Multicentric development and evaluation of 18F-FDG PET/CT and MRI radiomics models to predict para-aortic lymph node involvement in locally advanced cervical cancer.

PURPOSE: To develop machine learning models to predict para-aortic lymph node (PALN) involvement in patients with locally advanced cervical cancer (LACC) before chemoradiotherapy (CRT) using 18F-FDG PET/CT and MRI radiomics combined with clinical parameters. METHODS: We retrospectively collected 178 patients (60% for training and 40% for testing) in 2 centers and 61 patients corresponding to 2 further external testing cohorts with LACC between 2010 to 2022 and who had undergone pretreatment analog or digital 18F-FDG PET/CT, pelvic MRI and surgical PALN staging. Only primary tumor volumes were delineated. Radiomics features were extracted using the Radiomics toolbox®. The ComBat harmonization method was applied to reduce the batch effect between centers. Different prediction models were trained using a neural network approach with either clinical, radiomics or combined models. They were then evaluated on the testing and external validation sets and compared. RESULTS: In the training set (n = 102), the clinical model achieved a good prediction of the risk of PALN involvement with a C-statistic of 0.80 (95% CI 0.71, 0.87). However, it performed in the testing (n = 76) and external testing sets (n = 30 and n = 31) with C-statistics of only 0.57 to 0.67 (95% CI 0.36, 0.83). The ComBat-radiomic (GLDZM_HISDE_PET_FBN64 and Shape_maxDiameter2D3_PET_FBW0.25) and ComBat-combined (FIGO 2018 and same radiomics features) models achieved very high predictive ability in the training set and both models kept the same performance in the testing sets, with C-statistics from 0.88 to 0.96 (95% CI 0.76, 1.00) and 0.85 to 0.92 (95% CI 0.75, 0.99), respectively. CONCLUSIONS: Radiomic features extracted from pre-CRT analog and digital 18F-FDG PET/CT outperform clinical parameters in the decision to perform a para-aortic node staging or an extended field irradiation to PALN. Prospective validation of our models should now be carried out.

Scan-rescan measurement repeatability of 18F-FDG PET/MR imaging of vascular inflammation.

Non-invasive positron emission tomography (PET) of vascular inflammation and atherosclerotic plaque by identifying increased uptake of 18F-fluordeoxyglucose (18F-FDG) is a powerful tool for monitoring disease activity, progression, and its response to therapy. 18F-FDG PET/computed tomography (PET/CT) of the aorta and carotid arteries has become widely used to assess changes in inflammation in clinical trials. However, the recent advent of hybrid PET/magnetic resonance (PET/MR) scanners has advantages for vascular imaging due to the reduction in radiation exposure and improved soft tissue contrast of MR compared to CT. Important for research and clinical use is an understanding of the scan-rescan repeatability of the PET measurement. While this has been studied for PET/CT, no data is currently available for vascular PET/MR imaging. In this study, we determined the scan-rescan measurement repeatability of 18F-FDG PET/MR in the aorta and carotid arteries was less than 5%, comparable to similar findings for 18F-FDG PET/CT.

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 (SUVmax, MTV, TLG, TLRmax and TLRmean) 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 (SUVmax, TLRmax, TLRmean) and 13 textural indices had an AUC>0.5. Seven groups of highly correlated parameters (r>0.8) were extracted. For PET parameters, SUVmax 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 (ContrastGLCM, LRHGE, SZE and ZLNU) or with one PET parameters (SUVmax, TLRmax) 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.

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.

Assessing the qualitative and quantitative impacts of simple two-class vs multiple tissue-class MR-based attenuation correction for cardiac PET/MR.

BACKGROUND: Hybrid PET/MR imaging has significant potential in cardiology due to its combination of molecular PET imaging and cardiac MR. Multi-tissue-class MR-based attenuation correction (MRAC) is necessary for accurate PET quantification. Moreover, for thoracic PET imaging, respiration is known to lead to misalignments of MRAC and PET data that result in PET artifacts. These factors can be addressed by using multi-echo MR for tissue segmentation and motion-robust or motion-gated acquisitions. However, the combination of these strategies is not routinely available and can be prone to errors. In this study, we examine the qualitative and quantitative impacts of multi-class MRAC compared to a more widely available simple two-class MRAC for cardiac PET/MR. METHODS AND RESULTS: In a cohort of patients with cardiac sarcoidosis, we acquired MRAC data using multi-echo radial gradient-echo MR imaging. Water-fat separation was used to produce attenuation maps with up to 4 tissue classes including water-based soft tissue, fat, lung, and background air. Simultaneously acquired 18F-fluorodeoxyglucose PET data were subsequently reconstructed using each attenuation map separately. PET uptake values were measured in the myocardium and compared between different PET images. The inclusion of lung and subcutaneous fat in the MRAC maps significantly affected the quantification of 18F-fluorodeoxyglucose activity in the myocardium but only moderately altered the appearance of the PET image without introduction of image artifacts. CONCLUSION: Optimal MRAC for cardiac PET/MR applications should include segmentation of all tissues in combination with compensation for the respiratory-related motion of the heart. Simple two-class MRAC is adequate for qualitative clinical assessment.

Good clinical practice recommendations for the use of PET/CT in oncology.

Positron emission tomography/computed tomography (PET/CT) is a nuclear medicine functional imaging technique with proven clinical value in oncology. PET/CT indications are continually evolving with fresh advances made through research. French practice on the use of PET in oncology was framed in recommendations based on Standards-Options-Recommendations methodology and coordinated by the French federation of Comprehensive Cancer Centres (FNLCC). The recommendations were originally issued in 2002 followed by an update in 2003, but since then, a huge number of scientific papers have been published and new tracers have been licenced for market release. The aim of this work is to bring the 2003 version recommendations up to date. For this purpose, a focus group was set up in collaboration with the French Society for Nuclear Medicine (SFMN) to work on developing good clinical practice recommendations. These good clinical practice recommendations have been awarded joint French National Heath Authority (HAS) and French Cancer Institute (INCa) label status-the stamp of methodological approval. The present document is the outcome of comprehensive literature review and rigorous appraisal by a panel of experts, organ specialists, clinical oncologists, surgeons and imaging specialists. These data were also used for the EANM referral guidelines.

Hybrid PET- and MR-driven attenuation correction for enhanced 18F-NaF and 18F-FDG quantification in cardiovascular PET/MR imaging.

BACKGROUND: The standard MR Dixon-based attenuation correction (AC) method in positron emission tomography/magnetic resonance (PET/MR) imaging segments only the air, lung, fat and soft-tissues (4-class), thus neglecting the highly attenuating bone tissues and affecting quantification in bones and adjacent vessels. We sought to address this limitation by utilizing the distinctively high bone uptake rate constant Ki expected from 18F-Sodium Fluoride (18F-NaF) to segment bones from PET data and support 5-class hybrid PET/MR-driven AC for 18F-NaF and 18F-Fluorodeoxyglucose (18F-FDG) PET/MR cardiovascular imaging. METHODS: We introduce 5-class Ki/MR-AC for (i) 18F-NaF studies where the bones are segmented from Patlak Ki images and added as the 5th tissue class to the MR Dixon 4-class AC map. Furthermore, we propose two alternative dual-tracer protocols to permit 5-class Ki/MR-AC for (ii) 18F-FDG-only data, with a streamlined simultaneous administration of 18F-FDG and 18F-NaF at 4:1 ratio (R4:1), or (iii) for 18F-FDG-only or both 18F-FDG and 18F-NaF dual-tracer data, by administering 18F-NaF 90 minutes after an equal 18F-FDG dosage (R1:1). The Ki-driven bone segmentation was validated against computed tomography (CT)-based segmentation in rabbits, followed by PET/MR validation on 108 vertebral bone and carotid wall regions in 16 human volunteers with and without prior indication of carotid atherosclerosis disease (CAD). RESULTS: In rabbits, we observed similar (< 1.2% mean difference) vertebral bone 18F-NaF SUVmean scores when applying 5-class AC with Ki-segmented bone (5-class Ki/CT-AC) vs CT-segmented bone (5-class CT-AC) tissue. Considering the PET data corrected with continuous CT-AC maps as gold-standard, the percentage SUVmean bias was reduced by 17.6% (18F-NaF) and 15.4% (R4:1) with 5-class Ki/CT-AC vs 4-class CT-AC. In humans without prior CAD indication, we reported 17.7% and 20% higher 18F-NaF target-to-background ratio (TBR) at carotid bifurcations wall and vertebral bones, respectively, with 5- vs 4-class AC. In the R4:1 human cohort, the mean 18F-FDG:18F-NaF TBR increased by 12.2% at carotid bifurcations wall and 19.9% at vertebral bones. For the R1:1 cohort of subjects without CAD indication, mean TBR increased by 15.3% (18F-FDG) and 15.5% (18F-NaF) at carotid bifurcations and 21.6% (18F-FDG) and 22.5% (18F-NaF) at vertebral bones. Similar TBR enhancements were observed when applying the proposed AC method to human subjects with prior CAD indication. CONCLUSIONS: Ki-driven bone segmentation and 5-class hybrid PET/MR-driven AC is feasible and can significantly enhance 18F-NaF and 18F-FDG contrast and quantification in bone tissues and carotid walls.

Target definition in salvage postoperative radiotherapy for prostate cancer: 18F-fluorocholine PET/CT assessment of local recurrence.

PURPOSE: Inadequate clinical target volume (CTV) definition is likely to be a major contributing factor to local recurrence (LR) rate after radiotherapy. Our aims were to identify sites of prostate cancer LR in biochemical recurrence post-prostatectomy using 18F-Fluorocholine (18F-FCH) positron emission tomography/computed tomography (PET/CT) and to compare different CTV-delineation guidelines in a cohort of postoperative patients. MATERIAL AND METHODS: Thirty-six patients presenting with LR within the prostatic bed on 18F-FCH PET/CT between 10/2011 and 06/2016 were included in this retrospective study. Median PSA at the time of 18F-FCH PET/CT was 2.7 ng/mL (0.8-9.4) and median PSA doubling time was 11 months (3-28). For each patient, the CTVRTOG, CTVFROGG and CTVEORTC following the corresponding guidelines were outlined and compared. Forty-one LR were delineated using a gradient-based method and the percentage of FCH uptake included in each CTV was evaluated. RESULTS: The anastomosis was the most common recurrence site (52.8%), followed by the retrovesical region (31.7%) and the bladder neck (7%). The median SUV max value was 4.8 (2.3-16.1). The percentage of LR entirely included in the CTVRTOG was not significantly different from that included in the CTVFROGG (84% versus 83%, p = .5). Significantly more recurrences were included in the CTVRTOG volume compared to the CTVEORTC (84% versus 68%, p=.006), due to a better coverage of the bladder neck and retrovesical regions. Six out of 10 relapses occurring in the posterior region of the anastomosis were not covered by any of the CTVs. CONCLUSIONS: In our study, the CTVRTOG and CTVFROGG ensured the best coverage of LR seen on 18F-FCH PET/CT. When outlining the prostatic fossa, greater coverage of the posterior vesico-urethral region may allow better coverage of potential microscopic disease.

Cosmetic Outcome and Chronic Breast Toxicity After Intraoperative Radiation Therapy (IORT) as a Single Modality or as a Boost Using the Intrabeam® Device: A Prospective Study.

PURPOSE: We aim to report our results in terms of chronic toxicities and cosmetic outcomes after intraoperative radiotherapy (IORT) using kV X-rays in women treated for early breast cancer at our institution. METHODS: Patients with early breast carcinoma were recruited between April 2011 and November 2014. After breast-conserving surgery, patients were treated with IORT using the Intrabeam® device. IORT was completed by whole-breast radiotherapy (WBRT) at a dose of 46-50.4 Gy in 23-28 fractions in case of adverse pathologic criteria on the final specimen examination. Skin toxicity was graded using the Late Effects in Normal Tissues-Subjective, Objective, Management and Analytic (LENT-SOMA) scale every 6 months, and cosmetic outcomes were evaluated at 36 months by patient self-evaluation and by two radiation oncologists, on a 1-10 scale. RESULTS: Forty-one women received IORT only and 30 patients received IORT followed by WBRT (IORT + WBRT group). After a median follow-up of 38.9 months, no locoregional or distant recurrence occurred. After IORT only, 2.4% of grade 2 or higher breast fibrosis, and no other grade 2 or higher disease, was observed. In the IORT + WBRT group, grade 2 or higher fibrosis and grade 2 or higher breast retraction were observed in 43.3 and 23.3% of patients, respectively. Objective cosmetic outcomes were very good and significantly better in the IORT-only group compared with the IORT + WBRT group (8.87 vs. 6.96) (p < 0.001). CONCLUSION: IORT using the Intrabeam® is well-tolerated, with very little chronic toxicity and good cosmetic outcome. However, a high rate of grade 2 or higher chronic breast toxicity was observed when IORT had to be completed by WBRT.

Diagnostic performance of FDG PET/CT to detect subclinical HNSCC recurrence 6 months after the end of treatment.

PURPOSE: Posttreatment follow-up for the recurrence of head and neck squamous cell carcinoma (HNSCC) is a diagnostic challenge. Tissue distortion from radiation and surgery can obscure early detection of recurrence by conventional follow-up approaches such as physical examination or conventional imaging. Fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is widely validated for the diagnosis of suspected recurrence. Moreover, we have shown in a previous prospective study the high effectiveness of FDG PET/CT in the assessment of subclinical recurrence 12 months after treatment. The aim of this prospective study was to evaluate the effectiveness of an earlier FDG PET/CT, at 6 months after the end of treatment. METHODS: All patients treated for histologically proven HNSCC from April 2009 to May 2012 at the University Hospital of Brest who did not show any findings suggestive of recurrence at 6 months of their usual follow-up underwent an FDG PET/CT examination. FDG PET/CT findings were correlated with histopathology or imaging follow-up. RESULTS: The study included 116 patients. FDG PET/CT examinations were performed within a mean period ± SD of 5.6 ± 1.8 months after treatment. FDG PET/CT examinations exhibited abnormal FDG uptake in 34 patients and found no suspected recurrence in 82 cases. Of these 82 FDG PET/CT considered as negative, only 1 had a recurrence. Among the 34 positive FDG PET/CT, 22 relapsed whereas 12 did not show evidence of recurrence. The sensitivity and specificity of FDG PET/CT in this study for the diagnosis of occult HNSCC recurrence were 96 (22/23) and 87 % (81/93), respectively. The positive predictive value was 65 % (22/34). The negative predictive value was 99 % (81/82). The overall accuracy was 89 % (103/116). Of the 116 patients, FDG PET/CT highlighted 22 (19 %) subclinical recurrences. CONCLUSION: Our study showed the high effectiveness of FDG PET/CT in the assessment of subclinical HNSCC recurrence 6 months after completion of treatment. These results confirmed that FDG PET/CT is more accurate than conventional follow-up physical examination alone in the assessment of recurrence after previous curative treatment for HNSCC, as we previously demonstrated in patients clinically asymptomatic at 12 months.

Safety of ventilation/perfusion single photon emission computed tomography for pulmonary embolism diagnosis.

PURPOSE: The aim of this management outcome study was to assess the safety of ventilation/perfusion single photon emission computed tomography (V/Q SPECT) for the diagnosis of pulmonary embolism (PE) using for interpretation the criteria proposed in the European Association of Nuclear Medicine (EANM) guidelines for V/Q scintigraphy. METHODS: A total of 393 patients with clinically suspected PE referred to the Nuclear Medicine Department of Brest University Hospital from April 2011 to March 2013, with either a high clinical probability or a low or intermediate clinical probability but positive D-dimer, were retrospectively analysed. V/Q SPECT were interpreted by the attending nuclear medicine physician using a diagnostic cut-off of one segmental or two subsegmental mismatches. The final diagnostic conclusion was established by the physician responsible for patient care, based on clinical symptoms, laboratory test, V/Q SPECT and other imaging procedures performed. Patients in whom PE was deemed absent were not treated with anticoagulants and were followed up for 3 months. RESULTS: Of the 393 patients, the prevalence of PE was 28 %. V/Q SPECT was positive for PE in 110 patients (28 %) and negative in 283 patients (72 %). Of the 110 patients with a positive V/Q SPECT, 78 (71 %) had at least one additional imaging test (computed tomography pulmonary angiography or ultrasound) and the diagnosis of PE was eventually excluded in one patient. Of the 283 patients with a negative V/Q SPECT, 74 (26 %) patients had another test. The diagnosis of PE was finally retained in one patient and excluded in 282 patients. The 3-month thromboembolic risk in the patients not treated with anticoagulants was 1/262: 0.38 % (95 % confidence interval 0.07-2.13). CONCLUSION: A diagnostic management including V/Q SPECT interpreted with a diagnostic cut-off of "one segmental or two subsegmental mismatches" appears safe to exclude PE.

Prognostic value of volumetric parameters measured by 18F-FDG PET/CT in patients with head and neck squamous cell carcinoma.

PURPOSE: The objective of this study was to investigate the value of metabolic tumour volume (MTV) assessed with (18)F-FDG PET/CT in predicting event-free survival (EFS) and overall survival (OS) in patients with head and neck squamous cell carcinoma (HNSCC), and particularly to compare it with more conventional parameters such as maximum standardized uptake value (SUVmax). METHODS: Patients referred to our department for (18)F-FDG PET/CT for staging of HNSCC were prospectively included between February 2009 and March 2011. Each patient was scanned using a Philips Gemini PET/CT system at 1 h after injection. The MTV was calculated semiautomatically for the primary site using methods based on SUV with various thresholds: 3-D contour around voxels equal to or greater than 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0 times SUV, or more than 30%, 40% and 50% of SUVmax. ROC analysis was used to test the statistical significance of the differences among the calculated MTVs. EFS and OS were determined using the Kaplan-Meier method and compared with MTV in univariate and multivariate analyses, including the usual prognostic factors: age, sex, primary site, treatment, SCC histologic grade, AJCC stage, TNM classification, tumour SUVmax and SUVpeak. RESULTS: The study included 80 consecutive patients (70 men, 10 women; mean age 62.4 ± 9.0 years). ROC analysis revealed that pretreatment MTV using a threshold of 5.0 times SUV (MTV5.0) was the best parameter to predict recurrence and death after treatment. In univariate analysis, MTV5.0 >4.9 ml was predictive of poor EFS (p < 0.0001) and poor OS (p < 0.0001). In multivariate, MTV5.0 persisted as an independent predictive factor for EFS (p = 0.011) and OS (p = 0.010), while SUVmax became nonsignificant (p = 0.277 for EFS, p = 0.975 for OS). CONCLUSION: Our results suggest that MTV measured by (18)F-FDG PET/CT has independent prognostic value of in patients with HNSCC, stronger than SUVmax.

Review on radiomic analysis in 18F-fluorodeoxyglucose positron emission tomography for prediction of melanoma outcomes.

Over the past decade, several strategies have revolutionized the clinical management of patients with cutaneous melanoma (CM), including immunotherapy and targeted tyrosine kinase inhibitor (TKI)-based therapies. Indeed, immune checkpoint inhibitors (ICIs), alone or in combination, represent the standard of care for patients with advanced disease without an actionable mutation. Notably BRAF combined with MEK inhibitors represent the therapeutic standard for disease disclosing BRAF mutation. At the same time, FDG PET/CT has become part of the routine staging and evaluation of patients with cutaneous melanoma. There is growing interest in using FDG PET/CT measurements to predict response to ICI therapy and/or target therapy. While semiquantitative values such as standardized uptake value (SUV) are limited for predicting outcome, new measures including tumor metabolic volume, total lesion glycolysis and radiomics seem promising as potential imaging biomarkers for nuclear medicine. The aim of this review, prepared by an interdisciplinary group of experts, is to take stock of the current literature on radiomics approaches that could improve outcomes in CM.

Case-control study of the characteristics and risk factors of hot clot artefacts on 18F-FDG PET/CT.

INTRODUCTION: The pulmonary Hot Clot artifact (HCa) on 18F-FDG PET/CT is a poorly understood phenomenon, corresponding to the presence of a focal tracer uptake without anatomical lesion on combined CTscan. The hypothesis proposed in the literature is of microembolic origin. Our objectives were to determine the incidence of HCa, to analyze its characteristics and to identify associated factors. METHODS: All 18F-FDG PET/CT retrieved reports containing the keywords (artifact/vascular adhesion/no morphological abnormality) during the period June 2021-2023 at Brest University Hospital were reviewed for HCa. Each case was associated with 2 control patients (same daily work-list). The anatomical and metabolic characteristics of HCa were analyzed. Factors related to FDG preparation/administration, patient and vascular history were investigated. Case-control differences between variables were tested using Chi-2 test and OR (qualitative) or Student's t-test (quantitative). RESULTS: Of the 22,671 18F-FDG PET/CT performed over 2 years, 211 patients (0.94%) showed HCa. The focus was single in 97.6%, peripheral in 75.3%, and located independently in the right or left lung (51.1% vs. 48.9%). Mean ± SD values for SUVmax, SUVmean, MTV and TLG were 11.3 ± 16.5, 5.1 ± 5.0, 0.3 ± 0.3 ml and 1.5 ± 2.1 g respectively. The presence of vascular adhesion (p < 0.001), patient age (p = 0.002) and proximal venous access (p = 0.001) were statistically associated with the presence of HCa. CONCLUSION: HCa is a real but rare phenomenon (incidence around 1%), mostly unique, intense, small in volume (< 1 ml), and associated with the presence of vascular FDG uptake, confirming the hypothesis of a microembolic origin due to probable vein wall trauma at the injection site.

Diagnostic Performance of 18F-FDG PET/CT According to Delay After Treatment to Detect Subclinical Recurrence of Head and Neck Squamous Cell Carcinoma.

Head and neck squamous cell carcinoma (HNSCC) remains a malignancy with high rates of locoregional recurrence and poor prognosis for recurrent cases. Early detection of subclinical lesions is challenging but critical for effective patient management. Imaging surveillance after treatment, particularly 18F-FDG PET/CT, has shown promise in the diagnosis of HNSCC recurrence. The aim was to evaluate the diagnostic performance of 18F-FDG PET/CT according to delay after treatment in detecting subclinical recurrence (SCR) in HNSCC patients. Methods: In this retrospective study, all 18F-FDG PET/CT scans were performed at a single center. All adults with histologically proven HNSCC who were treated with curative intent between January 1, 2006, and December 31, 2021, were included. They had a normal clinical examination before each scan. Patients who underwent an intensive follow-up strategy after treatment had 18F-FDG PET/CT with an intravenous contrast agent at 3-6 mo and annually thereafter for 5 y. The primary endpoint was diagnostic performance (positive and negative predictive values, sensitivity, specificity, and accuracy). Results: In total, 2,566 18F-FDG PET/CT scans were performed among 852 patients, with an average of 3 scans per patient. The overall diagnostic performance measures were as follows: positive predictive value (88%), negative predictive value (98%), sensitivity (98%), specificity (89%), and accuracy (93%). There were no significant differences in diagnostic performance over time. The scans detected 126 cases of SCR (14.8%) and 118 cases of metachronous cancer (13.8%). The incidence of SCR decreased over time, with the highest detection rate in the first 2 y after treatment. Positive predictive value improved over time, reaching 90% for the digital Vision 600 system (third period) compared with 76% for the analog Gemini GXLi system (first period, P < 0.001). Multivariate analysis identified advanced stage, high body mass index, and initial PET/CT upstaging as predictive factors for detection of SCR. Conclusion: Our study demonstrates that 18F-FDG PET/CT has high diagnostic performance in detecting SCR during follow-up after treatment of HNSCC, especially in the first 2 y. Advanced tumor stage, initial PET/CT upstaging, and high body mass index were associated with a higher likelihood of SCR detection. The routine use of 18F-FDG PET/CT during follow-up seems justified for patients with HNSCC.

Specific locations of myocardial inflammation and fibrosis are associated with higher risk of events in cardiac sarcoidosis.

BACKGROUND: 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/magnetic resonance (MR) can identify inflammation and fibrosis, which are high-risk features in cardiac sarcoidosis. OBJECTIVE: The purpose of this study was to evaluate whether the involvement of certain myocardial segments is associated with higher risk compared to others. METHODS: One hundred twenty-four patients with suspected clinical sarcoidosis underwent 18F-FDG-PET/MR. Late gadolinium enhancement (LGE) and focal 18F-FDG uptake were evaluated globally and in the 16 myocardial segments. Presence of LGE was defined when the percentage of LGE exceeded 5.7% globally (relative to myocardial volume) and in each myocardial segment. Patients were followed up for 5.5 years. Events were defined as ventricular arrhythmia (VA) (including sustained ventricular tachycardia, ventricular fibrillation, and appropriate implantable cardioverter-defibrillator discharge), heart failure hospitalization, or all-cause death. RESULTS: Mean age was 57.1 ± 8.9 years, and 39.5% were female. Twenty-two patients (17.6%) had an event during follow-up, and 9 (7.2%) presented with VA. LGE and 18F-FDG uptake were more frequent in patients with than without events (36.4% vs 7.8%, P = .001). Presence of LGE and 18F-FDG in the basal anterior segment were independent predictors for events after adjustment for left ventricular ejection fraction and relative enhanced volume (LGE: odds ratio [1.2-92.4], P = .034;18F-FDG: odds ratio 5.5 [1.1-27.5], P = .038). LGE presence in basal to mid-anterior, mid-anteroseptal, and basal to mid-inferoseptal segments was an independent predictor of VA. Presence of 18F-FDG in basal to mid-anterior, mid-inferoseptal and mid-inferior segments was an independent predictor of VA. CONCLUSION: Involvement of specific myocardial segments, particularly basal to mid-anterior and mid-septal segments, is associated with higher rates of events in patients with suspected cardiac sarcoidosis.

Hybrid Magnetic Resonance Positron Emission Tomography Is Associated With Cardiac-Related Outcomes in Cardiac Sarcoidosis.

BACKGROUND: Imaging with late gadolinium enhancement (LGE) magnetic resonance (MR) and 18F-fluorodeoxyglucose (18F-FDG) PET allows complementary assessment of myocardial injury and disease activity and has shown promise for improved characterization of active cardiac sarcoidosis (CS) based on the combined positive imaging outcome, MR(+)PET(+). OBJECTIVES: This study aims to evaluate qualitative and quantitative assessments of hybrid MR/PET imaging in CS and to evaluate its association with cardiac-related outcomes. METHODS: A total of 148 patients with suspected CS underwent hybrid MR/PET imaging. Patients were classified based on the presence/absence of LGE (MR+/MR-), presence/absence of 18F-FDG (PET+/PET-), and pattern of 18F-FDG uptake (focal/diffuse) into the following categories: MR(+)PET(+)FOCAL, MR(+)PET(+)DIFFUSE, MR(+)PET(-), MR(-)PET(+)FOCAL, MR(-)PET(+)DIFFUSE, MR(-)PET(-). Further analysis classified MR positivity based on %LGE exceeding 5.7% as MR(+/-)5.7%. Quantitative values of standard uptake value, target-to-background ratio, target-to-normal-myocardium ratio (TNMRmax), and T2 were measured. The primary clinical endpoint was met by the occurrence of cardiac arrest, ventricular tachycardia, or secondary prevention implantable cardioverter-defibrillator (ICD) before the end of the study. The secondary endpoint was met by any of the primary endpoint criteria plus heart failure or heart block. MR/PET imaging results were compared between those meeting or not meeting the clinical endpoints. RESULTS: Patients designated MR(+)5.7%PET(+)FOCAL had increased odds of meeting the primary clinical endpoint compared to those with all other imaging classifications (unadjusted OR: 9.2 [95% CI: 3.0-28.7]; P = 0.0001), which was higher than the odds based on MR or PET alone. TNMRmax achieved an area under the receiver-operating characteristic curve of 0.90 for separating MR(+)PET(+)FOCAL from non-MR(+)PET(+)FOCAL, and 0.77 for separating those reaching the clinical endpoint from those not reaching the clinical endpoint. CONCLUSIONS: Hybrid MR/PET image-based classification of CS was statistically associated with clinical outcomes in CS. TNMRmax had modest sensitivity and specificity for quantifying the imaging-based classification MR(+)PET(+)FOCAL and was associated with outcomes. Use of combined MR and PET image-based classification may have use in prognostication and treatment management in CS.

Incidental Finding of a Tongue Schwannoma Mimicking Local Recurrence of Squamous Cell Carcinoma on a Systematic Follow-up 18F-FDG PET/CT.

ABSTRACT: Schwannomas are usually benign, rare, and slow-growing nerve sheath tumor composed of Schwann cells. They develop in the head and neck area in approximately 25% to 40% of cases, of which 1% in the oral cavity, where the tongue remains the preferred site. Malignant transformation occurs in approximately 8% to 10% cases. We report a unique case of a histologically proven FDG-avid schwannoma of the left mobile portion of the tongue, showing an 18F-FDG avidity on PET/CT, which was a false-positive result for local recurrence in a patient followed for squamous cell carcinoma.

Clinical application of a population-based input function (PBIF) for a shortened dynamic whole-body FDG-PET/CT protocol in patients with metastatic melanoma treated by immunotherapy.

BACKGROUND: The aim was to investigate the feasibility of a shortened dynamic whole-body (dWB) FDG-PET/CT protocol and Patlak imaging using a population-based input function (PBIF), instead of an image-derived input function (IDIF) across the 60-min post-injection period, and study its effect on the FDG influx rate (Ki) quantification in patients with metastatic melanoma (MM) undergoing immunotherapy. METHODS: Thirty-seven patients were enrolled, including a PBIF modeling group (n = 17) and an independent validation cohort (n = 20) of MM from the ongoing prospective IMMUNOPET2 trial. All dWB-PET data were acquired on Vision 600 PET/CT systems. The PBIF was fitted using a Feng's 4-compartments model and scaled to the individual IDIF tail's section within the shortened acquisition time. The area under the curve (AUC) of PBIFs was compared to respective IDIFs AUC within 9 shortened time windows (TW) in terms of linear correlation (R2) and Bland-Altman tests. Ki metrics calculated with PBIF vs IDIF on 8 organs with physiological tracer uptake, 44 tumoral lesions of MM and 11 immune-induced inflammatory sites of pseudo-progression disease were also compared (Mann-Whitney test). RESULTS: The mean ± SD relative AUC bias was calculated at 0.5 ± 3.8% (R2 = 0.961, AUCPBIF = 1.007 × AUCIDIF). In terms of optimal use in routine practice and statistical results, the 5th-7th pass (R2 = 0.999 for both Ki mean and Ki max) and 5th-8th pass (mean ± SD bias = - 4.9 ± 6.5% for Ki mean and - 4.8% ± 5.6% for Ki max) windows were selected. There was no significant difference in Ki values from PBIF5_7 vs IDIF5_7 for physiological uptakes (p > 0.05) as well as for tumor lesions (mean ± SD Ki IDIF5_7 3.07 ± 3.27 vs Ki PBIF5_7 2.86 ± 2.96 100ml/ml/min, p = 0.586) and for inflammatory sites (mean ± SD Ki IDIF5_7 1.13 ± 0.59 vs Ki PBIF5_7 1.13 ± 0.55 100ml/ml/min, p = 0.98). CONCLUSION: Our study showed the feasibility of a shortened dWB-PET imaging protocol with a PBIF approach, allowing to reduce acquisition duration from 70 to 20 min with reasonable bias. These findings open perspectives for its clinical use in routine practice such as treatment response assessment in oncology.