Influenza virus infection in pigs is both an animal health problem and a public health concern. As such, surveillance and characterization of influenza viruses in swine is important to the veterinary community and should be a part of human pandemic preparedness planning. Studies in 1976/1977 and 1988/1989 demonstrated that pigs in the U.S. were commonly infected with classical swine H1N1 viruses, whereas human H3 and avian influenza virus infections were very rare. In contrast, human H3 and avian H1 viruses have been isolated frequently from pigs in Europe and Asia over the last two decades. From September 1997 through August 1998, we isolated 26 influenza viruses from pigs in the north central United States at the point of slaughter. All 26 isolates were H1N1 viruses, and phylogenetic analyses of the hemagglutinin and nucleoprotein genes from 11 representative viruses demonstrated that these were classical swine H1 viruses. However, monoclonal antibody analyses revealed antigenic heterogeneity among the HA proteins of the 26 viruses. Serologically, 27.7% of 2,375 pigs tested had hemagglutination-inhibiting antibodies against classical swine H1 influenza virus. Of particular significance, however, the rates of seropositivity to avian H1 (7.6%) and human H3 (8.0%) viruses were substantially higher than in previous studies.

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Human head and neck cancers that develop from the squamous cells of the oropharynx (Oropharyngeal Squamous Cell Carcinomas or OPSCC) are commonly associated with the papillomavirus infection. A papillomavirus infection-based mouse model of oropharyngeal tumorigenesis would be valuable for studying the development and treatment of these tumors. We have developed an efficient system using the mouse papillomavirus (MmuPV1) to generate dysplastic oropharyngeal lesions, including tumors, in the soft palate and the base of the tongue of two immune-deficient strains of mice. To maximize efficiency and safety during infection and endoscopy, we have designed a nose cone for isoflurane-induced anesthesia that takes advantage of a mouse’s need to breathe nasally and has a large window for oral manipulations. To reach and infect the oropharynx efficiently, we have repurposed the Greer Pick allergy testing device as a virus delivery tool. We show that the Pick can be used to infect the epithelium of the soft palate and the base of the tongue of mice directly, without prior scarification. The ability to induce and track oropharyngeal papillomavirus-induced tumors in the mouse, easily and robustly, will facilitate the study of oropharyngeal tumorigenesis and potential treatments.

Purpose: The purpose of this work is to characterize the magnitude and variability of B 0 and B 1 inhomogeneities in the liver in large cohorts of patients at both 1.5 T and 3.0 T. Methods: Volumetric B 0 and B 1 maps were acquired over the liver of patients presenting for routine abdominal MRI. Regions of interest were drawn in the nine Couinaud segments of the liver, and the average value was recorded. Magnitude and variation of measured averages in each segment were reported across all patients. Results: A total of 316 B 0 maps and 314 B 1 maps, acquired at 1.5 T and 3.0 T on a variety of GE Healthcare MRI systems in 630 unique exams, were identified, analyzed, and, in the interest of reproducible research, de-identified and made public. Measured B 0 inhomogeneities ranged (5th-95th percentiles) from −31.7 Hz to 164.0 Hz for 3.0 T (−14.5 Hz to 81.3 Hz at 1.5 T), while measured B 1 inhomogeneities (ratio of actual over prescribed flip angle) ranged from 0.59 to 1.13 for 3.0 T (0.83 to 1.11 at 1.5 T). Conclusion: This study provides robust characterization of B 0 and B 1 inhomogeneities in the liver to guide the development of imaging applications and protocols. Field strength, bore diameter, and sex were determined to be statistically significant effects for both B 0 and B 1 uniformity. Typical clinical liver imaging at 3.

Purpose To develop and validate a T1‐corrected chemical‐shift encoded MRI (CSE‐MRI) method to improve noise performance and reduce bias for quantification of tissue proton density fat‐fraction (PDFF). Methods A variable flip angle (VFA)‐CSE‐MRI method using joint‐fit reconstruction was developed and implemented. In computer simulations and phantom experiments, sources of bias measured using VFA‐CSE‐MRI were investigated. The effect of tissue T1 on bias using low flip angle (LFA)‐CSE‐MRI was also evaluated. The noise performance of VFA‐CSE‐MRI was compared to LFA‐CSE‐MRI for liver fat quantification. Finally, a prospective pilot study in patients undergoing gadoxetic acid‐enhanced MRI of the liver to evaluate the ability of the proposed method to quantify liver PDFF before and after contrast. Results VFA‐CSE‐MRI was accurate and insensitive to transmit B1 inhomogeneities in phantom experiments and computer simulations. With high flip angles, phase errors because of RF spoiling required modification of the CSE signal model. For relaxation parameters commonly observed in liver, the joint‐fit reconstruction improved the noise performance marginally, compared to LFA‐CSE‐MRI, but eliminated T1‐related bias. A total of 25 patients were successfully recruited and analyzed for the pilot study. Strong correlation and good agreement between PDFF measured with VFA‐CSE‐MRI and LFA‐CSE‐MRI (pre‐contrast) was observed before (R2 = 0.97; slope = 0.88, 0.81–0.94 95% confidence interval [CI]; intercept = 1.34, −0.77–1.92 95% CI) and after (R2 = 0.93; slope = 0.88, 0.78–0.98 95% CI; intercept = 1.90, 1.01–2.79 95% CI) contrast. Conclusion Joint‐fit VFA‐CSE‐MRI is feasible for T1‐corrected PDFF quantification in liver, is insensitive to B1 inhomogeneities, and can eliminate T1 bias, but with only marginal SNR advantage for T1 values observed in the liver.