Diagnostic value of whole-body MRI with diffusion-weighted sequence for detection of peritoneal metastases in colorectal malignancy

Objective：To assess the diagnostic accuracy of whole-body MRI using diffusion-weighted sequence（WB-DWI）to determine the peritoneal cancer index（PCI）in correlation with surgical and histopathological findings.Methods：Twenty-seven patients underwent preoperative WB-MRI,followed by cytoreductive surgery for primary tumors of the appendix（n=15）,colorectum（n=12）,and associated peritoneal disease.A total of 351 regions were retrospectively reviewed.The sensitivity,specificity,and accuracy were calculated at 13 anatomical sites.The WB-DWI PCI and PCI type were compared with surgical and histopathological findings.Results：No statistical difference was found between the WB-DWI PCI and surgical PCI（P=0.574）.WB-DWI correctly predicted the PCI type in 24 of 27 patients with high accuracy（88.9%）,including 10 of 10 patients with small-volume tumor,12 of 14 with moderate-volume tumor,and 2 of 3 with large-volume tumor.WB-DWI correctly depicted tumors in 163 of 203 regions,with 40false-negative and 23 false-positive regions.The overall sensitivity,specificity,and accuracy of WB-DWI for the detection of peritoneal tumors were 80.3%,84.5%,and 82.1%,respectively.For lesions＆lt;0.5 cm in diameter,WB-DWI demonstrated good sensitivity（69.4%）.Conclusions：WB-DWI accurately predicted PCI before surgery in patients undergoing evaluation for cytoreductive surgery.

Closed form algorithm of double-satellite TDOA+AOA localization based on WGS-84 model

In this paper,we consider the double-satellite localization under the earth ellipsoid model of the Wideband Geodetic System(WGS-84)using the Time Difference of Arrival(TDOA)and the Angle-of-Arrival(AOA).Several closed-form solution algorithms via the pseudolinearization of the measurement equations are presented to efficiently estimate the location.These algorithms include the Weighted Least Squares(WLS),the Constrained Total Least Squares(CTLS),and the Taylor-Series Iteration(TSI).Performance comparison of the proposed methods with the Cramér-Rao Lower Bound(CRLB)in the simulation is shown to demonstrate that the proposed algorithms are feasible and have stable performance.