Single-photon Emission Computed Tomography Imaging Research Articles

Association of Long Noncoding RNA Expression Signatures with Stress-Induced Myocardial Perfusion Defects.

Stress-induced myocardial perfusion defects found in dipyridamole-thallium-201 single-photon emission computed tomography imaging may indicate vascular perfusion abnormalities and risk of obstructive or nonobstructive coronary heart disease. Besides nuclear imaging and subsequent coronary angiography (CAG), no blood test can indicate whether dysregulated homeostasis is associated with stress-induced myocardial perfusion defects. This study investigated the expression signature of long noncoding RNAs (lncRNAs) and genes involved in vascular inflammation and stress response in the blood of patients with stress-induced myocardial perfusion abnormalities (n = 27). The results revealed an expression signature consisting of the upregulation of RMRP (p < 0.01) and downregulations of THRIL (p < 0.01) and HIF1A (p < 0.01) among patients with a positive thallium stress test and no significant coronary artery stenosis within 6 months after baseline treatment. We developed a scoring system based on the expression signatures of RMRP, MIAT, NTT, MALAT1, HSPA1A, and NLRP3 to predict the need for further CAG among patients with moderate-to-significant stress-induced myocardial perfusion defects (area under the receiver operating characteristic curve = 0.963). Therefore, we identified a dysregulated expression profile of lncRNA-based genes in the blood that could be valuable for the early detection of vascular homeostasis imbalance and personalized therapy.

Differentiation between normal and abnormal kidneys using 99mTc-DMSA SPECT with deep learning in paediatric patients

To investigate the feasibility of using deep learning (DL) to differentiate normal from abnormal (or scarred) kidneys using technetium-99m dimercaptosuccinic acid (99mTc-DMSA) single-photon-emission computed tomography (SPECT) in paediatric patients. Three hundred and one 99mTc-DMSA renal SPECT examinations were reviewed retrospectively. The 301 patients were split randomly into 261, 20, and 20 for training, validation, and testing data, respectively. The DL model was trained using three-dimensional (3D) SPECT images, two-dimensional (2D) maximum intensity projections (MIPs), and 2.5-dimensional (2.5D) MIPs (i.e., transverse, sagittal, and coronal views). Each DL model was trained to determine renal SPECT images into either normal or abnormal. Consensus reading results by two nuclear medicine physicians served as the reference standard. The DL model trained by 2.5D MIPs outperformed that trained by either 3D SPECT images or 2D MIPs. The accuracy, sensitivity, and specificity of the 2.5D model for the differentiation between normal and abnormal kidneys were 92.5%, 90% and 95%, respectively. The experimental results suggest that DL has the potential to differentiate normal from abnormal kidneys in children using 99mTc-DMSA SPECT imaging.

Direct attenuation correction for 99mTc-3PRGD2 chest SPECT lung cancer images using deep learning.

The attenuation correction technique of single photon emission computed tomography (SPECT) images is essential for early diagnosis, therapeutic evaluation, and pharmacokinetic studies of lung cancer. 99mTc-3PRGD2 is a novel radiotracer for the early diagnosis and evaluation of treatment effects of lung cancer. This study preliminary discusses the deep learning method to directly correct the attenuation of 99mTc-3PRGD2 chest SPECT images. Retrospective analysis was performed on 53 patients with pathological diagnosis of lung cancer who received 99mTc-3PRGD2 chest SPECT/CT. All patients' SPECT/CT images were reconstructed with CT attenuation correction (CT-AC) and without attenuation correction (NAC). The CT-AC image was used as the reference standard (Ground Truth) to train the attenuation correction (DL-AC) SPECT image model using deep learning. A total of 48 of 53 cases were divided randomly into the training set, the remaining 5 were divided into the testing set. Using 3D Unet neural network, the mean square error loss function (MSELoss) of 0.0001 was selected. A testing set is used to evaluate the model quality, using the SPECT image quality evaluation and quantitative analysis of lung lesions tumor-to-background (T/B). SPECT imaging quality metrics between DL-AC and CT-AC including mean absolute error (MAE), mean-square error (MSE), peak signal-to-noise ratio (PSNR), structural similarity (SSIM), normalized root mean square error (NRMSE), and normalized Mutual Information (NMI) of the testing set are 2.62 ± 0.45, 58.5 ± 14.85, 45.67 ± 2.80, 0.82 ± 0.02, 0.07 ± 0.04, and 1.58 ± 0.06, respectively. These results indicate PSNR > 42, SSIM > 0.8, and NRMSE < 0.11. Lung lesions T/B (maximum) of CT-AC and DL-AC groups are 4.36 ± 3.52 and 4.33 ± 3.09, respectively (p = 0.81). There are no significant differences between two attenuation correction methods. Our preliminary research results indicate that using the DL-AC method to directly correct 99mTc-3PRGD2 chest SPECT images is highly accurate and feasible for SPECT without configuration with CT or treatment effect evaluation using multiple SPECT/CT scans.

Ultrafast cadmium-zinc-telluride-based renal single-photon emission computed tomography: clinical validation

BackgroundOne of the main limitations of 99mtechnetium-dimercaptosuccinic acid (DMSA) scan is the long acquisition time.ObjectiveTo evaluate the feasibility of short DMSA scan acquisition times using a cadmium-zinc-telluride-based single-photon emission computed tomography (SPECT) system in children.Materials and methodsThe data of 27 children (median age: 4 years; 16 girls) who underwent DMSA SPECT were retrospectively analyzed. Both planar and SPECT DMSA were performed. SPECT images were analyzed using coronal-simulated planar two-dimensional images. A reduction in SPECT acquisition time was simulated to provide 4 series (SPECT-15 min, SPECT-10 min, SPECT-5 min and SPECT-2.5 min). A direct comparison of the planar and SPECT series was performed, including semi-quantification reproducibility, image quality (mean quality score on a scale of 0 to 2) and inter- and intra-observer reproducibility of the scintigraphic patterns.ResultsThe overall image quality score (± standard deviation) was 1.3 (± 0.6) for the planar data set, 1.6 (± 0.5) for the SPECT-15 min data set, 1.4 (± 0.5) for the SPECT-10 min data set, 1.0 (± 0.5) for the SPECT-5 min data set and 0.6 (± 0.6) for the SPECT-2.5 min data set. Median Kappa coefficients for inter-observer agreement between planar and SPECT images were greater than 0.83 for all series and all readers except one reader for the SPECT-2.5 min series (median Kappa coefficient = 0.77).ConclusionShortening SPECT acquisitions to 5 min is feasible with minimal impact on images in terms of quality and reproducibility.Graphical

Effects of Polyethylene Glycol and 8-Aminooctanoic Acid Linkers on Melanoma Uptake of [99mTc]Tc-Tricarbonyl-NOTA-Conjugated Lactam-Cyclized α-MSH Peptides.

The purpose of this study was to evaluate the effect of linkers on tumor targeting and biodistribution of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex {[99mTc]Tc(CO)3-1,4,7-triazacyclononane-1,4,7-triyl-triacetic acid-polyethylene glycol-Nle-c[Asp-His-d-Phe-Arg-Trp-Lys]-CONH2} and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex {[99mTc]Tc(CO)3-NOTA-8-aminooctanoic acid-Nle-CycMSHhex} on B16/F10 melanoma-bearing mice. NOTA-PEG2Nle-CycMSHhex and NOTA-AocNle-CycMSHhex were synthesized and radiolabeled with [99mTc]Tc via the {[99mTc]Tc(CO)3(OH2)3}+ intermediate. The biodistribution of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex was determined on B16/F10 melanoma-bearing C57 mice. The melanoma imaging property of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was determined on B16/F10 melanoma-bearing C57 mice. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex and [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex were readily prepared with more than 90% radiochemical yields and exhibited MC1R-specific binding on B16/F10 melanoma cells. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex exhibited a higher tumor uptake than [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex at 2, 4, and 24 h postinjection. The tumor uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was 13.63 ± 1.13, 31.93 ± 2.57, 20.31 ± 3.23, and 1.33 ± 0.15% ID/g at 0.5, 2, 4, and 24 h postinjection, respectively. The tumor uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was 1.6 and 3.4 times the tumor uptake of [99mTc]Tc(CO)3-NOTA-AocNle-CycMSHhex at 2 and 4 h postinjection, respectively. Meanwhile, the normal organ uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was lower than 1.8% ID/g at 2 h postinjection. The renal uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex was only 1.73 ± 0.37, 0.73 ± 0.14, and 0.03 ± 0.01% ID/g at 2, 4, and 24 h postinjection, respectively. [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex showed high tumor to normal organ uptake ratios at 2 h postinjection. Single-photon emission computed tomography imaging revealed that the B16/F10 melanoma lesions could be clearly visualized by [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex at 2 h postinjection. Overall, the high tumor uptake and low kidney uptake of [99mTc]Tc(CO)3-NOTA-PEG2Nle-CycMSHhex highlighted its potential for melanoma imaging and warranted the future evaluation of [188Re]Re(CO)3-NOTA-PEG2Nle-CycMSHhex for melanoma therapy.

Triple modality image reconstruction of PET data using SPECT, PET, CT information increases lesion uptake in images of patients treated with radioembolization with ^{90}Y micro-spheres

PurposeNuclear medicine imaging modalities like computed tomography (CT), single photon emission CT (SPECT) and positron emission tomography (PET) are employed in the field of theranostics to estimate and plan the dose delivered to tumors and the surrounding tissues and to monitor the effect of the therapy. However, therapeutic radionuclides often provide poor images, which translate to inaccurate treatment planning and inadequate monitoring images. Multimodality information can be exploited in the reconstruction to enhance image quality. Triple modality PET/SPECT/CT scanners are particularly useful in this context due to the easier registration process between images. In this study, we propose to include PET, SPECT and CT information in the reconstruction of PET data. The method is applied to Yttrium-90 (^{90}Y) data.MethodsData from a NEMA phantom filled with ^{90}Y were used for validation. PET, SPECT and CT data from 10 patients treated with Selective Internal Radiation Therapy (SIRT) were used. Different combinations of prior images using the Hybrid kernelized expectation maximization were investigated in terms of VOI activity and noise suppression.ResultsOur results show that triple modality PET reconstruction provides significantly higher uptake when compared to the method used as standard in the hospital and OSEM. In particular, using CT-guided SPECT images, as guiding information in the PET reconstruction significantly increases uptake quantification on tumoral lesions.ConclusionThis work proposes the first triple modality reconstruction method and demonstrates up to 69% lesion uptake increase over standard methods with SIRT ^{90}Y patient data. Promising results are expected for other radionuclide combination used in theranostic applications using PET and SPECT.

UEFSD: Unsupervised medical images fusion based on exclusive features and saliency detection for SPECT-MRI images of glioma

Background and ObjectiveTo address the key feature extraction problem in glioma image fusion due to blurred edge and texture features, with certain exclusive features entangled with noise, we propose an unsupervised fusion network based on exclusive feature unentanglement and saliency detection (UEFSD). Single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) are taken as examples. MethodsFirst, the SPECT image in RGB space is converted to YCbCr space. Then, Y-channel SPECT and MRI images are fed into the UEFSD-based network and the attribute and object encoders are respectively used to separate the attribute vector of exclusive information for each modality and object feature mapping based on this attribute vector. Subsequently, the attribute vector and object feature maps are fused through the fusion decoder to obtain the fused image. In the training phase, first, the image is reconstructed using the attribute vector and object feature maps of the other modalities. The feature displaying the largest difference between the source and reconstructed images is identified as the exclusive feature that cannot be obtained via reconstruction. We trained the encoders and decoders in an unsupervised manner using exclusive feature loss as a high-level constraint and introducing a saliency mask as a low-level constraint. The trained attribute encoders and object encoders feed information to the fusion decoder to generate fused images. ResultUEFSD-based network was trained on Harvard Medical School's public dataset and tested by fusing MRI-T2 glioma images with their SPECT-T1 and SPECT-Tc counterparts. The experimental results demonstrate that UEFSD performs optimally in both subjective and objective indices when compared with nine other existing networks. ConclusionThe proposed UEFSD-based network can obtain clear edge and texture glioma features, which can effectively improve the rich and natural colour information of medical images and has the potential for computer-aided diagnosis system application.

SPECT and PET in nonlesional epilepsy

AbstractBackgroundPositron emission tomography (PET) and single-photon emission computed tomography (SPECT) are applied in epilepsy mostly during presurgical assessment. Nonlesional focal epilepsy is very challenging for presurgical evaluation in cases of refractory epilepsy.ObjectivesWe aimed to investigate the contribution of PET and SPECT to focus localization in nonlesional epilepsy.MethodsThe basic principles of SPECT and PET including different tracers were reviewed. The literature and the most recent publications are discussed in view of findings in nonlesional epilepsy.ResultsIctal SPECT shows a high sensitivity of over 80% for ictal onset zone in nonlesional epilepsy. Postprocessing with subtraction ictal SPECT co-registered with MRI (SISCOM) or statistical parametric mapping are the gold standard. Histopathological findings in nonlesional epilepsies with concordant ictal SPECT imaging show focal cortical dysplasia in up to 75% of cases. Ictal injection is unsuccessful in approximately 20% of cases and the procedure is very time consuming and labor intensive. Fluorodeoxyglucose (FDG)-PET in nonlesional epilepsy shows variable sensitivity of 46–76%. As with ictal SPECT, it benefits from postprocessing of co-registration with magnetic resonance imaging (MRI) or even statistical parametric mapping. Hybrid PET/magnetic resonance imaging (MRI) scanners provide additional benefits for identifying lesions. Other PET tracers (11C‑Flumazenil (FMZ), α-11C‑methyl-L-tryptophane (AMT)) are clinically applied in special cases only. Both procedures contribute complementary information in multimodal imaging diagnostics.ConclusionsIctal SPECT and PET are optional diagnostic tools for presurgical assessment in nonlesional epilepsies. They may reverse nonlesional to lesional epilepsy status and identify nonlesional epileptic foci with a fair chance of seizure freedom after epilepsy surgery.

Association of 99MTC- Hmpao Spect Measured Regional Cerebral Blood Flow And Serum Vitamin D Level With Clinical Staging of Parkinson’s Disease

Background: Parkinson’s disease (PD) is the most common neurodegenerative movement disorder. Diagnosis of PD can be made through Single-photon emission computed tomography (SPECT). Vitamin D deficiency has recently been proposed as a potential risk factor for PD. This study aimed to evaluate the association of 99mTc- HMPAO SPECT image findings and vitamin D status with clinical staging of PD. Methods: This cross-sectional study was conducted in Department of Neurology, Sir Salimullah Medical College Mitford Hospital for a period of 12 months. Total 66 diagnosed PD patients were included after taking informed written consent. Detailed demographic history and neurological examination were done. The severity of PD was assessed using the modified Hoehn and Yahr (H &amp; Y) scale. Serum 25-Hydroxyvitamin D level was measured for each participant. 99mTc- HMPAO SPECT imaging was done at Institute of Nuclear Medicine and Allied Sciences. Results: The mean age of the studied respondents was 71±8.72 (SD) years wherein maximum were male (59.1%) and aged above 70 years. The most common symptoms among the patients were tremor (78.8%) and bradykinesia (75.5%).The mean duration of PD was 5.74±2.22 (SD) years. Majority of the patients were diagnosed to have stage-2 (30.3%) followed by stage-2.5 (24.2%), stage-3 (16.7%), stage-4 (7.6%), stage-1 (4.5%), and stage-5 (3%). As the clinical stage of PD advanced from stages 1-5, the HMPAO uptake reduced significantly in the basal ganglia (p=0.006) .Vitamin-D level decreased significantly as the disease severity progress from stage-1 (27.8 ng/ml) to stage-5 (19.5 ng/ml) (p-value=0.008). Conclusion: Serum Vitamin-D level was inversely associated to severity of PD and decreased regional cerebral blood flow in basal ganglia in advanced stages of PD patients. However, further larger study is recommended. Bangladesh J Medicine 2023; 34(2): 112-120

A super-voxel-based method for generating surrogate lung ventilation images from CT.

Purpose: This study aimed to develop and evaluate , a super-voxel-based method for surrogate computed tomography ventilation imaging (CTVI). Methods and Materials: The study used four-dimensional CT (4DCT) and single-photon emission computed tomography (SPECT) images and corresponding lung masks from 21 patients with lung cancer obtained from the Ventilation And Medical Pulmonary Image Registration Evaluation dataset. The lung volume of the exhale CT for each patient was segmented into hundreds of super-voxels using the Simple Linear Iterative Clustering (SLIC) method. These super-voxel segments were applied to the CT and SPECT images to calculate the mean density values (D mean) and mean ventilation values (Vent mean), respectively. The final CT-derived ventilation images were generated by interpolation from the D mean values to yield . For the performance evaluation, the voxel- and region-wise differences between and SPECT were compared using Spearman's correlation and the Dice similarity coefficient index. Additionally, images were generated using two deformable image registration (DIR)-based methods, and , and compared with the SPECT images. Results: The correlation between the D mean and Vent mean of the super-voxel was 0.59 ± 0.09, representing a moderate-to-high correlation at the super-voxel level. In the voxel-wise evaluation, the method achieved a stronger average correlation (0.62 ± 0.10) with SPECT, which was significantly better than the correlations achieved with the (0.33 ± 0.14, p < 0.05) and (0.23 ± 0.11, p < 0.05) methods. For the region-wise evaluation, the Dice similarity coefficient of the high functional region for (0.63 ± 0.07) was significantly higher than the corresponding values for the (0.43 ± 0.08, p < 0.05) and (0.42 ± 0.05, p < 0.05) methods. Conclusion: The strong correlation between and SPECT demonstrates the potential usefulness of this novel method of ventilation estimation for surrogate ventilation imaging.

Radiolabelled folate micellar carriers as proposed diagnostic aid for CNS tumors by nasal route.

Glioma refers to the most atypical variant of the malignant central nervous system tumors posturing massive challenge to the research fraternity owing to the flimsy improvement in the patient survival rate over the past years. The aim of the proposed work was developing a diagnostic aid for brain tumors, which could be administered via the non-invasive intranasal route. Since overexpression of folate receptors in the central nervous system tumors is 500 times more than the normal healthy cells, we aimed at fabricating a radiolabeled folate encapsulated micellar delivery system to be given via the nasal route. Folate conjugated bifunctional chelating agent was synthesized, radiolabeled with 99mTc, and encapsulated in a micellar carrier. The fabricated micelles were further evaluated for in vivo nasal toxicity in rats and the same were found safe for intranasal administration. The fabricated micelles owing to their nano size, mucoadhesive nature, and enhanced permeation were observed to have a higher uptake into the brain (around 16% in 4 h) than as compared to the radiolabeled conjugated folate solution when studied for in vivo biodistribution in mice. Single-photon emission computerized tomography imaging performed in higher animals upon intranasal administration of the micellar formulation revealed enhanced uptake of the micelles into the animal brain. It is believed that the aforementioned formulation can be of a great diagnostic value in the detection of not only brain tumors but also other folate expressing cancers such as cervical, breast, and lungs as the system is fast, non-toxic, accurate, non-invasive, and simple.

State-of-the-art challenges and emerging technologies in radiation detection for nuclear medicine imaging: A review

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are established medical imaging modalities that have been implemented for decades, but improvements in detector design and camera electronics are needed for advancement of both imaging technologies. Detectors are arguably the most important aspect of the systems. Similar to SPECT, PET typically relies on indirect conversion of gamma radiation via scintillators coupled with photosensors used to convert optical photons produced by the scintillator into an electrical signal. PET detectors are defined by their energy resolution, timing resolution, and spatial resolution, all of which affect and determine the image quality. Improvements in energy resolution have been shown by increasing the brightness of the scintillator utilizing materials like cerium bromide (CeBr3) or switching to a direct conversion detector, such as cadmium zinc telluride (CZT) or thallium bromide (TlBr). Timing resolution for PET is a focal point of the current research. Improving the timing resolution improves the signal-to-noise of the PET system and is integral to the implementation of time-of-flight PET. By utilizing novel configurations, such as side readouts on scintillators, timing resolution has been improved dramatically. Similarly, metascintillators, which use complex combinations for the scintillator material, have also shown improvements to the timing resolution. Additional research has focused on using Cherenkov light emission in scintillators to further improve the timing resolution. Other research is focused on using convolutional neural networks and other signal processing to enhance timing resolution. Lastly, aside from acollinearity and positron range, spatial resolution is impacted by the PET detector, therefore improving the intrinsic spatial resolution of the detector will allow for smaller features to be imaged. One method for improving the spatial resolution is to use unique configurations with layered scintillators. Additionally, monolithic scintillators have also been shown to have reduced spatial resolution. The future for both SPECT and PET image system advancement will depend on continued development of the detectors via many different pathways including materials, signal processing, physics, and novel configurations. In this review article, we will discuss challenges and emerging technologies for state-of-the-art radiation detectors utilized in PET and SPECT.

Integration of advanced 3D SPECT modelling for pinhole collimators into the open-source STIR framework.

Single-photon emission computed tomography (SPECT) systems with pinhole collimators are becoming increasingly important in clinical and preclinical nuclear medicine investigations as they can provide a superior resolution-sensitivity trade-off compared to conventional parallel-hole and fanbeam collimators. Previously, open-source software did not exist for reconstructing tomographic images from pinhole-SPECT datasets. A 3D SPECT system matrix modelling library specific for pinhole collimators has recently been integrated into STIR, an open-source software package for tomographic image reconstruction. The pinhole-SPECT library enables corrections for attenuation and the spatially variant collimator-detector response by incorporating their effects into the system matrix. Attenuation correction can be calculated with a simple single line of response or a full model. The spatially variant collimator-detector response can be modelled with a point spread function and depth of interaction corrections for increased system matrix accuracy. In addition, improvements to computational speed and memory requirements can be made with image masking. This work demonstrates the flexibility and accuracy of STIR's support for pinhole-SPECT datasets using measured and simulated single-pinhole SPECT data from which reconstructed images were analysed quantitatively and qualitatively. The extension of the open-source STIR project with advanced pinhole-SPECT modelling will enable the research community to study the impact of pinhole collimators in several SPECT imaging scenarios and with different scanners.

Influence on voxel-based dosimetry: noise effect on absorbed dose dosimetry at single time-point versus sequential single-photon emission computed tomography.

The purpose of this study was to evaluate how statistical fluctuation in single-photon emission computed tomography (SPECT) images propagate to absorbed dose maps. SPECT/computed tomography (CT) images of iodine-131 filled phantoms, using different acquisition and processing protocols, were evaluated using STRATOS software to assess the absorbed dose distribution at the voxel level. Absorbed dose values and coefficient of variation (COV) were analyzed for dosimetry based on single time-point SPECT images and time-integrated activities of SPECT sequences with low and high counts. Considering dosimetry based on a single time-point, the mean absorbed dose was not significantly affected by total counts or reconstruction parameters, but the uniformity of the absorbed dose maps had an almost linear correlation with SPECT noise. When high- and low-count SPECT sequences were used to generate an absorbed dose map, the absorbed dose COV for each of the temporal sequences was slightly lower than the absorbed dose COV based on the single SPECT image with the highest count included in the sequence. The impact of changes in SPECT counts and reconstruction parameters is almost linear when dosimetry is based on isolated SPECT images, but less pronounced when dosimetry is based on sequential SPECTs.

Development and task-based evaluation of a scatter-window projection and deep learning-based transmission-less attenuation compensation method for myocardial perfusion SPECT.

Attenuation compensation (AC) is beneficial for visual interpretation tasks in single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). However, traditional AC methods require the availability of a transmission scan, most often a CT scan. This approach has the disadvantage of increased radiation dose, increased scanner costs, and the possibility of inaccurate diagnosis in cases of misregistration between the SPECT and CT images. Further, many SPECT systems do not include a CT component. To address these issues, we developed a Scatter-window projection and deep Learning-based AC (SLAC) method to perform AC without a separate transmission scan. To investigate the clinical efficacy of this method, we then objectively evaluated the performance of this method on the clinical task of detecting perfusion defects on MPI in a retrospective study with anonymized clinical SPECT/CT stress MPI images. The proposed method was compared with CT-based AC (CTAC) and no-AC (NAC) methods. Our results showed that the SLAC method yielded an almost overlapping receiver operating characteristic (ROC) plot and a similar area under the ROC (AUC) to the CTAC method on this task. These results demonstrate the capability of the SLAC method for transmission-less AC in SPECT and motivate further clinical evaluation.

Safety, biodistribution and radiation dosimetry of [123I]ioflupane in healthy Chinese volunteers

Background[123I]ioflupane is a radiopharmaceutical used to visualise the dopaminergic neuron terminals in the striata, to aid in the differential diagnosis among Parkinsonian syndromes (e.g., Parkinson’s disease). However, nearly all of the subjects in the initial development studies of [123I]ioflupane were Caucasian.Methods8 Chinese healthy volunteers (HVs) received a single 111 MBq ± 10% dose of [123I]ioflupane and had simultaneous whole-body (head to mid-thigh) anterior and posterior planar scintigraphy scans at 10 min and 1, 2, 4, 5, 24, and 48 h. To estimate biodistribution, dosimetry was evaluated for the Cristy–Eckerman female and hermaphrodite male phantoms. Single-photon emission computed tomography (SPECT) images of the brain were acquired at 3 and 6 h after injection. Blood samples and all voided urine were collected for 48 h for pharmacokinetic analysis. The results were then compared with those of a similar European study.ResultsThere were strong similarities in uptake and biodistribution between the Chinese and European studies. Excretion was primarily renal, and the values were similar for the first 5 h but diverged after that, possibly because of differences in subjects’ height and weight. Tracer uptake in regions of interest in the brain was stable over the imaging window of 3 to 6 h. The difference in mean effective dose for Chinese HVs vs European HVs (0.028 ± 0.00448 vs 0.023 ± 0.00152 mSv/MBq) was not clinically significant. The [123I]ioflupane was well tolerated.ConclusionThis study demonstrated that a single 111 MBq ± 10% dose of [123I]ioflupane injection was safe and well tolerated, and the SPECT imaging window of 3 to 6 h after injection of [123I]ioflupane was appropriate in Chinese subjects.Trial registration number ClinicalTrials.gov: NCT04564092.

Aluminum Fluoride-18 Labeled Mannosylated Dextran: Radiosynthesis and Initial Preclinical Positron Emission Tomography Studies

PurposeIn addition to being expressed on liver sinusoidal endothelial cells, mannose receptors are also found on antigen-presenting cells, including macrophages, which are mainly involved in the inflammation process. Dextran derivatives of various sizes containing cysteine and mannose moieties have previously been labeled with 99mTc and used for single-photon emission computed tomography imaging of sentinel lymph nodes. In this study, we radiolabeled 21.3-kDa D10CM with positron-emitting 18F for initial positron emission tomography (PET) studies in rats.ProceduresD10CM was conjugated with 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) chelator and radiolabeled with the aluminum fluoride-18 method. The whole-body distribution kinetics and stability of the intravenously administered tracer were studied in healthy male Sprague-Dawley rats by in vivo PET/CT imaging, ex vivo gamma counting, and high-performance liquid chromatography analysis.ResultsAl[18F]F-NOTA-D10CM was obtained with a radiochemical purity of >99% and molar activity of 9.9 GBq/μmol. At 60 minutes after injection, an average of 84% of the intact tracer was found in the blood, indicating excellent in vivo stability. The highest radioactivity concentration was seen in the liver, spleen, and bone marrow, in which mannose receptors are highly expressed under physiological conditions. The uptake specificity was confirmed with in vivo blocking experiments.ConclusionsOur results imply that Al[18F]F-NOTA-D10CM is a suitable tracer for PET imaging. Further studies in disease models with mannose receptor CD206-positive macrophages are warranted to clarify the tracer’s potential for imaging of inflammation.Graphical abstract

178 Adjunctive Use of Preoperative SPECT Imaging for Evaluation of Chronic Cervical and Lumbar Pain

INTRODUCTION: Radionuclide bone scintigraphy with single photon emission computed tomography (SPECT) has been used to evaluate foci of inflammation within the spinal axis. Studies have reported its use as an tool for recognition of pain foci and spondolytic change. As an adjunctive test SPECT may prove to give valuable insight into areas of focal inflammation within the spinal axis and therefore serve as a tool for guiding operative and nonoperative intervention in patients with degenerative spine disease. METHODS: We performed a retrospective case series to identify patients with chronic neck/back pain who underwent SPECT imaging for pre-operative evaluation. Patient demographics, area of uptake, correlation with pain morphology, type of intervention, and degree of symptom resolution were quantified. Patients were excluded if they had prior surgery/intervention at the level corresponding to symptomatology. RESULTS: Thirty-two patients underwent SPECT imaging. Patients presented with axial back pain (97%) and radicular pain (42%). Radiotracer uptake was seen in facet and/or disc space at the level of symptomology in 44% of patients, facet alone (22%), disc space alone (22%), and uncovertebral joint (12%). Interventions included facet injections (26 patients), basovertebral plexus ablation (7 patients), and open/minimally-invasive surgery (9 patients). Two patients underwent anterior cervical discectomy and the remainder of our cohort underwent lumbar instrumentation and fusion. All but one surgical patient (97%) reported significant relief of symptoms. CONCLUSIONS: SPECT imaging may be useful adjunctive imaging modality to evaluate for focal areas of inflammation not readily observed on MRI or CT. Our experience suggests that SPECT can identify areas of pathology that responsive to various types of intervention.

Preliminary study of integrated C-arm CT/SPECT imaging system for online adaptive 3D brachytherapy using Monte Carlo simulation

Recent advancements in high-dose-rate brachytherapy have led to remarkable clinical outcomes. However, these new developments can cause unknown uncertainties with respect to actual dose delivery, which are yet to be clarified. Therefore, an accurate dose verification system is required. Currently, procedures for image-guided adaptive brachytherapy are constrained by the following limitations: (1) patient transportation between the treatment room and CT/MR (computerized tomography/magnetic resonance) imaging room can displace the application position, (2) the physiological and anatomical changes in the patient’s body cannot be observed during the treatment schedule involving 3–10 fraction, and (3) the movement of the radioactive source inside the body is impossible to track. This study proposes a concept of an integrated online imaging system, which is based on integrated CT and single-photon emission computed tomography (SPECT), namely, the C-arm CT/SPECT system—a combination of a C-arm fluoroscopic x-ray imaging system and an attachable parallel-hole collimator over the imaging detector. The Geant4 software is used to simulate the application of the C-arm CT/SPECT system for 192Ir-based brachytherapy in a pelvis-like phantom. To improve the image quality of C-arm CT/SPECT acquired with limited-angle information, we utilized an adaptive-steepest-descent-projection-onto-convex-sets framework that incorporates additional prior information for the proposed system. Furthermore, we confirmed that SPECT images can be obtained using a parallel-hole collimator and estimated the dose distribution in the medium and CT/SPECT fusion imaging during treatment. This strategy is expected to be effectively implemented in online image-guided adaptive brachytherapy and patient-dose verification.

ASSESSMENT OF RISK FACTORS BETWEEN PREMENOPAUSALAND POSTMENOPAUSAL WOMEN PRESENTING WITH ACUTE MYOCARDIAL INFARCTION TO TERTIARY CARE HOSPITAL IN KAKINADA: A CASE CONTROL STUDY

Background: Acute myocardial infarction is a major public health problem in both in developing and developed countries despite impressive strides in the diagnosis and management. Effect of hormone replacement therapy in post-menopausal women is uncertain. Some observational studies suggest that estrogen replacement protects against the incidence of coronary artery disease. Prospective control trials have not yet conrmed the benecial effect of hormone replacement therapy. Hormone replacement therapy shows no benecial effect in reducing the morbidity and mortality both in western and Indian studies. Materials and Methods: This is a case control study conducted by the Department of cardiology, Government General Hospital (tertiary care hospital) Kakinada District, Andhra Pradesh. 200 female patients of Acute Myocardial Infarction were included in the study conducted between December 2021 to November 2022. Results: The mean (Standard deviation) age of patients was 51.05 ± 5.92. peak age of incidence between 51-60 years 60%. Out of 200, 68 were pre-menopausal and 132 were post-menopausal. In pre-menopausal group 77.9% had Unstable Angina, 14.7% with Non ST elevation MI and 7.4% with ST Elevation MI. In post-menopausal group, 27.3% had STEMI, 21.2% had NSTEMI and 51.5% had Unstable Angina. 27.9% in pre-menopausal group and 42.4% in post-menopausal group were having dyslipidemia. Conclusions: Identication of co-morbidities and risk factors of CAD in women will lead us to the correct diagnosis and early appropriate management. Noninvasive tests such as stress echocardiography and perfusion testing with cardiac magnetic resonance or single-photon emission computed tomography imaging should be used in identifying patients at risk, followed by further risk stratication by appropriate invasive testing such as CAG