The Impact of 68Ga-DOTATATE PET/CT Imaging on Management of Patients with Neuroendocrine Tumors: Experience from a National Referral Center in the United Kingdom

Imaging of Neuroendocrine Neoplasms; Principles of Treatment Strategies. What Referring Clinicians Want to Know

ABSTRACT

Neuroendocrine neoplasms (NENs) are a diverse group of tumors that express neuroendocrine markers and primarily affect the lungs and digestive system. The incidence of NENs has increased over time due to advancements in imaging and diagnostic techniques. Effective management of NENs requires a multidisciplinary approach, considering factors such as tumor location, grade, stage, symptoms, and imaging findings. Treatment strategies vary depending on the specific subtype of NEN. In this review, we will focus on treatment strategies and therapies including the information relevant to clinicians in order to undertake optimal management and treatment decisions, the implications of different therapies on imaging, and how to ascertain their possible complications and treatment effects.

Appendiceal Neuroendocrine Neoplasms: A Comprehensive Review

ABSTRACT

Appendiceal neuroendocrine neoplasm (NEN) is the most common adult appendiceal malignant tumor, constituting 16% of gastrointestinal NENs. They are versatile tumors with varying morphology, immunohistochemistry, secretory properties, and cancer genomics. They are slow growing and clinically silent, to begin with, or present with features of nonspecific vague abdominal pain. Most acute presentations are attributed clinically to appendicitis, with most cases detected incidentally on pathology after an appendectomy. Approximately 40% of them present clinically with features of hormonal excess, which is likened to the functional secretory nature of their parent cell of origin. The symptoms of carcinoid syndrome render their presence clinically evident. However, slow growing and symptomatically silent in its initial stages, high-grade neuroendocrine tumors and neuroendocrine carcinomas of the appendix are aggressive and usually have hepatic and lymph node metastasis at presentation. This review article focuses on imaging characteristics, World Health Organization histopathological classification and grading, American Joint Committee on Cancer/Union or International Cancer Control, European Neuroendocrine Tumor Society staging, European Neuroendocrine Tumor Society standardized guidelines for reporting, data interpretation, early-stage management protocols, and advanced-stage appendiceal NENs. Guidelines are also set for the follow-up and reassessment. The role of targeted radiotherapy, chemotherapy, and high-dose somatostatin analogs in treating advanced disease are discussed, along with types of ablative therapies and liver transplantation for tumor recurrence. The search for newer location-specific biomarkers in NEN is also summarized. Regarding the varying aggressiveness of the tumor, there is a scope for research in the field, with plenty of data yet to be discovered.

State-of-the-Art Hybrid Imaging of Neuroendocrine Neoplasms

ABSTRACT

Neuroendocrine neoplasms (NENs) may be challenging to diagnose due to their small size and diverse anatomical locations. Hybrid imaging techniques, specifically positron emission tomography/computed tomography (PET/CT) and positron emission tomography/magnetic resonance imaging (PET/MRI), represent the current state-of-the-art for evaluating NENs. The preferred radiopharmaceuticals for NEN PET imaging are gallium-68 (68Ga) DOTA-peptides, which target somatostatin receptors (SSTR) overexpressed on NEN cells. Clinical applications of [68Ga]Ga-DOTA-peptides PET/CT include diagnosis, staging, prognosis assessment, treatment selection, and response evaluation. Fluorodeoxyglucose-18 (18F-FDG) PET/CT aids in detecting low-SSTR-expressing lesions and helps in patient stratification and treatment planning, particularly in grade 3 neuroendocrine tumors (NETs). New radiopharmaceuticals such as fluorine-labeled SSTR agonists and SSTR antagonists are emerging as alternatives to 68Ga-labeled peptides, offering improved detection rates and favorable biodistribution. The maturing of PET/MRI brings advantages to NEN imaging, including simultaneous acquisition of PET and MRI images, superior soft tissue contrast resolution, and motion correction capabilities. The PET/MRI with [68Ga]Ga-DOTA-peptides has demonstrated higher lesion detection rates and more accurate lesion classification compared to PET/CT. Overall, hybrid imaging offers valuable insights in the diagnosis, staging, and treatment planning of NENs. Further research is needed to refine response assessment criteria and standardize reporting guidelines.

Gallium-68 labeled somatostatin receptor antagonist PET/CT in over 500 patients with neuroendocrine neoplasms: experience from a single center in China

PURPOSE

Somatostatin receptor antagonists have shown promising performance for imaging neuroendocrine neoplasms. However, there is a lack of studies exploring the diagnostic performance of SSTR antagonists or comparing them with agonists in a large cohort of patients with NENs. This study aimed to retrospectively review all SSTR antagonist PET/CT scans conducted at Peking Union Medical College Hospital since November 2018 in patients with confirmed or suspected NENs.

METHODS

Four types of SSTR antagonists were utilized, including [68Ga]Ga-NODAGA-LM3, [68Ga]Ga-DOTA-LM3, [68Ga]Ga-NODAGA-JR11, and [68Ga]Ga-DOTA-JR11. The reference standard was based on a combination of histopathology, clinical evaluation, imaging results, and follow-up. Patient-based sensitivity, specificity, and accuracy were evaluated. The SUVmax and tumor-to-liver ratio (TLR) of the hottest lesions was recorded and compared between antagonists and [68Ga]Ga-DOTATATE.

RESULTS

A total of 622 antagonist scans from 549 patients were included in the analysis. The patient-level sensitivity, specificity, and accuracy of antagonist imaging (all tracers combined) were 91.0% (443/487), 91.9% (57/62), and 91.1% (500/549), respectively. In 181 patients with a comparative [68Ga]Ga-DOTATATE PET/CT scan, the patient-level sensitivity, specificity, and accuracy were 87.5% (147/168), 76.9% (10/13), and 86.7% (157/181), respectively. For the hottest lesions, SSTR antagonists all tracers combined demonstrated an overall comparable SUVmax to [68Ga]Ga-DOTATATE (40.1 ± 32.5 vs. 39.4 ± 23.8, p = 0.772). While [68Ga]Ga-NODAGA-LM3 showed significantly higher uptake than [68Ga]Ga-DOTATATE (57.4 ± 38.5 vs. 40.0 ± 22.8, p<0.001), [68Ga]Ga-NODAGA-JR11 (39.7 ± 26.5 vs. 34.3 ± 23.9, p = 0.108) and [68Ga]Ga-DOTA-LM3 (38.9 ± 32.1 vs. 37.2 ± 22.1, p = 0.858) showed comparable uptake to [68Ga]Ga-DOTATATE, and [68Ga]Ga-DOTA-JR11 showed lower uptake (28.9 ± 26.1 vs. 44.0 ± 25.7, p = 0.001). All antagonists exhibited significantly higher TLR than [68Ga]Ga-DOTATATE (12.1 ± 10.8 vs. 5.2 ± 4.5, p<0.001).

CONCLUSION

Gallium-68 labeled SSTR antagonists could serve as alternatives to SSTR agonists for imaging of NENs. Among various antagonists, [68Ga]Ga-NODAGA-LM3 seems to have the best imaging profile.

Gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms (gNENs) display peculiar site-specific features among all NENs. Their incidence and prevalence have been rising in the past few decades. gNENs comprise gastric neuroendocrine carcinomas (gNECs) and gastric neuroendocrine tumours (gNETs), the latter further classified into three types. Type I anatype II gNETs are gastrin-dependent and develop in chronic atrophic gastritis and as part of Zollinger-Ellison syndrome within a multiple endocrine neoplasia type 1 syndrome (MEN1), respectively. Type III or sporadic gNETs develop in the absence of hypergastrinaemia and in the context of a near-normal or inflamed gastric mucosa. gNECs can also develop in the context of variable atrophic, relatively normal or inflamed gastric mucosa. Each gNEN type has different clinical characteristics and requires a different multidisciplinary approach in expert dedicated centres. Type I gNETs are managed mainly by endoscopy or surgery, whereas the treatment of type II gNETs largely depends on the management of the concomitant MEN1. Type III gNETs may require both locoregional approaches and systemic treatments; NECs are often metastatic and therefore require systemic treatment. Specific data regarding the systemic treatment of gNENs are lacking and are derived from the treatment of intestinal NETs and NECs. An enhanced understanding of molecular and clinical pathophysiology is needed to improve the management and outcomes of patients' gNETs.

A Rare Presentation of Extrahepatic Biliary Neuroendocrine Tumor Diagnosed using 68Ga-DOTA-TOC Imaging, But Undetectable on 68Ga-FAPI Imaging

Neuroendocrine tumors (NETs) are commonly seen in the small intestine and rarely found within the bile ducts. This low incidence is due to a smaller number of Kulchitsky cells in the extrahepatic biliary tree, which predisposes to the disease. The diagnosis of biliary tree carcinoid preoperatively is very rare, with most cases in the literature being incidentally diagnosed during surgery or being identified on the histopathology report postoperatively. Here, we present an interesting case of an extrahepatic biliary NET which was diagnosed preoperatively.

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.

Middle Ear Cavity and Mastoid Neuroendocrine Tumor Presenting as Otomastoiditis with Cholesteatoma: A Clinicoradiological and Histopathological Correlation

Neuroendocrine tumors of the middle ear are rare, comprising of less than 2% of primary tumors of the ear. The clinical and imaging findings of these tumors are nonspecific, and histological and immunohistochemical findings are confirmatory. Herein, we present a case of 48-year-old male, presenting with chief complaints of hearing loss of left ear with foul smelling discharge, with the initial clinical impression of otomastoiditis of the middle ear with cholesteatoma and being operated for the same, the final histopathology report inferred it as well-differentiated neuroendocrine tumor grade 1 with Ki-67 index less than 2%. Immunohistochemical examinations demonstrated positive staining of the tumor cells for cytokeratin, synaptophysin and chromogranin A, and negative for smooth muscle actin, desmin, S-100. The biochemical investigations showed raised serum chromogranin A levels. Based upon the findings on anatomical imaging modalities including high-resolution computed tomography temporal bone and magnetic resonance imaging paranasal sinuses (MRI PNS), the lesion was inferred inoperable due to involvement of dura of petrous apex, and therefore he was referred for consideration of peptide receptor radionuclide therapy (PRRT). MRI PNS also showed involvement of the horizontal part of facial nerve, indicating local aggressiveness of the tumor. 68 Ga-DOTATATE-PET/CT showed high-grade somatostatin receptor expressing soft tissue lesion involving middle ear and external auditory canal (Krenning's score 4), with low-grade metabolic activity on 18 F-FDG-PET/CT. The post-therapy scan following 177 Lu-DOTATATE PRRT, showed abnormal tracer concentration at the described site. Due to extreme rarity of this disease entity, it is important to accrue data for accurate diagnosis, proper management, and follow-up.

[Infectious pneumonia favored by paraneoplastic Cushing syndrome in a pulmonary carcinoid tumor]

INTRODUCTION

Ectopic Cushing's syndrome (CS) is a rare condition nevertheless well-known to endocrinologists. The pneumologist may be called upon to treat CS not only because bronchial carcinoid tumors are the most frequent source of ectopic ACTH secretion, but also due to the fact that the immunosuppression induced by hypercorticism favors lower respiratory tract infections.

CASE REPORT

We report the case of a female patient presenting with acute respiratory failure secondary to Enterobacter cloacae pneumonia exacerbated by SC. Further investigations confirmed ectopic ACTH secretion and revealed a right upper lobe pulmonary nodule. After appropriate antibiotic therapy, the patient received preoperative adrenolytic treatment. Management by right upper lobectomy resulted in the extraction of a 12mm tumor. Pathological analysis was consistent with the diagnosis of a typical carcinoid tumor. Immunohistochemistry confirmed ACTH secretion by the tumor. Even though the postoperative course showed CS regression, the patient developed adrenal insufficiency.

CONCLUSION

Ectopic CS induces immunosuppression, which aggravates lower respiratory tract infections. Search for a pulmonary neuroendocrine tumor should be systematic. Following control of the secretory syndrome by adrenolytic treatment, and if the diagnosis of carcinoid tumor is confirmed, surgical treatment is the preferred option.

Diagnostic accuracy of SSR-PET/CT compared to histopathology in the identification of liver metastases from well-differentiated neuroendocrine tumors

BACKGROUND

Histopathology is the reference standard for diagnosing liver metastases of neuroendocrine tumors (NETs). Somatostatin receptor-positron emission tomography / computed tomography (SSR-PET/CT) has emerged as a promising non-invasive imaging modality for staging NETs. We aimed to assess the diagnostic accuracy of SSR-PET/CT in the identification of liver metastases in patients with proven NETs compared to histopathology.

METHODS

Histopathologic reports of 139 resected or biopsied liver lesions of patients with known NET were correlated with matching SSR-PET/CTs and the positive/negative predictive value (PPV/NPV), sensitivity, specificity, and diagnostic accuracy of SSR-PET/CT were evaluated. PET/CT reading was performed by one expert reader blinded to histopathology and clinical data.

RESULTS

133 of 139 (95.7%) liver lesions showed malignant SSR-uptake in PET/CT while initial histopathology reported on 'liver metastases of NET´ in 127 (91.4%) cases, giving a PPV of 91.0%. Re-biopsy of the initially histopathologically negative lesions (reference standard) nevertheless diagnosed 'liver metastases of NET' in 6 cases, improving the PPV of PET/CT to 95.5%. Reasons for initial false-negative histopathology were inadequate sampling in the sense of non-target biopsies. The 6 (4.3%) SSR-negative lesions were all G2 NETs with a Ki-67 between 2-15%.

CONCLUSION

SSR-PET/CT is a highly accurate imaging modality for the diagnosis of liver metastases in patients with proven NETs. However, we found that due to the well-known tumor heterogeneity of NETs, specifically in G2 NETs approximately 4-5% are SSR-negative and may require additional imaging with [18F]FDG PET/CT.

Typical Zollinger-Ellison syndrome-atypical location of gastrinoma and absence of hypergastrinemia: A case report and review of literature

BACKGROUND

Zollinger-Ellison syndrome (ZES) results from hypersecretion of gastrin from pancreatic or duodenal neuroendocrine tumors, commonly referred to as gastrinomas. The high levels of gastrin lead to a typical presentation involving watery diarrhea and multiple ulcers in the duodenum. Here, we have presented the rare case of a patient with ZES and absence of hypergastrinemia as well as an atypical location of gastrinoma.

CASE SUMMARY

A 72-year-old woman presented with the typical clinical manifestations of ZES, including upper abdominal pain, significant watery diarrhea, and acidic liquid vomitus. Surprisingly, however, she did not have an increased level of serum gastrin. In addition, there was no evidence of gastrinoma or any other ulcerogenic tumor. Esophagogastroduodenoscopy was conducted to examine the upper digestive tract. Revised diagnoses were considered, and an individualized treatment plan was developed. The patient responded to antacid medication while experiencing intermittent, recurring bouts of ZES. 18F-AlF-NOTA-octreotide positron emission tomography (18F-OC PET)/computed tomography (CT) helped locate the tumor. Postoperative pathology and immunohistochemistry results suggested that the tumor was a gastrinoma located at an unconventional site.

CONCLUSION

This present case study demonstrates the possibility of ZES-like manifestation in patients with absence of hypergastrinemia. 18F-OC PET/CT is a relatively new imaging technique that can be applied for diagnosing even tiny gastrinomas that are atypical in terms of location.

Mesenteric Paraganglioma: A Case Report and Literature Review

We report a rare case of a solitary paraganglioma arising from the small bowel mesentery, found in a 70-year-old female who presented with abdominal pain. Paragangliomas are rare neuroendocrine, neural crest-derived tumors, most commonly found in the adrenal medulla. While extra-adrenal paragangliomas arise from diverse locations, mesenteric origins are extremely rare. Our comprehensive review shows 35 previously documented cases and updates the epidemiology, clinical features, and outcomes of mesenteric paragangliomas.

Imaging of Small-Bowel Neuroendocrine Neoplasms: AJR Expert Panel Narrative Review

Neuroendocrine neoplasms (NENs) of the small bowel are typically slow-growing lesions that remain asymptomatic until reaching an advanced stage. Imaging modalities for lesion detection, staging, and follow-up in patients with known or suspected NEN include CT enterography, MR enterography, and PET/CT using a somatostatin receptor analog. FDG PET/CT may have a role in the evaluation of poorly differentiated NENs. Liver MRI, ideally with a hepatocyte-specific contrast agent, should be used in the evaluation of hepatic metastases. Imaging informs decisions regarding both surgical approaches and systematic therapy (specifically, peptide receptor radionuclide therapy). This AJR Expert Panel Narrative Review describes the multimodality imaging features of small-bowel NENs; explores the optimal imaging modalities for their diagnosis, staging, and follow-up; and discusses how imaging may be used to guide therapy.

Preclinical and pilot clinical evaluation of a small-molecule carbonic anhydrase IX targeting PET tracer in clear cell renal cell carcinoma

PURPOSE

Clear cell renal cell carcinoma (ccRCC) highly expresses carbonic anhydrase IX (CAIX). The purpose of this study was to evaluate 68Ga-NY104, a small-molecule CAIX-targeting PET agent, in tumor models of ccRCC and patients diagnosed with confirmed, or suspicious, ccRCC.

METHODS

The in vivo and ex vivo biodistribution of 68Ga-NY104 was investigated in CAIX-positive OS-RC-2 xenograft-bearing models. The binding of the tracer was further validated using autoradiography for human ccRCC samples. In addition, three patients with confirmed or suspicious ccRCC were studied.

RESULTS

NY104 can be labeled with high radiochemical yield and purity. It quickly cleared through kidney with α-half-life of 0.15 h. Discernible uptake is noted in the heart, lung, liver, stomach, and kidney. The OS-RC-2 xenograft demonstrated intense uptake 5 min after injection and gradually increased until 3 h after injection with ID%/g of 29.29 ± 6.82. Significant binding was detected using autoradiography on sections of human ccRCC tumor. In the three patients studied, 68Ga-NY104 was well-tolerated and no adverse events were reported. Substantial accumulation was observed in both primary and metastatic lesions in patient 1 and 2 with SUVmax of 42.3. Uptake in the stomach, pancreas, intestine, and choroid plexus was noted. The lesion in third patient was correctly diagnosed as non-metastatic for negative 68Ga-NY104 uptake.

CONCLUSION

68Ga-NY104 can efficiently and specifically bind to CAIX. Given the pilot nature of our study, future clinical studies are warranted to evaluate 68Ga-NY104 for detection of CAIX-positive lesions in patients with ccRCC.

TRIAL REGISTRATION

The clinical evaluation part of this study was retrospectively registered at ClinicalTrial.gov (NCT05728515) as NYPILOT on 6 Feb, 2023.

PET/CT Imaging in Treatment Planning and Surveillance of Sinonasal Neoplasms

Sinonasal cancers are uncommon malignancies with a generally unfavorable prognosis, often presenting at an advanced stage. Their high rate of recurrence supports close imaging surveillance and the utilization of functional imaging techniques. Whole-body 18F-FDG PET/CT has very high sensitivity for the diagnosis of sinonasal malignancies and can also be used as a "metabolic biopsy" in the characterization of some of the more common subgroups of these tumors, though due to overlap in uptake, histological confirmation is still needed. For certain tumor types, radiotracers, such as 11C-choline, and radiolabeled somatostatin analogs, including 68Ga-DOTATATE/DOTATOC, have proven useful in treatment planning and surveillance. Although serial scans for posttreatment surveillance allow the detection of subclinical lesions, the optimal schedule and efficacy in terms of survival are yet to be determined. Pitfalls of 18F-FDG, such as post-surgical and post-radiotherapy crusting and inflammation, may cause false-positive hypermetabolism in the absence of relapse.

Prognostic Implications of PET-Derived Tumor Volume and Uptake in Patients with Neuroendocrine Tumors

Historically, molecular imaging of somatostatin receptor (SSTR) expression in patients with neuroendocrine tumors (NET) was performed using SSTR scintigraphy (SRS). Sustained advances in medical imaging have led to its gradual replacement with SSTR positron-emission tomography (SSTR-PET). The higher sensitivity in comparison to SRS on the one hand and conventional cross-sectional imaging, on the other hand, enables more accurate staging and allows for image quantification. In addition, in recent years, a growing body of evidence has assessed the prognostic implications of SSTR-PET-derived prognostic biomarkers for NET patients, with the aim of risk stratification, outcome prognostication, and prediction of response to peptide receptor radionuclide therapy. In this narrative review, we give an overview of studies examining the prognostic value of advanced SSTR-PET-derived (semi-)quantitative metrics like tumor volume, uptake, and composite metrics. Complementing this analysis, a discussion of the current trends, clinical implications, and future directions is provided.

Increased Vertebral Gallium-68-DOTATATE Activity on Positron Emission Tomography-Computed Tomography in Merkel Cell Carcinoma: Not Always Metastasis

Merkel cell carcinoma (MCC) is a rare neuroendocrine dermal malignancy seen in elderly light-skinned individuals, associated with immunosuppression and Merkel cell polyomavirus infection. As a neuroendocrine tumor, the recurrence and metastasis of MCC can be evaluated using positron emission tomography-computed tomography (PET-CT) with the Gallium-68-DOTATATE (Ga-68-DOTATATE) radiotracer, which has demonstrated increased sensitivity to neuroendocrine metastases when compared to F-18 fluorodeoxyglucose (FDG). Here, we present the case of a patient with known metastatic MCC with a new, abnormal focus of increased radiotracer activity in the thoracic spine on Ga-68-DOTATATE PET-CT suspected to represent a metastatic lesion. Further evaluation with MRI revealed a benign vertebral hemangioma, highlighting the limitations of this radiotracer in the setting of benign spinal lesions. Multimodality imaging findings of metastatic MCC and potential pitfalls of Ga-68-DOTATATE PET-CT staging are discussed.

Gastroenteropancreatic Neuroendocrine Tumor Diagnosis: DOTATATE PET/CT

Gastroenteropancreatic neuroendocrine tumors(NETs), which arise from the small intestine, rectum, colon, appendix, or pancreas, have variable malignant potential with clinical behavior determined by proliferative activity according to the Ki-67 index and tumor differentiation. Somatostatin receptor (SSTR) expression by NETs allows SSTR imaging using 68Ga-DOTATATE PET/computed tomography (CT) and treatment with octreotide or SSTR-targeted peptide receptor radionuclide therapy (PRRT). 68Ga-DOTATATE PET/CT is indicated for localization of the primary tumor in select cases, staging patients with known NET, and selecting patients for PRRT. NCCN guidelines consider imaging with 68Ga-DOTATATE PET/CT appropriate for staging and receptor status assessment.

Integrating Functional Imaging and Molecular Profiling for Optimal Treatment Selection in Neuroendocrine Neoplasms (NEN)

PURPOSE OF REVIEW

Gastroenteropancreatic NEN (GEP-NEN) are group of malignancies with significant clinical, anatomical and molecular heterogeneity. High-grade GEP-NEN in particular present unique management challenges.

RECENT FINDINGS

In the current era, multidisciplinary management with access to a combination of functional imaging and targeted molecular profiling can provide important disease characterisation, guide individualised management and improve patient outcome. Multiple treatment options are now available, and combination and novel therapies are being explored in clinical trials. Precision medicine is highly relevant for a heterogenous disease like NEN. The integration of dual-tracer functional PET/CT imaging, molecular histopathology and genomic data has the potential to be used to gain a more comprehensive understanding of an individual patient's disease biology for precision diagnosis, prognostication and optimal treatment allocation.

Prospective Multicentric Assessment of 68Ga-DOTANOC PET/CT in Grade 1-2 GEP-NET

The aim of this multicentric study was to prospectively compare 68Ga-DOTANOC PET/CT versus somatostatin receptor scintigraphy (SRS) with SPECT/CT, combined with multiphasic CT scan and MRI in patients with grade 1 or 2 gastroenteropancreatic neuroendocrine tumors (GEP-NET). Patients with histologically proven grade 1 or 2 GEP-NET with suspicion of recurrence or progression, or with typical aspects of GEP-NET on morphological imaging, were explored with conventional imaging (CI): SRS with SPECT/CT, multiphasic CT scan and/or liver MRI followed by 68Ga-DOTANOC PET/CT. The gold standard was based on histology and imaging follow-up. The data of 105 patients (45 woman and 60 men; median age) were analyzed. 68Ga-DOTANOC PET/CT sensitivity was significantly higher than CI sensitivity in per-patient (98.9% vs. 88.6%, p = 0.016) and per-region (97.6% vs. 75.6%, p < 0.001) analyses, in the detection of the primary (97.9% vs. 78.7%; p = 0.016), peritoneal carcinomatosis (95% vs. 30%, p < 0.001), and bone metastases (100% vs. 33.3%, p = 0.041). 68Ga-DOTANOC PET/CT had an impact on the therapeutic management of 41.9% (44/105) patients compared to decisions based on CI explorations. Our data confirm the superiority of 68Ga-DOTANOC PET/CT over CI in the detection of peritoneal carcinomatosis and bone metastasis, as well as its strong therapeutic impact on the management of patients with grade 1-2 GEP-NETs.

Rectal neuroendocrine neoplasms: what the radiologists should know

Neuroendocrine neoplasms of the rectum (R-NENs) are rare; however, their incidence has increased almost threefold in the last few decades. Imaging of R-NENs includes two primary categories: anatomic/morphologic imaging comprised of endoscopic ultrasound (EUS), computed tomography (CT), magnetic resonance imaging (MRI), and functional/molecular imaging comprising of planar scintigraphy, single-photon emission computed tomography (SPECT), and positron emission tomography (PET). The management depends on stage, dimension, atypical features, histological grade, and lymphovascular invasion (LVI). Low-risk local R-NENs can be resected endoscopically, and high-risk or locally advanced neoplasms can be treated with radical surgery and lymphadenectomy and/or chemoradiation. The review article focuses on imaging illustrations and discusses applications of different imaging modalities in diagnosing and managing R-NENs.

NETest: serial liquid biopsies in gastroenteropancreatic NET surveillance

Objective

Up to now, serial NETest measurements in individuals assessing the disease course of gastroenteropancreatic neuroendocrine tumors (GEPNETs) at long-term follow-up and treatment response were not studied.

Design

The study was a longitudinal validation study of serial NETest measurements - a blood-based gene expression signature - in 132 patients with GEPNETs on therapy or watch-and-wait strategy.

Methods

Serial samples were collected during 46 (range: 6-71) months of follow-up. NETest scores were compared with Response Evaluation Criteria in Solid Tumors version 1.1-defined treatment response (e.g. no evidence of disease (NED), stable disease (SD) or progressive disease (PD)).

Results

Consecutive NETest scores fluctuated substantially (range: 0-100) over time in individuals with SD (n = 28) and NED (n = 30). Follow-up samples were significantly higher in SD (samples 3-5) and NED subgroups (samples 2-5) compared with baseline results, without changes in imaging. In 82% of untreated patients with PD, consecutive NETest scores consistently remained high. In patients undergoing systemic treatment, the median pre-treatment NETest score in treatment-responders was 76.5 (n = 22) vs 33 (n = 12) in non-responders (P = 0.001). Patients with low pre-treatment scores had 21 months reduced progression-free survival (10 vs 31 months; P = 0.01). The accuracy of the NETest for treatment response prediction was 0.73 (P = 0.009).

Conclusion

In patients not undergoing treatment, consecutive low NETest scores are associated with indolent behavior. Patients who develop PD exhibit elevated scores. Elevated results have important predictive value for treatment responsiveness and could be used for individualizing decisions on systemic therapy. The clinical value of follow-up NETest scores for patients who choose to watch and wait requires further study.

The Role of 68 Ga-DOTA-SSA PET/CT in the Management and Prediction of Peptide Receptor Radionuclide Therapy Response for Patients With Neuroendocrine Tumors : A Systematic Review and Meta-analysis

PURPOSE

The aim of this study was to identify and evaluate the role of 68 Ga-DOTA-somatostatin analog (SSA) PET/CT in guiding treatment for patients with neuroendocrine tumors (NETs) based on published literature, with specific focus on the ability of PET/CT to impact clinical management and predict peptide receptor radionuclide therapy (PRRT) response.

PATIENTS AND METHODS

A systematic literature search of articles up to December 2021 was performed using PubMed and Scopus. Eligible studies included ≥10 patients with confirmed or suspected NETs who had undergone pretreatment staging 68 Ga-DOTA-SSA PET/CT. A meta-analysis using the random-effects model was conducted to determine the overall change in management after PET/CT, whereas PET/CT-derived parameters that correlated with PRRT outcome were summarized from studies that assessed its predictive capabilities.

RESULTS

A total of 39 studies were included in this systemic review, of which 2266 patients from 24 studies were included for meta-analysis. We showed that PET/CT resulted in a change in clinical management in 36% (95% confidence interval, 31%-41%; range, 3%-66%) of patients. Fifteen studies consisting of 618 patients examined the prognostic ability of 68 Ga-DOTA-SSA PET/CT for PRRT. Of those, 8 studies identified a higher pretreatment SUV to favor PRRT, and 4 identified PET-based radiomic features for somatostatin receptor heterogeneity to be predictive of PRRT response.

CONCLUSIONS

Along with its diagnostic abilities, 68 Ga-DOTA-SSA PET/CT can impact treatment decision-making and may predict PRRT response in patients with NETs. More robust studies should be conducted to better elucidate the prognostic role of somatostatin receptor PET/CT in optimizing treatment for clinical outcome.

Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are the most common type of neuroendocrine tumors and are being increasingly identified in clinical practice. The diagnosis, staging, management, and surveillance of GEP-NETs rely heavily on endoscopy, and consequently, it is important for gastroenterologists to have a solid understanding of these tumors. This article reviews the presentation, diagnosis, and management of both localized and advanced GEP-NETs, with increased emphasis on the role of endoscopy, to enable gastroenterologists and other practitioners to have the necessary tools for the care of patients with these tumors.

Systemic Therapy of Advanced Well-differentiated Small Bowel Neuroendocrine Tumors Progressive on Somatostatin Analogues

OPINION STATEMENT

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors whose management requires a nuanced and multi-disciplinary approach in order to control symptoms, halt tumor growth, and improve survival outcomes. Of late, the treatment landscape of NENs has advanced considerably as a result of several pivotal clinical trials, which have established somatostatin analogues as first-line therapy for advanced, metastatic, well-differentiated neuroendocrine tumors (NETs). However, an evolving classification system as well as an increased understanding of distinct clinical, molecular, and biologic features contribute to complexity in management. In particular, there remains limited randomized prospective data in the somatostatin analogue (SSA)-refractory setting for patients with primary tumors that originate in the small bowel. For well-differentiated small bowel neuroendocrine tumors (SBNETs), treatment beyond SSAs includes radionuclide therapy, targeted agents, liver-directed therapy, and to a lesser extent, cytotoxic chemotherapy. In the current era, selection of these agents is largely based on expert opinion in the context of patient and tumor characteristics without definitive data on the preferred order of agents to administer. In this review, we aim to describe the treatment landscape of metastatic SBNETs beyond SSAs and provide an overview of novel treatments which are currently under clinical evaluation.

Integration of molecular imaging in the personalized approach to neuroendocrine tumors

NETs lesions can be difficult to characterize with conventional anatomic imaging (CT and MRI). Functional imaging techniques, and especially PET imaging, are very useful for detecting small neuroendocrine tumors that would not be seen with other techniques. The role of nuclear medicine in the localization, staging, restaging, treatment and monitoring of neuroendocrine tumors (NETs) has become progressively more relevant due to: the availability of tracers on new targets, tracers for positron emission tomography (PET); the development of cyclotrons and generators that allow this availability; as well as to hybrid systems (SPECT/CT, PET/CT and PET/MRI) that, by joining the functional and anatomical image, improve the quality of the images. Teragnosis, a new emerging therapy, in NET used receptor-mediated or nonreceptor- mediated mechanism to facilitate penetration and high-affinity binding between the radiopharmaceutical and the tumor cell. Teragnosis offers the possibility of personalized targeted radionuclide therapy.

Role of [18F]FDG PET/CT in the management of G1 gastro-entero-pancreatic neuroendocrine tumors

PURPOSE

Since the role of [¹⁸F]FDG PET/CT in low-grade gastroenteropancreatic (GEP) neuroendocrine neoplasia (NET) is not well established, this study was aimed to evaluate the role of [¹⁸F]FDG PET/CT in grade 1 (G1) GEP-NETs.

METHODS

This is a retrospective study including patients with G1 GEP-NETs who underwent [¹⁸F]FDG PET/CT.

RESULTS

55 patients were evaluated, including 24 (43.6%) with pancreatic NETs and 31 (56.4%) with gastrointestinal NETs. At the time of diagnosis, 28 (51%) patients had metastatic disease, and 50 (91%) patients were positive by 68-Ga sstr PET/CT. Overall, 27 patients (49%) had positive findings on [¹⁸F]FDG PET/CT. Following [¹⁸F]FDG PET/CT, therapeutic management was modified in 29 (52.7%) patients. Progression-free survival was longer in patients with negative [¹⁸F]FDG PET/CT compared with positive [¹⁸F]FDG PET/CT (median PFS was not reached and 24 months, respectively, p = 0.04). This significance was particularly evident in the pancreatic group (p = 0.008).

CONCLUSIONS

Despite having low proliferative activity, approximately half of GEP-NETs G1 showed positive [¹⁸F]FDG PET/CT, with a corresponding negative impact on patients' clinical outcomes. These data are in favor of a more "open" attitude toward the potential use of [¹⁸F]FDG PET/CT in the diagnostic work-up of G1 GEP-NETs, which may be used in selected cases to detect those at higher risk for an unfavorable disease course.

Shining Damaged Hearts: Immunotherapy-Related Cardiotoxicity in the Spotlight of Nuclear Cardiology

The emerging use of immunotherapies in cancer treatment increases the risk of immunotherapy-related cardiotoxicity. In contrast to conventional chemotherapy, these novel therapies have expanded the forms and presentations of cardiovascular damage to a broad spectrum from asymptomatic changes to fulminant short- and long-term complications in terms of cardiomyopathy, arrythmia, and vascular disease. In cancer patients and, particularly, cancer patients undergoing (immune-)therapy, cardio-oncological monitoring is a complex interplay between pretherapeutic risk assessment, identification of impending cardiotoxicity, and post-therapeutic surveillance. For these purposes, the cardio-oncologist can revert to a broad spectrum of nuclear cardiological diagnostic workup. The most promising commonly used nuclear medicine imaging techniques in relation to immunotherapy will be discussed in this review article with a special focus on the continuous development of highly specific molecular markers and steadily improving methods of image generation. The review closes with an outlook on possible new developments of molecular imaging and advanced image evaluation techniques in this exciting and increasingly growing field of immunotherapy-related cardiotoxicity.

Radiolabeled Somatostatin Analogues for Diagnosis and Treatment of Neuroendocrine Tumors

Simple Summary

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors, presenting in often challenging clinical scenarios, and require multidisciplinary discussion for optimal care. The theranostic approach (DOTA peptides labelled with ⁶⁸Ga for imaging well-differentiated neuroendocrine tumors NETs, and labelled with ⁹⁰Y or ¹⁷⁷Lu for therapy) plays a crucial role in the management of NENs to assess disease extension and criteria for peptide receptor radionuclide therapy (PRRT) eligibility of based on somatostatin receptor (SSTR) expression. The present paper is an overview of currently employed radiolabeled SSTR analogues used for both diagnosis and therapy of NENs. Further emerging radiopharmaceuticals targeting SSTRs (e.g., fluorinated SSTR agonists, radiolabeled SSTR antagonists) as well as strategies to improve PRRT efficacy (by means of implementation of personalized treatment schemes, dosimetry, amelioration of response assessment strategies, and optimization of treatment sequencing) are also discussed. Finally, although very preliminary, some studies employing radiomic features in various kinds of NET are reported.

Abstract

Neuroendocrine neoplasms (NENs) are rare and heterogeneous tumors that require multidisciplinary discussion for optimal care. The theranostic approach (DOTA peptides labelled with ⁶⁸Ga for diagnosis and with ⁹⁰Y or ¹⁷⁷Lu for therapy) plays a crucial role in the management of NENs to assess disease extension and as a criteria for peptide receptor radionuclide therapy (PRRT) eligibility based on somatostatin receptor (SSTR) expression. On the diagnostic side, [⁶⁸Ga]Ga-DOTA peptides PET/CT (SSTR PET/CT) is the gold standard for imaging well-differentiated SSTR-expressing neuroendocrine tumors (NETs). [¹⁸F]FDG PET/CT is useful in higher grade NENs (NET G2 with Ki-67 > 10% and NET G3; NEC) for more accurate disease characterization and prognostication. Promising emerging radiopharmaceuticals include somatostatin analogues labelled with ¹⁸F (to overcome the limits imposed by ⁶⁸Ga), and SSTR antagonists (for both diagnosis and therapy). On the therapeutic side, the evidence gathered over the past two decades indicates that PRRT is to be considered as an effective and safe treatment option for SSTR-expressing NETs, and is currently included in the therapeutic algorithms of the main scientific societies. The positioning of PRRT in the treatment sequence, as well as treatment personalization (e.g., tailored dosimetry, re-treatment, selection criteria, and combination with other alternative treatment options), is warranted in order to improve its efficacy while reducing toxicity. Although very preliminary (being mostly hampered by lack of methodological standardization, especially regarding feature selection/extraction) and often including small patient cohorts, radiomic studies in NETs are also presented. To date, the implementation of radiomics in clinical practice is still unclear. The purpose of this review is to offer an overview of radiolabeled SSTR analogues for theranostic use in NENs.

The "Ultimate Triple PET": 68Ga-DOTATATE, 18F-FDG, and 18F-Fluciclovine PET/CT Findings in a Single Patient With Metastatic Abdominal Carcinoid and Prostate Cancer

ABSTRACT

A 71-year-old man with a history of carcinoid and prostate adenocarcinoma underwent 68Ga-DOTATATE PET/CT to evaluate new mediastinal lymphadenopathy. The scan revealed new carcinoid metastases, but the mediastinal nodes were not avid. 18F-FDG PET/CT was performed to evaluate for cardiac and mediastinal sarcoidosis, revealing a lack of cardiac sarcoidosis, but probable mediastinal sarcoidosis. 18F-Fluciclovine PET/CT was then performed for possible prostate metastases, revealing the patient's known prostate cancer. Three different PET radiopharmaceuticals revealed 3 different processes in a single patient within a 195-day period, demonstrating the power of nuclear medicine diagnostics.

68Ga-DOTATATE PET/CT versus 111In-octreotide scintigraphy in patients with neuroendocrine tumors: a prospective study

Objective

To compare ⁶⁸Ga-DOTA-DPhe1,Tyr3-octreotate (⁶⁸Ga-DOTATATE) positron-emission tomography/computed tomography (PET/CT) findings with those of conventional ¹¹¹In-octreotide scintigraphy in patients with neuroendocrine tumors (NETs).

Materials and Methods

This was a single-center prospective study including 41 patients (25 males; mean age, 55.4 years) with biopsy-proven NETs who underwent whole-body ¹¹¹In-octreotide scintigraphy and whole-body ⁶⁸Ga-DOTATATE PET/CT. The patients had been referred for tumor staging (34.1%), tumor restaging (61.0%), or response evaluation (4.9%). Images were compared in a patient-by-patient analysis to identify additional lesions, and we attempted to determine the impact that discordant findings had on treatment planning.

Results

Compared with ¹¹¹In-octreotide scintigraphy, ⁶⁸Ga-DOTATATE PET/CT revealed more lesions, the additional lesions typically being in the liver or bowel. Changes in management owing to the additional information provided by ⁶⁸Ga-DOTATATE PET/CT occurred in five patients (12.2%), including intermodal changes in three (7.3%) and intramodal changes in two (4.9%). In addition, ⁶⁸Ga-DOTATATE PET/CT yielded incidental findings unrelated to the primary NET in three patients (7.3%): Hürthle cell carcinoma of the thyroid, bowel non-Hodgkin lymphoma, and a suspicious breast lesion.

Conclusion

We conclude that ⁶⁸Ga-DOTATATE PET/CT is superior to conventional ¹¹¹In-octreotide scintigraphy for the management of NETs because of its ability to determine the extent of the disease more accurately, which, in some cases, translates to changes in the treatment plan.

Gastrinoma and Zollinger Ellison syndrome: A roadmap for the management between new and old therapies

Zollinger-Ellison syndrome (ZES) associated with pancreatic or duodenal gastrinoma is characterized by gastric acid hypersecretion, which typically leads to gastroesophageal reflux disease, recurrent peptic ulcers, and chronic diarrhea. As symptoms of ZES are nonspecific and overlap with other gastrointestinal disorders, the diagnosis is often delayed with an average time between the onset of symptoms and final diagnosis longer than 5 years. The critical step for the diagnosis of ZES is represented by the initial clinical suspicion. Hypergastrinemia is the hallmark of ZES; however, hypergastrinemia might recognize several causes, which should be ruled out in order to make a final diagnosis. Gastrin levels > 1000 pg/mL and a gastric pH below 2 are considered to be diagnostic for gastrinoma; some specific tests, including esophageal pH-recording and secretin test, might be useful in selected cases, although they are not widely available. Endoscopic ultrasound is very useful for the diagnosis and the local staging of the primary tumor in patients with ZES, particularly in the setting of multiple endocrine neoplasia type 1. Some controversies about the management of these tumors also exist. For the localized stage, the combination of proton pump inhibitory therapy, which usually resolves symptoms, and surgery, whenever feasible, with curative intent represents the hallmark of gastrinoma treatment. The high expression of somatostatin receptors in gastrinomas makes them highly responsive to somatostatin analogs, supporting their use as anti-proliferative agents in patients not amenable to surgical cure. Other medical options for advanced disease are super-imposable to other neuroendocrine neoplasms, and studies specifically focused on gastrinomas only are scant and often limited to case reports or small retrospective series. The multidisciplinary approach remains the cornerstone for the proper management of this composite disease. Herein, we reviewed available literature about gastrinoma-associated ZES with a specific focus on differential diagnosis, providing potential diagnostic and therapeutic algorithms.

Imaging of neuroendocrine tumors: A pictorial review of the clinical value of different imaging modalities

Neuroendocrine tumors (NETs) are multifaceted tumors occurring in a variety of organs and often present as metastatic at the time of diagnosis. Accurate staging is the most significant factor in therapy planning, but it remains a challenge. Imaging is established as the cornerstone for disease detection/diagnosis, staging, and follow up. To accurately assess and monitor tumor burden in patients with NETs, various imaging techniques have been developed and optimized. Current recommendations for the imaging of patients with NETs include a combination of both morphologic (or anatomic) and molecular imaging, but a final choice can be puzzling for clinicians. Recognizing that there is no uniform sequence consensus on the "best" imaging test, and the heterogeneity of technologic availability at different centers, we hope to provide a pictorial review of the different imaging techniques and their role and utility in management of patients with NETs, aimed to provide a practical guide for all clinicians.

Variants and Pitfalls in PET/CT Imaging of Gastrointestinal Cancers

In the past two decades, PET/CT has become an essential modality in oncology increasingly used in the management of gastrointestinal (GI) cancers. Most PET/CT tracers used in clinical practice show some degree of GI uptake. This uptake is quite variable and knowledge of common patterns of biodistribution of various radiotracers is helpful in clinical practice. 18F-Fluoro-Deoxy-Glucose (FDG) is the most commonly used radiotracer and has quite a variable uptake within the bowel. 68Ga-Prostate specific membrane antigen (PSMA) shows intense uptake within the proximal small bowel loops. 11C-methyl-L-methionine (MET) shows high accumulation within the bowels, which makes it difficult to assess bowel or pelvic diseases. One must also be aware of technical artifacts causing difficulties in interpretations, such as high attenuation oral contrast material within the bowel lumen or misregistration artifact due to patient movements. It is imperative to know the common variants and benign diseases that can mimic malignant pathologies. Intense FDG uptake within the esophagus and stomach may be a normal variant or may be associated with benign conditions such as esophagitis, reflux disease, or gastritis. Metformin can cause diffuse intense uptake throughout the bowel loops. Intense physiologic uptake can also be seen within the anal canal. Segmental bowel uptake can be seen in inflammatory bowel disease, radiation, or medication induced enteritis/colitis or infection. Diagnosis of appendicitis or diverticular disease requires CT correlation, as normal appendix or diverticulum can show intense uptake. Certain malignant pathologies are known to have only low FDG uptake, such as early-stage esophageal adenocarcinoma, mucinous tumors, indolent lymphomas, and multicystic mesotheliomas. Response assessment, particularly in the neoadjuvant setting, can be limited by post-treatment inflammatory changes. Post-operative complications such as abscess or fistula formation can also show intense uptake and may obscure underlying malignant pathology. In the absence of clinical suspicion or rising tumor marker, the role of FDG PET/CT in routine surveillance of patients with GI malignancy is not clear.

Middle ear neuroendocrine tumours: Insight into their pathogenesis, diagnosis and management

Recent advances in the diagnosis of neuroendocrine tumours (NETs) have led to the identification of NETs in unusual locations. NETs originating in the middle ear have been reported in a number of case reports with differing terminologies, where they were variously referred to as middle ear adenomas or middle ear carcinoids. In this report, we describe two cases of middle ear NETs with locally advanced disease and with distant metastases, respectively. The embryological origin, pathogenesis and histopathological characteristics, including immunohistochemical markers, are discussed aiming to clarify the terminology of these tumours. Functional imaging modalities (eg, 68 Ga-DOTATATE positron emission tomography/computed tomography/magnetic resonance imaging) play a pivotal role in the diagnosis, staging and determining the optimal systemic therapy in managing NETs of the middle ear. In addition, surgical, local and systemic therapeutic modalities are discussed, including the management option of long-acting somatostatin analogue therapy and targeted radionuclide therapy for somatostatin receptor-positive well-differentiated middle ear NETs.

Ga-68 DOTATATE PET/CT and F-18 FDG PET/CT in the evaluation of low and intermediate versus high-grade neuroendocrine tumors

OBJECTIVE

We investigated the role of Ga-68 DOTATATE PET/CT in comparison to F-18 FDG PET/CT in patients with low and intermediate versus high-grade neuroendocrine tumors (NETs).

METHODS

We identified 81 patients who underwent Ga-68 DOTATATE PET/CT at our institution between May 2017 and December 2018 and met inclusion criteria of biopsy-proven NET with known Ki-67 index, histologic grade, or differentiation. Patients were divided into two groups. Control group included Ki-67 ≤20%, grade 1 or 2, or well-differentiated tumors. Experimental group included Ki-67 >20%, grade 3, or poorly-differentiated tumors.

RESULTS

Mean age was 57 years, with 36 males and 45 females. Most common primary sites were small bowel, pancreas, and lung. Most common distant metastatic sites were liver and bone. In the control group (n = 67), median Ki-67 was 4% (range 1-30%). 55/67 (82.1%) DOTATATE and 6/11 (54.5%) FDG scans were positive (P = 0.04). Positive scans showed >10 lesions in 25/55 (45.5%) DOTATATE and 1/6 (16.7%) FDG scans (P = 0.18). 40/55 (72.7%) positive DOTATATE and 3/6 (50%) FDG scans showed distant disease (P = 0.25). In the experimental group (n = 14), median Ki-67 was 68% (range 25-95%). All 14 DOTATATE and all nine FDG scans were positive. Positive scans showed >10 lesions in 4/14 (28.6%) DOTATATE and 5/9 (55.6%) FDG scans (P = 0.20). 10/14 (71.4%) positive DOTATATE and 7/9 (77.8%) FDG scans showed distant disease (P = 0.74).

CONCLUSION

All patients with high grade, poorly-differentiated NETs had positive DOTATATE PET/CTs. In these patients, DOTATATE PET/CT did not significantly differ from FDG PET/CT in identifying >10 lesions or distant disease.

Imaging and its Impact on Defining the Oligometastatic State

Successful treatment of oligometastatic disease (OMD) is facilitated through timely detection and localization of disease, both at the time of initial diagnosis (synchronous OMD) and following the initial therapy (metachronous OMD). Hence, imaging plays an indispensable role in management of patients with OMD. However, the challenges and complexities of OMD management are also reflected in the imaging of this entity. While innovations and advances in imaging technology have made a tremendous impact in disease detection and management, there remain substantial and unaddressed challenges for earlier and more accurate establishment of OMD state. This review will provide an overview of the available imaging modalities and their inherent strengths and weaknesses, with a focus on their role and potential in detection and evaluation of OMD in different organ systems. Furthermore, we will review the role of imaging in evaluation of OMD for malignancies of various primary organs, such as the lung, prostate, colon/rectum, breast, kidney, as well as neuroendocrine tumors and gynecologic malignancies. We aim to provide a practical overview about the utilization of imaging for clinicians who play a role in the care of those with, or at risk for OMD.

Multifocal neuroendocrine tumour of the small bowel presenting as an incarcerated incisional hernia: a surgical challenge in a high-risk patient

Neuroendocrine tumours (NET) of the small bowel present significant clinical challenges, such as their rate of metastasis at initial presentation, common multifocality and understaging even with gold standard imaging. Here, we present a case of a high-risk surgical patient with a complex medical history initially presenting as an acute abdomen due to an incarcerated incisional hernia. He was found at emergency laparotomy to have three small NET deposits in a 30-cm segment of incarcerated ileum which was resected. Postoperative morphological and functional imaging and biochemical markers were unremarkable, but due to clinical suspicion for undetected residual tumour bulk given the non-systematic palpation of the entire small bowel at initial operation, underwent re-operation where a further 70 cm of ileum was found to harbour multiple tumour deposits (n = 25) and was resected. There was no surgical morbidity and the patient remains tumour-free at 9-month follow-up.

Hepatocellular carcinoma with biliary and neuroendocrine differentiation: A case report

BACKGROUND

Liver tumors with dual differentiations [combined hepatocellular carcinoma (HCC) and cholangiocarcinoma] are common. However, liver tumors that exhibit hepatocellular, biliary, and neuroendocrine differentiation are exceedingly rare, with only three previous case reports in the literature.

CASE SUMMARY

A 65-year-old female with a previous history of hepatitis C and a distant history of low grade, well-differentiated rectal neuroendocrine tumor was found to have two liver lesions in segment 4 and segment 7 on imaging. Serum alpha-fetoprotein and chromogranin A were elevated. Biopsy of the larger lesion in segment 4 revealed a high-grade tumor, with morphologic and immunohistochemical features of a neuroendocrine tumor. Given the previous history of rectal neuroendocrine tumor, imaging investigation, serologic markers, and biopsy findings, metastatic neuroendocrine tumor was considered. Subsequent regional resection of these hepatic lesions revealed the segment 4 lesion to be a HCC with additional biliary and neuroendocrine differentiation and the segment 7 lesion to be a cholangiocarcinoma with neuroendocrine differentiation. Follow-up of the patient revealed disease recurrence in the dome of the liver and metastasis in retro-pancreatic lymph nodes. The patient eventually expired due to complications of chemotherapy.

CONCLUSION

HCC cases with additional biliary and neuroendocrine differentiation are exceedingly rare, posing a diagnostic challenge for clinicians and pathologists.

The value of 68 Gallium-DOTATATE PET/CT in sinonasal neuroendocrine tumor management: A case series

BACKGROUND

⁶⁸ Gallium-DOTATATE (⁶⁸ Ga-DOTATATE) is a somatostatin analog used as a PET tracer to successfully identify neuroendocrine tumors (NETs). Due to the rarity of sinonasal NETs, there are few recommendations for ⁶⁸ Ga-DOTATATE imaging in these patients.

METHODS

We discussed the impact of ⁶⁸ Ga-DOTATATE imaging on the management of six sinonasal NET cases and reviewed existing literature.

RESULTS

⁶⁸ Ga-DOTATATE PET/CT revealed an unknown primary in one case and identified metastatic disease in a primary sinonasal small cell neuroendocrine carcinoma (SNEC) patient missed on conventional imaging. In two esthesioneuroblastoma (ENB) patients, ⁶⁸ Ga-DOTATATE detected abnormal radiotracer uptake not present on 18F-FDG PET/CT and identified a patient for treatment with ¹⁷⁷ Lu-DOTATATE.

CONCLUSIONS

This is the one of the first few reports, and the largest series to our knowledge, demonstrating the utility of ⁶⁸ Ga-DOTATATE imaging for primary sinonasal SNEC and ENB. Further study is required to determine its role in sinonasal NET management.

Knowns and unknowns of bone metastases in patients with neuroendocrine neoplasms: A systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis aimed to develop an evidence-based summary of current knowledge of bone metastases (BMs) in neuroendocrine neoplasms (NENs), inform diagnosis and treatment and standardise management between institutions.

METHODS

PubMed, Medline, EMBASE and meeting proceedings were searched for eligible studies reporting data on patients with BMs and NENs of any grade of differentiation and site; poorly-differentiated large/small cell lung cancer were excluded. Data were extracted and analysed using STATA v.12. Meta-analysis of proportions for calculation of estimated pooled prevalence of BM and calculation of weighted pooled frequency and weighted pooled mean for other variables of interest was performed .

RESULTS

A total of 149 studies met the eligibility criteria. Pooled prevalence of BMs was 18.4% (95% CI 15.4-21.5). BMs were mainly metachronous with initial diagnosis of NEN (61.2%) and predominantly osteoblastic; around 61% were multifocal, with a predisposition in axial skeleton. PET/CT seemed to provide (together with MRI) the highest sensitivity and specificity for BM detection. Almost half of patients (46.4%) reported BM-related symptoms: pain (66%) and skeletal-related events (SREs, fracture/spinal cord compression) (26.2%; weightedweighted mean time-to-SRE 9.9 months). Management of BMs was multimodal [bisphosphonates and bone-modifying agents (45.2%), external beam radiotherapy (34.9%), surgery (14.8%)] and supported by little evidence. Overall survival (OS) from the time of diagnosis of BMs was long [weighted mean 50.9 months (95% CI 40.0-61.9)]. Patients with BMs had shorter OS [48.8 months (95% CI 37.9-59.6)] compared to patients without BMs [87.4 months (95% CI 74.9-100.0); p = 0.001]. Poor performance status and BM-related symptoms were also associated with worse OS.

CONCLUSIONS

BMs in patients with NENs remain underdiagnosed and undertreated. Recommendations for management of BMs derived from current knowledge are provided. Prospective studies to inform management are required.

Consensus on molecular imaging and theranostics in neuroendocrine neoplasms

Nuclear medicine plays an increasingly important role in the management neuroendocrine neoplasms (NEN). Somatostatin analogue (SSA)-based positron emission tomography/computed tomography (PET/CT) and peptide receptor radionuclide therapy (PRRT) have been used in clinical trials and approved by the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA). European Association of Nuclear Medicine (EANM) Focus 3 performed a multidisciplinary Delphi process to deliver a balanced perspective on molecular imaging and radionuclide therapy in well-differentiated neuroendocrine tumours (NETs). NETs form in cells that interact with the nervous system or in glands that produce hormones. These cells, called neuroendocrine cells, can be found throughout the body, but NETs are most often found in the abdomen, especially in the gastrointestinal tract. These tumours may also be found in the lungs, pancreas and adrenal glands. In addition to being rare, NETs are also complex and may be difficult to diagnose. Most NETs are non-functioning; however, a minority present with symptoms related to hypersecretion of bioactive compounds. NETs often do not cause symptoms early in the disease process. When diagnosed, substantial number of patients are already found to have metastatic disease. Several societies' guidelines address Neuroendocrine neoplasms (NENs) management; however, many issues are still debated, due to both the difficulty in acquiring strong clinical evidence in a rare and heterogeneous disease and the different availability of diagnostic and therapeutic options across countries. EANM Focus 3 reached consensus on employing ⁶⁸gallium-labelled somatostatin analogue ([⁶⁸Ga]Ga-DOTA-SSA)-based PET/CT with diagnostic CT or magnetic resonance imaging (MRI) for unknown primary NET detection, metastatic NET, NET staging/restaging, suspected extra-adrenal pheochromocytoma/paraganglioma and suspected paraganglioma. Consensus was reached on employing ¹⁸fluorine-fluoro-2-deoxyglucose ([¹⁸F]FDG) PET/CT in neuroendocrine carcinoma, G3 NET and in G1-2 NET with mismatched lesions (CT-positive/[⁶⁸Ga]Ga-DOTA-SSA-negative). Peptide receptor radionuclide therapy (PRRT) was recommended for second line treatment for gastrointestinal NET with [⁶⁸Ga]Ga-DOTA-SSA uptake in all lesions, in G1/G2 NET at disease progression, and in a subset of G3 NET provided all lesions are positive at [¹⁸F]FDG and [⁶⁸Ga]Ga-DOTA-SSA. PRRT rechallenge may be used for in patients with stable disease for at least 1 year after therapy completion. An international consensus is not only a prelude to a more standardised management across countries but also serves as a guide for the direction to follow when designing new research studies.

Update on gastroenteropancreatic neuroendocrine tumors

The incidence gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) has dramatically risen over the last three decades, probably due to the increased detection of asymptomatic lesions. The diagnostic work-up for patients with suspected GEP-NENs is based on conventional imaging, endoscopy, pathology, and functional imaging, including ⁶⁸Gallium-DOTATATE PET and ¹⁸F-FDG PET. The choice of the best treatment strategy should be based on the evaluation of tumor-related features and patient's characteristics. A conservative management, consisting of active surveillance or endoscopic resection, has been advocated for patients with small, incidentally discovered, nonfunctioning tumors without features of aggressiveness. On the other hand, surgery with lymphadenectomy, also with a minimally invasive approach, represents the gold standard for the curative treatment of localized disease. Moreover, surgical resection plays an important role also in the context of a multimodal treatment strategy for patients with advanced GEP-NENs. Finally, a wide range of medical therapies, comprising somatostatin analogues, peptide receptor radionuclide therapy, target therapies and several chemotherapy regimens, can be offered to patients with advanced GEP-NENs not amenable of surgical resection, according to the biological and molecular features of their disease.

False-Positive Gallium-68 DOTATATE PET/CT in Vertebral Hemangioma

A healthy 52-year-old man started to have few minutes spells of palpitation, tachycardia, hot flashes, and chest tightness. He had a lab work-up for carcinoid, including 5-hydroxyindoleacetic acid (5-HIAA), which was negative. Months later, his symptoms became worse which warranted further investigation to exclude carcinoid disease. Gallium-68 DOTATATE positron emission tomography combined with computed tomography (PET/CT) scanning was performed to assess the patient for carcinoid tumor. It showed foci of radiotracer avidity in the thoracic and lumber spine. Magnetic resonance imaging (MRI) for the vertebral lesions showed atypical hemangioma. Subsequently, follow-up serum chromogranin A testing was negative.

Bone Metastases in Neuroendocrine Tumors: Molecular Pathogenesis and Implications in Clinical Practice

Skeletal colonization is often regarded as a rare event in patients with neuroendocrine tumors (NETs) although both national registries and retrospective series report an incidence of bone metastases as high as 20% in subjects with advanced disease. While the biological mechanisms leading to bone metastatic colonization in NETs have been poorly investigated so far, key steps of osteotropic mechanisms, including the epithelial-to-mesenchymal transition, preparation of the premetastatic niche, migration of circulating tumor cells towards the bone marrow as well as the resulting alterations of the skeletal metabolism, are likely to operate also during the development of NET bone metastases. The skeleton involvement by NETs has a detrimental impact on both quality of life and patients' prognosis, leading to pain in the majority of symptomatic subjects. While it is currently unclear whether or not the earlier recognition of bone involvement by PET/CT imaging techniques employing 68Ga-DOTA-conjugated peptides might improve outcomes through the exploitation of timely treatments, the management of bone-colonizing NETs is today based only on clinical experience from other osteotropic tumors. Here, we summarize the fundamental molecular mechanisms driving bone colonization and revisit both established and novel treatments for patients with bone metastatic NETs.

The Impact of 68Gallium DOTA PET/CT in Managing Patients With Sporadic and Familial Pancreatic Neuroendocrine Tumours

OBJECTIVE

Pancreatic neuroendocrine tumours (panNETs) arise sporadically or as part of a genetic predisposition syndrome. CT/MRI, endoscopic ultrasonography and functional imaging using Octreoscan localise and stage disease. This study aimed to evaluate the complementary role of ⁶⁸Gallium (⁶⁸Ga)-DOTA PET/CT in managing patients with panNETs.

DESIGN

A retrospective study conducted across three tertiary UK NET referral centres.

METHODS

Demographic, clinical, biochemical, cross-sectional and functional imaging data were collected from patients who had undergone a ⁶⁸Ga-DOTA PET/CT scan for a suspected panNET.

RESULTS

We collected data for 183 patients (97 male): median (SD) age 63 (14.9) years, 89.1 vs. 9.3% (n=163 vs. 17) alive vs. dead (3 data missing), 141 sporadic vs. 42 familial (MEN1, n=36; 85.7%) panNETs. Non-functional vs. functional tumours comprised 73.2 vs. 21.3% (n=134 vs. 39) (10 missing). Histological confirmation was available in 89% of individuals (n=163) but tumour grading (Ki67 classiifcation) was technically possible only in a smaller cohort (n=143): grade 1, 50.3% (n=72); grade 2, 46.2% (n=66) and grade 3, 3.5% (n=5) (40 histopathological classification either not technically feasible or biopsy not perfomed). 60.1% (n=110) were localised, 14.2% (n=26) locally advanced and 23.5% (n=43) metastatic (4 missing). 224 ⁶⁸Ga-DOTA PET/CT scans were performed in total for: diagnosis/staging 40% (n=88), post-operative assessment/clinical surveillance 53% (n=117) and consideration of peptide receptor radionuclide therapy (PRRT) 8% (n=17) (2 missing). PET/CT results confirmed other imaging findings (53%), identified new disease sites (28.5%) and excluded suspected disease (5%). Overall, ⁶⁸Ga-DOTA PET/CT imaging findings provided additional information in 119 (54%) patients and influenced management in 85 (39%) cases.

CONCLUSION

⁶⁸Ga-DOTA PET/CT imaging more accurately stages and guides treatment in patients with sporadic/familial panNETs with newly diagnosed/recurrent disease.