 2. All participants must meet one of the following: i Patients diagnosed or suspected to have NET, who require 111In-pentetreotide imaging for clinical indications. ii Subjects with a high risk of NET because of familial predisposition, and also have clinical findings which require radiolabeled somatostatin imaging. iii Other somatostatin-positive tumors for which 111In -pentetreotide has been used successfully, such as adult meningiomas. iv Patients with suspected neuroendocrine tumor, unknown primary NET, metastatic NET, or other tumors, such as meningiomas, in whom the primary physician considers somatostatin imaging to be clinically indicated. v Other NET subjects, whether asymptomatic or symptomatic, sporadic or familial, such as VHL and MEN1, will also be included. 