Dual-energy CT in the assessment of mediastinal lymph nodes: comparative study of virtual non-contrast and true non-contrast images.

OBJECTIVE: To evaluate the reliability of virtual non-contrast (VNC) images reconstructed from contrast-enhanced, dual-energy scans compared with true non-contrast (TNC) images in the assessment of high CT attenuation or calcification of mediastinal lymph nodes. MATERIALS AND METHODS: A total of 112 mediastinal nodes from 45 patients who underwent non-contrast and dual-energy contrast-enhanced scans were analyzed. Node attenuation in TNC and VNC images was compared both objectively, using computed tomography (CT) attenuation, and subjectively, via visual scoring (0, attenuation ≤ the aorta; 1, > the aorta; 2, calcification). The relationship among attenuation difference between TNC and VNC images, CT attenuation in TNC images, and net contrast enhancement (NCE) was analyzed. RESULTS: CT attenuation in TNC and VNC images showed moderate agreement (intraclass correlation coefficient, 0.612). The mean absolute difference was 7.8 ± 7.6 Hounsfield unit (HU) (range, 0-36 HU), and the absolute difference was equal to or less than 10 HU in 65.2% of cases (73/112). Visual scores in TNC and VNC images showed fair agreement (κ value, 0.335). Five of 16 nodes (31.3%) which showed score 1 (n = 15) or 2 (n = 1) in TNC images demonstrated score 1 in VNC images. The TNC-VNC attenuation difference showed a moderate positive correlation with CT attenuation in TNC images (partial correlation coefficient [PCC] adjusted by NCE: 0.455) and a weak negative correlation with NCE (PCC adjusted by CT attenuation in TNC: -0.245). CONCLUSION: VNC images may be useful in the evaluation of mediastinal lymph nodes by providing additional information of high CT attenuation of nodes, although it is underestimated compared with TNC images.

Expression of the stem cell markers CD133 and nestin in pancreatic ductal adenocarcinoma and clinical relevance.

BACKGROUND: To evaluate the prognostic implication of cancer stem cell markers in pancreac ductal adenocarcinoma (PDAC), the expression of CD133 and nestin were investigated in a series of PDAC patients in relation to the survival rate. METHODS: This series included 42 cases of PDAC patients and evaluated the stem cell markers CD133 and nestin expression detected by immunohistochemistry. The presence of immunopositive tumor cells considering intensity and area was evaluated and interpreted in comparison to the patients' clinicopathological and survival data. RESULTS: Twenty eight cases (66.7%) showed high CD133 expression. The CD133 expression was mainly identified in the apical border of the tumor cell, but aberrant expression in the cytoplasmic or perinuclear location was also noted. High nestin expression in tumor cells were found in only 2 cases, but high nestin expression along perinuerial or stromal region was found in 15 cases (35.7%). There was no correlation between CD133, nestin expression and gemcitabine resistance. Statistically significant difference was found in patient survival in N stage (p=0.007), and CD133 expression (p= 0.014) in univariate analysis. Nestin expression wan not statistically significant, but it was helpful to identify the perineurial invasion. In Cox-regression hazard model stratified by age and sex for multivariable analysis, AJCC stage and CD133 were independent prognostic factors for overall survival. CONCLUSIONS: CD133 expression is upregulated in PDAC that is related to poor prognosis, and treatment targeted the CD133 positive cancer/cancer stem cells might be a promising therapeutic strategy for this patients.