The Performance Comparison of 18F-FDG PET/MRI and 18F-FDG PET/CT for the Identification of Pancreatic Neoplasms

PURPOSE

To determine the optimal imaging tool for clinical evaluation of pancreatic neoplasm by comparing the performance of ¹⁸F-FDG PET/MRI and PET/CT.

PROCEDURES

Patients with suspected pancreatic neoplasms underwent PET/MRI and PET/CT in the same day prior to resection or endoscopic ultrasound-guided fine-needle aspiration. Histology served as the golden standard of lesion classification. Visual assessment on lesion type and lesion malignancy via PET/MRI and PET/CT images was compared. Standard uptake values (SUVs) of PET images from the two scanners were measured and their correlations were further evaluated.

RESULTS

Thirty-nine patients were included for the final analysis. In visual assessment, we found MRI achieved better performance than CT in differentiating solid and cystic neoplasms, with accuracy of 100% vs. 87%, respectively. In visual malignancy diagnosis, the accuracy of PET/CT was 92.3% for overall lesions and 90.9% for cysts, while the accuracy of PET/MRI was 92.3% and 86.4%, respectively. Besides, semi-quantitative analysis achieved better specificity than visual assessment for both hybrid modalities (100% vs. 87.5% for PET/CT; 100% vs. 81.5% for PET/MR). Furthermore, strong correlation of SUV was found between PET/CT and PET/MRI, with Pearson's correlation coefficients > 0.82.

CONCLUSIONS

In this study, we found PET/MRI and PET/CT, both using ¹⁸F-FDG as tracer, had comparable overall performance in identification of pancreatic neoplasms. Interestingly, for patients who had suspected pancreatic neoplasm but invisible FDG uptake, PET/MRI had shown exceptionally better performance, probably because MR images could detect tiny abnormal structures to improve diagnosis.

Reproducibility of Standardized Uptake Values Including Volume Metrics Between TOF-PET-MR and TOF-PET-CT

Purpose

To investigate the reproducibility of tracer uptake measurements, including volume metrics, such as metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) obtained by TOF-PET-CT and TOF-PET-MR.

Materials and Methods

Eighty consecutive patients with different oncologic diagnoses underwent TOF-PET-CT (Discovery 690; GE Healthcare) and TOF-PET-MR (SIGNA PET-MR; GE Healthcare) on the same day with single dose−18F-FDG injection. The scan order, PET-CT following or followed by PET-MR, was randomly assigned. A spherical volume of interest (VOI) of 30 mm was placed on the liver in accordance with the PERCIST criteria. For liver, the maximum and mean standard uptake value for body weight (SUV) and lean body mass (SUL) were obtained. For tumor delineation, VOI with a threshold of 40 and 50% of SUVmax was used (VOI40 and VOI50). The SUVmax, SUVmean, SUVpeak, MTV and TLG were calculated. The measurements were compared between the two scanners.

Results

In total, 80 tumor lesions from 35 patients were evaluated. There was no statistical difference observed in liver regions, whereas in tumor lesions, SUVmax, SUV mean, and SUVpeak of PET-MR were significantly underestimated (p < 0.001) in both VOI40 and VOI50. Among volume metrics, there was no statistical difference observed except TLG on VOI50 (p = 0.03). Correlation between PET-CT and PET-MR of each metrics were calculated. There was a moderate correlation of the liver SUV and SUL metrics (r = 0.63–0.78). In tumor lesions, SUVmax and SUVmean had a stronger correlation with underestimation in PET-MR on VOI 40 (SUVmax and SUVmean; r = 0.92 and 0.91 with slope = 0.71 and 0.72, respectively). In the evaluation of MTV and TLG, the stronger correlations were observed both on VOI40 (MTV and TLG; r = 0.75 and 0.92) and VOI50 (MTV and TLG; r = 0.88 and 0.95) between PET-CT and PET-MR.

Conclusion

PET metrics on TOF-PET-MR showed a good correlation with that of TOF-PET-CT. SUVmax and SUVpeak of tumor lesions were underestimated by 16% on PET-MRI. MTV with % threshold can be regarded as identical volumetric markers for both TOF-PET-CT and TOF-PET-MR.

A Simplified PET/CT Measurement Routine with Excellent Diagnostic Accuracy for the Diagnosis of Giant Cell Arteritis

We previously proposed standard uptake value (SUV) ratio-based cut-off values for [18F] fluorodeoxyglucose-positron emission tomography/computed tomography (PET/CT) for diagnosing giant cell arteritis (GCA) with high diagnostic accuracy. Here we confirm our findings in an independent cohort and report a simplified procedure for using a SUV ratio to diagnose LV-GCA. Patients with suspected GCA were consecutively included. The ‘peak SUV ratio’ was defined in a two-step approach. First, the vessel with the visually brightest radiotracer uptake in the supra-aortic (SA) and in the aorto-iliofemoral (AIF) region was identified. Here, the maximum SUV of the vessel was measured and divided by the mean SUV of the liver (SUVratio). A ratio >1.0 in the SA or >1.3 in the AIF region was scored as vasculitis. The diagnostic accuracy, sensitivity, and specificity of the ‘peak SUV ratio’ in the SA and AIF region was assessed. From 2015 to 2019, 50 patients (24 female, median age 71 years) with suspicion of GCA were included, 28 patients with GCA and 22 patients with exclusion of GCA. Peak SUV had an AUC of 0.91, a sensitivity of 0.89, and a specificity of 0.73 for diagnosing GCA. Peak SUV accuracy of the AIF arteries was lower (AUC 0.81) than of the SA arteries (AUC 0.95). Our SUV ratio cut-off values for diagnosing GCA are consistently valid, also when applied in a time-efficient clinical procedure focusing on the peak SUV ratio. The diagnostic performance of PET/CT in this validation cohort was even higher, compared to the inception cohort (AUC of 0.83).

Impact of TOF on Brain PET With Short-Lived 11C-Labeled Tracers Among Suspected Patients With AD/PD: Using Hybrid PET/MRI

Objective

To explore the impact of the time-of-flight (TOF) reconstruction on brain PET with short-lived 11C-labeled tracers in PET magnetic resonance (PET/MR) brain images among suspected patients with Alzheimer's and Parkinson's disease (AD/PD).

Methods

Patients who underwent 11C-2-ß-carbomethoxy-3-b-(4-fluorophenyl) tropane (11C-CFT) and 2-(4-N-[11C] methylaminophenyl)-6-hydroxybenzothiazole (11C-PiB) PET/MRI were retrospectively included in the study. Each PET LIST mode data were reconstructed with and without the TOF reconstruction algorithm. Standard uptake values (SUVs) of Caudate Nucleus (CN), Putamen (PU), and Whole-brain (WB) were measured. TOF and non-TOF SUVs were assessed by using paired t-test. Standard formulas were applied to measure contrast, signal-to-noise ratio (SNR), and percentage relative average difference of SUVs (%RAD-SUVs).

Results

Total 75 patients were included with the median age (years) and body mass index (BMI-kg/m2) of 60.2 ± 10.9 years and 23.9 ± 3.7 kg/m2 in 11C-CFT (n = 41) and 62.2 ± 6.8 years and 24.7 ± 2.9 kg/m2 in 11C-PiB (n = 34), respectively. Higher average SUVs and positive %RAD-SUVs were observed in CN and PU in TOF compared with non-TOF reconstructions for the two 11C-labeled radiotracers. Differences of SUVmean were significant (p < 0.05) in CN and PU for both 11C-labeled radiotracers. SUVmax was enhanced significantly in CN and PU for 11C-CFT and CN for 11C-PiB, but not in PU. Significant contrast enhancement was observed in PU for both 11C-labeled radiotracers, whereas SNR gain was significant in PU, only for 11C-PiB in TOF reconstruction.

Conclusion

Time-of-flight leads to a better signal vs. noise trade-off than non-TOF in 11C-labeled tracers between CN and PU, improving the SUVs, contrast, and SNR, which were valuable for reducing injected radiation dose. Improved timing resolution aided the rapid decay rate of short-lived 11C-labeled tracers, and it shortened the scan time, increasing the patient comfort, and reducing the motion artifact among patients with AD/PD. However, one should adopt the combined TOF algorithm with caution for the quantitative analysis because it has different effects on the SUVmax, contrast, and SNR of different brain regions.

Respiratory 4D-Gating F-18 FDG PET/CT Scan for Liver Malignancies: Feasibility in Liver Cancer Patient and Tumor Quantitative Analysis

Purpose

To evaluate the potential clinical role and effectiveness of respiratory 4D-gating F-18 FDG PET/CT scan for liver malignancies, relative to routine (3D) F-18 FDG PET/CT scan.

Materials and Methods

This study presented a prospective clinical study of 16 patients who received F-18 FDG PET/CT scan for known or suspected malignant liver lesions. Ethics approvals were obtained from the ethics committees of the Hong Kong Baptist Hospital and The Hong Kong Polytechnic University. Liver lesions were compared between the gated and ungated image sets, in terms of 1) volume measurement of PET image, 2) accuracy of maximum standardized uptake value (SUV_max), mean standardized uptake value (SUV_mean), and 3) accuracy of total lesion glycoses (TLG). Statistical analysis was performed by using a two-tailed paired Student t-test and Pearson correlation test.

Results

The study population consisted of 16 patients (9 males and 7 females; mean age of 65) with a total number of 89 lesions. The SUV_max and SUV_mean measurement of the gated PET images was more accurate than that of the ungated PET images, compared to the static reference images. An average of 21.48% (p < 0.001) reduction of the tumor volume was also observed. The SUV_max and SUV_mean of the gated PET images were improved by 19.81% (p < 0.001) and 25.53% (p < 0.001), compared to the ungated PET images.

Conclusions

We have demonstrated the feasibility of implementing 4D PET/CT scan for liver malignancies in a prospective clinical study. The 4D PET/CT scan for liver malignancies could improve the quality of PET image by improving the SUV accuracy of the lesions and reducing image blurring. The improved accuracy in the classification and identification of liver tumors with 4D PET image would potentially lead to its increased utilization in target delineation of GTV, ITV, and PTV for liver radiotherapy treatment planning in the future.

Head-to-head evaluation of [18F]FDG and [68 Ga]Ga-DOTA-FAPI-04 PET/CT in recurrent soft tissue sarcoma

Purpose

We aimed to evaluate the value of [⁶⁸ Ga]Ga-DOTA-FAPI-04 PET/CT for the diagnosis of recurrent soft tissue sarcoma (STS), compared with [¹⁸F]FDG PET/CT.

Methods

A total of 45 patients (21 females and 24 males; median age, 46 years; range, 18–71 years) with 13 subtypes of STS underwent [¹⁸F]FDG and [⁶⁸ Ga]Ga-DOTA-FAPI-04 PET/CT examination within 1 week for assessment local relapse or distant metastasis. Positive lesions on PET/CT images were verified by biopsy or 3-month follow-up. Wilcoxon matched-pairs signed-rank test was used to compare the semiquantitative values (SUV_max and TBR) of [¹⁸F]FDG and [⁶⁸ Ga]Ga-DOTA-FAPI-04 in tumor lesions, and McNemar test was applied to test for differences of both tracers.

Results

Among the 45 patients, 282 local relapses and distant metastases were identified. Compared to [¹⁸F]FDG, [⁶⁸ Ga]Ga-DOTA-FAPI-04 PET/CT detected more lesions (275 vs. 186) and outperformed in sensitivity, specificity, PPV, NPV, and accuracy for the diagnosis of recurrent lesions (P < 0.001). [⁶⁸ Ga]Ga-DOTA-FAPI-04 demonstrated significantly higher values of SUV_max and TBR than [¹⁸F]FDG PET/CT in liposarcoma (P = 0.011 and P < 0.001, respectively), malignant solitary fibrous tumor (MSFT) (P < 0.001 and P < 0.001, respectively), and interdigitating dendritic cell sarcoma (IDCS) (P < 0.001and P < 0.001, respectively). While mean SUV_max and TBR presented favorable uptake of [¹⁸F]FDG over [⁶⁸ Ga]Ga-DOTA-FAPI-04 in undifferentiated pleomorphic sarcoma (UPS) (P = 0.003 and P < 0.001, respectively) and rhabdomyosarcoma (RMS) (P < 0.001 and P < 0.001, respectively).

Conclusion

[⁶⁸ Ga]Ga-DOTA-FAPI-04 PET/CT is a promising new imaging modality for recurrent surveillance of STS, and compares favorably with [¹⁸F]FDG for identifying recurrent lesions of liposarcoma, MSFT, and IDCS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-022-05700-4.

Clinical and pathological predictors for FDG-PET/CT avidity in patients with marginal zone lymphoma-a retrospective cohort study

BACKGROUND

The clinical value of FDG-PET/CT for staging and monitoring treatment response in patients with aggressive lymphoma is well established. Conversely, its role in the assessment and management of marginal zone lymphoma (MZL) is less conclusive. We aimed to assess clinical, laboratory, and pathological predictors for FDG uptake in these patients, in an attempt to identify MZL patients whose management will benefit from this imaging modality.

METHODS

In this single-center, retrospective cohort study, we included all adult patients diagnosed with MZL at the Rabin Medical Center between January 2006 and December 2020 who underwent FDG-PET/CT at the time of diagnosis. Primary outcomes were FDG avidity (defined as a visual assessment of at least moderate intensity), SUVmax, and SUVliver. Variables such as advanced clinical stage, primary disease site, hemoglobin level (Hb), platelet count (Plt), serum albumin, LDH level, β-2 microglobulin, and Ki 67 index were evaluated univariate and multivariate analysis using logistic and linear regression models. Association between FDG avidity and progression-free and overall survival was evaluated using Kaplan-Meier curves and Cox regression analysis.

RESULTS

A total of 207 MZL patients were included in this study, 76 of whom (36.7%) had FDG-avid disease. Baseline patients' characteristics such as age, gender, and comorbid conditions were similar between patients with and without significant FDG uptake. In a multivariate logistic regression model, non-gastric MALT (OR 4.2, 95% CI 1.78-10), Ki 67 index ≥ 15% (OR 3.64, 95% CI 1.36-9.76), and elevated LDH level (OR 8.6, 95% CI 3.2-22.8) were all associated with positive FDG avidity. In a multivariate linear regression model, a combination of advanced clinical stage, specific disease subtypes, LDH level, and Ki 67 index predicted the value of SUVmax (P value < 0.001; adjusted R² = 33.8%) and SUVmax/SUVliver (P value < 0.001; adjusted R² = 27%). Baseline FDG avidity was associated to PFS and OS only in univariate analyses.

CONCLUSIONS

In this retrospective cohort study, we present prediction models for positive FDG uptake and SUVmax in MZL patients. These models aim to help clinicians choose patients suitable for incorporation of FDG-PET/CT for staging and monitoring disease and reduce the costs of redundant tests.

New standards for phantom image quality and SUV harmonization range for multicenter oncology PET studies

Not only visual interpretation for lesion detection, staging, and characterization, but also quantitative treatment response assessment are key roles for ¹⁸F-FDG PET in oncology. In multicenter oncology PET studies, image quality standardization and SUV harmonization are essential to obtain reliable study outcomes. Standards for image quality and SUV harmonization range should be regularly updated according to progress in scanner performance. Accordingly, the first aim of this study was to propose new image quality reference levels to ensure small lesion detectability. The second aim was to propose a new SUV harmonization range and an image noise criterion to minimize the inter-scanner and intra-scanner SUV variabilities. We collected a total of 37 patterns of images from 23 recent PET/CT scanner models using the NEMA NU2 image quality phantom. PET images with various acquisition durations of 30-300 s and 1800 s were analyzed visually and quantitatively to derive visual detectability scores of the 10-mm-diameter hot sphere, noise-equivalent count (NEC_phantom), 10-mm sphere contrast (Q_H,10 mm), background variability (N_10 mm), contrast-to-noise ratio (Q_H,10 mm/N_10 mm), image noise level (CV_BG), and SUVmax and SUVpeak for hot spheres (10-37 mm diameters). We calculated a reference level for each image quality metric, so that the 10-mm sphere can be visually detected. The SUV harmonization range and the image noise criterion were proposed with consideration of overshoot due to point-spread function (PSF) reconstruction. We proposed image quality reference levels as follows: Q_H,10 mm/N_10 mm ≥ 2.5 and CV_BG ≤ 14.1%. The 10th-90th percentiles in the SUV distributions were defined as the new SUV harmonization range. CV_BG ≤ 10% was proposed as the image noise criterion, because the intra-scanner SUV variability significantly depended on CV_BG. We proposed new image quality reference levels to ensure small lesion detectability. A new SUV harmonization range (in which PSF reconstruction is applicable) and the image noise criterion were also proposed for minimizing the SUV variabilities. Our proposed new standards will facilitate image quality standardization and SUV harmonization of multicenter oncology PET studies. The reliability of multicenter oncology PET studies will be improved by satisfying the new standards.

[PET Research in Clinical Oncology]

Positron emission tomography (PET) in nuclear medicine is especially used for diagnosis in clinical oncology, and PET/CT examination using ¹⁸F-FDG is very useful for staging and therapy evaluation of cancer. The excellent property of PET diagnosis is that the functional information of cells can be evaluated quantitatively, but it also has the problem that its quantitative value fluctuates depending on image reconstruction conditions and body movements/respiratory movements. In this paper, we summarize the PET research that has been conducted so far in clinical oncology, and also introduce our researches for improve the quantitativeness.

68Ga-DOTATATE PET/CT: The Optimum Standardized Uptake Value (SUV) Internal Reference

RATIONALE AND OBJECTIVES

Standardized Uptake Value (SUV) is an important semiquantitative measurement used in the clinical and research domains to assess radiopharmaceutical concentration in tumors versus normal organs, but is susceptible to many factors beyond the tumor biological environment. So, the aim of this study is to identify the optimum internal reference among organs with physiological uptake in ⁶⁸Ga-DOTATATE PET/CT (DOTA PET/CT) scans.

MATERIALS AND METHODS

This HIPAA-compliant, IRB-approved study with waiver of consent included retrospective imaging review of 180 consecutive patients with neuroendocrine tumors presenting for DOTA PET/CT image acquisition: Ga-⁶⁸ DOTATATE dose was reported as (0.054 mCi/Kg) scans between September 2018 and May 2019. Mean value of body weight normalized SUV (SUV_bw) and lean body mass normalized SUV (SUL) of liver and spleen were measured. Information about the patients and scan characteristics were collected. The paired Grambsch test was used to compare variance among the measured SUVs. Spearman's rank correlation coefficient was used to assess correlation between SUVs and potential patient- and scan-specific confounding factors.

RESULTS

Variance of SUL was significantly lower than variance of SUV_bw in both liver and spleen (p-value < 0.0001). Variances of liver SUV_bw and SUL were significantly lower than the corresponding spleen SUVs. Liver SUL showed the lowest variance (3.69% ± 1.25%) among all measured SUVs.

CONCLUSION

SUL is a more reproducible, less variable, and therefore more reliable quantitative measure in DOTA PET/CT scans, compared SUV_bw. Among the available organs with physiological uptake, liver SUL is the optimum internal reference given the liver's larger size and uniform SUL values resulting in lower variability and better reproducibility.

Correlation of the quantitative methods for the measurement of bone uptake and plasma clearance of 18F-NaF using positron emission tomography. Systematic review and meta-analysis

PURPOSE

¹⁸F-NaF PET is valuable for detecting bone metabolism through osteoblastic activity in the assessment of bone disease. Hawkins, Patlak, and standardised uptake value (SUV) are the most common quantitative measurements used to evaluate bone metabolism. This systematic review evaluates the correlation between quantitative positron emission tomography (PET) methods and to compare their precision.

METHODS

A systematic search in Medline, PubMed, SCOPUS, and Web of Science was undertaken to find relevant papers published from 2000. All studies with human adults undergoing ¹⁸F-NaF PET, PET/CT, or PET/MRI were included except for subjects diagnosed with non-diffuse metabolic bone disease or malignancy. Quality Assessment Tool for Studies of Diverse Designs (QATSDD) was used to assess risk of bias. A qualitative review and meta-analysis using Hedges random-effect model was used producing summary size effects of the correlation between methods in healthy and unhealthy bone sites and assessing study heterogeneity.

RESULTS

228 healthy and unhealthy participants were included across 12 studies resulted from the systematic search. One-third of studies had a moderate quality percentage while the rest had relatively high quality. The pooled correlation coefficient in meta-analysis showed a high correlation of more than 0.88 (0.71-1.05. 95 %CI) between SUV and Hawkins and more than 0.96 (0.88-1.03. 95 %CI) between Patlak and Hawkins within all subgroups, suggesting all methods yield similar results in healthy and unhealthy bone sites. SUV has the lowest precision error followed by Patlak while Hawkins method showed the highest precision error.

CONCLUSION

Patlak is the best within research and SUV is better within clinical practice.

Semi-Quantitative and Quantitative [18F]FDG-PET/CT Indices for Diagnosing Large Vessel Vasculitis: A Critical Review

To confirm the diagnosis of large vessel vasculitis (LVV) with high accuracy, one of the recommended imaging techniques is [¹⁸F]Fluoro-2-deoxy-d-glucose positron emission tomography with computed tomography ([¹⁸F]FDG-PET/CT). Visual assessment of [¹⁸F]FDG uptake in the arterial wall compared to liver uptake is the mainstay for diagnosing LVV in routine clinical practice. To date, there is no consensus on the preferred semi-quantitative or quantitative parameter for diagnosing LVV. The aim of this review is to critically update the knowledge on the available evidence of semi-quantitative and quantitative [¹⁸F]FDG uptake parameters for diagnosing LVV and to provide future directions for methodological standardization and research.

Usefulness of quantitative bone SPECT/CT for medication-related osteonecrosis of the jaw in clinical settings

OBJECTIVE

This study was conducted to investigate the clinical utility of quantitative bone single-photon computed tomography-computed tomography (SPECT/CT) for detection and classification for medication-related osteonecrosis of the jaw (MRONJ).

MATERIALS AND METHODS

Fifty-nine patients (69 lesions) clinically diagnosed as MRONJ by four specialists of Japanese Society of Oral Surgery according to the AAOMS diagnostic criteria and who underwent bone SPECT/CT were enrolled. One reader determined standard uptake values (SUVs), including maximum (SUVmax), peak (SUVpeak), and mean (SUVmean), as well as metabolic bone volume (MBV), representing total volume above threshold, and total bone uptake (TBU), calculated as MBV × SUVmean, using the GI-BONE software package. One-way repeated-measures analysis of variance and subsequent post hoc analysis were employed to compare quantitative values between clinical stages. To check reproducibility of values, another reader calculated these quantitative values.

RESULTS

Mean SUVmax values for stage 0 (n = 21), 1 (n = 13), 2 (n = 25), and 3 (n = 10) were 5.82 ± 3.20, 5.46 ± 3.79, 8.16 ± 3.93, and 10.57 ± 8.43, respectively, while values for MBV were 9.52 ± 6.33, 11.36 ± 7.32, 12.4 ± 8.21, and 17.84 ± 16.94, respectively, and for TBU were 40.60 ± 46.97, 53.70 ± 77.26, 62.37 ± 42.91, and 102.01 ± 74.52, respectively. There were significant differences for SUVmax, SUVpeak, and SUVmean between clinical stages (p = 0.024, p = 0.027, p = 0.039, respectively). Subsequent post hoc analysis showed that SUVmax and SUVpeak of stage 3 were significantly higher than those of stage 0 (p = 0.046, 0.045, respectively). MBV and TBU showed a tendency to increase with increased stage, though differences between stages were not significant (p = 0.15, p = 0.053, respectively). Little differences of mean SUVmax, SUVpeak, SUVmean, MBV, and TBU between two readers were observed (- 3.10%, - 0.26%, - 4.24%%, 0.69%, and - 3.42%, respectively). The intraclass correlation coefficients (ICCs) of SUVmax, SUVpeak, SUVmean, MBV, and TBU were 0.985, 0.990, 0.980, 0.994, and 0.994, respectively (almost perfect for all values).

CONCLUSION

As objective and reliable indicators, SUVmax and SUVpeak derived from quantitative bone SPECT/CT results are useful for detection of early status disease, as well as staging in MRONJ patients.

Nighttime pedestrian fatalities: A comprehensive examination of infrastructure, user, vehicle, and situational factors

INTRODUCTION

Pedestrian fatalities in the United States increased 45.5% between 2009 and 2017. More than 85% of those additional pedestrian fatalities occurred at night.

METHOD

We examine Fatality Analysis Reporting System (FARS) data for fatal pedestrian crashes that occurred in the dark between 2002 and 2017. Within-variable and before/after examinations of crashes in terms of infrastructure, user, vehicle, and situational characteristics are performed with one-way analysis of variance (ANOVA) and two-sample t-tests. We model changes in crash characteristic proportions between 2002-2009 and 2010-2017 using linear regressions and test for autocorrelation with Breusch-Godfrey tests.

RESULTS

The increase in fatal nighttime pedestrian crashes is most strongly correlated with infrastructure factors: non-intersection unmarked locations (saw 80.8% of additional fatalities); 40-45 mph roads (54.6%); five-lane roads (40.7%); urban (99.7%); and arterials (81.1%). In addition, SUVs were involved in 39.7% of additional fatalities, overrepresenting their share of the fleet. Increased pedestrian alcohol and drug involvement warrant further investigation. The age of pedestrians killed increased more (18.1%) than the national average (3.2%).

CONCLUSIONS

By identifying factors related to the increase in nighttime pedestrian fatalities, this work constitutes a vital first step in making our streets safer for pedestrians. Practical Applications: More research is needed to understand the efficacy of different solutions, but this paper provides guidance for such future research. Engineering solutions such as road diets or traffic calming may be used to improve identified infrastructure issues by reducing vehicle speeds and road widths. Rethinking vehicle design, especially high front profiles, may improve vehicle issues. However, the problems giving rise to these pedestrian fatalities are likely a result of not only engineering issues but also interrelated social and political factors. Solutions may be correspondingly comprehensive, employing non-linear, systems-based approaches such as Safe Systems.

Receptor depletion and recovery in small-intestinal neuroendocrine tumors and normal tissues after administration of a single intravenous dose of octreotide measured by 68Ga-DOTATOC PET/CT

BACKGROUND

Low-grade neuroendocrine tumors (NETs) are characterized by an abundance of somatostatin receptors (SSTR) that can be targeted with somatostatin analogs (SSA). When activated with a single dose of SSA, the receptor-ligand complex is internalized, and the receptor is by default recycled within 24 h. Ongoing medication with long-acting SSAs at ⁶⁸Ga-DOTA-SSA-PET has been shown to increase the tumor-to-normal organ contrast. This study was performed to investigate the time-dependent extended effect (7 h) of a single intravenous dose of 400 µg short-acting octreotide on the tumor versus normal tissue uptake of ⁶⁸Ga-DOTATOC.

METHODS

Patients with small-intestinal NETs received a single intravenous dose of 400 µg octreotide and underwent dynamic abdominal ⁶⁸Ga-DOTATOC-PET/CT at three sessions (0, 3 and 6 h) plus static whole-body (WB) PET/CT (1, 4 and 7 h), starting each PET/CT session by administering 167 ± 21 MBq, 23.5 ± 4.2 µg (mean ± SD, n = 12) of ⁶⁸Ga-DOTATOC. A previously acquired clinical whole-body ⁶⁸Ga-DOTATOC scan was used as baseline. SUV and net uptake rate K_i were calculated in tumors, and SUV in healthy organs.

RESULTS

Tumor SUV decreased significantly from baseline to 1 h post-injection but subsequently increased over time and became similar to baseline at 4 h and 7 h. The tumor net uptake rate, K_i, similarly increased significantly over time and showed a linear correlation both with SUV and tumor-to-blood ratio. By contrast, the uptake in liver, spleen and pancreas remained significantly below baseline levels also at 7 h and the receptor turn-over in tumors thus exceeded that in the normal tissue, with restitution of tumor ⁶⁸Ga-DOTATOC uptake mainly completed at 7 h. These results however differed depending on tumor size, with significant increases in K_i and SUV between the 1st and 2nd PET, in large tumors (≥ 4 mL) but not in small (> 1 to  < 4 mL) tumors.

CONCLUSION

SSTR recycling is faster in small-intestinal NETs than in liver, spleen and pancreas. This opens the possibility to protect normal tissues during PRRT by administering a single dose of cold peptide hours before peptide receptor radionuclide therapy (PRRT), and most likely additionally improve the availability and uptake of the therapeutic preparation in the tumors.

68Ga-FAPI-PET/CT in patients with various gynecological malignancies

PURPOSE

68Ga-FAPI (fibroblast activation protein inhibitor) is a novel and highly promising radiotracer for PET/CT imaging. The aim of this retrospective analysis is to explore the potential of FAPI-PET/CT in gynecological malignancies. We assessed biodistribution, tumor uptake, and the influence of pre- or postmenopausal status on tracer accumulation in hormone-sensitive organs. Furthermore, a comparison with the current standard oncological tracer 18F-FDG was performed in selected cases.

PATIENTS AND METHODS

A total of 31 patients (median age 59.5) from two centers with several gynecological tumors (breast cancer; ovarian cancer; cervical cancer; endometrial cancer; leiomyosarcoma of the uterus; tubal cancer) underwent 68Ga-FAPI-PET/CT. Out of 31 patients, 10 received an additional 18F-FDG scan within a median time interval of 12.5 days (range 1-76). Tracer uptake was quantified by standardized uptake values (SUV)max and (SUV)mean, and tumor-to-background ratio (TBR) was calculated (SUVmax tumor/ SUVmean organ). Moreover, a second cohort of 167 female patients with different malignancies was analyzed regarding their FAPI uptake in normal hormone-responsive organs: endometrium (n = 128), ovary (n = 64), and breast (n = 147). These patients were categorized by age as premenopausal (<35 years; n = 12), postmenopausal (>65 years; n = 68), and unknown menstrual status (35-65 years; n = 87), followed by an analysis of FAPI uptake of the pre- and postmenopausal group.

RESULTS

In 8 out of 31 patients, the primary tumor was present, and all 31 patients showed lesions suspicious for metastasis (n = 81) demonstrating a high mean SUVmax in both the primary (SUVmax 11.6) and metastatic lesions (SUVmax 9.7). TBR was significantly higher in 68Ga-FAPI compared to 18F-FDG for distant metastases (13.0 vs. 5.7; p = 0.047) and by trend for regional lymph node metastases (31.9 vs 27.3; p = 0.6). Biodistribution of 68Ga-FAPI-PET/CT presented significantly lower uptake or no significant differences in 15 out of 16 organs, compared to 18F-FDG-PET/CT. The highest uptake of all primary lesions was obtained in endometrial carcinomas (mean SUVmax 18.4), followed by cervical carcinomas (mean SUVmax 15.22). In the second cohort, uptake in premenopausal patients differed significantly from postmenopausal patients in endometrium (11.7 vs 3.9; p < 0.0001) and breast (1.8 vs 1.0; p = 0.004), whereas no significant difference concerning ovaries (2.8 vs 1.6; p = 0.141) was observed.

CONCLUSION

Due to high tracer uptake resulting in sharp contrasts in primary and metastatic lesions and higher TBRs than 18F-FDG-PET/CT, 68Ga-FAPI-PET/CT presents a promising imaging method for staging and follow-up of gynecological tumors. The presence or absence of the menstrual cycle seems to correlate with FAPI accumulation in the normal endometrium and breast. This first investigation of FAP ligands in gynecological tumor entities supports clinical application and further research in this field.

Is SUV Corrected for Lean Body Mass Superior to SUV of Body Weight in 68Ga-PSMA PET/CT?

Objectives:

This study aimed to investigate the relationship between the standard uptake value (SUV) of body weight and SUV corrected for lean body mass (SUL) parameters obtained from the prostate gland in gallium-68 (⁶⁸Ga)-prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET/CT) with Gleason grade (GG) groups, D’Amico risk groups, and presence of metastases.

Methods:

Patients with prostate adenocarcinoma who underwent ⁶⁸Ga-PSMA PET/CT for staging at our center between February 2017 and October 2018 were evaluated retrospectively. Maximum SUV (SUV_max), SUV_peak, SUL_max, SUL_peak, SUV_mean, and SUL_mean values of the prostate tumor were obtained. The difference in these values between GG groups (≥3, <3) and D’Amico risk (low-moderate/high) groups was evaluated with the Mann-Whitney U test. The area under the curve values of SUV and SUL parameters were compared. In addition, SUV_mean and SUL_mean values were obtained from the right liver lobe, and their correlation with body weight was evaluated.

Results:

A total of 79 patients were included in the study. Significant differences were found in the prostate SUV_max, SUL_max, SUV_peak, SUL_peak, SUV_mean, and SUL_mean values between the GG (≥3 and <3) groups and between D’Amico risk (low-moderate and high) groups. However, no significant difference was found in the discriminative power of any SUV or SUL parameter when compared with each other. A significant difference in any SUV and SUL parameters was found in patients with and without metastasis. Neither liver SUV_mean value nor SUL_mean value correlated with the body weight.

Conclusion:

The superiority of SUL values obtained from ⁶⁸Ga-PSMA PET to SUV was not determined in our study. SUV parameters can also be used for quantitative analysis in ⁶⁸Ga-PSMA PET.

Changes of [18F]FDG-PET/CT quantitative parameters in tumor lesions by the Bayesian penalized-likelihood PET reconstruction algorithm and its influencing factors

Background

To compare the changes in quantitative parameters and the size and degree of ¹⁸F-fluorodeoxyglucose ([¹⁸F]FDG) uptake of malignant tumor lesions between Bayesian penalized-likelihood (BPL) and non-BPL reconstruction algorithms.

Methods

Positron emission tomography/computed tomography images of 86 malignant tumor lesions were reconstructed using the algorithms of ordered subset expectation maximization (OSEM), OSEM + time of flight (TOF), OSEM + TOF + point spread function (PSF), and BPL. [¹⁸F]FDG parameters of maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and signal-to-background ratio (SBR) of these lesions were measured. Quantitative parameters between the different reconstruction algorithms were compared, and correlations between parameter variation and lesion size or the degree of [¹⁸F]FDG uptake were analyzed.

Results

After BPL reconstruction, SUVmax, SUVmean, and SBR were significantly increased, MTV was significantly decreased. The difference values of %ΔSUVmax, %ΔSUVmean, %ΔSBR, and the absolute value of %ΔMTV between BPL and OSEM + TOF were 40.00%, 38.50%, 33.60%, and 33.20%, respectively, which were significantly higher than those between BPL and OSEM + TOF + PSF. Similar results were observed in the comparison of OSEM and OSEM + TOF + PSF with BPL. The %ΔSUVmax, %ΔSUVmean, and %ΔSBR were all significantly negatively correlated with the size and degree of [¹⁸F]FDG uptake in the lesions, whereas significant positive correlations were observed for %ΔMTV and %ΔTLG.

Conclusion

The BPL reconstruction algorithm significantly increased SUVmax, SUVmean, and SBR and decreased MTV of tumor lesions, especially in small or relatively hypometabolic lesions.

Clinical value of baseline 18F-FDG PET/CT in soft tissue sarcomas

Background

The use of ¹⁸F-FDG Positron emission tomography/Computed tomography (PET/CT) in the initial staging of many cancers is clearly established. Most soft tissue sarcoma (STS) has a high affinity for ¹⁸F-FDG, which is why ¹⁸F-FDG PET/CT has been proposed as a non-invasive method, useful in diagnosis and follow-up. The standardized uptake value values (SUV), the volume-based metabolic parameters MTV (metabolic tumor volume), and TLG (total lesion glycolysis) determine tumor viability and provide its total volume and the total activity of metabolically active tumor cells. The histological grade is the most important predictor of metastases and mortality associated with STS, and a significant relationship between the metabolic parameters of ¹⁸F-FDG PET/CT and the histological grade has been described.

Methods

A retrospective study was conducted on STS patients, who had histological grade according to the FNCLCC (Fédération Nationale des Centres de Lutte Contre Le Cancer) criteria, as well as a baseline PET/CT. SUV (SUV_max, SUV_mean, and SUV_peak), MTV, and TLG were quantified. A T-student test was performed to establish the relationship between the metabolic biomarkers and the histological grade. Their usefulness as predictors of the histological grade was verified using receiver operator characteristic (ROC) curves. A survival function study was performed using the Kaplan–Meier method. To assess the prognostic utility of the metabolic biomarkers we use the Log-Rank method.

Results

The SUV values were useful to discriminate high-grade STS. We found a significant relationship between the histological grade and the SUV values. SUV_max, SUV_peak, MTV, and TLG were predictors of overall survival (OS). There were no significant differences in the OS for the SUV_mean, or in the disease-free survival (DFS) for SUV_max, SUV_mean, SUV_peak, MTV, and TLG.

Conclusions

The SUV_max, SUV_mean, and SUV_peak values correlate with the HG and are useful to discriminate high-grade from low-grade STS. Patients with high SUV_max, SUV_peak, MTV, and TLG have a significantly lower OS.

Data-driven gated PET/CT: implications for lesion segmentation and quantitation

Background

Data-driven gating (DDG) can improve PET quantitation and alleviate many issues with patient motion. However, misregistration between DDG-PET and CT may occur due to the distinct temporal resolutions of PET and CT and can be mitigated by DDG-CT. Here, the effects of misregistration and respiratory motion on PET quantitation and lesion segmentation were assessed with a new DDG-PET/CT method.

Methods

A low-dose cine-CT was acquired in misregistered regions to enable both average CT (ACT) and DDG-CT. The following were compared: (1) baseline PET/CT, (2) PET/ACT (attenuation correction, AC = ACT), (3) DDG-PET (AC = helical CT), and (4) DDG-PET/CT (AC = DDG-CT). For DDG-PET, end-expiration (EE) data were derived from 50% of the total PET data at 30% from end-inspiration. For DDG-CT, EE phase CT data were extracted from cine-CT data by lung Hounsfield unit (HU) value and body contour. A total of 91 lesions from 16 consecutive patients were assessed for changes in standard uptake value (SUV), lesion glycolysis (LG), lesion volume, centroid-to-centroid distance (CCD), and DICE coefficients.

Results

Relative to baseline PET/CT, median changes in SUV_max ± σ for all 91 lesions were 20 ± 43%, 26 ± 23%, and 66 ± 66%, respectively, for PET/ACT, DDG-PET, and DDG-PET/CT. Median changes in lesion volume were 0 ± 58%, − 36 ± 26%, and − 26 ± 40%. LG for individual lesions increased for PET/ACT and decreased for DDG-PET, but was not different for DDG-PET/CT. Changes in mean HU from baseline PET/CT were dramatic for most lesions in both PET/ACT and DDG-PET/CT, especially for lesions with mean HU < 0 at baseline. CCD and DICE were both affected more by motion correction with DDG-PET than improved registration with ACT or DDG-CT.

Conclusion

As misregistration becomes more prominent, the impact of motion correction with DDG-PET is diminished. The potential benefits of DDG-PET toward accurate lesion segmentation and quantitation could only be fully realized when combined with DDG-CT. These results impress upon the necessity of ensuring both misregistration and motion correction are accounted for together to optimize the clinical utility of PET/CT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-021-00411-5.

When SUV Matters: FDG PET/CT at Baseline Correlates with Survival in Soft Tissue and Ewing Sarcoma

Introduction: The role of positron-emission tomography/computed-tomography (PET/CT) in the management of sarcomas and as a prognostic tool has been studied. However, it remains unclear which metric is the most useful. We aimed to investigate if volume-based PET metrics (Tumor volume (TV) and total lesions glycolysis (TLG)) are superior to maximal standardized uptake value (SUVmax) and other metrics in predicting survival of patients with soft tissue and bone sarcomas. Materials and Methods: In this retrospective cohort study, we screened over 52′000 PET/CT scans to identify patients diagnosed with either soft tissue, bone or Ewing sarcoma and had a staging scan at our institution before initial therapy. We used a Wilcoxon signed-rank to assess which PET/CT metric was associated with survival in different patient subgroups. Receiver-Operating-Characteristic curve analysis was used to calculate cutoff values. Results: We identified a total of 88 patients with soft tissue (51), bone (26) or Ewing (11) sarcoma. Median age at presentation was 40 years (Range: 9–86 years). High SUVmax was most significantly associated with short survival (defined as <24 months) in soft tissue sarcoma (with a median and range of SUVmax 12.5 (8.8–16.0) in short (n = 18) and 5.5 (3.3–7.2) in long survival (≥24 months) (n = 31), with (p = 0.001). Similar results were seen in Ewing sarcoma (with a median and range of SUVmax 12.1 (7.6–14.7) in short (n = 6) and 3.7 (3.5–5.5) in long survival (n = 5), with (p = 0.017). However, no PET-specific metric but tumor-volume was significantly associated (p = 0.035) with survival in primary bone sarcomas (with a median and range of 217 cm³ (186–349) in short survival (n = 4) and 60 cm³ (22–104) in long survival (n = 19), with (p = 0.035). TLG was significantly inversely associated with long survival only in Ewing sarcoma (p = 0.03). Discussion: Our analysis shows that the outcome of soft tissue, bone and Ewing sarcomas is associated with different PET/CT metrics. We could not confirm the previously suggested superiority of volume-based metrics in soft tissue sarcomas, for which we found SUVmax to remain the best prognostic factor. However, bone sarcomas should probably be evaluated with tumor volume rather than FDG PET activity.

Baseline 18F-FDG PET/CT quantitative parameters as prognostic factors in esophageal squamous cell cancer

AIM

To determine the utility of [¹⁸F]FDG PET/CT quantitative parameters as prognostic factors for the response to neoadjuvant treatment, progression-free survival (PFS) and cancer-specific survival (CSS) in patients with esophageal squamous cell carcinoma (SCC).

MATERIAL AND METHODS

Thirty patients (29 men) diagnosed with SCC were retrospectively evaluated over a 6-year interval. Metabolic parameters were determined: maximum SUV (SUVmax), mean SUV (SUVmed), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) from baseline PET/CT study. After treatment with chemotherapy and/or radiotherapy, response to treatment and patient survival were assessed. The comparison of parameters between groups of responders and non-responders was carried out using a Mann-Whitney U test ROC curves and the Kaplan-Meier method were used for analysis of prognostic factors and survival curves.

RESULTS

The average follow-up was 22.4 months, with 22 recurrence-progressions and 25 deaths. Significant differences were demonstrated between responders and non-responders with respect to tumor size, MTV and TLG. Survival analysis found significant differences for SCE and CSS depending on these three parameters.

CONCLUSION

Metabolic parameters MTV and TLG, and tumor size were prognostic factors for neoadjuvant treatment response, PFS, and CSS in patients diagnosed with SCC. Neither SUVmax nor SUVmed were predictive for any of the evaluation criteria. Results could help to personalize patient treatment.

Small target repeatability of 68Ga and 18F: effects of target concentration and imaging time on SUV measurements in clinically relevant phantoms

Quantification of tumor uptake using PET imaging is important for the evaluation of therapy response. For ¹⁸F FDG PET scans, a change in uptake of 25% is commonly considered significant. For scans using novel radiopharmaceuticals, the threshold of significance is unclear. Factors including imaging time, tumor size, activity concentration, and radiopharmaceutical may affect the repeatablity of uptake metrics. This work evaluates the effect of these parameters on the repeatablity of maximum SUV (SUV_max) and mean SUV (SUV_mean) in phantoms using ¹⁸F and ⁶⁸Ga. An Esser PET phantom (Data Spectrum, Durham NC) was scanned on a Biograph Horizon PET/CT scanner (Siemens Medical Solutions, Malvern PA) using ¹⁸F and ⁶⁸Ga. Data were acquired for 5 minutes with reconstructions between 0.5-5 minutes. The background activity mimicked clinical scans with target-to-background (T/B) ratios from 1.7-19.8. The SUV_max and SUV_mean were measured for 5 slices. The mean, standard deviation, and coefficient of variation (COV) were calculated. The effects of radionuclide, imaging time, activity concentration, and target size on COV were evaluated using multivariate gamma regressions. COV for ⁶⁸Ga was 40% higher and 54% higher on average than for ¹⁸F for SUV_max and SUV_mean, respectively. Decreased lesion size, imaging time, and activity concentration were significantly associated with increased COV for both metrics (P < 0.001). COV was substantially reduced at high T/B for ⁶⁸Ga. At the highest T/B the COV for SUV_max and SUV_mean was within the typical range seen for ¹⁸F. COV is relatively high for small targets (8 mm) but is dramatically reduced with high radiotracer uptake.

18F-FDG PET/CT for monitoring anti-PD-1 therapy in patients with non-small cell lung cancer using SUV harmonization of results obtained with various types of PET/CT scanners used at different centers

OBJECTIVE

The prognostic value of treatment response in patients with non-small cell lung cancer (NSCLC) treated with immune-checkpoint inhibitors (ICIs) shown by ¹⁸F-fludeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) results obtained with multiple types of PET scanners using standardized uptake value (SUV) harmonization was evaluated.

METHODS

Fifty-eight patients treated with ICIs who underwent ¹⁸F-FDG PET/CT examinations with nine types of PET scanners at six hospitals were enrolled. SUV harmonization of multiple PET scanner results was performed using the dedicated software packages "RAVAT" and "RC Tool for Harmonization". Tumor response was assessed by change in sum of harmonized SUVmax, according to the European Organization for Research and Treatment of Cancer (EORTC5) or the SUV of up to five lesions normalized to lean body mass, according to the PET Response Criteria in Solid Tumors (PERCIST5) and immunotherapy-modified PERCIST (imPERCIST5) criteria. The correlation between tumor response according to those three definitions and overall survival (OS) was evaluated and compared to known prognostic factors.

RESULTS

One-year OS in responders and non-responders for harmonized EROTC5 was 86 and 32%, for harmonized PERCIST5 was 86 and 32%, and for harmonized imPERCIST5 was 80 and 30%, respectively (each p = 0.001). Univariate analysis showed that all response criteria remained as prognostic factors. However, there was an overlap for the categories stable metabolic disease (SMD) and progression metabolic disease (PMD) in survival curves using the PET treatment response criteria.

CONCLUSION

In patients with NSCLC treated with ICIs, tumor response based on the harmonized response criteria was associated with OS. PET response criteria using harmonized metabolic parameters may be difficult to routinely employ in daily practice due to overlapping SMD and PMD, although may have a supporting role for determining prognosis.