Single Photon Emission Computed Tomography Research Articles

Emerging Role of Prefrontal Lobe Involving Visual Function in a Case with Whiplash-Associated Disorders

Whiplash, often resulting from vehicle accidents, can cause bony or soft tissue injuries leading to clinical symptoms related to the cervical spine or brain. However, diagnosing whiplash objectively is challenging, as acute phase abnormalities in the cervical spine or brain are difficult to detect through anatomic/ structural imaging. We present a case of a 54-year-old woman suffering from Whiplash-Associated Disorder (WAD) without abnormal structural abnormalities. Using brain perfusion single-photon emission computed tomography (SPECT) to measure regional cerebral blood flow, hypoperfusion was observed in the bilateral prefrontal regions and parietal/occipital lobes, which was associated with her visual impairment. We support the nociceptive-vascular hypothesis and propose an additional role for the prefrontal lobe in contributing to WAD in patients following whiplash injury. Further investigation is needed to monitor the effects of brain perfusion after treatment using SPECT.

Myocardial perfusion SPECT radiomic features reproducibility assessment: Impact of image reconstruction and harmonization.

Coronary artery disease (CAD) has one of the highest mortality rates in humans worldwide. Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) provides clinicians with myocardial metabolic information non-invasively. However, there are some limitations to interpreting SPECT images performed by physicians or automatic quantitative approaches. Radiomics analyzes images objectively by extracting quantitative features and can potentially reveal biological characteristics that the human eye cannot detect. However, the reproducibility and repeatability of some radiomic features can be highly susceptible to segmentation and imaging conditions. We aimed to assess the reproducibility of radiomic features extracted from uncorrected MPI-SPECT images reconstructed with 15 different settings before and after ComBat harmonization, along with evaluating the effectiveness of ComBat in realigning feature distributions. A total of 200 patients (50% normal and 50% abnormal) including rest and stress (without attenuation and scatter corrections) MPI-SPECT images were included. Images were reconstructed using 15 combinations of filter cut-off frequencies, filter orders, filter types, reconstruction algorithms, number of iterations and subsets resulting in 6000 images. Image segmentation was performed on the left ventricle in the first reconstruction for each patient and applied to 14 others. A total of 93 radiomic features were extracted from the segmented area, and ComBat was used to harmonize them. The intraclass correlation coefficient (ICC) and overall concordance correlation coefficient (OCCC) tests were performed before and after ComBat to examine the impact of each parameter on feature robustness and to assess harmonization efficiency. The ANOVA and the Kruskal-Wallis tests were performed to evaluate the effectiveness of ComBat in correcting feature distributions. In addition, the Student's t-test, Wilcoxon rank-sum, and signed-rank tests were implemented to assess the significance level of the impacts made by each parameter of different batches and patient groups (normal vs. abnormal) on radiomic features. Before applying ComBat, the majority of features (ICC: 82, OCCC: 61) achieved high reproducibility (ICC/OCCC ≥ 0.900) under every batch except Reconstruction. The largest and smallest number of poor features (ICC/OCCC<0.500) were obtained by IterationSubset and Order batches, respectively. The most reliable features were from the first-order (FO) and gray-level co-occurrence matrix (GLCM) families. Following harmonization, the minimum number of robust features increased (ICC: 84, OCCC: 78). Applying ComBat showed that Order and Reconstruction were the least and the most responsive batches, respectively. The most robust families, in a descending order, were found to be FO, neighborhood gray-tone difference matrix (NGTDM), GLCM, gray-level run length matrix (GLRLM), gray-level size zone matrix (GLSZM), and gray-level dependence matrix (GLDM) under Cut-off, Filter, and Order batches. The Wilcoxon rank-sum test showed that the number of robust features significantly differed under most batches in the Normal and Abnormal groups. The majority of radiomic features show high levels of robustness across different OSEM reconstruction parameters in uncorrected MPI-SPECT. ComBat is effective in realigning feature distributions and enhancing radiomic features reproducibility.

Advancements in colorectal cancer detection: The role of immuno‐positron emission tomography, immuno‐single‐photon emission computed tomography, and machine learning applications

AbstractColorectal cancer (CRC) ranks as the world's second most prevalent cancer and third in mortality. Detection and diagnosis are crucial in research and clinical settings. While colonoscopy and computed tomographic colonography are widely used for identifying organic lesions, positron emission tomography (PET) and single‐photon emission computed tomography (SPECT) offer superior visualization of molecular changes. These immuno‐PET and immuno‐SPECT techniques surpass conventional [18F] Fluorodeoxyglucose PET/CT in specificity and sensitivity, improving CRC diagnostics and supporting therapeutic strategies. This review emphasizes the role of immuno‐PET/SPECT in CRC diagnosis and establishing a foundation for therapeutic strategies, facilitating hierarchical management through the identification of treatment‐responsive populations, prediction of therapeutic outcomes, and support for intraoperative imaging. This review introduces the preclinical and clinical utility of immunoconjugates for detecting colorectal adenomas, and primary, metastatic, or recurrent CRC, focusing on specific CRC cell targets like the epidermal growth factor receptor and carcinoembryonic antigen. The review also covers various mAb‐based immunoconjugates and engineered mAb fragments, including diabodies and minibodies. Finally, it looks into the great promise of machine learning in PET or SPECT and it addresses the challenges of translating preclinical successes into clinical practice for colorectal adenoma diagnosis, proposing potential solutions and directions for future research.

Feasibility of quantitative evaluation of hemodynamics using SPECT/CT in patients with chronic thromboembolic pulmonary hypertension

Abstract Background A ventilation/perfusion (V/Q) lung scan is recommended in the diagnostic work-up of patients with newly diagnosed pulmonary hypertension to rule out chronic thromboembolic pulmonary hypertension (CTEPH). V/Q single-photon emission computed tomography (SPECT) is considered the method of choice for diagnosis in CTEPH because it allows more precise evaluation than planar imaging. However, the evaluation of lung perfusion using V/Q SPECT imaging remains mainly a qualitative evaluation, and no quantitative method has been established. We hypothesized that the standardized uptake value (SUV) technique in Positron Emission Tomography (PET)-CT, a nuclear imaging technique well suited for quantitative of tumor biology, could be applied to quantitative assessment of lung perfusion. Purpose The purpose of this study was to evaluate the correlation between pulmonary perfusion distribution and hemodynamic data in Tc-labeled large-assembly albumin (99mTc-MAA) SPECT images in order to determine the feasibility of SPECT/CT for quantitative assessment of lung perfusion. Methods Twenty-five patients with CTEPH who underwent BPA and received SPECT-CT were included. Since the injected 99mTc-MAA selectively accumulates only in the lungs, SUV normalization was conducted using each patient’s lung volume, calculated by SPECT/CT and defined as SUV lung volume (LV) . The percentage of lung volume below each SUVLV value in total lung volume on SPECT/CT was examined before BPA, after two procedures of BPA, and six months after a series of BPA, and the correlations with hemodynamic parameters on right heart catheterization at each time point were evaluated. Results The Percent lung volume below SUVLV of 0.7 in total lung volume before BPA, after two procedures of BPA, and six months after a series of BPA had the strongest correlation with mean pulmonary artery pressure (mPAP) (rs; 0.727, p&amp;lt;0.001, Figure 1). The percent lung volume below SUVLV of 0.7 decreased with the BPA procedure in each patient with CTEPH (Figure 2). Furthermore, receiver operating characteristic analysis revealed that a threshold for the percent lung volume below SUVLV of 0.7 of 50.3% or greater could identify mPAP greater than 21 mmHg for right heart catheterization (area under the curve = 0.86, 95% CI 0.78-0.94, p&amp;lt;0.001). Conclusion Percent lung volume below SUVLV of 0.7 in total lung volume using SPECT/CT might reflect the severity of hemodynamics in patients with CTEPH. This method would be feasible for quantitative assessment of lung perfusion, even inter-patient and intra-patient.Figure 1Figure 2

Cardiac sympathetic innervation, assessed with 123I-MIBG SPECT, predicts left ventricular function improvement in patients with newly diagnosed dilated cardiomyopathy

Abstract Introduction Beta-blockers (BB) are commonly prescribed medications for heart failure (HF) due to their ability to counteract the increased sympathetic nervous system (SNS) activity seen in HF, resulting in downregulation and desensitization of β-receptors. In patients with dilated cardiomyopathy (DCM), the introduction of BB therapy can lead to left ventricular ejection fraction (LVEF) improvement in 30-50% of cases. Single-photon emission computed tomography (SPECT) with 123I-meta-iodobenzylguanidine (MIBG) is a useful tool for assessing cardiac SNS activity. Healthy individuals typically exhibit high SPECT-MIBG uptake and low washout rate (WR) due to normal β-receptor levels and low norepinephrine (NE) levels, respectively (Fig 1A). While better SPECT-MIBG results have been associated with LVEF improvement in the general HF population, less data is available for DCM patients. Purpose This study aimed to evaluate the predictive value of MIBG-SPECT for LVEF improvement in newly diagnosed DCM patients. Methods Twenty-one DCM patients (mean age 47 ± 10 years, 90% male, baseline LVEF 29.5 ± 8.7%, left ventricular end-diastolic volume (LVEDV) 114 ± 36 ml/m2) with stable HF symptoms (NYHA class 1.8 ± 0.6) and newly diagnosed DCM underwent baseline MIBG-SPECT and echocardiography. HF therapy was initiated and up-titrated, and echocardiography was repeated at 6 months. Semi-quantitative parameters from MIBG-SPECT, including the MIBG uptake ratio from the heart and mediastinum (H/M) at 15 minutes (-15) and 4 hours (-4), as well as the WR [WR = (H/M-15 - H/M-4) / H/M-15], were evaluated. Patients were stratified based on median WR - 8.79 (IQR 5.17-12.90). Results After 6-months of HF therapy up-titration, 18 patients improved LVEF, and the mean LVEF increase was 7.7 ± 10.4%. Although, patients with WR &amp;gt; median did not differ in terms of baseline LVEF (30.2 ± 7.0 vs. 27.7 ± 9.6, p=0.52), they had worse LVEF at 6 months (32.0 ± 11.0 vs. 40.6 ± 9.2%, p=0.04). Moreover, WR at baseline strongly correlated with 6-month LVEF (R=-0.51, p=0.01) and was a significant predictor of 6-month LVEF (β=-0.55 ± 0.19, p=0.009). Moreover, WR could successfully predict LVEF improvement ≥ 10% (OR 1.27 [95%CI 1.01-1.61], p=0.03; AUC 0.82 [95%CI 0.63-0.99], p&amp;lt;0.001) with a cut-off point of 8.0 (sensitivity 88%, specificity 77%) (Fig 1B). Conclusion Most DCM patients demonstrated LVEF improvement during 6 months of HF therapy up-titration. Baseline WR from MIBG-SPECT was found to be a reliable predictor of significant LVEF improvement in this patient population.Fig1.A-SPECT-MIBG results. B-ROC curve.

Impact of a new coronavirus infection on the level of inflammatory, haemostasis markers and microcirculatory parameters of patients with arterial hypertension

Relevance. The COVID-19 pandemic and its consequences have significantly affected the health of the population as a whole. Persons who have undergone coronavirus infection against the background of chronic cardiovascular diseases and obesity deserve special attention. Aim. To study and compare the main indicators of carbohydrate and lipid metabolism the level of inflammatory and haemostasis markers, microvascular changes in obesity AH patients and in AH patients with normal body weight 1 month after a new coronavirus infection in moderate to severe form. Materials and methods. The study included 87 patients of both sexes, aged from 18 to 55 years, from which three groups were formed: the first group included people with AH and normal body weight (BMI&lt;25 kg/m²) who had undergone COVID-19 within a month, the second group included people with AH and obesity (BMI≥30 kg/m²) who had undergone COVID-19 within a month, the control group consisted of 20 people with AH and obesity without COVID-19. The parameters of height, weight, waist circumference, and BMI were assessed in all subjects. The parameters of lipid profile, glucose level were determined, inflammatory markers and haemostasis parameters. All participants underwent laser Doppler flowmetry (LDF) on the forearm with constrictor and dilator functional tests, and single-photon emission computed tomography (SPECT) in combination with x-ray computed tomography (SPECT/CT). Results. Patients of groups 1 and 2 naturally differed from each other in anthropometric indicators. Lipid and carbohydrate metabolism rates were also significantly higher in group 2 patients compared to group 1 patients (p &lt; 0.05). The CRP level in the group of people with hypertension and obesity who underwent COVID-19 was significantly higher than in people with hypertension without obesity (p &lt; 0.001) and than in people with hypertension and obesity without a history of COVID-19. When comparing microcirculation parameters by LDF, there was a decrease in tissue hemoperfusion (M), blood flow reserve (RK) in all three groups (p &lt; 0.001), the most pronounced dysfunction of neurogenic and myogenic blood flow regulation was detected in the group of people with hypertension andobesity who underwent COVID-19. Conclusion. The study of microcirculation indicators by LDF method in persons with hypertension and obesity after suffering a coronavirus infection indicates the predominance of the spastic type of microcirculation, which, together with an increase in the levels of inflammatory markers, indicates a higher risk of thrombosis and cardiovascular complications, requiring more careful monitoring and treatment of this group of patients.

Impact of CT attenuation correction on viable myocardium detection in combined SPECT and PET/CT: A retrospective cohort study.

The influence of computed tomography attenuation correction (CTAC) on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) combined with F-18-FDG Positron Emission Tomography/Computed Tomography (PET/CT) metabolic imaging, compared with conventional SPECT MPI, remains to be fully elucidated. To evaluate the impact of CTAC on the accuracy of diagnosing viable myocardium using Tc-99m-MIBI dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT, compared to conventional SPECT MPI. 193 patients underwent CZT SPECT and F-18-FDG PET/CT imaging, while 39 patients underwent conventional SPECT and F-18-FDG PET/CT imaging, with both groups utilizing CT for attenuation correction. The injured myocardium (hibernating and scarring) was quantified using the Q.PET software. After CTAC, both groups showed significant improvements in perfusion of the injured myocardial areas, particularly in the inferior wall (INF). The reduction in perfusion was more notable in the CZT SPECT group than that in the conventional group, particularly in the inferior and lateral walls. Among patients with large cardiac chambers, those undergoing MPI with CZT, with normal weights, or males, hibernating myocardium (HM) and scar post-CTAC reductions were particularly significant in the INF. If HM ≥ 10% is considered an indicator for recommended revascularization, among the 87 patients without prior cardiac bypass, 25 (28.7%) might not require revascularization treatment. Dedicated cardiac CZT SPECT and conventional SPECT MPI combined with F-18-FDG PET/CT significantly influenced the assessment of viable myocardium. The impact of CTAC was more profound in dedicated cardiac CZT SPECT, particularly in the INF region. CTAC significantly enhances the accuracy of viable myocardial assessment and may influence clinical decisions regarding revascularization therapy. Therefore, CTAC should be routinely used in dedicated cardiac CZT SPECT MPI combined with F-18-FDG PET/CT for myocardial viability diagnosis.

Regional cerebral blood flow in behavioral variant of FTD: hypoperfusion patterns and clinical associations.

Findings from functional neuroimaging techniques, such as single-photon emission computed tomography (SPECT), may add useful evidence improving Frontotemporal Dementia (FTD) diagnosis. The aim of the present study was to investigate patterns of hypoperfusion in a group of patients diagnosed with the behavioral variant of FTD (bvFTD) and to explore the relationship between brain perfusion and clinical characteristics. Brain perfusion of 23 bvFTD patients was measured with SPECT scintigraphy in lobes and Brodmann areas (BAs) and the NeurogamTM software was used for image analysis. To assess behavioral disturbances and dementia severity, patients' informants completed the Frontotempotal Behavioral Inventory and the Frontotemporal Dementia Rating Scale. Descriptive statistics were used for the detection of pathological hypoperfusion in lobes and selected BAs. Associations among patients' clinical characteristics and perfusion in lobes were explored via non-parametric correlations. Participants presented pathological hypoperfusion in frontal, limbic and temporal lobes. The most prominent deficit was observed in limbic lobes, where all participants showed pathological hypoperfusion. Decreased perfusion was also observed in limbic, frontal and temporal BAs. Perfusion in the left and right frontal lobe was associated with behavioral disturbances and disease severity, which was also correlated with perfusion in right limbic, left and right temporal areas. Patterns of limbic, frontal and temporal hypopefusion were reported in the present study, along with associations between brain perfusion, behavioral disturbance and severity of dementia. Perfusion patterns can help to understand further associated brain biomarkers, contributing to early diagnosis and intervention in bvFTD.

Deep learning-based approach for acquisition time reduction in ventilation SPECT in patients after lung transplantation.

We aimed to evaluate the image quality and diagnostic performance of chronic lung allograft dysfunction (CLAD) with lung ventilation single-photon emission computed tomography (SPECT) images acquired briefly using a convolutional neural network (CNN) in patients after lung transplantation and to explore the feasibility of short acquisition times. We retrospectively identified 93 consecutive lung-transplant recipients who underwent ventilation SPECT/computed tomography (CT). We employed a CNN to distinguish the images acquired in full time from those acquired in a short time. The image quality was evaluated using the structural similarity index (SSIM) loss and normalized mean square error (NMSE). The correlation between functional volume/morphological volume (F/M) ratios of full-time SPECT images and predicted SPECT images was evaluated. Differences in the F/M ratio were evaluated using Bland-Altman plots, and the diagnostic performance was compared using the area under the curve (AUC). The learning curve, obtained using MSE, converged within 100 epochs. The NMSE was significantly lower (P < 0.001) and the SSIM was significantly higher (P < 0.001) for the CNN-predicted SPECT images compared to the short-time SPECT images. The F/M ratio of full-time SPECT images and predicted SPECT images showed a significant correlation (r = 0.955, P < 0.0001). The Bland-Altman plot revealed a bias of -7.90% in the F/M ratio. The AUC values were 0.942 for full-time SPECT images, 0.934 for predicted SPECT images and 0.872 for short-time SPECT images. Our findings suggest that a deep-learning-based approach can significantly curtail the acquisition time of ventilation SPECT, while preserving the image quality and diagnostic accuracy for CLAD.

High-contrast Compton camera: Challenges to high-quality and broadband imaging

In the field of nuclear medicine, various radiopharmaceuticals require wideband x-ray/gamma-ray imaging devices for clinical and treatment monitoring. Compton cameras, which perform imaging using high-energy gamma rays, have the potential to significantly increase the variety of radioactive nuclides that can be imaged. However, artifacts caused by the so-called “Compton cone” have hindered their clinical use. Therefore, we propose the use of a collimator to improve the contrast of images obtained using Compton cameras. In this study, we developed a high-contrast Compton camera by attaching a tungsten collimator to its front surface. The contrast is improved by applying weighting to the signals based on the distance that the high-energy gamma rays penetrated the collimator walls. As a demonstration, we visualized 198Au plates that emit 412-keV gamma rays with and without the collimator. In addition, low-energy (&amp;lt;200 keV) x-ray/gamma-ray imaging, which is difficult for conventional Compton cameras, was achieved by performing single-photon emission computed tomography (SPECT) using the collimator and scatterer of the Compton camera. We demonstrated broadband gamma-ray imaging by visualizing a 133Ba standard source using 81-keV and 356-keV gamma rays based on the principles of SPECT and Compton cameras, respectively.

Visualization of “subclinical consequence” after successful and uneventful surgical intervention for unruptured cerebral aneurysms

There are many studies on post-operative cognitive function after surgical clipping (SC) and endovascular coiling (EC) for unruptured cerebral aneurysms, but few reports focusing on possible subclinical damage. The aim of the present study was to detect the subclinical damage after surgical intervention. Patients with anterior circulation aneurysms who underwent either SC (SC group) or EC (EC group) were recruited. Imaging studies and evaluation of cognitive function were performed within 1 month preoperatively and at 6 months and 2 years postoperatively. The ipsilateral/contralateral cerebral blood flow (CBF) ratio (I/C ratio) calculated from values in four regions of interest (ROIs) placed on N-isopropyl-p-[123I] iodoamphetamine (123I-IMP)-single photon emission computed tomography (SPECT) was used to detect "subclinical consequence". "Subclinical consequence" was defined as post-operative CBF reduction without abnormality in other radiological examinations and cognitive tests. There were 14 patients in the SC group (mean age, 60.6±11.7 years) and 33 patients in the EC group (mean age, 67.5±7.2 years). All cognitive assessment results showed no significant reduction through the survey period. However, I/C ratios were restored by 2 years in the EC group not but in the SC group. I/C ratios at 6 months and 2 years were significantly lower in the SC group than the EC group (P<0.01). 123IMP-SPECT revealed a statistically significant reduction in ipsilateral CBF in patients who had an uneventful clinical course and no cognitive problems. The subclinical consequence could persist for at least 2 years following SC, and was less pronounced following EC.

Medical Image Fusion for Multiple Diseases Features Enhancement

ABSTRACTThroughout the past 20 years, medical imaging has found extensive application in clinical diagnosis. Doctors may find it difficult to diagnose diseases using only one imaging modality. The main objective of multimodal medical image fusion (MMIF) is to improve both the accuracy and quality of clinical assessments by extracting structural and spectral information from source images. This study proposes a novel MMIF method to assist doctors and postoperations such as image segmentation, classification, and further surgical procedures. Initially, the intensity‐hue‐saturation (IHS) model is utilized to decompose the positron emission tomography (PET)/single photon emission computed tomography (SPECT) image, followed by a hue‐angle mapping method to discriminate high‐ and low‐activity regions in the PET images. Then, a proposed structure feature adjustment (SFA) mechanism is used as a fusion strategy for high‐ and low‐activity regions to obtain structural and anatomical details with minimum color distortion. In the second step, a new multi‐discriminator generative adversarial network (MDcGAN) approach is proposed for obtaining the final fused image. The qualitative and quantitative results demonstrate that the proposed method is superior to existing MMIF methods in preserving the structural, anatomical, and functional details of the PET/SPECT images. Through our assessment, involving visual analysis and subsequent verification using statistical metrics, it becomes evident that color changes contribute substantial visual information to the fusion of PET and MR images. The quantitative outcomes demonstrate that, in the majority of cases, the proposed algorithm consistently outperformed other methods. Yet, in a few instances, it achieved the second‐highest results. The validity of the proposed method was confirmed using diverse modalities, encompassing a total of 1012 image pairs.

Clinical development and proof of principle testing of new regenerative vascular endothelial growth factor-D therapy for refractory angina: rationale and design of the phase 2 ReGenHeart trial

BackgroundDespite tremendous therapeutic advancements, a significant proportion of coronary artery disease patients suffer from refractory angina pectoris, that is, quality-of-life-compromising angina that is non-manageable with established pharmacological and interventional treatment...

Sinogram-characteristic-informed network for efficient restoration of low-dose SPECT projection data.

Single Photon Emission Computed Tomography (SPECT) sinogram restoration for low-dose imaging is a critical challenge in medical imaging. Existing methods often overlook the characteristics of the sinograms, necessitating innovativeapproaches. In this study, we introduce the Sinogram-characteristic-informed network (SCI-Net) to address the restoration of low-dose SPECT sinograms. Our aim is to build and train a model based on the characteristics of sinograms, including continuity, periodicity, multi-scale properties of lines in sinograms, and others, to enhance the model's understanding of the restorationprocess. SCI-Net incorporates several novel mechanisms tailored to exploit the inherent characteristics of sinograms. We implement a channel attention module with a decay mechanism to leverage continuity across adjacent sinograms, while a position attention module captures global correlations within individual sinograms. Additionally, we propose a multi-stage progressive integration mechanism to balance local detail and overall structure. Multiple regularization terms, customized to sinogram image characteristics, are embedded into the loss function for modeltraining. The experimental evaluations are divided into two parts: simulation data evaluation and clinical evaluation. The simulation data evaluation is conducted on a dataset comprising ten organ types, generated by the SIMIND Monte Carlo program from extended cardiac-torso (XCAT) anatomical phantoms. The dataset includes a total of SPECT sinograms with low-dose as input data and normal-dose as ground truth, consisting of 3881 sinograms in the training dataset and 849 sinograms in the testing set. When comparing the restoration of low-dose sinograms to normal-dose references, SCI-Net effectively improves performance. Specifically, the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM) on sinograms increase from 15.72 to 34.66 ( 0.001) and 0.6297 to 0.9834 ( 0.001), respectively, and on reconstructed images, reconstructed by maximum likelihood-expectation maximization (ML-EM), the PSNR and the SSIM improve from 21.95 to 33.14 ( 0.001) and 0.9084 to 0.9866 ( 0.001), respectively. We compared SCI-Net with existing methods, including baseline models, traditional reconstruction algorithms, end-to-end methods, sinogram restoration methods, and image post-processing methods. The experimental results and visual examples demonstrate that SCI-Net surpasses these existing methods in SPECT sinogram restoration. The clinical evaluation is conducted on clinical data of low-dose SPECT sinograms for spleen, thyroid, skull, and bone. These SPECT projection data are obtained from Discovery NM/CT670 scans. We compare the reconstructed images from the SCI-Net restored sinograms, the reconstructed images from the original low-dose sinograms, and the reconstructed images using the built-in algorithm of the Discovery NM/CT670. The results show that our method effectively reduces the coefficient of variation (COV) in the regions of interest (ROI) of the reconstructed images, thereby enhancing the quality of the reconstructed images through SPECT sinogramrestoration. Our proposed SCI-Net exhibits promising performance in the restoration of low-dose SPECT projection data. In the SCI-Net, we have implemented three mechanisms based on distinct forms, which are advantageous for the model to more effectively leverage the characteristics of sinograms and achieve commendable restorationoutcomes.

Simulated resections and responsive neurostimulator placement can optimize postoperative seizure outcomes when guided by fast ripple networks.

In medication-resistant epilepsy, the goal of epilepsy surgery is to make a patient seizure free with a resection/ablation that is as small as possible to minimize morbidity. The standard of care in planning the margins of epilepsy surgery involves electroclinical delineation of the seizure-onset zone and incorporation of neuroimaging findings from MRI, PET, single-photon emission CT and magnetoencephalography modalities. Resecting cortical tissue generating high-frequency oscillations has been investigated as a more efficacious alternative to targeting the seizure-onset zone. In this study, we used a support vector machine (SVM), with four distinct fast ripple (FR: 350-600 Hz on oscillations, 200-600 Hz on spikes) metrics as factors. These metrics included the FR resection ratio, a spatial FR network measure and two temporal FR network measures. The SVM was trained by the value of these four factors with respect to the actual resection boundaries and actual seizure-free labels of 18 patients with medically refractory focal epilepsy. Leave-one-out cross-validation of the trained SVM in this training set had an accuracy of 0.78. We next used a simulated iterative virtual resection targeting the FR sites that were of highest rate and showed most temporal autonomy. The trained SVM utilized the four virtual FR metrics to predict virtual seizure freedom. In all but one of the nine patients who were seizure free after surgery, we found that the virtual resections sufficient for virtual seizure freedom were larger in volume (P < 0.05). In nine patients who were not seizure free, a larger virtual resection made five virtually seizure free. We also examined 10 medically refractory focal epilepsy patients implanted with the responsive neurostimulator system and virtually targeted the responsive neurostimulator system stimulation contacts proximal to sites generating FR at highest rates to determine if the simulated value of the stimulated seizure-onset zone and stimulated FR metrics would trend towards those patients with a better seizure outcome. Our results suggest the following: (i) FR measures can accurately predict whether a resection, defined by the standard of care, will result in seizure freedom; (ii) utilizing FR alone for planning an efficacious surgery can be associated with larger resections; (iii) when FR metrics predict the standard-of-care resection will fail, amending the boundaries of the planned resection with certain FR-generating sites may improve outcome and (iv) more work is required to determine whether targeting responsive neurostimulator system stimulation contact proximal to FR generating sites will improve seizure outcome.

Utility of Quantitative Assessment of Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl Human Serum Albumin SPECT/CT in the Identification of Severe Liver Fibrosis: Its Complementary Diagnostic Value with Other Liver Function Indices.

To evaluate the value of Tc-99m-diethylenetriamine-penta-acetic acid-galactosyl human serum albumin (99mTc-GSA) single photon emission computed tomography (SPECT) for assessing liver fibrosis, and to assess its complementary value to other liver function indices such as fibrosis-4 (FIB-4) index and indocyanine green (ICG) clearance test parameters (ICG-R15 and ICG-K). Seventy-eight patients with chronic liver disease and hepatocellular carcinoma who underwent 99mTc-GSA scintigraphy and other liver function tests including ICG test and FIB-4 index prior to hepatectomy were studied. 99mTc-GSA imaging was performed with SPECT/CT scanner (Discovery NM/CT 670). Immediately after injection of 99mTc-GSA, dynamic imaging was performed for 20min, followed by SPECT data acquisition for 6min. LHL15 which is a conventional index by 99mTc-GSA planar images, and liver uptake ration (LUR) was measured from 99mTc-GSA SPECT images. From the liver resection specimens, the degree of liver fibrosis was graded according to the Ludwig scale (F0-4). Significant differences in LUR, LHL15, ICG-R15, ICG-K, platelet count and FIB-4 index were found between the F0-3 and F4 liver fibrosis patient groups (P < 0.05). Multivariate logistic regression analysis revealed that LUR and ICG-K were independent factors for identifying severe liver fibrosis (F4). Area under the curve of receiver operating curve analysis for the logistic regression model using LUR and ICG-K was 0.83. In the patient group with higher FIB-4 (≥ 3.16), the diagnostic performance of LUR for detecting severe liver fibrosis was significantly better than LHL15 (AUC: 0.83 vs. 0.75, P = 0.048). In the high FIB-4 index group, the sensitivity and specificity for identifying F4 was 88% and 85%, respectively, with LUR cutoff value of 41.2%. LUR, measured by 99mTc-GSA SPECT, is a useful indicator for identifying sever liver fibrosis. Particularly in patients with high FIB-4 index (≥ 3.16), LUR can be a valuable indicator to identify severe liver fibrosis with high diagnostic accuracy.

SPECT-MPI iterative denoising during the reconstruction process using a two-phase learned convolutional neural network

PurposeThe problem of image denoising in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a fundamental challenge. Although various image processing techniques have been presented, they may degrade the contrast of denoised images. The proposed idea in this study is to use a deep neural network as the denoising procedure during the iterative reconstruction process rather than the post-reconstruction phase. This method could decrease the background coefficient of variation (COV_bkg) of the final reconstructed image, which represents the amount of random noise, while improving the contrast-to-noise ratio (CNR).MethodsIn this study, a generative adversarial network is used, where its generator is trained by a two-phase approach. In the first phase, the network is trained by a confined image region around the heart in transverse view. The second phase improves the network’s generalization by tuning the network weights with the full image size as the input. The network was trained and tested by a dataset of 247 patients who underwent two immediate serially high- and low-noise SPECT-MPI.ResultsQuantitative results show that compared to post-reconstruction low pass filtering and post-reconstruction deep denoising methods, our proposed method can decline the COV_bkg of the images by up to 10.28% and 12.52% and enhance the CNR by up to 54.54% and 45.82%, respectively.ConclusionThe iterative deep denoising method outperforms 2D low-pass Gaussian filtering with an 8.4-mm FWHM and post-reconstruction deep denoising approaches.

The first experience of multi-modal in vivo PET/SPECT/CT and MRI imaging of laboratory mice with melanoma B16F10 (short message)

Background. For in vivo determination of size and metabolic characteristics of model tumors in laboratory animals, it is recommended to use imaging methods: positron emission tomography (PET), single-photon emission computed tomography (SPECT), computed tomography (CT) and magnetic resonance imaging (MRI). Due to the limited availability of hybrid scanners, it is necessary to investigate the feasibility of obtaining tomograms on separate devices with subsequent geometric comparison of images.Aim. To investigate the feasibility of multimodal imaging of mice with subcutaneous melanoma B16F10.Materials and methods. PET, SPECT and CT were performed using a preclinical VECTor 6 tomograph (MILabs, the Netherlands), MRI was performed using a preclinical nanoScan® 3T tomograph (Mediso, Hungary). The following modality combinations were studied: MRI and PET / CT with 18F-fluorodeoxyglucose; MRI and PET / CT with 18F-boronphenylalanine; MRI and PET / SPECT / CT with 18F-fluoroethyltyrosine (18F-FET) and 177lutetium – prostate-specific membrane antigen (177Lu-PSMA). Mice were immobilized in a custom-made device during scanning and during movement between tomographs. PET and MRI, SPECT and MRI images were fused in the program InterView FUSION 3.09.008.0000 through an intermediate stage of fusion with CT.Results. Multimodal PET / CT / MRI and PET / SPECT / CT / MRI images of tumor-bearing mice were obtained for the first time in Russia. PET / MRI data confirmed development of the tumor from 6 × 4 × 4 mm in size. PET / SPECT / CT / MRI enabled to image visceral organs with high accumulation of radionuclide tracers: pancreas with 18F-FET (standardized uptake value 2.6) and kidneys with 177Lu-PSMA (standardized uptake value 4.4), while the obtained images of organs did not merge and did not overlap.Conclusion. Multimodal imaging enables the selection of experimental animals with tumors of specific size and metabolic activity for the study of new radiopharmaceuticals, including those with vector delivery.

Radiosynthesis, Quality Control, and Small Animal Positron Emission Tomography Imaging of 68Ga-labelled Nano Molecules.

Small animal Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) imaging techniques are crucial in preclinical cancer research, necessitating meticulous attention to radiotracer synthesis, quality assurance, and in vivo injection protocols. This study presents a comprehensive workflow tailored to enhance the robustness and reproducibility of small animal PET experiments. The synthesis process in the radiochemistry laboratory using 68Ga is detailed, highlighting stringent quality control and assurance protocols for each radiotracer production. Parameters such as concentration, molar activity, pH, and purity are rigorously monitored, aligning with standards applicable to human studies. This methodology introduces streamlined syringe preparation and a custom-designed 30G cannula for precise intravenous injections into mice. Monitoring of animal health during scanning, including temperature and heart rate, ensures their well-being throughout the procedure. Dosages for PET and SPECT scans are predetermined to balance data acquisition with minimizing radiation exposure to animals and researchers. Similarly, CT scans employ pre-programmed settings to limit radiation exposure, especially pertinent in long-term studies assessing treatment effects. By optimizing these steps, the workflow aims to standardize procedures, reduce variability, and enhance the quality of small animal PET/SPECT/CT imaging. This resource provides valuable insights for researchers seeking to improve the accuracy and reliability of preclinical investigations in molecular imaging, ultimately advancing the field.

The possible connection between neutrophil-to-high-density lipoprotein ratio and cerebral perfusion in clinically established corticobasal syndrome: a pilot study.

Progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS) are tauopathic atypical parkinsonisms. Given their overlap in terms of clinical manifestation, there is growing interest in the mechanisms leading to these entities. In total, 71 patients were included in the study, 19 of whom were clinically diagnosed with CBS, 37 with PSP, and 15 with Parkinson's disease (PD). The mean ages of the participants were 72.8, 72.9, and 64.0 years, respectively, and the disease duration varied from 3 to 6 years. Each individual underwent blood collection. Morphological and biochemical evaluation of blood samples was performed to analyze the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and neutrophil-to-high-density lipoprotein ratio (NHR). A single-photon emission computed tomography (SPECT) with technetium-99m hexamethylpropyleneamine oxime (99Tc-HMPAO) tracer was used to assess perfusion in two regions of interest (ROI): the thalamus and insula. Using Pearson correlation to assess the linear relationship between NHR and perfusion in the insula and thalamus for CBS, PSP, and PD patients, the authors intended to verify possible correlations between NLR, PLR, and NHR and perfusion in the indicated ROIs. The study revealed a negative linear correlation between NHR and perfusion of both the left (Insula L; R = -0.59) and right (Insula R; R = -0.58) insula regions. Similar to the insula, a linear correlation between NHR and activity in both the left (Thalamus L) and right (Thalamus R) thalamus regions in CBS subjects with a relatively stronger correlation in the right thalamus (R = -0.64 vs. R = -0.58) was found. These observations were not confirmed in PSP and PD patients. Simultaneously using non-specific parameters for peripheral inflammation (NLR, PLR, and NHR) and perfusion, SPECT may be an interesting beginning point for further analysis of inflammatory disease mechanisms. To the best of our knowledge, this is the first study to address the potential correlation between the peripheral neuroinflammatory markers NLR, PLR, and NHR and perfusion disturbances in particular ROIs.