131I-6β-iodomethyl-19-norcholesterol SPECT/CT for primary aldosteronism patients with inconclusive adrenal venous sampling and CT results

Abstract

The 2 main causes of primary aldosteronism(PA) are aldosteroneproducing adenoma (APA) and idiopathic adrenal hyperplasia (IAH). Dexamethasone- suppression 131I-6β-iodomethyl-19-norcholesterol (NP-59) adrenal scintigraphy can assess the functioning of the adrenal cortex. This study evaluated the diagnostic usefulness of NP-59 SPECT/CT in differentiating APA from IAH and in predicting postadrenalectomy clinical outcome for PA patients who had inconclusive adrenal venous sampling (AVS) and CT results. Methods:Weretrospectively reviewed the 31 adrenal lesions of 27 patients (age range, 33-71 y; mean age ± SD, 50.4 ± 10.9 y) who had been clinically confirmed (by saline infusion and captopril tests) to have PA, had inconclusive CT and AVS test results, and had undergone NP-59 imaging before adrenalectomy. The accuracy of NP-59 imaging was determined by comparison with histopathologic findings. Results: NP-59 SPECT/CT gave us 18 true-positive, 3 false-positive, 6 true-negative, and 4 false-negative results. Compared with planar imaging, SPECT/CT significantly improved diagnostic accuracy and prognostic predicting ability (P = 0.0390 and P = 0.0141, respectively). The NP-59 results were negative for 7 of the 23 patients with unilateral adrenal lesions, and none of these 7 patients had shown postsurgical clinical improvement. Conclusion: NP-59 SPECT/CT is an effective imaging tool for differentiating APA from IAH in PA patients whose CT and AVS results are inconclusive. Our results suggest that patients with presurgically negative NP-59 results should be treated medically and that noninvasive NP-59 SPECT/CT may be suited for use as the first lateralization modality after CT in patients with clinically confirmed PA. Copyright © 2009 by the Society of Nuclear Medicine, Inc.