Somatostatin analogue scintigraphy. A simple and sensitive method for the in vivo visualization of Merkel cell tumors and their metastases

Abstract

\s=b\ Background.\p=m-\Trabecular carcinomas of the skin, or Merkel cell tumors, are aggressive neoplasms that tend to occur in sun-exposed skin. These tumors frequently metastasize and, despite therapy, the number of disease-related deaths is high. Ultrastructurally and immunocytochemically, the majority of these tumors have neuroendocrine characteristics. Recently, we described the in vivo visualization of various neuroendocrine tumors after injection of a radiolabeled somatostatin analogue (octreotide). In this study, we report the results of scintigraphy with radioactive-labeled somatostatin analogues in five patients with Merkel cell tumors. Observations.\p=m-\Inall four patients in whom tumor was detected using computed tomographic scanning and ultrasound, the tumor sites were also demonstrated on octreotide scintigrams. In one patient, a tumor with a diameter that was smaller than 0.5 cm could not be detected with octreotide scintigraphy, computed tomography, or ultrasound. Using octreotide scintigraphy we found presumed tumor spots in two patients that were not evident when other techniques were used. Conclusions.\p=m-\Octreotide scintigraphy has an equal or even greater sensitivity than computed tomography and ultrasound for detecting Merkel cell tumors and their metastases. Establishing the spread of the disease in this way may ensure an optimal choice of treatment in patients with this type of tumor.

Clinical added-value of 18FDG PET in neuroendocrine-merkel cell carcinoma

“…In recent years, functional imaging methods using LM/SL and somatostatin receptor scintigraphy (SRS) have been shown to efficiently complement morphological imaging (8,11,12). This holds particularly true in stage I and II MCC patients with local and regional involvement, respectively (11).…”

“…So far, LM/SL cannot assess the full extent of the disease, especially in stage III patients with disseminated disease to nodal and visceral sites. Similarly, SRS is often of limited value for detecting metastases in organs such as liver, kidneys and spleen showing a physiological uptake of radiolabelled octreotide (12). Because the 18 FDG tracer is avidly taken up in highly aggressive malignancies including cutaneous melanoma, we investigated the potential benefit of metabolic imaging to detect 18 FDG-avid sites from MCC.…”

Recent advances in radiological and radionuclide imaging and therapy of neuroendocrine tumours

“…SS analogues bind with high affinity to SS receptor subtypes 2 and 5 which are found in a large variety of NETs, adenocarcinomas, inflammatory and immune cells (18,39). The most commonly-used SS analogue, octreotide, was initially conjugated with DTPA (diethylene-triamine-penta-acetic acid), but more recently to DOTA (1,4,7,10-tetraazacyclododecane-1,4,7, 10-tetra-acetic acid) as a way of coupling SS analogues with various radioisotopes, mainly 111 In (21,26,40). Scintigraphy with 111 In-octreotide is superior to 111 In-lanreotide and has a detection rate of 67 -100% for all NETs; it can therefore be used for the diagnosis, staging and follow-up of patients with NETs (9,41,42).…”

“…Scintigraphy with 111 In-octreotide is superior to 111 In-lanreotide and has a detection rate of 67 -100% for all NETs; it can therefore be used for the diagnosis, staging and follow-up of patients with NETs (9,41,42). 111 In-DTPA-Tyr 3 -octreotate, a newly synthesized SS analogue, demonstrated higher tumour uptake than 111 In-DTPA-Tyr 3 -octreotide whereas kidney uptake remained similar (21,43,44). More recently, 68 Ga coupled to octreotide or 64 Cu-TETA-octreotide have been used as tracers for PET imaging, and have demonstrated more lesions than 111 Inoctreotide in patients with NETs (45,46).…”

Charakterisierung und Kultivierung eines Merkel-Zell-Karzinoms

“…Der von uns hier beschriebene Fall einer 86jäh-rigen Frau mit dem Primärtumor im Gesicht bei auch sonst bestehender aktinischer Schädigung der Haut stellt die klassische Präsentation dieses Krankheitsbildes dar. Die Somatostatinanreicherung in der Szintigraphie ist ebenfalls typisch [16]. Diese Anreicherung und die Tatsa che, dass der Tumor dem APUD-Zellsystem zuzurechnen ist, rechtfertigt einen Therapieversuch mit Somatostatin.…”