Electromagnetic analysis of the slotted-tube resonator with a circular cross section for MRI applications.

In this paper we present electromagnetic (EM) analysis of the unloaded slotted-tube resonator (STR) with a circular cross section, using the finite element method (FEM) and method of moments (MoM) in two dimensions. This analysis allows the determination of the primary parameters: [L] and [C] matrices, optimization of the field homogeneity, and simulates the frequency response of S(11) at the RF port of the designed STR. The optimum configuration is presented, taking into account the effect of the thickness of the STR and the effect of the RF shield. As an application, we present the design results of a MRI probe using the STR and operating at 500 MHz (proton imaging at 11.74 T). The resonator has -69.37 dB minimum reflection and an unloaded quality factor (Q(o)) > 500 at 500 MHz.

Analysis and design of a coupled coaxial line TEM resonator for magnetic resonance imaging.

In this paper, we have successfully realized a numerical tool to analyse and to design an n-element unloaded coaxial line transverse electromagnetic (TEM) resonator. This numerical tool allows the determination of the primary parameters, matrices [L], [C] and [R], and simulates the frequency response of S11 at the RF port of the designed TEM resonator. The frequency response permits evaluation of the unloaded quality factor Q0. As an application, we present the analysis and the design of an eight-element unloaded TEM resonator for animal studies at 4.7 T. The simulated performance has a -62.81 dB minimum reflection and a quality factor of 260 around 200 MHz.

[4p trisomy secondary to paternal translocation t(4p-;15q+)]. / Trisomie 4p secondaire à une translocation paternelle t(4p-;15q+).

A new case of trisomy 4p is reported. The patient was a boy with dysmorphism, growth failure and developmental retardation. Craniofacial features included microcephaly with a flat forehead, a prominent glabella, hyperteleorism, a broad, concave nasal bridge, a bulb-shaped nose, a wide mouth with a prominent upper lip and a short philtrum, low-set ears, a low hairline, micrognathia, and a short neck. Abdominal muscles were normal. Cryptorchidism with a hypoplastic scrotum and a micropenis were found, as well as forced flexion of the fingers and talipes equinus. The intravenous urogram disclosed ptosis of the right kidney. Developmental retardation was severe with an IQ under 50. RHG banding techniques on peripheral lymphocytes disclosed 4p14 pter duplication. The karyotype was 46,XY inv dup(4-p) (p14----pter). The mother's karyotype was normal. The father had a translocation between the short arm of chromosome 4 and the long arm of chromosome 15; his karyotype was 46,XY, t(4;15) (p14;q26). Thus, the child had trisomy for a segment of the short arm of chromosome 4 (p14----pter) and monosomy for the terminal band of the long arm of chromosome 15 (15q26). The first case of trisomy 4p was reported in 1970 by Wilson et al. Since then, there have been 46 additional reports in the medical literature. Although children with trisomy 4p share a number of features, the phenotypic manifestations of this chromosomal abnormality are variable and nonspecific, making clinical diagnosis difficult.