924: In-111 Octreoscan scintigraphy quantification with xSPECT: first report on data of tumoral and non-tumoral SUV range

Objectives: With the latest SPECT scanners, it is possible to quantitate radioisotope activity precisely. We aimed at reporting the values of SUVmax and SUVmean from first data from quantitative In-111 Octreoscan scintigraphy using x-SPECT quantification technique. Methods: We measured mean±SD and 95% confidence interval (95%CI) of SUVmax and SUVmean in nine patients undergoing quantitative In-111 Octreoscan scintigraphy for neuroendocrine tumor assessment with xSPECT (Intevo, Siemens). ROIs of non-tumoral abdominal organs, primary and metastatic sites were calculated on both 2-hour and 24-hour acquisitions. ROIs of hepatic, splenic and digestive organs were at least 3cm3; pancreas was divided into head and body-tail regions. Results: SUVmax and SUVmean (g/mL) measured at 2- and 24-hour post-tracer injection acquisitions were, respectively: liver (3.4±1; 2.2±0.7; 3.3±1.2; 1.9±0.7), spleen (11.5±4.6; 8.1±3.3; 9±4.7; 6.3±3.2), digestive tract (2.0±0.9; 1.1 ± 0.5; 2.8 ± 1.8; 1.7 ± 1.1), pancreatic head (2.1±0.6; 1.4±0.5; 2±1.4; 1.3±0.9), pancreatic body-tail (1.8±0.7; 1.2±0.5; 1.5±0.6; 1.0±0.4), primary site (9.6±5.7; 6±3.7; 5.8±3.4 ; 3.6±2.0), metastases (18.3±12; 11.2±7.9; 10.3±3.2; 6.1±2.1). Conclusion: We found a clear difference in the measured activity of tumoral and non-tumoral tissue. Both SUV max and SUVmean of primary and metastatic sites halved 24-hours after tracer injection but remained higher than mean splenic uptake. Digestive activity increased with time, but remained lower than normal hepatic uptake. The knowledge of SUV range and time variation might help understanding the nature of SPECT abnormalities. Research Support: non

Primary Chronic Sclerosing Osteomyelitis: A New Diagnostic Tool

Aims: Primary chronic sclerosing osteomyelitis is a rare and complex pathology and remains a diagnostic and therapeutic challenge. Our aim is to show our experience with a new diagnostic tool. Material and Methods: Four patients aged from 26 to 67 were referred to the department of oral and maxillofacial surgery of University Hospital CHUV in Lausanne between January 2010 and December 2018 for chronic mandibular pain without infectious signs nor symptoms. All patients underwent three-phase bone scintigraphy and anti-granulocyte antibody scintigraphy. Results: Three-phase bone scintigraphy demonstrated radiotracer uptake at the zone of pain, whereas anti-granulocyte antibody scintigraphy showed no uptake, thus rendering an infectious origin unlikely. Conclusion: A combination of the two different scintigraphies should be considered in order to guide the clinician in the diagnosis of primary chronic sclerosing osteomyelitis, thus preventing patients from undergoing unnecessary imagery and useless treatment, and also allowing an early diagnosis

Response of Brain and Meningeal Metastases to Trastuzumab-Deruxtecan in a Patient with HER2-Low Breast Cancer: A Case Report

Nervous system metastases (CNSm) are late events associated with poor outcomes in endocrine-sensitive HER2-negative breast cancer (BC) patients, especially in the presence of leptomeningeal disease (LMD). Effective treatments are extremely limited in this setting. The antibody-drug conjugate, trastuzumab-deruxtecan (T-DXd), which combines the anti-HER2 antibody trastuzumab with a topoisomerase type 1 inhibitor, showed high efficacy not only against HER2-positive but also HER2-low metastatic BCs, expressing HER2 at a lower level. To the best of our knowledge, this is the first report of a patient with metastatic endocrine-sensitive HER2-low BC suffering from BMs associated with LMD and sustained disease control when treated with T-DXd. Several recent case series have reported the activity of T-DXd in patients with HER2-positive disease and brain metastases or LMD, but none in HER2-low patients. This case is particularly relevant since more than 50% of BCs are HER2-low

Reproducibility of lung cancer radiomics features extracted from data-driven respiratory gating and free-breathing flow imaging in [18F]-FDG PET/CT

BACKGROUND: Quality and reproducibility of radiomics studies are essential requirements for the standardisation of radiomics models. As recent data-driven respiratory gating (DDG) [(18)F]-FDG has shown superior diagnostic performance in lung cancer, we evaluated the impact of DDG on the reproducibility of radiomics features derived from [(18)F]-FDG PET/CT in comparison to free-breathing flow (FB) imaging. METHODS: Twenty four lung nodules from 20 patients were delineated. Radiomics features were derived on FB flow PET/CT and on the corresponding DDG reconstruction using the QuantImage v2 platform. Lin’s concordance factor (C(b)) and the mean difference percentage (DIFF%) were calculated for each radiomics feature using the delineated nodules which were also classified by anatomical localisation and volume. Non-reproducible radiomics features were defined as having a bias correction factor C(b)   10. RESULTS: In total 141 features were computed on each concordance analysis, 10 of which were non-reproducible on all pulmonary lesions. Those were first-order features from Laplacian of Gaussian (LoG)-filtered images (sigma = 1 mm): Energy, Kurtosis, Minimum, Range, Root Mean Squared, Skewness and Variance; Texture features from Gray Level Cooccurence Matrix (GLCM): Cluster Prominence and Difference Variance; First-order Standardised Uptake Value (SUV) feature: Kurtosis. Pulmonary lesions located in the superior lobes had only stable radiomics features, the ones from the lower parts had 25 non-reproducible radiomics features. Pulmonary lesions with a greater size (defined as long axis length > median) showed a higher reproducibility (9 non-reproducible features) than smaller ones (20 non-reproducible features). CONCLUSION: Calculated on all pulmonary lesions, 131 out of 141 radiomics features can be used interchangeably between DDG and FB PET/CT acquisitions. Radiomics features derived from pulmonary lesions located inferior to the superior lobes are subject to greater variability as well as pulmonary lesions of smaller size. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41824-022-00153-2