Cushing syndrome, a fatal disease, is suspected in many thousands of patients each year, but confirmed in only a fraction of these. This project seeks to identify accurately which patients have Cushing syndrome, to define the etiology of their disease and to treat it optimally. We evaluated the utility of magnetic resonance imaging (MRI) for the identification of Cushing's disease. We hypothesized that the superior soft tissue contrast and thinner sections obtained with Spoiled Gradient Recalled Acquisition in the Steady State (SPGR) would improve tumor detection compared to the standard T1-weighted spin echo (SE) technique. We compared the performance of SE and SPGR MRI in 50 patients with surgically confirmed Cushing?s disease. Compared to SE for the detection of tumor, SPGR had superior sensitivity (80% vs. 49%) but a higher false positive rate (2 vs. 4%). Based on these data, we recommend the addition of SPGR to SE sequences to improve the MRI detection of ACTH-secreting pituitary tumors. We reported on an unusual cause of ectopic ACTH secretion related to the presence of an esthesioneuroblastoma (ENB) in a 36-year-old Caucasian man presenting with Cushing's syndrome. After initial biochemical studies suggestive of ectopic Cushing's syndrome, CT of the chest and abdomen revealed multiple cavitated pulmonary lesions, an ischiorectal mass, and bilateral adrenal hyperplasia. MRI of the pituitary gland revealed normal findings. Both PET scanning with [18 F]-flurodeoxyglucose (FDG) and somatostatin receptor scintigraphy with 111 indium-penetetreotide (Octreoscan) revealed strong tracer uptake in the ethmoid region. CT and MRI of the sinuses and brain subsequently localized a 5-cm mass in the ethmoid sinuses with intracranial extension. On biopsy, pathology results were consistent with a diagnosis of ENB, and immunohistochemical analysis revealed that tumor cells were strongly positive for ACTH, synaptophysin, and S-100, providing definitive diagnosis of ACTH-producing ENB. Hypercortisolemia was initially controlled by metyrapone, then by external beam radiation therapy (RT). This case illustrated the usefulness of nuclear imaging in the diagnosis of ENB, and the importance of prompt control of hypercortisolemia in Cushing's syndrome. We investigated the utility of somatostatin analogs for the treatment of Cushing's syndrome (CS) due to ectopic ACTH secretion (EAS). This condition has a high morbidity and mortality, because of the underlying tumor and the sequelae of severe hypercortisolemia. Therefore, rapid treatment of ectopic CS is mandatory. Scintigraphy shows that up to 80% of ectopic ACTH-producing tumors have somatostatin receptors. While this suggests that somatostatin analogs may reduce ACTH production and treat patients with EAS, the therapeutic role of these agents is still evolving. Here we demonstrate the spectrum of responses to octreotide therapy in 3 patients with EAS. Diagnostic imaging with the 111In-pentetreotide scan did not predict the therapeutic response to octreotide. Two patients with positive somatostatin receptor scintigraphy failed to respond to octreotide, while one with a negative scan reached eucortisolemia on a maintenance dose of 75 microg octreotide twice daily or octreotide LAR 30 mg per month. We conclude that octreotide is not a first line agent to control hypercortisolemia but may be a useful agent when other inhibitors of steroidogenesis fail or parenteral administration is required. Before therapy an octreotide challenge test may predict therapeutic response. Cortisol levels should be monitored regularly on somatostatin analog therapy, because of its unpredictable long-term pharmacodynamic profile. We evaluated the utility of jugular vein sampling (JVS) for the differential diagnosis of ACTH-dependent Cushing's syndrome. Bilateral sampling of the inferior petrosal sinuses (IPSS) to distinguish Cushing's disease from the ectopic ACTH syndrome is accurate but risky and technically difficult. JVS is simpler and presumably safer. To compare jugular and petrosal sinus venous sampling for distinguishing Cushing's disease from ectopic ACTH syndrome, we studied 74 patients with surgically proven Cushing's disease, 11 with surgically confirmed, and three with occult ectopic ACTH secretion. Patients underwent JVS and IPSS with administration of CRH on separate days. Ratios of central-to-peripheral ACTH in venous samples were calculated. At 100% specificity, IPSS correctly identified 61 of 65 patients with Cushing's disease [sensitivity, 94%; confidence interval (CI), 84-98%]. When patients with abnormal venous drainage were excluded, sensitivity was 98% (CI, 90-100%). JVS had a sensitivity of 83% (CI, 71-91%) at 100% specificity. Receiver operated characteristics plot areas under the curve were similar (0.968 +/- 0.020 and 0.974 +/- 0.016, area under the curve +/- se, JVS vs. IPSS). Although petrosal sampling had better diagnostic accuracy, CIs overlapped (95% CI, 90-100% vs. 86% CI, 78-94%). Centers with limited sampling experience may choose to use the simpler JVS and refer patients for IPSS when the results are negative. We evaluated the role of nuclear medicine and [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (FDG-PET) for the detection of tumors secreting ACTH ectopically. Conventional imaging modalities cannot localize the source of ACTH in 30-50% of patients with Cushing's syndrome caused by ectopic ACTH secretion. We prospectively evaluated whether FDG-PET or [(111)In]-diethylenetriaminepentaacetate-D-Phe-pentetreotide (OCT) at higher than standard doses of radionuclide (18 mCi; H-OCT), can detect these tumors. Seventeen patients with presumed ectopic ACTH secretion based on inferior petrosal sinus sampling results underwent routine anatomical imaging studies [computed tomography (CT) and magnetic resonance imaging (MRI)] and OCT scintigraphy with 6 mCi (L-OCT). Research studies included FDG-PET in all patients and H-OCT if L-OCT was negative. ACTH-secreting tumors were localized in 13 patients and were occult in four. Nine of 17 CT, six of 16 MRI, six of 17 FDG-PET, eight of 17 L-OCT, and one of nine H-OCT studies were true positives. The sensitivity of CT and combined H- and L-OCT scintigraphy was higher (both 53%; 95% confidence interval, 29-76%) than that of MRI (37%; 95% confidence interval, 16-64%) or FDG-PET (35%; 95% confidence interval, 15-61%). FDG-PET did not detect tumors that were occult on CT/MRI. L-OCT was a useful complementary modality to CT and MRI. As H-OCT identified a tumor in one patient with otherwise negative imaging, it should be considered only when other imaging modalities fail to localize the ACTH-secreting tumor in patients with EAS