Comparison of non-electrophoresis grade with electrophoresis grade BIS in NIPAM polymer gel preparation

Introduction: The main objective of this study was to investigate the possibility of replacing electrophoresis cross-linker with non-electrophoresis N, N'-methylenebisacrylamide (BIS) in N-isopropyl acrylamide (NIPAM) polymer gel and its possible effect on dose response. Methods: NIPAM polymer gel was prepared from non-electrophoresis grade BIS and the relaxation rate (R-2) was measured by MR imaging after exposing the gel to gamma radiation from Co-60 source. To compare the response of this gel with the one that contains electrophoresis grade BIS, two sets of NIPAM gel were prepared using electrophoresis and non-electrophoresis BIS and irradiated to different gamma doses. Results: It was found that the dose-response of NIPAM gel made from the non-electrophoresis grade BIS is coincident with that of electrophoresis grade BIS. Conclusion: Taken all, it can be concluded that the non-electrophoresis grade BIS not only is a suitable alternative for the electrophoresis grade BIS but also reduces the cost of gel due to its lower price

Diagnostic accuracy of twinkling artifact sign seen in color doppler ultrasonography in detecting microlithiasis of kidney

Background: Ultrasonography (US) is a safe and cost-efficient modality which is used to assess patients with urinary tract lithiasis. Objectives: In this study, we aimed to evaluate the accuracy of the twinkling artifact of color Doppler sonography in detecting renal stones smaller than 4 mm in diameter. Methods: Of all patients referring to a tertiary medical center with a probable diagnosis of urolithiasis during April 2019 to Septem-ber 2019, 99 patients with a renal stone smaller than 4 mm in non-contrast computed tomography (CT) scan entered our study. Both gray scale and color Doppler US were performed to assess the presence of any renal stones, the accompanying posterior shadowing, and the twinkling artifact for all patients. Results: Of 99 patients with confirmed renal stone on non-contrast CT scan, 91 patients had an echogenic focus on grayscale (sensi-tivity = 91.9), 70 patients had posterior shadowing sign (sensitivity = 70.7), and 76 patients had twinkling artifact on color Doppler US. The sensitivity, specificity, positive predictive value, and negative predictive value of this imaging finding for detecting renal stones smaller than 4 mm were 76.8, 100, 100, and 32.4, respectively. Conclusions: Our study revealed that twinkling artifact on color Doppler US is a reliable sign for detecting renal stones smaller than 4 mm. However, the sensitivity of this sign could be increased in combination with gray scale findings (echogenic focus and posterior shadowing). © 2020, Author(s)