Compression of volume-surface integral equation matrices via Tucker decomposition for magnetic resonance applications

In this work, we propose a method for the compression of the coupling matrix in volume\hyp surface integral equation (VSIE) formulations. VSIE methods are used for electromagnetic analysis in magnetic resonance imaging (MRI) applications, for which the coupling matrix models the interactions between the coil and the body. We showed that these effects can be represented as independent interactions between remote elements in 3D tensor formats, and subsequently decomposed with the Tucker model. Our method can work in tandem with the adaptive cross approximation technique to provide fast solutions of VSIE problems. We demonstrated that our compression approaches can enable the use of VSIE matrices of prohibitive memory requirements, by allowing the effective use of modern graphical processing units (GPUs) to accelerate the arising matrix\hyp vector products. This is critical to enable numerical MRI simulations at clinical voxel resolutions in a feasible computation time. In this paper, we demonstrate that the VSIE matrix\hyp vector products needed to calculate the electromagnetic field produced by an MRI coil inside a numerical body model with $1$ mm$^3$ voxel resolution, could be performed in $\sim 33$ seconds in a GPU, after compressing the associated coupling matrix from $\sim 80$ TB to $\sim 43$ MB.Comment: 13 pages, 11 figure

Co-existence of Morgagni’s cyst with a twisted vas aberrans and “bell clapper” deformity in a 15-year-old boy: a case report

Abstract Background The testicular appendix is a residual of the paramesonephric and mesonephric duct, most commonly found close to the superior pole of the epididymis as Morgagni’s cyst. Torsion of such cysts is a common event in children, and the patient usually presents with a palpable testis with a tender mass in its upper pole. The co-existence of two or more appendices is very rare. In addition to the fact that Morgagni’s cyst was the non-twisted one and vas aberrans was, made clinical and radiological diagnosis difficult. Case presentation Our patient, a 15-year-old boy, presented with persistent pain in the right scrotum, a significant palpable mass accompanied by vomiting. Upon surgical exploration, a large dark cyst was found located on the right side of the right testicle with a 720-degree torsion. The cyst was straightened and excised along with a Morgagni’s cyst. The testis was fixed in the right hemiscrotum due to a “bell clapper” deformity that was also a finding. Conclusions Pathological findings were consistent with a twisted cyst of a testicular appendix (vas aberrans). Co-existence of two or more appendices is very rare in addition to the fact that Morgagni’s cyst was the non-twisted one. Usually and in very few cases, a second appendix is found randomly, during surgical exploration for acute scrotum due to torsion of Morgagni’s cyst