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

Abstract Purpose PET image quality is influenced by the patient size according to the current guideline. The purpose was to propose an optimized dose regimen to yield a constant image quality independent of patient size to meet the clinical needs.Methods A first patient cohort of 78 consecutives for oncological patients (59.7±13.7 years) who underwent a total-body PET/CT scan were retrospectively enrolled to develop the regimen. The patients were equally distributed in four BMI groups according to WHO criteria. The liver SNR (Signal noise ratio, SNRL) was obtained through manually drawing ROIs and normalized (SNRnorm) by the injected activity and acquisition time. And fits of SNRnorm against different patient-dependent parameters were performed to determine the best correlating parameter and fit method. A qualitative assessment on image quality was performed using a 5-point Likert scale to determine the acceptable threshold of SNRL. And thus, an optimized regimen was proposed and validated by a second patient cohort with prospectively enrolled 38 oncological patients. Results The linear fit showed SNRnorm was the strongest correlation (R2 = 0.69) with the BMI than other patient-dependent parameters. The qualitative assessment revealed a SNRL of 14.0 as a threshold to achieve a sufficient image quality. The optimized dose regimen was determined as a quadratic relation with BMI: Injected activity = 39.2 MBq/(-0.03*BMI+1.49)2. In the validation study, the SNRL no longer decreased with the increase of BMI. There was no significant difference of the image quality, the SNRL, between different BMI groups (p > 0.05). In addition, the injected activity was reduced by 75.6±2.9 %, 72.1±4.0 %, 67.1±4.4 % and 64.8±3.5 % compared to the first cohort for the four BMI groups, respectively.Conclusion The study recommended a quadratic relation between the 18F-FDG injected activity and the patient’s BMI and propose a regimen for total-body PET imaging. In the regimen, the image quality can maintain in a constant level independent of patient size and meet the clinical requirement even with a reduced injected activity.

Download Full-text

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

10.21203/rs.3.rs-670774/v1 ◽

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).

Download Full-text

Determining the Optimal Dose of 18F-FDG for Hodgkin lymphoma Imaging on PET/CT Camera with BGO Crystals

10.21203/rs.3.rs-89841/v1 ◽

2020 ◽

Author(s):

Mirosław Dziuk ◽

Ewa Witkowska-Patena ◽

Agnieszka Giżewska ◽

Andrzej Mazurek ◽

Anna Pieczonka ◽

...

Keyword(s):

Image Quality ◽

Hodgkin Lymphoma ◽

Intraclass Correlation ◽

Rank Correlation ◽

Optimal Dose ◽

Acquisition Time ◽

Substantial Impact ◽

Pet Ct ◽

18F Fdg ◽

Phantom Studies

Abstract Purpose: We aimed to find the minimum feasible dose of fluorodeoxyglucose (18F-FDG) in positron emission tomography/computed tomography (PET/CT) of Hodgkin lymphoma patients performed on a camera with bismuth germanate (BGO) crystals.Methods: Ninety-one 18F-FDG PET/CT scans with decreasing time per bed position (2 min, 1.5 min, 1 min, 50 sec, 40 sec, 30 sec and 20 sec) were assessed to evaluate image quality. Mean administered dose was 3.0±0.1 MBq/kg and mean uptake time was 54.0±8.7 min. The series quality was subjectively marked in 1-10 scale and then ranked 1-7 based on the mean mark. Interobserver rank correlation and intraclass correlation within each series were calculated. Phantom studies were also performed to determine if reduced acquisition time can be directly translated into a reduced dose. Results: We show the longer the time of acquisition the higher the mark and rank. The interobserver agreement in ranking was 100% with kappa coefficient of 1.00 (95% CI [0.83-1.0]). The general intraclass correlation coefficient was 0.945 (95% CI [0,936-0,952]). Only the series with 2 min and 1.5 min acquisition time were appropriate for assessment (mean mark ≥7). In phantom studies there was a linear correlation between time per bed, administered activity and number of total prompts detected by a scanner. Hence, reduction of acquisition time of 25% (from 2 min to 1.5 min) could be directly translated into a 25% dose reduction (from 3.0 to 2.25 MBq/kg).Conclusions: In patients with HL, 18F-FDG dose can be reduced by up to 25% when using a BGO crystal camera, without substantial impact on image quality.

Download Full-text

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

10.21203/rs.3.rs-201348/v1 ◽

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).

Download Full-text

Feasibility of Low-Dose 68Ga-DOTATATE With Short Acquisition Time Using Total-Body PET/CT in Patients With Neuroendocrine Tumor

10.21203/rs.3.rs-667845/v1 ◽

2021 ◽

Author(s):

Jie Xiao ◽

Haojun Yu ◽

Hongyan Yin ◽

Guobin Liu ◽

Yan Hu ◽

...

Keyword(s):

Image Quality ◽

Dose Regimen ◽

Low Dose ◽

Signal To Noise Ratio ◽

Subjective Evaluation ◽

Blood Pool ◽

Acquisition Time ◽

Short Acquisition Time ◽

Pet Ct ◽

Total Body

Abstract Purpose To explore the feasibility of a low dose regimen with short acquisition time of 68Ga-DOTATATE total-body PET/CT without compromising image quality of patients with NETs. Methods Fifty-seven consecutive NETs patients who underwent 68Ga-DOTATATE total-body PET/CT, with a low dose regimen (0.8-1.2 MBq/kg) of 68Ga-DOTATATE and acquisition time of 10 min prior to any treatment, were enrolled in the present study. The PET data were split into 1 min, 2 min, 3 min, 4 min, 5 min, 8 min and 10 min reconstruction groups, referenced as R1, R2, R3, R4, R5, R8 and R10. The subjective evaluation of image quality was scored in 5-point Likert scale based on three aspects: the overall impression of the image quality, the image noise, the lesion detectability. The objective image quality was assessed by the signal-to-noise ratio of liver (SNRL), the coefficient of variation (CV), the SUVmax, SUVmean, SD of liver, mediastinal blood pool and lesion, the tumor-liver ratio (TLR), the tumor-mediastinal blood pool-ratio (TMR) of lesion. Results The sufficient subjective image quality with a score of 3.44±0.53 could be obtained at 3 min acquisition duration, with a kappa value of 0.90. In quantitative analysis, the value of SNRL is over 10 in all reconstruction groups. As the acquisition time increases, SNRL was increased and CV was decreased within 3 min, while SNRL and CV showed no significant different between R4-R10. There was no significant different in TMR and TLR of lesion between R1-R10 (all p < 0.05). Referenced as PET images of R10, 90 SSTR-positive lesions are identified, and all those lesions are found in the R1-R10 groups (100%).Conclusion The low-dose (0.8-1.2 MBq/kg) 68Ga-DOTATATE total-body PET/CT not only shortens acquisition time, but maintains a sufficient image quality for the NETs patients.

Download Full-text

Total-body 18F-FDG PET Scan in Oncological Patients: How Fast could it be?

10.21203/rs.3.rs-320600/v1 ◽

2021 ◽

Author(s):

Pengcheng Hu ◽

Yiqiu Zhang ◽

Haojun Yu ◽

Shuguang Chen ◽

Hui Tan ◽

...

Keyword(s):

Image Quality ◽

Phantom Study ◽

Pet Scan ◽

Clinical Settings ◽

Recovery Coefficient ◽

Clinical Images ◽

Oncological Patients ◽

Pet Ct ◽

Significant Difference ◽

Total Body

Abstract Purpose: The aim of the study was to explore a fast PET scan protocol of the total-body uEXPLORER scanner by assessing the image quality consistent to that of a conventional digital PET/CT scanner both from the phantom and clinical perspectives.Methods: The phantom study using a NEMA/IEC NU-2 body phantom was performed both on a total-body PET/CT (uEXPLORER) and a digital routine PET/CT (uMI 780), with hot sphere to background activity concentration ratio of 4:1. The contrast recovery coefficient (CRC), background variability (BV), recovery coefficient RCmax and RCmean were assessed and compared between that in uEXPLORER with the different scanning duration and reconstruction protocols and that in uMI 780 with clinical settings. The coefficient of variation (COV) of the uMI 780 with clinical settings were calculated and used as a threshold to determine the optimized scanning duration and reconstruction protocols were, which can provide a consistent image quality for the two scanners. And subsequently, the proposed protocol was validated by 30 oncological patients. Images acquired in uMI 780 with a 2-3 minute for each bed position were referred as G780. All PET raw data were reconstructed using data-cutting technique to simulate a 30s, 45s or 60s acquisition duration on uEXPLORER. The iterations were 2 and 3 for uEXPLORER, referred as G30s_3i, G45s_2i, G45s_3i, G60s_2i, and G60s_3i. A 5-point Likert scale was used in the qualitative analysis to assess the image quality. The image quality was also compared with the liver COV, the lesion target-to-background ratio (TBR), and the lesion signal-to-noise ratio (SNR).Results: In the phantom study, CRC, BV, RCmax and RCmean in uEXPLORER with different scanning duration and reconstruction iterations were compared with that in uMI 780 with clinical settings and a minor fluctuation was found among different scanning durations. COV of the uMI 780 with clinical settings was 11.6% and determined protocol with a 30-45s scanning duration and 2 or 3 iterations to provide a similar image quality.In the quantitative analysis on the clinical images, there was no significant difference between G780 and G45s_3i. All the other groups in uEXPLORER with a 45s- and above acquisition showed a significantly improved image quality than that in uMI 780 with clinical settings. Comparing the liver COV, there was no significantly difference between G780 and G30s_3i. And no significant difference in lesion TBR was identified between G780 and G45s_2i, while uEXPLORER had a better performance in lesion SNR compared to that in uMI 780 with clinical settings. Conclusions: This study demonstrated a fast PET protocol with a 30-45s acquisition in uEXPLORER with consistent image quality to that in uMI 780 with clinical settings.

Download Full-text