Bekir TASDEMİR, Zeki DOSTBİL, Kemal UNAL, Sule YİLDİRİM, Ayse AKATLİ

The significance of lower extremity FDG PET/CT imaging in patients with unknown primary tumor

If a suspicious finding for primary site of an unknown primary tumor (UPT) is found in limited whole-body FDG PET/CT imaging area, imaging of lower extremities is generally not performed in routine practice. This approach may not be true. In this case, FDG PET/CT imaging was performed in patient with UPT. The limited whole-body FDG PET/CT images showed an increased FDG uptake in a thyroid nodule which was seemed to be a primary lesion at first sight. But similar FDG PET/CT findings might be observed in benign thyroid nodules. So we also acquired FDG PET/CT images of the lower extremities. Then, a mass showing increased FDG uptake was seen in the left thigh. On histopathologic examination, the thyroid nodule was found to be benign and the left thigh mass was diagnosed with a malignant (hemangiopericytoma). This case demonstrates contribution of lower extremity FDG PET/CT imaging to detection of primary site of UPTs in suspected situations.

Keywords:

Positron emission tomography, unknown primary tumor, field of view, lower extremity, hemangiopericytoma,

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Park JS, Yim JJ, Kang WJ, et al. Detection of primary sites in unknown primary tumors using FDG-PET or FDG-PET/CT. BMC Res Notes 2011;4:56
Fizazi K, Culine S. Metastatic carcinoma of unknown origin. Bull Cancer 1998;85:609-617.
Kwee TC, Basu S, Cheng G, Alavi A. FDG PET/CT in carcinoma of unknown primary. Eur J Nucl Med Mol Imaging 2010;37:635-644.
Osman MM, Chaar BT, Muzaffar R, et al. 18F-FDG PET/CT of patients with cancer: comparison of whole-body and limited whole-body technique. AJR Am J Roentgenol 2010;195:1397-1403.
Delbeke D, Coleman RE, Guiberteau MJ, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0. J Nucl Med 2006;47:885-895.
Abdelmalik AG, Alenezi S, Muzaffar R, Osman MM. The Incremental Added Value of Including the Head in (18)F-FDG PET/CT Imaging for Cancer Patients. Front Oncol 2013;3:71.
Lee HY, Lee KS, Kim BT, et al. Diagnostic efficacy of PET/CT plus brain MR imaging for detection of extrathoracic metastases in patients with lung adenocarcinoma. J Korean Med Sci 2009;24:1132-1138.
Nguyen NC, Chaar BT, Osman MM. Prevalence and patterns of soft tissue metastasis: detection with true whole-body F-18 FDG PET/CT. BMC Med Imaging 2007;7:8.
Sebro R, Mari-Aparici C, Hernandez-Pampaloni M. Value of true whole-body FDG PET/CT scanning protocol in oncology: optimization of its use based on primary diagnosis. Acta Radiol 2013;54:534-539
Bochev P, Klisarova A, Kaprelyan A, et al. Brain metastases detectability of routine whole body (18)F-FDG PET and low dose CT scanning in 2502 asymptomatic patients with solid extracranial tumors. Hell J Nucl Med 2012;15:125-129.
Kitajima K, Nakamoto Y, Okizuka H, et al. Accuracy of whole-body FDG PET/CT for detecting brain metastases from non-central nervous system tumors. Ann Nucl Med 2008;22:595-602.
Rohren EM, Provenzale JM, Barboriak DP, Coleman RE. Screening for cerebral metastases with FDG PET in patients undergoing whole-body staging of non-central nervous system malignancy. Radiology 2003;226:181-187.
Posther KE, McCall LM, Harpole DH Jr, et al. Yield of brain 18F-FDG PET in evaluating patients with potentially operable non-small cell lung cancer. J Nucl Med 2006;47:1607-1611.
Boellaard R, O'Doherty MJ, Weber WA, et al. FDG PET and PET/CT: EANM procedure guidelines for tumor PET imaging: version 1.0. Eur J Nucl Med Mol Imaging 2010;37:181-200.
ACR-SPR practice guideline for performing FDG PET/CT in oncology. American College of Radiology Web site. http://www.acr.org/~/media/71B746780F934F6D8A1BA5CCA5167EDB.pdf Accessed 06 Jan 2015.