The Role of 68Ga-DOTATATE PET/CT in Suspected Neuroendocrine Tumors

Dual Somatostatin Receptor/18F-FDG PET/CT Imaging in Patients with Well-Differentiated, Grade 2 and 3 Gastroenteropancreatic Neuroendocrine Tumors

Our purpose was to prospectively assess the distribution of NETPET scores in well-differentiated (WD) grade 2 and 3 gastroenteropancreatic (GEP) neuroendocrine tumors (NETs) and to determine the impact of the NETPET score on clinical management. Methods: This single-arm, institutional ethics review board-approved prospective study included 40 patients with histologically proven WD GEP NETs. 68Ga-DOTATATE PET and 18F-FDG PET were performed within 21 d of each other. NETPET scores were evaluated qualitatively by 2 reviewers, with up to 10 marker lesions selected for each patient. The quantitative parameters that were evaluated included marker lesion SUVmax for each tracer; 18F-FDG/68Ga-DOTATATE SUVmax ratios; functional tumor volume (FTV) and metabolic tumor volume (MTV) on 68Ga-DOTATATE and 18F-FDG PET, respectively; and FTV/MTV ratios. The treatment plan before and after 18F-FDG PET was recorded. Results: There were 22 men and 18 women (mean age, 60.8 y) with grade 2 (n = 24) or grade 3 (n = 16) tumors and a mean Ki-67 index of 16.1%. NETPET scores of P0, P1, P2A, P2B, P3B, P4B, and P5 were documented in 2 (5%), 5 (12.5%), 5 (12.5%) 20 (50%), 2 (5%), 4 (10%), and 2 (5%) patients, respectively. No association was found between the SUVmax of target lesions on 68Ga-DOTATATE and the SUVmax of target lesions on 18F-FDG PET (P = 0.505). 18F-FDG/68Ga-DOTATATE SUVmax ratios were significantly lower for patients with low (P1-P2) primary NETPET scores than for those with high (P3-P5) primary NETPET scores (mean ± SD, 0.20 ± 0.13 and 1.68 ± 1.44, respectively; P < 0.001). MTV on 18F-FDG PET was significantly lower for low primary NETPET scores than for high ones (mean ± SD, 464 ± 601 cm3 and 66 ± 114 cm3, respectively; P = 0.005). A change in the type of management was observed in 42.5% of patients after 18F-FDG PET, with the most common being a change from systemic therapy to peptide receptor radionuclide therapy and from debulking surgery to systemic therapy. Conclusion: There was a heterogeneous distribution of NETPET scores in patients with WD grade 2 and 3 GEP NETs, with more than 1 in 5 patients having a high NETPET score and a frequent change in management after 18F-FDG PET. Quantitative parameters including 18F-FDG/68Ga-DOTATATE SUVmax ratios in target lesions and FTV/MTV ratios can discriminate between patients with high and low NETPET scores.

National practice patterns in the use of endoscopic ultrasound biopsy for resectable Pancreatic Neuroendocrine Tumors: Insights into the role of DOTATATE PET/CT in diagnosis

INTRODUCTION

Pancreatic neuroendocrine tumors (PNETs) are typically diagnosed using endoscopic ultrasound-guided (EUS) biopsy, which can be associated with complications. Since 2016, DOTATATE PET/CT has emerged as an effective tool to localize and stage PNETs.

METHODS

Patients with PNETs who underwent R0 resections were identified from the 2004-2019 National Cancer Database PUF. Joinpoint regression and multivariable logistic regression were used to analyze trends in the use of biopsy.

RESULTS

Of 16,746 R0 resected PNET patients, 44 ​% underwent diagnostic biopsy. Joinpoint regression showed a significant increase in the use of biopsy from 2004 to 2019 (APC 1.80, p ​< ​0.001). A higher percentage of patients diagnosed after DOTATATE approval underwent biopsy compared to those diagnosed before (48 ​% vs. 42 ​%, p ​< ​0.001). Adjusted analysis showed diagnosis after 2016 was associated with increased odds of biopsy (OR ​= ​1.67, p ​< ​0.001).

CONCLUSIONS

Despite technologic advancement with DOTATATE PET/CT, there has been a significant increase in the proportion of resectable PNETs undergoing preoperative biopsy.

Imaging and Metabolic Diagnostic Methods in the Stage Assessment of Rectal Cancer

Rectal cancer (RC) is a prevalent malignancy with significant morbidity and mortality rates. The accurate staging of RC is crucial for optimal treatment planning and patient outcomes. This review aims to summarize the current literature on imaging and metabolic diagnostic methods used in the stage assessment of RC. Various imaging modalities play a pivotal role in the initial evaluation and staging of RC. These include magnetic resonance imaging (MRI), computed tomography (CT), and endorectal ultrasound (ERUS). MRI has emerged as the gold standard for local staging due to its superior soft tissue resolution and ability to assess tumor invasion depth, lymph node involvement, and the presence of extramural vascular invasion. CT imaging provides valuable information about distant metastases and helps determine the feasibility of surgical resection. ERUS aids in assessing tumor depth, perirectal lymph nodes, and sphincter involvement. Understanding the strengths and limitations of each diagnostic modality is essential for accurate staging and treatment decisions in RC. Furthermore, the integration of multiple imaging and metabolic methods, such as PET/CT or PET/MRI, can enhance diagnostic accuracy and provide valuable prognostic information. Thus, a literature review was conducted to investigate and assess the effectiveness and accuracy of diagnostic methods, both imaging and metabolic, in the stage assessment of RC.

Comparison of 68Ga-DOTATATE Positron Emmited Tomography/Computed Tomography and Gadoxetic Acid-Enhanced Magnetic Resonance Imaging for the Detection of Liver Metastases from Well-Differentiated Neuroendocrine Tumors

This study aimed to compare the detection of neuroendocrine tumor liver metastases (NLMs) in hepatobiliary-specific contrast-enhanced MRI (pMR) versus 68Ga-DOTATATE PET/CT (DT-PET). This retrospective study cohort included 30 patients with well-differentiated neuroendocrine tumors who underwent both DT-PET and pMR. Two readers independently assessed NLMs count, SUVmax on DT-PET, and signal characteristics on pMR. A consensus review by two additional readers resolved discrepancies between the modalities. Results showed concordance between DT-PET and pMR NLM count in 14/30 patients (47%). pMR identified more NLMs in 12/30 patients (40%), of which 4 patients showed multiple deposits on pMR but only 0-1 lesions on DT-PET. DT-PET detected more in 4/30 patients (13%). Overall, pMR detected more metastases than DT-PET (p = 0.01). Excluding the four outliers, there was excellent agreement between the two methods (ICC: 0.945, 95%CI: 0.930, 0.958). Notably, pMR had a higher NLM detection rate than DT-PET, with correlations found between lesion size on pMR and DT-PET detectability, as well as diffusion restriction on pMR and SUVmax on DT-PET. In conclusion, in consecutive patients with well-differentiated NETs, the detection rate of NLM is higher with pMR than with DT-PET. However, when excluding patients whose tumors do not overexpress somatostatin receptors (13% of the cohort), high concordance in the detection of NLM is observed between DT PET and pMR.

68 Ga-DOTATATE PET to Characterize Lesions in the Neuroaxis

AIM

The differentiation of paragangliomas, schwannomas, meningiomas, and other neuroaxis tumors in the head and neck remains difficult when conventional MRI is inconclusive. This study assesses the utility of 68 Ga-DOTATATE PET/CT as an adjunct to hone the diagnosis.

PATIENTS AND METHODS

This retrospective study considered 70 neuroaxis lesions in 52 patients with 68 Ga-DOTATATE PET/CT examinations; 22 lesions (31%) had pathologic confirmation. Lesions were grouped based on pathological diagnosis and best radiologic diagnosis when pathology was not available. Wilcoxon rank sum tests were used to test for differences in SUV max among paragangliomas, schwannomas, and meningiomas. Receiver operator characteristic curves were constructed.

RESULTS

Paragangliomas had a significantly greater 68 Ga-DOTATATE uptake (median SUV max , 62; interquartile range [IQR], 89) than nonparagangliomas. Schwannomas had near-zero 68 Ga-DOTATATE uptake (median SUV max , 2; IQR, 1). Intermediate 68 Ga-DOTATATE uptake was seen for meningiomas (median SUV max , 19; IQR, 6) and other neuroaxis lesions (median SUV max , 7; IQR, 9). Receiver operator characteristic analysis demonstrated an area under the curve of 0.87 for paragangliomas versus all other lesions and 0.97 for schwannomas versus all other lesions.

CONCLUSIONS

Marked 68 Ga-DOTATATE uptake (>50 SUV max ) favors a diagnosis of paraganglioma, although paragangliomas exhibit a wide variability of uptake. Low to moderate level 68 Ga-DOTATATE uptake is nonspecific and may represent diverse pathophysiology including paraganglioma, meningioma, and other neuroaxis tumors but essentially excludes schwannomas, which exhibited virtually no uptake.

Accuracy of DOTATATE PET imaging in the preoperative planning of small bowel neuroendocrine tumor resection

BACKGROUND AND OBJECTIVES

We assessed the accuracy of preoperative gallium-68 DOTA-Tyr3-octreotate (DOTATATE) positron emission tomography (PET) imaging in estimating multifocality and nodal metastases of small bowel neuroendocrine tumors (sbNETs).

METHODS

A multicenter analysis was performed on patients with sbNETs who underwent preoperative DOTATATE PET imaging and surgical resection, with manual palpation of the entire length of the small bowel, between January 2016 and August 2022. Preoperative imaging reports and blinded secondary imaging reviews were compared to the final postoperative pathology reports. Descriptive statistics were applied.

RESULTS

One-hundred and four patients met inclusion criteria. Pathology showed 53 (51%) patients had multifocal sbNETs and 96 (92%) had nodal metastases. The original preoperative DOTATATE PET imaging identified multifocal sbNET in 28 (27%) patients and lymph node (LN) metastases in 80 (77%) patients. Based on original radiology reports, sensitivity for multifocal sbNET identification was 45%, specificity was 92%, positive predictive value (PPV) was 86%, and negative predictive value (NPV) was 62%. For the identification of LN metastases, sensitivity was 82%, specificity was 88%, PPV was 99%, and NPV was 29%.

CONCLUSIONS

Although DOTATATE PET imaging is specific and relatively accurate, sensitivity and NPV are insufficient to guide surgical planning. Preoperative use should not replace open palpation to identify additional synchronous lesions or to omit regional lymphadenectomy.

68Ga-DOTANOC PET/CT for Screening and Surveillance of Von Hippel-Lindau (VHL) disease

Purpose

Hereditary tumor syndrome Von Hippel-Lindau (VHL) disease is characterized by various benign and malignant tumors that are known to express somatostatin receptors (SSTR). We evaluated the role of 68Ga-DOTANOC PET/CT scan in patients with positive germline mutation of the VHL gene, presented initially or on follow-up, for the detection of recurrent or synchronous/metachronous lesions.

Methods

Fourteen patients (8 males; 6 females) with mean age 30 ± 9.86 years were retrospectively analyzed, were tested positive for VHL on gene dosage analysis, and underwent 68 Ga-DOTANOC PET/CT scan for disease evaluation. The number and site of lesions were determined. The tracer uptake was analyzed semi-quantitatively by calculating the maximum standardized uptake values (SUVmax) of lesion.

Results

Four of the 14 patients underwent scan for initial diagnosis as baseline, 6 patients for post-therapy disease status, and 4 patients for initial diagnosis as well as follow-up evaluation of the disease. A total of 67 lesions were detected in 14 patients. The sites of lesions were cerebellar/vertebral/spinal (17; mean SUVmax = 7.85); pancreatic neuroendocrine tumor (NET) (11; mean SUVmax = 20.64); retina (3; mean SUVmax = 10.46); pheochromocytoma (10; mean SUVmax = 16.32); paragangliomas (3; mean SUVmax = 10.65); pancreatic cyst (9; mean SUVmax = 2.54); and renal cyst (8; mean SUVmax = 1.56) and miscellaneous lesions constituted 6 lesions.

Conclusion

Our results show that 68 Ga-DOTANOC PET/CT may be a useful modality for screening and follow-up of associated tumors in patients with germline gene mutation for VHL. It can be used as a one-stop imaging modality for VHL patients and may substitute for separate radiological investigations, making it more convenient for patients in terms of time and cost.

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.

Early Definitive Diagnosis and Management of Incidental Neuroendocrine Tumors Found on Gastrointestinal Endoscopy

Neuroendocrine tumors (NETs) are tumors that originate from neuroendocrine cells and can be found throughout the body but are most commonly seen in the gastrointestinal tract, pancreas, and lungs. There is an increase in the diagnosis of NETs due to advances in diagnostic modalities. Although mucosal tumors are easily visualized on upper GI endoscopic imaging, neuroendocrine tumors are often missed due to their deep mucosal origin with normal overlying mucosa. We first present the case of a 46-year-old woman with anemia and epigastric discomfort who was found to have an incidental submucosal mass in the duodenal bulb on esophagogastroduodenoscopy (EGD), which on endoscopic ultrasound (EUS) with a fine needle biopsy (FNB) showed a neuroendocrine tumor. Imaging with CT, however, failed to detect the presence of the mass in the duodenum. Furthermore, a DOTATATE scan showed only a nonspecific signal near the liver. The patient then underwent an EGD-guided, laparoscopic, robot-assisted transduodenal resection of the tumor, together with the removal of enlarged peritumoral lymph nodes. Pathology showed a well-differentiated neuroendocrine tumor of the duodenal bulb with metastasis to one lymph node, which was confirmed via immunohistochemistry staining. The second case is of a 51-year-old female who presented with occasional constipation and rectal pain and was found to have a rectal polypoid lesion on her colonoscopy, jumbo biopsies of which revealed a NET. An EUS done for staging and endoscopic mucosal resection (EMR) revealed a grade 1 well-differentiated NET on pathology, which was confirmed by immunohistochemistry staining. These cases stress the need for timely, definitive diagnosis and intervention. Here, we discuss the clinical features and investigations of neuroendocrine tumors for early diagnosis and management.

Diagnostic performance of PET/CT in the detection of liver metastases in well-differentiated NETs

BACKGROUND

The aim of this retrospective study was to compare the diagnostic accuracy of somatostatin receptor (SSR)-PET/CT to liver MRI as reference standard in the evaluation of hepatic involvement in neuroendocrine tumors (NET).

METHODS

An institutional database was screened for "SSR" imaging studies between 2006 and 2021. 1000 NET Patients (grade 1/2) with 2383 SSR-PET/CT studies and matching liver MRI in an interval of +3 months were identified. Medical reports of SSR-PET/CT and MRI were retrospectively evaluated regarding hepatic involvement and either confirmed by both or observed in MRI but not in SSR-PET/CT (false-negative) or in SSR-PET but not in MRI (false-positive).

RESULTS

Metastatic hepatic involvement was reported in 1650 (69.2%) of the total 2383 SSR-PET/CT imaging studies, whereas MRI detected hepatic involvement in 1685 (70.7%) cases. There were 51 (2.1%) false-negative and 16 (0.7%) false-positive cases. In case of discrepant reports, MRI and PET/CT were reviewed side by side for consensus reading. SSR-PET/CT demonstrated a sensitivity of 97.0% (95%CI: 96.0%, 97.7%), a specificity of 97.7% (95%CI: 96.3%, 98.7%), a PPV of 99.0% (95%CI: 98.4%, 99.4%) and NPV of 93.0% (95%CI: 91.0, 94.8%) in identifying hepatic involvement. The most frequent reason for false-negative results was the small size of lesions with the majority < 0.6 cm.

CONCLUSION

This study confirms the high diagnostic accuracy of SSR-PET/CT in the detection of hepatic involvement in NET patients based on a patient-based analysis of metastatic hepatic involvement with a high sensitivity and specificity using liver MRI imaging as reference standard. However, one should be aware of possible pitfalls when a single imaging method is used in evaluating neuroendocrine liver metastases in patients.

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.

Feasibility and therapeutic potential of the 68Ga/177Lu-DOTATATE theranostic pair in patients with metastatic medullary thyroid carcinoma

BACKGROUND

This study assessed: 1) the clinical efficacy of imaging with 68Ga-DOTATATE PET/CT (SSTR (somatostatin receptor)-PET) to detect medullary thyroid carcinoma (MTC); and 2) the therapeutic efficacy of peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTATATE in MTC patients.

MATERIALS AND METHODS

Patients with histologically proven MTC and suspected recurrence following thyroidectomy, based on raised serum calcitonin levels, underwent SSTR-PET. In addition, to evaluate the clinical efficacy and safety of PRRT, the patients with intense uptake on SSTR-PET or 99mTc-octreotide scintigraphy underwent PRRT. The Common Terminology Criteria for Adverse Events (version 4.03) was used to grade adverse events after PRRT. Treatment response was classified as complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD).

RESULTS

Twenty MTC patients (10 male, 10 female) with a median age of 48.5 years underwent SSTR-PET. SSTR-PET was positive in 17/20 patients (85%). Four of the 17 patients with positive SSTR-PET were scheduled for PRRT. In addition, 2 patients had positive 99mTc-octreotide scintigraphy results (Krenning score ≥ 2) and were scheduled for PRRT. Two of the 6 patients who underwent PRRT showed PR, 2 SD and 2 PD. Two patients died during the follow-up period. Median overall survival was 19 months (95% CI: 5.52-29.48). There were no cases of significant toxicity.

CONCLUSION

Radiolabeled somatostatin analogs are contributive for the management of recurrent MTC. 68Ga-DOTATAE PET-CT showed a relatively high detection rate in recurrent MTC. In addition, PRRT with 177Lu-DOTATATE was found to be a safe alternative therapeutic option for MTC.

Molecular Characterization and Therapeutic Approaches to Small Cell Lung Cancer: Imaging Implications

Small cell lung cancer (SCLC) is a highly aggressive malignancy with exceptionally poor prognosis, comprising approximately 15% of lung cancers. Emerging knowledge of the molecular and genomic landscape of SCLC and recent successful clinical applications of new systemic agents have allowed for precision oncology treatment approaches. Imaging is essential for the diagnosis, staging, and treatment monitoring of patients with SCLC. The role of imaging is increasing with the approval of new treatment agents, including immune checkpoint inhibitors, which lead to novel imaging manifestations of response and toxicities. The purpose of this state-of-the-art review is to provide the reader with the latest information about SCLC, focusing on the subtyping of this malignancy (molecular characterization) and the emerging systemic therapeutic approaches and their implications for imaging. The review will also discuss the future directions of SCLC imaging, radiomics and machine learning.

Production Review of Accelerator-Based Medical Isotopes

The production of reactor-based medical isotopes is fragile, which has meant supply shortages from time to time. This paper reviews alternative production methods in the form of cyclotrons, linear accelerators and neutron generators. Finally, the status of the production of medical isotopes in China is described.

Pancreatic Incidentaloma

Pancreatic incidentalomas (PIs) represent a clinical entity increasingly recognized due to advances in and easier access to imaging techniques. By definition, PIs should be detected during abdominal imaging performed for indications other than a pancreatic disease. They range from small cysts to invasive cancer. The incidental diagnosis of pancreatic cancer can contribute to early diagnosis and treatment. On the other hand, inadequate management of PIs may result in overtreatment and unneeded morbidity. Therefore, there is a strong need to evaluate the nature and clinical features of individual PIs. In this review, we summarize the major characteristics related to PIs and present suggestions for their management.

The Impact of Total Variation Regularized Expectation Maximization Reconstruction on 68Ga-DOTA-TATE PET/CT Images in Patients With Neuroendocrine Tumor

Objective

The aim of this study was to investigate the effects of the total variation regularized expectation maximization (TVREM) reconstruction on improving 68Ga-DOTA-TATE PET/CT images compared to the ordered subset expectation maximization (OSEM) reconstruction.

Method

A total of 17 patients with neuroendocrine tumors who underwent clinical 68Ga-DOTA-TATE PET/CT were involved in this study retrospectively. The PET images were acquired with either 3 min-per-bed (min/bed) acquisition time and reconstructed with OSEM (2 iterations, 20 subsets, and a 3.2-mm Gaussian filter) and TVREM (seven penalization factors = 0.01, 0.07, 0.14, 0.21, 0.28, 0.35, and 0.42) for 2 and 3 min-per-bed (min/bed) acquisition time using list-mode. The SUVmean of the liver, background variability (BV), signal-to-noise ratios (SNR), SUVmax of the lesions and tumor-to-background ratios (TBR) were measured. The mean percentage difference in the SNR and TBR between TVREM with difference penalization factors and OSEM was calculated. Qualitative image quality was evaluated by two experienced radiologists using a 5-point score scale (5-excellent, 1-poor).

Results

In total, 63 lesions were analyzed in this study. The SUVmean of the liver did not differ significantly between TVREM and OSEM. The BV of all TVREM groups was lower than OSEM groups (all p &lt; 0.05), and the BV of TVREM 2 min/bed group with penalization factor of 0.21 was considered comparable to OSEM 3 min/bed group (p = 0.010 and 0.006). The SNR, SUVmax and TBR were higher for all TVREM groups compared to OSEM groups (all p &lt; 0.05). The mean percentage difference in the SNR and TBR was larger for small lesions (&lt;10 mm) than that for medium (≥10 mm but &lt; 20 mm) and large lesions (≥20 mm). The highest image quality score was given to TVREM 2 min/bed group with penalization factor of 0.21 (3.77 ± 0.26) and TVREM 3 min/bed group with penalization factor of 0.35 (3.77 ± 0.26).

Conclusion

TVREM could reduce image noise, improve the SNR, SUVmax and TBR of the lesions, and has the potential to preserves the image quality with shorter acquisition time.

Cyclic ACTH-secreting thymic carcinoid: a case report and review of the literature

Cyclic Cushing's syndrome (CS) due to thymic carcinoid is a rare disorder. We report a case of cyclic CS due to ectopic adrenocorticotropic hormone (ACTH)-secreting atypical thymic carcinoid tumor and reviewed similar cases published in the literature. Our patient had hypercortisolemia lasting approximately one month, followed by normal cortisol secretion, with relapse one year later. Histopathology revealed an atypical ACTH-positive thymic carcinoid. Ectopic CS can be derived from atypical thymic carcinoids, which can be aggressive tumors with early relapse, suggesting that this type of tumor probably needs aggressive treatment.

Patterns and predictors of pancreatic neuroendocrine tumor prognosis: Are no two leaves alike?

Pancreatic neuroendocrine tumors (PanNETs) are heterogeneous; thus, individual prognostic prediction is important. Clinicopathological features, like TNM stage, grade, and differentiation, are independent clinical predictors. However, single predictors are insufficient, as patients sharing similar clinicopathological features usually show distinct prognoses. Accordingly, novel nomograms and risk stratifications have been developed for more accurate PanNET prognostic prediction. Moreover, the exploration of molecular mechanisms has identified novel prognostic predictors for PanNET. Multi-analyte assays of molecular biomarkers provide a deeper understanding of PanNET features; however, the priority, and the optimal combination of classic and novel predictors for PanNET prognosis prediction remain unclear. In this review, we summarized the patterns and predictors of PanNET prognosis and discussed their clinical utility; we emphasized that PanNET at different stages have different superior predictor, and that multi-analyte assays are more sensitive than mono-analyte biomarkers. Therefore, combined biomarkers improve the accuracy of surveillance and optimize decision-making in clinical practice.

Incidental Finding of Squamous Cell Carcinoma on a 68Ga-DOTATATE PET Scan

Neuroendocrine tumors (NETs) are a relatively rare entity; however, the incidence and prevalence of these tumors are increasing, likely attributed to improved diagnostic accuracy. The diagnosis of suspected NETs is facilitated by clinical symptoms, laboratory test abnormalities such as elevated chromogranin-A, and other diagnostic modalities such as the use of computed tomography scans, magnetic resonance imaging scans, positron emission tomography (PET) scans, and biopsy. The expression of high levels of somatostatin receptors in NETs enables the use of a specialized PET scan using the radiolabeled somatostatin analogues 68Ga-DOTATATE. The sensitivity and specificity of 68Ga-DOTATATE PET is very high for the diagnosis of NETs, but the specificity decreases especially with no clear symptoms and with only borderline elevated tumor markers. We present a case of a suspected NET, which was initially diagnosed as a metastatic NET by virtue of a positive 68Ga-DOTATATE PET scan; however, on biopsy it was revealed to be a squamous cell carcinoma originating from the head and neck.

Feasibility and Therapeutic Potential of Combined Peptide Receptor Radionuclide Therapy With Intensive Chemotherapy for Pediatric Patients With Relapsed or Refractory Metastatic Neuroblastoma

BACKGROUND

Recent evidence has demonstrated high expression of somatostatin receptors in neuroblastoma (NB) cells. Because of this, we endeavored to evaluate the diagnostic performance and clinical efficacy of 68Ga-DOTATATE PET/CT and peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE combined with chemotherapy in pediatric NB patients.

PATIENTS AND METHODS

In total, 14 pediatric patients with histopathologically confirmed NB underwent 68Ga-DOTATATE PET/CT. Among them, the patients who were refractory or relapsed after therapy with 131I-MIBG and had intensive uptake of 68Ga-DOTATATE were referred for PRRT using 177Lu-DOTATATE. Treatment response based on follow-up imaging was classified into complete response, partial response, stable disease, and progressive disease. After each cycle of PRRT, laboratory tests were performed for evaluation of hematological, renal, and hepatic toxicities. The CTCAE (Common Terminology Criteria for Adverse Events; version 4.03) was used for grading adverse event. Curie score and International Society of Pediatric Oncology Europe Neuroblastoma score were used for semiquantitative analysis of scans of patients who underwent PRRT. In addition, overall survival was calculated as the time interval between the date of the first cycle and the end of follow-up or death.

RESULTS

Overall, 14 refractory NB children including 7 boys and 7 girls with a median age of 5.5 years (ranged from 4 to 9) underwent 68Ga-DOTATATE PET/CT. PET/CT was positive in 10/14 patients (71.4%), and the median number of detected lesions in positive patients was 2 (range, 1-13). Of 14 patients, 5 patients underwent PRRT, including 3 boys and 2 girls. A total of 19 PRRT cycles and 66.4 GBq 177Lu-DOTATATE were given. Among these 5 patients, 2 showed an initial complete response, which relapsed a few months later, 1 showed a partial response, and 2 showed progressive disease. According to the Kaplan-Meier test, the overall survival was estimated at 14.5 months (95% confidence interval, 8.9-20.1). In evaluation of PRRT-related toxicity according to the CTCAE, 4 patients showed grade 1, and 1 showed grade 2 leukopenia. Two patients showed grade 1, and 2 others showed grade 2 anemia. Two patients showed grade 1, and 3 patients showed grade 2 thrombocytopenia. Serum creatinine in 1 patient increased to grade 1.

CONCLUSIONS

Combination of 177Lu-DOTATATE with chemotherapeutic agents might achieve worthwhile responses with low toxicity, encouraging survival in NB patients who have relapsed or are refractory to conventional therapy, including 131I-MIBG therapy. Imaging with 68Ga-DOTATATE PET/CT in such patients has a relatively high detection efficacy, demonstrating its potential use as an alternative imaging tool to conventional modalities such as 123I/131I-MIBG. However, further well-designed trials are highly warranted.

Theragnostics in Neuroendocrine Tumors

Several studies have demonstrated the effectiveness of somatostatin receptor (SSTR)-targeted imaging for diagnosis, staging, evaluating the possibility of treatment with cold somatostatin analogs, as well peptide receptor radionuclide therapy (PRRT), and evaluation of treatment response. PET with ⁶⁸Ga-labeled somatostatin analogs provides excellent sensitivity and specificity for diagnosing and staging neuroendocrine tumors (NETs). Metabolic imaging with PET with fludeoxyglucose ¹⁸F/computed tomography (CT) complements the molecular imaging with ⁶⁸Ga-SSTR PET/CT toward a personalized therapy in NET patients. The documented response rate of PRRT in NET summing up complete response, partial response, minor response, and stable disease is 70% to 80%.

The value of [68Ga]Ga-DOTA-TATE PET/CT in diagnosis and management of suspected pituitary tumors

Background

Gallium 68-tetraazacyclododecane-tetraacetic acid-octreotate ([68Ga]Ga-DOTA-TATE) is a selective somatostatin analogue ligand, which shows increased affinity for somatostatin receptor subtype (SSTR) 2 and has been used routinely for imaging neuroendocrine tumors with PET/CT. We investigated the utility of [68Ga]Ga-DOTA-TATE positron emission tomography/computed tomography (PET/CT) in patients with suspected pituitary pathology. We reviewed imaging for twenty consecutive patients (8 men, 12 women, mean age of 48.2, range 14–78) with suspected pituitary pathology who were referred for [68Ga]Ga-DOTA-TATE PET/CT.

Results

Nine patients presented with recurrent Cushing’s syndrome following surgical resection of pituitary adenomas due to recurrent Cushing’s disease (seven patients) and ectopic ACTH secreting tumor (2 patients). All seven patients with recurrent Cushing’s disease showed positive pituitary [68Ga]Ga-DOTA-TATE uptake while both cases of ectopic hormonal secretion had absented pituitary uptake. In 1 of these 2 patients, [68Ga]Ga-DOTA-TATE was able to localize the source of ectopic ACTH tumor.

Six patients presented de novo with Cushing’s due to ectopic ACTH secretion; [68Ga]Ga-DOTA-TATE PET/CT was able to localize ectopic tumors in six of eight patients (3 lungs, 2 pancreases, 1 mid-gut)

There was high uptake [68Ga]Ga-DOTA-TATE in 3 cases of recurrent central hyperthyroidism (SUVmax 6.6–14.3) and 2 cases of prolactinoma (SUVmax 5.5 and 11.3).

Conclusion

Absent [68Ga]Ga-DOTA-TATE activity in the pituitary fossa is useful in excluding pituitary disease in recurrent Cushing’s. Recurrent pituitary thyrotropinomas and prolactinomas showed moderate to high pituitary activity. In addition, in Cushing’s syndrome, [68Ga]Ga-DOTA-TATE is useful for detection of ectopic sources of ACTH production, especially where anatomic imaging is negative.

Multimodality Imaging Review of Multiple Endocrine Neoplasia

OBJECTIVE. The purpose of this article is to review the clinical manifestations, endocrine tumors types, and multimodality diagnostic tools available to physicians involved in the management of patients with multiple endocrine neoplasia (MEN) syndrome, in addition to discussing relevant imaging findings and appropriate imaging follow-up. CONCLUSION. Thorough knowledge of the spectrum of tumors associated with MEN gene mutations aids in the screening, diagnostic workup, and posttreatment monitoring of patients with MEN-related gene mutations.

A Case Report: Insulinoma in a Military Pilot Detected by 68Ga-Dotatate PET/CT

A 37-year-old active duty male Air Force instructor pilot, with no prior medical history, was found unresponsive at his home after awakening with symptoms of altered mental status when the Emergency Medical Service (EMS) was called. The patient was found to be hypoglycemic with a glucose of 37 mg/dL. The patient recovered after administration of a dextrose bolus. Further investigation revealed that over the last several years, the patient exhibited symptoms of lightheadedness and tremors if fasted greater than 3 hours. Further clinical workup strongly suggested the presence of a neuroendocrine tumor. Initial imaging studies to include a multiphasic dedicated pancreatic computed tomography (CT) scan did not demonstrate a pancreatic lesion. However, the utilization of an innovative new nuclear medicine imaging modality, a 68Ga-Dotatate PET/CT, clearly demonstrated a 19 × 16 mm lesion of the distal pancreatic tail, which guided surgical resection. He underwent a robotic-assisted laparoscopic distal pancreatectomy, pathologically characterized as an insulinoma. The patient's symptoms immediately resolved with no recurrence over the next 6 months. The pilot was granted a waiver, returning him to his flying duties. The 68Ga-Dotatate PET/CT enabled the identification of an otherwise occult pancreatic neuroendocrine tumor ultimately leading to this patient's definitive cure and the salvage of this military asset's aviation career.

Surgical Management of Neuroendocrine Tumor Liver Metastases

Patients with neuroendocrine tumor liver metastases (NETLMs) may develop carcinoid syndrome, carcinoid heart disease, or other symptoms from overproduction of hormones. Hepatic resection and cytoreduction is the most direct treatment of NETLMs in eligible patients, and cytoreduction improves symptoms, may reduce the sequelae of carcinoid syndrome, and extends survival. Parenchymal-sparing procedures, such as ablation and enucleation, should be considered during cytoreduction to maximize treatment of multifocal tumors while preserving healthy liver tissue. For patients with large hepatic tumor burdens, high-grade disease, or comorbidities precluding surgery, liver-directed and systemic therapies can be used to palliate symptoms and improve progression-free survival.

Recent Advances in the Management of Typical and Atypical Lung Carcinoids

Neuroendocrine neoplasms of the lung represent about 20% to 30% of all neuroendocrine tumors. On the basis of clinical and pathologic characteristics, 2 different categories of tumors may be defined: poorly differentiated neuroendocrine neoplasms, characterized by a high rate of recurrences and poor prognosis, and well-differentiated neuroendocrine neoplasms (typical carcinoids and atypical carcinoids), which generally display an indolent course. Lung carcinoids represent only 1% to 5% of all lung malignancies, but their incidence has significantly increased over the past 30 years. Surgery is the reference standard of treatment for lung carcinoids with locoregional disease. For advanced or unresectable lung carcinoids, several therapeutic options are available, but the choice should be shared within a multidisciplinary team to ensure optimal therapeutic outcomes. We describe the current management of these rare neoplasms.

Diagnosis and management of small pulmonary atypical carcinoid tumor associated with Cushing syndrome

Ectopic adrenocorticotropic hormone (ACTH) syndrome is rare and identification of its source is often challenging. We report the case of an ectopic Cushing syndrome in a young adult male secondary to an occult ACTH producing atypical carcinoid tumor. Extensive biochemical and imaging workup was unrevealing. The diagnosis was aided by Ga-DOTA PET scan demonstrating a suspicious left upper lobe lung nodule. The patient underwent video-assisted thoracoscopic exploration with wedge resection and mediastinal lymphadenectomy of a T2aN2M0 atypical carcinoid, resulting in the normalization of ACTH levels and complete resolution of symptoms. The role of a Ga-DOTA PET scan in diagnosing pulmonary carcinoid tumors and their management are discussed.

Post FDA approval analysis of 200 gallium-68 DOTATATE imaging: A retrospective analysis in neuroendocrine tumor patients

Gallium-68 DOTATATE provides physiologic imaging and assists in disease localization for somatostatin receptor (SSTR) positive neuroendocrine tumor (NET) patients. However, questions regarding usefulness of gallium- 68 DOTATATE imaging in identifying the primary site in neuroendocrine tumors (NETS) of unknown primary, correlation of NET grade with median Standardized Uptake Value (SUV) and effects of long acting somatostatin analog on gallium-68 DOTATATE imaging quality needs to be evaluated. A single institution retrospective review of the first 200 NET patients with gallium-68 DOTATATE imaging from Dec 2016 to Dec 2017 was conducted. Questions related to NETs of unknown primary, correlation of Standardized Uptake Value (SUV) to Ki-67 (which signifies proliferation rate), the effects of long-acting systemic somatostatin analog (SSA) on SUV were part of our data analysis. From these 200 patients, 59.5% (119) were females, 40.5% (81) were males; the median age was 62 years. The following primary tumor sites were identified: small bowel-37.5%; pancreas-18.5%; bronchial-14%; colon-3.5%; rectum-2%; appendix-1.5%; adrenal-0.5%; prostate-0.5%; others-3% and unknown primary-19%. Mean hepatic SUV of the lesion with the greatest radiolabeled uptake in 96 patients was similar irrespective to exposure to long acting SSA. Patients exposed to long acting SSA had mean SUV of 31.3 vs 27.8 for SSA naïve patients. The difference was not statistically significant. Gallium-68 DOTATATE imaging seems to distinguished G3 NET from G1/G2 based on mean SUV, and also identified the primary tumor site in 17 of 38 (45%) patients with unknown primary. Systemic exposure to long acting SSA does not appear to influence mean SUV of gallium-68 DOTATATE scan.

Treatment Outcomes in Patients with Metastatic Neuroendocrine Tumors: a Retrospective Analysis of a Community Oncology Database

Purpose

Metastatic neuroendocrine tumors (mNETs) are rare, heterogeneous tumors that present diagnostic and treatment challenges, with limited data on the management of mNETs in clinical practice. The present study was designed to identify current diagnostic and treatment patterns in mNET patients treated in the US community oncology setting.

Methods

Patient-level data was collected from medical records of adults with mNETs from the Vector Oncology Data Warehouse, a comprehensive US community oncology network database.

Results

Of the 263 patients included (median follow-up, 22 months; range, 0.1–193.9), 30.4% (80/263) had intestinal tumors, 11.0% (29/263) had pancreatic, and 58.6% (154/263) had tumors of other or unknown location. Progression-free survival (PFS) from the start of first-line therapy differed significantly by tumor grade (log rank P = 0.0016) and location (P = 0.0044), as did overall survival (OS) (grade, P < 0.0001; location, P = 0.0068). Median PFS and OS for patients with undocumented tumor grade were shorter than for patients with G1/G2 tumors and longer than patients with G3 tumors. Median PFS and OS for patients with other or unknown tumors were shorter than for patients with intestinal tumors.

Conclusions

While potentially confounded by the high number of patients with other or unknown tumor locations, this retrospective study of patients in a US community oncology setting identified the importance of awareness of tumor grade and tumor location at diagnosis, as these were direct correlates of PFS and OS.

A pan-cancer analysis of the clinical and genetic portraits of somatostatin receptor expressing tumor as a potential target of peptide receptor imaging and therapy

Purpose

Although somatostatin receptor (SST) is a promising theranostic target and is widely expressed in tumors of various organs, the indication for therapies targeting SST is limited to typical gastroenteropancreatic neuroendocrine tumors (NETs). Thus, broadening the scope of the current clinical application of peptide receptor radiotherapy (PRRT) can be supported by a better understanding of the landscape of SST-expressing tumors.

Methods

SST expression levels were assessed in data from The Cancer Genome Atlas across 10,701 subjects representing 32 cancer types. As the major target of PRRT is SST subtype 2 (SST2), correlation analyses between the pan-cancer profiles, including clinical and genetic features, and SST2 level were conducted. The median SST2 expression level of pheochromocytoma and paraganglioma (PCPG) samples was used as the threshold to define “high-SST2 tumors.” The prognostic value of SST2 in each cancer subtype was evaluated by using Cox proportional regression analysis.

Results

We constructed a resource of SST expression patterns associated with clinicopathologic features and genomic alterations. It provides an interactive tool to analyze SST expression patterns in various cancer types. As a result, eight of the 31 cancer subtypes other than PCPG had more than 5% of tumors with high-SST2 expression. Low-grade glioma (LGG) showed the highest proportion of high-SST2 tumors, followed by breast invasive carcinoma (BRCA). LGG showed different SST2 levels according to tumor grade and histology. IDH1 mutation was significantly associated with high-SST2 status. In BRCA, the SST2 level was different according to the hormone receptor status. High-SST2 status was significantly associated with good prognosis in LGG patients. High-SST2 status showed a trend for association with poor prognosis in triple-negative breast cancer subjects.

Conclusion

A broad range of SST2 expression was observed across diverse cancer subtypes. The SST2 expression level showed a significant association with genomic and clinical aspects across cancers, especially in LGG and BRCA. These findings extend our knowledge base to diversify the indications for PRRT as well as SST imaging.

Bench-to-Bedside Theranostics in Nuclear Medicine

The optimum selection of the appropriate radiolabelled probe for the right target and the right patient is the foundation of theranostics in personalised medicine. In nuclear medicine, this process is realised through the appropriate choice of radiopharmaceuticals based on molecular biomarkers regarding molecular imaging. Theranostics is developing a strategy that can be used to implement accepted tools for individual molecular targeting, including diagnostics, and advances in genomic molecular knowledge, which has led to identifying theranostics biomaterials that have the potency to diagnose and treat malignancies. Today, numerous studies have reported on the discovery and execution of these radiotracers in personalised medicine. In this review, we presented our point of view of the most important theranostics agents that can be used to treat several types of malignancies. Molecular targeted radionuclide treatment methods based on theranostics are excellent paradigms of the relationship between molecular imaging and therapy that has been used to provide individualised or personalised patient care. Toward that end, a precise planned prospective examination of theranostics must be done to compare this approach to more standard therapies.

DO2A-based ligands for gallium-68 chelation: synthesis, radiochemistry and ex vivo cardiac uptake

New DO2A-based lipophilic and cationic chelators for gallium-68 have been synthesised for cardiac PET imaging. These radiotracers show preferential uptake in healthy cardiac tissue over cardiac tissue depolarised by CCCP.

Quantitative 3D Assessment of 68Ga-DOTATOC PET/MRI with Diffusion-Weighted Imaging to Assess Imaging Markers for Gastroenteropancreatic Neuroendocrine Tumors: Preliminary Results

⁶⁸Ga-DOTATOC PET/MRI combines the advantages of PET in the acquisition of metabolic-functional information with the high soft-tissue contrast of MRI. SUVs in tumors have been suggested to be a measure of somatostatin receptor expression. A challenge with receptor ligands is that the distribution volume is confined to tissues with tracer uptake, potentially limiting SUV quantification. In this study, various functional 3-dimensional SUV apparent diffusion coefficient (ADC) parameters and arterial tumor enhancement were tested for ability to characterize gastroenteropancreatic (GEP) neuroendocrine tumors (NETs). Methods: For this single-center, cross-sectional study, 22 patients with 24 histologically confirmed GEP NET lesions (15 men and 7 women; median age, 61 y; range, 43-81 y) who underwent hybrid ⁶⁸Ga-DOTA PET/MRI at 3 T between January 2017 and July 2019 met the eligibility criteria. SUV, tumor-to-background ratio, total functional tumor volume, and mean and minimum ADC were measured on the basis of volumes of interest and examined with receiver-operating-characteristic analysis to determine cutoffs for differentiation between low- and intermediate-grade GEP NETs. The Spearman rank correlation coefficient was used to assess correlations between functional imaging parameters. Results: The ratio of PET-derived SUV_mean and diffusion-weighted imaging-derived minimum ADC was introduced as a combined variable to predict tumor grade, outperforming single predictors. On the basis of a threshold ratio of 0.03, tumors could be classified as grade 2 with a sensitivity of 86% and a specificity of 100%. SUV and functional ADCs, as well as arterial contrast enhancement parameters, showed nonsignificant and mostly negligible correlations. Conclusion: Because receptor density and tumor cellularity appear to be independent, potentially complementary phenomena, the combined ratio of PET/MRI and SUV_mean/ADC_min may be used as a novel biomarker allowing differentiation between grade 1 and grade 2 GEP NETs.

Spleen Scan for 68Ga-DOTATOC PET-Positive Pancreatic Tail Lesion: Differential Diagnosis of Neuroendocrine Tumor from Accessory Spleen

⁶⁸Ga-DOTATOC PET/CT is widely used as a functional imaging technique in the detection and characterization of neuroendocrine tumors (NETs). Pancreatic NET and intrapancreatic accessory spleen (IPAS) have similar radiologic characteristics in anatomical imaging and usually show high uptake of ⁶⁸Ga-DOTATOC. Thus, it is challenging to make a differential diagnosis between NET and IPAS when the tumor-like lesion is located in the pancreatic tail. Here, we present a case of ⁶⁸Ga-DOTATOC PET-positive pancreatic tail lesion with high arterial enhancement on CT and MRI. Since ^99mTc-labeled damaged red blood cell does not accumulate on NET, a negative spleen scan finding was a crucial diagnostic step to decide surgical resection, which was histologically proven as insulinoma. Our case shows a promising role of additional use of spleen scan with SPECT/CT for the differential diagnosis of ⁶⁸Ga-DOTATOC PET-positive pancreatic NET from the accessory spleen.

Molecular imaging of a glucagonoma with 18F-FDG PET/CT and 68Ga-DOTATATE PET/CT imaging: A case report and review of the literature

A 35-year-old man presented with significant weight loss of 30 kg over the previous 6 months, with newly diagnosed diabetes. Routine laboratory tests were normal, except for markedly elevated blood glucose. Computed tomography (CT) of the abdomen revealed a large severely enhanced mass replacing most of the pancreas and liver metastatic nodules and multiple paraaortic lymph node metastases, ¹⁸F-fluorodeoxygluocse positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) was performed and revealed mild FDG uptake in the pancreatic mass, as well as mild uptake in the liver and lymph node metastases. A biopsy of the liver metastasis was consistent glucagonoma that was confirmed with markedly elevated serum glucagon level. Subsequently, ⁶⁸Ga-DOTATATE PET/CT was performed for better tumor characterization and for assessment of the tumors’ response to therapy, ⁶⁸Ga-DOTATATE scan revealed intense uptake in the pancreatic mass, liver metastases, and paraaortic lymph node metastases. The patient responded well to peptide receptor radionuclide therapy. This case highlights the role of both ⁶⁸Ga-DOTATATE and ¹⁸FDG-PET/CT in the diagnosis and management of a glucagonoma. ⁶⁸Ga-DOTATATE is the tracer of choice for well-differentiated glucagonoma and offers very high diagnostic accuracy as compared with that of cross-sectional and other functional imaging and enables correct patient selection for peptide receptor radionuclide therapy.

Characteristics of 252 patients with bronchopulmonary neuroendocrine tumours treated at the Copenhagen NET Centre of Excellence

BACKGROUND

Bronchopulmonary neuroendocrine tumours are divided into typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC), and small cell lung cancer (SCLC).

AIM

To thoroughly describe a cohort of 252 patients with TC, AC and LCNEC (SCLC excluded).

MATERIAL AND METHODS

Collection of data from 252 patients referred to and treated at Rigshospitalet 2008-2016. Data was collected from electronic patient files and our prospective NET database. Statistics were performed in SPSS.

RESULTS

162 (64%) had TC, 29 (12%) had AC and 61 (24%) had LCNEC. Median age at diagnosis was 69 years (range: 19-89) with no difference between genders. Thoraco-abdominal CT was performed in all patients at diagnosis. FDG-PET/CT was performed in 207 (82%) at diagnosis and was positive in 95% of the entire cohort, with no difference between tumour types. Synaptophysin was positive in 98%, chromogranin A in 92% and CD56 in 97%. Mean Ki67 index was 5% in TC, 16% in AC and 69% in LCNEC (p < 0.001). Metastatic disease was found in 4% of TC, 27% of AC and 58% of LCNEC at time of initial diagnosis (p < 0.001). In total 179 patients (71%) underwent surgical resection; TC: 87%, AC: 72% and LCNEC: 28% (p < 0.001). Of the resected patients, 11 (6%) had recurrence. Five-year survival rate was 88% for TC, 63% for AC and 20% for LCNEC.

CONCLUSION

In this comprehensive study of a cohort of 252 patients, one of the largest until date, with TC, AC and LCNEC, the gender distribution showed female predominance with 68%. FDG-PET/CT was positive in 95% of the patients independent of tumour type, which confirms that FDG-PET/CT should be a part of the preoperative work-up for TC, AC and LCNEC. Tumour type was the single most potent independent prognostic factor.

Evaluating the Role of Theranostics in Grade 3 Neuroendocrine Neoplasms

The diagnosis and subsequent therapy of neuroendocrine neoplasms (NENs) have long relied on somatostatin receptor (SSTR) expression. The field of theranostics now uses newer SSTR-based PET imaging with ⁶⁸Ga-DOTATATE or ⁶⁸Ga-DOTATOC as a prerequisite for the administration of peptide receptor radionuclide therapy (PRRT). In the United States, Food and Drug Administration approval of ¹⁷⁷Lu-DOTATATE, a form of PRRT, in 2018 for use in gastroenteropancreatic NENs was obtained on the basis of prolonged progression-free survival versus high-dose octreotide long-acting release in a phase III clinical trial of well-differentiated midgut NENs. Well-differentiated grade 1 and grade 2 NENs have a low proliferation index (Ki-67 < 20%) and longer overall survival (>10 y), whereas higher-grade (grade 3 [G3]) NENs have a high Ki-67 (>20%) and shorter overall survival (<1 y). Here, we present a review on the role of SSTR-based imaging and PRRT in G3 NENs, including a discussion of well-differentiated G3 NENs, the newest histologic classification. Some studies suggest that G3 NENs are less likely to be positive on SSTR-based imaging (but more likely on ¹⁸F-FDG PET) than are well-differentiated NENs, but these data are limited. We found only 13 studies mentioning the use of PRRT in G3 NENs and a total of only 151 patients across these studies in whom radiologic response was measured. Of these 151 patients, 99 (66%) demonstrated at least stable disease or a partial response, indicating that some G3 NENs can be responsive to PRRT. We suggest that patients with G3 NENs should receive both ¹⁸F-FDG PET and SSTR-based imaging to aid in both diagnosis and treatment selection, as positivity on SSTR-based imaging helps with patient identification for PRRT and discordance may suggest important clues to tumor biology and prognosis. However, prospective studies are needed to fully understand the role of PRRT in G3 NENs, especially in well- versus poorly differentiated G3 disease.

[68Ga]-Dota Peptide PET/CT in Neuroendocrine Tumors: Main Clinical Applications

Objective:

Neuroendocrine Neoplasms (NENs) are generally defined as rare and heterogeneous tumors. The gastrointestinal system is the most frequent site of NENs localization, however they can be found in other anatomical regions, such as pancreas, lungs, ovaries, thyroid, pituitary, and adrenal glands. Neuroendocrine neoplasms have significant clinical manifestations depending on the production of active peptide.

Methods:

Imaging modalities play a fundamental role in initial diagnosis as well as in staging and treatment monitoring of NENs, in particular they vastly enhance the understanding of the physiopathology and diagnosis of NENs through the use of somatostatin analogue tracers labeled with appropriate radioisotopes. Additionally, the use of somatostatin analogues provides the ability to in-vivo measure the expression of somatostatin receptors on NEN cells, a process that might have important therapeutic implications.

Results:

A large body of evidences showed improved accuracy of molecular imaging based on PET/CT radiotracer with SST analogues (e.g. [68Ga]-DOTA peptide) for the detection of NEN lesions in comparison to morphological imaging modalities. So far, the role of imaging technologies in assessing treatment response is still under debate.

Conclusion:

This review offers the systems of classification and grading of NENs and summarizes the more useful recommendations based on data recently published for the management of patients with NENs, with special focus on the role of imaging modalities based on SST targeting with PET / CT radiotracers.

Whole-Body Staging of Metastatic Atypical Meningioma Using 68Ga-DOTATATE PET/CT

A 43-year-old woman with suspected recurrence of atypical meningioma World Health Organization grade II presented extensive intracranial lesions with high Ga-DOTATATE uptake. Moreover, numerous Ga-DOTATATE-positive bone, lung, and liver lesions were seen. For final diagnosis, biopsies taken from a lung lesion revealed distant metastases of the atypical meningioma. This case underlines the high diagnostic power of Ga-DOTATATE PET/CT for the staging of meningioma even beyond cerebral or spinal lesions; in case of distant lesions in patients with known meningioma, differential diagnosis should also contain metastases despite their rare occurrence. Moreover, this case emphasizes radioligand therapy especially in metastatic meningioma.

Management of Primary Lymph Nodal Gastrinoma With Liver Metastases Resulting in Zollinger-Ellison Syndrome

Primary lymph node gastrinoma has been defined as gastrin-producing tumor present in lymph nodes and predominantly found in well-defined anatomical region known as gastrinoma triangle. They are usually localized preoperatively with imaging, and their surgical resection results in long-term relief. The authors report a case of unresectable primary lymph nodal gastrinoma with liver metastases in a 14-year-old adolescent boy with proven histopathology detected on Ga-DOTANOC whole-body PET/CT scan followed by preoperative multiple Lu-DOTATATE cycles for cytoreduction. Subsequent surgical resection of residual mass resulted in complete response with a follow-up of around 4 years in this unusual case of Zollinger-Ellison syndrome.

Pleuropulmonary tuberculosis with spinal lesions due to metastatic malignancy differentiated definitively on imaging

A healthy 31-year-old man presenting with back pain was found to have multiple spinal enhancing lesions on MRI. An incidental asymptomatic large pleural effusion was identified on investigations for the back pain and pleural and pulmonary tuberculosis (TB) was subsequently diagnosed. The radiographical features on MRI spine were not typical of spinal TB and a Ga68 DOTATATE Positron Emission Tomography (PET)/CT confirmed metastatic paraganglioma with multiple bone metastases. Although metastatic paraganglioma is rare, this case highlights that even in young patients dual pathology needs to be considered. Most importantly, it is a reminder to physicians managing TB of the clues that help distinguish spinal TB from important alternative causes, including metastatic malignancy.

Management of Typical and Atypical Pulmonary Carcinoids Based on Different Established Guidelines

Neuroendocrine tumors (NETs) are a group of malignancies that originated from neuroendocrine cells, with the most common sites being lungs and the gastrointestinal tract. Lung NETs comprise 25% of all lung malignancies. Small cell lung cancer is the most common form of lung NETs, and other rare forms include well-differentiated typical carcinoids (TCs) and poorly differentiated atypical carcinoids (ACs). Given the paucity of randomized studies, rational treatment is challenging. Therefore, it is recommended that these decisions be made using a multidisciplinary collaborative approach. Surgery remains the mainstay of treatment, when feasible. Following surgery, various guidelines offer different recommendations in the adjuvant setting. In this paper, we describe the adjuvant management of lung NETs, as recommended by different guidelines, and highlight their differences. In addition to that, we also discuss the management of metastatic lung NETS, including the use of peptide receptor radionucleotide therapy.

The utility of 68Gallium-DOTATATE PET/CT in the detection of von Hippel-Lindau disease associated tumors

PURPOSE

Patients with von Hippel-Lindau (VHL) disease may develop various tumors, including neuroendocrine tumors of the pancreas (PNETs) and adrenal, central nervous system and retinal hemangioblastomas, kidney tumors and more. ⁶⁸Ga-DOTATATE positron emission tomography (PET)/computerized tomography (CT) has been shown to be highly accurate for tumors with cells expressing somatostatin receptors. We aimed to assess the performance of ⁶⁸Ga-DOTATATE PET/CT in patients with VHL disease.

METHODS

Patients with a diagnosis of VHL were enrolled in a prospective study and underwent surveillance imaging for pancreatic lesions (n = 301). The current analysis includes 73 evaluations with multiple imaging modalities of 36 patients (2.1 ± 0.8 evaluations/patient, range 1-4) for a head-to-head comparison of ⁶⁸Ga-DOTATATE PET/CT, CT and/or MRI. In this post-hoc analysis we compared the detection rates of various imaging modalities for PNETs and for any extrapancreatic tumors located within the scan field of CT/MRI of the abdomen.

RESULTS

⁶⁸Ga-DOTATATE PET/CT detected a total of 206 lesions, CT detected 208 lesions and MRI detected 94 lesions in 61, 66 and 33 scans, respectively. ⁶⁸Ga-DOTATATE PET/CT (3.4 ± 0.1 per scan) was superior than CT (3.2 ± 0.1 per scan, p = 0.02) with a similar trend when comparing with MRI (2.8 ± 0.1 per scan, p = 0.03) in detecting lesions in any anatomic locations.

CONCLUSIONS

⁶⁸Ga-DOTATATE PET/CT had a significantly higher detection rate when compared with anatomic imaging for all lesions, and comparable detection rate for pancreatic lesions in VHL patients. Hence, given the higher accuracy and lower radiation exposure associated with ⁶⁸Ga-DOTATATE PET/CT, its potential role in the surveillance of VHL-associated lesions should be further studied.

Evolution of a Schmorl's Node and a Degenerative Osteophyte on Sequential 68Ga-DOTATATE PET/CT Scans: Potential Pitfalls in Neuroendocrine Tumor Imaging

Schmorl's node (SN) arises from the herniation of the nucleus pulposus of the disc through the cartilaginous endplate into the body of the vertebra. Our report describes a patient with carcinoid tumor who underwent a series of Ga-DOTATATE PET/CT scans for follow-up, demonstrating gradually increasing focal vertebral uptake in absence of CT abnormality, suspicious for a metastasis. Both CT and MRI eventually revealed classical findings of a SN. Also observed in the same vertebra is a degenerative osteophyte showing intense Ga-DOTATATE uptake. This interesting case shows 2 benign spinal lesions, which potentially can simulate bone metastasis in patients with neuroendocrine tumors.

Diagnosing microscopic pancreatic neuroendocrine tumor using 68-Ga-DOTATATE PET/CT: case series

Neuroendocrine tumors (NETs) are an uncommon diagnosis which often present asymptomatically or with vague symptoms. They can originate from many different organs such as the GI tract, lungs, pancreas and others. ⁶⁸Gallium DOTATATE positron emission topography/computed topography has been shown to be an effective imaging modality for diagnosing NET and evaluating management options for patients. Here, we present two cases of positive findings in the distal pancreas on the DOTATATE PET/CT scans without any morphological lesion found to be NET in a healthy 48-year-old male and 68-year-old male.

Everolimus in the treatment of neuroendocrine tumors: efficacy, side-effects, resistance, and factors affecting its place in the treatment sequence

INTRODUCTION

Since the initial approval of everolimus in 2011, there have been a number of important changes in therapeutic/diagnostic modalities as well as classification/staging systems of neuroendocrine tumors (NETs), which can significantly impact the use of everolimus in patients with advanced NETs. Areas covered: The efficacy of everolimus monotherapy and combination therapy demonstrated in clinical studies involving patients with advanced NETs are reviewed. Several factors affecting everolimus use are described including: the development and routine use of NET classification/staging systems; widespread use of molecular imaging modalities; side effects; drug resistance; and the availability of other treatment options. Furthermore, the current position of everolimus in the treatment approach is discussed, taking into account the recommendations from the recent guidelines. Expert opinion: Although everolimus demonstrated its high efficacy and tolerability in the RADIANT trials and other clinical studies, there still remain a number of controversies related to everolimus treatment in the management of NETs. The synergistic anti-growth effect of other agents in combination with everolimus or its effect on overall survival have not been established. The appropriate order of the use of everolimus in the treatment of advanced NETs still remains unclear, which needs to be defined in further studies and will be addressed in the new guidelines.