Influence of contrast media dose and osmolality on the diagnostic performance of contrast fractional flow reserve

Background—Contrast fractional flow reserve (cFFR) is a method for assessing functional significance of coronary stenoses, which is more accurate than resting indices and does not require adenosine. However, contrast media volume and osmolality may affect the degree of hyperemia and therefore diagnostic performance. Methods and Results—cFFR, instantaneous wave–free ratio, distal pressure/aortic pressure at rest, and FFR were measured in 763 patients from 12 centers. We compared the diagnostic performance of cFFR between patients receiving low or iso-osmolality contrast (n=574 versus 189) and low or high contrast volume (n=341 versus 422) using FFR≤0.80 as a reference standard. The sensitivity, specificity, and overall accuracy of cFFR for the low versus iso-osmolality groups were 73%, 93%, and 85% versus 87%, 90%, and 89%, and for the low versus high contrast volume groups were 69%, 99%, and 83% versus 82%, 93%, and 88%. By receiver operating characteristics (ROC) analysis, cFFR provided better diagnostic performance than resting indices regardless of contrast osmolality and volume (P<0.001 for all groups). There was no significant difference between the area under the curve of cFFR in the low- and iso-osmolality groups (0.938 versus 0.957; P=0.40) and in the low- and high-volume groups (0.939 versus 0.949; P=0.61). Multivariable logistic regression analysis showed that neither contrast osmolality nor volume affected the overall accuracy of cFFR; however, both affected the sensitivity and specificity. Conclusions—The overall accuracy of cFFR is greater than instantaneous wave–free ratio and distal pressure/aortic pressure and not significantly affected by contrast volume and osmolality. However, contrast volume and osmolality do affect the sensitivity and specificity of cFFR

Suppression of Instability on Sensing Signal of Optical Pulse Correlation Measurement in Remote Fiber Sensing

Optical fiber sensing has the potential to overcome weak points of traditional electric sensors. Many types of optical fiber sensors have been proposed according to the modulation parameter of incident light. We have proposed an optical pulse correlation sensing system that focuses on the time drift values of the propagating optical pulses to monitor the temperature- or strain-induced extension along the optical fiber in the sensing region. In this study, we consider the instability in the optical pulse correlation sensing system applied to remote monitoring over a kilometer-long distance. We introduce a method to stabilize the instability of the pulse correlation signal resulting from the time drift fluctuation along a transmission line. By using this method, we can purify the response and improve the accuracy of signals at the focused sensing regions. We also experimentally demonstrate remote temperature monitoring over a 30 km-long distance using a remote reference technique, and we estimate the resolution and the measurable span of the temperature variation as (1.1/L)∘C and (5.9×10/L)°C, respectively, where L is the length of the fiber in the sensing region

Newly Developed Fully Covered Metal Stent for Unresectable Malignant Biliary Stricture

We herein report two patients with unresectable malignant biliary stricture who underwent stenting with a newly developed fully-covered metal stent. In the first case of lower-middle bile duct cancer, a stent was placed through the stenosis. In the second case of middle bile duct stricture due to lymph node metastases from gallbladder cancer, a stent was placed in the bile duct across the stenosis. No procedure-related complications were observed. Unevenness of the outer surface and a low shortening ratio are expected to lessen the occurrence of complications characteristic of covered metal stents such as stent migration and bile duct kinking