Preoperative segmental localization of colorectal carcinoma: CT colonography vs. optical colonoscopy.

BACKGROUND: Adequate preoperative segmental localization of colorectal cancer is important to indicate the right surgical treatment. Preoperative localization has become more important in the era of minimally invasive surgery. The aim of this study was to compare optical colonoscopy (OC) and CT colonography (CTC) with respect to the error rates in the segmental localization of colorectal carcinoma. METHODS: A total of 420 patients with histopathologically proven colorectal carcinoma underwent CTC between December 2006 and February 2017. 284 Of these patients underwent surgical resection and had their carcinomas located on CTC report as well as OC report and surgical report. The segmental localization error rates of OC and CTC were compared using surgery as golden standard. McNemar's test was used to evaluate the differences in error rate. RESULTS: 284 Patients with a total of 296 colorectal carcinomas were evaluated. The segmental localization error rate of CTC (39/296, 13.2%) was found to be lower than the segmental localization error rate of OC (64/296, 21.6%) (p < 0.001). Per segment analysis showed that OC had a significantly higher error rate for carcinomas located in the descending colon (60.6% vs. 21.2% [p < 0.001] and cecum(60.0% vs. 23.3% [p = 0.001]). In 9.2% of the patients (26/284), localization based on CTC would lead to a change in surgical plan. CONCLUSION: CTC has a lower localization error rate than OC, which is most relevant for tumors located in the descending colon. If there is a doubtful localization on OC, particularly in the left-sided colon, an additional CTC should be performed to choose the best surgical treatment.

Quantitative Tomography of Organic Photovoltaic Blends at the Nanoscale.

The success of semiconducting organic materials has enabled green technologies for electronics, lighting, and photovoltaics. However, when blended together, these materials have also raised novel fundamental questions with respect to electronic, optical, and thermodynamic properties. This is particularly important for organic photovoltaic cells based on the bulk heterojunction. Here, the distribution of nanoscale domains plays a crucial role depending on the specific device structure. Hence, correlation of the aforementioned properties requires 3D nanoscale imaging of materials domains, which are embedded in a multilayer device. Such visualization has so far been elusive due to lack of contrast, insufficient signal, or resolution limits. In this Letter, we introduce spectral scanning transmission electron tomography for reconstruction of entire volume plasmon spectra from rod-shaped specimens. We provide 3D structural correlations and compositional mapping at a resolution of approximately 7 nm within advanced organic photovoltaic tandem cells. Novel insights that are obtained from quantitative 3D analyses reveal that efficiency loss upon thermal annealing can be attributed to subtle, fundamental blend properties. These results are invaluable in guiding the design and optimization of future devices in plastic electronics applications and provide an empirical basis for modeling and simulation of organic solar cells.