Somatostatin Receptor-PET/CT/MRI of Head and Neck Neuroendocrine Tumors

Abstract

Background and purpose: Due to its high sensitivity, somatostatin receptor-PET may detect smaller lesions and more extensive disease than contrast-enhanced MR imaging, while the superior spatial resolution of MR imaging enables lesions to be accurately localized. We compared results of somatostatin receptor-PET/MRI with those of MR imaging alone and assessed the added value of vertex-to-thigh imaging for head and neck neuroendocrine tumors.

Materials and methods: Somatostatin receptor-PET/CT was acquired as limited brain or head and neck imaging, with optional vertex-to-thigh imaging, following administration of ⁶⁴CU/⁶⁸GA DOTATATE. Somatostatin receptor-PET was fused with separately acquired contrast-enhanced MR imaging. DOTATATE activity was classified as comparable, more extensive, and/or showing additional lesions compared with MR imaging. Vertex-to-thigh findings were classified as positive or negative for metastatic disease or incidental.

Results: Thirty patients (with 13 meningiomas, 11 paragangliomas, 1 metastatic papillary thyroid carcinoma, 1 middle ear neuroendocrine adenoma, 1 external auditory canal mass, 1 pituitary carcinoma, 1 olfactory neuroblastoma, 1 orbital mass) were imaged. Five had no evidence of somatostatin receptor-positive lesions and were excluded. In 11/25, somatostatin receptor-PET/MRI and MR imaging were comparable. In 7/25, somatostatin receptor-PET/MRI showed more extensive disease, while in 9/25, somatostatin receptor-PET/MRI identified additional lesions. On vertex-to-thigh imaging, 1 of 17 patients was positive for metastatic disease, 8 of 17 were negative, and 8 of 17 demonstrated incidental findings.

Conclusions: Somatostatin receptor-PET detected additional lesions and more extensive disease than contrast-enhanced MR imaging alone, while vertex-to-thigh imaging showed a low incidence of metastatic disease. Somatostatin receptor-PET/MRI enabled superior anatomic delineation of tumor burden, while any discrepancies were readily addressed. Somatostatin receptor-PET/MRI has the potential to play an important role in presurgical and radiation therapy planning of head and neck neuroendocrine tumors.

FIG 1.

A 55-year-old man with a SSTR-avid mass centered in the right jugular fossa, which extends into the right middle ear cavity, measuring 3.7 × 3.6 × 3.5 cm, consistent with glomus jugulotympanicum paraganglioma. In this example, SSTR-PET/MRI findings are comparable with the extent of disease identified by contrast-enhanced MR imaging.

FIG 2.

A 46-year-old man with a SSTR-avid homogeneously enhancing soft-tissue mass arising from the left nasal cavity, measuring 4.0 × 1.9 × 4.1 cm in anterior-posterior by transverse by craniocaudal dimensions, consistent with biopsy-proved olfactory neuroblastoma (esthesioneuroblastoma). There was no evidence of intracranial tumor extension. In this example, SSTR-PET/MRI findings are comparable with the extent of disease identified by contrast-enhanced MR imaging.

FIG 3.

A 63-year-old woman post–right pterional craniotomy for meningioma resection with SSTR-avid recurrent meningioma arising from the right sphenoid wing and infiltrating the right orbital apex, right cavernous sinus, right sphenoid sinus, and right posterior ethmoid air cells and extending inferiorly along the right anterior temporal convexity and into the right masticator space. SSTR-positive recurrence is also noted at the right frontal craniotomy site. In this example, SSTR-PET/MRI findings were more extensive than on the basis of structural imaging because the extracranial tumor component was not identified on contrast-enhanced MR imaging.

FIG 4.

A 31-year-old woman with a vividly enhancing submandibular mass positive for neuroendocrine markers. The patient had SSTR-avid carotid body tumors, a glomus vagale tumor, and glomus jugulare tumors bilaterally. In this example, SSTR-PET/MRI findings were more extensive than on the basis of structural imaging because the right glomus jugulare tumor was not identified on contrast-enhanced MR imaging.

FIG 5.

A 69-year-old woman with a SSTR-avid recurrent meningioma in the right frontal parasagittal region and associated invasion of the calvaria and superior sagittal sinus. Incidentally noted is SSTR-positivity in the left temporomandibular joint with prominent articular/periarticular enhancement, suggestive of inflammatory/infectious arthritis. In this example, SSTR-PET/MRI findings are more extensive than on the basis of structural imaging because calvarial invasion was not identified by contrast-enhanced MR imaging of the brain.

FIG 6.

A 52-year-old woman presenting with a visual field disturbance and contrast-enhanced MR imaging demonstrating a left orbital mass concerning for orbital nerve sheath meningioma versus orbital cavernous venous malformation (cavernous hemangioma). Findings of SSTR-PET were negative and represent an orbital cavernous venous malformation. The patient was subsequently referred for surgical management.