(18)F-FDG PET-CT in detecting the primary tumor in patients with metastatic cancers of unknown primary origin / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the value of (18)F-FDG PET-CT in detecting the primary tumor in patients with metastatic cancers of unknown primary origin.</p><p><b>METHODS</b>Sixty-seven patients with metastatic cancers of unknown primary origin after extensive conventional diagnostic work-up were enrolled into this study. (18)F-FDG PET-CT scans were performed at approximately 60 minutes after the intravenous injection of 7.4 MBq (18)F-FDG/kg, then delayed imaging scans was done at approximately 180 minutes for detecting the primary focus. The standardized uptake value (SUV) >or= 2.5 on standard PET/CT imaging was considered as positive. Ten percent increase of retention index (RI) was also regarded as positive. The correlation between (18)F-FDG PET-CT results and histopathological and clinical findings were analyzed, and the SUV of detected primary focus and that of metastatic cancers were compared.</p><p><b>RESULTS</b>Of the 67 patients, the primary tumors were identified in 39 (53.7%) by (18)F-FDG PET-CT, and 36 of them were confirmed by pathology or follow-up. Thirteen distant metastases and seventeen lymphatic metastases were newly discovered by whole body (18)F-FDG PET-CT imaging. The SUV of metastatic tumors was significantly lower than that of primary tumors (t = 3.470,P = 0.001) and closely correlated with that of the primary tumors (r = 0.738, P = 0.000).</p><p><b>CONCLUSION</b>(18)F-FDG PET-CT is not only valuable in identifying the unknown primary tumor in patients with metastatic carcinoma, but can also be used to reveal the biological characteristics of the tumors by functional imaging.</p>

Significance of dual-time-point 18F-FDG PET imaging in evaluation of hilar and mediastinal lymph node metastasis in non-small-cell lung cancer / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the diagnostic value of dual-time-point 18F-FDG PET-CT imaging in detecting hilar and mediastinal lymph node metastasis in non-small-cell lung cancer (NSCLC).</p><p><b>METHODS</b>Forty-six patients with NSCLC underwent standard whole body single-time 18F-FDG PET-CT scans and a delayed imaging for the thorax alone before surgery, meanwhile, the standard uptake value (SUV) and retention index (RI) were calculated.</p><p><b>RESULTS</b>A total number of 584 lymph nodes were excised in the 46 patients. Of these, 134 metastatic lymph nodes were pathologically confirmed in 31 patients. There were 189 lymph nodes detected and suspected to be metastatic by standard single-time 18 F-FDG PET-CT imaging, and 161 by dual-time-point imaging. Therefore, the sensitivity, specificity, diagnostic accuracy, positive predictive value and negative predictive value in the detection of hilar and mediastinal lymph node metastasis were 87.3%, 84.0%, 84.8%, 61.9% and 95.7% by standard single-time 18F-FDG PET-CT imaging, versus 94.8%, 92.2%, 92.8%, 78.9% and 98.1%, respectively, by dual-time-point imaging. There was a statistically significant difference in the detection of lymph node metastasis between the standard single-time imaging and dual-time-point 18F-FDG PET-CT imaging.</p><p><b>CONCLUSION</b>Dual-time-point 18F-FDG PET-CT imaging is more sensitive, specific and accurate than standard single-time 18F-FDG PET-CT imaging in the detection of hilar and mediastinal lymph node metastasis, and may provide more information for diagnosis, staging and treatment of non-small cell lung cancer.</p>