19-iodocholesterol and Pheochromocytoma

In the setting of adrenal incidentaloma, nuclear medicine evaluation is only indicated after biological and imaging work-up has been completed. MIBG scintigraphy is helpful to characterize pheochromocytomas. In lesions without MIBG uptake, 18F FDG or 18F DOPA PET can be considered to characterize chromaffin cell tumours. To characterize lesions of the adrenal cortex, iodocholesterol scintigraphy is performed to confirm the origin of the adenoma and the benign or malignant nature of the lesion since benign adenomas show tracer uptake and malignant lesions show no tracer uptake. 18F FDG PET only characterizes the lesion as benign or malignant.

Topics: 19-Iodocholesterol; 3-Iodobenzylguanidine; Adenoma; Adrenal Cortex Neoplasms; Adrenal Gland Neoplasms; Adult; Dihydroxyphenylalanine; Female; Fluorine Radioisotopes; Fluorodeoxyglucose F18; Humans; Incidental Findings; Pheochromocytoma; Positron-Emission Tomography; Radiopharmaceuticals

In patients with non-hypersecreting adrenal masses, tumor characterization is clinically relevant to establish the appropriate treatment planning. The aim of this study was to comparatively characterize such adrenal lesions using MR and radionuclide techniques.. Thirty patients with non-hypersecreting unilateral adrenal tumors underwent both MR and adrenal scintigraphy. MR was performed using SE T1- (pre- and post-gadolinium DTPA) and T2-weighted images as well as in- and out-phase chemical-shift imaging (CSI). MR qualitative and quantitative (signal intensity ratios) evaluation was performed. Radionuclide studies consisted of iodine-131 nor-cholesterol (n=20), iodine-131 MIBG (n=15) and fluorine-18 FDG PET (n=11) scans. Histology (n=16), biopsy (n=3) or clinical-imaging follow-up (n=11) demomstrated 13 adenomas, 3 cysts, 2 myelolipomas, 4 pheochromocytomas (pheos), 4 carcinomas, 1 sarcoma and 3 metastases. Comparative imaging analysis was focused on adenomas, pheos and malignant tumors.. Qualitative MR evaluation showed: signal T2-hyperintensity in 46% of adenomas and in 100% of pheos and malignant tumors, no gadolinium enhancement in 92% of adenomas and definite signal intensity loss on CSI in 100% of such tumor lesions, gadolinium enhancement in 100% of pheos and in 63% of malignancies and no absolute change of signal intensity on CSI in 100% of both pheos and malignancies. Quantitative MR analysis demonstrated: significantly higher signal T2-hyperintensity of pheos compared to adenomas and malignancies as well as significantly higher enhancement after gadolinium in pheos compared to adenomas and malignancies (p<0.03). Radionuclide studies showed significantly increased nor-cholesterol uptake only in adenomas (n=13), significant MIBG accumulation only in pheos (n=4) and FDG activity only in malignant adrenal lesions (n=8).. MR techniques may provide some presumptive criteria to characterize non-hypersecreting adrenal masses, such as no gadolinium enhancement and definite signal intensity loss on CSI in adenomas or quantitatively measured T2-hyperintensity and gadolinium enhancement in pheos. On the other hand, radionuclide modalities offer more specific findings in this setting since nor-cholesterol and MIBG scans are respectively able to reveal benign tumors such as adenoma and pheochromocytoma, while FDG imaging allows identification of malignant adrenal lesions. Adrenal scintigraphy is recommended in those patients, when MR images are uncertain or inconclusive.

Topics: 19-Iodocholesterol; 3-Iodobenzylguanidine; Adenoma; Adrenal Gland Neoplasms; Female; Fluorodeoxyglucose F18; Humans; Iodine Radioisotopes; Magnetic Resonance Imaging; Male; Middle Aged; Pheochromocytoma; Radionuclide Imaging; Radiopharmaceuticals; Reproducibility of Results; Sensitivity and Specificity

The aim of this retrospective study was to evaluate the diagnostic accuracy of nor-cholesterol and meta-iodobenzylguanidine radionuclide imaging in two separate groups of patients with adrenal tumours to characterize lesions as adenoma or pheochromocytoma. We studied 75 patients (22 male and 53 female, mean age 47 +/- 15 years) with hypersecreting (n = 32) or non-hypersecreting (n = 43) unilateral adrenal tumours detected by computerized tomography or magnetic resonance scans. 131I nor-cholesterol adrenal scintigraphy was performed in 41 patients. Meta-[131I]iodobenzylguanidine (131I-MIBG) imaging was acquired in the other 34 patients. Pathology examinations (n = 58) or computerized tomography follow-up studies (n = 17) were obtained. Adrenal lesions were represented by 44 adenomas, four cysts, one myelolipoma, one pseudotumour, one ganglioneuroma, 16 pheochromocytomas, three carcinomas, four metastases and one sarcoma. Radionuclide studies were qualitatively evaluated and the corresponding results were classified as true positive, true negative, false positive and false negative. Diagnostic sensitivity, specificity and accuracy as well as positive and negative predictive values were calculated. The diagnostic values of nor-cholesterol scintigraphy in identifying adrenal adenomas were sensitivity 100%, specificity 71%, accuracy 95%, positive predictive value 94% and negative predictive value 100%; of note, two false positive cases were observed represented by a pheochromocytoma and a myelolipoma. The diagnostic values of MIBG scintigraphy in recognizing pheochromocytoma were sensitivity 100%, specificity 95%, accuracy 97%, positive predictive value 94% and negative predictive value 100%; only one false positive case occurred consisting of a carcinoma. It is concluded that, in the large majority of cases, adrenal scintigraphy using nor-cholesterol or MIBG is able to characterize specific lesions such as adenoma and pheochromocytoma, respectively. These findings show relevant clinical impact, particularly in patients with non-hypersecreting adrenal lasions. Radiotracer selection depends on clinical patient history and department availability; since benign adenomas are the most common cause of non-hypersecreting tumours, nor-cholesterol should be the first choice followed by MIBG if nor-cholesterol shows normal images. However, rare as well as unusual findings may be observed; nor-cholesterol uptake may occasionally be also found in non-adenoma tumours such

Topics: 19-Iodocholesterol; 3-Iodobenzylguanidine; Adenoma; Adrenal Gland Neoplasms; Adult; Aged; Female; Humans; Iodine Radioisotopes; Magnetic Resonance Imaging; Male; Middle Aged; Pheochromocytoma; Radionuclide Imaging; Radiopharmaceuticals; Retrospective Studies; Tomography, X-Ray Computed

We reviewed the findings of adrenocortical scintigraphy with 131I-6-beta-iodomethyl-19-norcholesterol (NCL-6-131I) of 39 patients to clarify its role in the evaluation of unilateral adrenal or juxtaadrenal masses incidentally discovered by CT, ultrasonography or plain radiography. Twenty-seven benign adrenal masses showed various scintigraphic findings (hot nodule: 12 silent adenomas, warm nodule: one solid mass, normal appearance: one cyst and 2 solid masses, diffuse decrease: each one; solid mass, myelolipoma, ganglioneuroma and calcified adrenal and partial or complete defect: each one; solid mass, myelolipoma and ganglioneuroma and 2 cysts and 2 pheochromocytomas); while a partial or complete defect was shown in a nonfunctioning carcinoma and 3 metastases and a complete defect or inhomogeneous uptake without opposite adrenal visualization was shown in 2 patients with cortisol-producing carcinoma. Therefore a hot nodule and an inhomogeneous uptake or complete defect with nonvisualization of the opposite adrenal are specific to a benign tumor and a cortisol-producing carcinoma, respectively. The impaired tumor uptake of NCL-6-131I is a nonspecific finding. The scintigraphic findings of juxtaadrenal masses were normal in 4 and deviated adrenals in 2. Thus adrenocortical scintigraphy can identify silent adenomas and cortisol-producing carcinomas among the adrenal masses and may help to differentiate juxtaadrenal from adrenal masses.

Topics: 19-Iodocholesterol; Adenoma; Adrenal Gland Neoplasms; Adrenocortical Adenoma; Adult; Carcinoma, Renal Cell; Female; Ganglioneuroma; Humans; Male; Middle Aged; Myelolipoma; Neurilemmoma; Pheochromocytoma; Radionuclide Imaging; Tomography, X-Ray Computed; Ultrasonography

The exact localization of adrenal lesions can be achieved by noninvasive procedures. Whereas radiological methods reflect morphological changes, scintigraphy of adrenal cortex and medulla depends on function. - Radiolabeled 6 beta-methyl-19-norcholesterol is used for adrenocortical scintigraphy in primary aldosteronism, Cushing's syndrome and hyperandrogenism. By dexamethasone suppression a correct classification of adrenocortical lesions by scintigraphy can be observed in about 89% with a specificity of 86%. 123-I- and 131-I-metaiodobenzylguanidine is used for specific scintigraphy of the adrenal medulla. This method is a safe and reliable method for localization of adrenal and extraadrenal pheochromocytomas.

Topics: 19-Iodocholesterol; 3-Iodobenzylguanidine; Adrenal Gland Diseases; Adrenal Gland Neoplasms; Cholesterol; Cushing Syndrome; Dexamethasone; Humans; Hyperaldosteronism; Iodobenzenes; Pheochromocytoma; Radionuclide Imaging; Selenium; Succimer; Technetium; Technetium Tc 99m Dimercaptosuccinic Acid

Topics: 19-Iodocholesterol; Adrenal Gland Neoplasms; Adult; Cholesterol; Humans; Iodine Radioisotopes; Male; Pheochromocytoma; Radionuclide Imaging; Ultrasonography

Topics: 19-Iodocholesterol; Adenoma; Adrenal Gland Neoplasms; Adult; Child; Cholesterol; Female; Ganglioneuroma; Humans; Iodine Radioisotopes; Male; Middle Aged; Paraganglioma, Extra-Adrenal; Pheochromocytoma; Radionuclide Imaging

Topics: 19-Iodocholesterol; Adrenal Gland Neoplasms; Adrenal Glands; Adult; Aged; Animals; Cushing Syndrome; Female; Humans; Hyperaldosteronism; Iodine Radioisotopes; Male; Middle Aged; Pheochromocytoma; Rabbits; Radionuclide Imaging