Nuclear Imaging Modalities Research Articles

Somatostatin Receptor Type 2 as a Potential Marker of Local Myocardial Inflammation in Myocardial Infarction: Morphologic Data on Distribution in Infarcted and Normal Human Myocardium.

Nuclear imaging modalities can detect somatostatin receptor type 2 (SSTR2) in vivo as a potential marker of local post-MI inflammation. SSTR2+ macrophages are thought to be the main substrate for SSTR-targeted radioimaging. However, the distribution of SSTR2+ cells in the MI patients' myocardium is unknown. Using immunohistochemistry, we investigated the distribution of SSTR2+ cells in the myocardium of patients who died during the MI inflammatory phase (n = 7) compared to the control group of individuals with fatal trauma (n = 3). Inflammatory cellular landscapes evolve in a wave front-like pattern, so we divided the myocardium into histological zones: the infarct core (IC), the border zone (BZ), the remote zone (RZ), and the peri-scar zone (PSZ). The number of SSTR2+ neutrophils (NPs), SSTR2+ monocytes/macrophages (Mos/MPs), and SSTR2+ vessels were counted. In the myocardium of the control group, SSTR2+ NPs and SSTR2+ Mos/MPs were occasional, SSTR2+ vessels were absent. In the RZ, the picture was similar to the control group, but there was a lower number of SSTR2+ Mos/MPs in the RZ. In the PSZ, SSTR2+ vessel numbers were highest in the myocardium. In the IC, the median number of SSTR2+ NPs was 200 times higher compared to the RZ or control group myocardium, which may explain the selective uptake of SSTR-targeted radiotracers in the MI area during the inflammatory phase of MI.

Evaluation of heterotopic ossification maturity using SPECT/CT and PET/CT in preclinical model

BackgroundHeterotopic ossification (HO) is the formation of bone within soft tissue where bone normally does not exist. In general, it is characterized by highly active tissue with high bone turnover and rapid bone formation. It is of an utmost importance to precisely identify and accurately diagnose the maturity of HO as early surgical intervention may result in its recurrence. The objective of this work is the experimental evaluation of HO maturity stage using advanced noninvasive nuclear medicine techniques. The use of PET radiopharmaceuticals may result in a more specific diagnosis between the phases due to their higher sensitivity and better resolution compared to bone scan. Method8-week-old Balb/c male mice underwent dual injury procedure, tenotomy and concurrent burn injury on the left side, to induce HO. The progression of HO was monitored by SPECT/CT and PET/CT weekly imaging with 99mTc-MDP, [18F]NaF and [18F]FDG for up to 16 weeks. ResultsThere was a statistically significant increase of [18F]FDG uptake from week 1 to 2 and from week 2 to 6 with p values of 0.01 and 0.005; respectively, while there was a statistically significant decrease from week 7 to 14 with a p value of 0.008. There was a statistically significant increase of [18F]NaF uptake from week 2 to 5 and statistically significant decrease between weeks 7 and 14 with p values of 0.016 and 0.003; respectively. As for 99mTc-MDP, the increase in the uptake from week 1 to 2 and from week 2 to 5 were not statistically significant with p values of 0.15 and 0.19; respectively. The decrease of uptake between week 7 and 14 was not statistically significant with a p value of 0.08. ConclusionBased on these findings, the use of noninvasive nuclear imaging modalities may assist in distinguishing between the immature and mature phases. The uptake of mainly [18F]FDG may indicate the early inflammatory phase, while the uptake of both [18F]FGD and [18F]NaF may suggest the immature phase, and an uptake of mainly [18F]NaF may indicate the maturity phase of HO.

Match Point: Nuclear Medicine Imaging for Recurrent Thyroid Cancer in TENIS Syndrome-Systematic Review and Meta-Analysis.

Background/Objectives: Disease recurrence and resistance to radioiodine (RAI) therapy are major challenges in the management of differentiated thyroid cancer (DTC). In particular, the TENIS (Thyroglobulin Elevated Negative Iodine Scintigraphy) syndrome, characterised by elevated thyroglobulin (Tg) serum levels in addition to a negative radioiodine whole body scan (WBS), complicates disease monitoring and treatment decisions. Conventional imaging techniques often fail to detect disease in WBS-negative patients with rising Tg levels, leading to limitations in therapeutic intervention. This systematic review and meta-analysis aims to evaluate the diagnostic accuracy of nuclear imaging modalities in detecting disease recurrence in patients with the TENIS syndrome and to provide insights to guide therapeutic approaches in this complex clinical scenario. Methods: A comprehensive search of PubMed/MEDLINE and EMBASE databases up to March 2024 was performed according to PRISMA guidelines. Eligible studies were selected, and quality assessment was performed with the QUADAS-2 tool. For each study, relevant data were extracted and synthesised. A meta-analysis of the diagnostic accuracy of [18F]FDG PET/CT was performed, and patient-based pooled sensitivity and specificity were calculated using a random-effects model. Statistical heterogeneity between studies was assessed using the I2 statistic. Results: Of the 538 studies initially identified, 22 were included in the systematic review, of which 18 were eligible for meta-analysis. The eligible studies, mainly focused on [18F]FDG PET/CT, showed variable sensitivity and specificity for the detection of RAI-refractory thyroid cancer lesions. For [18F]FDG PET/CT, pooled estimates displayed a sensitivity of 0.87 (95% CI: 0.82-0.90) and a specificity of 0.76 (95% CI: 0.61-0.86), with moderate heterogeneity between studies. Conclusions: [18F]FDG PET/CT remains central in the detection of disease recurrence in patients with the TENIS syndrome. The emergence of novel radiopharmaceuticals with specific molecular targets is a promising way to overcome the limitations of [18F]FDG in these patients and to open new theranostics perspectives. This review highlights the great potential of nuclear medicine in guiding therapeutic strategies for RAI-refractory thyroid cancer.

Nuclear Imaging Modalities in the Diagnosis and Management of Thyroid Cancer.

In this review we have brought forward various nuclear imaging modalities used in the diagnosis, staging, and management of thyroid cancer. Thyroid cancer is the most common endocrine malignancy, accounting for approximately 3% of all new cancer diagnoses. Nuclear imaging plays an important role in the evaluation of thyroid cancer, and the use of radioiodine imaging, FDG imaging, and somatostatin receptor imaging are all valuable tools in the management of this disease. Radioiodine imaging involves the use of Iodine-123 [I-123] or Iodine-131 [I-131] to evaluate thyroid function and detect thyroid cancer. I-123 is a gamma-emitting isotope that is used in thyroid imaging to evaluate thyroid function and detect thyroid nodules. I-131 is a beta-emitting isotope that is used for the treatment of thyroid cancer. Radioiodine imaging is used to detect the presence of thyroid nodules and evaluate thyroid function. FDG imaging is a PET imaging modality that is used to evaluate the metabolic activity of thyroid cancer cells. FDG is a glucose analogue that is taken up by cells that are metabolically active, such as cancer cells. FDG PET/CT can detect primary thyroid cancer and metastatic disease, including lymph nodes and distant metastases. FDG PET/CT is also used to monitor treatment response and detect the recurrence of thyroid cancer. Somatostatin receptor imaging involves the use of radiolabeled somatostatin analogues to detect neuroendocrine tumors, including thyroid cancer. Radiolabeled somatostatin analogues, such as Indium-111 octreotide or Gallium-68 DOTATATE, are administered to the patient, and a gamma camera is used to detect areas of uptake. Somatostatin receptor imaging is highly sensitive and specific for the detection of metastatic thyroid cancer. A comprehensive search of relevant literature was done using online databases of PubMed, Embase, and Cochrane Library using the keywords "thyroid cancer," "nuclear imaging," "radioiodine imaging," "FDG PET/CT," and "somatostatin receptor imaging" to identify relevant studies to be included in this review. Nuclear imaging plays an important role in the diagnosis, staging, and management of thyroid cancer. The use of radioiodine imaging, thyroglobulin imaging, FDG imaging, and somatostatin receptor imaging are all valuable tools in the evaluation of thyroid cancer. With further research and development, nuclear imaging techniques have the potential to improve the diagnosis and management of thyroid cancer and other endocrine malignancies.

Nuclear Imaging in Orthopaedic Practice: A Critical Analysis Review.

» Nuclear imaging techniques, including bone scintigraphy, labeled leukocyte scintigraphy, positron emission tomography (PET), and single-photon emission computed tomography (SPECT) combined with computed tomography (CT), have wide applications in orthopaedics for evaluating trauma, painful total joint arthroplasty, musculoskeletal infection, and orthopaedic oncology.» Three-phase bone scintigraphy is a first-line, highly sensitive nuclear medicine study for evaluating orthopaedic pathology when initial studies are inconclusive. However, its specificity is limited, and findings may be falsely positive for up to 2 years after total joint arthroplasty because of physiologic bone remodeling.» Labeled leukocyte scintigraphy or gallium scintigraphy can improve diagnostic accuracy in patients with a positive bone scan and suspected musculoskeletal or periprosthetic joint infection.» 18-Fluorodeoxyglucose PET/CT demonstrates high sensitivity and specificity for diagnosing bone neoplasms, infections, and metabolic disorders. Emerging PET/magnetic resonance imaging technology offers reduced radiation exposure and greater soft-tissue detail but presents technical and cost challenges.» SPECT/CT provides valuable functional and anatomic detail for characterizing the extent and location of bone pathology, serving as an important adjunct to other imaging modalities.» Ultimately, the choice of nuclear imaging modality should consider the specific clinical context, diagnostic accuracy, impact on management, and cost-effectiveness on a case-by-case basis.

C-H Labeling with [18F]Fluoride: An Emerging Methodology in Radiochemistry.

Fluorine-18 is the most routinely employed radioisotope for positron emission tomography, a dynamic nuclear imaging modality. The radiolabeling of C-H bonds is an attractive method for installing fluorine-18 into organic molecules since it can preclude the cumbersome prefunctionalization of requisite precursors. Although electrophilic "F+" reagents (e.g., [18F]F2) are effective for C-H radiolabeling, state-of-the-art methodologies predominantly leverage high molar activity nucleophilic [18F]fluoride sources (e.g., [18F]KF) with substantial (pre)clinical advantages. Reflecting this, multiple nucleophilic C-H radiolabeling techniques of high utility have been disclosed over the past decade. However, the adoption of (pre)clinical C-H radiolabeling has been slow, and PET imaging agents are still routinely prepared via methods that, despite a high level of practicality, are limited in scope (e.g., SNAr, SN2 radiofluorinations). By addressing the drawbacks inherent to these strategies, C-H radiofluorination and radiofluoroalkylation carry the potential to complement and supersede state-of-the-art labeling methods, facilitating the expedited production of PET agents used in disease staging and drug development. In this Outlook, we showcase recent C-H labeling developments with fluorine-18 and discuss the merits, potential, and barriers to adoption in (pre)clinical settings. In addition, we highlight trends, challenges, and directions in this emerging field of study.

Applications of SPECT and PET Imaging for the Physiological Evaluation of Lower Extremity Peripheral Artery Disease.

Peripheral artery disease (PAD) is classified as the narrowing or complete occlusion of the lower extremity arteries due to atherosclerosis. The risk of developing PAD increases with increased age and risk factors such as smoking, diabetes, hypertension, and hypercholesterolemia. Current treatment for PAD involves lifestyle and symptom management, statin and antiplatelet therapy, and/or surgical interventions to improve quality of life with varying efficacy. PAD affects approximately 5 to 6 percent of the global population, with this global burden continuing to increase. Despite the increase in disease prevalence, no gold standard functional diagnostic tool has been established for enabling early detection of the disease, appropriate medical management, and prediction of adverse outcomes for PAD patients. The visualization and quantification of the physiological consequences of PAD are possible by way of nuclear imaging: specifically, via scintigraphy, single-photon emission computed tomography (SPECT), and positron emission tomography (PET) imaging. These non-invasive modalities, when combined with targeted radionuclides, possess utility for detecting functional perfusion deficits and provide unique insight into muscle tissue- and vascular-level characteristics of PAD patients. This review discusses the past, present, and emerging applications of hybrid nuclear imaging modalities in the evaluation and monitoring of patients with PAD.

Papillary Thyroid Cancer, Small Cell Lung Cancer, and Parathyroid Adenoma Synchronously Visualized on 99m Tc-MIBI SPECT/CT in a Patient With Hyperparathyroidism : Comparison With 18 F-FDG PET/CT.

99m Tc-MIBI scintigraphy is a nuclear medicine imaging modality commonly used for the preoperative localization of parathyroid adenomas in patients with hyperparathyroidism. In addition, 99m Tc-MIBI can also be used for imaging various tumors due to its unique mechanism of intracellular accumulation. Here, we introduced a case of a single 99m Tc-MIBI SPECT/CT simultaneously visualized two different malignant tumors, such as papillary thyroid cancer and small cell lung cancer, along with a parathyroid adenoma in a patient with hyperparathyroidism. The clinical usefulness of 99m Tc-MIBI SPECT/CT was also explored by comparing it with 18 F-FDG PET/CT among the three tumors.

Nuclear medicine imaging for bone metastases assessment: what else besides bone scintigraphy in the era of personalized medicine?

Accurate detection and reliable assessment of therapeutic responses in bone metastases are imperative for guiding treatment decisions, preserving quality of life, and ultimately enhancing overall survival. Nuclear imaging has historically played a pivotal role in this realm, offering a diverse range of radiotracers and imaging modalities. While the conventional bone scan using 99mTc marked bisphosphonates has remained widely utilized, its diagnostic performance is hindered by certain limitations. Positron emission tomography, particularly when coupled with computed tomography, provides improved spatial resolution and diagnostic performance with various pathology-specific radiotracers. This review aims to evaluate the performance of different nuclear imaging modalities in clinical practice for detecting and monitoring the therapeutic responses in bone metastases of diverse origins, addressing their limitations and implications for image interpretation.

Malignant tumor implants after endoscopic thyroidectomy for oncocytic thyroid adenoma: A rare case report

Oncocytic carcinoma of the thyroid, previously referred to as Hurthle cell carcinoma, is a rare and aggressive form of thyroid cancer. In this particular case, a 71-year-old female presented with a palpable neck mass and a history of endoscopic thyroidectomy performed five years prior. Histopathological analysis confirmed the diagnosis of oncocytic carcinoma. In this report, we describe a unique case involving the implantation of a malignant tumor in a postoperative oncocytic thyroid adenoma, which notably exhibited the "flip-flop" phenomenon, as identified through nuclear imaging modalities.

The Role of Multimodality Imaging in Patients with Congenital Heart Disease and Infective Endocarditis.

Infective endocarditis (IE) represents an important medical challenge, particularly in patients with congenital heart diseases (CHD). Its early and accurate diagnosis is crucial for effective management to improve patient outcomes. Multimodality imaging is emerging as a powerful tool in the diagnosis and management of IE in CHD patients, offering a comprehensive and integrated approach that enhances diagnostic accuracy and guides therapeutic strategies. This review illustrates the utilities of each single multimodality imaging, including transthoracic and transoesophageal echocardiography, cardiac computed tomography (CCT), cardiovascular magnetic resonance imaging (CMR), and nuclear imaging modalities, in the diagnosis of IE in CHD patients. These imaging techniques provide crucial information about valvular and intracardiac structures, vegetation size and location, abscess formation, and associated complications, helping clinicians make timely and informed decisions. However, each one does have limitations that influence its applicability.

Evaluation of Pendrin Expression Using Nuclear Imaging Modalities and Immunohistochemistry in Animal Thyroid Cancer Model.

The impaired ability of thyroid cancer (TC) cells to uptake and concentrate iodine represents a major therapeutic challenge in malignant TC management. This has been reported probably due to reduced or loss of expression of pendrin in thyroid tumors. In view of this, we evaluated the pendrin expression in the chemically induced (using N-bis[2-hydroxypropyl] nitrosamine [DHPN]) TC model in Wistar rats. Uptake in the thyroid gland was evaluated by positron emission tomography with computed tomography (PET-CT) and scintigraphy imaging. Further histopathology (HP) and immunohistochemistry (IHC) were performed for confirming malignancy. The altered uptake in the thyroid gland was observed by PET-CT and scintigraphy imaging. Significant pathological changes in the thyroid were observed using 2-deoxy-2-(fluorine-18) fluoro-D-glucose PET-CT, technetium-99m pertechnetate imaging, and reduced iodine-131 uptake (n = 4) in DHPN-induced animals compared to control indicative of thyroid cell proliferation. In treated groups, tissue HP revealed hyperplastic follicular to papillary cell proliferation with variable mitotic activity. The malignant nature of the tissue and variable uptake of the tracer were further reconfirmed by IHC. IHC revealed reduced pendrin expression in malignant thyroid tissue. Hence, nuclear imaging techniques can be of aid in the early identification and evaluation of cellular changes during the early development of tumor models in laboratory animals. In conclusion, our study reveals that pendrin expression plays a vital role in thyroid uptake, and its reduction was observed in TC in a chemically induced TC model.

CD64 as novel molecular imaging marker for the characterization of synovitis in rheumatoid arthritis

BackgroundRheumatoid arthritis (RA) is one of the most prevalent and debilitating joint diseases worldwide. RA is characterized by synovial inflammation (synovitis), which is linked to the development of joint destruction. Magnetic resonance imaging and ultrasonography are widely being used to detect the presence and extent of synovitis. However, these techniques do not reveal the activation status of inflammatory cells such as macrophages that play a crucial role in synovitis and express CD64 (Fc gamma receptor (FcγR)I) which is considered as macrophage activation marker.ObjectivesWe aimed to investigate CD64 expression and its correlation with pro-inflammatory cytokines and pro-damaging factors in human-derived RA synovium. Furthermore, we aimed to set up a molecular imaging modality using a radiolabeled CD64-specific antibody as a novel imaging tracer that could be used to determine the extent and phenotype of synovitis using optical and nuclear imaging.MethodsFirst, we investigated CD64 expression in synovium of early- and late-stage RA patients and studied its correlation with the expression of pro-inflammatory and tissue-damaging factors. Next, we conjugated an anti-CD64 antibody with IRDye 800CW and diethylenetriamine penta-acetic acid (DTPA; used for 111In labeling) and tested its binding on cultured THP1 cells, ex vivo RA synovium explants and its imaging potential in SCID mice implanted with human RA synovium explants obtained from RA patients who underwent total joint replacement.ResultsWe showed that CD64 is expressed in synovium of early and late-stage RA patients and that FCGR1A/CD64 expression is strongly correlated with factors known to be involved in RA progression. Combined, this makes CD64 a useful marker for imaging the extent and phenotype of synovitis. We reported higher binding of the [111In]In-DTPA-IRDye 800CW anti-CD64 antibody to in vitro cultured THP1 monocytes and ex vivo RA synovium compared to isotype control. In human RA synovial explants implanted in SCID mice, the ratio of uptake of the antibody in synovium over blood was significantly higher when injected with anti-CD64 compared to isotype and injecting an excess of unlabeled antibody significantly reduced the antibody-binding associated signal, both indicating specific receptor binding.ConclusionTaken together, we successfully developed an optical and nuclear imaging modality to detect CD64 in human RA synovium in vivo.

The Role of Bone Scintigraphy and Parathyroid Scintigraphy on Multiple Osteolytic Lesions Which Misdiagnosed as Primary Bone Tumor (Giant Cell Tumor)

<p>Brown tumor is a non-neoplastic lesion that resulting from abnormal bone metabolism. It can be manifest in prolonged or untreated hyperparathyroidism. The clinical symptoms, radiological and histopathological examination were similar with giant cell tumor and can be mimicking metastases; or even misdiagnosed with giant cell tumor and mistreated the patient. Biochemical examination of calcium levels and parathyroid hormone should be included in the routine assessment of patients with multiple osteolytic lesions. A multidiscipline approach is needed.Throughout this case report, we would like to report the important role of Nuclear Medicine and Molecular Theranostic imaging modality in 38-year-old male with multiple osteolytic lesions, which was first diagnosed as giant cell tumor and differential diagnosis bone metastases but turnout to be a metabolic bone disease (brown tumor) with parathyroid adenoma as etiology.</p>

Nadir Prostate-specific Antigen as an Independent Predictor of Survival Outcomes: A Post Hoc Analysis of the PROSPER Randomized Clinical Trial.

This post hoc analysis of PROSPER evaluated the relationship between depth of PSA decline and clinical outcomes in enzalutamide-treated men with nonmetastatic castration-resistant prostate cancer. PROSPER was an international, randomized, double-blind, placebo-controlled, phase 3 trial that demonstrated significantly improved metastasis-free survival and overall survival with androgen deprivation therapy plus enzalutamide vs placebo. A total of 905 enzalutamide-treated men were included in this post hoc analysis. Metastasis-free survival (primary endpoint) and overall survival (secondary endpoint) were evaluated for 4 mutually exclusive subgroups defined by PSA decline: <50% (reference); ≥50% to <90%; ≥90%, nadir ≥0.2 ng/mL; and ≥90%, nadir <0.2 ng/mL. Medians and 95% confidence intervals were determined using a 12-month landmark analysis; hazard ratios and P values were based on an unstratified Cox proportional analysis model. In enzalutamide-treated men, PSA declines of <50%, ≥50% to <90%, ≥90% with nadir ≥0.2 ng/mL, and ≥90% with nadir <0.2 ng/mL were associated with median metastasis-free survival in months (95% confidence intervals) of 22.1 (14.8-not reached), 34.2 (29.4-not reached), 36.6 (33.4-not reached), and not reached, respectively, and overall survival in months (95% confidence intervals) of 40.8 (31.7-44.9), 54.4 (49.0-67.0), 64.3 (63.4-not reached), and not reached, respectively. There was a statistically significant correlation between greater depth of PSA decline and improved clinical outcomes, suggesting a previously underappreciated relationship between changes in PSA levels and clinical outcomes in nonmetastatic castration-resistant prostate cancer.

Diagnosis and management of gastroenteropancreatic neuroendocrine neoplasms by nuclear medicine: Update and future perspective.

Gastrointestinal (GI) cancers are the second most common cause of cancer related deaths in the World. Neuroendocrine neoplasms (NENs) is a rare tumor that originated from peptidergic neurons and neuroendocrine cells. NENs occurs in all parts of the body, especially in stomach, intestine, pancreas and lung. These rare tumors are challenging to diagnose at earlier stages because of their wide anatomical distribution and complex clinical features. Traditional imaging methods including magnetic resonance imaging (MRI) and computed tomography (CT) are mostly of useful for detection of larger primary tumors that are 1cm in size. A new medical imaging specialty called nuclear medicine uses radioactive substances for both diagnostic and therapeutic purposes. Nuclear medicine imaging relies on the tissue-specific uptake of radiolabeled tracers. Nuclear medicine techniques can easily identify the NENs tissues for their ability to absorb and concentrate amine, precursors, and peptides, whereas the traditional imaging methods are difficult to perform well. The somatostatin receptor (SSTR) is a targetable receptor frequently expressed in the gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs), and is a promising target for tumor-targeted therapies and radiography. SSTR based somatostatin receptor imaging and peptide receptor radionuclide therapy (PRRT) has emerged as a new hot subject in the diagnosis and treatment of GEP-NENs due to the rapid development of somatostatin analogues (SSAs) and radionuclide. This review aims to provide an overview of the current status of nuclear medicine imaging modalities in the imaging of GEP-NENs, and puts them in perspective of clinical practice.

PMON123 Diagnostically Challenging Case of Cushing's Syndrome from a Pancreatic Neuroendocrine Tumor Treated with Radiofrequency Ablation

Abstract Background The delayed diagnosis of Cushing's syndrome (CS) results in advanced disease, treatment delays and poor outcomes. We present a patient with ectopic ACTH-syndrome (EAS) from a pancreatic neuroendocrine tumor (NET) whose care posed significant diagnostic and therapeutic challenges. Clinical Case 59F with classic Cushing's stigmata (including striae, plethora, supraclavicular and dorsocervical fat pads, muscle wasting), and two-year history of rapid weight gain, hypertension, T2DM, hyperlipidemia, severe osteoporosis complicated by multiple vertebral compression fractures, presented for workup and management of ACTH dependent CS. CS was confirmed (Baseline: ACTH 96 [7.2-63.3 pg/ml], serum cortisol 19.6 [4.8 - 19.5 mcg/dL]; LDSST: cortisol 18.5 [&amp;lt;1.8 mcg/dL], dexamethasone 547 [&amp;gt;200 ng/dL]; 24-hour Urine Free Cortisol: 191.60 [&amp;lt;45 mcg/d], 24-hour Cr 484 mg/day; LNSC: 436, 464 [29-101 ng/dL]; 8 mg ODST cortisol 7.2 mcg/dL). Pituitary MRI showed possible 0.5 cm left anterior pituitary lesion. Inferior petrosal sinus sampling (IPSS) to differentiate between Cushing's disease and EAS was initially planned, however, her course was complicated by an NSTEMI and acute/subacute lacunar infarcts in the left parietal and frontal lobes, and IPSS was deemed contraindicated. Additional workup was pursued including POMC 154 [&amp;lt;40 fmol/ml], Chromogranin A 538 [0-103 ng/ml] (on pantoprazole), pancreatic polypeptide 798 [0 - 435 pg/mL], 24-hour 5HIAA/Creatinine 3 [0 - 15 mg/24hr]. Chest/Abdominal/Pelvis CT showed a 1.5 cm incidental lipid rich adrenal adenoma; workup was negative for pheochromocytoma/ Conn's tumor/ adrenocortical carcinoma. Given elevated POMC and clinical suspicion for EAS, the patient underwent 68Ga-DOTATATE PET-CT scan which revealed an avid 7 mm lesion (SUVmax 14.5) in the pancreatic tail suspicious for a pancreatic NET- the presumed ectopic source of ACTH. Given the patient's poor functional status she was not a candidate for tumoral resection via distal pancreatectomy. Ketoconazole was initiated for treatment of hypercortisolism with good biochemical control, but the patient developed liver toxicity. The decision was made to pursue endoscopic ultrasound guided biopsy and radiofrequency ablation of the lesion. Pathology confirmed ACTH immunoreactive low-grade pancreatic NET. Post-procedure, morning ACTH was 8 pg/ml and cortisol was 9.1 mcg/dL, and the patient required steroids for relative adrenal insufficiency. Further follow up with repeat POMC, cortisol, ACTH levels, 24-hour UFC is required to monitor response. Conclusion IPSS is the gold standard test for differentiating Cushing's disease from EAS but is only available in select centers and for suitable candidates. This case supports the potential utility of POMC peptide measurements in the differential diagnosis of CS and the use of advanced nuclear imaging modalities for tumor localization. For patients with functional pNET who are poor surgical candidates or intolerant of pharmacotherapy, novel endoscopic ablation may offer a lower risk therapeutic option and its use should be further investigated. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Diagnostic Strategy and Prognostic Factors for Ectopic Adrenocorticotropic Hormone Syndrome: A Retrospective Study of 64 Cases

Introduction: Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a serious life-threatening disease. Tumor localization is crucial in EAS management. This underscores the importance of evaluating imaging methods and prognostic factors to provide a clear basis for patient diagnosis and management. Objective: The aim of this study was to investigate imaging methods and analyze the relevant prognostic factors for EAS. Methods: The retrospective study followed 64 cases of EAS diagnosed between 1992 and 2020. Clinical features, biochemical analysis, and imaging studies were collected, and survival data were followed up and analyzed. Results: Of 64 patients, 41% were female with a mean (±SD) age at diagnosis of 47 ± 16 years. Computed tomography (CT), 18-F fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)-CT, and octreotide scintigraphy had similar sensitivity in localizing ectopic ACTH-secreting tumors. However, in cases with negative imaging on CT, both of ¹⁸F-FDG PET-CT and octreotide scintigraphy further localized 25% tumors. The combination of all three modalities failed to further increase the sensitivity. Patients with thymic tumors survived longer than those with pulmonary or pancreatic tumors (p = 0.013 and 0.047, respectively). Multivariate analyses showed that hypokalemia (p = 0.004) and treatment modality (p = 0.048) were independent prognostic factors. The optimal serum potassium cutoff based on maximum log-rank statistics (p = 0.012) was 2.90 mmol/L. Conclusion: CT is the first choice for tumor localization in EAS. CT in combination with a nuclear medicine or molecular imaging modality is necessary for further identification of an ectopic source. Serum potassium <2.90 mmol/L is associated with shorter overall survival, and tumor resection plays the most important role in the survival improvement.

Systematic Review: Targeted Molecular Imaging of Angiogenesis and Its Mediators in Rheumatoid Arthritis

Extensive angiogenesis is a characteristic feature in the synovial tissue of rheumatoid arthritis (RA) from a very early stage of the disease onward and constitutes a crucial event for the development of the proliferative synovium. This process is markedly intensified in patients with prolonged disease duration, high disease activity, disease severity, and significant inflammatory cell infiltration. Angiogenesis is therefore an interesting target for the development of new therapeutic approaches as well as disease monitoring strategies in RA. To this end, nuclear imaging modalities represent valuable non-invasive tools that can selectively target molecular markers of angiogenesis and accurately and quantitatively track molecular changes in multiple joints simultaneously. This systematic review summarizes the imaging markers used for single photon emission computed tomography (SPECT) and/or positron emission tomography (PET) approaches, targeting pathways and mediators involved in synovial neo-angiogenesis in RA.

Performance Evaluation of the Nuclear Medicine Imaging Modalities at NINMAS

Performance evaluation of the imaging systems of nuclear medicine have been checked and compared with the previous data which were collected at the time of acceptance testing at the National Institute of Nuclear Medicine &amp; Allied Sciences (NINMAS). Performance measurements that have been carried out for the SPECT and SPECT-CT system recently were according to NEMA NU 2-2012 standard and IAEA Human Health Series No.1. Phantoms required for these tests to be performed were supplied by the vendors. Performance tests checked for the SPECT system were intrinsic flood field uniformity, intrinsic spatial resolution, center of rotation (COR), offset and alignment of axes, sensitivity and total performance test. The CT Phantom tests have been carried out for the visual inspection of resolution, contrast, noise and uniformity of the CT system. In these studies, performance evaluations of nuclear medicine imaging modalities including SYMBIA Evo Excel Dual Head SPECT Scanners, SYMBIA T16 SPECT-CT System and Nucline TH-45 Single Head Gamma Camera for Thyroid have been done to ensure the quality of service given to the patients. Performance measurements of these imaging modalities have shown satisfactory image quality. All data were compared with the acceptance testing data which were carried out during installation at the institute. Bangladesh J. Nuclear Med. 25(1): 28-35, 2022