudinal assessment of fractional anisotropy alterations caused by simian immunodeficiency virus infection: a preliminary diffusion tensor imaging study.

Previous diffusion tensor imaging (DTI) studies found that human immunodeficiency virus (HIV) infection led to white matter (WM) microstructure degeneration. Most of the DTI studies were cross-sectional and thus merely investigated only one specific point in the disease. In order to systematically study the WM impairments caused by HIV infection, more longitudinal studies are needed. However, longitudinal studies on HIV patients are very difficult to conduct. To address this question, we employed the simian immunodeficiency virus (SIV)-infected rhesus monkeys model to carry out a longitudinal DTI study. We aimed to longitudinally access the WM abnormalities of SIV-infected rhesus monkeys by studying the fractional anisotropy (FA) alterations with Tract Based Spatial Statistic (TBSS) analysis. Four rhesus monkeys inoculated intravenously with SIVmac239 were utilized in the study. DTI scans and peripheral blood CD4(+) and CD8(+) T cell counts were acquired prior to virus inoculation (as the baseline) and in the 12th and 24th week postvirus inoculation. Significant FA alterations were found in the two areas of the inferotemporal regions (iTE), respectively located in the ventral subregion of posterior iTE (iTEpv) and the dorsal subregion of iTE (iTEpd). The decreased FA values in iTEpd were found significantly negatively correlated with the elevated peripheral blood CD4(+)/CD8(+) ratios. It might suggest that WM in iTEpd was still impaired even though the immune dysfunction alleviated temporally.

A High-Resolution Time-of-Flight Clinical PET Detection System Using a Gapless PMT-Quadrant-Sharing Method

We developed a high-resolution Photomultiplier-Quadrant-Sharing (PQS) PET system for human imaging. This system is made up of 24 detector panels. Each panel (bank) consists of $3 \times 7$ detector blocks, and each block has $16 \times 16$ LYSO crystals of $2.35 \times 2.35 \times 15.2~\hbox{mm}^{3}$ . We used a novel detector-grinding scheme that is compatible with the PQS detector-pixel-decoding requirements to make a gapless cylindrical detector ring for maximizing detection efficiency while delivering an ultrahigh spatial-resolution for a whole-body PET camera with a ring diameter of 87 cm and axial field of view of 27.6 cm. This grinding scheme enables two adjacent gapless panels to share one row of the PMTs to extend the PQS configuration beyond one panel and thus maximize the economic benefit (in PMT usage) of the PQS design. The entire detector ring has 129,024 crystals, all of which are clearly decoded using only 576 PMTs (38-mm diameter). Thus, each PMT on average decodes 224 crystals to achieve a high crystal-pitch resolution of $2.44~\hbox{mm} \times 2.44~\hbox{mm}$ . The detector blocks were mass-produced with our slab-sandwich-slice technique using a set of optimized mirror-film patterns (between crystals) to maximize light output and achieve high spatial and timing resolution. This detection system with time-of-flight capability was placed in a human PET/CT gantry. The reconstructed image resolution of the system was about 2.87 mm using 2D-filtered back-projection. The time-of-flight resolution was 473 ps. The preliminary images of phantoms and clinical studies presented in this work demonstrate the capability of this new PET/CT system to produce high-quality images.

KEY SCIENCE OBSERVATIONS OF AGNs WITH THE KaVA ARRAY

KaVA (KVN and VERA Array) is a new combined VLBI array composed of KVN (Korean VLBI Network) and VERA (VLBI Exploration of Radio Astrometry). Here, we report the following two issues. (1) We review the initial results of imaging observations of M87 at 23 GHz following Niinuma et al. (2014). The KaVA images reveal extended outflows including complex substructures such as knots and limb-brightening, in agreement with previous VLBI observations. KaVA achieves a high dynamic range of ~ 1000, more than three times better than that achieved by VERA alone. (2) Based on subsequent observations and discussions led by the KaVA AGN SubWorking Group, we set monitoring observations of Sgr A * and M87 as our Key Science Project (hereafter KSP) because of the closeness and largeness of their central super-massive black holes. The main science goals of the KSP are (i) testing the magnetically-driven-jet paradigm by mapping velocity elds of the M87 jet, and (ii) obtaining tight constraints on physical properties of the radio emitting region in Sgr A * . Towards KSP, we show the first preliminary images of M87 at 23 GHz and Sgr A * at 43 GHz with the bandwidth of 256 MHz.

Snapshot retinal imaging Mueller matrix polarimeter.

Early diagnosis of glaucoma, which is a leading cause for visual impairment, is critical for successful treatment. It has been shown that Imaging polarimetry has advantages in early detection of structural changes in the retina. Here, we theoretically and experimentally present a snapshot Mueller Matrix Polarimeter fundus camera, which has the potential to record the polarization-altering characteristics of retina with a single snapshot. It is made by incorporating polarization gratings into a fundus camera design. Complete Mueller Matrix data sets can be obtained by analyzing the polarization fringes projected onto the image plane. In this paper, we describe the experimental implementation of the snapshot retinal imaging Mueller matrix polarimeter (SRIMMP), highlight issues related to calibration, and provide preliminary images acquired from the camera.

A flavone-based turn-on fluorescent probe for intracellular cysteine/homocysteine sensing with high selectivity

A new type of flavone-based fluorescent probe (DMAF) capable of cysteine (Cys)/homocysteine (Hcy) sensing with high selectivity over other amino acids was developed. Such type of probe undergoes Cys/Hcy-mediated cyclization reaction with the involvement of its aldehyde group, which suppresses of the photoinduced electron transfer (PET) process of the probe molecule and consequently leads to the enhancement of fluorescence emission upon excitation using visible light. The formation of product of the Cys/Hcy-mediated cyclization reaction was confirmed and the preliminary fluorescence imaging experiments revealed the biocompatibility of the as-prepared probe and validated its practicability for intracellular Cys/Hcy sensing.

Abstract 1492: Trastuzumab-induced normalization in a HER2+ murine model of breast cancer

Abstract Introduction: The primary goal of this study is to quantitatively map the vascular and cellular response to trastuzumab treatment in a murine model of HER2+ breast cancer. We report longitudinal dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) and immunohistochemical studies hypothesized to identify timing windows of trastuzumab-induced vascular normalization. Experimental Design: Mice were subcutaneously implanted with BT474 breast cancer cells and randomly assigned to treated (10 mg/kg trastuzumab) and control (saline) groups. After tumors reached ∼225 mm3, animals (n = 20) were imaged (7.0 T MRI) before treatment (day 0), and 24 hours after each treatment (day 1 and day 4). Subgroups were sacrificed for histology between days 0 through 10 (n = 45). DCE-MRI analysis yielded parametric maps of blood vessel perfusion and permeability (Ktrans) and the extravascular extracellular volume fraction (ve). Tumor sections were paraffin-embedded and stained with CD31, α-SMA, Ki67 and H&amp;E. Slides were scanned in high resolution (20×) and quantitatively analyzed with Leica SCN400 software. Results: Compared to controls, treated tumors exhibited a significant increase in Ktrans (p = 0.03) on day 4, indicative of enhanced vessel perfusion and/or permeability. Additionally at day 4, treated tumors exhibited a significant increase in extravascular extracellular volume fraction measured via ve (p = 0.01), indicating increased cell death. These significant changes occurred prior to a significant change in tumor size at day 4 (p = 0.11). Decreased Ki67 proliferation staining (p = 0.02) at day 3 and a significant decrease in tumor volume at day 7 (p = 0.04) in the treated group confirmed tumor response to trastuzumab. The increase in Ktrans suggests properties of vessel normalization with potential to improve delivery of systemic therapies. Immunohistochemical analyses showed treated tumors have a significant decrease in microvessel density (CD31 staining, p &amp;lt; 0.01), with a simultaneous significant increase in α-SMA staining (pericyte coverage, p = 0.05) on day 4; thus, there was an overall increase in the “vessel maturation index” (ratio of α-SMA to CD31 staining) compared to controls (p = 0.01). Conclusion: These concordant (though preliminary) imaging and histological data suggest that trastuzumab treatment promotes vascular normalization, providing motivation for future studies designed to improve the efficacy of combination therapies in HER2+ breast cancer. For example, DCE-MRI has the potential to identify windows of vascular normalization thereby indicating optimal timing for treatment dosing with a cytotoxic therapy. As trastuzumab is currently given clinically in combination with various chemotherapies for HER2+ cancer, trastuzumab-induced vascular normalization could be utilized to improve drug delivery efficiency and enhance overall patient response without increasing dose or systemic toxicity. Citation Format: Anna G. Sorace, Jennifer G. Whisenant, J. Oliver McIntyre, Thomas E. Yankeelov. Trastuzumab-induced normalization in a HER2+ murine model of breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1492. doi:10.1158/1538-7445.AM2015-1492

Iterative reconstruction for pet scanners with continuous scintillators.

Several technical developments have led to a comeback of the continuous scintillators in positron emission tomography (PET). Important differences exist between the resurgent continuous scintillators and the prevailing pixelated devices, which can translate into certain advantages of the former over the latter. However, if the peculiarities of the continuous scintillators are not considered in the iterative reconstruction in which the measured data is converted to images, these advantages will not be fully exploited. In this paper, we review which those peculiarities are and how they have been considered in the literature of PET reconstruction. In light of this review, we propose a new method to compute one of the key elements of the iterative schemes, the system matrix. Specifically, we substitute the traditional Gaussian approach to the so-called uncertainty term by a more general Monte Carlo estimation, and account for the effect of the optical photons, which cannot be neglected in continuous-scintillators devices. Finally, we gather in a single scheme all the elements of the iterative reconstruction that have been individually reformulated, in this or previous works, for continuous scintillators, providing the first reconstruction framework fully adapted to this type of detectors. The preliminary images obtained for a commercially available PET scanner show the benefits of adjusting the reconstruction to the nature of the scintillators.

Synthesis and in Vivo Evaluation of [123I]Melanin-Targeted Agents.

This study reports the synthesis, [(123)I]radiolabeling, and biological profile of a new series of iodinated compounds for potential translation to the corresponding [(131)I]radiolabeled compounds for radionuclide therapy of melanoma. Radiolabeling was achieved via standard electrophilic iododestannylation in 60-90% radiochemical yield. Preliminary SPECT imaging demonstrated high and distinct tumor uptake of all compounds, as well as high tumor-to-background ratios compared to the literature compound [(123)I]4 (ICF01012). The most favorable compounds ([(123)I]20, [(123)I]23, [(123)I]41, and [(123)I]53) were selected for further biological investigation. Biodistribution studies indicated that all four compounds bound to melanin containing tissue with low in vivo deiodination; [(123)I]20 and [(123)I]53 in particular displayed high and prolonged tumor uptake (13% ID/g at 48 h). [(123)I]53 had the most favorable overall profile of the cumulative uptake over time of radiosensitive organs. Metabolite analysis of the four radiotracers found [(123)I]41 and [(123)I]53 to be the most favorable, displaying high and prolonged amounts of intact tracer in melanin containing tissues, suggesting melanin specific binding. Results herein suggest that compound [(123)I]53 displays favorable in vivo pharmacokinetics and stability and hence is an ideal candidate to proceed with further preclinical [(131)I] therapeutic evaluation.

Utility of Computed Tomography following Anterior Cervical Diskectomy and Fusion.

Study Design Retrospective case series. Objective To assess the utility of postoperative computed tomography (CT) following anterior cervical diskectomy and fusion (ACDF) and to determine the clinical circumstances most likely to lead to an abnormal CT scan. Methods Patients who underwent ACDF at a tertiary center over a span of 5 years were investigated. Only patients who had a minimum of 6 months' postoperative follow-up and a CT within 2 years after the surgery were included in the study group. All the postoperative notes were reviewed to determine indications for the CT, abnormalities identified, and whether the scan led to an alteration in the treatment course. Results The charts of 690 patients who underwent ACDF were reviewed. Of the 690 patients, 45 (7%) had postoperative CTs. These patients accounted for 53 postoperative CT scans, 45 (85%) of which were taken for patients who expressed persistent postoperative symptoms and/or had abnormal imaging. There were no indications for 8 (15%) of the CTs. Patients who had a CT for persistent symptoms and/or abnormal preliminary imaging were significantly more likely to have an abnormal CT (p = 0.03) and/or an alteration in treatment course (p = 0.04) compared with those with no symptomatic or radiologic indication for CT. Conclusions CT is associated with minimal utility regarding the alteration of treatment course when employed in asymptomatic patients. Postoperative CT should be ordered solely for symptomatic patients or those with other abnormal preliminary imaging. Judicious use of postoperative CT will limit the radiation exposure and cost.

Development of (153) Sm-folate-polyethyleneimine-conjugated chitosan nanoparticles for targeted therapy.

The aim of this study was to develop biocompatible, water-soluble (153) Sm-labeled chitosan nanoparticles (NPs) containing folate and polyethyleneimine functionalities i.e. chitosan-graft-PEI-folate (CHI-DTPA-g-PEI-FA), suitable for targeted therapy. The physicochemical properties of the obtained NPs were characterized by dynamic light-scattering analysis for their mean size, size distribution, and zeta potential; scanning electron microscopy for surface morphology; and (1) H-NMR, FT-IR analyses for molecular dispersity of folate in the NPs. NPs were spherical with mean diameter below 250 nm, polydispersity of below 0.15, and positive zeta potential values. The NP complex ((153) Sm-CHI-DTPA-g-PEI-FA) was stable at 25 °C (6-8 h, >90% radiochemical purity, instant thin layer chromatography (ITLC)). Binding studies using fluorescent NPs for internalization also demonstrated significant uptake in MCF-7 cells. MCF-7 cell internalization was significantly greater for 4T1. In blocking studies, both MCF-7 and 4T1 cell lines demonstrated specific folate receptor (FR) binding (decreasing 45%). In vivo biodistribution studies indicated major excretion of NPs metabolites and/or free (153) Sm through the kidneys. The preliminary imaging studies in 4T1 tumor-bearing mice showed minor uptake up to 96 h. The present folic acid that functionalized chitosan NP is a candidate material for folate receptor therapy.

WE‐EF‐210‐07: Development of a Minimally Invasive Photo Acoustic Imaging System for Early Prostate Cancer Detection

Purpose:The objective of this work is to design, implement and characterize a catheter‐based ultrasound/photoacoustic imaging probe for early‐diagnosis of prostate cancer and to aid in image‐guided radiation therapy.Methods:The need to image across 6–10cm of tissue to image the whole prostate gland limits the resolution achievable with a transrectal ultrasound approach. In contrast, the urethra bisects the prostate gland, providing a minimally invasive pathway for deploying a high resolution ultrasound transducer. Utilizing a high‐frequency (20MHz) ultrasound/photoacoustic probe, high‐resolution structural and molecular imaging of the prostate tissue is possible. A custom 3D printed probe containing a high‐frequency single‐element ultrasound transducer is utilized. The diameter of the probe is designed to fit inside a Foley catheter and the probe is rotated around the central axis to achieve a circular B‐scan. A custom ultrasound amplifier and receiver was set up to trigger the ultrasound pulse transmission and record the reflected signal. The reconstructed images were compared to images generated by traditional 5 MHz ultrasound transducers.Results:The preliminary results using the high‐frequency ultrasound probe show that it is possible to resolve finely detailed information in a prostate tissue phantom that was not achievable with previous low‐frequency ultrasound systems. Preliminary ultrasound imaging was performed on tissue mimicking phantom and sensitivity and signal‐to‐noise ratio of the catheter was measured.Conclusion:In order to achieve non‐invasive, high‐resolution, structural and molecular imaging for early‐diagnosis and image‐guided radiation therapy of the prostate tissue, a transurethral catheter was designed. Structural/molecular imaging using ultrasound/photoacoustic of the prostate tissue will allow for localization of hyper vascularized areas for early‐stage prostate cancer diagnosis.

SU‐E‐E‐06: Teaching About the Gamma Camera and Ultrasound Imaging

Purpose:Instructional modules on applications of physics in medicine are being developed. The target audience consists of students who have had an introductory undergraduate physics course. This presentation will concentrate on an active learning approach to teach the principles of the gamma camera. There will also be a description of an apparatus to teach ultrasound imaging.Methods:Since a real gamma camera is not feasible in the undergraduate classroom, we have developed two types of optical apparatus that teach the main principles. To understand the collimator, LEDS mimic gamma emitters in the body, and the photons pass through an array of tubes. The distance, spacing, diameter, and length of the tubes can be varied to understand the effect upon the resolution of the image. To determine the positions of the gamma emitters, a second apparatus uses a movable green laser, fluorescent plastic in lieu of the scintillation crystal, acrylic rods that mimic the PMTs, and a photodetector to measure the intensity. The position of the laser is calculated with a centroid algorithm.To teach the principles of ultrasound imaging, we are using the sound head and pulser box of an educational product, variable gain amplifier, rotation table, digital oscilloscope, Matlab software, and phantoms.Results:Gamma camera curriculum materials have been implemented in the classroom at Loyola in 2014 and 2015. Written work shows good knowledge retention and a more complete understanding of the material. Preliminary ultrasound imaging materials were run in 2015.Conclusion:Active learning methods add another dimension to descriptions in textbooks and are effective in keeping the students engaged during class time. The teaching apparatus for the gamma camera and ultrasound imaging can be expanded to include more cases, and could potentially improve students’ understanding of artifacts and distortions in the images.