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To evaluate the prevalence of incidental findings on preoperative abdominal computed tomography angiography–computed tomography urography in asymptomatic prospective renal donors.

The objective of the study was to determine the short- and long-term effects of irreversible electroporation (IRE) on the hepatic veins and the perivascular tissue through serial computed tomography (CT) with pathological correlation.

Superparamagnetic iron oxide (SPIO) particles are used as a contrast agent in liver magnetic resonance imaging (MRI). SPIO particles exert their greatest influence on T2‐weighted MR signal intensity. The time‐to‐echo (TE) value that provides optimal contrast has not been systematically studied over the range of clinically relevant field strengths. The purpose of this study was to quantitatively evaluate the TE dependence of the post‐SPIO tumor to liver contrast‐to‐noise ratio (CNR). The hypothesis was that there is a TE that provides an optimal CNR. Subjects having probable metastatic hepatic lesions secondary to colorectal carcinoma were studied. Pre‐ and post‐SPIO images were acquired at TE‐effective (TEeff) equal to 46, 76, and 106 msec by using a turbo spin echo pulse sequence at 0.2 T and 1.5 T. The CNR for all lesions greater than 1 cm in diameter was determined in pre‐ and post‐SPIO images. A paired statistical design was used to identify TE‐related CNR dependencies. The primary findings were as follows. (1) CNR differences attributable to TEeffvariation over the range of 46–106 msec were less than 34%. For 0.2 T, TEeff= 46 msec yielded a statistically significantly greater CNR than did TEeff= 76 or 106 msec. The same was true at the higher field strength, but differences were not significant. (2) Signal‐to‐noise measures suggested that SPIO reduced the lesion signal. (3) Post‐SPIO CNR was significantly greater at 1.5 T than at 0.2 T. The observations indicate that over the field strength range of 0.2–1.5 T, CNR differences attributable to the TEeffvariation, while being statistically significant in some cases, are small relative to those resulting from the SPIO administration. J. Magn. Reason. Imaging 2001;14:586–594, 2001. © 2001 Wiley‐Liss, Inc.

Superparamagnetic iron oxide (SPIO) particles are used as a contrast agent in liver magnetic resonance imaging (MRI). SPIO particles exert their greatest influence on T2-weighted MR signal intensity. The time-to-echo (TE) value that provides optimal contrast has not been systematically studied over the range of clinically relevant field strengths. The purpose of this study was to quantitatively evaluate the TE dependence of the post-SPIO tumor to liver contrast-to-noise ratio (CNR). The hypothesis was that there is a TE that provides an optimal CNR. Subjects having probable metastatic hepatic lesions secondary to colorectal carcinoma were studied. Pre- and post-SPIO images were acquired at TE-effective (TE^eff) equal to 46, 76, and 106 msec by using a turbo spin echo pulse sequence at 0.2 T and 1.5 T. The CNR for all lesions greater than 1 cm in diameter was determined in pre- and post-SPIO images. A paired statistical design was used to identify TE-related CNR dependencies. The primary findings were as follows. (1) CNR differences attributable to TE^eff variation over the range of 46–106 msec were less than 34%. For 0.2 T, TE^eff = 46 msec yielded a statistically significantly greater CNR than did TE^eff = 76 or 106 msec. The same was true at the higher field strength, but differences were not significant. (2) Signal-to-noise measures suggested that SPIO reduced the lesion signal. (3) Post-SPIO CNR was significantly greater at 1.5 T than at 0.2 T. The observations indicate that over the field strength range of 0.2–1.5 T, CNR differences attributable to the TE^eff variation, while being statistically significant in some cases, are small relative to those resulting from the SPIO administration. J. Magn. Reason. Imaging 2001;14:586–594, 2001. © 2001 Wiley-Liss, Inc.

Magnetic radiofrequency (RF) fields applied during magnetic resonance imaging (MRI) may induce heating in devices made from conductive materials. The present paper reports on theoretical and experimental studies on the RF heating resonance phenomenon of an endovascular guidewire. A nitinol‐based guidewire was inserted into a vessel phantom and imaged at 1.5 and 0.2 T with continuous temperature monitoring at the guidewire tip. The heating effects due to different experimental settings were examined. A model is developed for the resonant current and the associated electric field produced by the guidewire acting as an antenna. Temperature increases of up to 17° C were measured while imaging the guidewire at an off‐center position in the 1.5 T MR system. Power absorption produced by the resonating wire decreased as the repetition time was increased. No temperature rise was measured at 0.2 T. Considering the potential utility of low‐field, open MR systems for MRI‐guided endovascular interventions, it is important to be aware of the safety of such applications. J. Magn. Reson. Imaging 2000;12:75–78. © 2000 Wiley‐Liss, Inc.

Magnetic radiofrequency (RF) fields applied during magnetic resonance imaging (MRI) may induce heating in devices made from conductive materials. The present paper reports on theoretical and experimental studies on the RF heating resonance phenomenon of an endovascular guidewire. A nitinol-based guidewire was inserted into a vessel phantom and imaged at 1.5 and 0.2 T with continuous temperature monitoring at the guidewire tip. The heating effects due to different experimental settings were examined. A model is developed for the resonant current and the associated electric field produced by the guidewire acting as an antenna. Temperature increases of up to 17° C were measured while imaging the guidewire at an off-center position in the 1.5 T MR system. Power absorption produced by the resonating wire decreased as the repetition time was increased. No temperature rise was measured at 0.2 T. Considering the potential utility of low-field, open MR systems for MRI-guided endovascular interventions, it is important to be aware of the safety of such applications. J. Magn. Reson. Imaging 2000;12:75–78. © 2000 Wiley-Liss, Inc.

The authors tested the effect of 195 KHz therapeutic ultrasound energy on gallstone dissolution in concert with methyl tert-butyl ether (MTBE) in vitro.

Significant technologic advances have taken place in computed tomography (CT). Current-generation conventional CT scanners are able to image a slice of tissue in as little as 2 to 3 seconds and can acquire several consecutive images. Although it is a substantial improvement from the CT of 5 years ago, there remain practical limits to the utility of conventional CT imaging within the abdomen. Recently, a new type of CT gantry design (“slip-ring”) and faster computers have contributed to the development of a new generation of CT scanners, the “helical” or “spiral” CT scanners.

Abstract. Significant technologic advances have taken place in computed tomography (CT). Current-generation conventional CT scanners are able to image a slice of tissue in as little as 2 to 3 seconds and can acquire several consecutive images. Although it is a substantial improvement from the CT of 5 years ago, there remain practical limits to the utility of conventional CT imaging within the abdomen. Recently, a new type of CT gantry design (“slip-ring”) and faster computers have contributed to the development of a new generation of CT scanners, the “helical” or “spiral” CT scanners.: