Prediction of lymph node metastasis of well-differentiated rectal neuroendocrine tumours using multiple diagnostic modalities

AIM

The preoperative prediction of lymph node metastasis of well-differentiated rectal neuroendocrine tumours is highly desirable and useful in defining surgical indication more accurately. We aimed to evaluate lymph node metastasis in rectal neuroendocrine neoplasms using multiple imaging modalities.

METHODS

The clinical records and radiological images of 70 patients with well-differentiated rectal neuroendocrine tumours who received treatment at the University of Tokyo Hospital between 2010 and 2022 were retrospectively analysed. The relationship between evaluation by multiple imaging modalities and pathological lymph node metastasis was analysed.

RESULTS

The receiver operating characteristic curves showed that a maximum lymph node diameter ≥4 mm on computed tomography and ≥8 mm on magnetic resonance imaging were the optimal predictive factors for lymph node metastasis. Accumulation in the lymph nodes on somatostatin receptor scintigraphy (P = 0.058) and Delle's findings on colonoscopy (P = 0.014) were also significant predictors of pathological lymph node positivity, and combination of multiple modalities was useful. Pathologically, lymphatic (P = 0.0030)/venous (P = 0.0007) invasion were risk factors for lymph node metastasis.

CONCLUSIONS

In addition to pathological risk factors, a combination of multiple radiological imaging modalities is useful for predicting lymph node metastasis in well-differentiated rectal neuroendocrine tumours.

Prospective Multicentric Assessment of (68)Ga-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.

Diagnostic work-up and advancement in the diagnosis of gastroenteropancreatic neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplasms ranging from well-differentiated, slowly growing tumors to poorly differentiated carcinomas. These tumors are generally characterized by indolent course and quite often absence of specific symptoms, thus eluding diagnosis until at an advanced stage. This underscores the importance of establishing a prompt and accurate diagnosis. The gold-standard remains histopathology. This should contain neuroendocrine-specific markers, such as chromogranin A; and also, an estimate of the proliferation by Ki-67 (or MIB-1), which is pivotal for treatment selection and prognostication. Initial work-up involves assessment of serum Chromogranin A and in selected patients gut peptide hormones. More recently, the measurement of multiple NEN-related transcripts, or the detection of circulating tumor cells enhanced our current diagnostic armamentarium and appears to supersede historical serum markers, such as Chromogranin A. Standard imaging procedures include cross-sectional imaging, either computed tomography or magnetic resonance, and are combined with somatostatin receptor scintigraphy. In particular, the advent of ¹¹¹In-DTPA-octreotide and more recently PET/CT and ⁶⁸Ga-DOTA-Octreotate scans revolutionized the diagnostic landscape of NENs. Likewise, FDG PET represents an invaluable asset in the management of high-grade neuroendocrine carcinomas. Lastly, endoscopy, either conventional, or more advanced modalities such as endoscopic ultrasound, capsule endoscopy and enteroscopy, are essential for the diagnosis and staging of gastroenteropancreatic neuroendocrine neoplasms and are routinely integrated in clinical practice. The complexity and variability of NENs necessitate the deep understanding of the current diagnostic strategies, which in turn assists in offering optimal patient-tailored treatment. The current review article presents the diagnostic work-up of GEP-NENs and all the recent advances in the field.

Treatment Outcomes in Neuroendocrine Prostate Cancer

BACKGROUND/AIM

Neuroendocrine prostate cancer (NEPC) is rare and has a poor prognosis; its clinical course and treatment outcomes are also unclear. This study investigated the clinical characteristics, clinical course, and treatment outcomes of patients with NEPC.

PATIENTS AND METHODS

This retrospective study investigated 14 patients histologically diagnosed with NEPC at Kanazawa University Hospital between 2000 and 2019. Overall survival (OS) and progression-free survival (PFS) were retrospectively analyzed using the Kaplan-Meier method. Additionally, log-rank tests were used to compare survival distributions.

RESULTS

We included 14 patients histologically diagnosed with NEPC among 1,845 patients with prostate cancer. Four patients (0.22%) were diagnosed with de novo NEPC, and ten patients were diagnosed with NEPC during treatment. First-line platinum-based therapy's objective response rate (ORR) was 66.7%, and disease control rate was 91.7%; median PFS was 7.5 months. The median OS from NEPC diagnosis was 20.3 months. The median OS of the liver metastasis (-) group was 31.6 months, and that of the (+) group was 9.4 months (p=0.03, hazard ratio=0.24). The median OS of the somatostatin receptor scintigraphy (SRS)-positive group was 31.6 months, and that of the SRS-negative group was 10.6 months (p=0.04, hazard ratio=0.14).

CONCLUSION

Platinum-based chemotherapy is effective to some extent, but the duration of response is not sufficient; therefore, new treatment options are needed. This is the first study to show that SRS findings and the presence of liver metastases might be prognostic predictors of NEPC.

Retrospective study of peptide receptor radionuclide therapy for Japanese patients with advanced neuroendocrine tumors

Background

Peptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin analogs is an innovative treatment for advanced somatostatin‐positive neuroendocrine tumors (NETs). PRRT cannot be performed in Japan because there is no approval or insurance cover so far.

Methods

We relied on foreign institutions to perform PRRT for Japanese patients with NETs. We retrospectively evaluated the safety and efficacy of PRRT. The inclusion criteria were pathologically confirmed well‐differentiated NET and visible tumor uptake on pre‐therapeutic somatostatin receptor scintigraphy. ¹⁷⁷Lu‐DOTA‐TOC was used as the standard treatment, and patients received three infusions every 8 weeks. Until the end of 2017, combination treatment with ⁹⁰Y and ¹⁷⁷Lu‐DOTA‐TOC was performed using the same protocol.

Results

Thirty‐five patients were evaluated, and the primary lesions were pancreas, rectum, small intestine, stomach, and other locations. The partial response rate was 42.9%. Progression‐free survival (PFS) was 12.8 months and overall survival was 42.8 months. There was no significant difference in PFS between front‐line and late‐line PRRT (11.0 months vs 28.0 months; P = .383). Severe adverse events included lymphocytopenia (20.0%) and thrombocytopenia (5.7%). Myelodysplastic syndrome occurred in one case.

Conclusion

PRRT was effective and safe for Japanese patients with advanced NETs. PRRT was equally effective as front‐line and late‐line treatment.

Mediastinal Cystic Parathyroid Adenoma Diagnosed by Somatostatin Receptor Scintigraphy

A 71-year-old man complained of nausea and loss of appetite for eight months prior to admission. He was transported to a hospital with disorientation and diagnosed with primary hyperparathyroidism by laboratory examinations. However, ultrasonography, computed tomography, and technetium-99m labeled methoxyisobutyl isonitrile (^99mTc-MIBI) with single-photon emission computed tomography did not yield definite results. In contrast, somatostatin receptor scintigraphy successfully identified the lesion responsible for the over-secretion of parathyroid hormone within the middle mediastinum. The tumor was successfully resected by surgery, and a histopathological analysis confirmed the parathyroid adenoma nature of the tumor.

Somatostatin Receptor Scintigraphy in a Patient with Myocarditis

We report a case of myocarditis imaged with technetium-99m octreotide cardiac single-photon emission computed tomography which showed diffuse uptake in the myocardium, indicating inflammatory reaction to myocardial damage. Somatostatin receptor scintigraphy of the heart could be considered in patients with suspected cardiac inflammation. This could facilitate early diagnosis and guide appropriate treatment.

Somatostatin receptor molecular imaging in a misdiagnosed gastrinoma case

Gastrin-secreting tumors, hypergastrinemia and severe ulcer disease form the trademarks of Zollinger-Ellison syndrome (ZES). We report a case of gastrinoma, in a patient who was misdiagnosed for almost five years. The case emphsizes the the special role of functional imaging in the personalized approach to the patient with suggestive symptomatology for NETs. Taking into account that in 80 to 100% of cases of gastroenteropancreatic (GEP) NETs are expressing somatostatin receptors, the functional imaging with radiolabeled somatostatin analogues can be used in order to improve its diagnosis, respectively the treatment of GEP NETs. In the approach to the patient with tremendous digestive symptomatology, physicians from different specialties should evaluate NETs specific markers and then insist on structural-functional complementarity, avoiding the waste of time and high cost of repeated structural investigations. The conclusion of our study is that functional imaging is mandatory in the diagnostic algorithm of gastrinoma.

Evaluation of a Correction Method for 111In-Pentetreotide SPECT Imaging of Gastroenteropancreatic Neuroendocrine Tumors

The number of patients with the extremely rare disease gastroenteropancreatic (GEP) neuroendocrine tumor (NET) has increased rapidly in recent years. ¹¹¹In-pentetreotide SPECT in somatostatin receptor scintigraphy has been used for the assessment of GEP NET patients. To diagnose GEP NET, appropriate selection of image correction parameters is critical. Correction methods may improve the ¹¹¹In-pentetreotide SPECT image quality, but there is currently no standard technique. The purpose of this study was to determine the optimal correction parameter settings for ¹¹¹In-pentetreotide SPECT. Methods: A phantom study produced images with a tumor-to-background ratio of as high as 16:1. A triple energy window was used for scatter correction (SC), and attenuation correction (AC) was CT-based. Correlation analysis was performed in 4 groups: no correction (NC), SC, AC, and combined SC with AC (CC). The ¹¹¹In-pentetreotide SPECT results for 20 randomly selected patients (13 men and 7 women; age range, 37-81 y) with confirmed GEP NET were analyzed using data collected 4 h after injection of 111 MBq of ¹¹¹In-pentetreotide. Emission data were reconstructed using ordered-subset expectation maximization (OSEM) with different settings. Different combinations of the correction parameters were used to analyze the contrast-to-noise ratios (CNRs) obtained with the phantom. In the clinical study, 20 GEP NET patients were used to evaluate the GEP NET lesion CNR by 4 different image correction methods obtained from ¹¹¹In-pentetreotide SPECT images: NC, SC, AC, and CC. NC was used as a reference method. Results: The phantom study revealed that the optimal energy window in the photopeak for somatostatin receptor scintigraphy was 171 keV ± 10% and 245 keV ± 7.5%, and the optimal OSEM reconstruction conditions were 8 subsets and 6 iterations. Among the OSEM collection conditions, CC produced a significantly higher CNR than NC or SC (P < 0.05). In the clinical study, CC was found to increase the CNR (P < 0.05). Conclusion: CC improves the correction in ¹¹¹In-pentetreotide SPECT studies, compared with NC, providing better contrast and sharper outlines of lesions and organs.

Long-term Survival of a Patient with Small Cell Lung Cancer Secreting ADH and ACTH Simultaneously, Following the Prolonged Use of Amrubicin

Paraneoplastic syndromes are frequently observed in lung cancer, especially in small cell lung cancer (SCLC). Although there have been many reports on paraneoplastic syndromes, few reports have been published on SCLC that simultaneously produces antidiuretic hormone (ADH) and adrenocorticotropic hormone (ACTH), and these reports described the prognosis of such cases as extremely poor. We herein present a rare case of a Japanese woman with SCLC accompanied by syndrome of inappropriate secretion of antidiuretic hormone (SIADH) and Cushing's syndrome. The survival of the patient was prolonged by the long-term administration of amrubicin.

A case of gallbladder neuroendocrine carcinoma diagnosed preoperatively using somatostatin receptor scintigraphy

Gallbladder neuroendocrine carcinoma (NEC) is a rare gallbladder tumor. The current report is a case of a patient preoperatively diagnosed with gallbladder NEC using somatostatin receptor scintigraphy (SRS). A 63-year-old man was admitted to our hospital by a family doctor after abdominal ultrasonography revealed thickened walls of the neck of his gallbladder. At Kagoshima University Hospital, CT and MRI of the abdomen and endoscopic ultrasonography confirmed the thickening of the walls of the neck of the gallbladder. However, it did not resemble a typical gallbladder cancer or tumor, such as a neuroendocrine tumor or malignant lymphoma. Positron emission tomography and SRS showed abnormal accumulation at the tumor site. Endoscopic retrograde cholangiopancreatography was performed, adenocarcinoma was suspected based on intra-gallbladder bile cytology, and a cholecystectomy with lymphadenectomy was performed. The postoperative pathological diagnosis was small cell NEC (pT3a, N0, M0, stage II). Immunohistochemistry indicated that the gallbladder tumor cells were positive for synaptophysin, chromogranin A, and cluster of differentiation (CD) 56, and negative for somatostatin receptors (SSTR) 2 and 5. Gene expression assays revealed the expression of all SSTR subtypes (SSTR1-5) in the tumor. Generally, NECs exhibit poor accumulation in SRS, however, the results of the current case suggest that SRS may be useful in the preoperative diagnosis of NEC.

Value of Somatostatin Receptor Scintigraphy with 99mTc-HYNIC-TOC in Patients with Primary Sjögren Syndrome

Objectives: Primary Sjögren syndrome (SS) is diagnosed based on the American European Consensus Group (AECG) criteria, but lacks specificity, not only in the involvement of salivary glands, but also in extra-glandular involvement. Whole-body somatostatin receptor scintigraphy with ^99mTc-HYNIC-TOC scintigraphy could overcome these limitations. The aims of this study were to evaluate salivary gland uptake of ^99mTc-HYNIC-TOC in untreated patients with de-novo diagnosis of SS as compared to control subjects and as compared to conventional sialoscintigraphy with ^99mTcO₄⁻. We also aimed to evaluate the involvement of joints. Methods: ^99mTc-HYNIC-TOC was used with SS patients and uptake in joints and salivary glands was analyzed semi-quantitatively. Patients also underwent ^99mTcO₄ sialoscintigraphy. The control group that we analyzed consisted of 30 patients with neuroendocrine tumors. Results: Fifty-two females and 10 males fully met the AECG criteria for SS, and were included. A target background ratio (TBR) >1.18 in submandibular glands correctly classified 93% of the patients with SS in comparison to 27% for ^99mTcO₄ sialoscintigraphy. The area under the curve (ROC) analysis for TBR in submandibular glands was 0.95. In joints there was a huge variety in uptake. The median TBR was significantly higher in salivary glands in patients with SS compared to controls. Conclusions: ^99mTc-HYNIC-TOC scintigraphy identified active inflammatory processes not only in the salivary glands, but, unexpectedly, also in many joints in patients with primary SS, contrary to popular belief. This technique provides an objective parameter to evaluate the inflammation burden in salivary glands and joints and could be used to evaluate response to treatment.

Cerebellar metastasis of papillary thyroid carcinoma detected with somatostatin receptor scintigraphy

INTRODUCTION

Distant metastases of papillary thyroid carcinoma (PTC) may lack the ability to concentrate radioiodine. In such cases, positive somatostatin receptor scintigraphy might be useful in demonstrating the expression of somatostatin receptors that are potential therapeutic targets. To date, only a few cerebellar metastases from PTC have been reported in the literature.

PATIENT FINDINGS

We present an 82-year-old female, in whom an asymptomatic cerebellar metastasis from PTC was diagnosed by means of Tc-99m-EDDA/HYNIC-TOC scintigraphy four years after the initial diagnosis. She was previously treated with total thyroidectomy and regional lymph node dissection, followed by three cycles of radioiodine therapy. Despite persistently elevated thyroglobulin, no specific radioiodine accumulation was found in the whole body post-treatment scan. Tc-99m-EDDA/HYNIC-TOC scintiscan revealed foci of increased tracer uptake in the lungs, cervical lymph nodes, and a single focus in the head. Thus, therapy with octreotide LAR was initiated. The patient died four months later due to disseminated PTC.

SUMMARY

In this paper, a patient with asymptomatic previously unknown non-iodine avid cerebellar metastasis of PTC diagnosed by means of scintigraphy using somatostatin analogue Tc-99m-EDDA/HYNIC-TOC is reported.

CONCLUSIONS

Somatostatin receptor scintigraphy might be useful in the visualisation of non-iodine avid PTC metastases and demonstrat-ing the expression of somatostatin receptors that are potential therapeutic targets.

Molecular radiotheranostics for neuroendocrine tumours

This article discusses the important role of nuclear medicine imaging and therapy in the management of neuroendocrine tumours (NETs). Somatostatin receptor scintigraphy has a high impact on patient management versus conventional imaging. Molecular radiotherapy is an important part of the management of patients with NETs. Selection of patients for molecular radiotherapy in NETs is based on uptake on their radionuclide imaging study. The imaging agent has the same mechanism of uptake as the therapeutic agent. Thus, the imaging study preselects patients that are likely to concentrate radiation within their tumours.

Gallium-68 in Medical Imaging

Over the past several years, Positron Emission Tomography (PET) imaging agents labeled with ;68Gallium (68Ga) have undergone a significant increase in clinical utilization. 68Ga is conveniently produced from a germanium-68/gallium-68 (68Ge/68Ga) generator. Because of the compact size and ease of use of the generator, 68Ga labeled compounds may be more cost-effective than PET radioisotopes that are cyclotron-produced. The convenient half-life of 68Ga (T1/2=68 min) provides sufficient radioactivity for various PET imaging applications, while delivering acceptable radiation doses to patients. This chapter summarizes the emerging clinical utilization of 68Ga-based radiotracers in medical imaging.

Limitations and pitfalls of 99mTc-EDDA/HYNIC-TOC (Tektrotyd) scintigraphy

Tektrotyd kit was developed by Polatom company for 99mTc labeling to make an alternative tracer of somatostatin receptor scintigraphy available. Since 2005, 99mTc-EDDA/HYNIC-Tyr3-Octreotide has been used in clinical imaging and achieved high impact in management of patients with neuroendocrine tumors. Knowing the limitations and pitfalls is essential to provide ac-curate diagnosis. Therefore, the potential pitfalls associated with the use of 99mTc-EDDA/HYNIC-TOC are reviewed on the basis of own experience. Data were analyzed of 310 patients who underwent somatostatin receptor scintigraphy with 99mTc-Tektrotyd. Pitfalls during radiolabeling process or acquisition can worsen the sensitivity of SRS (somatostatin receptor scintigraphy). Recognizing physi-ological and clinical pitfalls, the diagnostic accuracy will improve.

Waiting to deliver a final diagnosis

We report a patient with left eye positional transient visual obscurations, diplopia, a left afferent pupillary defect, and optic disk edema-all occurring during pregnancy. Noncontrast magnetic resonance imaging revealed an orbital mass encasing the optic nerve and extending through the superior orbital fissure into the cavernous sinus. An magnetic resonance imaging with gadolinium after parturition and strongly positive somatostatin receptor scintigraphy suggested the diagnosis of meningioma. Biopsy confirmed the diagnosis, and she was treated with CyberKnife stereotactic radiosurgery. In cases of atypical presentation, somatostatin receptor scintigraphy can help distinguish optic nerve sheath meningioma from alternative orbital masses.

An evaluation of the effects of somatostatin analogue therapy in non-functioning pituitary adenomas in comparison to acromegaly

INTRODUCTION

Non-functioning pituitary adenomas (NFPA) are often diagnosed late as invasive macroadenomas. The surgical resection is usually incomplete and about 50% of patients require additional surgery. Recent data suggest that somatostatin analogues (SSA), so important in the pharmacotherapy of acromegaly, can also be effective in the management of NFPA.

MATERIAL AND METHODS

We analysed data of patients who had been treated up to 10 years previously with SSA: 40 with acromegaly (23 - primary, 17 - recurrent tumours) and 22 with NFPA (4 - primary, 18 - recurrent tumours). Hormonal profile, dynamics of tumour size change, ophthalmic syndromes, somatostatin receptor (SSTR) scintigraphy, and immunohistochemistry of SSTR subtypes of operated tumours as well as side effects were investigated.

RESULTS

Biochemical cure of acromegaly was achieved in 57.5% of patients, while reduction of tumour size was observed in 37% of patients and it was more frequent in not-operated cases. Regarding NFPA, stabilisation of tumour size was noticed in 68% of patients. Tumour shrinkage was reported in 9% of cases, but in 23% of the study group the adenoma size increased with indication for reoperation.

CONCLUSIONS

The efficacy of SSA in NFPA is much lower in comparison to their well-established effects in the treatment of acromegaly. Stabilisation of tumour size, which is observed in the majority of NFPA, is significantly more frequent in comparison to the natural history of untreated NFPA and our previous studies as well. Analysis of SSTR subtypes is an argument in favour of introduction of novel broad-spectrum SSA that may be more effective in the treatment of NFPA. Referring to acromegaly, adenoma size decrease was reported more frequently in primary therapy. Considering recurrent tumours better outcomes were achieved in patients who were pre-treated with SSA before planned surgery. (Endokrynol Pol 2016; 67 (3): 292-298).

Neuroendocrine differentiation in castration-resistant prostate cancer: A case report

The most common type of prostate cancer is acinar adenocarcinoma, which is androgen-dependent and, therefore, treated with chemical or surgical castration and androgen receptor inhibition. However, the disease usually progresses to castration-resistant prostate cancer (CRPC). A neuroendocrine pattern is frequently observed in the cellular composition of CRPC, which is considered to emerge as an effect of androgen deprivation therapy. This is the case report of a 69-year-old patient with prostate adenocarcinoma, who, after an initial period of disease control with radiotherapy and antiandrogens, was diagnosed with CRPC with high levels of prostate-specific antigen (PSA), unresponsive to androgen inhibition, with accompanying lung and osseous metastases. Bronchial biopsy of the lung metastasis revealed infiltration by non-small-cell adenocarcinoma of prostatic origin with neuroendocrine characteristics. On somatostatin receptor scintigraphy with ^99mTc-octreotide, there was high uptake by almost all known lung and osseous metastases. The patient was subsequently treated with a combination of docetaxel and octreotide, and a partial response was observed 6 months later, with reduction of the PSA level and the size of the lung metastasis. The aim of the present study was to provide a clinical example of the previously demonstrated, in vitro and in vivo, synergistic antitumor activities of docetaxel and octreotide in cases of CRPC selected by means of histological confirmation of their neuroendocrine nature and somatostatin receptor scintigraphy.

Nuclear medicine techniques in Merkel cell carcinoma: A case report and review of the literature

Merkel cell carcinoma (MCC) is a rare and aggressive type of neuroendocrine cancer of the skin. It predominantly affects the elderly, with a predilection for the sun-exposed skin of the head and neck. Risk factors include immune-suppressing diseases, such as human immunodeficiency virus (HIV), chronic lymphocytic leukemia and multiple myeloma, organ transplantation, and the presence of the newly-identified Merkel cell polyomavirus (MCPyV). Diagnosis is based on pathological findings, primarily the immunohistochemical determination of cytokeratin 20 positivity. By contrast, staging relies on conventional imaging methods, such as ultrasonography, computed tomography (CT) and magnetic resonance imaging, and nuclear medicine techniques, such as sentinel lymph node scintigraphy, somatostatin receptor scintigraphy (SRS), and positron emission tomography (PET)/CT with ¹⁸F-fluorodeoxyglucose (FDG) or alternative radiopharmaceuticals. The treatment of MCC is primarily surgical, with possible adjuvant radiation, while the use of chemotherapy appears to be an alternative therapeutic option that is used only in specific cases. The present study describes the case of a 43-year-old HIV-positive Caucasian man with MCC located on the posterior surface of the left thigh, which was identified by cytological and histological examination of tissue sampled by fine needle aspiration and biopsy performed under CT. SRS demonstrated a high uptake of ¹¹¹In-diethylene triamine pentaacetic acid-octreotide at the affected site. Therefore, the lesion was surgically excised, and the patient received chemotherapy and adjuvant radiotherapy. Three months subsequent to treatment, the patient underwent a PET/CT scan with ¹⁸F-FDG that demonstrated uptake in the cervical lymph nodes and the area of the excised lesion. These findings indicated that the disease was in remission. The aim of the present study was to highlight the value and contribution of nuclear medicine in the diagnosis, staging and follow-up, using PET/CT, octreoscan and sentinel lymph node scintigraphy, of patients with MCC, as well as the therapeutic strategy of radiolabelled somatostatin analogue scintigraphy.

18F-fluorodihydroxyphenylalanine PET/CT in patients with neuroendocrine tumors of unknown origin: relation to tumor origin and differentiation

This work was performed to evaluate the performance of (18)F-fluorodihydroxyphenylalanine ((18)F-FDOPA) PET/CT in detecting primary neuroendocrine tumors (NETs) occult on morphologic and functional imaging, in relation to tumor origin and differentiation.

METHODS

A retrospective study of NET patients who were investigated with (18)F-FDOPA PET/CT imaging in 2 academic endocrine tumor centers was conducted. Only patients with negative conventional and somatostatin receptor scintigraphy (SRS) results were studied.

RESULTS

Twenty-seven patients were evaluated with (18)F-FDOPA PET/CT, 23 at their initial staging and 4 during their follow-up. The primary occult NET was localized by (18)F-FDOPA PET/CT in 12 patients (overall sensitivity, 44%; 52% in patients evaluated at initial diagnosis), leading to tumor resection in all cases. The primary tumors were distributed and graded as follows: 1 duodenum G2 lesion, 7 ileum G2 lesions, 2 terminal ileum G1 lesions, 1 pancreas G2 lesion, and 1 gallbladder G3 lesion. Patients with positive (18)F-FDOPA PET/CT results had higher values of serum chromogranin A (100% vs. 20%, P = 0.0003), serotonin, or urinary 5-hydroxyindolacetic acid (83% vs. 20%, P = 0.003). Two false-negative results were related to poorly differentiated duodenal and prostatic NETs (G3). (18)F-FDOPA PET/CT showed more metastatic anatomic regions than SRS in 17 patients.

CONCLUSION

(18)F-FDOPA PET appears to be a sensitive functional imaging tool for the detection of primary NETs occult on SRS, especially tumors with a well-differentiated pattern and serotonin secretion.

Nuclear medicine imaging of gastro-entero-pancreatic neuroendocrine tumors. The key role of cellular differentiation and tumor grade: from theory to clinical practice

Nuclear medicine imaging is a powerful diagnostic tool for the management of patients with gastro-entero-pancreatic neuroendocrine tumors, mainly developed considering some cellular characteristics that are specific to the neuroendocrine phenotype. Hence, overexpression of specific trans membrane receptors as well as the cellular ability to take up, accumulate, and decarboxylate amine precursors have been considered for diagnostic radiotracer development. Moreover, the glycolytic metabolism, which is not a specific energetic pathway of neuroendocrine tumors, has been proposed for radionuclide imaging of neuroendocrine tumors. The results of scintigraphic examinations reflect the pathologic features and tumor metabolic properties, allowing the in vivo characterization of the disease. In this article, the influence of both cellular differentiation and tumor grade in the scintigraphic pattern is reviewed according to the literature data. The relationship between nuclear imaging results and prognosis is also discussed. Despite the existence of a relationship between the results of scintigraphic imaging and cellular differentiation, tumor grade and patient outcome, the mechanism explaining the variability of the results needs further investigation.

Diagnostic work-up of gastroenteropancreatic neuroendocrine tumors

Neuroendocrine tumors are a heterogeneous group of malignancies that present a diagnostic challenge. The majority of patients (more than 60%) present with metastatic disease at diagnosis. The diagnosis is based on histopathology, imaging, and circulating biomarkers. The histopathology should contain specific neuroendocrine markers such as chromogranin A, synaptophysin, and neuron-specific enolase and also an estimate of the proliferation by Ki-67 (MIB1). Standard imaging procedures consist of computed tomography or magnetic resonance imaging together with somatostatin receptor scintigraphy. 68Ga-DOTA-octreotate scans will in the future replace somatostatin receptor scintigraphy because they have higher specificity and sensitivity. Other positron imaging tomographic scanning tracers that will come into clinical use are 18F-DOPA and 11C-5HTP. Neuroendocrine tumors secrete many different peptides and amines that can be used as circulating biomarkers. The most useful general marker is chromogranin A, which is both a diagnostic and prognostic marker in most neuroendocrine tumors. However, there is still a need for improved biomarkers for early detection and follow-up of patients during treatment. In addition, molecular imaging can be further developed for both detection and evaluation of treatment.

Automatic and manual image fusion of In-pentetreotide SPECT and diagnostic CT in neuroendocrine tumor imaging - An evaluation

In the clinical diagnosis of neuroendocrine tumors (NET), the results of examinations, such as high-resolution computed tomography (CT) and single photon computerized tomography (SPECT), have conventionally been interpreted separately. The aim of the present study was to evaluate Hermes Multimodality™ 5.0 H Image Fusion software-based automatic and manual image fusion of SPECT and CT for the localization of NET lesions. Out of 34 NET patients who were examined by means of somatostatin receptor scintigraphy (SRS) with 111In- pentetreotide along with SPECT, 22 patients had a CT examination of the abdomen, which was used in the fusion analysis. SPECT and CT data were fused using software with a registration algorithm based on normalized mutual information. The criteria for acceptable fusion were established at a maximum cranial or caudal dislocation of 25 mm between the images and at a reasonable consensus (in order of less than 1 cm) between outline of the reference organs. The automatic fusion was acceptable in 13 of the 22 examinations, whereas 9 fusions were not. However all the 22 examinations were acceptable at the manual fusion. The result of automatic fusion was better when the slice thickness of 5 mm was applied at CT examination, when the number of slices was below 100 in CT data and when both examinations included uptakes of pathological lesions. Retrospective manual image fusion of SPECT and CT is a relatively inexpensive but reliable method to be used in NET imaging. Automatic image fusion with specified software of SPECT and CT acts better when the number of CT slices is reduced to the SPECT volume and when corresponding pathological lesions appear at both SPECT and CT examinations.

Molecular imaging of neuroendocrine tumors

Molecular imaging represents tissue-specific imaging and quantification of physiologically functional and molecular events in tumors, utilizing new noninvasive imaging modalities. It combines anatomic, physiologic and metabolic information in a single imaging session. Neuroendocrine tumors (NETs) present unique features to use specific nuclear imaging, such as somatostatin receptor scintigraphy (SRS), metaiodobenzylguanidine scans and PET scanning. NETs express somatostatin receptors on tumor cells and can, thus, be visualized by ¹¹¹In-gadolinium-diethylenetriame pentaacetic acid-octreotide (OctreoScan^®), which is currently the most common scanning technique for NETs. Every patient with a NET should be subjected to SRS. Technetium-labeled somatostatin analogs are currently growing in importance. Metaiodobenzylguanidine scanning was previously the only method for detection and follow-up of NETs, but is nowadays more or less replaced by octreotide scanning. During the last decade, PET scanning has been developed for detection and follow-up of patients with NETs. It has clearly demonstrated the highest sensitivity and specificity in the range of 85-95%. It detects smaller tumors down to 3 mm, compared with SRS, which has a size limit of approximately 1 cm. ⁶⁸Ga-DOTA-octreotide will, in the future, replace SRS owing to its higher sensitivity and specificity, and also reduce the time for investigation. It will also offer the possibility to evaluate the number of somatostatin receptors in a specific tumor. In the future, PET scanning will be more readily available and less expensive, and it will be possible to study tumor biology, vascularization and gene expression in NETs with the development of new tracers.

Gastric carcinoid tumors

Initially, carcinoid tumors were a curiosity for physicians and were so named because of their relatively benign behavior as compared to the more common adenocarcinomas. As medicine has evolved, our understanding and management have greatly improved. Our classification system has also become more specific. Gastric carcinoid tumors are unique in that three types have been described based upon each one's pathophysiology. In general, none of these give rise to the typical carcinoid syndrome as seen with metastatic ileal carcinoids.Type 1 gastric carcinoids represent 70% to 80% and are characterized by multiple small lesions and their association with hypergastrinemia secondary to chronic atrophic gastritis and pernicious anemia, and are less likely to metastasize. Type 2 is a rare entity, representing 5%, and is characterized by multiple small lesions, hypergastrinemia secondary to Zollinger-Ellison syndrome, and multiple endocrine neoplasia (MEN) type 1. The risk for metastasis is slightly higher than for type 1; however, overall prognosis is dependent upon the gastrinoma prognosis. Accounting for 20%, type 3 is known as sporadic gastric carcinoids in that there is no association with hypergastrinemia, chronic atrophic gastritis, or Zollinger-Ellison syndrome. These present as large solitary lesions and are often metastatic upon diagnosis. A unique feature of type 3 is its association with an atypical carcinoid syndrome that is thought to be mediated by histamine.The treatment-including medical, endoscopic, and surgical-of gastric carcinoids is dictated by the type, size, and presence of metastasis.

Carcinoid tumor of the kidney: case report and review of the literature

Carcinoid tumors are low-grade malignant tumors that arise from neuroendocrine cells. Primary renal carcinoid tumors are extremely uncommon. They seem to be more indolent than renal cell carcinomas, although metastases to regional lymph nodes, liver, and bone have been described. The presence of metastases seems to indicate a more malignant course; however, even with metastases a patient might live for 3 or 4 years. Renal carcinoid tumors should be managed by radical or partial nephrectomy, and good outcomes have been obtained for organ-confined disease after radical excision. Conventional methods of imaging are inadequate for detecting smaller carcinoids, so somatostatin receptor scintigraphy should complement computed tomography and magnetic resonance imaging when searching for occult or metastatic disease. Close follow-up after surgery is necessary.