Value of C-11 Methionine Whole Body PET Imaging in the Diagnosis of Skeletal Metastases | ||||
| Egyptian Journal Nuclear Medicine | ||||
| Article 5, Volume 9, Issue 9, June 2014, Page 42-54 PDF (268 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/egyjnm.2014.2564 | ||||
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| Abstract | ||||
| Introduction: There is an increasing clinical interest in imaging tumors’ protein metabolism through PET studies using radiolabeled amino acids, and one of the most commonly used tracer in this regard is C-11 methionine. The latter was recently employed successfully for diagnosis and assessment of treatment response in some tumors. The aim of the current study is to assess the value of 11 C-Methionine (MET) in the diagnosis of skeletal metastases. Patients and methods: Over approximately 12 years in our institute (1994-2006), 8041 patients performed static MET PET scans for local assessment of tumor response to carbon ion radiotherapy (CIRT) in addition to whole body (WB) images without attenuation correction. Out of these patients, 254 cancer patients had reported areas of abnormal skeletal MET uptake on WB images. Sixty studies were only included because of available follow up with conventional imaging modalities (CIM), as the reference standard, for final diagnosis of the bony lesions whether metastatic or not. All suspected skeletal areas were counted and differentiated, according to the degree of uptake whether low, moderate or intense and reported as having low, equivocal or high metastatic possibility respectively. Results: 77 bony areas of abnormal MET accumulation were reported, out of them 14 were diagnosed to be metastatic in nature (18.2%), while the remaining 63 (81.8%) diagnosed as benign osseous lesions. Low, equivocal or high metastatic possibilities were encountered in 58, 7 and 12 osseous sites respectively. Diagnosis of metastases was confirmed in 1 out of 58 (1.7%), 2 out of 7 (28.6%) and 11 out of 12 (91.7%) sites with low, equivocal and intense tracer uptake respectively. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of MET- PET- WB study in diagnosis ofosseous deposits were 78.6%, 98.4%, 91.7%, 95.4 % and 94.8% respectively when equivocal lesions are included in the low possibility category. These figures were 68.4%, 98.3%, 92.9%, 90.5% and 90.9% respectively if equivocal lesions were included in the high possibility category of being metastatic. Conclusion: MET PET WB imaging is an accurate tool in the diagnosis of skeletal metastatic lesions in various malignancies. Higher diagnostic accuracy is found when only lesions with high degree of tracer uptake are considered metastatic. | ||||
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