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A prospective study was undertaken to assess the value of both T2-weighted spin-echo (SE) and contrast-enhanced dynamic gradient-echo (GRE) sequences using MR imaging in differentiating the deep myometrial invasion from lower stages produced by endometrial carcinoma. For the correlation of MR findings with the histopathologic findings, patients who had no myometrial invasion (stage 1 a) and patients in whom tumors were confined to the superficial myometrium (stage 1 b) at pathologic examination were combined as lower stages. Twenty patients with endometrial carcinoma were studied using both techniques. The absence of any detectable tumor (stage 1 a) or the presence of a tumor confined to inner half of myometrium (stage 1 b) and extention of tumor to the outer half of myometrium (stage 1 c) were used as the diagnostic criteria. In pathologic examination of excised specimens, deep myometrial invasion was detected in 9 of 20 patients. The sensitivity, specificity, accuracy, positive predictive values (PPV) and negative predictive values (NPV) of T2-weighted SE in differentiating deep myometrial invasion from combined lower stages were 88, 91, 90, 88, and 91 %, respectively, whereas corresponding values for contrast-enhanced dynamic GRE sequences were 78, 100, 90, 100, and 85 %. Statistical difference between two sequences did not reach a significant level. We conclude that in cases of absence of visible junctional zone with SE sequence, contrast-enhanced dynamic GRE MR imaging may be helpful.

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Nowadays, environmental impact, safety and fuel efficiency are fundamental issues for the automotive industry. These objectives are met by using a combination of different types of steels in the auto bodies. Therefore, it is important to have an understanding of how dissimilar materials behave when they are welded. This paper presents the process parameters' optimization procedure of fiber laser welded dissimilar high strength low alloy (HSLA) and martensitic steel (MART) steel using a Taguchi approach. The influence of laser power, welding speed and focal position on the mechanical and microstructural properties of the joints was determined. The optimum parameters for the maximum tensile load-minimum heat input were predicted, and the individual significance of parameters on the response was evaluated by ANOVA results. The optimum levels of the process parameters were defined. Furthermore, microstructural examination and microhardness measurements of the selected welds were conducted. The samples of the dissimilar joints showed a remarkable microstructural change from nearly fully martensitic in the weld bead to the unchanged microstructure in the base metals. The heat affected zone (HAZ) region of joints was divided into five subzones. The fusion zone resulted in an important hardness increase, but the formation of a soft zone in the HAZ region.

AA6082-T6 alloy was joined by friction stir spot welding using five different pin profiles, such as a cylindrical, conical, triangular, hexagonal and cylindrical with two grooves, at different dwell time. The joints welded by cylindrical pins had larger effective weld width. But, grooves on the cylindrical pin decreased the effective weld width. The hook was bent downward from the interface of the sheets in the weld made with hexagonal pin, which had the smallest effective weld width. When conical pin was used, effective weld width increased with increasing the dwell time. In the case of using tools with cylindrical and conical pins, HAZ hardness was relatively lower. With increasing dwell time, HAZ hardness of the joints made with conical pin decreased. Effective weld width determined the weld strength under the tensile shear loading condition: Larger effective weld width resulted in higher weld strength. Weld strength of the joints made with cylindrical pin was higher. The joints fabricated with hexagonal pin had the lowest weld strength. In general, higher dwell time led to higher weld strength. The welds with the higher strength experienced both brittle and ductile fractures, while the joints with the lower strength exhibited completely brittle fracture.