MIR Teaching file case mb007

Case Author(s): Feiyu Xue, M.D., Ph.D. and Jerold W. Wallis, M.D. , 6/28/04 . Rating: #D3, #Q3

Diagnosis: Brown fat uptake on MIBG scintigraphy

Brief history:

3-year-old boy with history of neuroblastoma

Images:

Whole body MIBG scintigraphy, 5/5/04

View main image(mb) in a separate image viewer

Full history/Diagnosis is available below

Diagnosis: Brown fat uptake on MIBG scintigraphy

Full history:

3-year-old boy with history of neuroblastoma, treated with chemotherapy, radiation chemotherapy, and stem cell transplant. He presents for follow-up evaluation.

Radiopharmaceutical:

2.1 mCi MIBG i.v.

Findings:

There is no evidence of recurrent or metastatic disease. Normal uptake is seen in salivary glands, heart and liver. Increased activity in the region of upper chest laterlly is seen; this is a normal variant, likely due to brown fat.

Discussion:

The increased activity in the region upper chest laterally is due to brown fat. Similar activity is seen on an earlier study on 10/29/03 (see follow up image). Brown fat plays an important role in cold-induced and diet-induced thermogenesis. Children have abundant brown fat in the region of neck and upper chest. The thermogenesis of brown fat is regulated mainly by the sympathetic nervous system (via ß-adrenergic receptors). An animal study demonstrate localization of tracer in the brown fat tissue in mice after I.V. injection of I-125 MIBG (1). Increased activity seen on MIBG scan is thought due to binding of tracer to ß-adrenergic receptors in brown fat (2).

References: (1) Okuyama C, Sakane N, Yoshida T, Shima K, Kurosawa H, Kumamoto K, Ushijima Y, Nishimura T. (123)I- or (125)I-metaiodobenzylguanidine visualization of brown adipose tissue. J Nucl Med. 2002 Sep;43(9):1234-40.

(2) Okuyama C, Ushijima Y, Kubota T, Yoshida T, Nakai T, Kobayashi K, Nishimura T. 123I-Metaiodobenzylguanidine uptake in the nape of the neck of children: likely visualization of brown adipose tissue. J Nucl Med. 2003 Sep;44(9):1421-5.

View followup image(mb). Whole body MIBG scintigraphy, 10/29/03

Major teaching point(s):

Be aware that activity in anterior neck and upper chest in brown fat can be normal findings on MIBG scintigraphy.

ACR Codes and Keywords:

General ACR code: 88

References and General Discussion of MIBG Scintigraphy (Anatomic field:Genitourinary System, Category:Misc)

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Case number: mb007