Increased lesion detectability in patients with locally advanced breast cancer-A pilot study using dynamic whole-body [18F]FDG PET/CT.

BACKGROUND: Accurate diagnosis of axillary lymph node (ALN) metastases is essential for prognosis and treatment planning in breast cancer. Evaluation of ALN is done by ultrasound, which is limited by inter-operator variability, and by sentinel lymph node biopsy and/or ALN dissection, none of which are without risks and/or long-term complications. It is known that conventional 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) has limited sensitivity for ALN metastases. However, a recently developed dynamic whole-body (D-WB) [18F]FDG PET/CT scanning protocol, allowing for imaging of tissue [18F]FDG metabolic rate (MRFDG), has been shown to have the potential to increase lesion detectability. The study purpose was to examine detectability of malignant lesions in D-WB [18F]FDG PET/CT compared to conventional [18F]FDG PET/CT. RESULTS: This study prospectively included ten women with locally advanced breast cancer who were referred for an [18F]FDG PET/CT as part of their diagnostic work-up. They all underwent D-WB [18F]FDG PET/CT, consisting of a 6 min single bed dynamic scan over the chest region started at the time of tracer injection, a 64 min dynamic WB PET scan consisting of 16 continuous bed motion passes, and finally a contrast-enhanced CT scan, with generation of MRFDG parametric images. Lesion visibility was assessed by tumor-to-background and contrast-to-noise ratios using volumes of interest isocontouring tumors with a set limit of 50% of SUVmax and background volumes placed in the vicinity of tumors. Lesion visibility was best in the MRFDG images, with target-to-background values 2.28 (95% CI: 2.04-2.54) times higher than target-to-background values in SUV images, and contrast-to-noise values 1.23 (95% CI: 1.12-1.35) times higher than contrast-to-noise values in SUV images. Furthermore, five imaging experts visually assessed the images and three additional suspicious lesions were found in the MRFDG images compared to SUV images; one suspicious ALN, one suspicious parasternal lymph node, and one suspicious lesion located in the pelvic bone. CONCLUSIONS: D-WB [18F]FDG PET/CT with MRFDG images show potential for improved lesion detectability compared to conventional SUV images in locally advanced breast cancer. Further validation in larger cohorts is needed. CLINICAL TRIAL REGISTRATION: The trial is registered in clinicaltrials.gov, NCT05110443, https://www. CLINICALTRIALS: gov/study/NCT05110443?term=NCT05110443&rank=1 .

The impact of CHOP versus bendamustine on bone mineral density in patients with indolent lymphoma enrolled in the GALLIUM study.

Standard CHOP treatment includes a high cumulative dose of prednisone, and studies have shown increased fracture risk following CHOP. It is unclear whether reductions in bone mineral density (BMD) are caused by glucocorticoids or by the combination with chemotherapy. Our objective was to determine the effect of obinutuzumab (G)/rituximab (R)-bendamustine versus G/R-CHOP on BMD in follicular lymphoma patients. Patients in this GALLIUM post hoc study were ≥60 years old and in complete remission at induction treatment completion (ITC), following treatment with G or R in combination with bendamustine or CHOP. To assess BMD, Hounsfield units (HU) were measured in lumbar vertebra L1 on annual computed tomography. Furthermore, vertebral compression fractures were recorded. Of 173 patients included, 59 (34%) received CHOP and 114 (66%) received bendamustine. At baseline, there was no difference in HU between groups. The mean HU decrease from baseline to ITC was 27.8 after CHOP and 17.3 after bendamustine, corresponding to a difference of 10.4 (95% CI: 3.2-17.6). Vertebral fractures were recorded in 5/59 patients receiving CHOP and in 2/114 receiving bendamustine. CHOP was associated with a significant greater decrease in BMD and more frequent fractures. These results suggest that prophylaxis against BMD loss should be considered.

Inclusion of Metabolic Tumor Volume in Prognostic Models of Bone and Soft Tissue Sarcoma Increases the Prognostic Value.

Sarcomas are rare and have a high mortality rate. Further prognostic classification, with readily available parameters, is warranted, and several studies have examined circulating biomarkers and PET parameters separately. This single-site, retrospective study aimed to examine the prognostic values of several scoring systems in combination with PET parameters. We included 148 patients with sarcoma, who were treated and scanned at Aarhus University Hospital from 1 January 2016 to 31 December 2019. The Akaike information criterion and Harrell's concordance index were used to evaluate whether the PET parameters added prognostic information to existing prognostic models using circulating biomarkers. Of the PET parameters, metabolic tumor volume (MTV) performed best, and when combined with the existing prognostic models, the prognostic value improved in all models. Backward stepwise selection was used to create a new model, SBSpib, which included albumin, lymphocytes, and one PET parameter, MTV. It has scores ranging from zero to three and increasing hazard ratios; HR = 4.83 (1.02-22.75) for group one, HR = 7.40 (1.6-33.42) for group two, and HR = 17.32 (3.45-86.93) for group three. Consequently, implementing PET parameters in prognostic models improved the prognostic value. SBSpib is a new prognostic model that includes both circulating biomarkers and PET parameters; however, validation in another sarcoma cohort is warranted.

Absent 18F-FDG Uptake in the Brain-Unsuspected Brain Death.

Brain death is the complete, irreversible cessation of brain function, including the capacity for brainstem, respiratory, and vegetative activities. It is a clinical diagnosis that can be supplemented with brain perfusion imaging. Absent cerebral blood flow can be visualized with CT angiography or perfusion scintigraphy. F-FDG PET/CT, visualizing glucose uptake, is another approach that has been shown to indicate brain death in small case series. We here present a case with unsuspected absent F-FDG uptake and thus no metabolic activity, in the brain. The patient was declared brain dead later the same day.

A comparative study of standardized quantitative and visual assessment for predicting tumor volume and outcome in newly diagnosed diffuse large B-cell lymphoma staged with 18F-FDG PET/CT.

BACKGROUND: Semi-automated quantitative measurement of metabolic tumor volume (MTV) for prognosis in diffuse large B-Cell lymphoma (DLBCL) has gained considerable interest lately. However, simple tumor volume measures may be inadequate for assessment of prognosis in DLBCL as other characteristics such as growth pattern and metabolic heterogeneity may be just as important. In addition, MTV measurements require delineation of tumor lesions by semi-automated software, which can be time-consuming. We hypothesized that a simple visual assessment of tumor volume performs as well as standardized MTV measurements in DLBCL prognostication. MATERIALS AND METHODS: Quantitative and visual analyses of pre-therapy 18F-FDG PET/CT scans in 118 patients with newly diagnosed DLBCL were conducted. Quantitative analyses were performed using Hermes TumourFinder® to obtain MTV2.5 (SUV 2.5 cut-off) and MTV41 (41% SUVmax isocontour cut-off). Visual assessments included a binary prediction (good/poor prognosis) as well as tumor burden based on a visual analog scale (MTVVAS) and an estimated volume (eMTV). Three experienced nuclear medicine physicians who were blinded to clinical outcome performed visual evaluations. Progression-free survival was evaluated by Kaplan-Meier curves and log-rank test. Inter-observer variability was evaluated by Fleiss' kappa for multiple observers. RESULTS: In the quantitative analysis, a ROC-determined MTV2.5 cut-off (log-rank p = 0.11) seemed to outperform MTV41 (log-rank p = 0.76) for PFS prediction. TLG2.5 (log-rank p = 0.14) and TLG41 (log-rank p = 0.34) were not associated with outcomes. By visual analysis, all three reviewers were able to stratify patients into good/poor prognosis (reviewer A log-rank p = 0.002, reviewer B log-rank p = 0.016, and reviewer C log-rank p = 0.012) with fair inter-observer agreement (Fleiss' kappa 0.47). MTVVAS and eMTV were not consistently correlated with the outcome. CONCLUSION: Predictions of outcome after first-line treatment for DLBCL were surprisingly good when left to the unsupervised, subjective judgment of experienced readers of lymphoma 18F-FDG-PET/CT. The study highlights the importance of non-standardized clinical judgments and shows potential loss of valuable prognostic information when relying solely on semi-automated MTV measurements.

68Ga-PSMA Uptake in Middle Lobe Syndrome.

Prostate cancer cells have abundant expression of the cell surface protein prostate-specific membrane antigen (PSMA). In recent years, PET radioligands detecting this protein has therefore gained substantial interest in prostate cancer staging. It turned out that PSMA expression can be evident in both malignant and benign lesions, and we have previously reported that pulmonary opacities and bronchiectasis can be avid on Ga-PSMA PET/CT. Here, we present a case with Ga-PSMA accumulation in nonobstructive middle lobe syndrome, which further indicate that benign changes in the lungs may be falsely interpreted as malignant disease.