Imaging in neuroendocrine tumors: an update for the clinician

[Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH)]

INTRODUCTION

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is a rare, chronic condition that predominantly affects women over the age of 60.

CURRENT KNOWLEDGE

DIPNECH combines non-specific clinical signs (chronic cough, dyspnea), bronchial obstruction on PFT and signs suggestive of bronchiolitis on chest CT associated with nodules and multiple micronodules. The diagnosis is most often histological, associating neuroendocrine cell hyperplasia, tumorlets and, inconsistently, carcinoid tumors and constrictive bronchiolitis.

PROSPECTS

There are currently no recommendations for DIPNECH treatment and the literature is limited to case reports and retrospective series. Inhibitors of mTOR and somatostatin analogs are possible treatments requiring validation by clinical trials. Functional follow-up and CT scan monitoring are necessary in order to detect complications.

CONCLUSIONS

DIPNECH is a rare, usually insidious pathology, and may in some cases expose the patient to a risk of tumor and chronic respiratory failure. The diagnosis should be made in the event of a chronic cough in a middle-aged woman.

Ectopic GHRH production: revisiting a rare cause of acromegaly

Growth Hormone-Releasing Hormone (GHRH) is a hypothalamic hormone that stimulates GH secretion by the anterior pituitary gland. Ectopic production of GHRH by neuroendocrine tumors (NETs) is a rare cause of acromegaly, with some clinical and biochemical features indistinguishable from pituitary adenoma origin. Some clues for this diagnosis include pituitary MRI harboring hyperplasia, increased serum GHRH and extra-pituitary tumor detected in whole body scans. The preferable treatment, when possible, should be surgical resection of the NET. In cases with residual tumor, somatostatin analogs could be used as an alternative for adjuvant therapy for both tumoral and biochemical control of IGF-1. Life-long follow-up is needed as some patients may develop persistent pituitary hyperplasia or GH-adenomas due to prolonged GHRH exposure, with elevated IGF-1 levels even without NET recurrence. In such scenarios, medical therapy should be provided for hyperplasia cases and transsphenoidal surgery to patients with pituitary adenoma. If available, genetic test for MEN1 mutations should always be performed.

Full-Body Tumor Response Heterogeneity of Metastatic Neuroendocrine Tumor Patients Undergoing Peptide Receptor Radiopharmaceutical Therapy

Patients with metastatic neuroendocrine tumors (NETs) can present with hundreds of lesions, and each lesion might have a unique response pattern to peptide receptor radiopharmaceutical therapy (PRRT). This response heterogeneity has been observed but is poorly understood. In this work, we perform a quantitative analysis of longitudinal PET/CT scans to comprehensively characterize the NET response to PRRT. Methods: NET patients treated with [177Lu]Lu-DOTATATE PRRT imaged at baseline, during, and after PRRT with [68Ga]Ga-DOTATATE PET/CT were enrolled in this retrospective single-institutional study. A deep-learning model was used to identify and contour regions of nonphysiological elevated tracer uptake (lesion-regions of interest [ROIs]). An automated analysis was performed to identify, contour, and quantify the individual lesion-ROI uptake, match ROI between time points, and categorize each lesion-ROI as disappearing, decreasing (ΔSUVtotal < -30%), stable (-30% ≤ ΔSUVtotal ≤ 30%), increasing (ΔSUVtotal > 30%), or new. A patient was considered to have response heterogeneity if both new or increasing lesion-ROIs and decreasing or disappearing lesion-ROIs were present after therapy. Results: Eighteen patients who received between 2 and 7 [68Ga]Ga-DOTATATE PET/CT scans were enrolled. In total, 3,289 lesion-ROIs were contoured in the 67 scans acquired (median of 24 lesion-ROIs per image), and 1,459 lesion-ROI tracks, defined as the path that each unique lesion-ROI follows across all time points, were determined by the ROI tracking method (median of 49 tracks per patient). All patients presented with disease response heterogeneity at the first follow-up scan. All 10 patients with more than 1 follow-up scan showed nonmonotonic change in lesion-ROI uptake. Of 129 tracks containing new lesion-ROIs at the first follow-up, 80 (62%) eventually resolved on final follow-up, whereas only 12% (7/60) of the tracks with lesion-ROIs disappearing at the first follow-up scan returned on final follow-up. Conclusion: To the best of our knowledge, this is the first study to evaluate response comprehensively and quantitatively in terms of individual lesion-ROIs. Response heterogeneity was observed in 100% of the patients, which suggests that comprehensive, lesion-level, response assessment is vital for the accurate understanding of the NET response to PRRT.

ESR Essentials: role of PET/CT in neuroendocrine tumors-practice recommendations by the European Society for Hybrid, Molecular and Translational Imaging

Neuroendocrine neoplasms (NEN) originate from the secretory cells of the neuroendocrine system, with the majority arising in the gastrointestinal tract and pancreas. Given the heterogeneity in the biological behavior and morphological differentiation of these tumors, advanced imaging techniques are crucial for supporting the suspected diagnosis, accurate staging, and monitoring therapy. As most well-differentiated NEN demonstrate overexpression of somatostatin receptors (SSR) on the cell surface, SSR-directed PET/CT is considered the reference standard for imaging of this particular entity. SSR-PET/CT should be the imaging method of choice in every NEN G1 or G2 and considered for re-staging after both potentially curative and non-curative surgeries. The extent of SSR expression is also crucial for determining a patient's eligibility for peptide receptor radionuclide therapy (PRRT). PRRT utilizes [177Lu]Lu-DOTA-TATE to target the SSR receptor and can significantly prolong progression-free survival in patients with advanced, progressive neuroendocrine tumor of the gastroenteropancreatic system (GEP-NET). PET/CT is a central component of the multidisciplinary management of NEN. Variable follow-up intervals are recommended, considering that tumors with higher proliferation rates or advanced metastatic disease require more frequent assessments. The combination with other imaging modalities, like MRI, complements SSR-PET/CT, further enhancing overall diagnostic accuracy. KEY POINTS: Somatostatin receptor-PET/CT (SSR-PET/CT) is the guideline-recommended reference standard for imaging well-differentiated neuroendocrine tumors (NET). SSR-PET/CT should be the diagnostic imaging of choice for staging and post-therapy re-staging of grade 1 or 2 NET (G1 or G2). Variable follow-up intervals are recommended for NET G1 and G2. Tumors with higher proliferation rates or advanced metastatic disease necessitate more frequent assessments.

Characteristics and outcomes of observed versus resected pancreatic neuroendocrine tumors

Background

Pancreatic neuroendocrine tumors (pNETs) are a rare group of tumors with a wide range of clinical presentations. pNETs may present as incidentally discovered slow-growing tumors or as more aggressive tumors with metastatic potential. The mainstay of treatment is surgical resection; however, some have argued that observation can be considered for small, nonfunctional tumors. The objective of this study was to compare patients with pNETs who underwent initial resection versus observation to better understand tumor characteristics that favor either treatment approach.

Methods

A retrospective review was performed of patients diagnosed with pNETs at a tertiary referral center from 2018 to 2023. Information on the patient and tumor, disease and treatment course, and outcomes was collected.

Results

Forty-three patients were included in the study; 33% underwent initial resection, 37% underwent observation, and 30% underwent surgical resection following a period of observation (delayed resection). Patients who underwent initial resection were more likely to be younger with fewer comorbidities and have symptomatic or functional tumors. Patients with tumors >2 cm were more likely to have a postoperative complication. In a subgroup of patients with incidentally discovered tumors ≤2 cm, 33% underwent delayed resection and did not experience any postoperative complications; 66% underwent observation, and none had progression of their disease over the follow-up period of 17 months.

Conclusion

While surgical resection remains the mainstay of treatment for pNETs, a period of observation in select individuals with small, incidentally discovered pNETs may also be considered safe. Management with surgical resection or initial observation must be an individualized decision and may be optimally supported with formal multidisciplinary tumor board discussion.

Primary intracranial neuroendocrine tumor at the sphenoid ridge with metastasis to the spinal cord: A case report

RATIONALE

Neuroendocrine tumors (NETs) originate from neuroendocrine cells and they are depicted with both nerve cells as well as hormone-producing cells. These tumors were initially discovered in extracranial locations and central nervous system involvement is often a result of metastasis. Herein, we present a very rare case of primary intracranial neuroendocrine tumor (PINET) that masqueraded as meningioma at the sphenoid ridge with metastasis to the spinal cord in a patient without a known history of extracranial NET at the time of diagnosis.

PATIENT CONCERNS

A 52-year-old male presented with a 2-month history of headache and decreased vision in the left eye accompanied by inarticulation in speech for 1 month.

DIAGNOSES

Magnetic resonance imaging of the head showed a space-occupying lesion in the left sphenoid ridge which was mistaken for meningioma.

INTERVENTIONS

The lesion was surgically resected and immunohistochemical evaluation revealed PINET. Postoperative positron emission tomography scan and magnetic resonance imaging of the thoracolumbar spine detected a tumor nodule in the thoracolumbar region which was a metastatic tumor. The metastatic lesion at the thoracolumbar spine was surgically resected and spinal fixation was carried out to stabilize the spine. Immunohistochemical evaluation of the spinal lesion also confirmed NET. He was further treated with several cycles of adjuvant chemotherapy and radiotherapy.

OUTCOMES

Two years' follow-up revealed no recurrence of the tumor and he is currently well. However, we are still following the patient because of the nature of the tumor.

LESSON

PINET may be capable of metastasizing to spinal cord.

Role of advanced imaging in primary hepatic neuroendocrine tumor with borderline raised AFP and negative chromogranin staining: A case report

BACKGROUND

Primary hepatic neuroendocrine tumors (PHNETs) are rare, accounting for approximately 0.3 % of all neuroendocrine tumors (NETs) and are often difficult to diagnose due to their nonspecific symptoms and imaging features. Standard diagnostic and treatment protocols are lacking due to their rarity, but imaging and immunohistochemistry (IHC) remain key tools for diagnosis.

CASE REPORT

A 68-year-old male presented with abdominal discomfort and loss of appetite. Imaging revealed a large exophytic mass in the left lobe of the liver. After ruling out extrahepatic primary sources, a left lobe hepatectomy was performed. Histopathology confirmed the diagnosis of PHNET, with positive IHC staining for synaptophysin and CK-7. Postoperative PET-CT ruled out any distant metastases. The patient had an uneventful recovery.

DISCUSSION

PHNETs are believed to originate from ectopic neuroendocrine cells in the liver, though several theories exist. Imaging alone cannot conclusively diagnose PHNETs, as they mimic other hepatic tumors like hepatocellular carcinoma. Histopathological examination, along with IHC markers like chromogranin and synaptophysin, is essential for diagnosis. Surgical resection remains the treatment of choice, with good outcomes despite the risk of recurrence. Non-surgical therapies, such as chemotherapy or ablation, are under investigation but lack consensus.

CONCLUSION

PHNETs are rare and challenging to diagnose, requiring imaging and IHC for confirmation. Surgery offers the best prognosis, making personalized, surgery-centered treatment plans essential for management. Comprehensive follow-up, including functional imaging, is necessary to monitor recurrence or metastasis.

Neuroendocrine carcinoma of the adrenal gland: A rare case report and literature review

Neuroendocrine carcinoma (NEC) presence in the adrenal glands is rare. Neuroendocrine carcinoma manifests across a wide range of clinical presentations, from asymptomatic cases to those characterized by hormone overproduction or the tumor's mass effect. We report a 48-year-old male referred by a urology specialist with a chief complaint of right-sided back pain for the past 6 months accompanied by nausea, vomiting, and sharp stabbing headaches. The patient had a history of right adrenalectomy surgery. Elevated blood pressure of 150/110 mmHg, and no abnormalities found. The radiologist found a solid lesion and cyst at the lower pole of the right kidney and observed multiple recurrent tumors in the right adrenal on the MRI examination. The biopsy revealed poorly differentiated carcinoma and adrenocortical carcinoma tissue on the second biopsy 2 months later. The patient was diagnosed with neuroendocrine carcinoma; the patient underwent a biopsy guided by CT, followed by a pathological assessment (PA). The surgeon carried out the tumor removal surgery and performed an immunohistochemical (IHC) analysis. A 3-month follow-up is planned to evaluate the potential need for adjuvant chemotherapy. The case underscores the importance of accurate pathological diagnosis and multimodal management in recurrent adrenal tumors, particularly when considering NEC as a differential diagnosis.

Clinical management of typical and atypical carcinoids/neuroendocrine tumors in ENETS centres of excellence (CoE): Survey from the ENETS lung NET task force

Lung carcinoid tumours are neuroendocrine neoplasms originating from the bronchopulmonary tract's neuroendocrine cells, accounting for only 1%-3% of all lung cancers but 30% of all neuroendocrine tumours. The incidence of lung carcinoids, both typical and atypical, has been increasing over the years due to improved diagnostic methods and increased awareness among clinicians and pathologists. The most recent WHO classification includes a subgroup of lung carcinoids with atypical morphology and higher mitotic count and/or Ki67 labelling index. Despite appropriate surgery, the 5-year survival rate for atypical carcinoids barely exceeds 50%-70%. The role of adjuvant therapy in lung carcinoids is not well-defined, and clinical decisions are generally based on the presence of high-risk features. Long-term follow-up is essential to monitor for recurrence, although the optimal follow-up protocol remains unclear. To address the lack of consensus in clinical management decisions, the European Neuroendocrine Tumor Society (ENETS) initiated a survey among 20 expert centres. The survey identified varied opinions on approaches to imaging, surgery, use of adjuvant therapy, and follow-up protocols. Notably, the absence of dedicated multidisciplinary lung neuroendocrine tumour boards in some centres was evident. Experts agreed on the need for a prospective adjuvant trial in high-risk patients, emphasizing the feasibility of such a study. In conclusion, the study highlights the need for a more uniform adoption of existing guidelines in the management of lung carcinoid tumours and emphasizes the importance of international collaboration to advance research and patient care. Close collaboration between healthcare providers and patients is vital for effective long-term surveillance and management of these rare tumours.

Diagnostic Approaches to Neuroendocrine Neoplasms of Unknown Primary Site

ABSTRACT

Neuroendocrine tumors (NETs) are relatively uncommon heterogeneous neoplasms arising from endocrine and neuronal origin cells showing highly variable clinical behavior. By the time these tumors are discovered, up to 14% of patients with histologically proven NETs have metastasis, with the liver as the most frequently affected organ. Sometimes, no known primary site can be identified via routine imaging. Neuroendocrine tumors of unknown origin carry a poorer prognosis (compared with metastatic NETs with a known primary site) because of a lack of tailored surgical intervention and appropriate medical therapy (eg, chemotherapy or targeted therapy). A multimethod approach is frequently used in the trial to accurately determine the primary site for NETs of unknown primary sites and may include clinical, laboratory, radiological, histopathological, and surgical data. New molecular techniques using the genomic approach to identify the molecular signature have shown promising results. Various imaging modalities include ultrasound, computed tomography (CT), dual-energy CT, magnetic resonance imaging, and functional and hybrid imaging (positron emission tomography/CT, positron emission tomography/magnetic resonance imaging); somatostatin receptor imaging with new tracers is frequently used in an attempt for localization of the primary site.

eTFC-01: a dual-labeled chelate-bridged tracer for SSTR2-positive tumors

BACKGROUND

Integrating radioactive and optical imaging techniques can facilitate the prognosis and surgical guidance for cancer patients. Using a single dual-labeled tracer ensures consistency in both imaging modalities. However, developing such molecule is challenging due to the need to preserve the biochemical properties of the tracer while introducing bulky labeling moieties. In our study, we designed a trifunctional chelate that facilitates the coupling of the targeting vector and fluorescent dye at opposite sites to avoid undesired steric hindrance effects. The synthesis of the trifunctional chelate N3-Py-DOTAGA-(tBu)3 (7) involved a five-step synthetic route, followed by conjugation to the linear peptidyl-resin 8 through solid-phase synthesis. After deprotection and cyclization, the near-infrared fluorescent dye sulfo-Cy.5 was introduced using copper free click chemistry, resulting in eTFC-01. Subsequently, eTFC-01 was labeled with [111In]InCl3. In vitro assessments of eTFC-01 binding, uptake, and internalization were conducted in SSTR2-transfected U2OS cells. Ex-vivo biodistribution and fluorescence imaging were performed in H69-tumor bearing mice.

RESULTS

eTFC-01 demonstrated a two-fold higher IC50 value for SSTR2 compared to the gold standard DOTA-TATE. Labeling of eTFC-01 with [111In]InCl3 gave a high radiochemical yield and purity. The uptake of [111In]In-eTFC-01 in U2OS.SSTR2 cells was two-fold lower than the uptake of [111In]In-DOTA-TATE, consistent with the binding affinity. Tumor uptake in H69-xenografted mice was lower for [111In]In-eTFC-01 at all-time points compared to [111In]In-DOTA-TATE. Prolonged blood circulation led to increased accumulation of [111In]In-eTFC-01 in highly vascularized tissues, such as lungs, skin, and heart. Fluorescence measurements in different organs correlated with the radioactive signal distribution.

CONCLUSION

The successful synthesis and coupling of the trifunctional chelate to the peptide and fluorescent dye support the potential of this synthetic approach to generate dual labeled tracers. While promising in vitro, the in vivo results obtained with [111In]In-eTFC-01 suggest the need for adjustments to enhance tracer distribution.

Clinical features and prognosis of malignant small bowel tumors: Experience from a university hospital in Chile

BACKGROUND

Small bowel tumors (SBT) are infrequent and represent a small proportion of digestive neoplasms. There is scarce information about SBT in Latin America.

AIM

To describe the epidemiology, clinical characteristics, diagnostic methods, and survival of malignant SBTs.

METHODS

Retrospective observational study of adult patients with histopathological diagnosis of SBT between 2007 and 2021 in a university hospital in Chile.

RESULTS

A total of 104 patients [51.9% men; mean age 57 years] with SBT. Histological type: neuroendocrine tumor (NET) (43.7%, n=38), gastrointestinal stromal tumors (GIST) (21.8%, n=19), lymphoma (17.2%, n=15) and adenocarcinoma (AC) (11.5%, n=10). GIST was more frequent in duodenum (50%; n=12) and NET in the ileum (65.8%; n=25). Metastasis was observed in 17 cases, most commonly from colon and melanoma. Nausea and vomiting were significantly more often observed in AC (p=0.035), as well as gastrointestinal bleeding in GIST (p=0.007). The most common diagnostic tools were CT and CT enteroclysis with an elevated diagnostic yield (86% and 94% respectively). The 5-year survival of GIST, NET, lymphoma and AC were 94.7% (95%CI: 68.1-99.2), 82.2% (95%CI: 57.6-93.3), 40.0% (95%CI: 16.5-82.8) and 25.9% (95%CI: 4.5-55.7%), respectively. NET (HR 6.1; 95%CI: 2.1-17.2) and GIST (HR 24.4; 95%CI: 3.0-19.8) were independently associated with higher survival compared to AC, adjusted for age and sex.

CONCLUSIONS

Malignant SBT are rare conditions and NETs are the most common histological subtype. Clinical presentation at diagnosis, location or complications may suggest a more probable diagnosis. GIST and NET are associated with better survival compared to other malignant subtypes.

Benign or by Chance: A Case Report on Incidental Appendectomy Revealing a Neuroendocrine Tumor During Traumatic Exploratory Laparotomy

Incidental appendectomies (IAs) are often performed in laparotomies to prevent future complications caused by the buildup of scar tissue. Although neoplastic findings are rare, all appendectomy specimens should be sent for histopathological analysis. We present the case of a 38-year-old man found to have an appendiceal neuroendocrine tumor (NET) after receiving an IA secondary to a traumatic rectal perforation requiring exploratory laparotomy. Well-differentiated NETs isolated to the appendix have an excellent prognosis. Appendectomies are considered curative for NETs smaller than 2 cm that have not metastasized beyond the appendix. Appendiceal NETs are capable of secreting vasoactive substances and, therefore, causing carcinoid syndrome. However, the progression to carcinoid syndrome generally coincides with metastasis to the liver, indicating a poor prognosis. While histopathological analysis of appendectomy specimens rarely yields atypical findings, this analysis is crucial to ensure that the proper treatment is selected based on tumor progression in an appendectomy specimen staining positive for somatotropin and chromogranin.

US, MRI, CT Performance and Interpretation of Uterine Masses

Uterine masses are commonly encountered as incidental findings during cross-sectional imaging or when individuals present with symptoms such as pain and bleeding. The World Health Organization categorizes tumors of the uterine corpus into 5 distinct groups: endometrial epithelial tumors and their precursors, tumor-like growths, mesenchymal uterine tumors, tumors with a combination of epithelial and mesenchymal elements, and various other types of tumors. The primary imaging method for assessing uterine abnormalities is transvaginal ultrasound. However, magnetic resonance imaging (MRI) can be employed to enhance the visualization of soft tissues, enabling a more detailed characterization of uterine masses. This article aims to outline the imaging features of both benign and malignant uterine masses using ultrasound, MRI, and computed tomography.

Neuroendocrine tumor of the gall bladder: A rare case report with review of literature

Neuroendocrine tumor of the gall bladder is an extremely rare malignancy, accounting for only 0.2% of all neuroendocrine tumors. Gall Bladder-Neuroendocrine Tumors (GB-NETs) are mainly diagnosed on histological examination of GB samples after cholecystectomy or after any biliary pathology surgery since it is very difficult to diagnose based on imaging. The overall outcome of gallbladder NET is worse than the adenocarcinoma of the gallbladder. No focused approach towards its treatment is available in literature due to its rarity. We share our experience of gall bladder NET in a 37-year-old female who was successfully managed at our institution.

PET reporter systems for the brain

Positron emission tomography (PET) can be used as a noninvasive method to longitudinally monitor and quantify the expression of proteins in the brain in vivo. It can be used to monitor changes in biomarkers of mental health disorders, and to assess therapeutic interventions such as stem cell and molecular genetic therapies. The utility of PET monitoring depends on the availability of a radiotracer with good central nervous system (CNS) penetration and high selectivity for the target protein. This review evaluates existing methods for the visualization of reporter proteins and/or protein function using PET imaging, focusing on engineered systems, and discusses possible approaches for future success in the development of high-sensitivity and high-specificity PET reporter systems for the brain.

Virus-associated neuroendocrine cancers: Pathogenesis and current therapeutics

Neuroendocrine neoplasms (NENs) comprise malignancies involving neuroendocrine cells that often lead to fatal pathological conditions. Despite escalating global incidences, NENs still have poor prognoses. Interestingly, research indicates an intricate association of tumor viruses with NENs. However, there is a dearth of comprehension of the complete scenario of NEN pathophysiology and its precise connections with the tumor viruses. Interestingly, several cutting-edge experiments became helpful for further screening of NET for the presence of polyomavirus, Human papillomavirus (HPV), Kaposi sarcoma-associated herpesvirus (KSHV), Epstein Barr virus (EBV), etc. Current research on the neuroendocrine tumor (NET) pathogenesis provides new information concerning their molecular mechanisms and therapeutic interventions. Of note, scientists observed that metastatic neuroendocrine tumors still have a poor prognosis with a palliative situation. Different oncolytic vector has already demonstrated excellent efficacies in clinical studies. Therefore, oncolytic virotherapy or virus-based immunotherapy could be an emerging and novel therapeutic intervention. In-depth understanding of all such various aspects will aid in managing, developing early detection assays, and establishing targeted therapeutic interventions for NENs concerning tumor viruses. Hence, this review takes a novel approach to discuss the dual role of tumor viruses in association with NENs' pathophysiology as well as its potential therapeutic interventions.

Magnetic Resonance Imaging of the Gastrointestinal Tract: Current Role, Recent Advancements and Future Prospectives

This review focuses on the role of magnetic resonance imaging (MRI) in the evaluation of the gastrointestinal tract (GI MRI), analyzing the major technical advances achieved in this field, such as diffusion-weighted imaging, molecular imaging, motility studies, and artificial intelligence. Today, MRI performed with the more advanced imaging techniques allows accurate assessment of many bowel diseases, particularly inflammatory bowel disease and rectal cancer; in most of these diseases, MRI is invaluable for diagnosis, staging, and disease monitoring under treatment. Several MRI parameters are currently considered activity biomarkers for inflammation and neoplastic disease. Furthermore, in younger patients with acute or chronic GI disease, MRI can be safely used for short-term follow-up studies in many critical clinical situations because it is radiation-free. MRI assessment of functional gastro-esophageal and small bowel disorders is still in its infancy but very promising, while it is well established and widely used for dynamic assessment of anorectal and pelvic floor dysfunction; MRI motility biomarkers have also been described. There are still some limitations to GI MRI related to high cost and limited accessibility. However, technical advances are expected, such as faster sequences, more specific intestinal contrast agents, AI analysis of MRI data, and possibly increased accessibility to GI MRI studies. Clinical interest in the evaluation of bowel disease using MRI is already very high, but is expected to increase significantly in the coming years.

Association between surveillance imaging and survival outcomes in small bowel neuroendocrine tumors

BACKGROUND

Surveillance guidelines following the resection of small bowel neuroendocrine tumors (SB-NETs) are inconsistent. We evaluated the impact of surveillance imaging on SB-NET recurrence and overall survival (OS).

METHODS

Patients with completely resected SB-NETs referred to a provincial cancer center (2004-2015) were reviewed. Associations between imaging frequency, recurrence, post-recurrence treatment, and OS were determined using univariate and Cox-regression analyses.

RESULTS

Among 195 completely resected SB-NET patients, 31% were ≥70 years, 43% were female, and 80% had grade 1 disease. Imaging frequency was predictive of recurrence (hazard ratio 2.52, 95% confidence interval 1.84-3.46, p < 0.001). 72% underwent interventions for recurrent disease. Patients who were treated for the recurrent disease had comparable OS to those who did not recur (median 152 vs. 164 months; p = 0.25). Imaging frequency was not associated with OS in those with treated recurrent disease (p = 0.65). Patients who recurred underwent more computerized tomography (CT) scans than those who did not recur (CT: 1.47 ± 0.89 vs. 1.02 ± 0.81 scans/year, p < 0.001). Detection of disease recurrence was 5%-7% per year during the first 6 years of surveillance and peaked at 17% in Year 9.

CONCLUSION

Less frequent imaging over a longer duration should be emphasized to capture clinically relevant recurrences that can be treated to improve OS.

Imaging Recommendations for Theranostic PET-CT in Oncology

We in this article have presented a review of the guideline recommendations on theranostic positron emission tomography-computed tomography (PET-CT) imaging which will be helpful to assist practitioners in providing appropriate patient care. Multiple guidelines by different societies and medical associations provide standards for diagnosis, imaging, and treatment of cancer patients. They have generated a number of recommendations related to 68Ga-DOTATATE and 68Ga-PSMA-11 PET-CT, which are the classical examples of theranostic PET-CT imaging in current practice.

Diagnostic Management of Gastroenteropancreatic Neuroendocrine Neoplasms: Technique Optimization and Tips and Tricks for Radiologists

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) comprise a heterogeneous group of neoplasms, which derive from cells of the diffuse neuroendocrine system that specializes in producing hormones and neuropeptides and arise in most cases sporadically and, to a lesser extent, in the context of complex genetic syndromes. Furthermore, they are primarily nonfunctioning, while, in the case of insulinomas, gastrinomas, glucagonomas, vipomas, and somatostatinomas, they produce hormones responsible for clinical syndromes. The GEP-NEN tumor grade and cell differentiation may result in different clinical behaviors and prognoses, with grade one (G1) and grade two (G2) neuroendocrine tumors showing a more favorable outcome than grade three (G3) NET and neuroendocrine carcinoma. Two critical issues should be considered in the NEN diagnostic workup: first, the need to identify the presence of the tumor, and, second, to define the primary site and evaluate regional and distant metastases. Indeed, the primary site, stage, grade, and function are prognostic factors that the radiologist should evaluate to guide prognosis and management. The correct diagnostic management of the patient includes a combination of morphological and functional evaluations. Concerning morphological evaluations, according to the consensus guidelines of the European Neuroendocrine Tumor Society (ENETS), computed tomography (CT) with a contrast medium is recommended. Contrast-enhanced magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI), is usually indicated for use to evaluate the liver, pancreas, brain, and bones. Ultrasonography (US) is often helpful in the initial diagnosis of liver metastases, and contrast-enhanced ultrasound (CEUS) can solve problems in characterizing the liver, as this tool can guide the biopsy of liver lesions. In addition, intraoperative ultrasound is an effective tool during surgical procedures. Positron emission tomography (PET-CT) with FDG for nonfunctioning lesions and somatostatin analogs for functional lesions are very useful for identifying and evaluating metabolic receptors. The detection of heterogeneity in somatostatin receptor (SSTR) expression is also crucial for treatment decision making. In this narrative review, we have described the role of morphological and functional imaging tools in the assessment of GEP-NENs according to current major guidelines.

Differential to Terminal Ileitis: Terminal Ileum Neuroendocrine Tumor Identified on Screening Colonoscopy

Background: Asymptomatic patients at average risk of developing colorectal cancer are encouraged to undergo screening colonoscopy beginning at age 45 years. While ileal intubation is often considered the gold standard for a complete colonoscopy, the relatively low diagnostic yield has prevented widespread adoption. Small bowel cancers, including neuroendocrine tumors, may present incidentally as terminal ileitis on routine colonoscopy with terminal ileum intubation. Neuroendocrine tumors, the most common primary neoplasm of the small intestine, are often asymptomatic or present as nonspecific abdominal pain in the sixth or seventh decade of life. Case Report: A 51-year-old asymptomatic male with unremarkable physical examination underwent screening colonoscopy that revealed scattered ulcerations of the terminal ileum. Immunohistochemistry of the lesion was consistent with well-differentiated neuroendocrine tumor, World Health Organization Grade I. DOTATATE positron emission tomography/computed tomography demonstrated avid adjacent right mesenteric lymph node and avid focal pancreatic body lesion. Fine-needle biopsy and immunohistochemistry of the pancreatic lesion confirmed neuroendocrine tumor, while the mesenteric lymph node was found to be benign. The patient underwent robotic-assisted ileocolic resection and has ongoing surveillance of the pancreatic lesion. Conclusion: Terminal ileitis encompasses a host of pathologic processes, including inflammatory states, infectious disease, malignancy, and vasculitis. Importantly, small bowel cancer is an increasing cause of terminal ileitis. Screening colonoscopy with ileal intubation can be a valuable tool for early detection of these lesions.

The incidence, prevalence, and survival analysis of pancreatic neuroendocrine tumors in the United States

PURPOSE

The incidence of pancreatic neuroendocrine tumors (pNETs) was increasing. The main purpose of this study was to statistically analyze the incidence and prevalence of pNETs and the main risk factors for the prognosis.

METHODS

Based on the Surveillance, Epidemiology, and End Results (SEER) database, with three registries integrated, this study comprehensively displayed the annual age adjust incidence of pNETs from 1975 to 2018, the estimated 20-year limited-duration prevalence, and conducted the univariate and multivariate survival analysis.

RESULTS

The incidence of pNETs has increased to about 1.5 per 100,000 population, and the prevalence has reached about 0.008% with the aged, Grade 1 and nonfunctional tumors accounting for the majority. The average median overall survival (OS), 5-year survival rate, and median disease-free survival (DFS) of pNETs patients from 1975 to 2018 were 85 months, 57.55%, and 220 months, respectively. From 2000 to 2018, the median OS was 94 months, and the 5-year survival rate was 59.94%. In multivariate survival analysis, the greatest risk factor was Grade 3&4 with HR = 3.62 (3.10-4.28), followed by distant stage with HR = 2.77 (2.28-3.36), and aged over 80 years old with HR = 2.26 (1.33-3.83). Surgery was a protective prognostic factor with HR = 0.34 (0.29-0.40).

CONCLUSION

The incidence and prevalence of pNETs were still increasing, but the trend was gradual and aging in recent years. The survival time of pNETs was longer but has not changed much in recent years. The degrees of malignancy, stage, and operation were the most important prognosis factors.

Metastatic Neuroendocrine Neoplasms of Unknown Primary: Clues from Pathology Workup

Simple Summary

While most neuroendocrine neoplasms are indolent and slow-growing tumors, subsets of cases will spread beyond the tissue of origin. Given the rather slow progress, some lesions are incidentally discovered as metastatic deposits rather than primary masses. In these cases, a biopsy is often taken to allow the pathologist to identify the tumor type and possibly the primary tumor site via microscopic examination. In this review, the authors present a simplified guide on how to approach metastatic neuroendocrine tumors from a pathologist’s perspective.

Abstract

Neuroendocrine neoplasms (NENs) are diverse tumors arising in various anatomical locations and may therefore cause a variety of symptoms leading to their discovery. However, there are instances in which a NEN first presents clinically as a metastatic deposit, while the associated primary tumor is not easily identified using conventional imaging techniques because of small primary tumor sizes. In this setting (which is referred to as a “NEN of unknown primary”; NEN-UP), a tissue biopsy is often procured to allow the surgical pathologist to diagnose the metastatic lesion. If indeed a metastatic NEN-UP is found, several clues can be obtained from morphological assessment and immunohistochemical staining patterns that individually or in concert may help identify the primary tumor site. Herein, histological and auxiliary analyses of value in this context are discussed in order to aid the pathologist when encountering these lesions in clinical practice.

The Diagnostic and Grading Accuracy of 68Ga-DOTATATE and 18F-FDG PET/MR for Pancreatic Neuroendocrine Neoplasms

Accurate diagnosis and grading are critical for pancreatic neuroendocrine neoplasm (pNEN) management. This study compares the diagnostic and grading value of ⁶⁸Ga-DOTATATE PET/MR and ¹⁸F-FDG PET/MR for pNENs separately as well as in combination. A total of 36 patients with histologically confirmed pNENs, who underwent both ⁶⁸Ga-DOTATATE PET/MR and ¹⁸F-FDG PET/MR within 2 weeks from 2020 to 2021, were retrospectively collected and analyzed. The maximum standardized uptake values of ⁶⁸Ga-DOTATATE (G-SUVmax) and ¹⁸F-FDG (F-SUVmax) on PET and the minimum values of apparent diffusion coefficient (ADCmin) on MR were measured on the lesions with known histological grading (25 by surgery, 11 by biopsy). Receiver-operating characteristic analysis was applied to determine the cutoffs of these parameters or their combinations for differentiation between G1 and G2, as well as between low-grade and high-grade pNENs. The Spearman rank correlation coefficient was used to assess the correlation between the imaging parameters and the maximum tumor diameters. The detection rate of ⁶⁸Ga-DOTATATE PET imaging alone was 95%, 87.5%, and 37.5% for G1, G2, and G3, respectively. Adding ¹⁸F-FDG PET or MR sequences of PET/MR increased the detection rate to 100% in all grades. Among the three parameters, G-SUVmax had the highest diagnostic rate in predicting tumor grade. It presented a sensitivity of 87.5% and a specificity of 80.0% with a cutoff value of 42.75 for differentiating G2 from G1 pNETs and a sensitivity and specificity of 100% and 71.4% with a cutoff value of 32.75 in predicting high-grade pNENs. The ratio of G-SUVmax to F-SUVmax (G-SUVmax/F-SUVmax) showed slight improvement in the diagnostic rate, while the product of G-SUVmax and ADCmin (G-SUVmax*ADCmin) did not improve the diagnostic rate. ⁶⁸Ga-DOTATATE PET/MR alone is sufficient for the diagnosis of pNENs and the prediction of various grades.

Gallbladder Neuroendocrine Carcinoma: A Case Report with Radiological–Pathological Correlation

Neuroendocrine tumors (NET) of the biliary system, specifically the gallbladder (GB), are extremely rare, accounting for only 0.2% of all NETs. The majority of GBNETs are discovered by chance during a histological examination of GB samples at autopsy, after cholecystectomy, or after surgery for other suspected biliary pathology. GBNETs are thought to develop from preexisting endocrine cells in the GB's neck or from induced endocrine cells caused by intestinal metaplasia of the body and fundus. We present a case of squamous cell carcinoma of the GB with neuroendocrine differentiation due to its rarity.

Therapeutic peptides: current applications and future directions

Peptide drug development has made great progress in the last decade thanks to new production, modification, and analytic technologies. Peptides have been produced and modified using both chemical and biological methods, together with novel design and delivery strategies, which have helped to overcome the inherent drawbacks of peptides and have allowed the continued advancement of this field. A wide variety of natural and modified peptides have been obtained and studied, covering multiple therapeutic areas. This review summarizes the efforts and achievements in peptide drug discovery, production, and modification, and their current applications. We also discuss the value and challenges associated with future developments in therapeutic peptides.

From chronic pruritus to neuroendocrine tumor: A case report

Chronic pruritus is a major and distressing symptom of many diseases of dermatological, neurological, psychogenic or systemic origin. This chronic itch could be a presenting sign of malignancy; therefore, paraneoplastic pruritus has also been associated with neuroendocrine tumors (NETs). This article focuses on a patient presenting with chronic pruritus for the past 12 months and who received numerous treatment schemes with very poor clinical improvement, that presented in the hospital for worsening of the chronic pruritus associated with skin rash and significant weight loss (approximately 6 kg over a 2-month period). The laboratory tests showed iron deficiency anemia, eosinophilia and negative tumor markers. In order to investigate the hypoanabolic and anemic syndromes, upper gastrointestinal endoscopy and colonoscopy, which showed no lesions or tumors, were employed. Skin biopsy was performed and antihistaminic and local steroid treatment was initiated. The patient's status worsened within a week and the patient was started on systemic steroid treatment with poor results. Computer tomography was performed to identify any tumor(s) located either in the pelvis or abdomen. A lesion was found in the terminal ileum, identified as a hypervascularized associating bulky lymphadenopathy. The patient was transferred to the surgical ward where right hemicolectomy with manual ileotransverse anastomosis L-L was performed. The histopathological result confirmed NET G2. The patient clinically improved, the skin lesions resolved and the itchiness disappeared. The general status improved significantly. NET G2 diagnosing was possible due to the atypic paraneoplastic sign: chronic pruritus. This case study highlights the association between itch and malignancy and presents an atypical way of NET presentation when all tumor markers remain negative.

Validation of SV2A-Targeted PET Imaging for Noninvasive Assessment of Neuroendocrine Differentiation in Prostate Cancer

Neuroendocrine prostate cancer (NEPC) is an aggressive and lethal variant of prostate cancer (PCa), and it remains a diagnostic challenge. Herein we report our findings of using synaptic vesicle glycoprotein 2 isoform A (SV2A) as a promising marker for positron emission tomography (PET) imaging of neuroendocrine differentiation (NED). The bioinformatic analyses revealed an amplified SV2A gene expression in clinical samples of NEPC versus castration-resistant PCa with adenocarcinoma characteristics (CRPC-Adeno). Importantly, significantly upregulated SV2A protein levels were found in both NEPC cell lines and tumor tissues. PET imaging studies were carried out in NEPC xenograft models with ¹⁸F-SynVesT-1. Although ¹⁸F-SynVesT-1 is not a cancer imaging agent, it showed a significant uptake level in the SV2A⁺ tumor (NCI-H660: 0.70 ± 0.14 %ID/g at 50–60 min p.i.). The SV2A blockade resulted in a significant reduction of tumor uptake (0.25 ± 0.03 %ID/g, p = 0.025), indicating the desired SV2A imaging specificity. Moreover, the comparative PET imaging study showed that the DU145 tumors could be clearly visualized by ¹⁸F-SynVesT-1 but not ⁶⁸Ga-PSMA-11 nor ⁶⁸Ga-DOTATATE, further validating the role of SV2A-targeted imaging for noninvasive assessment of NED in PCa. In conclusion, we demonstrated that SV2A, highly expressed in NEPC, can serve as a promising target for noninvasive imaging evaluation of NED.

Ocular adnexal manifestations of neuroendocrine neoplasms: a case report and a major review

PURPOSE

To describe a patient with orbital neuroendocrine neoplasm (NEN)/carcinoid tumor and to review the clinical presentation, systemic work-up, histopathologic features, and outcome of all previously reported ocular adnexal (OA) NENs.

METHODS

A systematic literature review. PubMed/MEDLINE and Google Scholar databases were searched for all well-documented cases of OA NENs.

RESULTS

Final analysis yielded 94 patients with OA NENs, 50 females (53%) and 44 (47%) males with an average age of 63 years (range 14-86). Of 91 patients with known information, the most common presenting signs were proptosis (56/91, 61%) and visual disturbances (42/91, 47%), induced by a mass most commonly associated with an extraocular muscle (49/63, 78%). The majority of tumors (88/94, 94%) were metastases, most commonly from the gastrointestinal tract (52/88, 59%). OA NEN metastasis presented following detection of primary tumor in 73/94 (78%) patients (median time to metastasis 36 months, range 0-288 months) and as an initial manifestation of disease in 15/94 (16%) patients (median time to primary detection 18 months, range 1-108 months). Systemic work-up included extra-OA NEN biopsy (37/54, 69%), multimodal imaging (42/54, 78%), and other laboratory studies (32/54, 59%). Resection with or without adjuvant chemotherapy, radiotherapy, and biologics was the most common intervention for OA NENs (36/82, 44%). Of 67 patients with available follow-up, the median survival was 108 months (95% CI 55-161 months) and the absolute 5-year survival rate was 68%.

CONCLUSIONS

OA NENs are almost exclusively metastases and can precede detection of primary tumor by many months, requiring appropriate diagnostic work-up.

Progress in the Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous and orphan group of neoplasms that vary in their histology, clinical features, prognosis, and management. The treatment of PNETs is highly dependent on the stage at presentation, tumor grade and differentiation, presence of symptoms from hormonal overproduction or from local growth, tumor burden, and rate of progression. The US Food and Drug Administration has recently approved many novel treatments, which have altered decision making and positively impacted the care and prognosis of these patients. In this review, we focus on the significant progress made in the management of PNETs over the past decade, as well as the active areas of research. Expected final online publication date for the Annual Review of Medicine, Volume 73 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Biomarkers in Small Intestine NETs and Carcinoid Heart Disease: A Comprehensive Review

Simple Summary

Neuroendocrine tumors (NET), a heterogeneous group of tumors arising from neuroendocrine cells, often pose a diagnostic and therapeutic challenge for the clinician. Biomarkers can serve as a useful diagnostic, prognostic, and predictive tool in the management of these rare tumors. For years the field of NET biomarkers was mainly based on products se-creted by neuroendocrine tumor cells, however, during the last decade the development of nov-el multianalyte biomarkers has rapidly evolved the field. The aim of this review is to summa-rize the literature on the use and limitations of available NET biomarkers for the diagnosis and management of small intestine neuroendocrine tumors (SI-NETs) and carcinoid heart disease.

Abstract

Biomarkers remain a valuable tool for the diagnosis and management of Neuroendocrine tumors (NETs). Traditional monoanalyte biomarkers such as Chromogranin A (CgA) and 5-Hydrocyondoleacetic acid (5-HIAA) have been widely used for many years as diagnostic, predictive and prognostic biomarkers in the field of NETs. However, the clinical utility of these molecules often has limitations, mainly inherent to the heterogeneity of NETs and the fact that these tumors can often be non-secretory. The development of new molecular multianalyte biomarkers, especially the mRNA transcript based “NETest”, has rapidly evolve the field and gives the ability for a “liquid biopsy” which can reliably assess disease status in real time. In this review we discuss the use of established and novel biomarkers in the diagnosis and management of small intestine NETs and carcinoid heart disease.

Management of Small Bowel Neuroendocrine Tumors

Small bowel neuroendocrine tumors (SBNETS) are slow-growing neoplasms with a noted propensity toward metastasis and comparatively favorable prognosis. The presentation of SBNETs is varied, although abdominal pain and obstructive symptoms are the most common presenting symptoms. In patients with metastases, hypersecretion of serotonin and other bioactive amines results in diarrhea, flushing, valvular heart disease, and bronchospasm, termed carcinoid syndrome. The treatment of SBNETs is multimodal and includes surgery, liver-directed therapy, somatostatin analogues, targeted therapy, and peptide receptor radionuclide therapy.

Recent Advances in the Clinical Translation of Silicon Fluoride Acceptor (SiFA) 18F-Radiopharmaceuticals

The incorporation of silicon fluoride acceptor (SiFA) moieties into a variety of molecules, such as peptides, proteins and biologically relevant small molecules, has improved the generation of ¹⁸F-radiopharmaceuticals for medical imaging. The efficient isotopic exchange radiofluorination process, in combination with the enhanced [¹⁸F]SiFA in vivo stability, make it a suitable strategy for fluorine-18 incorporation. This review will highlight the clinical applicability of [¹⁸F]SiFA-labeled compounds and discuss the significant radiotracers currently in clinical use.

Doing Great With DOTATATE: Update on GA-68 DOTATATE Positron Emission Tomography/Computed Tomography and Magnetic Resonance Imaging for Evaluation of Sinonasal Tumors

ABSTRACT

Sinonasal tumors are relatively rare and radiographically challenging to evaluate due to their wide variety of pathologies and imaging features. However, sinonasal tumors possessing somatostatin receptor overexpression have the benefit of utilizing a multimodality anatomic and functional imaging for a more comprehensive evaluation. This is particularly evident with esthesioneuroblastoma, with computed tomography and magnetic resonance imaging defining the anatomic extent of the tumor, whereas somatostatin receptor imaging, particularly with gallium-68 DOTATATE positron emission tomography/computed tomography, is used to assess the presence of metastatic disease for staging purposes as well as in the surveillance for tumor recurrence. In addition, areas which accumulate gallium-68 DOTATATE are potentially amenable to treatment with peptide receptor radionuclide therapy. In this manner, a combined approach of anatomic and functional imaging is critical for optimal imaging evaluation and treatment strategy of patients with sinonasal tumors.

Postsurgical Presentation of Zollinger-Ellison Syndrome After Resection of Endometrioid Neuroendocrine Tumor

Zollinger–Ellison syndrome is a functional neuroendocrine tumor with inappropriate gastrin secretion and hyperchlorhydria causing severe peptic ulcer disease and chronic diarrhea. Although 70% of primary gastrinomas occur in the region of the duodenum, the diagnosis and localization of gastrinomas can be challenging because of small lesions that may arise functionally as lymph node metastases at initial presentation. We report a 76-year-old woman presenting with Zollinger–Ellison syndrome several months after surgical resection of endometrioid small cell neuroendocrine carcinoma and endometrioid adenocarcinoma.

Identification of Tumor-Specific MRI Biomarkers Using Machine Learning (ML)

The identification of reliable and non-invasive oncology biomarkers remains a main priority in healthcare. There are only a few biomarkers that have been approved as diagnostic for cancer. The most frequently used cancer biomarkers are derived from either biological materials or imaging data. Most cancer biomarkers suffer from a lack of high specificity. However, the latest advancements in machine learning (ML) and artificial intelligence (AI) have enabled the identification of highly predictive, disease-specific biomarkers. Such biomarkers can be used to diagnose cancer patients, to predict cancer prognosis, or even to predict treatment efficacy. Herein, we provide a summary of the current status of developing and applying Magnetic resonance imaging (MRI) biomarkers in cancer care. We focus on all aspects of MRI biomarkers, starting from MRI data collection, preprocessing and machine learning methods, and ending with summarizing the types of existing biomarkers and their clinical applications in different cancer types.

Chemical Promiscuity of Non-Macrocyclic Multidentate Chelating Ligands for Radiometal Ions: H4neunpa-NH2 vs H4noneunpa

A comparative investigation of two structurally related potentially nonadentate chelating ligands, H₄neunpa-NH₂ and H₄noneunpa, has been undertaken to examine the influence of bifunctionalization on their coordination chemistry and metal ion selectivity. Significantly improved synthetic routes for each compound have been developed, employing straightforward high-yielding strategies. Radiolabeling studies with [⁴⁴Sc]Sc³⁺, [¹¹¹In]In³⁺, [¹⁷⁷Lu]Lu³⁺, and [²²⁵Ac]Ac³⁺ revealed a sharp contrast between the affinity of each chelator for large radiometal ions. H₄noneunpa demonstrated highly effective coordination of [¹⁷⁷Lu]Lu³⁺ and [²²⁵Ac]Ac³⁺ achieving quantitative radiochemical yields (>98%) at ligand concentrations of 10^-6 M (room temperature (RT), 10 min), with excellent stability when challenged in human serum, while H₄neunpa-NH₂ was unable to complex either metal ion effectively. Nuclear magnetic resonance (NMR) spectroscopy was employed to explore the coordination chemistry of each chelating ligand with nonradioactive metal ions, spanning a range of ionic radii and coordination numbers. A comprehensive conformational analysis of each metal complex was undertaken using density functional theory (DFT) calculations to explore the coordination geometries and explain the discrepancy in binding characteristics. Theoretical simulations revealed notable differences in the coordination geometry and apparent denticity of each ligand, which together account for the observed selectivity in metal binding and have important implications for the future design of complexes based upon this framework to target large radiometal ion coordination.

CT-derived radiomic features to discriminate histologic characteristics of pancreatic neuroendocrine tumors

PURPOSE

To assess the ability of radiomic features (RF) extracted from contrast-enhanced CT images (ceCT) and non-contrast-enhanced (non-ceCT) in discriminating histopathologic characteristics of pancreatic neuroendocrine tumors (panNET).

METHODS

panNET contours were delineated on pre-surgical ceCT and non-ceCT. First- second- and higher-order RF (adjusted to eliminate redundancy) were extracted and correlated with histological panNET grade (G1 vs G2/G3), metastasis, lymph node invasion, microscopic vascular infiltration. Mann-Whitney with Bonferroni corrected p values assessed differences. Discriminative power of significant RF was calculated for each of the end-points. The performance of conventional-imaged-based-parameters was also compared to RF.

RESULTS

Thirty-nine patients were included (mean age 55-years-old; 24 male). Mean diameters of the lesions were 24 × 27 mm. Sixty-nine RF were considered. Sphericity could discriminate high grade tumors (AUC = 0.79, p = 0.002). Tumor volume (AUC = 0.79, p = 0.003) and several non-ceCT and ceCT RF were able to identify microscopic vascular infiltration: voxel-alignment, neighborhood intensity-difference and intensity-size-zone families (AUC ≥ 0.75, p < 0.001); voxel-alignment, intensity-size-zone and co-occurrence families (AUC ≥ 0.78, p ≤ 0.002), respectively). Non-ceCT neighborhood-intensity-difference (AUC = 0.75, p = 0.009) and ceCT intensity-size-zone (AUC = 0.73, p = 0.014) identified lymph nodal invasion; several non-ceCT and ceCT voxel-alignment family features were discriminative for metastasis (p < 0.01, AUC = 0.80-0.85). Conventional CT 'necrosis' could discriminate for microscopic vascular invasion (AUC = 0.76, p = 0.004) and 'arterial vascular invasion' for microscopic metastasis (AUC = 0.86, p = 0.001). No conventional-imaged-based-parameter was significantly associated with grade and lymph node invasion.

CONCLUSIONS

Radiomic features can discriminate histopathology of panNET, suggesting a role of radiomics as a non-invasive tool for tumor characterization.

TRIAL REGISTRATION NUMBER

NCT03967951, 30/05/2019.

Thymic Epithelial Neoplasms: Radiologic-Pathologic Correlation

Thymic epithelial neoplasms, as classified by the World Health Organization, include thymoma, thymic carcinoma, and thymic carcinoid. They are a rare group of tumors and are often diagnosed incidentally in the work-up of parathymic syndrome, such as myasthenia gravis, or when mass effect or local invasion causes other symptoms. In each of these scenarios, understanding the radiologic-pathologic relationship of these tumors allows clinical imagers to contribute meaningfully to management decisions and overall patient care. Integrating important imaging features, such as local invasion, and pathologic features, such as necrosis and immunohistochemistry, ensures a meaningful contribution by clinical imagers to the care team.

Radiopharmaceuticals for Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are a heterogeneous group of tumors that originate in endocrine tissues throughout the body. Peptide receptor radionuclide therapy (PRRT) has emerged as a promising therapeutic option for patients with locally advanced and/or metastatic disease refractory to standard of care treatment. The landmark international phase III NETTER-1 trial led to the approval of ¹⁷⁷Lu-DOTATATE (Lutathera) in the treatment of somatostatin receptor-positive gastroenteropancreatic NETs. Similarly, data from the multicenter, phase II Study IB12B led to the approval of meta-[¹³¹I]Iodo-Benzyl-Guanidine (^I31I-MIBG) for treatment of iobenguane scan-positive, unresectable, locally advanced or metastatic pheochromocytoma or paraganglioma. With the clinical approval of these novel radiopharmaceuticals for managing select patients with NETs, additional studies are needed to refine patient selection, predict and assess therapy response, and optimize radiopharmaceutical delivery and clinical outcomes.

THE ROLE OF TUMOR-SEEKING RADIOPHARMACEUTICALS IN THE DIAGNOSIS AND MANAGEMENT OF ADRENAL TUMORS

Context

The variety of tumor-seeking radiopharmaceuticals, which are currently in clinical use, may have a potential role as imaging agents for adrenal gland tumors, due to physiological characteristics of this organ.

Objective

The purpose of this study was to evaluate the diagnostic potential of ^99mTc-HYNIC-TOC, ^99mTc(V)-DMSA, and ^99mTc-MIBI in the assessment of adrenal tumors, by correlating with imaging findings and histopathologic results.

Design

The research is designed as a cross-sectional prospective study.

Patients and method

The study included 50 patients with adrenal tumors (19 hormone-secreting and 31 nonfunctioning) and 23 controls without adrenal involvement. In all patients, single-photon emission computed tomography (SPECT) was performed, using qualitative and semiquantitative analysis. The tumor to non-tumor tracer uptake was conducted by using a region-of-interest technique. Adrenal to background (A/B) ratio was calculated in all cases.

Results

^99mTc-HYNIC-TOC scintigraphy showed a high statistical significance between A/B ratios, while other two tracers resulted in a lower sensitivity, specificity and accuracy. Futhermore, ^99mTc-HYNIC-TOC could have a high diagnostic yield to detect adrenal tumors (the receiver-operating-characteristic curve analysis, A/B ratio cut-off value of 8.40).

Conclusion

A semiquantitative SPECT analysis showed that ^99mTc-HYNIC-TOC is a highly sensitive tumor-seeking agent for the accurate localization of adrenal tumors.

Clinical Heterogeneity of Ectopic ACTH Syndrome: A Long-Term Follow-Up Study

OBJECTIVE

Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a heterogeneous condition caused by neuroendocrine neoplasms (NENs) located in the lungs, thymus, or pancreas. Our purpose was to evaluate the long-term outcome of these patients.

METHODS

Retrospective study at a referral center. The charts of 164 patients with Cushing syndrome, followed at our center from 1993 to 2019, were analyzed.

RESULTS

EAS was found in 16 patients (9.75%, 9 women, mean age 36.01 years) who had been followed for a median of 72 months. The source of EAS was a NEN in 10 patients (8 bronchial and 2 thymic carcinoid tumors) and a mixed corticomedullary tumor, consisting of a pheochromocytoma and an adrenocortical carcinoma in 1 patient. In 2 of the 6 patients initially considered to have occult EAS, the source of the ACTH excess became apparent after adrenalectomy, whereas in the remaining 4 (25%) patients, it has remained occult. Of the 11 patients in whom resection of the NEN was attempted, 10 patients achieved an early remission (91%), but 4 (25%) of these patients had a recurrence during follow-up (biochemically and clinically silent in 2 patients). Three patients died (18.75%): the young woman with the mixed corticomedullary tumor, a man with a thymic NEN that evolved into a neuroendocrine (NE) carcinoma after 11 years of follow-up, and a woman with a bronchial NEN.

CONCLUSION

The course of EAS varies according to tumor type and grade. Some patients have a protracted course, whereas others may evolve into neuroendocrine carcinomas.

ABBREVIATIONS

ACTH = adrenocorticotropic hormone; CS = Cushing syndrome; CT = computed tomography; CV = coefficient of variation; EAS = ectopic ACTH syndrome; IQR = interquartile range; NEN = neuroendocrine neoplasm; SCCL = small cell carcinoma of the lung; TSS = transsphenoidal surgery; UFC = urinary free cortisol.

Constrictive bronchiolitis in diffuse idiopathic pulmonary neuroendocrine cell hyperplasia

Background

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is characterised by multifocal proliferation of neuroendocrine cells and belongs in the spectrum of pulmonary neuroendocrine tumours. Some patients with DIPNECH develop airflow obstruction but the relationship between the two entities remains unclear.

Methods

We performed a computer-assisted search of the Mayo Clinic's electronic medical records for biopsy-proven cases of DIPNECH. We extracted clinical, pulmonary function, imaging and histopathological data along with treatments and outcomes.

Results

Among 44 patients with DIPNECH 91% were female and the median age was 65 years (interquartile range 56–69 years); 73% were never-smokers. Overall, 38 patients (86%) had respiratory symptoms including cough (68%) and dyspnoea (30%); 45% were previously diagnosed to have asthma or COPD. Pulmonary function testing showed an obstructive pattern in 52%, restrictive pattern in 11%, mixed pattern in 9%, nonspecific pattern in 23%, and was normal in 5%. On chest computed tomography scan, 95% manifested diffuse nodules and 77% manifested mosaic attenuation. For management, 25% of patients were observed without pharmacological therapy, 55% received an inhaled bronchodilator, 41% received an inhaled corticosteroid, 32% received octreotide; systemic steroids, azithromycin, or combination chemotherapy was employed in four patients (9%). Of 24 patients with available follow-up pulmonary function tests, 50% remained stable, 33% worsened and 17% improved over a median interval of 21.3 months (interquartile range 9.7–46.9 months).

Conclusion

DIPNECH occurs mostly in women and manifests diffuse pulmonary nodules and mosaic attenuation on imaging. It is commonly associated with airflow obstruction due to constrictive bronchiolitis, which manifests limited response to current pharmacological therapy.

Diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH) is an under-recognised cause of obstructive lung disease in women. Constrictive bronchiolitis associated with DIPNECH manifests limited response to currently employed therapies.https://bit.ly/3c3RZoe

An Update on Gastroenteropancreatic Neuroendocrine Neoplasms: From Mysteries to Paradigm Shifts

Although neuroendocrine neoplasms (NEN) were once thought to be rare and mostly "benign" diseases, they are now being redefined in light of recently discovered molecular information. NENs constitute a spectrum of variably differentiated neoplasms, ranging from well-differentiated tumors with a protracted course over many years to very aggressive neuroendocrine carcinomas. Although the majority of NEN are non-functional lesions, some of these tumors, do produce a hormonal hypersecretion syndrome. Their reappraisal has led scientist to unveil previously unknown oncogenic pathways and connections that resulted in a new category in the International Classification of Diseases (ICD-11) and a revised version of the World Health Organization Classification (WHO 2018). Complex diseases like NEN require a multidisciplinary approach that includes the perspectives of endocrinologists, medical and surgical oncologists, radiation oncologists, imaging specialists and pathologists. There are currently virtually thousands of ongoing trials evaluating the efficacy and safety of several molecular targeted therapies. The purpose of this review was to critically evaluate recent information regarding the pathogenesis, diagnosis and treatment of NEN.

Vasoactive intestinal peptide-oma causing refractory diarrhea in a young woman

Vasoactive intestinal peptide (VIP)-secreting neuroendocrine tumors are an exceptionally rare cause of chronic diarrhea. We describe a 36-year-old woman presenting with a 2-year history of severe diarrhea and electrolyte derangements ultimately diagnosed with VIPoma.

Primary skull base neuroendocrine carcinoma—a case report and review of literature

Skull-based neuroendocrine carcinomas are rare tumors with only a few case reports in literature. Here we present an unusual case of primary neuroendocrine carcinoma of the skull in 60-year-old male which was proven on surgical biopsy. The imaging features of this rare tumor along with differential diagnosis are discussed with brief review of the literature.