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  • 1
    In: BMC Cancer, Springer Science and Business Media LLC, Vol. 22, No. 1 ( 2022-08-18)
    Abstract: New-generation silicon-photomultiplier (SiPM)-based PET/CT systems exhibit an improved lesion detectability and image quality due to a higher detector sensitivity. Consequently, the acquisition time can be reduced while maintaining diagnostic quality. The aim of this study was to determine the lowest 18 F-FDG PET acquisition time without loss of diagnostic information and to optimise image reconstruction parameters (image reconstruction algorithm, number of iterations, voxel size, Gaussian filter) by phantom imaging. Moreover, patient data are evaluated to confirm the phantom results. Methods Three phantoms were used: a soft-tissue tumour phantom, a bone-lung tumour phantom, and a resolution phantom. Phantom conditions (lesion sizes from 6.5 mm to 28.8 mm in diameter, lesion activity concentration of 15 kBq/mL, and signal-to-background ratio of 5:1) were derived from patient data. PET data were acquired on an SiPM-based Biograph Vision PET/CT system for 10 min in list-mode format and resampled into time frames from 30 to 300 s in 30-s increments to simulate different acquisition times. Different image reconstructions with varying iterations, voxel sizes, and Gaussian filters were probed. Contrast-to-noise-ratio (CNR), maximum, and peak signal were evaluated using the 10-min acquisition time image as reference. A threshold CNR value ≥ 5 and a maximum (peak) deviation of ± 20% were considered acceptable. 20 patient data sets were evaluated regarding lesion quantification as well as agreement and correlation between reduced and full acquisition time standard uptake values (assessed by Pearson correlation coefficient, intraclass correlation coefficient, Bland–Altman analyses, and Krippendorff’s alpha). Results An acquisition time of 60 s per bed position yielded acceptable detectability and quantification results for clinically relevant phantom lesions ≥ 9.7 mm in diameter using OSEM-TOF or OSEM-TOF+PSF image reconstruction, a 4-mm Gaussian filter, and a 1.65 × 1.65 x 2.00-mm 3 or 3.30 × 3.30 x 3.00-mm 3 voxel size. Correlation and agreement of patient lesion quantification between full and reduced acquisition times were excellent. Conclusion A threefold reduction in acquisition time is possible. Patients might benefit from more comfortable examinations or reduced radiation exposure, if instead of the acquisition time the applied activity is reduced.
    Type of Medium: Online Resource
    ISSN: 1471-2407
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2041352-X
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  • 2
    Online Resource
    Online Resource
    S. Karger AG ; 2022
    In:  Oncology Research and Treatment Vol. 45, No. 1-2 ( 2022), p. 18-25
    In: Oncology Research and Treatment, S. Karger AG, Vol. 45, No. 1-2 ( 2022), p. 18-25
    Abstract: 〈 b 〉 〈 i 〉 Background: 〈 /i 〉 〈 /b 〉 A variety of therapeutic approaches are employed to treat patients suffering from breast cancer. Likewise, a broad spectrum of imaging ligands has been introduced for noninvasive positron emission tomography/computed tomography (PET/CT) imaging to enable comprehensive tumor characterization and more accurate response evaluation. 〈 b 〉 〈 i 〉 Summary: 〈 /i 〉 〈 /b 〉 In recent years, novel radioactively labeled ligands have been developed for PET/CT imaging in metastatic breast cancer. One promising tracer is [ 〈 sup 〉 18 〈 /sup 〉 F]fluoroestradiol, which was recently approved by the Food and Drug Administration. It can be used for a whole-body assessment of estrogen receptor status. Another radionuclide currently under development is [ 〈 sup 〉 68 〈 /sup 〉 Ga]Ga-fibroblast-activation-protein inhibitor. In addition to new radionuclides, the field of application for existing tracers like [ 〈 sup 〉 18 〈 /sup 〉 F]fluorodeoxyglucose (FDG) was broadened. It has been shown that an early therapeutic response to various therapies can be detected by [ 〈 sup 〉 18 〈 /sup 〉 F]FDG PET/CT, which leads to early treatment optimization. 〈 b 〉 〈 i 〉 Key Message: 〈 /i 〉 〈 /b 〉 In this review, we highlighted new tracers and applications of PET/CT imaging as well as therapeutic approaches in patients with advanced breast cancer. Furthermore, we give an outlook on the application of artificial intelligence, immunoPET, and liquid biopsy.
    Type of Medium: Online Resource
    ISSN: 2296-5270 , 2296-5262
    Language: English
    Publisher: S. Karger AG
    Publication Date: 2022
    detail.hit.zdb_id: 2749752-5
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  • 3
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2022
    In:  European Journal of Nuclear Medicine and Molecular Imaging Vol. 49, No. 13 ( 2022-11), p. 4503-4515
    In: European Journal of Nuclear Medicine and Molecular Imaging, Springer Science and Business Media LLC, Vol. 49, No. 13 ( 2022-11), p. 4503-4515
    Abstract: Both digital positron emission tomography (PET) detector technologies and artificial intelligence based image post-reconstruction methods allow to reduce the PET acquisition time while maintaining diagnostic quality. The aim of this study was to acquire ultra-low-count fluorodeoxyglucose (FDG) ExtremePET images on a digital PET/computed tomography (CT) scanner at an acquisition time comparable to a CT scan and to generate synthetic full-dose PET images using an artificial neural network. Methods This is a prospective, single-arm, single-center phase I/II imaging study. A total of 587 patients were included. For each patient, a standard and an ultra-low-count FDG PET/CT scan (whole-body acquisition time about 30 s) were acquired. A modified pix2pixHD deep-learning network was trained employing 387 data sets as training and 200 as test cohort. Three models (PET-only and PET/CT with or without group convolution) were compared. Detectability and quantification were evaluated. Results The PET/CT input model with group convolution performed best regarding lesion signal recovery and was selected for detailed evaluation. Synthetic PET images were of high visual image quality; mean absolute lesion SUV max (maximum standardized uptake value) difference was 1.5. Patient-based sensitivity and specificity for lesion detection were 79% and 100%, respectively. Not-detected lesions were of lower tracer uptake and lesion volume. In a matched-pair comparison, patient-based (lesion-based) detection rate was 89% (78%) for PERCIST (PET response criteria in solid tumors)-measurable and 36% (22%) for non PERCIST-measurable lesions. Conclusion Lesion detectability and lesion quantification were promising in the context of extremely fast acquisition times. Possible application scenarios might include re-staging of late-stage cancer patients, in whom assessment of total tumor burden can be of higher relevance than detailed evaluation of small and low-uptake lesions.
    Type of Medium: Online Resource
    ISSN: 1619-7070 , 1619-7089
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2098375-X
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  • 4
    In: European Journal of Nuclear Medicine and Molecular Imaging, Springer Science and Business Media LLC, Vol. 49, No. 10 ( 2022-08), p. 3373-3386
    Abstract: The determination of the glomerular filtration rate (GFR) is decisive for a variety of clinical issues, for example, to monitor the renal function in radionuclide therapy patients. Renal scintigraphy using glomerularly filtered tracers allows combined acquisition of renograms and GFR estimation but requires repeated blood sampling for several hours. In contrast, dynamic PET imaging using the glomerularly filtered tracer [ 68 Ga]Ga-DOTA bears the potential to non-invasively estimate the GFR by compartmental kinetic modelling. Here, we report the, to our knowledge, first comparison of human renal dynamic [ 68 Ga]Ga-DOTA PET imaging in comparison to renal scintigraphy and compare PET-derived to serum creatinine-derived GFR measurements. Methods Dynamic [ 68 Ga]Ga-DOTA PET data were acquired for 30 min immediately after tracer injection in 12 patients. PET and renal scintigraphy images were visually interpreted in a consensus read by three nuclear medicine physicians. The functional renal cortex was segmented to obtain time-activity curves. The arterial input function was estimated from the PET signal in the abdominal aorta. Single-compartmental tracer kinetic modelling was performed to calculate the GFR using complete 30-min (GFR PET-30 ) and reduced 15-min PET data sets (GFR PET-15 ) to evaluate whether a shorter acquisition time is sufficient for an accurate GFR estimation. A modified approach excluding minutes 2 to 10 was applied to reduce urinary spill-over effects. Serum creatinine-derived GFR CKD (CKD-EPI-formula) was used as reference standard. Results PET image interpretation revealed the same findings as conventional scintigraphy (2/12 patients with both- and 1/12 patients with right-sided urinary obstruction). Model fit functions were substantially improved for the modified approach to exclude spill-over. Depending on the modelling approach, GFR CKD and both GFR PET-30 and GFR PET-15 were well correlated with interclass correlation coefficients (ICCs) from 0.74 to 0.80 and Pearson’s correlation coefficients (PCCs) from 0.74 to 0.81. For a subgroup of patients with undisturbed urinary efflux ( n  = 9), correlations were good to excellent (ICCs from 0.82 to 0.95 and PCCs from 0.83 to 0.95). Overall, GFR PET-30 and GFR PET-15 were excellently correlated (ICCs from 0.96 to 0.99 and PCCs from 0.96 to 0.99). Conclusion Renal [ 68 Ga]Ga-DOTA PET can be a suitable alternative to conventional scintigraphy. Visual assessment of PET images and conventional renograms revealed comparable results. GFR values derived by non-invasive single-compartmental-modelling of PET data show a good correlation to serum creatinine-derived GFR values. In patients with undisturbed urinary efflux, the correlation was excellent. Dynamic PET data acquisition for 15 min is sufficient for visual evaluation and GFR derivation.
    Type of Medium: Online Resource
    ISSN: 1619-7070 , 1619-7089
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2098375-X
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