Body PET Research Articles

Isolated Intracranial Rosai-Dorfman Disease: A Diagnostic Challenge

Rosai-Dorfman disease (RDD) is a benign condition characterized by abnormal proliferation of white blood cells called histiocytes and an uncommon biological process called emperipolesis, in which a living cell penetrates inside another living cell. Central nervous system involvement in RDD is extremely rare. We report one such rare case of 47-year- old man who presented with right sided focal seizure from 1 year. MRI Brain showed a dural based lesion. On the basis of clinical presentation and radiological findings initial diagnosis made was of en plaque meningioma. Gross total resection of lesion was performed. Initial histopathological diagnosis was of IgG4 related HPM. Post surgery there was significant improvement in patients clinical condition. Intensity of seizure episodes were reduced. However due to persistence of right sided focal seizures, tissue blocks were reviewed and diagnosis of intracranial Rosai-Dorfman disease was made. Upon which further hematologist opinion was taken and whole body PET CT was done which showed solitary uptake in brain. It was observed that characteristic feature of RDD emperipolesis is sometimes masked by storiform fibrosis and lymphocytic infiltration leading to misdiagnosis. Therefore close follow up is required, in case of persistence of symptoms tissue blocks should be reviewed and possibility of intracranial Rosai-Dorfman disease should be considered while dealing with dural based lesions.

Central nervous system solitary fibrous tumors: Case series in accordance with the WHO 2021 reclassification. Framework for patient surveillance.

Solitary fibrous tumors (SFTs) are a rare type of mesenchymal tumors. The World Health Organization reclassified SFTs in 2021. Currently, guidelines concerning treatment and follow-up are lacking. We performed a retrospective case series with reclassification of SFTs, according to the most recent WHO classification, to explore tumor-behavior. The purpose is to build a framework for long-term patient surveillance. A retrospective case study was performed according to the PROCESS guidelines. Inclusion criteria were: patients operated on between 2013 and 2023 in two neurosurgical centers with the diagnosis of 'hemangiopericytoma' or SFT on histopathological stains. Patients were excluded if the original stains of the primary tumor were unavailable. The following demographic, radiologic and therapeutic parameters were included in the review: age, sex, original and reclassified anatomopathological diagnosis, location, extent of resection, use of postoperative radiotherapy, location of and time to recurrence, location of-and time to metastasis, and survival. Histological material was re-examined by experienced neuropathologists. Ten patients were identified with a solitary fibrous tumor of the central nervous system (CNS) (three females) between 2013 and 2023. Age at diagnosis ranged from 38 up to 81. Eight patients were treated by gross total resection (GTR) and postoperative radiotherapy (RT) was applied in five cases. Initial WHO grading consisted of three grade I, two grade II, and six grade III lesions. Reclassification according to the WHO 2021 classification of CNS tumors resulted in seven reclassifications, all towards a lower grade. Four patients showed local recurrence, six to eight years after diagnosis, and five patients developed systemic metastases, nine to 13 years after diagnosis. Although rare, SFT should be included in the differential diagnosis of intracranial tumors with extra-axial growth patterns. The current histological grade according to the WHO 2021 does not seem to account for local recurrence rate or systemic metastasis. When a solitary fibrous tumor is presumed, gross total resection is the recommended treatment. Lifelong patient follow-up is necessary due to the risk of delayed recurrence and distant metastasis, even after gross-total resection. We would advocate for the use of CT thorax-abdomen or full body PET in the detection of systemic metastases at diagnosis and during follow-up, however optimal intervals remain unclear.

Performance measurements of Total Body PET scanner simulations using the Geant4 toolkit

Total-Body PET (TB PET) is a novel imaging modality that can image the whole body in a single scan. It has increased sensitivity, improved spatial resolution, reduced imaging times compared to conventional clinical PET scanners, and has the potential to detect smaller lesions and multiorgan diseases. Commercially available TB PET scanners include the Siemens Biograph Vision Quadra [1] and the United Imaging uEXPLORER [2]. This study uses the Geant4 toolkit [3] to create a simulation model of two different TB PET detector geometries; Siemens Biograph Vision Quadra and uEXPLORER. Analysis of simulated data and performance measurements were carried out in Python. The study follows the NEMA NU-2 2018 standard [4]. The simulation was used to explore the effect of different scintillator crystals and evaluates the count rate performance and the sensitivity of the scanner. The simulated data was compared to published experimental data from Siemens and Explorer. Good agreement between the count rates of simulated and experimental data was observed for both geometries. The simulated Siemens Quadra measured a system sensitivity value of 178.6 cps/kBq showing a 2% difference compared to the experimental data of 175.3 cps/kBq for LSO crystals. Axial sensitivity profiles plotted also match well. The comparison of different scintillators showed that BGO performs best as it has the highest peak NECR, thus good signal-to-noise ratio. LSO and LYSO also perform well and their physical properties are similar. NaI and CsI exhibit the worst performance; with low true count rates and the random count rates increased almost linearly with activity concentration. Our simulations compared well against experimental data, allowing us to test further scintillator materials and radioisotopes. After implementing image reconstruction and relevant corrections, this simulation can be used for validation of various research ideas in the future. Please click on the 'PDF' for the full abstract!

Using total-body PET to investigate relationships between excretory organs time activity curves and the metabolite fraction for [18F]SynVesT-1

Accurate quantification of dynamic PET data using kinetic modelling requires assessment of the metabolism of the tracer to obtain the quantity of unchanged parent tracer in the blood. Several image derived input functions methods have been demonstrated to be effective for kinetic modelling; however, currently no image derived metabolite correction method exists. Finding an image derived metabolite correction would remove the need for invasive blood sampling. This study uses 7 full body 18F-SynVesT-1 total body mouse scans. Initially, the time activity curves (TACs) for a range of organs including the liver, kidney and bladder were studied. Factor analysis (FA) was investigated to accurately separate contributions from the kidney – cortex, medulla and collecting duct. Following this, the relationships between each of the organ TACs and the parent plasma fraction (PPf) was investigated. FA analysis successfully discriminates between contributions from the cortex, medulla and collecting duct of the kidneys. In the context of total body scans, FA removes the need for manual drawing of volumes of interest allowing for more consistency amongst studies. By separating out these regions, a relationship between the kidney medulla and the metabolites also came to light. In addition, the average of the seven bladder time activity curves against the plasma parent fraction [Figure 1] shows a potential relationship between the excretion of the tracer and its metabolism. Combining excretory organ relationships with the parent fraction and potentially liver data opens the possibility for a model to be produced to fit a metabolite curve when we have access to a total body PET scan. While this research is in its early stages, it has shown relationships between excretory organ TACs and the metabolite fraction. This has the potential to allow for metabolite correction models to be created directly from the image data. Model architectures are under investigation. Please click on the 'PDF' for the full abstract!

6981 Atypical hypoglycemia in a teenage boy with prediabetes

Abstract Disclosure: N. Shahid: None. C. salgado: None. N. Gurtunca: None. Background: Hypoglycemia in teenagers is seen less commonly than in younger children. Overweight children with prediabetes presenting with hypoglycemia symptoms are often considered to have reactive post-prandial hypoglycemia due to the degree of hyperinsulinemia with insulin resistance seen in these children. We present a 13-year-old boy with prediabetes, who presented with episodes of altered mental status and was found to have hypoglycemia due to a solitary insulin secreting tumor. Case presentation: A 13-yr old boy with pre-diabetes presented to the ER with altered consciousness and non-ketotic, non-acidotic hypoglycemia [25 mg/dl] & trace ketonuria in the setting of Influenza A infection. Weight and BMI above the 99th%ile and acanthosis nigricans in the skin creases. No access to oral hypoglycemic agents. Urine toxicology was negative. EEG was normal. Euglycemia and level of consciousness restored after IV dextrose & this was considered a possible hypoglycemic seizure episode secondary to poor oral intake. 4 months later he had another episode of altered mental status, jittery movements and was found to be hypoglycemic [41 mg/dl]. He was admitted for further workup of recurrent hypoglycemia. Adrenal insufficiency was ruled out and a diagnostic fast was started. After 15 hours, he developed non-ketotic hypoglycemia [<50 mg/dl]. Critical sample [Table 1] and Glucagon challenge [Table 2] at the termination of the fast confirmed hyperinsulinemic hypoglycemia. Given the unusual age and presentation, an MRI abdomen was done which showed a 1.6 cm lesion in the pancreatic body [Fig 1]. Dotatate whole body PET scan confirmed the insulinoma with no evidence of nodal or distant metastasis [Fig 2]. He underwent surgical enucleation of the insulinoma. Intraoperative secretin showed no evidence of pancreatic duct dilatation or leakage. Hereditary endocrine tumor panel including multiple endocrine neoplasia [MEN] gene analysis was negative. The postoperative course was complicated by a persistent pancreatic leak and pancreatitis eventually requiring an ERCP and stent placement 2 months post operatively. Conclusion: Insulinomas are very rare neuroendocrine tumors in pediatric population, with a prevalence of one in 250,000 and median age at presentation of 45-50 years. About 90% insulinomas are benign and less than 10% are associated with MEN-1 syndrome. Chronic hypoglycemia irrespective of the underlying insulin resistance of prediabetes can be seen with insulinoma and can cause hypoglycemia unawareness as seen in our patient. This has also been reported in literature to be misdiagnosed as refractory epilepsy or psychiatric disorders. Hypoglycemic symptoms at any age should be promptly worked up. Ruling out associated neuroendocrine hereditary tumor syndromes is crucial and prognosis of benign solitary insulinomas after surgical removal is mostly favorable. Presentation: 6/3/2024

A Comprehensive Analysis of Metastatic Disease following Surgery for Clinically Localized Cutaneous Melanoma.

The NCCN considers "baseline staging" (whole body CT or PET scan +/- brain MRI) for all asymptomatic melanoma patients with a positive sentinel lymph node biopsy. The true yield of these workups is unknown. We created cohorts of adult malignant melanoma patients, using the National Cancer Database (2012-2020) to mimic three common scenarios: (1) clinically node negative, with positive sentinel lymph node(s) (SLNB[+]); (2) clinically node negative, with negative sentinel lymph node(s) (SLNB[-]); (3) clinically node positive with confirmed lymph node metastases (cN[+] and pN[+]). Multivariable regression, supervised decision trees, and nomograms were constructed to assess the risk of metastases based on key features. 10,371 patients were SLNB[+], 55,172 were SLNB[-], and 4,012 were cN[+] and pN[+]. The proportion of patients with any metastatic disease (brain metastases) were as follows: SLNB[+]: 1.4% (0.3%); SLNB[-] 0.3% (<0.1%); cN[+] and pN[+] 11.6% (1.6%). On multivariable regression, Breslow depth > 4, ulceration, and lymphovascular invasion were associated with greater risk of metastatic disease. A supervised decision tree for SLNB[+] and SLNB[-] patients found the only groups with >2% risk of metastases were T4 tumors or T2/T3 tumors with ulceration and LVI. Most groups had a negligible risk (<0.1%) of brain metastases. This is the first large analysis to guide the use of imaging for cutaneous melanoma. Among clinically node negative patients, metastatic disease is uncommon and brain metastases are exceedingly rare. Further investigation could promote a tailored approach to metastatic workups guided by individual risk factors.

Off-label use of fam-trastuzumab deruxtecan-nxki with early activity in a cohort of patients with desmoplastic small round cell tumor.

11584 Background: Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive sarcoma occurring predominantly in pediatric, adolescent and young adult biologic males, and is molecularly characterized by the pathognomonic EWSR1-WT1 fusion. Despite aggressive multi-modality therapy outcomes for those with DSRCT remain poor, and more effective therapies are urgently required. Prior pre-clinical data and transcriptomic analyses of DSRCT patients has suggested the relevance of the ERBB2 pathway in this disease, prompting the off-label use of fam-trastuzumab deruxtecan-nxki (T-DXd) in the treatment of patients of DSRCT patient with relapsed and refractory disease. Methods: Patients with relapsed/refractory DSRCT received T-DXd 5.4 mg/kg intravenously in 21-day cycles. Whole body PET and CT of the chest, abdomen and pelvis were used for monitoring. Response was correlated with HER2 immunohistochemistry (IHC) status and transcriptomic analysis by RNA sequencing (RNAseq) when available. Results: Seven patients received the agent, and at the time of submission 3 patients had at least one follow up imaging test after receiving between 6 and 9 cycles of T-DXd. Treatment was overall well tolerated with the only grade 3 toxicity of transaminitis (in patients with known liver metastases), which self-resolved. All other toxicities including constipation, nausea, and fatigue were grade 2 or less. All 3 patients have experienced clinical benefit including one patient with a RECIST 1.1 partial response and two patients with stable disease. Additionally, favorable responses were noted by PET imaging. Four additional patients with relapsed/refractory DSRCT have initiated off-label treatment with T-DXd and are pending imaging responses. 7/7 and 4/7 patients have available IHC and ERBB2 RNA expression data available respectively. All ERBB2 RNA expression data is elevated when compared with the median across all evaluated pediatric tumors in our institutional series. Conclusions: The use of anti-HER2 therapy in a limited and unselected group of heavily pre-treated DSRCT patients is demonstrating an early signal of activity with minimal toxicity and suggests that formal assessment as monotherapy or in other relevant combinations in clinical trials is warranted. Further correlation with IHC and RNAseq expression data may help optimize correlatives and/or generate biomarkers for future clinical trials.

AL–AMYLOIDOSIS RELATED ADVANCED HEART FAILURE DIAGNOSED THROUGH F–18–FLUTEMETANOL PET SCAN

Abstract Background Systemic amyloidosis (SA) is a group of rare diseases in which abnormal misfolded proteins, amyloid fibrils, accumulate in tissue. The gold standard for diagnosis is tissue biopsy of the affected organ, but it is invasive and needs specific proteomic or immunohistochemistry analyses to characterize the involved protein. We report a case of a complex diagnosis of SA in an advanced heart failure (HF) patient. Methods and Results A 68–year–old woman with history of recurrent uveitis started to complain dyspnea in 2022, after Covid19. Since her symptoms worsened, in June 2023 she was diagnosed in another center with restrictive cardiomyopathy with preserved left ventricular (LV) ejection fraction. She underwent coronary angiography (unremarkable), cardiac MRI (aspecific fibrosis), and a FDG–PET scan which showed non–homogeneous LV fixation. The patient was treated with steroids for the suspicion of an immunologic–inflammatory disease, without benefit. Fourteen months after the initial presentation, she was admitted to our centre for advanced inotrope–dependent HF. She had mildly increased LV hypertrophy and severe systolic dysfunction with restrictive physiology and, notably, peri–orbital subcutaneous hemorrhages (Figure 1). Hematological screening for amyloidosis showed elevated serum free lambda light chains. Repeated cardiac MRI scan was consistent with infiltrative disease. A total–body PET scan with dual tracer was performed. The control session with F–18–FDG showed mild aspecific cardiac uptake in the basal septum and lateral wall (Figure 2), while off–label use of F–18–Flutemetanol, an Alzheimer‘s disease approved experimental tracer that binds to amyloid fibrils beta sheets with very high sensitivity and specificity, showed intense cardiac, hepatic, pulmonary and muscular uptake, with wash–out–timing diagnostic for AL–SA (Figure 3). Periumbilical fat biopsy confirmed the clinical suspicion of SA. Hematological investigations led to the diagnosis of stage I–A lambda micromolecular multiple myeloma, with systemic amyloidosis and a IIIb cardiac prognostic score. Conclusions Endomyocardial biopsy is an invasive procedure and periumbilical fat biopsy discriminates the amyloid protein type only by proteomic analysis, which is available in very few Italian centres. The off–label use of Alzheimers’ PET tracers could reduce the delay of cardiac AL–SA diagnosis, allowing early disease identification and prompting timely hematological therapy.

Comparison of quantitative whole body PET parameters on [68Ga]Ga-PSMA-11 PET/CT using ordered Subset Expectation Maximization (OSEM) vs. bayesian penalized likelihood (BPL) reconstruction algorithms in men with metastatic castration-resistant prostate cancer

BackgroundPSMA PET/CT is a predictive and prognostic biomarker for determining response to [177Lu]Lu-PSMA-617 in patients with metastatic castration resistant prostate cancer (mCRPC). Thresholds defined to date may not be generalizable to newer image reconstruction algorithms. Bayesian penalized likelihood (BPL) reconstruction algorithm is a novel reconstruction algorithm that may improve contrast whilst preventing introduction of image noise. The aim of this study is to compare the quantitative parameters obtained using BPL and the Ordered Subset Expectation Maximization (OSEM) reconstruction algorithms.MethodsFifty consecutive patients with mCRPC who underwent [68Ga]Ga-PSMA-11 PET/CT using OSEM reconstruction to assess suitability for [177Lu]Lu-PSMA-617 therapy were selected. BPL algorithm was then used retrospectively to reconstruct the same PET raw data. Quantitative and volumetric measurements such as tumour standardised uptake value (SUV)max, SUVmean and Molecular Tumour Volume (MTV-PSMA) were calculated on both reconstruction methods. Results were compared (Bland-Altman, Pearson correlation coefficient) including subgroups with low and high-volume disease burdens (MTV-PSMA cut-off 40 mL).ResultsThe SUVmax and SUVmean were higher, and MTV-PSMA was lower in the BPL reconstructed images compared to the OSEM group, with a mean difference of 8.4 (17.5%), 0.7 (8.2%) and − 21.5 mL (-3.4%), respectively. There was a strong correlation between the calculated SUVmax, SUVmean, and MTV-PSMA values in the OSEM and BPL reconstructed images (Pearson r values of 0.98, 0.99, and 1.0, respectively). No patients were reclassified from low to high volume disease or vice versa when switching from OSEM to BPL reconstruction.Conclusions[68Ga]Ga-PSMA-11 PET/CT quantitative and volumetric parameters produced by BPL and OSEM reconstruction methods are strongly correlated. Differences are proportional and small for SUVmean, which is used as a predictive biomarker. Our study suggests that both reconstruction methods are acceptable without clinical impact on quantitative or volumetric findings. For longitudinal comparison, committing to the same reconstruction method would be preferred to ensure consistency.

Sequential deep learning image enhancement models improve diagnostic confidence, lesion detectability, and image reconstruction time in PET

BackgroundInvestigate the potential benefits of sequential deployment of two deep learning (DL) algorithms namely DL-Enhancement (DLE) and DL-based time-of-flight (ToF) (DLT). DLE aims to enhance the rapidly reconstructed ordered-subset-expectation-maximisation algorithm (OSEM) images towards block-sequential-regularised-expectation-maximisation (BSREM) images, whereas DLT aims to improve the quality of BSREM images reconstructed without ToF. As the algorithms differ in their purpose, sequential application may allow benefits from each to be combined. 20 FDG PET-CT scans were performed on a Discovery 710 (D710) and 20 on Discovery MI (DMI; both GE HealthCare). PET data was reconstructed using five combinations of algorithms:1. ToF-BSREM, 2. ToF-OSEM + DLE, 3. OSEM + DLE + DLT, 4. ToF-OSEM + DLE + DLT, 5. ToF-BSREM + DLT. To assess image noise, 30 mm-diameter spherical VOIs were drawn in both lung and liver to measure standard deviation of voxels within the volume. In a blind clinical reading, two experienced readers rated the images on a five-point Likert scale based on lesion detectability, diagnostic confidence, and image quality.ResultsApplying DLE + DLT reduced noise whilst improving lesion detectability, diagnostic confidence, and image reconstruction time. ToF-OSEM + DLE + DLT reconstructions demonstrated an increase in lesion SUVmax of 28 ± 14% (average ± standard deviation) and 11 ± 5% for data acquired on the D710 and DMI, respectively. The same reconstruction scored highest in clinical readings for both lesion detectability and diagnostic confidence for D710.ConclusionsThe combination of DLE and DLT increased diagnostic confidence and lesion detectability compared to ToF-BSREM images. As DLE + DLT used input OSEM images, and because DL inferencing was fast, there was a significant decrease in overall reconstruction time. This could have applications to total body PET.

FAPI PET/CT provides higher uptake and better target to back ground in recurrent and metastatic tumors of patients with Iodine refractory papillary thyroid cancer compared with FDG PET CT.

The role of fibroblast activation protein inhibitor (FAPI) PET CT scan is not well documented in papillary thyroid cancer (PTC) patients. Patients with radioiodine refractory PTC and high thyroglobulin levels need PET/CT scan which is generally done by 18F FDG. In the current study, the diagnostic performance of 68Ga FAPI and FDG PET/CT scans were compared head to head in patients with radioiodine refractory PTC. Fourteen patients with negative whole body Iodine scans and high thyroglobulin levels underwent whole body PET scans with, respectively, 120-310 and 145-370 MBq 68Ga FAPI-46 and 18F FDG. SUVmax of the back ground in the blood pool and liver and the hottest, largest and average neck, mediastinum, lung and bone lesions were calculated and compared. Ten patients had at least one active (SUVmax>blood pool) lesion similarly in two scans. The liver and blood pool SUVmax values were 1.25(0.2) and 1.7(0.2) in FAPI and 2.65(0.2) and 2.0(0.2) in FDG PET images, respectively. The difference was significant (p=0.001). Standard SUV of the hottest lesion to liver was above 3 in all FAPI scans but in half of FDG scans. Target lesion number and intensity were similar between two PET studies but in a patient out of 5 pulmonary metastatic patients, pulmonary nodules were negative (SUVmax=0.9) in FDG while positive (SUVmax= 3.8) in FAPI images (i.e. 20% patient upstaged). FAPI accumulates in the recurrent and metastatic lesions of patients with Iodine refractory PTC at least as well as FDG with particular privileges as lower injected activity and lower back ground.

The radiation dose from whole body hybrid imaging (PET–CT) procedures in Sri Lanka: The initial approach towards establishing national diagnostic reference level

Positron emission tomography-Computed tomography (PET–CT) is a hybrid imaging modality that is increasingly used in the diagnosis and staging of cancer. However, due to its hybrid nature, PET–CT is associated with a high radiation dose, which is a concern for patient safety. The aim of this study is to assess the radiation dose from both components of PET and CT to establish diagnostic reference levels (DRLs) that can be used as a tool for dose optimization. This study presents the results of the initial attempt to establish DRLs for body PET–CT procedures among adults and children in Sri Lanka.Data on the injected activity (MBq) and CT radiation dose, volume CT dose index (CTDIvol) and dose length product (DLP) were collected from three PET–CT centers in Sri Lanka and the institutional diagnostic reference level (IDRL) has been established using the median dose distribution for each center and procedure. The median of the individual IDRLs was presented as the national diagnostic reference level (NDRL). Additionally, the mean, standard deviation, 25th, and 75th percentiles of the pooled dose distribution have been presented with and without weight restrictions for adults, as well as for several age and weight bins for pediatrics.The average injected activity of standard adult patients was 187 ± 37 MBq while for pediatric patients aged 1 to 15 years, it ranged between 105 ± 22 and 139 ± 43 MBq. The average CT dose based on CTDIvol and DLP for a standard adult were 3.81 ± 0.86 mGy and 668 ± 140 mGy.cm. The average CTDIvol and DLP ranged between 2.05 ± 0.76–3.65 ± 1.59 and 195 ± 50–411 ± 188 for pediatric patients. The NDRL based on injected activity for adults and pediatric was 198.3 203.3 MBq and 127.7 MBq. The levels of injected activity for adult patients were found to be lower than those published internationally. However, procedures involving both PET and CT in pediatric patients require dose optimization.The present study proposed IDRL and NDRL values for body PET–CT procedures in Sri Lanka. The findings indicate that these values can serve as an effective guide for achieving further optimization in dose, particularly in procedures involving both PET and CT in pediatric patients.

SAT240 Recurrent Hypercalcemia Due To 1,25 Dihydroxy Vitamin D Elevation Of Unclear Etiology

Abstract Disclosure: A. Javvaji: None. C. Anastasopoulou: None. Introduction: Recurrent Hypercalcemia is common with primary hyperparathyroidism and malignancy accounting for 90% of cases. Extra renal activation of 1α-hydroxylase with subsequent elevation of 1,25 dihydroxy vitamin D is a relatively uncommon cause of hypercalcemia. Herein, we report an unusual case of recurrent hypercalcemia due to elevated 1,25 dihydroxy vitamin D of unclear etiology, resistant to therapy with denosumab or bisphosphonate that responded to glucocorticoid therapy. Case Presentation: A 68 year old female was admitted to the hospital for worsening calcium with symptoms of polyuria and increased thirst. Review of systems and physical examination were otherwise unremarkable. Initial work-up demonstrated calcium level of 11.7mg/dL (8.7-10.3), creatinine 2.58 mg/dL (0.57-1), PTH 8pg/mL (15-65), Kappa/Lamba ratio 1.82 (0.26-1.6), PTHrP 11pg/mL (11-20), 25 (OH) Vitamin D 14ng/mL (30-100), 24,25 Dihydroxy Vitamin D ratio 25.81 (&amp;lt;25). Bone marrow biopsy, kidney biopsy, and myeloma work up were all unremarkable. Imaging studies including whole body CT and PET CT were also unremarkable. In the acute phase patient was treated with zoledronic acid and later denosumab with only temporary decrease in calcium levels. Ultimately, she responded well to prednisone therapy. Further work-up for finding the underlying cause of elevated 1,25 dihydroxy vitamin D remains ongoing. Discussion: Elevated 1,25 dihydroxy vitamin D level in granulomatous, neoplastic, and certain unusual diseases is well recognized as a cause of hypercalcemia. These levels may be exacerbated by increased intake of calcitriol, or by extra-renal production in granulomatous and lymphoproliferative diseases. Other rare causes of elevated 1,25 dihydroxy vitamin D include granulomatosis with polyangiitis, cat scratch fever, talc granulomatosis, Crohn’s disease, silicone granulomatosis. Patients with all these diseases respond well to steroids and that was another sign that further work-up to find the source of the elevated 1,25 dihydroxy vitamin D in our case is essential. Conclusion: In patients with recurrent hypercalcemia and elevated 1,25 dihydroxy vitamin D levels, a complete work-up for underlying malignancy, granulomatous or other unusual diseases is indicated. Glucocorticoid therapy is the most effective way to control the hypercalcemia related to increased 1,25 dihydroxy vitamin D even in the long-term phase, especially until the main cause of the problem is identified and treated appropriately. Presentation: Saturday, June 17, 2023

SAT323 Management Of Severe Cushing’s Syndrome Due To Cortisol Secreting Adrenal Tumor In A Critically Ill Patient

Abstract Disclosure: H. Obeid: None. E.D. Buras: None. T. Else: None. Introduction: Severe Cushing’s syndrome is associated with multiple life threatening complications. Clinical Case: A 69 year-old man with Cushing’s syndrome was admitted to the hospital with septic shock due to bacteremia with necrotic left lower extremity infection. He required above knee amputation. His hospital course was complicated with invasive pulmonary Aspergillosis and ventilator associated pneumonia. He developed acute kidney injury that required dialysis, altered mental status, deep venous thrombosis bilateral pulmonary embolisms, bleeding duodenal ulcer and retroperitoneal hematoma. Prior to admission: Random cortisol was 31.7 mcg/dL (Normal: 4.8-19.5 mcg/dL), AM Cortisol following 1 mg oral dexamethasone was 47 mcg/dL (Normal: &amp;lt;1.8 mcg/dL), DHEA-s was 210 mcg/dL (normal: 33.6-249 mcg/dL) and 24 hour urine free cortisol was 622 mcg/day (Normal: &amp;lt;60 mcg/day). ACTH was undetectable. An FDG-PET scan showed a 6.5 centimeters hypermetabolic left adrenal mass with internal coarse calcifications but no evidence of metastasis. Etomidate drip, Metyrapone and Osilodrostat were tried to lower excess cortisol production. During admission while on Osilodrostat: Cortisol level: 20 mcg/dL (normal: 8-19 mcg/dL). Deoxycorticosterone: 53 ng/dL (Normal: 2-19 ng/dL). 11-Desoxycortisol: 580 ng/dL (Normal: 12-158 ng/dL). 17-alpha-hydroxyprogesterone: 45 ng/dL (Normal: 27-199 ng/dL). Surgery was considered, but adrenalectomy was deemed high risk and not pursued. Therefore, the patient underwent computed tomography (CT) cryoablation of the left adrenal gland. Labs following cryoablation: Cortisol: 7.7 mcg/dL. Deoxycorticosterone: 10 ng/dL. 11-Desoxycortisol: 34 ng/dL. 17-alpha-hydroxyprogesterone: 25 ng/dL. The procedure was complicated by T11/T12 intercostal artery injury leading to hemothorax. He was continued on physiologic doses of hydrocortisone. On follow up 4 weeks following discharge, he had complete resolution of hypercortisolism symptoms. A repeat whole body PET scan showed persistent FDG-avid neoplasm in left adrenal area, as well as metastasis in the liver and the duodenum. Conclusion: It is critical to control hypercortisolism in patients with Cushing’s syndrome. Several medications can be used. Surgical adrenalectomy remains the gold standard for treatment. CT-guided cryoablation of the adrenal tumor is a reasonable alternative when patient is not a surgical candidate. However, it is not a completely benign procedure as it can be associated with complications. Our treatment approach improved short term outcome for our patient, but did not provide long term benefit since he developed metastasis. Presentation: Saturday, June 17, 2023

Abstracts of the Total Body PET 2022 conference

Abstracts of the Total Body PET 2022 conference

Analisis Laporan Keuangan Segmentasi Pada Perusahaan PT Kino Indonesia Tbk

Companies going public usually make disclosures on the reporting of segmentation of their company's operations. Segmentation reporting aims for stakeholders to see the company's financial statements behind the consolidated amount for each component that makes up the entity. In PT Kino Indonesia Tbk there are five segments in it, including body care, beverages, food, pharmaceuticals and pet food. This study aims to analyze the segment in accordance with the ten percent test of revenue, profit and loss and assets in the 2018-2022 Annual Report. In analyzing this segment report in accordance with PSAK number 5. The method carried out in this study is a qualitative descriptive method. The results of research at PT Kino Indonesia Tbk, it can be concluded that from these three tests, the average segment that can be reported is the segment (body care, beverages, and food) because it passed the ten percent test. While in the segment (pharmaceutical and pet food) All three tests could not be reported because they did not pass the 10% test. Thus, PT Kino Indonesia Tbk and subsidiaries from 2018 to 2022 are still less effective in implementing PSAK 5.

High time-resolution MRPC detector for TOF-PET

The traditional TOF-PET (Positron emission tomography) mainly uses the structure of a scintillator detector connected to a photomultiplier tube. The structure has the disadvantages that time resolution is not good enough (about 300 ps FWHM) for improving the signal-to-noise ratio of the acquisition system, which is not conducive to the detection of microtumors in the clinic and reduction in imaging time. The thickness of the scintillator is large (greater than 3 cm). Traditional PET has low geometric efficiency and sensitivity. It requires a long time to complete a full-body scan. However, the MRPC can be made into a 2.4-meter-long whole body PET. The high cost of traditional TOF-PET limits its widespread use in medical and other fields. The excellent time resolution of MRPC makes MRPC TOF-PET a good application prospect. This paper shows the time resolution of two 32-gap MRPCs with 128μm gap thickness on cosmic rays and 0.511 MeV photons. By using the fast front-end amplifier and waveform acquisition system, the time resolution for cosmic rays is 27 ps and the rms time accuracy per 0.511 MeV photon is 72 ps. The time resolution in terms of FWHM of the time difference between photon pairs is 239 ps FWHM. The reason why MRPC detectors have different time resolutions for cosmic rays and 0.511 MeV photons is related to the different ways different particles act and the thickness of the detector. We propose to use a Cerenkov radiator to convert gamma into ultraviolet photons and use a composite photocathode to detect, improving the detection efficiency to 6.4% for RPC.

18F-MFBG PET imaging in patients with neuroblastoma: Lesion targeting and comparison with MIBG.

10046 Background: 123I-MIBG gamma camera imaging (MIBG) is routinely used for the imaging of neuroblastoma. Limitations include need for two-day imaging schedule and lack of quantitative uptake measurements. Phase I study showed that 18 F-MFBG (MFBG), a positron-emitting analog of MIBG, is safe and feasible (PMID:28705916). In the follow-up phase II trial (NCT02348749) we evaluated MFBG PET imaging, comparing neuroblastoma lesion between the two modalities. Methods: Patients with known neuroblastoma underwent whole- body PET CT or PET-MR imaging one hour post-injection with 8mCi/1.7m2 of MFBG. All patients had concurrent MIBG scan with planar and SPECT-CT imaging without intervening therapy. MFBG and MIBG images were independently analyzed for lesion targeting; lesion number, site and uptake was noted for each patient and compared. Discordant lesions were further investigated with correlative imaging and/or clinical follow up. MFBG score was generated, similar to the modified Curie score for MIBG, for each patient. Results: 25 patients (median age 8 y) underwent MFBG scans at a median of 2 (range 0-24) days after MIBG scans; in one patient MFBG scan was performed 1 day before MIBG scan. No MFBG-related adverse events were noted. 24 patients had both MIBG and MFBG positive scans while 1 patient had both MIBG and MFBG negative scans. A total of 367 lesions were visualized on MFBG as against 217 on MIBG. There were no MIBG-positive that were negative on MFBG. A median number of 11 (range 0-57) lesions per patient were detected on MFBG scan. Uptake was noted in osteomedullary only, (n=13), soft tissue only (n=1) and both soft tissue and osseous lesions (n=10). MFBG detected a median of 6 (range 1-24) additional lesions in 19 patients. In 16/19 patients where follow up was available, the discordance was related to true positive disease, including at least 116 sites. Respective median curie scores were 3 (range:0-22) and 9 (range:0-24) with MIBG and MFBG respectively. Conclusions: MFBG scan detected disease in all patients with MIBG positive disease. MFBG detected similar or more lesions compared to MIBG in patients with neuroblastoma, with overall increased scores. Further analysis to evaluate impact on patient management is underway. Clinical trial information: NCT02348749 .

P74 NIGHT SWEATS AND AN UNUSUAL RIGHT ATRIAL MASS

Abstract Background Primary cardiac tumors are infrequently, usually benign, and diagnosed incidentally. Among primary cardiac tumors, cardiac hemangiomas are exceptionally rare with only a 1–2% incidence. In most cases, histological diagnosis is made after surgical removal or at autopsy. Case presentation: A 36–year–old male patient is suffering from several months of bothering night sweats. He has no previous medical history and is not taking medication. After performing various exams, including an electrocardiogram and chest rx–ray that were unremarkable, the patient performed a chest TC scan that shows a large mass at right atrial level (Figure 1). Surprisingly, at transthoracic echocardiography the mass was not visible and moreover the exam was normal. To better visualize the mass, a transesophageal echocardiography was performed, showing a inhomogeneous, round–shape, intracavitary mass of 70x65 mm in size. The mass appear to be fixed, expansive, with no embolic–features and seem to be initially–obstructing the upper–cava blood flow (Figure 2), even the patient was hemodynamically stable. A diagnosis of lymphoma was initially suspected and an Total–body PET–TC was performed, showing that the heart mass was metabolically inactive and an intestinal metabolic active mass. Intestine mass biopsy, made by colonscopy, showed a non–malignous villous adenoma. Before undergoing heart surgery, to understand the nature of the mass, we performed a intracavitary ecocardiography (ICE)–guided percutaneous biopsy. Histologically, the heart tumor was composed of cavernous channels embedded in a loose fibrous stroma, compatible with Cavernous hemangioma. At heart surgery, the mass was localized inside the right atrium, at upper–front level, adhered to a small part of atrial myocardium, and was removed without complications. The right atrium was rebuilt with artificial patch. (Figure 3). Conclusions Cavernous cardiac Hemangioma is a rare tumor that may have an atypical clinical presentation. To our knowledge, this is the first case of cardiac hemangioma diagnosed by ICE–guided endomyocardial biopsy.

P325 CARDIAC SARCOIDOSIS PRESENTING WITH ATRIOVENTRICULAR BLOCK AND SUBSEQUENT CARDIAC ARREST: A CASE REPORT

Abstract A 53–year–old male patient with no significant past medical history and no familiar history for cardiac diseases presented to the emergency department for asymptomatic bradycardia. The ECG showed complete atrioventricular block in the absence of pathological findings on the echocardiogram and no coronary lesions were found on coronary angiography. The patient underwent pacemaker (PM) implantation. A few months later the patient suffered from cardiac arrest in sustained ventricular tachycardia, effectively treated with DC shock. The echocardiogram showed mild right ventricular dilation and dysfunction with regional wall motion abnormalities, especially in the subtricuspid site. Cardiac magnetic resonance imaging (MRI) showed focal areas of delayed enhancement with a non–ischaemic pattern and distribution with a hook sign, highly suggestive of cardiac sarcoidosis. FDG PET showed cardiac, hepatic, splenic, and lymph nodal uptake. In the suspicion of systemic sarcoidosis, an hepatic biopsy was performed, being the liver the most accessible site. The histological examination showed the presence of non–caseating granulomas. Therefore, a diagnosis of Systemic Sarcoidosis (SS) with Cardiac involvement was made and the PM was upgraded to CRT–D in secondary prevention. The patient was discharged with cortisone therapy. Three months after discharge, a new total body PET–CT scan was performed and showed, in comparison to the previous one, the absence of areas of significant hypermetabolism in the cardiac, hepatic and bone fields. Cardiac sarcoidosis (CS) is a rare inflammatory granulomatous myocardial disease of unknown etiology that should be suspected in young patients with atrioventricular conduction disturbances and complex ventricular arrhythmias. The diagnostic approach is challenging: imaging techniques (MRI, PET) can be suggestive of CS but biopsy with histological demonstration of the non–caseous granuloma is mandatory. Endomyocardial biopsy (which has suboptimal sensitivity due to focal lesion) could be avoided if there is a more accessible and less invasive extracardiac site for biopsy. Early diagnosis relies on multidisciplinary collaboration and is essential for staging and long–term management of the disease and prevention of sudden cardiac death. Cortisone therapy remains the mainstay of treatment.