Sibyll Goetze MD, Presenter: Nothing to Disclose

William C. Lavely MD, Abstract Co-Author: Nothing to Disclose

Harvey A. Ziessman MD, Abstract Co-Author: Nothing to Disclose

Richard Leo Wahl MD, Abstract Co-Author: Nothing to Disclose

Brown adipose tissue (BAT) has been shown to be metabolically active in some adults and can be a confounding factor on several types of nuclear scans. Previously, BAT has been visualized by F-18 FDG PET, I-123 metaiodobenzylguanidine, and Tc-99m tetrofosmin. Tc-99m methoxyisobutylisonitrile (Tc-99m MIBI) is widely used for many imaging applications. Thorough examination of a Tc-99m MIBI scan includes assessment of the visualized body to exclude tumor involvement, which may take up Tc-99m MIBI. We suspected MIBI might accumulate in BAT in patients imaged using Tc-99m MIBI and evaluated this possibility reviewing SPECT/CT images.

We retrospectively reviewed scintigrams of 111 patients (60 ± 13 years, 86 female, 25 male) who were evaluated for parathyroid adenoma from March 2004 to February 2005. SPECT-CT of the neck and chest were obtained on GE Millenium VG/Hawkeye® or Infinia® SPECT/CT systems 30 minutes and 2.5 hours after injection of 25 mCi (740 MBq) of Tc99m MIBI. SPECT-CT images were reviewed on a GE Xeleris® workstation and qualitatively assessed for uptake of the radiotracer in areas of BAT.

We detected uptake of Tc99m MIBI in BAT in 5.4% of patients: one male (age 57) and five females (age 26, 52, 57, 60, and 84). Scans which showed MIBI avid BAT were obtained in July (n=1), September (1), October (1), December (1) and January (2). BAT was localized to the supraclavicular area in 5 patients, and in the region of the atria in 1 patient, possibly representing an atrial hibernoma. MIBI uptake in BAT was seen on both early and delayed images. With fused images, BAT could clearly be distinguished from muscle, bone, myocardium, and other structures in the neck and chest.

BAT can be localized with Tc-99m MIBI and should not be confused with disease, such as abnormal uptake in lymph nodes, tumor, parathyroid adenoma, or muscle. The frequency of BAT visualization is similar to studies with F-18 FDG PET (4-7%) in adults. A higher frequency of BAT with Tc-99m tetrofosmin was reported, but might be related to the pediatric population, and the fact that no CT was obtained to ascertain that the tracer accumulation definitely is in BAT.

R.L.W.: GE Medical Systems (Commercial Grants and Honorarium); Philips (Honorarium); CPS Innovations (Honorarium); Cardinal Health (Honorarium); Nihon-Medi-Physics Corporation (Consultant); Threshold Pharmaceuticals (Consultant), National Cancer Institute (Research support)

Brown adipose tissue (BAT) has been shown to be metabolically active in some adults and can be a confounding factor on several types of nuclear scans. Previously, BAT has been visualized by F-18 FDG PET, I-123 metaiodobenzylguanidine, and Tc-99m tetrofosmin. Tc-99m methoxyisobutylisonitrile (Tc-99m MIBI) is widely used for many imaging applications. Thorough examination of a Tc-99m MIBI scan includes assessment of the visualized body to exclude tumor involvement, which may take up Tc-99m MIBI. We suspected MIBI might accumulate in BAT in patients imaged using Tc-99m MIBI and evaluated this possibility reviewing SPECT/CT images.

We retrospectively reviewed scintigrams of 111 patients (60 ± 13 years, 86 female, 25 male) who were evaluated for parathyroid adenoma from March 2004 to February 2005. SPECT-CT of the neck and chest were obtained on GE Millenium VG/Hawkeye® or Infinia® SPECT/CT systems 30 minutes and 2.5 hours after injection of 25 mCi (740 MBq) of Tc99m MIBI. SPECT-CT images were reviewed on a GE Xeleris® workstation and qualitatively assessed for uptake of the radiotracer in areas of BAT.

We detected uptake of Tc99m MIBI in BAT in 5.4% of patients: one male (age 57) and five females (age 26, 52, 57, 60, and 84). Scans which showed MIBI avid BAT were obtained in July (n=1), September (1), October (1), December (1) and January (2). BAT was localized to the supraclavicular area in 5 patients, and in the region of the atria in 1 patient, possibly representing an atrial hibernoma. MIBI uptake in BAT was seen on both early and delayed images. With fused images, BAT could clearly be distinguished from muscle, bone, myocardium, and other structures in the neck and chest.

BAT can be localized with Tc-99m MIBI and should not be confused with disease, such as abnormal uptake in lymph nodes, tumor, parathyroid adenoma, or muscle. The frequency of BAT visualization is similar to studies with F-18 FDG PET (4-7%) in adults. A higher frequency of BAT with Tc-99m tetrofosmin was reported, but might be related to the pediatric population, and the fact that no CT was obtained to ascertain that the tracer accumulation definitely is in BAT.

R.L.W.: GE Medical Systems (Commercial Grants and Honorarium); Philips (Honorarium); CPS Innovations (Honorarium); Cardinal Health (Honorarium); Nihon-Medi-Physics Corporation (Consultant); Threshold Pharmaceuticals (Consultant), National Cancer Institute (Research support)

Goetze, S, Lavely, W, Ziessman, H, Wahl, R, Visualization of Brown Adipose Tissue with Tc-99m Methoxyisobutylisonitrile on SPECT/CT.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4413167.html