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All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Florida International University Research on Soil and Groundwater Contamination at DOE's Hanford and Savannah River Sites - 18547

Nuclear weapons production and other defense-related activities at U.S. Department of Energy (DOE) sites have resulted in radionuclide and heavy metal contamination in surface and subsurface environments nationwide. The DOE Office of Environmental Management (DOE EM) faces a number of environmental challenges that are technically complex and unique to EM with tremendous associated cleanup costs. The success of the DOE EM mission will require development and insertion of innovative approaches and novel technologies to address the significant challenges associated with the remaining cleanup of contaminated sites. A key focus of the applied research portfolio addresses data gaps related to the behavior and chemistry of radionuclides of concern as well as the co-mingling of these contaminants in groundwater at EM sites such as Hanford, Savannah River, Oak Ridge and others. Florida International University (FIU) is conducting research in conjunction with Pacific Northwest National Laboratory (PNNL) and savannah River National Laboratory (SRNL) scientists to support environmental remediation efforts at Hanford and SRS. This research is focused on remediation technologies for contaminated soil and groundwater as well as the assessment of the fate and transport of contaminants in the environment. The overall objective is to reduce contaminant mobility through the development and application of state-of-the-art scientific and environmental remediation technologies. The FIU strategy is to conduct basic science research that fills knowledge gaps and complements work conducted at DOE sites. Support to Hanford includes contributing to the understanding of {sup 99}Tc chemistry and the fate and transport mechanisms of co-mingled contaminants including {sup 99}Tc, U(VI), Cr, and iodine (I). FIU has also provided basic science research that supports a treatability study currently underway at Hanford, which uses ammonia gas injection to manipulate pH and immobilize U(VI) in the subsurface. In addition, support for long-term monitored natural attenuation is provided through geophysical research that monitors subsurface contaminant and microbial responses. Research to evaluate the environmental factors that control the fate and transport of contaminants and co-contaminants in soil and groundwater is being performed for SRS. This research has contributed to the development, design, and deployment of innovative strategies to enhance the natural attenuation processes and to validate novel in situ remediation technologies. The SRS EM test bed demonstrations directly benefit SRS cleanup initiatives. Current investigations focus on natural organic compounds, such as humate, as a potential amendment for the treatment of uranium in groundwater associated with the SRS F-Area Seepage Basins plume, investigates the synergy between humate and silica to optimize the pH adjustment strategy for uranium remediation and investigates the interaction of Tc and I with soil from the Four Mile Branch wetland. Collaborative relationships between FIU and the national laboratories have provided synergy and benefits over the years to FIU, the national laboratories, the DOE complex, and the DOE EM mission. By working closely with the national laboratories, FIU research is not only closely aligned with the cleanup mission priorities at the DOE sites, but complements and supports the work at national laboratories. This coordination and leveraging of research efforts results in time- and cost-savings, and accelerates progress in the DOE EM environmental restoration mission. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Experimental study of {sup 99m}Tc-aluminum oxide use for sentinel lymph nodes detection

The purpose of the study was a comparative research in the possibility of using the radiopharmaceuticals {sup 99m}Tc-Al{sub 2}O{sub 3} and {sup 99m}Tc-Nanocis for visualizing sentinel lymph nodes. The measurement of the sizes of {sup 99m}Tc-Al{sub 2}O{sub 3} and {sup 99m}Tc-Nanocis colloidal particles was performed in seven series of radiopharmaceuticals. The pharmacokinetics of {sup 99m}Tc-Al{sub 2}O{sub 3} and {sup 99m}Tc-Nanocis was researched on 50 white male rats. The possibility of the use of {sup 99m}Tc-Al{sub 2}O{sub 3} and {sup 99m}Tc-Nanocis for lymphoscintigraphy was studied in the experiments on 12 white male rats. The average dynamic diameter of the sol particle was 52–77 nm for {sup 99m}Tc-Al{sub 2}O{sub 3} and 16.7–24.5 nm for {sup 99m}Tc-Nanocis. Radiopharmaceuticals accumulated in the inguinal lymph node in 1 hour after administration; the average uptake of {sup 99}mTc-Al{sub 2}O{sub 3} was 8.6% in it, and the accumulation of {sup 99m}Tc-Nanocis was significantly lower—1.8% (p < 0.05). In all study points the average uptake of {sup 99m}Tc-Al{sub 2}O{sub 3} in the lymph node was significantly higher than {sup 99m}Tc-Nanocis accumulation. The results of dynamic scintigraphic studies in rats showed that {sup 99m}Tc-Al{sub 2}O{sub 3} and {sup 99m}Tc-Nanocis actively accumulated into the lymphatic system. By using {sup 99m}Tc-Al{sub 2}O{sub 3} inguinal lymph node was determined in 5 minutes after injection and clearly visualized in all the animals in the 15th minute, when the accumulation became more than 1% of the administered dose. Further observation indicated that the {sup 99m}Tc-Al{sub 2}O{sub 3} accumulation reached a plateau in a lymph node (average 10.5%) during 2-hour study and then its accumulation remained practically at the same level, slightly increasing to 12% in 24 hours. In case of {sup 99m}Tc-Nanocis inguinal lymph node was visualized in all animals for 15 min when it was accumulated on the average 1.03% of the administered dose. Plateau of {sup 99m}Tc-Nanocis accumulation in the lymph node (average 2.05%) occurred after 2 hours of the study and remained almost on the same level (in average 2.3%) for 24 hours. Thus, the experimental study of a new domestic radiopharmaceutical showed that the {sup 99m}Tc-Al{sub 2}O{sub 3} accumulates actively in the lymph nodes several times as compared to the imported analogue and its practical application will facilitate intraoperative identification of sentinel lymph nodes.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Preparation, Performance and Mechanism of Tc and I Getters in Cementitious Waste Forms - 17124

Cementitious waste forms offer a low temperature, cost effective technology for the solidification of liquid wastes. At the Department of Energy Hanford Site, 99-Tc and 129-I are radionuclides contained within low activity waste (LAW) which contribute significantly to environmental impacts associated with clean-up of the site. Cast Stone, a cementitious waste form comprised of 47 wt% blast furnace slag, 45 wt% fly ash and 8 wt% ordinary Portland cement, has undergone investigation as a possible candidate technology for the solidification of LAW. In screening tests using EPA Method 1315 leach testing of various mixes of Cast Stone with simulated LAW, Tc observed effective diffusivities (Dobs) had an average of 5.3 x 10-11 cm{sup 2}/s and I Dobs had an average of 5.7 x 10-9 cm{sup 2}/s. From these measurements, an opportunity exists to improve retention of Tc and I by Cast Stone. One approach to accomplish this is through the incorporation of Tc and I getters to selectively sequester Tc and I in the waste stream and eventual waste form. Initial testing conducted at PNNL identified potassium metal sulfide (KMS-2) and Sn(II)-apatite (Sn-A) as the strongest performing Tc getters and silver exchanged zeolite (Ag-Z) as the top performing I getter. This research also demonstrated that the Tc and I getters, when added to solution simultaneously, can have deleterious interactions with one another and lower the Tc and I removal levels. However, these interactions can be overcome through sequential treatment of solution with the getters. Cast Stone samples were fabricated using a 6.5 M Na average LAW simulant spiked with Tc and I with the addition of various combinations of Tc and I getters. Through EPA Method 1315 and Method 1313 testing it was found that the KMS-2 Tc getter was most successful at lowering Tc Dobs. The I getters were not effective, as apparent interference from sulfide components of the waste form may have led to dissociation of the AgI formed by the Ag-Z getter in sequestering the I from solution. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Effects of redox cycling of iron in nontronite on reduction of technetium

In situ technetium-99 ( 99 Tc) immobilization by Fe(II) associated with clay minerals is a potential cost-effective method for Tc remediation at contaminated sites. The oxidation state of Fe is constantly cycled in sedimentary environments, however the effect of this cycle on Tc reduction and immobilization has not yet been investigated. The objective of this project was therefore to study how multiple cycles of reduction-reoxidation of Fe-rich clay mineral, nontronite, affected its reactivity toward Tc (VII) reduction. Iron-rich nontronite NAu-2 was used as a model clay mineral. NAu-2 suspension was first bioreduced by Shewanella putrefaciens CN32, which was subsequently re-oxidized by air. Three cycles of reduction-oxidation were conducted and bioreduced NAu-2 samples from all three cycles were collected and used for Tc(VII) reduction experiments. Each redox cycle resulted in a small fraction of dissolution of small size and/or poorly crystalline NAu-2. The released Fe(II) from the dissolution was likely adsorbed onto NAu-2 surface/edge sites with a high reactivity. Upon exposure to O2, this reactive Fe(II) fraction was oxidized more rapidly than structural Fe(II) and may have accounted for a two-step reoxidation kinetics of NAu-2 associated Fe(II): rapid oxidation over first few hours followed by slow oxidation. Progressive increase of this reactive fraction of Fe(II), from increased dissolution, accounted for the successively higher rate of bioreduction and reoxidation with increased redox cycles. The same Fe redistribution accounted for two-step Tc(VII) reduction kinetics as well. Rapid Tc(VII) reduction in the first few hours may be attributed to a small fraction of highly reactive Fe(II) at the NAu-2 surface/edge sites, and more steady Tc(VII) reduction over longer time may be carried out by structural Fe(II). Similar to the increased rates of Fe(III) reduction and Fe(II) oxidation, the Tc(VII) reduction rate also increased with redox cycles and could be explained by progressive increase of the reactive Fe(II) on NAu-2 surface/edges. Iron-rich clay minerals undergo important changes after redox cycles, but eventually reach a steady state with continued reactivity toward heavy metals.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Simulating field conditions for the curing of salt-stone - 15501

salt-stone is a cementitious, low-level waste (LLW) material processed and stored at the Savannah River Site (SRS). It consists of fly ash (FA), blast furnace slag (BFS), and Portland cement that are blended with LLW salt solution. The dry feed materials and the salt solution are mixed at the salt-stone Production Facility (SPF), and the fresh grout subsequently pumped into a salt-stone Disposal Unit (SDU) in the salt-stone Disposal Facility (SDF) where it cures to form a rigid, cementitious monolith. In order to demonstrate the long-term performance of salt-stone, non-radioactive simulant samples are processed and cured in a laboratory environment and subsequently tested with respect to key performance properties. Of particular relevance to assessing the long-term stabilization and immobilization of radionuclides in salt-stone is the permeability, or saturated hydraulic conductivity, which determines the rate of infiltration for oxygen-bearing ground waters that can affect redox sensitive contaminants, such as {sup 99}Tc. Environmental conditions in the SDU, in particular temperature and humidity, are believed to affect the cured properties of salt-stone. With respect to humidity it has been determined that the average vapor space humidity in an SDU is at least 95%, and in addition the assumption can be made that underlying grout is subjected to a moisture-saturated environment by the grout poured over it. With respect to temperature, the SDUs contain thermo-well arrays that provide detailed vertical, and to a lesser degree radial, temperature profiles. Temperature data from the SDUs have subsequently been utilized to better simulate curing temperatures for simulant salt-stone in the laboratory. However, no two thermal profiles are the same, varying with respect to the following parameters: initial temperature, rate of temperature increase, maximum temperature attained, time at maximum temperature, and cooling rate. These temperature variables are dependent on the depth of grout (due to insulating effects of underlying and overlying grout), frequency of grout addition to the SDU (with more frequent additions causing grout temperatures to rise due to the exothermic hydration reactions), and, to a lesser degree, the ambient temperature of the external environment. Due to the variability in each thermal profile recorded in an SDU, the question arises as to which profile (or profiles) should be used in the simulated laboratory environment to best mimic the curing of field emplaced salt-stone, such that there is confidence that the properties measured for laboratory-prepared samples are representative of the grout in the SDU. Since the current SDU design contains sixty-six thermo-wells it is obviously not practical to process simulant samples according to each profile. Rather the aim would be to choose a reduced number of profiles that adequately encompass the range of recorded profiles, or to choose a single profile that is considered most conservative with respect to the resulting properties of interest. This is typically thought to be the profile exhibiting the highest peak temperature since for cement-based materials higher curing temperatures (> 60 deg. C), while resulting in enhanced reaction kinetics and strength development for short curing durations (∼28 days), have been shown to adversely affect the physical properties of the material after extended cure times. In choosing representative profiles it is important to consider not only the maximum temperature, but also the influence of rate of temperature rise to the maximum temperature, and time at or close to the maximum temperature on the post-cured properties. The intent of this paper is to consider the varied curing temperature profiles to which the salt-stone is exposed in an SDU, and to analyze the currently available data for elevated temperature curing of salt-stone to determine the potential thermal effects on the saturated hydraulic conductivity of salt-stone emplaced in an SDU. This may subsequently facilitate a more informed approach to simulating the curing of salt-stone in a laboratory environment. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Effectiveness of Repeat Angiographic Assessment in Patients Designated for Radioembolization Using Yttrium-90 Microspheres With Initial Extrahepatic Accumulation of Technitium-99m Macroaggregated Albumin: A Single Center's Experience

Purpose: To evaluate the efficacy of a workflow consisting of repeat assessment in patients planned for yttrium-90 ({sup 90}Y) radioembolization in case of nontarget visceral technetium-99m ({sup 99m}Tc)-macroaggregated albumin (MAA) accumulation despite initial prophylactic coil embolization of nonhepatic arteries. Materials and Methods: In 341 patients with primary and secondary liver cancer, pretreatment hepatic angiograms, as well as single-photon emission computed tomography coregistered with magnetic resonance imaging scans, were obtained. Extrahepatic tracer deposition was identified in 33 patients (9.7%) necessitating repeat assessment. Images were reviewed to correlate the site of MAA accumulation with causative gastrointestinal vessels, and repeat angiograms served as reference standard. Results: At repeat angiography, the source of extrahepatic flow was identified and eliminated in 31 of 33 patients (93.9%). In 20 patients (60.6%), successful embolization of nontarget vessels was achieved, in 13 patients (39.4%), MAA was administered more distally. Afterward, extrahepatic MAA deposition was eliminated in 30 patients (90.9%). Conclusion: The algorithm of repeat assessment in case of extrahepatic MAA accumulation has proven highly effective to eliminate extrahepatic shunting, thus decreasing the risk of postradioembolization complications due to inadvertent visceral microsphere deposition.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

The Caudate Lobe: The Blind Spot in Radioembolization or an Overlooked Opportunity?

PurposeThe caudate lobe (CL) is impartial to the functional left and right hemi-liver and has outspoken inter-individual differences in arterial vascularization. Unfortunately, this complexity is not specifically taken into account during radioembolization treatment (RE), potentially resulting in under- or overtreatment of the CL. The objective of this study was to evaluate the CL coverage in RE and determine the detection rate of the CL arteries on CT angiography during work-up.MethodsIn all consecutive patients who underwent RE treatment between May 2012–January 2015, {sup 99m}Tc-MAA SPECT/CT and posttreatment scans ({sup 90}Y-bremsstrahlung SPECT/CT, {sup 90}Y-PET/CT, or {sup 166}Ho-SPECT/CT) were reviewed for activity in the CL. Pretreatment CT angiographies were reviewed for the visibility of the CL arteries.ResultsEighty-two patients were treated. In 32/82 (39 %) the CL was involved. In 6/32 (19 %) patients, no activity was seen on the posttreatment scan in the CL, whereas in 40/50 (80 %) patients without CL tumor involvement, the CL was treated. {sup 99m}Tc-MAA SPECT/CT and final posttreatment scans were discordant in 16/78 (21 %). {sup 99m}Tc-MAA SPECT/CT had a positive and negative predictive value of 94 % and 46 %, respectively, for activity in the CL after RE. In untreated CLs, significant hypertrophy was observed with a median volume increase of 33 % (p = 0.02). CL arteries were seldom visible on the pretreatment CT; the identification rate was 12–17 %.ConclusionCurrently in RE treatments, targeting or sparing of the CL is highly erratic and independent of tumor involvement. Intentional treatment or bypassing of the CL seems worthwhile to either improve tumor coverage or enhance the functional liver remnant.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Angiographic Anatomy and Relevance of 3 and 9 O’clock Arteries During Radioembolization

Purpose3 and 9 o’clock arteries (3&9As) which supply the common hepatic duct connect hepatic with duodenal/pancreatic territories. The study purpose is to describe the angiographic anatomy of 3&9As and discuss their relevance when performing radioembolization (RE) of liver malignancies.Materials and MethodsThe anatomy of the 3&9As was systematically investigated by a retrospective analysis of angiograms, technetium Tc-99 m-macroaggregated albumin (MAA) scintigrams, yttrium-90 (Y90) Bremsstrahlung-SPECT/CT datasets, and clinical data of 153 patients who underwent RE between 2010 and 2013.ResultsAnalysis of preprocedural angiograms identified 3&9As in 36 (24%) of the 153 patients. Following embolization of the gastroduodenal artery, 3&9As were seen in 53 cases (35%). The three most common origins of the 3&9As were the right hepatic artery (n = 14), the cystic artery (n = 11), and S5 and S6 segmental arteries (n = 5 each). Extrahepatic Tc-99 m-MAA deposition in the territory of the 3&9As was significantly more frequent when 3&9As were detectable on preprocedural angiograms (28%{sub visible} vs. 11%{sub not} {sub visible}; p = 0.001) and especially when the 3&9As were not embolized or bridged prior to RE (50%{sub not} {sub occluded/bridged} vs. 19%{sub occupied/bridged}; p = 0.043). The presence of extrahepatic Y90 Bremsstrahlung after RE (n = 17) was attributable to microsphere diversion via the 3&9A territory in four patients and possible diversion via this territory in nine patients. Five of these 13 patients presented with epigastric pain, nausea, or vomiting (CTCAE severity grade ≤ 3) (p = 0.014).Conclusion3&9As are commonly detectable during evaluation angiography prior to RE, have a variable angioanatomic origin, and should be prophylactically occluded to prevent complications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Radiosynthesis and Biodistribution of {sup 99m}Tc-Metronidazole as an Escherichia coli Infection Imaging Radiopharmaceutical

Bacterial infection poses life-threatening challenge to humanity and stimulates to the researchers for developing better diagnostic and therapeutic agents complying with existing theranostic techniques. Nuclear medicine technique helps to visualize hard-to-diagnose deep-seated bacterial infections using radionuclide-labeled tracer agents. Metronidazole is an antiprotozoal antibiotic that serves as a preeminent anaerobic chemotherapeutic agent. The aim of this study was to develop technetium-99m-labeled metronidazole radiotracer for the detection of deep-seated bacterial infections. Radiosynthesis of {sup 99m}Tc-metronidazole was carried by reacting reduced technetium-99m and metronidazole at neutral pH for 30 min. The stannous chloride dihydrate was used as the reducing agent. At optimum radiolabeling conditions, ~ 94% radiochemical was obtained. Quality control analysis was carried out with a chromatographic paper and instant thin-layer chromatographic analysis. The biodistribution study of radiochemical was performed using Escherichia coli bacterial infection-induced rat model. The scintigraphic study was performed using E. coli bacterial infection-induced rabbit model. The results showed promising accumulation at the site of infection and its rapid clearance from the body. The tracer showed target-to-non-target ratio 5.57 ± 0.04 at 1 h post-injection. The results showed that {sup 99m}Tc-MNZ has promising potential to accumulate at E. coli bacterial infection that can be used for E. coli infection imaging.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Radiolabeled GX1 Peptide for Tumor Angiogenesis Imaging

Early and accurate detection of primary or metastatic tumors is of great value in staging, treatment management, and prognosis. Tumor angiogenesis plays an essential role in the growth, invasion, and metastatic spread of solid cancers, and so, is a promising approach for tumor imaging. The GX1 (CGNSNPKSC) peptide was identified by phage display library and has been investigated as a marker for human cancers. This study aims to evaluate the {sup 99m}Tc-HYNIC-PEG{sub 4}-c (GX1) as a biomarker for tumor imaging. Our results showed that GX1 specifically binds to tumor cells in vitro. SKMEL28 and MDA-MB231 cells achieved total binding peak at 60 min of incubation. For B16F10 and MKN45 cells, the total and specific binding were similar during all time points, while A549 cell line showed rapid cellular total uptake of the tracer at 30 min of incubation. Biodistribution showed low non-specific uptakes and rapid renal excretion. Melanoma tumors showed enhanced GX1 uptake in animal model at 60 min, and it was significantly blocked by cold peptide. The radiotracer showed tumor specificity, especially in melanomas that are highly vascularized tumors. In this sense, it should be considered in future studies, aiming to evaluate degree of angiogenesis, progression, and invasion of tumors.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Susceptibility of {sup 99m}Tc-Ciprofloxacin for Common Infection Causing Bacterial Strains Isolated from Clinical Samples: an In Vitro and In Vivo Study

{sup 99m}Tc-ciprofloxacin scintigraphy is useful in the detection of gram-positive and gram-negative bacterial infections and also for differentiating the infection from aseptic inflammation. However, due to growing bacterial resistance to antibiotics, the {sup 99m}Tc-ciprofloxacin no longer can be effective in broad-spectrum infection imaging as it is gradually losing specificity. In this study, we are presenting our findings regarding the in vitro and in vivo susceptibility of {sup 99m}Tc-ciprofloxacin for multi-drug-resistant Staphylococcus aurous, Escherichia coli, and Pseudomonas aeruginosa bacterial strains which were isolated from clinical samples. The results of radiosynthesis of {sup 99m}Tc-ciprofloxacin showed more the 95% radiochemical purity and less than 5% radioactive impurities. In vitro {sup 99m}Tc-ciprofloxacin susceptibility test showed that E. coli offered more resistant to {sup 99m}Tc-ciprofloxacin as compared to S. aurous and P. aeruginosa. In vivo study using bacterial infection induced rabbit model also revealed lowest uptake by E. coli lesion. The T/NT values were obtained 1.96 ± 0.15 in the case of E. coli; 2.81 ± 0.51 in the case of S. aurous; and 2.32 ± 0.66 in the case of P. aeruginosa at 4 h post-injection. The SPECT infection imaging of S. aurous, E. coli, and P. aeruginosa bacterial infection induced rabbit models also indicated the clear accumulation in S. aurous and P. aeruginosa lesions while negligible uptake by E. coli lesion further verify the in vitro and in vivo susceptibility profile. On the bases of the results obtained, the {sup 99m}Tc-ciprofloxacin showed selective and poor broad spectrum SPECT infection imaging.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Fast myocardial perfusion imaging with {sup 99m}Tc in challenging patients using conventional SPECT cameras

Background: We attempted to validate the performance of a fast myocardial perfusion imaging (MPI) protocol in diagnostically challenging patients. Methods: 78 patients with ΒΜΙ > 24.9, LVH or three vessels disease underwent two sequential gated-MPI studies. The first at 15 (Early Imaging, EI) and the second at 45 (Late Imaging, LI) minutes post {sup 99m}Tc-injection, at both stress and rest. Counts over heart (H), liver (Liv) and subdiaphragmatic space (Sub) and image quality, and myocardial perfusion and function parameters were compared between the two protocols. Coronary angiography was performed within 2 months from MPI, and ROC analysis was used to compare the diagnostic accuracy for the detection of ≥50% diameter luminal stenosis. Results: Quality was optimal-good in 93% of EI and 98% of LI studies (P = .12), H/Liv and stress H/Sub ratios were similar, but rest H/Sub ratio was lower in EI (P = .009). SSS [10 (0 to 46) vs 9 (0 to 36), P = .006] and SDS [3 (0 to 35) vs 2 (0 to 34), P = .02] were higher in EI protocol. LVEF, motion and thickening scores did not differ between the two protocols. A highly significant (P < .001) linear relationship with clinically negligible mean differences in Bland-Altman analysis was observed for all perfusion and function-related data. Sensitivity (EI 81%, LI 80%) and specificity (65% for both) did not differ (P = .23) between the two protocols. Conclusion: The fast protocol is technically feasible and diagnostically accurate compared to the established protocol in diagnostically challenging patients.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Validation of early image acquisitions following Tc-99 m sestamibi injection using a semiconductors camera of cadmium-zinc-telluride

Background: Cadmium-zinc-telluride (CZT) cameras allow to decrease significantly the acquisition time of myocardial perfusion imaging (MPI), but the duration of the examination is still long. Therefore, this study was performed to test the feasibility of early imaging following injection of Tc-99 m sestamibi using a CZT camera. Methods: Seventy patients underwent both an early and a delayed image acquisition after exercise stress test (n = 30), dipyridamole stress test (n = 20), and at rest (n = 20). After injection of Tc-99 m sestamibi, the early image acquisition started on average within 5 minutes for the exercise and rest groups, and 3 minutes 30 seconds for the dipyridamole group. Two independent observers evaluated image quality and extracardiac uptake on four-point scales. The difference between early and later images for each patient was scored on a five-point scale. Results: The image quality and extracardiac uptake of early and delayed image acquisitions were not different for the three groups (P > .05). There was no significant difference between early and delayed image acquisitions in the exercise, dipyridamole, and rest groups, respectively, in 63%, 40%, and 80% of cases. In the exercise group and rest group, a defect was only present in early MPI, respectively, in 13% and 20% of cases. A defect was only present in delayed images in 10% of cases in the exercise group and in 45% of cases in the dipyridamole group. Conclusions: There was no difference between early and later image acquisitions in terms of quality. This protocol reduces the length of the procedure for the patient. Beginning with early image acquisitions may help to overcome the artifacts that are observed at the delayed time.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Avoiding full corrections in dynamic SPECT images impacts the performance of SPECT myocardial blood flow quantitation

Introduction: This study investigated the performance of SPECT myocardial blood flow (MBF) quantitation lacking full physical corrections (All Corr) in dynamic SPECT (DySPECT) images. Methods: Eleven healthy normal volunteers (HVT) and twenty-four patients with angiography-documented CAD were assessed. All Corr in {sup 99m}Tc-sestamibi DySPECT encompassed noise reduction (NR), resolution recovery (RR), and corrections for scatter (SC) and attenuation (AC), otherwise no correction (NC) or only partial corrections. The performance was evaluated by quality index (R{sup 2}) and blood-pool spillover index (FBV) in kinetic modeling, and by rest flow (RMBF) and stress flow (SMBF) compared with those of All Corr. Results: In HVT group, NC diminished 2-fold flow uniformity with the most degraded quality (15%-18% reduced R{sup 2}) and elevated spillover effect (45%-50% increased FBV). Consistently higher RMBF and SMBF were discovered in both groups (HVT 1.54/2.31 higher; CAD 1.60/1.72; all P < .0001). Bland-Altman analysis revealed positive flow bias (HVT 0.9-2.6 mL/min/g; CAD 0.7-1.3) with wide ranges of 95% CI of agreement (HVT NC −1.9-7.1; NR −0.4-4.4; NR + SC −1.1-4.3; NR + SC + RR −0.7-2.5) (CAD NC −1.2-3.8; NR −1.0-2.8; NR + SC −1.0-2.5; NR + SC + RR −1.1-2.6). Conclusions: Uncorrected physical interference in DySPECT images can extensively impact the performance of MBF quantitation. Full physical corrections should be considered to warrant this tool for clinical utilization.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Clinical performance of Rb-82 myocardial perfusion PET and Tc-99m-based SPECT in patients with extreme obesity

Background: We evaluated the performance of stress imaging with technetium-99m-labeled tetrofosmin single-photon emission computed tomography (SPECT) and rubidium-82 positron emission tomography (PET) in patients with extreme obesity, defined as body mass index ≥40 kg/m{sup 2}. Methods: We identified patients with extreme obesity who underwent angiography in our center and either stress SPECT or PET within the previous six months. Cohorts of patients with extreme obesity and a <5% pretest likelihood of CAD who underwent SPECT (N = 25) or PET (N = 25) were also included. Results: In total, 108 patients who underwent SPECT (N = 57) or PET (N = 51) were identified. Scan interpretation was classified as definitely normal or abnormal in 83.3% of PET and 60.5% of SPECT scans, respectively (P < .01). PET demonstrated higher diagnostic accuracy and normalcy rate. PET was found to have higher specificity for the pooled cohort. Similar findings were observed using stenosis cut-offs of ≥50% and ≥70%. Conclusions: In patients with extreme obesity, PET enabled more definitive scan interpretation with less artifact compared to SPECT. PET provided higher diagnostic accuracy and specificity in the detection of obstructive coronary artery disease.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Prognostic study of cardiac events in Japanese patients with chronic kidney disease using ECG-gated myocardial Perfusion imaging: Final 3-year report of the J-ACCESS 3 study

Background: Myocardial perfusion imaging (MPI) is considered useful for risk stratification among patients with chronic kidney disease (CKD), without renal deterioration by contrast media. Methods and Results: The Japanese Assessment of Cardiac Events and Survival Study by Quantitative Gated SPECT (J-ACCESS 3) is a multicenter, prospective cohort study investigating the ability of MPI to predict cardiac events in 529 CKD patients without a definitive coronary artery disease. All patients were assessed by stress and rest MPI with {sup 99m}Tc-tetrofosmin and data were analyzed using a defect scoring method and QGS software. Major cardiac events were analyzed for 3 years after registration. The mean eGFR was 29.0 ± 12.8 (mL/minute/1.73 m{sup 2}). The mean summed stress/rest/difference (SSS, SRS, SDS) scores were 1.9 ± 3.8, 1.1 ± 3.0, and 0.8 ± 1.8, respectively. A total of 60 cardiac events (three cardiac deaths, six sudden deaths, five nonfatal myocardial infarctions, 46 hospitalization cases for heart failure) occurred. The event-free survival rate was lower among patients with kidney dysfunction, higher SSS, and higher CRP values. Multivariate Cox regression analysis independently associated SSS ≥8, eGFR <15 (mL/minute/1.73 m{sup 2}), and CRP ≥0.3 (mg/dL) with cardiac events. Conclusions: Together with eGFR and CRP, MPI can predict cardiac events in patients with CKD.

62 RADIOLOGY AND NUCLEAR MEDICINE↗