Can the BMI-based dose regimen be used to reduce injection activity and to obtain a constant image quality in oncological patients by 18F-FDG total-body PET/CT imaging?

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, SNR L ) was obtained through manually drawing ROIs and normalized (SNR norm ) by the injected activity and acquisition time. And fits of SNR norm 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 SNR L . And thus, an optimized regimen was proposed and validated by a second patient cohort with prospectively enrolled 38 oncological patients. ResultsThe linear fit showed SNR norm was the strongest correlation (R 2 = 0.69) with the BMI than other patient-dependent parameters. The qualitative assessment revealed a SNR L 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 SNR L no longer decreased with the increase of BMI. There was no significant difference of the image quality, the SNR L , 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. ConclusionThe study recommended a quadratic relation between the 18 F-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.

Exploration of the total-body PET/CT reconstruction protocol with ultra-low 18F-FDG activity over a wide range of patient body mass indices

“…Previous studies show that patients with a larger BMI consistently generate poorer image quality when using OSEM reconstruction [ 17 , 24 ]. Our previous study also showed that the acceptability of the SNR L should be more than 14.0 to meet the needs of image quality [ 25 ]. Consistent with the previous study, the SNR of the obese group could also could meet the need for image quality in the OSEM2 and HYPER Iterative groups with a 15-min duration, whereas OSEM3 showed image with sub-optimal noise.…”

The predictive value of total-body PET/CT in non-small cell lung cancer for the PD-L1 high expression

“…The newest total-body PET/CT can achieve lower injection dose, faster scanning speed, and higher resolution than the others (15,40,41). Therefore, it is more valuable in clinical application.…”

“…Recently, the total-body PET/CT, uEXPLORER (United Imaging Healthcare, Shanghai, China) with the 194-cmlong Field of View (FOV), has ultrahigh system sensitivity and spatial resolution. Thus, it dramatically improves image quality and ability to detect small lesions and distant metastases (14,15). Regarding semiquantitative parameters, several studies have found that the standard uptake value ratio (SUR) is a better predictive index than tumor maximum standard uptake value (SUVmax) (16)(17)(18)(19).…”

A personal acquisition time regimen of 68Ga-DOTATATE total-body PET/CT in patients with neuroendocrine tumor (NET): A feasibility study.

“…The image quality was scored from 3 perspectives: the overall impression of the image quality, the image noise, and the lesion detectability. Score were based on a 5-point Likert scale, as follows: Score 1, image with non-diagnostic quality, excessive noise, or unfavorable lesion contrast; Score 2, acceptable image but with sub-optimal noise and lesion depiction leading to impaired diagnostic con dence; Score 3, image with quality equivalent to those used in clinical practice; Score 4, image with quality superior to the average image quality; Score 5, image with excellent quality, optimal noise, sharp lesion depiction, and free of artifact, providing diagnosis with full con dence [11]. A score of 3 was deemed as acceptable image quality in routine clinical practice in our center.…”

“…Additionally, the injection activity of the tracer, acquisition time, and patient-speci c photon attenuation, particularly for large body masses, can in uence image quality. Regarding constant acceptable image quality, we previously investigated the in uence of patient size on image quality and proposed a dose regimen based on BMI, demonstrating the feasibility of constant image quality for 18 F-FDG total-body PET/CT [11]. In addition, adjusting the duration time per bed position based on scanner sensitivity and patient-speci c attenuation might result in uniform image noise [12].…”