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Performance of whole-body 18F-FDG PET/CT as a posttreatment surveillance tool for sinonasal malignancies
摘要： Purpose To determine the diagnostic utility of posttreatment surveillance whole-body 18F-FDG PET/CT in detecting local tumor recurrence (R), regional lymph-node metastasis (LM), and distant metastasis (DM) in asymptomatic sinonasal cancer patients. Methods Eighty consecutive patients (53 men, 27 women; mean age, 60 years; range, 28–92 years) who had undergone 197 posttreatment whole-body 18F-FDG PET/CT examinations for sinonasal malignancies between January 2009 and August 2017 were retrospectively reviewed. 18F-FDG PET/CT findings were categorized as positive or negative for R, LM, and DM, separately. Outcomes of 18F-FDG PET/CT scans were compared with the final diagnosis confirmed by histological analysis or follow-up period for a minimum 12 months. The diagnostic accuracy of scans was calculated for each site using contingency tables. Impact on the management of 18F-FDG PET/CT examinations was additionally evaluated. Results 18F-FDG PET/CT scans identified 37/44 of local recurrences, 21/23 of LMs, and 30/37 of DMs. For local recurrence, sensitivity, specificity, positive predictive value, and negative predictive value were 84% (68–97%), 95% (80–100%), 84% (68–97%), and 95% (80–100%), respectively. For LM, the respective values were 91% (75–100%), 99% (83–100%), 91% (75–100%), and 99% (83–100%). For DM, the values were 81% (64–97%), 99% (85–100%), 97% (81–100%), and 96% (81–100%), respectively. 18F-FDG PET/CT accounted for a change in management of 85% patients with recurrences. Conclusions Whole-body 18F-FDG PET/CT is a suitable surveillance tool for sinonasal malignancies in detecting locoregional and distant recurrences in asymptomatic patients without any evidence of recurrence on regular follow-up and endoscopy during the posttreatment period.
关键词： Posttreatment,Recurrence,Surveillance,Sinonasal malignancies,18F-FDG PET/CT
更新于2025-09-23 15:23:52
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A feasibility study of the time reversal violation test based on polarization of annihilation photons from the decay of ortho-Positronium with the J-PET detector
摘要： The Jagiellonian Positron Emission Tomograph (J-PET) is a novel device being developed at Jagiellonian University in Krakow, Poland based on organic scintillators. J-PET is an axially symmetric and high acceptance scanner that can be used as a multi-purpose detector system. It is well suited to pursue tests of discrete symmetries in decays of positronium in addition to medical imaging. J-PET enables the measurement of both momenta and the polarization vectors of annihilation photons. The latter is a unique feature of the J-PET detector which allows the study of time reversal symmetry violation operator which can be constructed solely from the annihilation photons momenta before and after the scattering in the detector.
关键词： Time reversal symmetry,Momenta,Polarization,Annihilation photons,J-PET detector,Discrete symmetries,Ortho-positronium
更新于2025-09-23 15:23:52
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Axial Fourier Rebinning for Time-of-Flight PET
摘要： Fully 3D time-of-flight (TOF) PET scanners offer the potential of substantially improved image quality in clinical PET imaging. The main challenges of 3D TOF PET imaging are the data storage with either list-mode or binned formats, and the reconstruction time using iterative algorithms. Previously, we derived the Fourier rebinning and consistency equations (FORCEs), and showed 3D TOF data can be fully characterized by two consistency equations. In this work, we present an exact Fourier rebinning for 3D TOF data based on the axial consistency equation to dramatically reduce the data storage and the reconstruction time. Starting from pre-corrected 3D TOF data, the axial Fourier rebinning algorithm estimates a 2D TOF sinogram for each transverse slice without information loss. Since the 3D TOF data are axially truncated, we provide a solution to estimate the missing portion in the oblique TOF projection data. The proposed axial Fourier rebinning for TOF data (axFRT) can take advantage of all the 3D TOF data statistics, and the rebinned 2D TOF data can then be reconstructed using any algorithms for 2D or 2.5D TOF reconstructions. The axFRT algorithm allows the axial data sets being rebinned independently, and there are tens of thousands of such data sets which can naturally take advantage of the massively parallel processors to dramatically speedup the rebinning. We show numerical simulations to demonstrate that axFRT produces accurate and unbiased rebinned sinograms even for TOF PET with large axial acceptance angle. The axFRT will be particularly useful for 3D TOF PET with large axial field of view for PET imaging applications including dynamic, whole- or total-body imaging.
关键词： image reconstruction,positron emission tomography (PET),time-of-flight,Axial Fourier rebinning
更新于2025-09-23 15:23:52
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Uso de análisis semicuantitativo en la recidiva local del carcinoma colorrectal mediante PET/TC con 18F-FDG: ?mito o realidad?
摘要： Objective: Recurrence of colorectal cancer is mostly seen within the first 2 years after surgery. The most frequent site of recurrence is the postsurgical areas and its surroundings. The purpose of this study was to evaluate the usefulness of semiquantitative analysis of 18Fluorine fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in determining recurrence of colorectal carcinoma in the operation site. Material and methods: Files of 35 patients with colorectal carcinoma (25 men, 10 women, mean age: 59.25 ± 2.82 years, range: 27-80 years) who were treated with surgery and underwent FDG PET/CT scanning for restaging of colorectal carcinoma and showing increased FDG uptake in the postsurgical area, were retrospectively analysed. Besides calculating SUVmax of the areas showing FDG uptake, SUVmax of physiological colonic activity was also obtained and SUVmax of lesion/SUVmax of colonic wall (RSUVmax), was calculated. Characteristics of FDG uptake were classified according to histological analysis or clinical and imaging follow-up. Results: In 17 of 35 patients (49%) the standard of reference for the final diagnosis was histologic analysis and in 18 (51%), final diagnosis was based on imaging and clinical follow-up. In 15 of 35 patients (43%) the etiology of increased FDG uptake was recurrence and in 20 (57%), FDG accumulation was observed due to benign etiology. The difference between the mean of the results of SUVmax in patients with recurrent disease and with no evidence of recurrence was statistically significant (P = .030). For SUVmax, a cut-off value for recurrence was calculated as 9.51 with a sensitivity of 80% and a specificity of 70%. In terms of RSUVmax results, a statistically significant difference was also observed between mean values in patients with recurrent disease and in those without (P = .002). ROC analysis demonstrated that the best predictive value of RSUVmax for recurrence was 1.75 with a sensitivity of 67% and specificity of 95%. Conclusions: Semiquantitative analysis of FDG PET/CT may be used in detecting recurrent disease of patients with colorectal carcinoma. Eliminating interfering physiological colonic activity in analysis may have an incremental effect on the success of this technique, by means of increasing the specificity.
关键词： Colorectal carcinoma,Physiological activity,Recurrence,Semiquantitative,FDG PET/CT
更新于2025-09-23 15:23:52
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Image-based Absorbed Dosimetry of Radioisotope
摘要： An absorbed dose calculation method using a digital phantom is implemented in normal organs. This method cannot be employed for calculating the absorbed dose of tumor. In this study, we measure the S-value for calculating the absorbed dose of each organ and tumor. We inject a radioisotope into a torso phantom and perform Monte Carlo simulation based on the CT data. The torso phantom has lung, liver, spinal, cylinder, and tumor simulated using a spherical phantom. The radioactivity of the actual absorbed dose is measured using the injected dose of the radioisotope, which is Cu-64 73.85 MBq, and detected using a glass dosimeter in the torso phantom. To perform the Monte Carlo simulation, the information on each organ and tumor acquired using the PET/CT and CT data provides anatomical information. The anatomical information is offered above mean value and manually segmented for each organ and tumor. The residence time of the radioisotope in each organ and tumor is calculated using the time activity curve of Cu-64 radioactivity. The S-values of each organ and tumor are calculated based on the Monte Carlo simulation data using the spatial coordinate, voxel size, and density information. The absorbed dose is evaluated using that obtained through the Monte Carlo simulation and the S-value and the residence time in each organ and tumor. The absorbed dose in liver, tumor1, and tumor2 is 4.52E-02, 4.61E-02, and 5.98E-02 mGy/MBq, respectively. The difference in the absorbed dose measured using the glass dosimeter and that obtained through the Monte Carlo simulation data is within 12.3%. The result of this study is that the absorbed dose obtained using an image can evaluate each difference region and size of a region of interest.
关键词： Absorbed dosimetry,Torso phantom,Cu-64,PET/CT,Glass dosimeter
更新于2025-09-23 15:23:52
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Clinical Value of Positron Emission Tomography-Computed Tomography Combined with Ultrasound in Detection of Primary Tumors in Patients with Malignant Ascites
摘要： Objective: To investigate and discuss the clinical value of positron emission tomography-computed tomography (PET-CT) combined with ultrasound in detection of primary tumors in patients with malignant ascites (MA). Materials and Methods: A total of 122 malignant tumor patients with ascites as the initial symptom and 48 patients with benign ascites were enrolled in this study. All patients underwent PET-CT and abdominal B-ultrasound examinations. The corresponding specificity, sensitivity, accuracy rate, positive predictive value, and negative predictive value of PET-CT, abdominal B-ultrasound, and combined detection group were recorded, respectively, with pathological findings as the gold standards. Statistical Product and Service Solutions 17.0 software was used for statistical analysis. p < 0.05 suggested that the difference was statistically significant. Results: The detection rate of primary foci through PET-CT was 79.5%, of which the detection rate of primary foci of MA derived from gastric cancer was the highest. The detection rate of primary foci through B-ultrasound was 62.5%, which is the highest for MA derived from ovarian cancer. B-ultrasound had the highest specificity in diagnosing the primary foci of MA (73.2%), PET-CT had the highest sensitivity in diagnosing the primary foci of MA (91.7%), and PET-CT combined with abdominal B-ultrasound had the highest sensitivity and accuracy in diagnosing the primary foci of MA (98.1% and 89.1%, respectively). The diagnostic accuracy rate of B-ultrasound was the highest in detecting tumors >5 cm (77.0%), whereas that of PET-CT was the highest in detecting tumors of 3–5 cm (84.2%). Conclusion: The PET-CT combined with ultrasound is conducive to improving the diagnostic efficiency for primary tumors in patients with MA.
关键词： ultrasound,malignant ascites,PET-CT,clinical value
更新于2025-09-23 15:23:52
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Design and performance evaluation of high resolution small animal PET scanner based on monolithic crystal: a simulation study
摘要： Dedicated small-animal PET scanners functionality can be optimized by improving the sensitivity and spatial resolution of the scanner. Approximately most of the developed and commercially available small-animal PET scanners are equipped with pixelated scintillators; therefore, their spatial resolution is limited to the crystal pixel size. Complex fabrication, low-sensitivity, and disability in depth of interaction calculation (DOI) are the major disadvantages of pixelated crystals. However, monolithic scintillator crystals are known as one of the most commonly used substitutions, as they have higher sensitivity, DOI recognition, and lower cost. We already designed and implemented a dedicated small-animal PET scanner based on pixelated scintillator crystals and silicon photomultiplier (SiPM). In this study, we plan to present a new optimized design based on the monolithic crystal, with similar performance by the previous scanner. Then we would optimize the thickness of the monolithic crystals for animal PET scanners as a function of sensitivity and spatial resolution. All simulations were performed based on GEANT4, a validated Monte Carlo toolkit. We simulated a recently fabricated scanner with pixelated crystals and compared it with a simulated scanner based on an optimized monolithic crystal. The experimental setup used for comparison and validation is a small Animal PET consisting of ten pixelated modules. This study anticipates that by replacing a pixelated crystal (consist of 24 × 24 LYSO elements, and 2 × 2 × 10 mm3 crystal size) with a monolithic crystal (with 8 mm thickness and 50.2 × 50.2 entrance area), the average spatial resolution stays the same and sensitivity grows ～ 17% in the center of AFOV and also the fabrication cost dives remarkably. Simulation reveals that although the depth of interaction DOI was not taken into consideration, the crystals with 6 mm thickness have acceptable spatial resolution (～ 1.3 mm FWHM at the centre of the AFOV) and relatively good absolute sensitivity (～ 1.6%).
关键词： SPECT,coronary CT angiography (CTA),PET PET/CT,Gamma camera,Models and simulations
更新于2025-09-23 15:22:29
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PET Imaging of the P2X7 Ion Channel with a Novel Tracer [18F]JNJ-64413739 in a Rat Model of Neuroinflammation
摘要： Purpose: The P2X7 receptor, an adenosine triphosphate (ATP)-gated purinoreceptor, has emerged as one of the key players in neuroinflammatory processes. Therefore, developing a positron emission tomography (PET) tracer for imaging of P2X7 receptors in vivo presents a promising approach to diagnose, monitor, and study neuroinflammation in a variety of brain disorders. To fulfill the goal of developing a P2X7 PET ligand as a biomarker of neuroinflammation, [18F]JNJ-64413739 has been recently disclosed. Procedures: We evaluated [18F]JNJ-64413739 in a rat model of neuroinflammation induced by an intracerebral injection of lipopolysaccharide (LPS). In vivo brain uptake was determined by PET imaging. Upregulation of neuroinflammatory biomarkers was determined by quantitative polymerase chain reaction (qPCR). Distribution of the tracer in the brain was determined by ex vivo autoradiography (ARG). The specificity of [18F]JNJ-64413739 was confirmed by performing blocking experiments with the P2X7 antagonist JNJ-54175446. Results: Brain regions of rats injected with LPS had a significantly increased uptake (34 % ± 3 % s.e.m., p = 0.036, t test, standardized uptake value measured over the entire scanning period) of [18F]JNJ-64413739 relative to the corresponding brain regions of control animals injected with phosphate-buffered saline (PBS). The uptake in the contralateral regions and cerebellum was not significantly different between the groups of animals. The increase in uptake of [18F]JNJ-64413739 at the LPS-injected site observed by PET imaging was concordant with ex vivo ARG, upregulation of neuroinflammatory biomarkers, and elevated P2X7 expression levels. Conclusions: While further work is needed to study [18F]JNJ-64413739 in other types of neuroinflammation, the current results favorably characterize [18F]JNJ-64413739 as a potential PET tracer of central neuroinflammation.
关键词： Lipopolysaccharide,Rats,Positron emission tomography (PET),PET imaging,P2X7 receptor,LPS,[18F]JNJ-64413739,Neuroinflammation
更新于2025-09-23 15:22:29
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Dynamic Photo-Electro-Thermal Modeling of Light-Emitting Diodes with Phosphor Coating as Light Converter
摘要： Based on the dynamic Photo-Electro-Thermal (PET) theory for LED systems, a comprehensive theory for analyzing and modeling phosphor coating in white light-emitting diodes (LEDs) as a dynamic light converter has been presented in Part-I of this paper. This Part-2 of the work provides the details of the model parameter determination, model setup and experimental verification. The procedures of obtaining the parameters in the experimental setup are explained. Using the comprehensive theory, a dynamic PET computer model of a phosphor-coated LED device has been developed. The simulation results compare well with the practical measurements, confirming the validity of the comprehensive theory in Part-1 of this paper. The new model provides novel equations for new information such as the power loss in phosphor coating and transients of the light emitted from the phosphor coating. Such information can be used for the designs of LED drivers and systems.
关键词： Phosphor-coated light-emitting diodes (PC-LED),complete PET model,photo-electro-thermal (PET) theory,light converter
更新于2025-09-23 15:22:29
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[IEEE 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Atlanta, GA (2017.10.21-2017.10.28)] 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) - Joint Reconstruction of PET Attenuation and Activity from Scattered and Unscattered Data
摘要： In previous work, we have proposed scatter-to-attenuation reconstruction for positron emission tomography (PET). Scatter-to-attenuation reconstruction aims at recovering object attenuation information in the form of spatial electron-density distributions from pairs of coincident photons, one of which has been single-scattered. One idea is to interleave scatter-to-attenuation reconstruction, which inputs an activity distribution and outputs an attenuation map, with trues-to-activity reconstruction, which inputs said attenuation map and outputs an improved activity distribution. However, major uncertainties regarding the applicability of this approach revolve around a) the unknown impact of the initial activity estimate; b) evaluation of reconstructed activity distributions, and c) convergence to the correct solution. Methods: Using low-dimensional simulated PET data (mouse-sized, 18x18-voxels phantom), we start with mostly uniform initial activity and attenuation estimates and iteratively apply maximum-likelihood expectation-maximization (MLEM) and a maximum-likelihood gradient-ascent (MLGA) algorithm to update activity (from unscattered data) and attenuation (from scattered data), respectively. We evaluate results in terms of log-likelihoods of the expected scatter histograms, and normalized mean squared errors with respect to reference image-space distributions of activity and attenuation. Results: In our study, both attenuation and activity converged to the reference distributions, despite MLEM and MLGA starting with incorrect attenuation and activity estimates, respectively. Conclusion: The MLGA scatter-to-attenuation reconstruction algorithm, in combination with MLEM trues-to-activity reconstruction, jointly reconstructs attenuation maps and attenuation-corrected activity distributions from scattered and unscattered coincidences without reliance on a-priori information about the activity distribution.
关键词： image reconstruction,PET,attenuation,Compton scattering,algorithms
更新于2025-09-23 15:22:29