Single Photon Emission Computed Tomography Scans Research Articles

Structural underpinnings and long-term effects of resilience in Parkinson’s disease

Resilience in neuroscience generally refers to an individual’s capacity to counteract the adverse effects of a neuropathological condition. While resilience mechanisms in Alzheimer’s disease are well-investigated, knowledge regarding its quantification, neurobiological underpinnings, network adaptations, and long-term effects in Parkinson’s disease is limited. Our study involved 151 Parkinson’s patients from the Parkinson’s Progression Marker Initiative Database with available Magnetic Resonance Imaging, Dopamine Transporter Single-Photon Emission Computed Tomography scans, and clinical information. We used an improved prediction model linking neuropathology to symptom severity to estimate individual resilience levels. Higher resilience levels were associated with a more active lifestyle, increased grey matter volume in motor-associated regions, a distinct structural connectivity network and maintenance of relative motor functioning for up to a decade. Overall, the results indicate that relative maintenance of motor function in Parkinson’s patients may be associated with greater neuronal substrate, allowing higher tolerance against neurodegenerative processes through dynamic network restructuring.

Robustness of radiomic features in 123I-ioflupane-dopamine transporter single-photon emission computer tomography scan.

Radiomic features are usually used to predict target variables such as the absence or presence of a disease, treatment response, or time to symptom progression. One of the potential clinical applications is in patients with Parkinson's disease. Robust radiomic features for this specific imaging method have not yet been identified, which is necessary for proper feature selection. Thus, we are assessing the robustness of radiomic features in dopamine transporter imaging (DaT). For this study, we made an anthropomorphic head phantom with tissue heterogeneity using a personal 3D printer (polylactide 82% infill); the bone was subsequently reproduced with plaster. A surgical cotton ball with radiotracer (123I-ioflupane) was inserted. Scans were performed on the two-detector hybrid camera with acquisition parameters corresponding to international guidelines for DaT single photon emission tomography (SPECT). Reconstruction of SPECT was performed on a clinical workstation with iterative algorithms. Open-source LifeX software was used to extract 134 radiomic features. Statistical analysis was made in RStudio using the intraclass correlation coefficient (ICC) and coefficient of variation (COV). Overall, radiomic features in different reconstruction parameters showed a moderate reproducibility rate (ICC = 0.636, p <0.01). Assessment of ICC and COV within CT attenuation correction (CTAC) and non-attenuation correction (NAC) groups and within particular feature classes showed an excellent reproducibility rate (ICC > 0.9, p < 0.01), except for an intensity-based NAC group, where radiomic features showed a good repeatability rate (ICC = 0.893, p <0.01). By our results, CTAC becomes the main threat to feature stability. However, many radiomic features were sensitive to the selected reconstruction algorithm irrespectively to the attenuation correction. Radiomic features extracted from DaT-SPECT showed moderate to excellent reproducibility rates. These results make them suitable for clinical practice and human studies, but awareness of feature selection should be held, as some radiomic features are more robust than others.

Feasibility of myocardial blood flow quantification to detect flow-limited coronary artery disease with a one-day rest/stress continuous rapid imaging protocol on cardiac-dedicated cadmium zinc telluride single photon emission computed tomography

BackgroundIt is clinically needed to explore a more efficient imaging protocol for single photon emission computed tomography (SPECT) myocardial blood flow (MBF) quantitation derived from cadmium zinc telluride (CZT) SPECT camera for the routine clinical utilization. MethodsOne hundred and twenty patients with matched clinical characteristics and angiographic findings who completed one-day rest/stress SPECT imaging with either the intermittently sequential imaging (ISI) protocol (two dynamic and two electrocardiography (ECG)-gated scans) or the continuous rapid imaging (CRI) protocol (two dynamic/ECG-gated scans) were included. MBF quantitation adopted residual activity correction (RAC) to correct for rest residual activity (RRA) in the stress dynamic SPECT scan for the detection of flow-limited coronary artery disease. ResultsThe CRI protocol reduced about 6.2 times shorter than the ISI protocol (25.5 min vs 157.6 min), but slightly higher than the RRA (26.7% ± 3.6% vs 22.3% ± 4.9%). With RAC, both protocols demonstrated close stress MBF (2.18 ± 1.13 vs 2.05 ± 1.10, P > 0.05) and myocardial flow reserve (MFR) (2.42 ± 1.05 vs 2.48 ± 1.11, P > 0.05) to deliver comparable diagnostic performance (sensitivity = 82.1%–92.3%, specificity = 81.2%–91.2%). Myocardial perfusion and left ventricular function overall showed no significant difference (all P > 0.26). ConclusionOne-day rest/stress SPECT with the CRI protocol and rest RAC is feasible to warrant the diagnostic performance of MBF quantitation with a shortened examination time and enhanced patient comfort. Further evaluation on the impact of extracardiac activity to regional MBF and perfusion pattern is required. Additional evaluation is needed in a patient population that is typical of those referred for SPECT MPI, including those with known or suspected coronary microvascular disease.

Performance and Sensitivity of [99mTc]Tc-sestamibi Compared with Positron Emission Tomography Radiotracers to Measure P-glycoprotein Function in the Kidneys and Liver.

P-glycoprotein (P-gp, encoded in humans by the ABCB1 gene and in rodents by the Abcb1a/b genes) is a membrane transporter that can restrict the intestinal absorption and tissue distribution of many drugs and may also contribute to renal and hepatobiliary drug excretion. The aim of this study was to compare the performance and sensitivity of currently available radiolabeled P-gp substrates for positron emission tomography (PET) with the single-photon emission computed tomography (SPECT) radiotracer [99mTc]Tc-sestamibi for measuring the P-gp function in the kidneys and liver. Wild-type, heterozygous (Abcb1a/b(+/-)), and homozygous (Abcb1a/b(-/-)) Abcb1a/b knockout mice were used as models of different P-gp abundance in excretory organs. Animals underwent either dynamic PET scans after intravenous injection of [11C]N-desmethyl-loperamide, (R)-[11C]verapamil, or [11C]metoclopramide or consecutive static SPECT scans after intravenous injection of [99mTc]Tc-sestamibi. P-gp in the kidneys and liver of the mouse models was analyzed with immunofluorescence labeling and Western blotting. In the kidneys, Abcb1a/b() mice had intermediate P-gp abundance compared with wild-type and Abcb1a/b(-/-) mice. Among the four tested radiotracers, renal clearance of radioactivity (CLurine,kidney) was significantly reduced (-83%) in Abcb1a/b(-/-) mice only for [99mTc]Tc-sestamibi. Biliary clearance of radioactivity (CLbile,liver) was significantly reduced in Abcb1a/b(-/-) mice for [11C]N-desmethyl-loperamide (-47%), [11C]metoclopramide (-25%), and [99mTc]Tc-sestamibi (-79%). However, in Abcb1a/b(+/-) mice, CLbile,liver was significantly reduced (-47%) only for [99mTc]Tc-sestamibi. Among the tested radiotracers, [99mTc]Tc-sestamibi performed best in measuring the P-gp function in the kidneys and liver. Owing to its widespread clinical availability, [99mTc]Tc-sestamibi represents a promising probe substrate to assess systemic P-gp-mediated drug-drug interactions and to measure renal and hepatic P-gp function under different (patho-)physiological conditions.

Improvement of Whole-body Bone Planar Images on a Bone-dedicated Single-photon Emission Computed Tomography Scanner by Blind Deconvolution Algorithm

Purpose: We have developed a bone-dedicated collimator with higher sensitivity but slightly degraded resolution on single-photon emission computed tomography (SPECT) for planar bone scintigraphy, compared with conventional low-energy high-resolution collimator. In this work, we investigated the feasibility of using the blind deconvolution algorithm to improve the resolution of planar images on bone scintigraphy. Materials and Methods: Monte Carlo simulation was performed with the NCAT phantom for modeling bone scintigraphy on the clinical dual-head SPECT scanner (Imagine NET 632, Beijing Novel Medical Equipment Ltd.) equipped with the bone-dedicated collimator. Maximum likelihood estimation method was used for the blind deconvolution algorithm. The initial estimation of point spread function (PSF) and iteration number for the method were determined by comparing the deblurred images obtained from different input parameters. We simulated different tumors in five different locations and with five different diameters to evaluate the robustness of the initial inputs. Furthermore, we performed chest phantom studies on the clinical SPECT scanner. The quantified increased contrast ratio (CR) between the tumor and the background was evaluated. Results: The 2 mm PSF kernel and 10 iterations provided a practical and robust deblurred image on our system. Those two inputs can generate robust deblurred images in terms of the tumor location and size with an average increased CR of 21.6%. The phantom studies also demonstrated the ability of blind deconvolution, using those two inputs, with increased CRs of 17%, 17%, 22%, 20%, and 13% for lesions with diameters of 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm, respectively. Conclusions: It is feasible to use the blind deconvolution algorithm to deblur the planar images for SPECT bone scintigraphy. The appropriate values of the PSF kernel and the iteration number for the blind deconvolution can be determined using simulation studies.

Abstract A149: Characterization of HER3 targeted radioligand therapy using molecular imaging

Abstract Background: Radioligand therapy (RLT) is an emerging treatment modality that has shown potential to improve survival in cancer patients that often have limited or non-effective therapeutic options. We previously demonstrated that anti-HER3 antibody radioconjugate (HER3 ARC) has antitumor efficacy against HER3 expressing tumor xenograft models. One important step in the early development of RLT is to understand the targeting properties and the distribution of the RLT in vivo. Non-invasive molecular imaging such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) offer unique opportunities to understand drug behavior in vivo, permitting real time drug targeting and distribution analysis. In this study, we assessed the targeting properties and distribution of our HER3 ARC in HER3 expressing preclinical xenograft tumor models using both SPECT and PET. Methods: HER3 monoclonal antibody was conjugated with p-SCN-Bn-deferoxamine (DFO) or p-SCN-Bn-DOTA (DOTA) then labeled with Zirconium-89 (89Zr) or Indium-111 (111In), respectively. Flow cytometry and gamma counting was used to characterize HER3 ARC biological activity in HER3-expressing tumor cell lines. Balb/c mice subcutaneously inoculated with HER3-expressing xenograft tumors (lung, ovarian and colorectal) were intravenously administered with 89Zr-DFO-HER3 or 111In-DOTA-HER3. PET or SPECT scans were acquired 72 and 120-144hrs post injection of the radiotracer. Separate cohorts of mice were simultaneously administered with 89Zr-DFO-HER3 or 111In-DOTA-HER3 and 20-fold excess of native HER3 antibody as control to block radiotracer binding. Tissue uptake was quantified by drawing 3D or 2D regions of interest (ROI) for PET or SPECT images, respectively. Results: HER3 ARC radiotracers were successfully prepared and demonstrated similar binding to HER3 expressing cells compared to native HER3 antibody. In tumor-bearing mice, 89Zr-DFO-HER3 and 111In-DOTA-HER3 specifically accumulated in HER3 expressing tumors and cleared throughout the reticuloendothelial system. High tumor uptake was observed 120hrs post radiotracer injection using both imaging modalities. In mice pre-treated with 20-fold excess of native antibody, tumor uptake was significantly lower, showing tumor binding specificity of ARC. PET and SPECT images showed similar tracer distribution profile in the HER3 tumors. As expected, radiotracer clearance organ signals were also visualized. Conclusions: In this study we show that PET or SPECT imaging using 89Zr or 111In, respectively, offers the potential to assess the distribution of HER3 targeted radioligand therapy during early stages of drug development. HER3 ARC showed highly specific HER3 tumor uptake that remained at least 120hrs post injection. Our findings warrant further investigation to support advancement of HER3 ARC as a therapeutic option. Citation Format: Sumit Mukherjee, Debbie Lewis, Jason Li, Le-Cun Xu, Amanda Chin, Mary Chen, Monideepa Roy, Patrik Brodin, William van der Touw, Helen Kotanides, Denis Beckford-Vera. Characterization of HER3 targeted radioligand therapy using molecular imaging [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A149.

Variability in expenses related to spine oncology care: comparison of payer-negotiated rates at National Cancer Institute-Designated Cancer Centers

BACKGROUNDAs of 2021, the Centers for Medicare and Medicaid Services (CMS) requires all hospitals to publish their commercially negotiated prices. To our knowledge, price variation of spine oncology diagnosis and treatments has not been previously investigated. PURPOSEThe aim of this study is to characterize the availability and variation of prices for spinal oncology services among National Cancer Institute-Designated Cancer Centers (NCI-DCC). STUDY DESIGNCross-sectional analysis. METHODSCancer centers were identified; those that did not provide patient care or participate in Medicare's Inpatient Prospective System were excluded. A cross-sectional analysis was conducted to gather commercially negotiated prices by searching online for “[center name] price transparency OR machine-readable file OR chargemaster.” Data obtained was queried using 44 current procedural terminology (CPT) codes for imaging, procedures, and surgeries relevant to spine oncology. Comparison of prices was achieved by normalizing the median price for each service at each center to the estimated 2022 Medicare reimbursement for the center's Medicare Administrator Contractor. The ratios between the lowest and highest median commercial negotiated price within a center and across all centers were defined as “within-center ratio” and “across-center ratio” respectively. RESULTSIn total, 49 centers disclosed commercial payer-negotiated rates. Mean rate (±SD) for cervical corpectomy was $9,134 (±$10,034), thoracic laminectomy for neoplasm excision was $5,382 (±$5502), superficial bone biopsy was $1,853 (±$1,717), and single-photon emission computerized tomography (SPECT) was $813 (±$232). Within-center ratios ranged from 5.0 (SPECT scan) to 17.8 (radiofrequency bone ablation). Across-center ratios (for codes with > 10 centers reporting) ranged from 9.0 (corpectomy, thoracic, lateral extra-cavitary) to 418.7 (anterior approach cervical corpectomy). CONCLUSIONSPrice transparency for spinal oncology remains elusive despite recent CMS regulatory oversight, with marked heterogeneity in the quality of published rates complicating patients' ability to “shop” for care. Additionally, there continues to be significant variation in commercial rates for spine oncology diagnosis and treatment. CLINICAL SIGNIFICANCEDespite regulation by CMS, prices for spinal oncology services are not uniformly available to patients and vary between NCI-DCC. The findings of this manuscript present potential barriers for patients to compare and obtain affordable care.

The clinical effectiveness of fused image of single-photon emission CT and facial CT for the evaluation of degenerative change of mandibular condylar head

BackgroundThe primary objective of this study was to assess the clinical effectiveness of fused images obtained from single-photon emission computed tomography (SPECT) and facial computed tomography (CT) for evaluating degenerative changes in the mandibular condylar head. This assessment was accomplished by comparing the Technetium-99 m methylene diphosphonate (99mTc-MDP) uptake ratio with the results of clinical and radiographic findings.MethodsThe study included 17 patients (3 males and 14 females) with suspected osteoarthritis of the mandibular condyle, totaling 34 temporomandibular joints (TMJs). Based on clinical and radiographic examinations, the TMJs were categorized into four groups: normal (group N), internal derangement (group ID), osteoarthritis (group OA), and osteoarthritis sequelae (group OAseq). For each patient, bone SPECT and facial CT scans were registered and reconstructed to create fused SPECT/CT images. The 99mTc-MDP uptake levels in the TMJs were statistically compared among the four groups.ResultsThe 99mTc-MDP uptake ratio showed a gradual increase in the order of the following: group N, group OAseq, group ID, and group OA. There was a significant difference observed among groups (p = 0.003), mainly driven by the disparity between group OA and both group N (p < 0.001) and group OAseq (p = 0.048).ConclusionFused SPECT/CT image can be an effective tool for evaluating degenerative changes in the mandibular condylar head. The technique demonstrated the ability to differentiate between normal TMJs and those with internal derangement, osteoarthritis, or osteoarthritis sequelae. This approach holds promise as a valuable method in clinical assessments of TMJ degeneration.

Dopamine Transporter Availability in Early Parkinson's Disease is Dependent on Sunlight Exposure.

Preliminary studies suggested seasonality of dopaminergic functioning, but it is unknown whether dopamine transporter (DAT) expression in humans is also dependent on the seasons. We, therefore, investigated seasonal and sunlight-dependent effects on DAT availability in early Parkinson's disease (PD) patients and healthy controls. DAT single-photon emission computed tomography scans (n = 730) were gathered from the Parkinson's Progression Marker Initiative (PPMI) database. We used global horizontal irradiance (GHI) as proxy for sun exposure/month and assessed associations between striatal DAT availability and season (autumn/winter versus spring/summer), GHI and latitude of the PPMI site. In PD patients, DAT availability in the left caudate nucleus was higher in spring/summer (B [standard error (SE)] = 0.05 [0.02], P = 0.03) and positively associated with higher sun exposure (B [SE] = 0.59 [0.22] × 10-3 , P = 0.007). Latitude (in degrees north) of the PPMI site was negatively associated with DAT availability in both PD and healthy controls. Striatal DAT availability may be influenced by daylight exposure. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Modified Exigent Features Block in JAN Net for Analysing SPECT Scan Images to Diagnose Early-Stage Parkinson's Disease.

The quantitative measure of dopamine transporter (DaT) in the human midbrain is generally used as a biomarker for analyzing Parkinson's disease (PD). DaT scan images or Single- photon emission computed tomography (SPECT) images are utilized to capture the dopamine content more accurately. Only sixteen slices out of ninety-one of SPECT images were chosen on the basis of the high amount of dopamine content and were named Volume rendering image slices (VRIS). This paper proposes a novel Convolutional Neural Network (CNN) called JAN Net which particularly treats the VRIS for identifying PD. The JAN Net preserves the edges and spatial features of the striatum by using a modified exigent feature (M-ExFeat) block, that contains convolutional and additive layer. The different-sized convolutional layer extracts both low- and high-level features of Striatum. The additive layer adds up all the features of different filter sized convolutional layers like 1x1, 3x3, and 5x5. The added output features are used to improve the learnability of neurons in the hidden layer. The network performance is tested for stride 1 and stride 2. The results are validated using the dataset taken from the Parkinson's Progression Markers Initiative (PPMI) database. The JAN Net ensures improved performance in terms of accuracy. The training and validation accuracy for stride 2 is 100% with minimum losses. The outcome has been compared with different deep learning architectures and the machine learning techniques like Extreme Learning Machines (ELM), and Artificial Neural Networks (ANN) to highlight the efficacy of the proposed architecture. Hence, the present work could be of great aid to the experts in neurology to protect the neurons from impairment.

DuSFE: Dual-Channel Squeeze-Fusion-Excitation co-attention for cross-modality registration of cardiac SPECT and CT.

Myocardial perfusion imaging (MPI) using single-photon emission computed tomography (SPECT) is widely applied for the diagnosis of cardiovascular diseases. Attenuation maps (μ-maps) derived from computed tomography (CT) are utilized for attenuation correction (AC) to improve the diagnostic accuracy of cardiac SPECT. However, in clinical practice, SPECT and CT scans are acquired sequentially, potentially inducing misregistration between the two images and further producing AC artifacts. Conventional intensity-based registration methods show poor performance in the cross-modality registration of SPECT and CT-derived μ-maps since the two imaging modalities might present totally different intensity patterns. Deep learning has shown great potential in medical imaging registration. However, existing deep learning strategies for medical image registration encoded the input images by simply concatenating the feature maps of different convolutional layers, which might not fully extract or fuse the input information. In addition, deep-learning-based cross-modality registration of cardiac SPECT and CT-derived μ-maps has not been investigated before. In this paper, we propose a novel Dual-Channel Squeeze-Fusion-Excitation (DuSFE) co-attention module for the cross-modality rigid registration of cardiac SPECT and CT-derived μ-maps. DuSFE is designed based on the co-attention mechanism of two cross-connected input data streams. The channel-wise or spatial features of SPECT and μ-maps are jointly encoded, fused, and recalibrated in the DuSFE module. DuSFE can be flexibly embedded at multiple convolutional layers to enable gradual feature fusion in different spatial dimensions. Our studies using clinical patient MPI studies demonstrated that the DuSFE-embedded neural network generated significantly lower registration errors and more accurate AC SPECT images than existing methods. We also showed that the DuSFE-embedded network did not over-correct or degrade the registration performance of motion-free cases. The source code of this work is available at https://github.com/XiongchaoChen/DuSFE_CrossRegistration.

Virtual reality-based training and pre-operative planning for head and neck sentinel lymph node biopsy

ObjectiveSentinel lymph node biopsy (SLNB) is crucial for managing head and neck skin cancer. However, variable lymphatic drainage can complicate SLN detection when using Single-Photon Emission Computed Tomography (SPECT) or lymphoscintigraphy. Virtual Reality (VR) can contribute to pre-operative planning by simulating a realistic 3D model, which improves orientation. VR can also facilitate real-patient training outside the operating room. This study explored using a VR platform for pre-operative planning in head and neck skin cancer patients undergoing SLNBs and assessed its value for residential training. Materials and methodsIn this prospective technology pilot study, attending surgeons and residents who performed 21 SLNB operations on patients with head and neck skin cancers (81% males, mean age 69.2 ± 11.3) used a VR simulation model based on each patient's pre-operative SPECT scan to examine patient-specific anatomy. After surgery, they completed a questionnaire on the efficiency of the VR simulation as a pre-operative planning tool and training device for residents. ResultsThe attending surgeons rated the VR model's accuracy at 8.3 ± 1.6 out of 10. Three-quarters (76%) of residents reported increased confidence after using VR. The physicians rated the platform's contribution to residents' training at 7.4 ± 2.1 to 8.9 ± 1.3 out of 10. ConclusionA VR SLNB simulation can accurately portray marked sentinel lymph nodes. It was rated high as a surgical planning and teaching tool among attending surgeons and residents alike and may play a role in pre-operative planning and resident training. Further studies are needed to explore its applications in practice.

Theranostic Surrogacy of [123I]NaI for Differentiated Thyroid Cancer Radionuclide Therapy.

Precise dosimetry has gained interest for interpreting the response assessments of novel therapeutic radiopharmaceuticals, as well as for improving conventional radiotherapies such as the "one dose fits all" approach. Although radioiodine as same-element isotope theranostic pairs has been used for differentiated thyroid cancer (DTC), there are insufficient studies on the determination of its dosing regimen for personalized medicine and on extrapolating strategies for companion diagnostic radiopharmaceuticals. In this study, DTC xenograft mouse models were generated after validating iodine uptakes via sodium iodine symporter proteins (NIS) through in vitro assays, and theranostic surrogacy of companion radiopharmaceuticals was investigated in terms of single photon emission computed tomography (SPECT) imaging and voxel-level dosimetry. Following a Monte Carlo simulation, the hypothetical energy deposition/dose distribution images were produced as [123I]NaI SPECT scans with the use of 131I ion source simulation, and dose rate curves were used to estimate absorbed dose. For the tumor, a peak concentration of 96.49 ± 11.66% ID/g occurred 2.91 ± 0.42 h after [123I]NaI injection, and absorbed dose for 131I therapy was estimated as 0.0344 ± 0.0088 Gy/MBq. The absorbed dose in target/off-target tissues was estimated by considering subject-specific heterogeneous tissue compositions and activity distributions. Furthermore, a novel approach was proposed for simplifying voxel-level dosimetry and suggested for determining the minimal/optimal scan time points of surrogates for pretherapeutic dosimetry. When two scan time points were set to Tmax and 26 h and the group mean half-lives were applied to the dose rate curves, the most accurate absorbed dose estimates were determined [-22.96, 2.21%]. This study provided an experimental basis to evaluate dose distribution and is expected hopefully to improve the challenging dosimetry process for clinical use.

Temporalis Myofascial Flap and Conchal Bowl Cartilage Grafting for Temporomandibular Joint Arthritis

Temporomandibular joint (TMJ) arthritis arises from a multitude of etiologies; however, there is no consensus definitive treatment. The complication profile of artificial TMJs is well known, and outcomes are variable and are reserved for salvage attempts. This case details a patient with persistent traumatic TMJ pain, arthritis, and single-photon emission computed tomography scan of potential nonunion. The present study reports on the first novel use of an alternative composite myofascial flap to help arthritic TMJ pain. This study details the successful use of a temporalis myofascial flap and conchal bowl autologous cartilage graft in posttraumatic TMJ degeneration.

Simulation studies of a full-ring, CZT SPECT system for whole-body imaging of 99m Tc and 177 Lu.

Single photon emission computed tomography (SPECT) is an imaging modality that has demonstrated its utility in a number of clinical indications. Despite this progress, a high sensitivity, high spatial resolution, multi-tracer SPECT with a large field of view suitable for whole-body imaging of a broad range of radiotracers for theranostics is not available. With the goal of filling this technological gap, we have designed a cadmium zinc telluride (CZT) full-ring SPECT scanner instrumented with a broad-energy tungsten collimator. The final purpose is to provide a multi-tracer solution for brain and whole-body imaging. Our static SPECT does not rely on the dual- and the triple-head rotational SPECT standard paradigm, enabling a larger effective area in each scan to increase the sensitivity. We provide a demonstration of the performance of our design using a realistic model of our detector with simulated body-sized phantoms filled with 99m Tc and 177 Lu. We create a realistic model of our detector by using a combination of a Geant4 Application for Tomographic Emission (GATE) Monte Carlo simulation and a finite element model for the CZT response, accounting for low-energy tail effects in CZT that affects the sensitivity and the scatter correction. We implement a modified dual-energy-window scatter correction adapted for CZT. Other corrections for attenuation, detector and collimator response, and detector gaps and edges are also included. The images are reconstructed using the maximum-likelihood expectation-maximization. Detector and reconstruction performance are characterized with point sources, Derenzo phantoms, and a body-sized National Electrical Manufacturers Association (NEMA) Image Quality (IQ) phantom for both 99m Tc and 177 Lu. Our SPECT design can resolve 7.9mm rods for 99m Tc (140keV) and 9.5mm for 177 Lu (208keV) in a hot-rod Derenzo phantom with a 3-min exposure and reach an image contrast of 78% for 99m Tc and 57% for 177 Lu using the NEMA IQ phantom with a 6-min exposure. Our modified scatter correction shows an improved contrast-recovery ratio compared to a standard correction. In this paper, we demonstrate the good performance of our design for whole-body imaging purposes. This adds to our previous demonstration of improved qualitative and quantitative 99m Tc imaging of brain perfusion and 123 I imaging of dopamine transport with respect to state-of-the-art NaI dual-head cameras. We show that our design provides similar IQ and contrast to the commercial full-ring SPECT VERITON for 99m Tc. Regarding 177 Lu imaging of the 208keV emissions, our design provides similar contrast to that of other state-of-the-art SPECTs with a significant reduction in exposure. The high sensitivity and extended energy range up to 250keV makes our SPECT design a promising alternative for clinical imaging and theranostics of emerging radionuclides.

Prognostic value of coronary computed tomography angiography compared to radionuclide myocardial perfusion imaging in patients With coronary stents.

The aim of this study is to compare the prognostic value of coronary computed tomography angiography (CCTA) with single-photon emission computed tomography (SPECT) in predicting cardiovascular events in patients with stents. Retrospective analysis. University Hospital, London, Ontario Canada. Between January 2007 and December 2018, 119 patients post-percutaneous coronary intervention (PCI) who were referred for hybrid imaging with CTA and 2-day rest/stress SPECT were enrolled. Patients were followed for any major adverse cardiovascular event (MACE) including: All-cause mortality, Non-fatal myocardial infarction (MI), Unplanned revascularization, Cerebrovascular accident and hospitalization for arrhythmia or heart failure. We define hard cardiac events (HCE) as: cardiac death, non-fatal MI or unplanned revascularization. We used two cut-off values to define obstructive lesions with CCTA ≥50% and ≥70% in any coronary segment. SPECT scan defined as abnormal in the presence of >5% reversible myocardial perfusion defect. During the follow-up period of 7.2 ± 3.4 years. 45/119 (37.8%) patients experienced 57 MACE: Ten deaths (2 cardiac deaths and 8 of non-cardiac deaths), 29 acute coronary syndrome including non-fatal MI (25 required revascularization), 7 hospitalizations for heart failure, 6 cerebrovascular accidents and 5 new atrial fibrillation. 31 HCEs were reported. Cox regression analysis showed that obstructive coronary stenosis (≥50% and ≥70%) and abnormal SPECT were associated of MACE (p = 0.037, 0.018 and 0.026), respectively. In contrast, HCEs were significantly associated with obstructive coronary stenosis of ≥50% and ≥70% with p = 0.004 and p = 0.007, respectively. In contrast, abnormal SPECT was a nonsignificant predictor of HCEs (p = 0.062). Obstructive coronary artery stenosis on CCTA can predict MACE and HCE. However, abnormal SPECT can only predict MACE but not HCE in patients post-PCI with a follow-up period of approximately 7 years.

An Iterative Based Motion Correction for SPECT with Simulated Data

Purpose: Single Photon Emission Computed Tomography (SPECT) is one of the important imaging modality in nuclear medicine used for diagnostic imaging of different organs of human body. Patient movement during the acquisition time is a well-known cause of artifacts in reconstructed SPECT data. These motion artifacts may significantly affect the diagnostic accuracy. Therefore, the motion correction of patients in tomography images is very much essential for more accurate diagnosis and hence achieves the quality of the images. Objective: The aim of this project is to develop and evaluate a data driven approach to motion correction without necessity for motion tracking system. Methods: It has been proposed a method to iteratively estimate and compensate this motion during the reconstruction. The rigid motion was estimated view-by-view in every iteration and then used to update the system matrix. The initial reconstructed image is motion contaminated; it can be used to generate a first rough motion estimate. This motion is taken into account in a reconstruction process to generate a motion-corrected image at the first iteration. Then the motion-corrected image and the motion estimate are alternately updated to increase the likelihood, the iterations are stopped when the updated motion seems to have converged. The image update is done by applying multiple iterations of the OSEM algorithm. A final iterative reconstruction was performed with the last motion estimate. Results: The method was evaluated on simulations phantom study. From the simulations phantom data, we produced the several simulated motion induced data. Motion correction algorithms were applied with the simulated motion induced data. The quality of the reconstructed images was improved substantially after the compensation. Mean structural similarity was increased. In the simulation studies, most of the motion blurring in the reconstructed images disappeared after the compensation. Conclusions: The proposed method effectively eliminated motion-induced artifacts in SPECT scans. Since only measured raw data are needed for the motion estimation and compensation, the proposed method can be applied retrospectively to SPECT scans affected by motion. Bangladesh J. Nuclear Med. 26(1): 19-24, 2023

99m-Tc TRODAT Single-Photon Emission Computerized Tomography Scan Image Compression using Singular Value Decomposition.

The objective of the study was to compress 99m-Tc TRODAT single-photon emission computerized tomography (SPECT) scan image using Singular Value Decomposition (SVD) into an acceptable compressed image and then calculate the compression factor. The SVD of every image from the image dataset of 2256 images (of forty-eight 99m-Tc TRODAT SPECT studies [48 studies X 47 trans-axial images = 2256 trans-axial images]) was computed and after truncating singular values smaller than a threshold, the compressed image was reconstructed. The SVD computation time and percentage compression achieved were calculated for each image. Two nuclear medicine physicians visually compared compressed image with its original image, and labeled it as either acceptable or unacceptable. Compressed image having loss of clinical details or presence of compression artifact was labeled unacceptable. The quality of compressed image was also assessed objectively using the following image quality metrics: Error, structural similarity (SSIM), brightness, global contrast factor (GCF), contrast per pixel (CPP), and blur. We also compared the TRODAT uptake in basal ganglia estimated from the compressed image and original image. Nuclear Medicine Physician labeled each image acceptable, as they found compressed image identical to its original image. The values of brightness, GCF, CPP, and blur metrics show that compressed images are less noisy, brighter, and sharper than its original image. The median values of error (0.0006) and SSIM (0.93) indicate that the compressed images were approximately identical to its original image. In 39 out of 48 studies, the percentage difference in TRODAT uptake (in basal ganglia from compressed and original image) was negligible (approximately equal to zero). In remaining 9 studies, the maximum percentage difference was 13%. The SVD computation time and percentage compression achieved for a TRODAT study were 0.17398 s and up to 54.61%, respectively. The compression factor up to 54.61% was achieved during 99m-Tc TRODAT SPECT scan image compression using SVD, for an acceptable compressed image.

Impact of Positron Emission Tomography Viability Imaging: Guided Revascularizations on Clinical Outcomes in Patients With Myocardial Scar on Single-Photon Emission Computed Tomography Scans.

Positron emission tomography (PET) viability scan is used to determine whether patients with a myocardial scar on single-photon emission computed tomography (SPECT) may need revascularization. However, the clinical utility of revascularization decision-making guided by PET viability imaging has not been proven yet. The purpose of this study was to investigate the impact of PET to determine revascularization on clinical outcomes. Between September 2012 and May 2021, 53 patients (37 males; mean age = 64 ± 11 years) with a myocardial scar on MIBI SPECT who underwent PET viability test were analyzed in this study. The primary outcome was a temporal change in echocardiographic findings. The secondary outcome was all-cause mortality. Viable myocardium was presented by PET imaging in 29 (54.7%) patients. Revascularization was performed in 26 (49.1%) patients, including 18 (34.0%) with percutaneous coronary intervention (PCI) and 8 (15.1%) with coronary artery bypass grafting. There were significant improvements in echocardiographic findings in the revascularization group and the viable myocardium group. All-cause mortality was significantly lower in the revascularization group than in the medical therapy-alone group (19.2% vs. 44.4%, log-rank P = 0.002) irrespective of viable (21.4% vs. 46.7%, log-rank P = 0.025) or non-viable myocardium (16.7% vs. 41.7%, log-rank P = 0.046). All-cause mortality was significantly lower in the PCI group than in the medical therapy-alone group (11.1% vs. 44.4%, log-rank P < 0.001). Revascularization improved left ventricular systolic function and survival of patients with a myocardial scar on SPECT scans, irrespective of myocardial viability on PET scans.

Afasia cruzada em paciente canhota com afasia progressiva primária variante não fluente com SPECT cerebral assimétrico à esquerda

ABSTRACT Primary progressive aphasia is a clinical syndrome caused by neurodegeneration of areas and neural networks involved in language, usually in the left hemisphere. The term “crossed aphasia” denotes an acquired language dysfunction caused by a lesion in the ipsilateral hemisphere to the dominant hand. Objective: To describe a case of crossed aphasia in a 60-year-old left-handed patient with a non-fluent variant of primary progressive aphasia diagnosis (age of onset=52), evidenced by a left asymmetry on brain SPECT scan. Methods: Clinical and family history, the Edinburgh Handedness Inventory, Measurement of Functional Activities in Older Adults in the Community, the “Mini-Mental State Examination”, the Trail Making Test, the Tower of London, and the Neuropsychological assessment for dementia, and neuroimaging studies were carried out. Results: Neuropsychological assessment showed severe cognitive impairment, especially regarding language. The magnetic resonance imaging showed important signs of cortico-subcortical atrophy, with predominance in the frontal and temporal lobes. The single-photon emission computed tomography scan showed moderate to severe hypoperfusion in the left cerebral hemisphere, including the hippocampus. Conclusion: We described a clinical case of crossed aphasia in a left-handed woman with a non-fluent variant of primary progressive aphasia with asymmetry on brain SPECT, mainly on the left, followed up for seven years.