Analysis of signal-to-noise behavior in Cartesian continuous sampling sequences: predictions and experimental validation of opportunities for improved image SNR.

Image signal-to-noise ratio (SNR) limits many MRI applications. Here we propose a method to improve SNR based on continuous sampling (CS) during each TR without significant increases in acquisition time. The general concept of CS is defined here as sampling the NMR signal immediately after slice excitation including ramp times, both the dephase and rephase lobes, the phase-encoding (PE) gradient application, and the slice refocusing gradient. This study analyzes several cases of CS and demonstrates a specific case where sampling occurs during an isolated and balanced readout gradient in order to increase SNR in a rectilinear Cartesian sequence without significantly increasing overall acquisition time. The noise correlation consequences of rectilinear CS are mathematically derived and proven through simulation. The SNR improvement of up to approximately 40% measured in both phantom and asymptomatic human volunteer images is comparable to theoretical prediction of increased SNR proportional to the increase in the square root of the sampling time.     

Global molecular epidemiology of the O15:K52:H1 extraintestinal pathogenic Escherichia coli clonal group: evidence of distribution beyond Europe

Escherichia coli O15:K52:H1 is a significant extraintestinal pathogen in Europe (G. Prats et al., J. Clin. Microbiol. 38:201-209, 2000). To search for evidence of this clonal group outside of Europe, 75 non-European E. coli isolates of serogroup O15 were compared with five members of the O15:K52:H1 clonal group from Barcelona, Spain, according to genomic background, virulence genotypes, and antimicrobial resistance profiles. Amplification phylotyping showed that 16 (21%) of the 75 non-European O15 isolates corresponded with the O15:K52:H1 clonal group. The 16 non-European O15:K52:H1 clonal group members represented diverse geographic locales. They were isolated almost exclusively from humans with extraintestinal infections and accounted for 50% of all O15 isolates from five human clinical collections studied. Most non-European clonal group members exhibited a consensus virulence factor profile that included the F16 or F7-2 papA alleles (P fimbrial structural subunit), papG allele II (P fimbrial adhesin), iha (putative adhesin siderophore), and iutA (aerobactin receptor). This resembles the virulence profiles of (i) European representatives of the O15:K52:H1 clonal group and (ii) phylogenetically related "clonal group A," a recently recognized significant contributor to trimethoprim-sulfamethoxazole resistance in the United States (A. R. Manges et al., N. Engl. J. Med. 345:1007-1013, 2001). Antimicrobial resistance profiles were variable, and resistance was inconsistently transferred by conjugation. These findings indicate that the O15:K52:H1 clonal group is broadly distributed beyond Europe, exhibits previously unrecognized phenotypic and genotypic diversity, and contributes significantly to extraintestinal infections in humans.     

Ameloblastic fibrosarcoma of the jaws--report of three cases. Clinico-pathologic, histoenzymological and ultrastructural study

The ameloblastic fibrosarcoma is a rare variety of neoplasm. Three new cases reported here occurred within preexistent benign odontogenic tumors (ameloblastic fibroma or fibro-odontoma). These large, osteolytic tumors, spreading to adjacent soft parts, recurred after surgical treatment in two cases. One of them had a lethal course, with pleuro-pulmonary, mediastinal lymph node and hepatic metastases. Histologically, these sarcomas show a malignant mesenchymal component and few benign ameloblastic islands, which often disappear after one or several recurrences. Histoenzymologically, a high level of alkaline phosphatase and ATPase activities is always present, a feature not present in common fibrosarcomas. The ultrastructural study demonstrates, in analogy with odontogenic myxomas, clear cells provided with numerous microfilaments, secretory cells and also some fibroblasts and myofibroblast-like cells. In addition to these pleomorphic cells, a great number of peculiar granular cells with numerous lysosomal bodies were also found. The histogenesis of these tumors in unknown. Perhaps the epithelial component, being unable to assume its functions of organization, may initiate the malignant transformation of its odontogenic mesenchyme.     

Measurement of left-ventricular volumes using an internal standard

When performing equilibrium radionuclide angiocardiography with two successive acquisition views, absolute left-ventricular volumes can be calculated using an internal standard generated by a computer in the left-ventricular cavity. The method is based on the computed ratio of maximum to global activity in the 40°-left-anterior-oblique view after background correction and on the measured depth of the left ventricle in almost-orthogonal, 30°-left-posterior-oblique Fourier first-harmonic images. The method does not require blood sampling or correction for self attenuation. The intra- and interobserver reproducibility is excellent, even in patients with severe impairment of the ventricular-contractility pattern. When compared with a classical method requiring venous-blood counting and an attenuation correction factor, the accuracy of the internalstandard method was fairly good, with a regression coefficient of 0.90.     

Preterm Birth Among US and Foreign-Born Non-Hispanic Black Birthing Parents in Massachusetts: Variation by Nativity,Region, and Country of Origin

Maternal and Child Health Journal - Foreign-born non-Hispanic Black (NHB) birthing parents are less likely to have a preterm birth (PTB) than US-born NHBs. There is further variation by region and...     

ASO Visual Abstract: Chemotherapy After Diagnosis of Malignant Bowel Obstruction is Associated with Greater Survival for Medicare Patients with Advanced Malignancy

Annals of Surgical Oncology -