CASE OF THE WEEK – “Hybrid SPECT-CT somatostatin-receptor scintigraphy with 99mTc-Tektrotyd in follow up of post-operative neuroendocrine tumor of 3rd part of duodenum (unusual site) with liver metastases” by Dr Shekhar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

CASE OF THE WEEK – “Hybrid SPECT-CT somatostatin-receptor scintigraphy with 99mTc-Tektrotyd in follow up of post-operative neuroendocrine tumor of 3rd part of duodenum (unusual site) with liver metastases” by Dr Shekhar Shikare, HOD & Consultant, Nuclear Medicine, NMC Royal Hospital Sharjah

Neuroendocrine neoplasms (NENs) originate from neuroendocrine (enterochromaffin) cells located in neuroendocrine tissue which are dispersed throughout the body, although are usually located in endocrine glands and in gastrointestinal and bronchopulmonary systems. Most of NETs are sporadic but about 20% of NENs occur in the context of a genetic syndrome like multiple endocrine neoplasia types 1 and 2, and von Hippel-Lindau and neurofibromatosis type 1 and pheochromocytoma /paraganglioma syndromes. Neuroendocrine neoplasm group cover GEP-NETs (gastro-entero-pancreatic neuroendocrine tumors) and lung NENs as well as other neoplasms originating from a neurocranial cells such as pheochromocytoma, paraganglioma, neuroblastoma and medullary thyroid cancer.

Detection of neuroendocrine neoplasms (NENs) and monitoring of their response to therapy is still challenging due to huge heterogeneity of that group of tumors. NENs visualization is mainly based on molecular imaging while in the past it was relied on less effective structural imaging including CT and MRI. Molecular imaging techniques in combination with structural imaging (hybrid imaging), especially in patients with well-differentiated NENs.

In addition to morphological provide the functional information about tumor which benefits in a more accurate patient management, including more sensitive visualization of primary tumors, more precise staging and better therapy follow-up.

Overexpression of somatostatin receptors (SSTR) on NENs’ cell membrane was a basis for development of somatostatin receptor scintigraphy (SRS) using single photon emission tomography SPECT, which is today a well-established standard in molecular imaging of NENs, and further imaging improvement in the field of positron emission tomography (PET). Use of hybrid imaging (SPECT/CT, PET/CT) increased sensitivity of examination, mainly resulting in better detection of small lesions.

Case

48 years old gentleman is case of Neuroendocrine tumor- Duodenum 3rd/4th part with mesenteric nodes and liver metastases.
Chromogranin levels 1986 ng/ml (0.0-101.8) (March 2020),

March 20-F18 FDG PET-CT showed hypermetabolic mass in 3rd part of duodenum with hypermetabolic liver metastasis in segment VI and VII.

Treated with injection sand statin LAR * 3 cycles with one month gap (march to June 2020), chromogranin levels A 106.4
July 20- Preoperative Ga68 Dotatate PET CT

Metabolic progression of D3 lesion (SUV 16.2 from SUV 5.17) and two hypermetabolic (moderately increased uptakes) liver metastases in segment VI (SUV 6.96 from 3.04) and VII (SUV 8.94 from 3.52)

July 20-Duodenostostomy (segmental resection + duodeno- jujenal anastomosis + liver metastasesctomy. Intraoperatively multiple military metastasis deposit all over the surface., D4 involvement margin free.

Received 4 cycles of adjuvant chemotherapy (Inj cisplatin etoposide (Aug 20 to March 21.

Nov.2020 CT scan abdomen shows no residual disease.

Feb 2021- chromogranin A levels 322 and on injection sand statin LAR 20 mg deep I/m 3 cycles monthly

Refereed for 99mTc-TEKTROTYED WHOLE BODY AND SPECT-CT OCTREOSCAN (SOMATOSTATIN RECEPTOR IMAGING)} TO LOOK FOR THE RESIDUAL DISEASE AND STATUS OF LIVER METASTASES.

99mTc-TEKTROTYD (SOMATOSTATIN RECEPTOR IMAGING)}

WHOLE BODY IMAGES ARE OBTAINED AT 2.0 HRS, 5.0 HRS AND SPECT- CT FUSED IMAGES AT 5.0 HRS

It shows

a) Two small focal areas of varying in size and varying in tracer uptake intensity seen in 3rd part of duodenum.

b) Multiple small focal areas of varying tracer uptake intensity seen in liver segments (II, IV, VI, VII, VIII)

Better appreciated on SPECT-CT fused images)

There is NO obvious focal areas of any abnormal tracer accumulation seen elsewhere on whole body and SPECT-CT fused images.

SOMATOSTATIN RECEPTOR EXPRESSION (SRS) LESIONS ARE SEEN IN 3RD PART OF THE DUODENUM AND MULTIPLE LIVER SEGMENTS.

As compared to pre-operative Ga68 Dotatate PET CT images, there is small residual tumor tissue in 3rd portion of the Duodenum and progression of liver metastasis (at least five segmental liver metastases with varying tracer uptake intensity is seen)

Figure 1 & 2

99mTc-TEKTROTYD (SOMATOSTATIN RECEPTOR) HYBRID SPECT CT IMAGES SHOWS-Two small focal areas of varying in size and varying in tracer uptake intensity seen in 3rd part of duodenum (figure1 & 2).

Figure 3 & 4

99mTc-TEKTROTYD (SOMATOSTATIN RECEPTOR) HYBRID SPECT CT IMAGES SHOWS- Multiple small focal areas of varying tracer uptake intensity seen in liver segments II, IV, VI, VII, VIII AS SHOWN IN FIGURE ( 3 to 6).

Figure 5 & 6

Discussion

Duodenal NENs (d-NENs) are rare tumors and comprise 1–3% of all duodenal neoplasms. Most of these tumors are located in the first or second part of duodenum and their frequency progressively decreases towards the distal parts of the duodenum, while 20% arise in the periampullary region. D-NENs are generally small (<2 cm) and usually confined to mucosa or submucosa but in approximately 40–60% and 10% lymph node and liver metastases respectively have been reported. The majority (90%) of d-NENs are nonfunctional but can also be associated with Zollinger–Ellison (sporadic or related to MEN1) or rarely with carcinoid syndrome.

Treatment of NENs has traditionally been mainly surgical; however, in recent decades there has been a considerable evolution of a number of nonsurgical treatments that have expanded the therapeutic options of these neoplasms. In NENs G1 or G2, surgery with an intention to cure can be considered even in the presence of liver or lymph node metastases. In patients with advanced disease, tumor debulking techniques such as hepatic artery embolization (HAE), selective internal radiotherapy (SIRT), radiofrequency ablation (RFA) and palliative hepatic cytoreductive surgery may significantly decrease the tumor burden or lead to symptomatic improvement of hormone excess states. As the majority of NENs express SSTRs, long-acting somatostatin analogs (SSAs) play an important role in the treatment of patients with NENs and may result in symptomatic, biochemical and objective responses. Systemic treatment of patients with NENs involves also chemotherapy, interferon-α and targeted agents such as the mammalian target of rapamycin (mTOR) inhibitor, or the tyrosine kinase inhibitor, sunitinib. In addition, peptide receptor radionuclide therapy (PRRT) is a plausible therapeutic option in patients with tumors expressing SSTRs, as it has demonstrated antitumor efficacy and amelioration of refractory hormone secretion syndromes. Treatment of G3 tumors is based on limited evidence and involves surgical resection and chemotherapy, or PRRTs in the case of well-differentiated tumors.