Abstract The approach, design, and implementations for CONTRAST, a user interface that visualizes... more Abstract The approach, design, and implementations for CONTRAST, a user interface that visualizes concepts in magnetic resonance imaging (MRI), are described. An introduction to medical MRI is given, along with the approach to building the CONTRAST expert system. The domain-specific visual representations used in the CONTRAST user interface are discussed, as are overall interface architecture, the use of the interface for explanation, and an associated tutorial program. Some comments on building high-bandwidth user ...
Objective: To evaluate the impact of MRI on ICD sensing of ventricular tachyarrhythmias. Methods:... more Objective: To evaluate the impact of MRI on ICD sensing of ventricular tachyarrhythmias. Methods: The Evera MRI study is the first randomized trial of an ICD designed specifically to be MRI safe. This was a world-wide trial of 263 pts implanted with an Evera MRI single or dual chamber ICD in 42 centers. Patients were randomized to either undergo an MRI scan (MRI group) or to not receive a study MRI scan. Per protocol, 156 MRI group pts underwent an MRI procedure at 9-12 weeks post-implant. Device detected spontaneous and induced VT/VF episodes in the MRI group occurring prior to and following MRI were evaluated by an independent Episode Review Committee blinded to the timing of events. Detection delay was computed as the sum of RR intervals of under sensed beats. A ≥5 second delay in detection due to under sensing was prospectively defined as clinically significant. P-values are adjusted for multiple episodes within a patient. Results: There were a total of 34 post-MRI VT/VF episodes in 24 pts, with 16 of those pts having 27 VT/VF episodes prior to MRI. The mean detection delay due to under sensing in the 23 pre-MRI treated episodes was 0.37 ± 0.57 seconds, compared to 0.25 ± 0.57 in 27 treated post-MRI episodes (p=0.29). The maximum detection delay was 2.19 seconds pre-MRI and 2.87 seconds post-MRI. Monomorphic VT and non-sustained VT/VF rarely had any under sensing with 1/11 (9%) pre-MRI episodes and 1/14 (7%) post-MRI episodes (p=0.81) having 2 and 1 under sensed beats, respectively. For polymorphic VT/VF episodes, 13/16 (81%) pre-MRI episodes had some detection delay vs. 10/20 (50%) in post-MRI episodes (p=0.052), but no detection delay was clinically significant. The duration of delay was 0.54 ± 0.61 vs 0.32 ± 0.64, respectively, p=0.28). Conclusion: Detection of VT/VF was excellent with no significant impact of MRI with this system.
Pacing and Clinical Electrophysiology, Oct 30, 2015
Device implanters regularly face a fork in the road. They have to choose which device to place in... more Device implanters regularly face a fork in the road. They have to choose which device to place in each patient. As noted by Ferreira, et al. "There is currently no consensus regarding who should receive an MRI-conditional pacemaker. Opinions range from universal adoption to almost complete dismissal, as some critics consider that the increased cost is unjustified and that conventional pacemakers can be safely scanned with appropriate precautions." (1) And while 50-75 percent of patients with devices will need a magnetic resonance imaging (MRI) scan during their lifetime, physician surveys suggest MRI labeling is of only modest importance to them. (2) This article is protected by copyright. All rights reserved.
... of Pittsburgh School of Medicine (Dr Kanal, Mr Gillen); and the Safety Committee of the Socie... more ... of Pittsburgh School of Medicine (Dr Kanal, Mr Gillen); and the Safety Committee of the Society of Magnetic Resonance Imaging (Dr Kanal). ... including video display ter-minals, electric power lines, and elec-tric blankets, have recently been tar-geted as possible contributors to ...
Journal of Magnetic Resonance Imaging, May 1, 1995
Magnetic resonance angiography is most commonly performed with the three‐dimensional (3D) time‐of... more Magnetic resonance angiography is most commonly performed with the three‐dimensional (3D) time‐of‐flight (TOP) technique. As currently practiced, this requires long image acquisition times (5–10 minutes). The authors show that the acquisition time of 3D TOP images can be reduced to less than 1 minute by using a very short TR (<10msec). Under normal flow conditions, the major vessels of the circle of Willis were consistently well demonstrated on these fast 3D TOP images. Signal saturation was observed in studies of patients with abnormal blood flow. In those cases, it was demonstrated that serial acquisition of fast 3D TOP data during and after contrast agent administration could be used to overcome the saturation effects. Time‐resolved fast 3D TOP imaging during and after contrast agent administration can also provide qualitative assessment of flow and may depict other features that cannot be observed in TOP studies with long imaging times.
Abstract The approach, design, and implementations for CONTRAST, a user interface that visualizes... more Abstract The approach, design, and implementations for CONTRAST, a user interface that visualizes concepts in magnetic resonance imaging (MRI), are described. An introduction to medical MRI is given, along with the approach to building the CONTRAST expert system. The domain-specific visual representations used in the CONTRAST user interface are discussed, as are overall interface architecture, the use of the interface for explanation, and an associated tutorial program. Some comments on building high-bandwidth user ...
Objective: To evaluate the impact of MRI on ICD sensing of ventricular tachyarrhythmias. Methods:... more Objective: To evaluate the impact of MRI on ICD sensing of ventricular tachyarrhythmias. Methods: The Evera MRI study is the first randomized trial of an ICD designed specifically to be MRI safe. This was a world-wide trial of 263 pts implanted with an Evera MRI single or dual chamber ICD in 42 centers. Patients were randomized to either undergo an MRI scan (MRI group) or to not receive a study MRI scan. Per protocol, 156 MRI group pts underwent an MRI procedure at 9-12 weeks post-implant. Device detected spontaneous and induced VT/VF episodes in the MRI group occurring prior to and following MRI were evaluated by an independent Episode Review Committee blinded to the timing of events. Detection delay was computed as the sum of RR intervals of under sensed beats. A ≥5 second delay in detection due to under sensing was prospectively defined as clinically significant. P-values are adjusted for multiple episodes within a patient. Results: There were a total of 34 post-MRI VT/VF episodes in 24 pts, with 16 of those pts having 27 VT/VF episodes prior to MRI. The mean detection delay due to under sensing in the 23 pre-MRI treated episodes was 0.37 ± 0.57 seconds, compared to 0.25 ± 0.57 in 27 treated post-MRI episodes (p=0.29). The maximum detection delay was 2.19 seconds pre-MRI and 2.87 seconds post-MRI. Monomorphic VT and non-sustained VT/VF rarely had any under sensing with 1/11 (9%) pre-MRI episodes and 1/14 (7%) post-MRI episodes (p=0.81) having 2 and 1 under sensed beats, respectively. For polymorphic VT/VF episodes, 13/16 (81%) pre-MRI episodes had some detection delay vs. 10/20 (50%) in post-MRI episodes (p=0.052), but no detection delay was clinically significant. The duration of delay was 0.54 ± 0.61 vs 0.32 ± 0.64, respectively, p=0.28). Conclusion: Detection of VT/VF was excellent with no significant impact of MRI with this system.
Pacing and Clinical Electrophysiology, Oct 30, 2015
Device implanters regularly face a fork in the road. They have to choose which device to place in... more Device implanters regularly face a fork in the road. They have to choose which device to place in each patient. As noted by Ferreira, et al. "There is currently no consensus regarding who should receive an MRI-conditional pacemaker. Opinions range from universal adoption to almost complete dismissal, as some critics consider that the increased cost is unjustified and that conventional pacemakers can be safely scanned with appropriate precautions." (1) And while 50-75 percent of patients with devices will need a magnetic resonance imaging (MRI) scan during their lifetime, physician surveys suggest MRI labeling is of only modest importance to them. (2) This article is protected by copyright. All rights reserved.
... of Pittsburgh School of Medicine (Dr Kanal, Mr Gillen); and the Safety Committee of the Socie... more ... of Pittsburgh School of Medicine (Dr Kanal, Mr Gillen); and the Safety Committee of the Society of Magnetic Resonance Imaging (Dr Kanal). ... including video display ter-minals, electric power lines, and elec-tric blankets, have recently been tar-geted as possible contributors to ...
Journal of Magnetic Resonance Imaging, May 1, 1995
Magnetic resonance angiography is most commonly performed with the three‐dimensional (3D) time‐of... more Magnetic resonance angiography is most commonly performed with the three‐dimensional (3D) time‐of‐flight (TOP) technique. As currently practiced, this requires long image acquisition times (5–10 minutes). The authors show that the acquisition time of 3D TOP images can be reduced to less than 1 minute by using a very short TR (<10msec). Under normal flow conditions, the major vessels of the circle of Willis were consistently well demonstrated on these fast 3D TOP images. Signal saturation was observed in studies of patients with abnormal blood flow. In those cases, it was demonstrated that serial acquisition of fast 3D TOP data during and after contrast agent administration could be used to overcome the saturation effects. Time‐resolved fast 3D TOP imaging during and after contrast agent administration can also provide qualitative assessment of flow and may depict other features that cannot be observed in TOP studies with long imaging times.
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Papers by Emanuel Kanal