Comparison of three diagnostic strategies for suspicion of pulmonary embolism: planar ventilation-perfusion scan (V/Q), CT pulmonary angiography (CTPA) and single photon emission CT ventilation-perfusion scan (SPECT V/Q): a protocol of a randomised controlled trial

INTRODUCTION

Pulmonary embolism (PE) is a challenge to diagnose and when missed, exposes patients to potentially fatal recurrent events. Beyond CT pulmonary angiography (CTPA) and planar ventilation/perfusion (V/Q) scan, single photon emission CT (SPECT) V/Q emerged a new diagnostic modality of scintigraphic acquisition that has been reported to improve diagnostic performances. To date, no management outcome study or randomised trial evaluated an algorithm based on SPECT V/Q for PE diagnosis. We present the design of a randomised multicentre, international management study comparing SPECT V/Q with validated strategies.

MATERIAL AND METHODS

We will include a total of 3672 patients with suspected PE requiring chest imaging, randomised into three different groups, each using a different diagnostic strategy based on SPECT V/Q, CTPA and planar V/Q scan. Randomisation will be unbalanced (2:1:1), with twice as many patients in SPECT V/Q arm (n=1836) as in CTPA and planar V/Q arms (n=918 in each). Our primary objective will be to determine whether a diagnostic strategy based on SPECT V/Q is non-inferior to previously validated strategies in terms of diagnostic exclusion safety as assessed by the 3-month risk of thromboembolism in patients with a negative diagnostic workup. Secondary outcomes will be the proportion of patients diagnosed with PE in each arm, patients requiring additional tests, the incidence of major and clinically relevant non-major bleeding and the incidence and cause of death in each arm.

ETHICS AND DISSEMINATION

This trial is funded by a grant from Brest University Hospital and by INVENT. The study protocol was approved by Biomedical Research Ethics Committee. The investigator or delegate will obtain signed informed consent from all patients prior to inclusion in the trial. Our results will inform future clinical practice guidelines and solve the current discrepancy between nuclear medicine guidelines and clinical scientific society guidelines.

TRIAL REGISTRATION NUMBER

NCT02983760.

[18F]DCFPyL PET/CT versus [18F]fluoromethylcholine PET/CT in Biochemical Recurrence of Prostate Cancer (PYTHON): a prospective, open label, cross-over, comparative study

PURPOSE

Primary objective was to compare the per-patient detection rates (DR) of [18F]DCFPyL versus [18F]fluoromethylcholine positron emission tomography/computed tomography (PET/CT), in patients with first prostate cancer (PCa) biochemical recurrence (BCR). Secondary endpoints included safety and impact on patient management (PM).

METHODS

This was a prospective, open label, cross-over, comparative study with randomized treatment administration of [18F]DCFPyL (investigational medicinal product) or [18F]fluoromethylcholine (comparator). Men with rising prostate-specific antigen (PSA) after initial curative therapy were enrolled. [18F]DCFPyL and [18F]fluoromethylcholine PET/CTs were performed within a maximum time interval of 12 days. DR was defined as the percentage of positive PET/CT scans identified by 3 central imaging readers. PM was assessed by comparing the proposed pre-PET/CT treatment with the local treatment", defined after considering both PET/CTs.

RESULTS

A total of 205 patients with first BCR after radical prostatectomy (73%; median PSA = 0.46 ng/ml [CI 0.16;27.0]) or radiation therapy (27%; median PSA = 4.23 ng/ml [CI 1.4;98.6]) underwent [18F]DCFPyL- and/or [18F]fluoromethylcholine -PET/CTs, between July and December 2020, at 22 European sites. 201 patients completed the study. The per-patient DR was significantly higher for [18F]DCFPyL- compared to [18F]fluoromethylcholine -PET/CTs (58% (117/201 patients) vs. 40% (81/201 patients), p < 0.0001). DR increased with higher PSA values for both tracers (PSA ≤ 0.5 ng/ml: 26/74 (35%) vs. 22/74 (30%); PSA 0.5 to ≤ 1.0 ng/ml: 17/31 (55%) vs. 10/31 (32%); PSA 1.01 to < 2.0 ng/ml: 13/19 (68%) vs. 6/19 (32%);PSA > 2.0: 50/57 (88%) vs. 39/57 (68%) for [18F]DCFPyL- and [18F]fluoromethylcholine -PET/CT, respectively). [18F]DCFPyL PET/CT had an impact on PM in 44% (90/204) of patients versus 29% (58/202) for [18F]fluoromethylcholine. Overall, no drug-related nor serious adverse events were observed.

CONCLUSIONS

The primary endpoint of this study was achieved, confirming a significantly higher detection rate for [18F]DCFPyL compared to [18F]fluoromethylcholine, in men with first BCR of PCa, across a wide PSA range. [18F]DCFPyL was safe and well tolerated.

Residual pulmonary vascular obstruction and recurrence after acute pulmonary embolism: a systematic review and meta-analysis of individual participant data

We aimed to assess the relationship between residual pulmonary vascular obstruction (RPVO) on planar lung scan after completion of at least 3 months of anticoagulant therapy for acute pulmonary embolism (PE) and the risk of recurrent venous thromboembolism (VTE) or death due to PE one year after treatment discontinuation. The systematic review was registered with the International Prospective Registry of Systematic Reviews (PROSPERO: CRD42017081080). The primary outcome measure was to generate a pooled estimate of the rate of recurrent VTE at one year in patient with RPVO diagnosed on planar lung scan after discontinuation of at least 3 months of anticoagulant treatment for an acute PE. Individual data were obtained for 809 patients. RPVO (ie, obstruction >0%) was found in 407 patients (50.3%) after a median of 6.6 months of anticoagulant therapy for a first acute PE. Recurrent VTE or death due to PE occurred in 114 patients (14.1%), for an annual risk of 6.4% (95% confidence interval, 4.7%-8.6%). Out of the 114 recurrent events, 63 occurred within one year after discontinuation of anticoagulant therapy corresponding to a risk of 8.1% (6.4%-9.8%) at 1 year. The risk of recurrent VTE at one year was 5.8% (4.4-7.2) in participants with RPVO <5%, vs 11.7% (9.5-13.8) in participants with RPVO ≥5%. RPVO is a significant predictor of the risk of recurrent venous thromboembolism. However, the risk of recurrent events remains too high in patients without residual perfusion defect for it to be used as a stand-alone test to decide on anticoagulation discontinuation.

Long-term memory and synapse-like dynamics in two-dimensional nanofluidic channels

Fine-tuned ion transport across nanoscale pores is key to many biological processes, including neurotransmission. Recent advances have enabled the confinement of water and ions to two dimensions, unveiling transport properties inaccessible at larger scales and triggering hopes of reproducing the ionic machinery of biological systems. Here we report experiments demonstrating the emergence of memory in the transport of aqueous electrolytes across (sub)nanoscale channels. We unveil two types of nanofluidic memristors depending on channel material and confinement, with memory ranging from minutes to hours. We explain how large time scales could emerge from interfacial processes such as ionic self-assembly or surface adsorption. Such behavior allowed us to implement Hebbian learning with nanofluidic systems. This result lays the foundation for biomimetic computations on aqueous electrolytic chips.

PSMA-11 PET/CT for Detection of Recurrent Prostate Cancer in Patients With Negative Choline PET/CT

INTRODUCTION

Prostate adenocarcinoma (CaP) is the leading cancer in men. After curative treatment, from 27% to 53% of patients will experience biochemical recurrence (BR). With the development of focal therapies, precise early identification of recurrence's sites is of utmost importance in order to deliver individualized treatment on positive lesions. The aim of this study was to assess the detection rate (DR) of ⁶⁸Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in selected patients with prostate cancer BR and recent negative ¹⁸F-choline PET/CT.

PATIENTS AND METHODS

We performed a retrospective analysis including all patients with CaP referred for BR with a negative ¹⁸F-choline PET/CT, and who underwent ⁶⁸Ga-PSMA-11 PET/CT between October, 2018 and December, 2019. The overall DR of ⁶⁸Ga-PSMA-11 PET/CT was calculated, and described according to BR characteristics especially PSA levels and velocity. Patients were followed up for at least 1 year. Patient management following ⁶⁸Ga-PSMA-11 PET/CT and PSA levels evolution after treatment were also recorded.

RESULTS

One hundred fifty-nine patients comprising 164 examinations were analyzed. The overall DR of ⁶⁸Ga-PSMA-11 PET/CT for BR was 65.9% (95CI, 58.6-73.1). The DR was 52.5% (95CI, 39.9-65.0), 70.6% (95CI, 55.3-85.9), 70.4% (95CI, 53.1-87.6), and 78.6% (95CI, 66.2-91.0) for PSA levels between 0.2 and 0.49 ng/mL, 0.5 to 0.99 ng/mL, 1 to 1.99 ng/mL and PSA ≥ 2 ng/mL, respectively. The DR was 70.7% (95CI, 59.0-82.4) with a PSA doubling time (PSA-DT) ≤6 months and 65.2% (95CI, 55.5-74.9) with a PSA-DT >6 months. Around 3/4 of patients (75.9%) with a positive ⁶⁸Ga-PSMA-11 PET/CT initiated treatment, including surgery (2.4%), stereotactic radiotherapy ± androgen deprivation therapy (ADT) (22%) or external conformational radiotherapy ± ADT (46.3%). Patient management changed in 43 cases (39.8%).

CONCLUSION

Our study confirmed the ability of ⁶⁸Ga-PSMA-11 PET/CT to detect occult biochemical recurrence, even in a selected population of CaP patients with negative ¹⁸F-choline PET/CT, even at low PSA levels.

Frequency and predictors for chronic thromboembolic pulmonary hypertension after a first unprovoked pulmonary embolism: Results from PADIS studies

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is a life-threatening complication of a pulmonary embolism (PE) whose incidence and predictors are not precisely determined.

OBJECTIVE

To determine the frequency and predictors for CTEPH after a first unprovoked PE.

PATIENTS/METHODS

In a randomized trial comparing an additional 18-month warfarin versus placebo in patients after a first unprovoked PE initially treated with vitamin K antagonist for 6 months, we applied recommended CTEPH screening strategies through an 8-year follow-up to determine cumulative incidence of CTEPH. CTEPH predictors were estimated using Cox models. Pulmonary vascular obstruction (PVO) and systolic pulmonary arterial pressure (sPAP) at PE diagnosis and 6 months were studied by receiver operating curves analysis. All CTEPH cases and whether they were incident or prevalent were adjudicated.

RESULTS

During a median follow-up of 8.7 years, nine CTEPH cases were diagnosed among 371 patients, with a cumulative incidence of 2.8% (95% confidence interval [CI] 0.95-4.64), and of 1.31% (95% CI 0.01-2.60) after exclusion of five cases adjudicated as prevalent. At PE diagnosis, PVO > 45% and sPAP > 56 mmHg were associated with CTEPH with a hazard ratio (HR) of 33.00 (95% CI 1.64-667.00, p = .02) and 12.50 (95% CI 2.10-74.80, p < .01), respectively. Age > 65 years, lupus anticoagulant antibodies and non-O blood groups were also predictive of CTEPH. PVO > 14% and sPAP > 34 mmHg at 6 months were associated with CTEPH (HR 63.90 [95% CI 3.11-1310.00, p < .01]and HR 17.2 [95% CI 2.75-108, p < .01]).

CONCLUSION

After a first unprovoked PE, CTEPH cumulative incidence was 2.8% during an 8-year follow-up. PVO and sPAP at PE diagnosis and at 6 months were the main predictors for CTEPH diagnosis.

Radiation exposure to nuclear medicine technologists performing a V/Q PET: Comparison with conventional V/Q scintigraphy, [18F]FDG PET and [68Ga]Ga DOTATOC PET procedures

Introduction

Ventilation/Perfusion (V/Q) PET/CT is an emerging imaging modality for regional lung function evaluation. The same carrier molecules as conventional V/Q scintigraphy are used but they are radiolabelled with gallium-68 (68Ga) instead of technetium-99m (99mTc). A recurrent concern regarding V/Q PET imaging is the radiation dose to the healthcare workers. The aim of this study was to evaluate the total effective dose and the finger dose received by the technologist when performing a V/Q PET procedure, and to compare them with the radiations doses received with conventional V/Q scintigraphy, FDG PET and Ga DOTATOC PET procedures.

Materials and methods

The whole body dose measurement was performed 10 times for each of the evaluated procedures using an electronic personal dosimeter (ED). For V/Q PET and V/Q scintigraphy procedures, ventilation and perfusion stages were separately evaluated. Internal exposure was measured for ventilation procedures. Finger dose measurements were performed 5 times for each of the PET procedures using Thermoluminescence (TL) pellets.

Results

The technologist effective dose when performing a V/Q PET procedure was 2.83 ± 0.67 μSv, as compared with 1.16 ± 0.34 μSv for conventional V/Q scintigraphy, 2.13 ± 0.77 μSv for [68Ga]Ga-DOTATOC, and 2.86 ± 1.79 μSv for FDG PET procedures, respectively. The finger dose for the V/Q PET procedure was similar to the dose for a [68Ga]Ga-DOTATOC scan (0.35 mSv and 0.32 mSv, respectively).

Conclusion

The technologist total effective dose for a V/Q PET procedure is ~2.4 higher than the dose for a conventional V/Q scintigraphy, but in the same range than the radiation exposure when performing common PET procedures, both in terms of total effective dose or finger dose. These results should be reassuring for the healthcare workers performing a V/Q PET procedure.

Quantification of the pulmonary vascular obstruction index on ventilation/perfusion lung scintigraphy: Comparison of a segmental visual scoring to the Meyer score

Introduction

Quantifying the pulmonary vascular obstruction index (PVOI) is essential for the management of patients with pulmonary embolism or chronic thromboembolic pulmonary hypertension (CTEPH). The reference method for quantifying the PVOI with planar lung ventilation/perfusion (V/Q) scintigraphy is the Meyer score, which was validated using pulmonary angiography as a reference standard. However, it is complex to use in daily practice. In contrast, a rapid and fast quantification method consists in estimating the PVOI based on the number of segmental perfusion defects. However, the accuracy of this method has never been evaluated. In this study, we aimed to compare PVOI quantification on planar V/Q scintigraphy assessed by a segmental visual scoring (SVS) to the Meyer score.

Materials and methods

The eligible study population consisted of consecutive patients who underwent planar V/Q scan for CTEPH screening. A central review was performed by three nuclear medicine physicians. PVOI was assessed by summing the number of segmental perfusion defects or equivalent (2 sub-segments = 1 segment = 5%) and by Meyer’s method. The two interpretations were performed 6 months apart. A Spearman rank correlation coefficient was calculated to evaluate correlation between the two measurement methods. An intra-class correlation (ICC) was calculated to assess agreement. A Bland et Altman plot analysis was used to evaluate agreement between the two measurements.

Results

A total of 226 V/Q scans were interpreted. Spearman rank correlation coefficient between SVS and Meyer was 0.963 (95%CI 0.952–0.971) for mismatched perfusion defects and 0.963 (95%CI 0.953–0.972) for perfusion defects regardless of ventilation. Intra-class correlation (ICC) for agreement was 0.978 (95%CI 0.972–0.983) for mismatched perfusion defects and 0.968 (95%CI 0.959–0.976) for perfusion defects regardless of ventilation. In Bland &amp; Altmann analysis, the mean difference between the SVS method and the Meyer score was 0.42 and 0.61 for the mismatched or matched evaluation, respectively.

Conclusion

Our study shows a high correlation, and low differences in PVOI quantification when using a segmental visual scoring (SVS) as compared to the Meyer score. The SVS has the great advantage to be easy and rapid to apply in daily practice.

Lung Ventilation/Perfusion Scintigraphy for the Screening of Chronic Thromboembolic Pulmonary Hypertension (CTEPH): Which Criteria to Use?

Objective

The diagnosis of chronic thromboembolic pulmonary hypertension (CTEPH) is a major challenge as it is a curable cause of pulmonary hypertension (PH). Ventilation/Perfusion (V/Q) lung scintigraphy is the imaging modality of choice for the screening of CTEPH. However, there is no consensus on the criteria to use for interpretation. The aim of this study was to assess the accuracy of various interpretation criteria of planar V/Q scintigraphy for the screening of CTEPH in patients with PH.

Methods

The eligible study population consisted of consecutive patients with newly diagnosed PH in the Brest University Hospital, France. Final diagnosis (CTEPH or non-CTEPH) was established in a referential center on the management of PH, based on the ESC/ERS guidelines and a minimum follow-up of 3 years. A retrospective central review of planar V/Q scintigraphy was performed by three nuclear physicians blinded to clinical findings and to final diagnosis. The number, extent (sub-segmental or segmental) and type (matched or mismatched) of perfusion defects were reported. Sensitivity and specificity were evaluated for various criteria based on the number of mismatched perfusion defects and the number of perfusion defects (regardless of ventilation). Receiver operating characteristic (ROC) curves were generated and areas under the curve (AUC) were calculated for both.

Results

A total of 226 patients with newly diagnosed PH were analyzed. Fifty six (24.8%) were diagnosed with CTEPH while 170 patients (75.2%) were diagnosed with non-CTEPH. The optimal threshold was 2.5 segmental mismatched perfusion defects, providing a sensitivity of 100 % (95% CI 93.6–100%) and a specificity of 94.7% (95%CI 90.3–97.2%). Lower diagnostic cut-offs of mismatched perfusion defects provided similar sensitivity but lower specificity. Ninety five percent of patients with CTEPH had more than 4 segmental mismatched defects. An interpretation only based on perfusion provided similar sensitivity but a specificity of 81.8% (95%CI 75.3–86.9%).

Conclusion

Our study confirmed the high diagnostic performance of planar V/Q scintigraphy for the screening of CTEPH in patients with PH. The optimal diagnostic cut-off for interpretation was 2.5 segmental mismatched perfusion defects. An interpretation only based on perfusion defects provided similar sensitivity but lower specificity.

Risk stratification for predicting recurrent venous thromboembolism after discontinuation of anticoagulation: a post-hoc analysis of a French prospective multicenter study

BACKGROUND

We aimed to validate and to refine current recurrent venous thromboembolism (VTE) risk classification.

METHODS

We performed a post-hoc analysis of a multicentre cohort, including 1,881 patients with a first symptomatic VTE prospectively followed after anticoagulation discontinuation. The primary objective was to validate the International Society of Thrombosis and Haemostasis (ISTH) risk classification in predicting recurrence risk. Secondary objective was to evaluate a refined ISTH classification based on recurrence risk estimate for each individual risk factors.

RESULTS

During a 4.8-year median follow-up after anticoagulation discontinuation, symptomatic recurrent VTE occurred in 230 patients (12.2%). Based on ISTH classification, patients with unprovoked VTE or VTE with minor or major persistent risk factor had a 2-fold increased recurrence risk as compared to those with VTE and major transient risk factor. Recurrence risk was not increased in patients with minor transient factor (Hazard Ratio[HR] 1.31;95%CI0.84-2.06). Individual risk factors analysis identified hormone-related VTE (pregnancy: HR 0.26; 95%CI0.08-0.82; estrogens: HR 0.25; 95%CI0.14-0.47) and amyotrophic lateral sclerosis (HR 5.84; 95%CI1.82-18.70). After reclassification of these factors as major transient for the former and major persistent for the latter, refined ISTH classification allowed to accurately discriminate between patients at low-risk (i.e., with major transient risk factor) and those at high-risk of recurrence (i.e., without major transient risk factors).

CONCLUSIONS

Among patients who stopped anticoagulation after a first VTE, a refined ISTH classification based on recurrence risk intensity of individual factors allowed to discriminate between patients at low-recurrence risk, including hormonal exposure in women, and patients at high-recurrence risk.

Structural and Functional Diversity of Animal Toxins Interacting With GPCRs

Peptide toxins from venoms have undergone a long evolutionary process allowing host defense or prey capture and making them highly selective and potent for their target. This has resulted in the emergence of a large panel of toxins from a wide diversity of species, with varied structures and multiple associated biological functions. In this way, animal toxins constitute an inexhaustible reservoir of druggable molecules due to their interesting pharmacological properties. One of the most interesting classes of therapeutic targets is the G-protein coupled receptors (GPCRs). GPCRs represent the largest family of membrane receptors in mammals with approximately 800 different members. They are involved in almost all biological functions and are the target of almost 30% of drugs currently on the market. Given the interest of GPCRs in the therapeutic field, the study of toxins that can interact with and modulate their activity with the purpose of drug development is of particular importance. The present review focuses on toxins targeting GPCRs, including peptide-interacting receptors or aminergic receptors, with a particular focus on structural aspects and, when relevant, on potential medical applications. The toxins described here exhibit a great diversity in size, from 10 to 80 amino acids long, in disulfide bridges, from none to five, and belong to a large panel of structural scaffolds. Particular toxin structures developed here include inhibitory cystine knot (ICK), three-finger fold, and Kunitz-type toxins. We summarize current knowledge on the structural and functional diversity of toxins interacting with GPCRs, concerning first the agonist-mimicking toxins that act as endogenous agonists targeting the corresponding receptor, and second the toxins that differ structurally from natural agonists and which display agonist, antagonist, or allosteric properties.

Prognostic value of interim FDG PET-CT in patients older than 60 years with diffuse large B-cell lymphoma treated by PMitCEBO plus rituximab. Comparison between Deauville 5-point scale and International Harmonization Project criteria

BACKGROUND

Advanced age is an independent poor prognostic factor of diffuse large B-cell lymphoma (DLBCL). PMitCEBO (mitoxantrone, cyclophosphamide, etoposide, vincristine, bleomycin, and prednisolone) is an alternative to the cyclophosphamide, doxorubicin, vincristine, and prednisolone regimen to decrease side effects in elderly patients. Many studies have shown prognostic value of an interim FDG PET-CT to predict survival. A recent consensus (ICML, Lugano 2013) has suggested using the 5-point scale Deauville criteria instead of those of the International Harmonization Project (IHP) to visually assess the response on interim PET. The objective of this study was to evaluate the prognostic value of an interim FDG PET-CT in patients older than 60 with treated DLBCL and to compare IHP and 5-PS Deauville visual interpretation to predict survival.

METHODS

Forty-eight patients (mean age 73.2±5.2 years) treated by R-PMitCEBO for DLBCL undergoing FDG PET-CT before and after 3 cycles of treatment were retrospectively included. Event-free survival and overall survival were determined by Kaplan-Meier method and compared with interim PET-CT results using IHP and 5-PS Deauville criteria.

RESULTS

Interim PET results using 5-PS Deauville criteria were significantly correlated with EFS (P<0.0001) and OS (P=0.001) whereas they were moderately correlated with EFS (P=0.046) and not with OS (P=0.106) using IHP criteria. Two-year EFS and OS rates were 86.5% and 89.2%, respectively, for patients in 1-3 score group, and 27.3% and 36.4%, respectively, for patients in ≥4 score group using the Deauville criteria.

CONCLUSIONS

Our results confirmed the prognostic value of an interim PET-CT in elderly patients with DLBCL and the better performance of the 5-PS Deauville criteria.

Automatic delineation and quantification of pulmonary vascular obstruction index in patients with pulmonary embolism using Perfusion SPECT-CT: a simulation study

Background

In patients with pulmonary embolism (PE), there is a growing interest in quantifying the pulmonary vascular obtruction index (PVOI), which may be an independent risk factor for PE recurrence. Perfusion SPECT/CT is a very attractive tool to provide an accurate quantification of the PVOI. However, there is currently no reliable method to automatically delineate and quantify it. The aim of this phantom study was to assess and compare 3 segmentation methods for PVOI quantification with perfusion SPECT/CT imaging.

Methods

Three hundred ninety-six SPECT/CT scans, with various PE scenarios (n = 44), anterior to posterior perfusion gradients (n = 3), and lung volumes (n = 3) were simulated using Simind software. Three segmentation methods were assesssed: (1) using an intensity threshold expressed as a percentage of the maximal voxel value (MaxTh), (2) using a Z-score threshold (ZTh) after building a Z-score parametric lung map, and (3) using a relative difference threshold (RelDiffTh) after building a relative difference parametric map. Ninety randomly selected simulations were used to define the optimal threshold, and 306 simulations were used for the complete analysis. Spacial correlation between PE volumes from the phantom data and the delineated PE volumes was assessed by computing DICE_PE indices. Bland-Altman statistics were used to calculate agreement for PVOI between the phantom data and the segmentation methods.

Results

Mean DICE_PE index was higher with the RelDiffTh method (0.85 ± 0.08), as compared with the MaxTh method (0.78 ± 0.16) and the ZTh method (0.67 ± 0.15). Using the RelDiffTh method, mean DICE_PE index remained high (> 0.81) regardless of the perfusion gradient and the lung volumes. Using the RelDiffTh method, mean relative difference in PVOI was − 12%, and the limits of agreement were − 40% to 16%. Values were 3% (− 75% to 81%) for MaxTh method and 0% (− 120% to 120%) for ZTh method. Graphycal analysis of the Bland-Altman graph for the RelDiffTh method showed very close estimation of the PVOI for small and medium PE, and a trend toward an underestimation of large PE.

Conclusion

In this phantom study, a delineation method based on a relative difference parametric map provided a good estimation of the PVOI, regardless of the extent of PE, the intensity of the anterior to posterior gradient, and the whole lung volumes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40658-021-00396-1.

Convolutional neural networks for PET functional volume fully automatic segmentation: development and validation in a multi-center setting

Purpose

In this work, we addressed fully automatic determination of tumor functional uptake from positron emission tomography (PET) images without relying on other image modalities or additional prior constraints, in the context of multicenter images with heterogeneous characteristics.

Methods

In cervical cancer, an additional challenge is the location of the tumor uptake near or even stuck to the bladder. PET datasets of 232 patients from five institutions were exploited. To avoid unreliable manual delineations, the ground truth was generated with a semi-automated approach: a volume containing the tumor and excluding the bladder was first manually determined, then a well-validated, semi-automated approach relying on the Fuzzy locally Adaptive Bayesian (FLAB) algorithm was applied to generate the ground truth. Our model built on the U-Net architecture incorporates residual blocks with concurrent spatial squeeze and excitation modules, as well as learnable non-linear downsampling and upsampling blocks. Experiments relied on cross-validation (four institutions for training and validation, and the fifth for testing).

Results

The model achieved good Dice similarity coefficient (DSC) with little variability across institutions (0.80 ± 0.03), with higher recall (0.90 ± 0.05) than precision (0.75 ± 0.05) and improved results over the standard U-Net (DSC 0.77 ± 0.05, recall 0.87 ± 0.02, precision 0.74 ± 0.08). Both vastly outperformed a fixed threshold at 40% of SUVmax (DSC 0.33 ± 0.15, recall 0.52 ± 0.17, precision 0.30 ± 0.16). In all cases, the model could determine the tumor uptake without including the bladder. Neither shape priors nor anatomical information was required to achieve efficient training.

Conclusion

The proposed method could facilitate the deployment of a fully automated radiomics pipeline in such a challenging multicenter context.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05244-z.

Assessment of Image Quality and Lesion Detectability With Digital PET/CT System

Purpose: The aim of this study was to assess image quality and lesion detectability acquired with a digital Positron Emission Tomography/Computed Tomography (PET/CT) Siemens Biograph Vision 600 system.

Material and Methods: Consecutive patients who underwent a FDG PET/CT during the first week of use of a digital PET/CT (Siemens Biograph Vision 600) at the nuclear medicine department of the university hospital of Brest were analyzed. PET were realized using list mode acquisition. For all patients, 4 datasets were reconstructed. We determined, according to phantom measurements, an equivalent time acquisition/reconstruction parameters pair of the digital PET/CT corresponding to an analog PET/CT image quality (“analog-like”) as reference dataset. We compared the reference dataset with 3 others digital PET/CT reconstruction parameters, allowing a decrease of emission duration: 60, 90, and 120 s per bed position. Three nuclear medicine physicians evaluated independently, for each dataset, overall image quality [Maximal Intensity Projection (MIP), noise, sharpness] using a 4-point scale. Physicians assessed also lesion detection capability by reporting new visible lesions on each digital datasets with their confidence level in comparison with analog-like dataset.

Results: Ninety-eight patients were analyzed. Image quality of MIP (IQ_MIP), sharpness (IQ_SHARPNESS), and noise (IQ_NOISE) of all digital datasets (60, 90, and 120 s) were better than those evaluated with analog-like reconstruction. Moreover, digital PET/CT system improved IQ_MIP, IQ_NOISE, and IQ_SHARPNESS whatever the BMI. Lesion detection capability and confidence level were higher for 60, 90, 120 s per bed position, respectively, than for analog-like images.

Conclusion: Our study demonstrated an improvement of image quality and lesion detectability with a digital PET/CT system.

The Impact of Pulmonary Vascular Obstruction on the Risk of Recurrence of Pulmonary Embolism: A French Prospective Cohort

BACKGROUND

 We aimed to assess whether high pulmonary vascular obstruction index (PVOI) measured at the time of pulmonary embolism (PE) diagnosis is associated with an increased risk of recurrent venous thromboembolism (VTE).

STUDY DESIGN AND METHODS

 French prospective cohort of patients with a symptomatic episode of PE diagnosed with spiral computerized tomography pulmonary angiography (CTPA) or ventilation-perfusion (V/Q) lung scan and a follow-up of at least 6 months after anticoagulation discontinuation. PVOI was assessed based on the available diagnostic exam (V/Q lung scan or CTPA). All patients had standardized follow-up and independent clinicians adjudicated all deaths and recurrent VTE events. Main outcome was recurrent VTE after stopping anticoagulation.

RESULTS

 A total of 418 patients with PE were included. During a median follow-up period of 3.6 (1.2-6.0) years, 109 recurrences occurred. In multivariate analysis, PVOI ≥ 40% was an independent risk factor for recurrence (hazard ratio 1.77, 95% confidence interval 1.20-2.62, p < 0.01), whether PE was provoked by a major transient risk factor or not. A threshold at 41% was identified as the best value associated with the risk of recurrence 6 months after stopping anticoagulation (area under curve = 0.64).

CONCLUSION

 PVOI ≥ 40% at PE diagnosis was an independent risk factor for recurrence VTE. Further prospective validation studies are needed.

Survey by the French Medicine Agency (ANSM) of the imaging protocol, detection rate, and safety of 68Ga-PSMA-11 PET/CT in the biochemical recurrence of prostate cancer in case of negative or equivocal 18F-fluorocholine PET/CT: 1084 examinations

Introduction

Despite growing evidence of a superior diagnostic performance of ⁶⁸Ga-PSMA-11 over ¹⁸F-fluorocholine (FCH) PET/CT, the number of PET/CT centres able to label on site with gallium-68 is still currently limited. Therefore, patients with biochemical recurrence (BCR) of prostate cancer frequently undergo FCH as the 1st-line PET/CT. Actually, the positivity rate (PR) of a second-line PSMA-11 PET/CT in case of negative FCH PET/CT has only been reported in few short series, in a total of 185 patients. Our aims were to check (1) whether the excellent PR reported with PSMA-11 is also obtained in BCR patients whose recent FCH PET/CT was negative or equivocal; (2) in which biochemical and clinical context a high PSMA-11 PET/CT PR may be expected in those patients, in particular revealing an oligometastatic pattern; (3) whether among the various imaging protocols for PSMA-11 PET/CT used in France, one yields a significantly highest PR; (4) the tolerance of PSMA-11.

Patients and methods

Six centres performed ⁶⁸Ga-PSMA-11 PET/CTs during the first 3 years of its use in France. Prior to each PET/CT, the patient’s data were submitted prospectively for authorisation to ANSM, the French Medicine Agency. The on-site readings of 1084 PSMA-11 PET/CTs in BCR patients whose recent FCH PET/CTs resulted negative or equivocal were pooled and analysed.

Results

(1) The overall PR was 68%; for a median serum PSA level (sPSA) of 1.7 ng/mL, an oligometastatic pattern (1–3 foci) was observed in 31% of the cases overall; (2) PR was significantly related to sPSA (from 41% if < 0.2 ng/mL to 81% if ≥ 2 ng/mL), to patients’ age, to initial therapy (64% if prostatectomy vs. 85% without prostatectomy due to frequent foci in the prostate fossa), to whether FCH PET/CT was negative or equivocal (PR = 62% vs. 82%), and to previous BCR (PR = 63% for 1st BCR vs. 72% in case of previous BCR); (3) no significant difference in PR was found according to the imaging protocol: injected activity, administration of a contrast agent and/or of furosemide, dose length product, one single or multiple time points of image acquisition; (4) no adverse event was reported after PSMA-11 injection, even associated with a contrast agent and/or furosemide.

Conclusion

Compared with the performance of PSMA-11 PET/CT in BCR reported independently of FCH PET/CT in 6 large published series (n > 200), the selection based on FCH PET/CT resulted in no difference of PSMA-11 PR for sPSA < 1 ng/mL but in a slightly lower PR for sPSA ≥ 1 ng/mL, probably because FCH performs rather well at this sPSA and very occult BCR was over-represented in our cohort. An oligometastatic pattern paving the way to targeted therapy was observed in one fourth to one third of the cases, according to the clinico-biochemical context of the BCR. Systematic dual or triple acquisition time points or administration of a contrast agent and/or furosemide did not bring a significant added value for PSMA-11 PET/CT positivity and should be decided on individual bases.

Ventilation/perfusion SPECT for the diagnosis of pulmonary embolism: A systematic review

BACKGROUND

Ventilation/perfusion (V/Q) single-photon emission computed tomography (SPECT) has largely replaced conventional planar V/Q scan in nuclear medicine departments for pulmonary embolism (PE) diagnosis. However, the diagnostic performance of the test and its role in the diagnostic management of acute PE are still a matter of debate.

OBJECTIVE

The primary aim was to establish the diagnostic accuracy (sensitivity, specificity) of V/Q SPECT for PE diagnosis. The secondary aim was to review the clinical outcomes of patients investigated for PE suspicion with a standardized algorithm based on V/Q SPECT.

METHODS

We conducted a systematic review of diagnostic accuracy and management outcome studies involving patients evaluated with V/Q SPECT for suspected acute PE. We searched from inception to June 23, 2020, MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials for diagnostic accuracy studies, randomized controlled trials, and observational cohort studies. The methodological quality and risk of bias of eligible studies were assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and the Risk of Bias in Nonrandomized Studies of Interventions tools.

RESULTS

We identified 13 accuracy studies and one prospective outcome study. Eleven diagnostic accuracy studies were deemed at high risk of bias in at least two of the four domains of QUADAS-2 evaluation and a further two studies raised concerns regarding the applicability of results, precluding the meta-analysis for accuracy indices. The only prospective cohort study demonstrated critical risk of bias.

CONCLUSIONS

Although V/Q SPECT has been widely implemented in daily clinical practice, the exact diagnostic performance of V/Q SPECT for PE is still unknown. This systematic review clearly identifies knowledge gaps and sets the agenda for future research.

A snake toxin as a theranostic agent for the type 2 vasopressin receptor

Rationale: MQ1, a snake toxin which targets with high nanomolar affinity and absolute selectivity for the type 2 vasopressin receptor (V2R), is a drug candidate for renal diseases and a molecular probe for imaging cells or organs expressing V2R.

Methods: MQ1's pharmacological properties were characterized and applied to a rat model of hyponatremia. Its PK/PD parameters were determined as well as its therapeutic index. Fluorescently and radioactively labeled MQ1 were chemically synthesized and associated with moderate loss of affinity. MQ1's dynamic biodistribution was monitored by positron emission tomography. Confocal imaging was used to observe the labeling of three cancer cell lines.

Results: The inverse agonist property of MQ1 very efficiently prevented dDAVP-induced hyponatremia in rats with low nanomolar/kg doses and with a very large therapeutic index. PK (plasma MQ1 concentrations) and PD (diuresis) exhibited a parallel biphasic decrease. The dynamic biodistribution showed that MQ1 targets the kidneys and then exhibits a blood and kidney biphasic decrease. Whatever the approach used, we found a T1/2α between 0.9 and 3.8 h and a T1/2β between 25 and 46 h and demonstrated that the kidneys were able to retain MQ1. Finally, the presence of functional V2R expressed at the membrane of cancer cells was, for the first time, demonstrated with a specific fluorescent ligand.

Conclusion: As the most selective V2 binder, MQ1 is a new promising drug for aquaresis-related diseases and a molecular probe to visualize in vitro and in vivo V2R expressed physiologically or under pathological conditions.

Risk scores for occult cancer in patients with unprovoked venous thromboembolism: Results from an individual patient data meta-analysis

BACKGROUND

The Registro Informatizado de Pacientes con Enfermedad TromboEmbólica (RIETE) score and the Screening for Occult Malignancy in Patients with Idiopathic Venous Thromboembolism (SOME) risk scores aim to identify patients with acute unprovoked venous thromboembolism (VTE) at high risk of occult cancer, but their predictive performance is unclear.

METHODS

The scores were evaluated in an individual patient data meta-analysis. Studies were eligible if enrolling consecutive adults with unprovoked VTE who underwent protocol-mandated screening for cancer. The primary outcome was a cancer diagnosis between 30 days and 2 years of follow-up. The discriminatory performance was evaluated by computing the area under the receiver (ROC) curve in random-effects meta-analyses.

RESULTS

The RIETE score could be calculated in 1753 patients, of whom 63 (3.6%) were diagnosed with cancer. The pooled area under the ROC curve was 0.59 (95% confidence interval [CI], 0.52-0.66; I2  = 0%). Of the 427 patients (24%) classified as high risk, 25 (5.9%) were diagnosed with cancer compared with 38 of 1326 (2.9%) low-risk patients (hazard ratio [HR], 2.0; 95% CI, 1.3-3.4). The SOME score was calculated in 925 patients, of whom 37 (4.0%) were diagnosed with cancer. The pooled area under the ROC curve was 0.56 (95% CI, 0.46-0.65; I2  = 46%). Of the 161 patients (17%) classified as high risk (≥2 points), eight (5.0%) were diagnosed with cancer compared with 29 of 764 (3.8%) low-risk patients (HR, 1.2; 95% CI, 0.55-2.7).

CONCLUSIONS

The predictive discriminatory performance of both scores is poor. When used dichotomously, the RIETE score is able to discriminate between low- and high-risk patients. Because this is largely driven by advanced age, these results do not support the use of these scores in daily clinical practice.

Normal Dual Isotope V/Q SPECT Model for Monte-Carlo Studies

Background: There is currently no reliable or validated tool to delineate and quantify functional lung volumes with ventilation/perfusion (V/Q) SPECT/CT. The main challenges encountered include the physiological non-uniformity of lung function, such as the anterior-to-posterior gradient on perfusion images, and the lack of ground truth to assess the accuracy of delineation algorithms. In that respect, Monte-Carlo simulations would be an interesting tool. Thus, the aim of this study was to develop a realistic model of dual-isotope lung V/Q SPECT-CT Monte-Carlo simulations, integrating the anterior to posterior gradient on perfusion.

Methods: Acquisitions and simulations parameters were set in accordance to nuclear medicine guidelines for V/Q lung SPECT-CT. Projections were acquired and simulated, then the reconstructions [with and without attenuation correction (AC)] were compared. A model was built from a patient's CT scan. To model the anterior to posterior gradient, the lungs were divided into sixteen coronal planes, where a rising radioactivity concentration was set. To assess the realism of simulations, they were compared to a normal co-registered normal cases database in terms of pixelwize Z-score map.

Results: For ventilation images, mean (SD) Zscores on Zscore maps were −0.2 (0.7) and −0.2 (0.7) for AC and noAC images, respectively. For perfusion images, mean (SD) Zscores were −0.2 (0.6) and −0.1 (0.6) for AC and noAC images, respectively.

Conclusion: We developed a model for dual isotopes lung V/Q SPECT-CT, integrating the anterior-to-posterior gradient on perfusion images. This model could be used to build a catalog of clinical scenarios, in order to test delineation methods of functional lung volumes.

Evaluation of Venous Thromboembolism Recurrence Scores in an Unprovoked Pulmonary Embolism Population: A Post-hoc Analysis of the PADIS-PE trial

BACKGROUND

We aimed to validate the Men Continue and HERDOO2 (HERDOO2), D-dimer, age, sex, hormonal therapy (DASH), and updated Vienna recurrent venous thromboembolism prediction models in a population composed entirely of first unprovoked pulmonary embolism, and to analyze the impact of the addition of the pulmonary vascular obstruction index (PVOI) on score accuracy.

METHODS

Analyses were based on the double-blind, randomized PADIS-PE trial, which included 371 unprovoked pulmonary embolism patients initially treated for 6 months, successively randomized to receive an additional 18 months of warfarin or placebo, and subsequently followed-up for 2 years.

RESULTS

The HERDOO2, DASH, and updated Vienna scores displayed C-statistics of 0.61 (95% CI 0.54-0.68), 0.60 (95% CI 0.53-0.66), and 0.58 (95% CI 0.51-0.66), respectively. Only the HERDOO2 score identified low recurrence risk patients (<3%/year) after anticoagulation was stopped. When added to either of the prediction models, PVOI measured at pulmonary embolism diagnosis, after 6 months of anticoagulation, or both, improved scores' C-statistics between +0.06 and +0.11 points and consistently led to identifying at least 50% of patients who experienced recurrence but in whom the scores would have indicated against extended anticoagulation.

CONCLUSIONS

In patients with a first unprovoked pulmonary embolism, the HERDOO2 score is able to identify patients with a low recurrence risk after treatment discontinuation. Addition of PVOI improves accuracy of all scores.

CLINICAL TRIALS REGISTRATION

URL: http://www.controlled-trials.com. Unique identifier: NCT00740883.

Integration of 18-FDG PET/CT in the Initial Work-Up to Stage Head and Neck Cancer: Prognostic Significance and Impact on Therapeutic Decision Making

Background: The objective of this study was to assess the therapeutic and prognostic impact of integrating18F-fluorodeoxyglucose (18-FDG) positron emission tomography (PET)/computed tomography (CT) into work-up (WU) at initial staging of patients with head and neck squamous cell carcinoma (HNSCC).

Method: 477 consecutive patients (414M/63F, mean age 62.3 ± 9.7 years) with newly diagnosed HNSCC who underwent pre-treatment 18-FDG PET/CT were retrospectively included. The 18-FDG PET/CT stage (sPET) was compared to the conventional work-up stage (sCWU). A group of cancer specialists determined whether integrating PET/CT into WU at initial staging had an impact on the therapeutic decision, classifying the clinical impact as high (change in therapeutic modality), medium (change in the radiotherapy or surgical procedure), or low (modification of TNM staging and/or detection of synchronous cancer without high or medium impact). Three-year overall survival (OS) was considered as primary endpoint of the prognostic analysis.

Results: 18-FDG PET/CT had a clinical impact in 221 patients (46.3%) with a medium or high impact on management in 94 (19.5%) patients. Medium and high impact of 18-FDG PET/CT was statistically equivalent between sCWU-stage I/II and III/IV subgroups (p = 0.02). 42 patients were PET/CT-upstaged from early stage I/II to advanced stage III/IV and had a significantly lower 3-year OS than those with concordant CWU and 18-FDG PET/CT early stage (54.8 vs. 82.6%, p = 0.001).

Conclusion: This study demonstrated that implementing 18-FDG PET/CT in the initial WU of HNSCC provides valuable staging information with a better prognostic stratification. Patient management was modified for any disease stage, even for early stage I-II, with consequences on survival.

Performance comparison of modified ComBat for harmonization of radiomic features for multicenter studies

Multicenter studies are needed to demonstrate the clinical potential value of radiomics as a prognostic tool. However, variability in scanner models, acquisition protocols and reconstruction settings are unavoidable and radiomic features are notoriously sensitive to these factors, which hinders pooling them in a statistical analysis. A statistical harmonization method called ComBat was developed to deal with the "batch effect" in gene expression microarray data and was used in radiomics studies to deal with the "center-effect". Our goal was to evaluate modifications in ComBat allowing for more flexibility in choosing a reference and improving robustness of the estimation. Two modified ComBat versions were evaluated: M-ComBat allows to transform all features distributions to a chosen reference, instead of the overall mean, providing more flexibility. B-ComBat adds bootstrap and Monte Carlo for improved robustness in the estimation. BM-ComBat combines both modifications. The four versions were compared regarding their ability to harmonize features in a multicenter context in two different clinical datasets. The first contains 119 locally advanced cervical cancer patients from 3 centers, with magnetic resonance imaging and positron emission tomography imaging. In that case ComBat was applied with 3 labels corresponding to each center. The second one contains 98 locally advanced laryngeal cancer patients from 5 centers with contrast-enhanced computed tomography. In that specific case, because imaging settings were highly heterogeneous even within each of the five centers, unsupervised clustering was used to determine two labels for applying ComBat. The impact of each harmonization was evaluated through three different machine learning pipelines for the modelling step in predicting the clinical outcomes, across two performance metrics (balanced accuracy and Matthews correlation coefficient). Before harmonization, almost all radiomic features had significantly different distributions between labels. These differences were successfully removed with all ComBat versions. The predictive ability of the radiomic models was always improved with harmonization and the improved ComBat provided the best results. This was observed consistently in both datasets, through all machine learning pipelines and performance metrics. The proposed modifications allow for more flexibility and robustness in the estimation. They also slightly but consistently improve the predictive power of resulting radiomic models.

Correlation Between FDG Hotspots on Pre-radiotherapy PET/CT and Areas of HNSCC Local Relapse: Impact of Treatment Position and Images Registration Method

Aim: Several series have already demonstrated that intratumoral subvolumes with high tracer avidity (hotspots) in 18F-flurodesoxyglucose positron-emission tomography (FDG-PET/CT) are preferential sites of local recurrence (LR) in various solid cancers after radiotherapy (RT), becoming potential targets for dose escalation. However, studies conducted on head and neck squamous cell carcinoma (HNSCC) found only a moderate overlap between pre- and post-treatment subvolumes. A limitation of these studies was that scans were not performed in RT treatment position (TP) and were coregistred using a rigid registration (RR) method. We sought to study (i) the influence of FDG-PET/CT acquisition in TP and (ii) the impact of using an elastic registration (ER) method to improve the localization of hotpots in HNSCC.

Methods: Consecutive patients with HNSCC treated by RT between March 2015 and September 2017 who underwent FDG-PET/CT in TP at initial staging (PET_A) and during follow-up (PET_R) were prospectively included. We utilized a control group scanned in non treatment position (NTP) from our previous retrospective study. Scans were registered with both RR and ER methods. Various sub-volumes (A_X; x = 30, 40, 50, 60, 70, 80, and 90%SUVmax) within the initial tumor and in the subsequent LR (R_X; x = 40 and 70%SUVmax) were overlaid on the initial PET/CT for comparison [Dice, Jaccard, overlap fraction = OF, common volume/baseline volume = A_XnR_X/A_X, common volume/recurrent volume = A_XnR_X/R_X].

Results: Of 199 patients included, 43 (21.6%) had LR (TP = 15; NTP = 28). The overlap between A₃₀, A₄₀, and A₅₀ sub-volumes on PET_A and the whole metabolic volume of recurrence R₄₀ and R₇₀ on PET_R showed moderate to good agreements (0.41–0.64) with OF and A_XnR_X/R_X index, regardless of registration method or patient position. Comparison of registration method demonstrated OF and A_XnR_X/R_X indices (x = 30% to 50%SUVmax) were significantly higher with ER vs. RR in NTP (p < 0.03), but not in TP. For patient position, the OF and A_XnR_X/R_X indices were higher in TP than in NTP when RR was used with a trend toward significance, particularly for x=40%SUVmax (0.50±0.22 vs. 0.31 ± 0.13, p = 0.094).

Conclusion: Our study suggested that PET/CT acquired in TP improves results in the localization of FDG hotspots in HNSCC. If TP is not possible, using an ER method is significantly more accurate than RR for overlap estimation.

V/Q SPECT for the Assessment of Regional Lung Function: Generation of Normal Mean and Standard Deviation 3-D Maps

Background: V/Q SPECT/CT is attractive for regional lung function assessment, but accurate delineation and quantification of functional lung volumes remains a challenge. Physiological intra and inter patient non-uniformity of V/Q SPECT images make conventional delineation methods of functional lung volumes inaccurate. In that context it would be of interest to build statistical maps of normal V/Q SPECT to assess the physiological variability of radiotracers. The aim of this study was to generate normal mean and standard deviation maps of regional lung function as assessed with V/Q SPECT/CT, with (AC) and without (NoAC) attenuation correction. Methods: During a 13 month period, 73 consecutive patients referred for suspected acute pulmonary embolism, that had normal V/Q SPECT/CT based on the interpretation of 2 independent nuclear medicine physicians, were selected. Four set of images were reconstructed: perfusion and ventilation images, AC, and NoAC, respectively. Statistical maps were created as follows: all cases were registered to a reference scan using the CT data, first with a rigid then with a non-rigid method. SPECTs reconstructions were then co-registered and normalized, and mean and standard deviation voxel-wise maps were calculated. To assess the consistency of generated maps to lung physiology and the potential impact of non-rigid registration, visual analysis and quantitative comparison with non-registered data were performed in the whole series. Quantitative comparison was also conducted in two randomly sampled independent subsets. Results: Perfusion mean maps showed a continuous negative posterior to anterior gradient, majored on the AC mean map. Perfusion standard deviation maps showed higher variability in the periphery of the lungs, but especially in the posterior areas. The ventilation mean map showed a slightly positive posterior to anterior gradient on NoAC mean ventilation map, while the AC mean map showed no gradient. The NoAC ventilation SD map showed a higher variability in the periphery of the lungs as compared with AC SD map. No statistical difference in the posterior to anterior gradient measurements was found between the generated mean statistical maps and the non-registered data, either in the whole series or across the two independent datasets. Conclusion: We proposed a methodology to create statistical normal maps for V/Q SPECTs. Maps were consistent with the known physiological non-uniformity and showed the impact of attenuation correction on the posterior to anterior gradient. These maps could be used for a Z-score analysis, and a better segmentation of healthy uptake areas.

[Alamandine, a molecule of therapeutic interest against cardiac hypertrophy]

Pour la cinquième année, dans le cadre du module d’enseignement « Physiopathologie de la signalisation » proposé par l’université Paris-sud, les étudiants du Master « Biologie Santé » de l’université Paris-Saclay se sont confrontés à l’écriture scientifique. Ils ont sélectionné une quinzaine d’articles scientifiques récents dans le domaine de la signalisation cellulaire présentant des résultats originaux, via des approches expérimentales variées, sur des thèmes allant des relations hôte-pathogène aux innovations thérapeutiques, en passant par la signalisation hépatique et le métabolisme. Après un travail préparatoire réalisé avec l’équipe pédagogique, les étudiants, organisés en binômes, ont ensuite rédigé, guidés par des chercheurs, une Nouvelle soulignant les résultats majeurs et l’originalité de l’article étudié. Ils ont beaucoup apprécié cette initiation à l’écriture d’articles scientifiques et, comme vous pourrez le lire, se sont investis dans ce travail avec enthousiasme ! Trois de ces Nouvelles sont publiées dans ce numéro, les autres le seront dans des prochains numéros.

Feasibility Study and Preliminary Results of Prognostic Value of Bone SPECT-CT Quantitative Indices for the Response Assessment of Bone Metastatic Prostate Carcinoma to Abiraterone

Objective: We assessed the prognostic value of quantitative indices extracted from bone SPECT-CT to evaluate the response of bone metastatic castrate-resistant prostate cancer (BmCRPC) to abiraterone.

Methods: Consecutive patients with BmCRPC initiating treatment with abiraterone from March 2014 to March 2015 were prospectively included. Three 2-bed SPECT-CT [at baseline [M0], after 3 months [M3], and 6 months [M6] of treatment], were planned (Symbia Intevo^®, Siemens). SPECT data were reconstructed using an Ordered Subset Conjugate Gradient Minimization (OSCGM) algorithm allowing SUV quantification. SUVmax and SUVpeak of the highest uptake lesion were measured in each SPECT-CT. Total Neoplastic Osteoblastic Metabolic Volume (NOMV) was assessed. PSA level was recorded at baseline, M3, and M6 of treatment. Overall survival (OS), progression-free survival (PFS), and disease-specific survival (DSS) were calculated.

Results: Nineteen patients aged 71.1 ± 7.7 years were included. Low M0 SUVmax was significantly predictive of longer OS (p = 0.04). Low NOMV at M0 were significantly predictive of longer PFS (p = 0.02). Patients with increase of at least 12.5% of the SUVpeak of the highest uptake lesion between M0 and M3 (ΔSUVpeakM0M3) had a significantly longer OS (p = 0.03). Patients with increase (or decrease lesser than 25%) of ΔSUVpeakM0M3 had a significantly longer DSS (p = 0.01). Patients with increase of NOMV of at least 45% between M0 and M6 had a significantly shorter PFS (p < 0.001). Variations of NOMV between M0 and M6 were significantly correlated with PSA variations between M0 and M6 (rs = 0.73, p = 0.02).

Conclusions: Quantitative bone SPECT-CT appears to be a promising tool of BmCRPC assessment. Early flare-up phenomenon seems to predict longer OS.

Evaluation of the predictive value of the bleeding prediction score VTE-BLEED for recurrent venous thromboembolism

INTRODUCTION

VTE-BLEED is a validated score for identification of patients at increased risk of major bleeding during extended anticoagulation for venous thromboembolism (VTE). It is unknown whether VTE-BLEED high-risk patients also have an increased risk for recurrent VTE, which would limit the potential usefulness of the score.

METHODS

This was a post hoc analysis of the randomized, double-blind, placebo-controlled PADIS-PE trial that randomized patients with a first unprovoked pulmonary embolism (PE) initially treated during 6 months to receive an additional 18-month of warfarin vs. placebo. The primary outcome of this analysis was recurrent VTE during 2-year follow-up after anticoagulant discontinuation, that is, after the initial 6-month treatment in the placebo arm and after 24 months of anticoagulation in the active treatment arm. This rate, adjusted for study treatment allocation, was compared between patients in the high- vs. low-risk VTE-BLEED group.

RESULTS

In complete case analysis (n = 308; 82.4% of total population), 89 (28.9%) patients were classified as high risk; 44 VTE events occurred after anticoagulant discontinuation during 668 patient-years. The cumulative incidence of recurrent VTE was 16.4% (95% confidence interval [CI], 10.0%-26.1%; 14 events) and 14.6% (95% CI, 10.4%-20.3%; 30 events) in the high-risk and low-risk VTE-BLEED groups, respectively, for an adjusted hazard ratio of 1.16 (95% CI, 0.62-2.19).

CONCLUSION

In this study, patients with unprovoked PE classified at high risk of major bleeding by VTE-BLEED did not have a higher incidence of recurrent VTE after cessation of anticoagulant therapy, supporting the potential yield of the score for making management decisions on the optimal duration of anticoagulant therapy.

Predictors for Residual Pulmonary Vascular Obstruction after Unprovoked Pulmonary Embolism: Implications for Clinical Practice—The PADIS-PE Trial

Background We aimed to identify risk factors for residual pulmonary vascular obstruction after a first unprovoked pulmonary embolism (PE).

Methods Analyses were based on data from the double-blind randomized “PADIS-PE” trial that included 371 patients with a first unprovoked PE initially treated during 6 uninterrupted months; all patients underwent baseline ventilation–perfusion lung scanning at inclusion (i.e., after 6 months of anticoagulation). Each patient's pulmonary vascular obstruction indexes (PVOIs) at PE diagnosis and at inclusion were centrally assessed.

Results Among the 371 included patients, residual PVOI was available in 356 patients, and 150 (42.1%) patients had PVOI ≥ 5%. At multivariable analysis, age > 65 years (odds ratio [OR], 2.81, 95% confidence interval [CI], 1.58–5.00), PVOI ≥ 25% at PE diagnosis (OR, 3.53, 95% CI, 1.94–6.41), elevated factor VIII (OR, 3.89, 95% CI, 1.41–10.8), and chronic respiratory disease (OR, 2.18, 95% CI, 1.11–4.26) were independent predictors for residual PVOI ≥ 5%. Patients with ≥ 1 of these factors represented 94.5% (123 patients) of all patients with residual PVOI ≥ 5%.

Conclusion Six months after a first unprovoked PE, age > 65 years, PVOI ≥ 25% at PE diagnosis, elevated factor VIII, or chronic respiratory disease were found to be independent predictors for residual pulmonary vascular obstruction.

Clinical Trials Registration URL: http://www.controlled-trials.com. Unique identifier: NCT00740883.

Diagnostic value of positron-emission tomography textural indices for malignancy of 18F-fluorodeoxyglucose-avid adrenal lesions

BACKGROUND

PET Textural indices could have an add-on diagnostic value for diagnosis of malignancy in patients with FDG-avid adrenal lesions.

METHODS

Consecutive patients referred for a FDG-PET/CT to our nuclear medicine department from June 2012 to June 2017 were retrospectively screened. Inclusion criteria were: patients with a FDG-avid adrenal lesion (uptake≥liver background); malignant/benign lesion confirmed histologically or with follow-up imaging examination. Pheochromocytomas were not included in the analysis. For each adrenal lesion, 5 quantitative PET parameters (SUV<inf>max</inf>, MTV, TLG, TLR<inf>max</inf> and TLRmean<inf>)</inf> were calculated. Thirty-seven textural indices were extracted using LIFEx software^®. Diagnostic performance to determine malignancy was assessed with a ROC analysis. Parameters with a significantly AUC>0.5 were selected and groups of highly correlated (r>0.8) parameters were created. A scoring system combining PET and textural indices was examined.

RESULTS

PET textural indices were calculated for 53 lesions (37 malignant, 16 benign). Three PET metabolic parameters (SUV<inf>max</inf>, TLR<inf>max</inf>, TLRmean) and 13 textural indices had an AUC>0.5. Seven groups of highly correlated parameters (r>0.8) were extracted. For PET parameters, SUV<inf>max</inf> had the best AUC (0.89 95% CI [0.79-0.98]; cut-off=7.0). For textural indices, ZLNU had the best AUC (0.87 95% CI [0.78-0.96]; cut-off=34.7) and specificity of 100%. Three scores combining the best four textural indices alone (Contrast<inf>GLCM</inf>, LRHGE, SZE and ZLNU) or with one PET parameters (SUV<inf>max</inf>, TLR<inf>max</inf>) were developed but did not increase the diagnostic performance (AUC≤0.89). ZLNU was the best parameter to distinguish primary adrenal cancer from adrenal metastases in malignant lesions (P<0.001).

CONCLUSIONS

Our study highlighted excellent diagnostic performance of several PET textural indices comparable to that of PET metabolic parameters. However, our results did not find any additional diagnostic value of textural indices when combined with metabolic parameters.

Diagnostic Value of FDG PET-CT Quantitative Parameters and Deauville-Like 5 Point-Scale in Predicting Malignancy of Focal Thyroid Incidentaloma

Objective: To evaluate the diagnostic value of FDG PET-CT metabolic parameters and Deauville-like 5 point-scale to predict malignancy in a population of patients presenting focal thyroid incidentaloma (fTI).

Design: This retrospective study included 41 fTI, classified according to cytological and histological data as benign (BL) or malignant lesion (ML). FDG PET-CT semi-quantitative parameters (SUVmax, SUVmean, SUVpeak, MTV, TLG), tumor to liver SUVmean ratio (TLRmax and TLRmean), tumor to blood-pool SUVmean ratio (TBRmax and TBRmean) were calculated. Each fTI was also classified on a Deauville-like 5-point scale (DS) currently used in lymphoma. Comparison between BL and ML was performed for each parameter and a ROC analysis was conducted.

Results: All quantitative PET metabolic parameters (SUV parameters, volume based parameters and SUV ratio) were higher in ML compared with BL, yet no significant difference was reported. fTI (uptake) malignancy rate according to DS grades 2, 3, 4, and 5 was, respectively, 25% (1 of 4), 28.6% (2 of 7), 8.3% (1 of 12), and 33.3% (6 of 18) with no significant difference between ML and BL groups. Results of ROC analysis showed that mean TBR had the highest AUC in our cohort (0.66 95%CI [0.41; 0.91]) with a cut-off value of 2.2. Specificity of MTV and TLG was 100% (cut-off values: MTV 9.6 ml, TLG 22.9 g) and their sensitivity was 30 and 40%, respectively.

Conclusion: Our study did not highlight any FDG PET/CT parameter predictor of fTI malignancy.

Prognostic value of textural indices extracted from pretherapeutic 18-F FDG-PET/CT in head and neck squamous cell carcinoma

BACKGROUND

This study aimed at assessing the prognostic value of textural indices extracted from 18F-fluorodeoxyglucose positron-emission tomography (FDG-PET)/CT in a large cohort of patients with head and neck squamous cell carcinomas (HNSCC) of any anatomic subsite and staging.

METHODS

Consecutive patients with HNSCC referred for a pretreatment FDG-PET/CT were retrospectively included and followed up for a minimum of 2 years. Standardized uptake value, metabolic tumor volume (MTV), and textural indices were calculated using LIFEx software. Prognostic significance of parameters was assessed in univariate and multivariate analysis.

RESULTS

Textural indices were extracted in 284 patients (mean age = 63.7±9.6 years). In univariate analysis, MTV and 4 textural indices-Correlation, Entropy, Energy, and Coarseness-were significantly correlated with overall survival (OS). In multivariate analysis, MTV (P = .008) and Correlation (P = .028) remained independently correlated to OS.

CONCLUSION

This study showed that MTV and 1 textural index extracted from pretherapeutic FDG-PET/CT (Correlation) were independent prognostic factors of OS in patients with HNSCC.

Residual pulmonary vascular obstruction and recurrence after acute pulmonary embolism: protocol for a systematic review and meta-analysis of individual participant data

BACKGROUND

In patients with a first, unprovoked venous thromboembolism (VTE), the optimal duration of anticoagulant therapy (AT) is controversial due to tightly balanced risks and benefits of indefinite anticoagulation. The objective of this study is to assess among patients with a first acute pulmonary embolism (PE) who received ≥3 months of AT and thereafter had a planar lung scan, whether residual pulmonary vascular obstruction (RPVO) is associated with VTE recurrence after discontinuation of AT.

METHODS AND ANALYSIS

We will conduct a systematic review with a meta-analysis of individual participant data of contemporary studies evaluating the prognostic significance of RPVO in patients with a first acute PE. We will search from inception to 24 January 2018, PubMed, Medline, Embase and Cochrane's Central Registry for Randomized Controlled Trials, CENTRAL for randomized controlled trials and prospective cohort studies. Two reviewers will conduct all screening and data collection independently. The methodological quality and risk of bias of eligible studies will be carefully and rigorously assessed using the Risk Of Bias In Non-randomised Studies of Interventions tool. The primary objective will be to assess the relationship between RPVO on ventilation-perfusion scan after completion of at least 3 months of AT after an acute PE event, and the risk of an objectively confirmed symptomatic recurrent VTE (including deep vein thrombosis or PE) or death due to PE. The secondary objectives will include the assessment of the optimal RPVO cut-off and the risk of recurrent VTE, as well as the relationship between the relative change in RPVO between PE diagnosis and at discontinuation of AT (≥3 months) and risk of recurrent VTE.

ETHICS AND DISSEMINATION

This study of secondary data does not require ethics approval. It will be presented internationally and published in the peer-reviewed literature.

PROSPERO REGISTRATION NUMBER

CRD42017081080.

Revisiting occult cancer screening in patients with unprovoked venous thromboembolism

Unprovoked venous thromboembolism (VTE) can be the first manifestation of an unknown cancer. A recently published individual patient data meta-analysis (IPDMA) reported a prevalence of occult cancer detection of 5.2% (95% CI, 4.1% to 6.5%) over a one-year follow-up period, approximately 50% lower than the previously reported 12-month period prevalence. Although an extensive screening strategy was associated with a 2-fold higher probability of cancer detection at initial screening in the IPDMA, not enough evidence exists yet to support the routine use of these tests in patients with unprovoked VTE. It is likely that a subgroup of patients with unprovoked VTE is at higher risk of occult cancer detection and might benefit from closer clinical surveillance. A newly derived and validated clinical predictive rule seems to be able to stratify patients with unprovoked VTE accordingly to their underlying risk of occult cancer detection. The low incidence of occult cancer detection (<3%) in the low-risk group is reassuring for clinicians. Future studies are required to better define the risks and benefits of an extensive occult cancer screening strategy in high risk patients sub-group with unprovoked VTE. To date, the Scientific and Standardized Committee from the International Society of Thrombosis and Haemostasis suggests that patients with unprovoked VTE should only undergo a limited cancer screening including thorough medical history and physical examination, basic laboratory investigations, chest X-ray as well as age- and gender-specific cancer screening according to national guidelines.

In patients with unprovoked VTE, does the addition of FDG PET/CT to a limited occult cancer screening strategy offer good value for money? A cost-effectiveness analysis from the publicly funded health care systems

INTRODUCTION

Unprovoked venous thromboembolism (VTE) may be the first manifestation of an undiagnosed cancer. We assessed the cost-effectiveness of ¹⁸F-Fluorodesoxyglucose Positron Emission/Computed Tomography (FDG PET/CT) plus limited screening and limited screening strategies in patients with unprovoked VTE from the perspectives of the Ontario (Canada) and French health care systems.

METHODS

We conducted a cost-effectiveness analysis based on a published randomized controlled trial of 394 patients aged 18 years or older who were diagnosed with unprovoked VTE. We obtained data with respect to efficacy and health care utilization from the published trial. The primary measure of effectiveness was the number of avoided cases of delayed cancer diagnosis and the secondary measure of effectiveness was the quality adjusted life year (QALY) at the end of the study in each group. We used generalized linear models to estimate incremental cost-effectiveness ratios (ICER) while controlling for patient demographic and clinical characteristics. Results were presented as the incremental cost to avoid one case of delayed cancer diagnosis and the incremental cost per QALY gained. The 95% confidence intervals (CIs) were estimated using bootstrap re-sampling procedures with 5000 iterations.

RESULTS

Compared to a limited screening strategy, the ICER of limited strategy plus FDG PET/CT scan was C$ 26,840.19 (95% CI: C$ 24,046.51; C$ 34,581.53) per one avoided case of delayed cancer diagnosis from the Ontario health system perspective and €16,370.45 (95% CI: € 9904.48; € 39,578.91) per one avoided case of delayed cancer diagnosis from the French health system perspective. The probabilities that addition of FDG PET/CT to limited screening is cost-effective rose with increasing willingness to pay values. Compared with the limited screening, the extensive screening was associated with C$ 3412.85 per QALY gained (95% CI: 1463.89; -13,935.88) from the Ontario health system perspective and €2162.83 per QALY gained (95% CI 958.78; -10,544.42) from the French health system perspective.

CONCLUSION

Addition of a FDG PET/CT for occult cancer diagnosis was associated with better health outcomes (fewer cases of delayed cancer diagnosis and greater QALYs) and a higher cost from the perspective of publicly funded health care systems; the cost-effectiveness results are however highly uncertain.

An aortic intra mural hematoma in ventilation/perfusion SPECT/CT: A case report

RATIONALE

Ventilation/perfusion (V/Q) single-photon-emission computed tomography (SPECT) has arisen as an alternative to computed tomography pulmonary angiography (CTPA) in patients with pulmonary embolism (PE) suspicion. The addition of low dose CT (ldCT) to V/Q SPECT improves the specificity of the test, allowing for potential alternative diagnosis.

PATIENT CONCERNS AND DIAGNOSIS

Here we presented a case of an aortic intramural hematoma (IMH) diagnosed on the ldCT portion of V/Q SPECT combined with CT. A 74-year-old man suffering from sudden-onset chest pain was referred to our nuclear medicine department for PE suspicion.

INTERVENTION AND OUTCOME

A V/Q SPECT combined with nonenhanced ldCT ruled out PE diagnosis. Nevertheless, ldCT revealed high attenuation aortic wall thickening suggestive of aortic IMH. Chest CT angiography showed mild dilatation and circumferential thickening of aortic wall confirming Stanford type A IMH involving the entire ascending aorta.

LESSON

This case illustrates the potential usefulness of combining ldCT to V/Q SPECT in providing alternative diagnosis in suspected PE patients.

Autonomously binding protein detected on ets box of c-fos serum response element in proliferating cells

The serum response element (SRE) in the c-fos promoter contains an ets box whose integrity is required for full activation of this proto-oncogene by nerve growth factor (NGF) in PC12 rat pheochromocytoma cells. Electrophoretic mobility shift assays (EMSA) detect a protein in nuclear extracts that binds to the wild-type SRE, but not to an SRE containing a mutated ets box. Competition studies using unlabeled probes, and supershift experiments using antibodies and in vitro translated core serum response factor (SRF) indicate that the protein in question is not YY1, SAP-1, nor Elk-1 and that it does not exhibit ternary complex factor (TCF) activity, so that it may correspond to an autonomously binding Ets family protein. The complete disappearance of this "Ets-like autonomous binding factor" upon terminal differentiation of both L6alpha2 myoblastic and PC12 pheochromocytoma cells points to a possible role in the proliferation/differentiation process.

Clinical interest of quantitative bone SPECT-CT in the preoperative assessment of knee osteoarthritis

The aim of the study was to evaluate the interest of quantitative bone SPECT-CT in the preoperative assessment of knee osteoarthritis (OA) before unicompartmental knee arthroplasty (UKA).Patients eligible for UKA were prospectively included in 2 centers and underwent a preoperative SPECT-CT. Images were reconstructed with an OSEM, an OSCGM (allowing SUV quantification) and an enhanced OSCGM (containing uptakes to bones) algorithms. Visual analysis and quantification (SUVmax) were performed for each compartment (medial compartment [MC], lateral compartment [LC], and patellofemoral compartment [PFC]). Clinical data were preoperatively assessed. The gold standard was the per-operative OA staging (International Cartilage Repair Society [ICRS] scale). Spearman's correlation coefficient was used for correlations. Sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), and accuracy of SPECT-CT were assessed.One hundred three patients (50 women, 53 men, mean age = 64.5 ± 10.3 y/o, 120 preoperative knees) were analyzed. There was no correlation between SUVmax and clinical data. There was a correlation between ICRS staging and SUVmax with both OSCGM (MC [rs = 0.25], LC [rs = 0.51], and PFC [rs = 0.27]), and enhanced OSCGM, except in the PFC (MC [rs = 0.22], LC [rs = 0.62], and PFC [rs = 0.03]). The Se, Sp, PPV, NPV, and accuracy of SPECT-CT were, respectively, 0.99, 0.67, 0.98, 0.80, 0.97 for the MC; 0.50, 0.85, 0.42, 0.89, 0.79 for the LC; and 0.23, 0.86, 0.50, 0.64, 0.62 for the PFC.Bone SPECT-CT SUVmax is correlated with per-operative OA staging. Despite the low sensitivity of SPECT-CT in the LC, its high specificity in the LC should prompt the surgeon to be vigilant before UKA surgery.

SPECT V/Q for the diagnosis of pulmonary embolism: protocol for a systematic review and meta-analysis of diagnostic accuracy and clinical outcome

INTRODUCTION

Single photon emission computed tomography ventilation/perfusion (SPECT V/Q) imaging has many proponents within the nuclear medicine community and has already largely replaced planar V/Q scintigraphy in daily practice for the diagnosis of pulmonary embolism (PE). However, the test is still described in clinical guidelines as an experimental test because of insufficient evidence.

METHODS AND ANALYSIS

We will conduct a systematic review and a meta-analysis of diagnostic accuracy and management outcome studies involving patients evaluated with V/Q SPECT for suspected acute PE. We will search from inception to 19 December 2017 MEDLINE, Embase and the Cochrane Central Register of Controlled Trials for diagnostic accuracy studies, randomised controlled trials and observational cohort studies. Two reviewers will conduct all screening and data collection independently. The methodological quality and risk of bias of eligible studies will be carefully and rigorously assessed using the Quality Assessment of Diagnostic Accuracy Studies-2, the Cochrane Collaboration's tool and the Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tools. The primary outcomes will be sensitivity, specificity and likelihood ratios of V/Q SPECT for the diagnosis of acute PE. The secondary outcomes will be the rate of venous thromboembolism during a 3-month follow-up period in patients left untreated after a negative diagnostic work-up based on SPECT V/Q.

ETHICS AND DISSEMINATION

This study of secondary data does not require ethics approval. It will be presented internationally and published in the peer-reviewed literature.

PROSPERO REGISTRATION NUMBER

CRD42018084095.

Feasibility of Systematic Respiratory-Gated Acquisition in Unselected Patients Referred for 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Objective

Respiratory motion in ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) induces blurred images, leading to errors in location and quantification for lung and abdominal lesions. Various methods have been developed to correct for these artifacts, and most of current PET/CT scanners are equipped with a respiratory gating system. However, they are not routinely performed because their use is time-consuming. The aim of this study is to assess the feasibility and quantitative impact of a systematic respiratory-gated acquisition in unselected patients referred for FDG PET/CT, without increasing acquisition time.

Methods

Patients referred for a FDG PET/CT examination to the nuclear medicine department of Brest University Hospital were consecutively enrolled, during a 3-month period. Cases presenting lung or liver uptakes were analyzed. Two sets of images were reconstructed from data recorded during a unique acquisition with a continuous table speed of 1 mm/s of the used Biograph mCT Flow PET/CT scanner: standard free-breathing images, and respiratory-gated images. Lesion location and quantitative parameters were recorded and compared.

Results

From October 1 2015 to December 31 2015, 847 patients were referred for FDG PET/CT, 741 underwent a respiratory-gated acquisition. Out of them, 213 (29%) had one or more lung or liver uptake but 82 (38%) had no usable respiratory-gated signal. Accordingly, 131 (62%) patients with 183 lung or liver uptakes were analyzed. Considering the 183 lesions, 140 and 43 were located in the lungs and the liver, respectively. The median (IQR) difference between respiratory-gated images and non-gated images was 18% (4−32) for SUVmax, increasing to 30% (14−57) in lower lobes for lung lesions, and −18% (−40 to −4) for MTV (p < 0.05). Technologists’ active personal dosimetry and mean total examinations duration were not statistically different between periods with and without respiratory gating.

Conclusion

This study showed that a systematic respiratory-gated acquisition without increasing acquisition time is feasible in a daily routine and results in a significant impact on PET quantification. However, clinical impact on patient management remains to be determined.