scholarly journals Exploration of Optimal Reconstruction Parameters for 18F-FDG Total-body PET/CT with Ultra-low Activity Injection

2021 ◽  
Author(s):  
Xiuli Sui ◽  
Hui Tan ◽  
Haojun Yu ◽  
Yiqiu Zhang ◽  
Pengcheng Hu ◽  
...  
Keyword(s):  
Image Quality ◽  
Expectation Maximization ◽  
Lesion Size ◽  
Pet Ct ◽  
Quality Image ◽  
Optimal Reconstruction ◽  
Total Body ◽  
Low Activity ◽  
Lesion Conspicuity ◽  
Reconstruction Time

Abstract PURPOSE To explorer the optimal reconstruction parameters in oncologic 18 F-FDG total-body PET/CT studies with ultra-low activity injection. METHODS A total of 204 reconstructed PET images of 34 patients with a total of 58 lesions were analyzed by two experienced nuclear medicine physicians. Images were reconstructed with ordered subset expectation maximization (OSEM) algorithm (2 and 3 iterations) including time-of-flight (TOF) and point spread function (PSF) corrections and regularization ordered subset expectation maximization (ROSEM) (b-values of 0.3, 0.4, 0.5, and 0.6). General image quality was assessed using the five-point method including overall image quality, image clarity, noise, and lesion conspicuity. Image noise, signal-to-noise ratio, lesion size, SUVmax, SUVpeak and T/N were quantitatively analyzed by the third reader who did not participate in subjective image assessment. RESULTS In objective image quality indicators, noise decreased and a continuous increase of SNR with incremental β-values (0.3,0.4, 0.5 and 0.6) compared with OSEM3. In subjective image quality, OSEM2, ROSEM0.5 and ROSEM0.6 scored higher (all P<0.001) in overall image quality, image contrast and noise. The scores of ROSEM reconstructions were all higher in lesion conspicuity compared with OSEM3 (all P<0.001). In lesion detectability, SUVmax, SUVpeak and T/N increase with β value of ROSEM increase. Compared with OSEM3, there was a negative correlation between lesion size and the percentage increase of SUVpeak in OSEM2 and ROSEM reconstructions (all P<0.01). CONCLUSION In clinical practice, we recommended OSEM reconstruction with 3 iterations with a relatively short reconstruction time and we recommend ROSEM algorithm with b of 0.5 when reconstruction time is not considered.

scholarly journals Image quality and lesion detectability in low-dose paediatric 18F-FDG scans using total-body PET/CT

2021 ◽  
Author(s):  
Ying-Ying Hu ◽  
Yu-Mo Zhao ◽  
Tao Chen ◽  
Wei-Guang Zhang ◽  
Lin-Hao Wang ◽  
...  
Keyword(s):  
Image Quality ◽  
Dose Reduction ◽  
Low Dose ◽  
Subjective Image Quality ◽  
Full Dose ◽  
Lesion Detectability ◽  
Paediatric Patients ◽  
Pet Ct ◽  
Total Body ◽  
Lesion Conspicuity

Abstract Purpose: To investigate the effects of dose reduction on image quality and lesion detectability of oncological 18F-FDG total-body PET/CT in paediatric oncological patients, and explore the minimum threshold of administered tracer activity.Methods: A total of 33 paediatric patients (weight, 8.5–58.5 kg; age 0.8–17.6 years) underwent total-body PET/CT using uEXPLORER scanner with an 18F-FDG administered dose of 3.7 MBq/kg and an acquisition time of 600 s were retrospectively enrolled. Low-dose images (0.12 – 1.85 MBq/kg) were simulated by truncating the list-mode PET data to reducing count density. Subjective image quality was rated on a 5-point scale. Semi-quantitative uptake metrics for low-dose images were assessed using region-of-interest (ROI) analysis of healthy liver and suspected lesions and were compared to full-dose images. The micro-lesion detectability was compared among the dose-dependent PET images.Results: Our analysis shows that sufficient subjective image quality and lesion conspicuity could be maintained down to 1/30th (0.12 MBq/kg) of the administered dose of 18F-FDG, where good image quality scores were given to 1/2- and 1/10- dose groups. The image noise was significantly more deranged than the overall quality and lesion conspicuity in 1/30- to 1/10-dose groups (all P < 0.05). With reduced doses, quantitative analysis of ROIs showed that SUVmax and SD in the liver increased gradually (P < 0.05), but SUVmax in the lesions and lesion-to-background ratio (LBR) showed no significant deviation down to 1/30-dose. 100% of the 18F-FDG-avid micro-lesions identified in full-dose images were localised down to 1/15-dose images; while 97% of the lesion were localized in 1/30-dose images.Conclusion: The total-body PET/CT might significantly decrease the administered dose upon maintaining the image quality and diagnostic performance of micro-lesions in paediatric patients. Data suggests that using total-body PET/CT, optimal image quality could be achieved with an administered dose-reduction down to 1/10-dose (0.37 MBq/kg).

Impact of total variation regularized expectation maximization reconstruction on the image quality of 68Ga-PSMA PET: a phantom and patient study

2021 ◽  
pp. 20201356
Author(s):  
Feng-Jiao Yang ◽  
Shu-Yue Ai ◽  
Runze Wu ◽  
Yang Lv ◽  
Hui-Fang Xie ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Image Quality ◽  
Total Variation ◽  
Expectation Maximization ◽  
Image Noise ◽  
Psma Pet ◽  
Pet Ct ◽  
Digital Pet ◽  
The Impact

Objectives: To investigate the impact of total variation regularized expectation maximization (TVREM) reconstruction on the image quality of 68Ga-PSMA-11 PET/CT using phantom and patient data. Methods: Images of a phantom with small hot sphere inserts and 20 prostate cancer patients were acquired with a digital PET/CT using list-mode and reconstructed with ordered subset expectation maximization (OSEM) and TVREM with seven penalisation factors between 0.01 and 0.42 for 2 and 3 minutes-per-bed (m/b) acquisition. The contrast recovery (CR) and background variability (BV) of the phantom, image noise of the liver, and SUVmax of the lesions were measured. Qualitative image quality was scored by two radiologists using a 5-point scale (1-poor, 5-excellent). Results: The performance of CR, BV, and image noise, and the gain of SUVmax was higher for TVREM 2 m/b groups with the penalization of 0.07 to 0.28 compared to OSEM 3 m/b group (all p < 0.05). The image noise of OSEM 3 m/b group was equivalent to TVREM 2 and 3 m/b groups with a penalization of 0.14 and 0.07, while lesions’ SUVmax increased 15 and 20%. The highest qualitative score was attained at the penalization of 0.21 (3.30 ± 0.66) for TVREM 2 m/b groups and the penalization 0.14 (3.80 ± 0.41) for 3 m/b group that equal to or greater than OSEM 3 m/b group (2.90 ± 0.45, p = 0.2 and p < 0.001). Conclusions: TVREM improves lesion contrast and reduces image noise, which allows shorter acquisition with preserved image quality for PSMA PET/CT. Advances in knowledge: TVREM reconstruction with optimized penalization factors can generate higher quality PSMA-PET images for prostate cancer diagnosis.

scholarly journals The effect of modern PET technology and techniques on the EANM paediatric dosage card

2021 ◽  
Author(s):  
John Dickson ◽  
Uta Eberlein ◽  
Michael Lassmann
Keyword(s):  
Image Quality ◽  
Field Of View ◽  
Published Data ◽  
Axial Field ◽  
Short Article ◽  
Pet Ct ◽  
Class B ◽  
Total Body ◽  
Bed Position ◽  
Pet Scanners

Abstract Aim Recent advancements in PET technology have brought with it significant improvements in PET performance and image quality. In particular, the extension of the axial field of view of PET systems, and the introduction of semiconductor technology into the PET detector, initially for PET/MR, and more recently available long-field-of-view PET/CT systems (≥ 25 cm) have brought a step change improvement in the sensitivity of PET scanners. Given the requirement to limit paediatric doses, this increase in sensitivity is extremely welcome for the imaging of children and young people. This is even more relevant with PET/MR, where the lack of CT exposures brings further dose reduction benefits to this population. In this short article, we give some details around the benefits around new PET technology including PET/MR and its implications on the EANM paediatric dosage card. Material and methods  Reflecting on EANM adult guidance on injected activities, and making reference to bed overlap and the concept of MBq.min bed−1 kg−1, we use published data on image quality from PET/MR systems to update the paediatric dosage card for PET/MR and extended axial field of view (≥ 25 cm) PET/CT systems. However, this communication does not cover the expansion of paediatric dosing for the half-body and total-body scanners that have recently come to market. Results In analogy to the existing EANM dosage card, new parameters for the EANM paediatric dosage card were developed (class B, baseline value: 10.7 MBq, minimum recommended activity 10 MBq). The recommended administered activities for the systems considered in this communication range from 11 MBq [18F]FDG for a child with a weight of 3 kg to 149 MBq [18F]FDG for a paediatric patient weight of 68 kg, assuming a scan of 3 min per bed position. The mean effective dose over all ages (1 year and older) is 2.85 mSv. Conclusion With this, recommendations for paediatric dosing are given for systems that have not been considered previously.

The image quality, lesion detectability, and acquisition time of 18F-FDG total-body PET/CT in oncological patients

2020 ◽  
Vol 47 (11) ◽  
pp. 2507-2515 ◽  
Author(s):  
Yi-Qiu Zhang ◽  
Peng-Cheng Hu ◽  
Run-Ze Wu ◽  
Yu-Shen Gu ◽  
Shu-Guang Chen ◽  
...  
Keyword(s):  
Image Quality ◽  
Acquisition Time ◽  
Lesion Detectability ◽  
Oncological Patients ◽  
Pet Ct ◽  
18F Fdg ◽  
Total Body

scholarly journals Impact of penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm for 18F-fluorocholine PET-CT regarding image quality and interpretation

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mimmi Bjöersdorff ◽  
Jenny Oddstig ◽  
Nina Karindotter-Borgendahl ◽  
Helén Almquist ◽  
Sophia Zackrisson ◽  
...  
Keyword(s):  
Image Quality ◽  
Expectation Maximization ◽  
Reconstruction Algorithm ◽  
Pet Ct

scholarly journals Prospective Image Quality and Lesion Assessment in the Setting of MR-Guided Radiation Therapy of Prostate Cancer on an MR-Linac at 1.5 T: A Comparison to a Standard 3 T MRI

Cancers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1533
Author(s):  
Haidara Almansour ◽  
Saif Afat ◽  
Victor Fritz ◽  
Fritz Schick ◽  
Marcel Nachbar ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Radiation Therapy ◽  
Image Quality ◽  
Outcome Measures ◽  
Quality Criteria ◽  
Lesion Size ◽  
Geometric Distortion ◽  
Diagnostic Confidence ◽  
Prostate Imaging ◽  
Lesion Conspicuity

The objective of this study is to conduct a qualitative and a quantitative image quality and lesion evaluation in patients undergoing MR-guided radiation therapy (MRgRT) for prostate cancer on a hybrid magnetic resonance imaging and linear accelerator system (MR-Linac or MRL) at 1.5 Tesla. This prospective study was approved by the institutional review board. A total of 13 consecutive patients with biopsy-confirmed prostate cancer and an indication for MRgRT were included. Prior to radiation therapy, each patient underwent an MR-examination on an MRL and on a standard MRI scanner at 3 Tesla (MRI3T). Three readers (two radiologists and a radiation oncologist) conducted an independent qualitative and quantitative analysis of T2-weighted (T2w) and diffusion-weighted images (DWI). Qualitative outcome measures were as follows: zonal anatomy, capsule demarcation, resolution, visibility of the seminal vesicles, geometric distortion, artifacts, overall image quality, lesion conspicuity, and diagnostic confidence. All ratings were performed on an ordinal 4-point Likert scale. Lesion conspicuity and diagnostic confidence were firstly analyzed only on MRL. Afterwards, these outcome parameters were analyzed in consensus with the MRI3T. Quantitative outcome measures were as follows: anteroposterior and right left diameter of the prostate, lesion size, PI-RADS score (Prostate Imaging—Reporting and Data System) and apparent diffusion coefficient (ADC) of the lesions. Intergroup comparisons were computed using the Wilcoxon-sign rank test and t tests. A post-hoc regression analysis was computed for lesion evaluation. Finally, inter-/intra-reader agreement was analyzed using the Fleiss kappa and intraclass correlation coefficient. For T2w images, the MRL showed good results across all quality criteria (median 3 and 4). Furthermore, there were no significant differences between MRL and MRI3T regarding capsule demarcation or geometric distortion. For the DWI, the MRL performed significantly less than MRI3T across most image quality criteria with a median ranging between 2 and 3. However, there were no significant differences between MRL and MRI3T regarding geometric distortion. In terms of lesion conspicuity and diagnostic confidence, inter-reader agreement was fair for MRL alone (Kappa = 0.42) and good for MRL in consensus with MRI3T (Kappa = 0.708). Thus, lesion conspicuity and diagnostic confidence could be significantly improved when reading MRL images in consensus with MRI3T (Odds ratio: 9- to 11-fold for the T2w images and 5- to 8–fold for the DWI) (p < 0.001). For measures of lesion size, anterior-posterior and right-left prostate diameter, inter-reader and intersequence agreement were excellent (ICC > 0.90) and there were no significant differences between MRL and MRI3T among all three readers. In terms of Prostate Imaging Reporting and Data System (PIRADS) scoring, no significant differences were observed between MRL and MRI3T. Finally, there was a significant positive linear relationship between lesion ADC measurements (r = 0.76, p < 0.01) between the ADC values measured on both systems. In conclusion, image quality for T2w was comparable and diagnostic even without administration of spasmolytic- or contrast agents, while DWI images did not reach diagnostic level and need to be optimized for further exploitation in the setting of MRgRT. Diagnostic confidence and lesion conspicuity were significantly improved by reading MRL in consensus with MRI3T which would be advisable for a safe planning and treatment workflow. Finally, ADC measurements of lesions on both systems were comparable indicating that, lesion ADC as measured on the MRL could be used as a biomarker for evaluation of treatment response, similar to examinations using MRI3T.

scholarly journals Diagnostic Performance and Image Quality of 20-second Breath-hold Total-body PET/CT Acquisition in Stage Ia Pulmonary Adenocarcinoma

2021 ◽  
Author(s):  
Yanhua Duan ◽  
Minjie Zhao ◽  
Keyu Zan ◽  
Ying Wang ◽  
Xiao Cui ◽  
...  
Keyword(s):  
Image Quality ◽  
Subgroup Analysis ◽  
Diagnostic Performance ◽  
Pulmonary Adenocarcinoma ◽  
Acquisition Time ◽  
Breath Hold ◽  
Pet Ct ◽  
Stage Ia ◽  
Total Body

Abstract PurposeThe study is to evaluate the diagnostic performance and image quality of a 20-second breath-hold (BH) 18F-FDG total-body PET acquisition compared with a free-breathing (FB) PET for stage IA pulmonary adenocarcinoma.Materials and MethodsForty-seven patients with confirmed stage IA pulmonary adenocarcinoma were enrolled. All patients underwent total-body 18F–FDG PET/CT and the acquisition time was 300 s, followed by a 20-s BH PET. A 20-s FB PET was extracted from the 300-s PET. The size and volume of lesions were measured on BHCT images. The SUVmax, tumor-to-background ratio (TBR), metabolic tumor volume (MTV), %ΔSUVmax and %ΔTBR of the lesions were measured and recorded. The lesions were further divided by distance from pleura, lesion size, and morphological characteristic for subgroup analysis. ResultsIn the cohort and subgroup analysis, the SUVmax and TBR were significantly increased with 20-BH PET compared with 300-FB PET and 20-FB PET (all p＜0.05). And the %ΔSUVmax and %ΔTBR in D1 groups (≤10 mm in distance) higher than those in D2 and D3 groups (＞10 mm). The diagnostic performance of BH PET was significantly higher than that of FB PET (all p＜0.001). The Bland-Altman plot for agreement on lesion’s volume between BH PET and CT showed good agreement than FB PET.ConclusionThe 20-s BH PET acquisition is more sensitive to quantitative and qualitative analysis for stage IA pulmonary adenocarcinoma. 20-s BH PET/CT acquisition reduces the blurring effect of respiratory motion especially for subpleural nodules (≤10 mm in distance).

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