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Background: Respiratory motion is known to deteriorate positron emission tomography (PET) images and may lead to potential diagnostic errors when a standardized uptake value (SUV) cut-off threshold is used to discriminate between benign and malignant lesions.
Purpose: To evaluate and compare ungated and respiratory-gated 18F-fluorodeoxyglucose PET/computed tomography (CT) methods for the characterization of pulmonary nodules.
Material And Methods: The list-mode acquisition during respiratory-gated PET was combined with a short breath-hold CT scan to form the CT-based images. We studied 48 lesions in 43 patients. PET images were analyzed in terms of the maximum SUV (SUV(max)) and the lesion location.
Results: Using receiver-operating characteristic (ROC) curves, the optimal SUV cut-off thresholds for the ungated and CT-based methods were calculated to be 2.0 and 2.2, respectively. The corresponding sensitivity values were 83% and 92%, respectively, with a specificity of 67% for both methods. The two methods gave equivalent performance levels for the upper and middle lobes (sensitivity 93%, specificity 62%). They differed for the lower lobes, where the CT-based method outperformed the ungated method (sensitivity values of 90% and 70%, respectively, and a specificity of 73% with both methods) - especially for lesions smaller than 15 mm.
Conclusion: The CT-based method increased sensitivity and did not diminish specificity, compared with the ungated method. It was more efficient than the ungated method for imaging the lower lobes and smallest lesions, which are most affected by respiratory motion.
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http://dx.doi.org/10.1258/ar.2011.110018 | DOI Listing |
NMR Biomed
September 2025
Department of Radiology, University of Michigan, Ann Arbor, Michigan, USA.
The aim of this study is to enable high temporal resolution functional cardiac imaging without breathholds or electrocardiogram (ECG) gating. Real-time MRI is essential for assessing heart function in patients with limited breathhold capacity or arrhythmias that preclude breathheld ECG-gated cine scans. The Time-Dependent Deep Image Prior (Time-DIP) method is a promising reconstruction for dynamic MRI, combining a nonlinear manifold with zero-shot deep learning.
View Article and Find Full Text PDFMagn Reson Med
October 2025
Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Purpose: Renal metabolic rate of oxygen (rMRO) reflects the kidney's metabolic efficiency, making it a potential biomarker for early-stage kidney disease. This study introduces an ungated, free-breathing MRI sequence in comparison to its breath-hold counterpart to noninvasively measure whole-organ rMRO.
Methods: Free-breathing (FB) K-MOTIVE sequence (kidney metabolism of oxygen via T and interleaved velocity encoding) was developed to simultaneously measure renal blood flow rate (BFR) and T of blood water using the conservation of mass.
Sci Rep
May 2025
Dynamic Omics, Center for Genomics Research, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK.
Cell populations in flow cytometry are typically identified via visual manual gating, a time-consuming and error-prone approach to select subpopulations based on expression of cellular markers. Batch processing can be used to automate the analysis of bimodally distributed data but underperforms with highly-variable or continuously-expressed markers. We developed a visual pattern recognition automated gating tool, BD ElastiGate Software (hereafter ElastiGate), to recapitulate the visual process of manual gating by automatically adjusting gates to capture local variability.
View Article and Find Full Text PDFArXiv
May 2025
Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, United States.
Real-time (RT) dynamic MRI plays a vital role in capturing rapid physiological processes, offering unique insights into organ motion and function. Among these applications, RT cine MRI is particularly important for functional assessment of the heart with high temporal resolution. RT imaging enables free-breathing, ungated imaging of cardiac motion, making it a crucial alternative for patients who cannot tolerate conventional breath-hold, ECG-gated acquisitions.
View Article and Find Full Text PDFMed Phys
July 2025
Department of Nuclear Medicine, National Clinical Research Center for Cancer, Tianjin Cancer Hospital Airport Hospital, Tianjin, China.
Background: Data-driven gating (DDG) is an emerging technology that can reduce the respiratory motion artifacts in positron emission tomography (PET) images.
Purpose: The aim of this study is to use phantom and patient data to validate the performance of DDG with a motion correction algorithm based on the reconstruct, register, and average (RRA) method.
Methods: A customized motion platform drove the phantom (five spheres with diameters of 10-28 mm) using a periodic motion that had a duration of 3-5 s and amplitudes of 2-4 cm.