Whole-Body PET/CT Studies with Lowered 18F-FDG Doses: The Influence of Body Mass Index in Dose Reduction

Abstract BackgroundTime-of-flight (TOF) PET technology determines a reduction in the noise and improves the reconstructed image quality in low counts acquisitions, such as in overweight patients, allowing a reduction of administered activity and/or imaging time. However, international guidelines and recommendations on 18F-fluoro-2-deoxyglucose (FDG) activity administration scheme are old or only partially account for TOF technology and advanced reconstruction modalities. The aim of this study was to optimize FDG whole-body studies on a TOF PET/CT scanner by using a multivariate approach to quantify how physical figures of merit related to image quality change with acquisition/reconstruction/patient-dependent parameters in a phantom experiment. MethodsThe NEMA-IQ phantom was used to evaluate contrast recovery coefficient (CRC), background variability (BV) and contrast-to-noise ratio (CNR) as a function of changing emission scan duration (ESD), activity concentration (AC), target internal diameter (ID), target-background activity ratio (TBR), and body mass index (BMI). The phantom was filled with an average concentration of 5.3 kBq/mL of FDG solution and the spheres with TBR of 21.2, 8.8, and 5.0 in 3 different sessions. Images were acquired at varying background activity concentration from 5.1 to 1.3 kBq/mL and images were reconstructed for ESD of 30-151 seconds per bed position with and without Point Spread Function (PSF) correction. The parameters were all considered in a single analysis using multiple linear regression methods. ResultsAs expected, CRC depended only on sphere ID and on PSF application, while BV depended on sphere ID, ESD, AC and BMI of the phantom, in order of decreasing relevance. Noteworthy, ESD and AC resulted as the most significant predictors of CNR variability with a similar relevance, followed by the weight of the patient and TBR of the lesion. ConclusionsAC and ESD proved to be effective tools in modulating CNR. ESD could be increased rather than AC to improve image quality in overweight/obese patients to fulfil ALARA principles.

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COMPARISON OF VARIOUS 18F-FDG PET/CT ACQUISITION PROTOCOLS IN CHILDREN WITH HODGKIN’S LYMPHOMA

PEDIATRIA Journal named after G N SPERANSKY ◽

10.24110/0031-403x-2021-100-3-28-34 ◽

2021 ◽

Vol 100 (3) ◽

pp. 28-34

Author(s):

Yu.N. Likar ◽

◽

E.D. Kireeva ◽

А. Kailash ◽

M.Ya. Yadgarov ◽

...

Keyword(s):

Hodgkin’S Lymphoma ◽

Ct Scanning ◽

Early Response ◽

Diagnostic Value ◽

Hodgkin's Lymphoma ◽

Whole Body ◽

Pet Ct ◽

Scanning Area ◽

18F Fdg ◽

Ct Studies

In adults with oncological diseases, most PET/CT studies with 18F-FDG are performed using a scanning protocol with a reduced scanning area (r-PET/CT). In pediatric oncology, PET/CT with 18F-FDG is recommended to be performed in the «whole body» mode. We hypothesized that the use of r-PET/CT in children with Hodgkin's lymphoma (HL) may be sufficient without loss of diagnostic value. Materials and methods of research: a comparative analysis of PET/CT scanning protocols in «whole body» mode and r-PET/CT mode in children with HL was carried out. The retrospective analysis included 105 patients aged 0–18 years. All patient underwent primary whole-body PET/CT examinations at the time of initial staging and intermediate follow-up PET/CT scan after 2-cycle of chemotherapy. 210 PET/CT studies were retrospectively analyzed. Results: in 94 (89,5%) of 105 patients the identified lesions were localized within the area of the field-of-view of r-PET/CT, and additional lesions detected in 11 (10,5%) patients in the whole-body PET/CT examinations have not affected the results of staging and management. Conclusion: the detection of additional foci of pathological metabolic activity beyond r-PET/CT has no further impact on the stage of the disease, the protocol of treatment and the evaluation of the early response to the therapy. The advantage of r-PET/CT protocol is the reduction in radiation exposure and study time, which is very important for pediatric patients with HL.

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The role of activity, scan duration and patient’s body mass index in the optimization of FDG imaging protocols on a TOF-PET/CT scanner

EJNMMI Physics ◽

10.1186/s40658-021-00380-9 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Roberta Matheoud ◽

Naema Al-Maymani ◽

Alessia Oldani ◽

Gian Mauro Sacchetti ◽

Marco Brambilla ◽

...

Keyword(s):

Body Mass Index ◽

Image Quality ◽

Body Mass ◽

Activity Concentration ◽

Background Activity ◽

Whole Body ◽

Internal Diameter ◽

Ct Scanner ◽

Pet Ct ◽

Tof Pet

Abstract Background Time-of-flight (TOF) PET technology determines a reduction in the noise and improves the reconstructed image quality in low count acquisitions, such as in overweight patients, allowing a reduction of administered activity and/or imaging time. However, international guidelines and recommendations on the 18F-fluoro-2-deoxyglucose (FDG) activity administration scheme are old or only partially account for TOF technology and advanced reconstruction modalities. The aim of this study was to optimize FDG whole-body studies on a TOF-PET/CT scanner by using a multivariate approach to quantify how physical figures of merit related to image quality change with acquisition/reconstruction/patient-dependent parameters in a phantom experiment. Methods The NEMA-IQ phantom was used to evaluate contrast recovery coefficient (CRC), background variability (BV) and contrast-to-noise ratio (CNR) as a function of changing emission scan duration (ESD), activity concentration (AC), target internal diameter (ID), target-background activity ratio (TBR) and body mass index (BMI). The phantom was filled with an average concentration of 5.3 kBq/ml of FDG solution and the spheres with TBR of 21.2, 8.8 and 5.0 in 3 different sessions. Images were acquired at varying background activity concentration from 5.1 to 1.3 kBq/ml, and images were reconstructed for ESD of 30–151 s per bed position with and without point spread function (PSF) correction. The parameters were all considered in a single analysis using multiple linear regression methods. Results As expected, CRC depended only on sphere ID and on PSF application, while BV depended on sphere ID, ESD, AC and BMI of the phantom, in order of decreasing relevance. Noteworthy, ESD and AC resulted as the most significant predictors of CNR variability with a similar relevance, followed by the BMI of the patient and TBR of the lesion. Conclusions AC and ESD proved to be effective tools in modulating CNR. ESD could be increased rather than AC to improve image quality in overweight/obese patients to fulfil ALARA principles.

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Optimal CT Number Range for Adipose Tissue When Determining Lean Body Mass in Whole-Body F-18 FDG PET/CT Studies

Nuclear Medicine and Molecular Imaging ◽

10.1007/s13139-012-0175-3 ◽

2012 ◽

Vol 46 (4) ◽

pp. 294-299 ◽

Cited By ~ 9

Author(s):

Woo Hyoung Kim ◽

Chang Guhn Kim ◽

Dae-Weung Kim

Keyword(s):

Adipose Tissue ◽

Lean Body Mass ◽

Body Mass ◽

Fdg Pet ◽

Whole Body ◽

Ct Number ◽

Number Range ◽

Pet Ct ◽

Fdg Pet Ct ◽

Ct Studies

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Frequency and clinical implications of incidental new primary cancers detected on true whole-body 18F-FDG PET/CT studies

Nuclear Medicine Communications ◽

10.1097/mnm.0b013e32835f163f ◽

2013 ◽

Vol 34 (4) ◽

pp. 333-339 ◽

Cited By ~ 8

Author(s):

Ronnie Sebro ◽

Carina Mari Aparici ◽

Miguel Hernandez Pampaloni

Keyword(s):

Fdg Pet ◽

Whole Body ◽

Clinical Implications ◽

Pet Ct ◽

18F Fdg ◽

Fdg Pet Ct ◽

Ct Studies

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PET/CT

Nuklearmedizin ◽

10.1055/s-0038-1625216 ◽

2005 ◽

Vol 44 (S 01) ◽

pp. S51-S57 ◽

Cited By ~ 12

Author(s):

T. Beyer ◽

G. Brix

Keyword(s):

Diagnostic Accuracy ◽

Radiation Exposure ◽

Dose Reduction ◽

Pet Imaging ◽

Clinical Studies ◽

Review Article ◽

Whole Body ◽

High Radiation ◽

Radiation Burden ◽

Pet Ct

Summary:Clinical studies demonstrate a gain in diagnostic accuracy by employing combined PET/CT instead of separate CT and PET imaging. However, whole-body PET/CT examinations result in a comparatively high radiation burden to patients and thus require a proper justification and optimization to avoid repeated exposure or over-exposure of patients. This review article summarizes relevant data concerning radiation exposure of patients resulting from the different components of a combined PET/CT examination and presents different imaging strategies that can help to balance the diagnostic needs and the radiation protection requirements. In addition various dose reduction measures are discussed, some of which can be adopted from CT practice, while others mandate modifications to the existing hardand software of PET/CT systems.

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A method for evaluation of patient-specific lean body mass from limited-coverage CT images and its application in PERCIST: comparison with predictive equation

EJNMMI Physics ◽

10.1186/s40658-021-00358-7 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Jingjie Shang ◽

Zhiqiang Tan ◽

Yong Cheng ◽

Yongjin Tang ◽

Bin Guo ◽

...

Keyword(s):

Lean Body Mass ◽

Body Mass ◽

Whole Body ◽

Patient Specific ◽

Predictive Equation ◽

Reference Standard ◽

Pet Ct ◽

Before And After ◽

Percist 1.0 ◽

Limited Coverage

Abstract Background Standardized uptake value (SUV) normalized by lean body mass ([LBM] SUL) is recommended as metric by PERCIST 1.0. The James predictive equation (PE) is a frequently used formula for LBM estimation, but may cause substantial error for an individual. The purpose of this study was to introduce a novel and reliable method for estimating LBM by limited-coverage (LC) CT images from PET/CT examinations and test its validity, then to analyse whether SUV normalised by LC-based LBM could change the PERCIST 1.0 response classifications, based on LBM estimated by the James PE. Methods First, 199 patients who received whole-body PET/CT examinations were retrospectively retrieved. A patient-specific LBM equation was developed based on the relationship between LC fat volumes (FVLC) and whole-body fat mass (FMWB). This equation was cross-validated with an independent sample of 97 patients who also received whole-body PET/CT examinations. Its results were compared with the measurement of LBM from whole-body CT (reference standard) and the results of the James PE. Then, 241 patients with solid tumours who underwent PET/CT examinations before and after treatment were retrospectively retrieved. The treatment responses were evaluated according to the PE-based and LC-based PERCIST 1.0. Concordance between them was assessed using Cohen’s κ coefficient and Wilcoxon’s signed-ranks test. The impact of differing LBM algorithms on PERCIST 1.0 classification was evaluated. Results The FVLC were significantly correlated with the FMWB (r=0.977). Furthermore, the results of LBM measurement evaluated with LC images were much closer to the reference standard than those obtained by the James PE. The PE-based and LC-based PERCIST 1.0 classifications were discordant in 27 patients (11.2%; κ = 0.823, P=0.837). These discordant patients’ percentage changes of peak SUL (SULpeak) were all in the interval above or below 10% from the threshold (±30%), accounting for 43.5% (27/62) of total patients in this region. The degree of variability is related to changes in LBM before and after treatment. Conclusions LBM algorithm-dependent variability in PERCIST 1.0 classification is a notable issue. SUV normalised by LC-based LBM could change PERCIST 1.0 response classifications based on LBM estimated by the James PE, especially for patients with a percentage variation of SULpeak close to the threshold.

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