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183 results on '"Hangiandreou, Nicholas J."'

1. Prospective Study Assessing Impact of Ethylene Oxide Sterilization on Endoscopic Ultrasound Image Quality

Author

Majumder, Shounak, Long, Zaiyang, Hooke, Alexander W., Petersen, Bret T., Gleeson, Ferga C., Bruno, Marco, DeWitt, John, Elta, Grace, Fuji, Larissa, Gomez, Victoria, Palazzo, Laurent, Shami, Vanessa M., Stevens, Tyler, Topazian, Mark D., Wiersema, Maurits J., Berglund, Lawrence J., Abu Dayyeh, Barham K., Chandrasekhara, Vinay, Iyer, Prasad G., Rajan, Elizabeth, Storm, Andrew C., Wang, Kenneth K., Lennon, Ryan, Larson, Joseph J., Enders, Felicity T., Frein, Jed R., Yates, Raymond A., Hangiandreou, Nicholas J., and Levy, Michael J.

Published
2022
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2. Technical Note: Impact of Linear Array Transducer Doppler Aperture Location on Spectral Peak Velocity Measurements - A Phantom Study.

Author

Long, Zaiyang, Hangiandreou, Nicholas J., Macedo, Thanila A., Tradup, Donald J., and Hesley, Gina K.

Subjects
*TRANSDUCERS, *VELOCITY measurements, *ADVECTION, *SCANNING systems, *ULTRASONIC imaging
Abstract

Ultrasound beams sometimes need to be steered from the edge of linear array transducers to reach the sample volume with a desired Doppler angle in vascular exams. This phantom study aims to evaluate the impact of apertures located at the array edge on peak velocity (PV) measurements. Three ultrasound scanner systems equipped with eight transducers from 3 major ultrasound vendors were tested using a flow phantom with a horizontal tube. Five spectral Doppler measurements with the aperture positioned at one edge of the array and 5 with the aperture at the center of the array were obtained using all available scanner-transducer combinations while maintaining all scan parameters and the sample volume in the same tube location. Differences in PVs between center and edge apertures were compared across 4 constant flow rates. The averaged PVs for all phantom flow rates ranged from 24.4 cm/s to 138.2 cm/s from the array center. The averaged PVs from the center aperture were significantly greater than the corresponding measurements from the edge aperture for each flow rate (all p < 0.001). The relative PV differences ranged from 6.7% to 19.4% across all transducers and flow rates. Significantly lower PVs were consistently shown with the Doppler beam aperture at the array edge compared to center among all tested systems. This may be due to a narrower aperture width, shifted central axis, and less intrinsic spectral broadening error at the array edge. Controlling variations in Doppler aperture location is important in clinical applications which depend on consistent velocity measurements. [ABSTRACT FROM AUTHOR]

Published
2024
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29. 1121 PROSPECTIVE, MULTI-CENTER 2 YEAR STUDY TO DETERMINE THE INFLUENCE OF HIGH-LEVEL DISINFECTION ALONE VERSUS ETHYLENE OXIDE STERILIZATION WITH HIGH-LEVEL DISINFECTION ON ENDOSCOPIC ULTRASOUND (EUS) IMAGING

Author

Majumder, Shounak, primary, Long, Zaiyang, additional, Hooke, Alexander W., additional, Petersen, Bret T., additional, Gleeson, Ferga C., additional, Bruno, Marco J., additional, DeWitt, John M., additional, Elta, Grace H., additional, Fujii-Lau, Larissa L., additional, Gomez, Victoria, additional, Palazzo, Laurent, additional, Shami, Vanessa M., additional, Stevens, Tyler, additional, Topazian, Mark, additional, Wiersema, Maurits, additional, Berglund, Lawrence J., additional, Lennon, Ryan J., additional, Larson, Joseph J., additional, Enders, Felicity, additional, Frein, Jed, additional, Yates, Raymond A., additional, Hangiandreou, Nicholas J., additional, and Levy, Michael J., additional

Published
2019
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41. Use of a radio frequency shield during 1.5 and 3.0 Tesla magnetic resonance imaging: experimental evaluation

Author

Favazza,Christopher P, King,Deirdre M, Edmonson,Heidi A, Felmlee,Joel P, Rossman,Phillip J, Hangiandreou,Nicholas J, Watson,Robert E, Gorny,Krzysztof R, Favazza,Christopher P, King,Deirdre M, Edmonson,Heidi A, Felmlee,Joel P, Rossman,Phillip J, Hangiandreou,Nicholas J, Watson,Robert E, and Gorny,Krzysztof R

Abstract

Christopher P Favazza, Deirdre M King, Heidi A Edmonson, Joel P Felmlee, Phillip J Rossman, Nicholas J Hangiandreou, Robert E Watson, Krzysztof R Gorny Department of Radiology, Mayo Clinic, Rochester, MN, USA Abstract: Radiofrequency (RF) shields have been recently developed for the purpose of shielding portions of the patient's body during magnetic resonance imaging (MRI) examinations. We present an experimental evaluation of a commercially available RF shield in the MRI environment. All tests were performed on 1.5 T and 3.0 T clinical MRI scanners. The tests were repeated with and without the RF shield present in the bore, for comparison. Effects of the shield, placed within the scanner bore, on the RF fields generated by the scanner were measured directly using tuned pick-up coils. Attenuation, by as much as 35 dB, of RF field power was found inside the RF shield. These results were supported by temperature measurements of metallic leads placed inside the shield, in which no measurable RF heating was found. In addition, there was a small, simultaneous detectable increase (~1 dB) of RF power just outside the edges of the shield. For these particular scanners, the autocalibrated RF power levels were reduced for scan locations prescribed just outside the edges of the shield, which corresponded with estimations based on the pick-up coil measurements. Additionally, no significant heating during MRI scanning was observed on the shield surface. The impact of the RF shield on the RF fields inside the magnet bore is likely to be dependent on the particular model of the RF shield or the MRI scanner. These results suggest that the RF shield could be a valuable tool for clinical MRI practices. Keywords: radiofrequency shield, magnetic resonance imaging, radiofrequency attenuation

Published
2014

44. Breast Lesions: Evaluation with US Strain Imaging–Clinical Experience of Multiple Observers1

Author

Regner, Dawn M., Hesley, Gina K., Hangiandreou, Nicholas J., Morton, Marilyn J., Nordland, Michelle R., Meixner, Duane D., Hall, Timothy J., Farrell, Michael A., Mandrekar, Jayawant N., Harmsen, W. Scott, and Charboneau, J. William

Subjects
Adult, Aged, 80 and over, Observer Variation, Reproducibility of Results, Breast Neoplasms, Middle Aged, Sensitivity and Specificity, Article, Diagnosis, Differential, Humans, Female, Prospective Studies, Aged, Ultrasonography
Abstract

To prospectively determine the accuracy of using an ultrasonographic (US) strain imaging technique known as lesion size comparison to differentiate benign from malignant breast lesions.Institutional Review Board approval and patient informed consent were obtained for this HIPPA-compliant study. US strain imaging was performed prospectively for 89 breast lesions in 88 patients. Lesions were imaged by using freehand compression and a real-time strain imaging algorithm. Five observers obtained manual measurements of lesion height, width, and area from B-mode and strain images. By using these size measurements, individual observer and group performances were assessed by using the area under the receiver operating characteristic curve (A(z)). The performance of a single size parameter versus that of a combination of size parameters was evaluated by using univariate and multivariate logistic regression.Group A(z) values showed that width ratio and area ratio yielded the best results for differentiating benign and malignant breast lesions, and they were not statistically different from one another (P = .499). For the group, the performance of area and width, which was superior to that of height and aspect ratio, was statistically significant for all cases (P.011) except for those that compared area with aspect ratio (P = .118). By using a group threshold of 1.04 for width ratio and 1.13 for area ratio, the sensitivity and specificity of the technique were 96% and 21%, respectively, for width and 96% and 24%, respectively, for area. The best observer achieved a sensitivity of 96% and a specificity of 61% by using the area ratio. For all but one observer, combined size parameters did not improve observer performance (P.258). Significant interobserver performance variability was observed (P.001).Results suggest that US strain imaging has the potential to aid diagnosis of breast lesions. However, manually tracing lesion boundaries for size ratio differentiation in a busy clinical setting did not match the diagnostic performance levels previously reported. Focusing on measurements of lesion width, along with additional observer training or automated processes, may yield a suitable method for routine clinical application.

Published
2006

47. ACR–AAPM–SIIM Practice Guideline for Digital Radiography

Author

Andriole, Katherine P., primary, Ruckdeschel, Thomas G., additional, Flynn, Michael J., additional, Hangiandreou, Nicholas J., additional, Jones, A. Kyle, additional, Krupinski, Elizabeth, additional, Seibert, J. Anthony, additional, Shepard, S. Jeff, additional, Walz-Flannigan, Alisa, additional, Mian, Tariq A., additional, Pollack, Matthew S., additional, and Wyatt, Margaret, additional

Published
2012
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49. Magnetic Resonance–guided Focused Ultrasound of Uterine Leiomyomas: Review of a 12-month Outcome of 130 Clinical Patients

Author

Gorny, Krzysztof R., primary, Woodrum, David A., additional, Brown, Douglas L., additional, Henrichsen, Tara L., additional, Weaver, Amy L., additional, Amrami, Kimberly K., additional, Hangiandreou, Nicholas J., additional, Edmonson, Heidi A., additional, Bouwsma, Esther V., additional, Stewart, Elizabeth A., additional, Gostout, Bobbie S., additional, Ehman, Dylan A., additional, and Hesley, Gina K., additional

Published
2011
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