Case 16.18

64-year-old woman with a history of fevers and anemia Coronal SSFSE (Figure 16.18.1) and fat-suppressed SSFP (Figure 16.18.2) images demonstrate a heterogeneous mass expanding the intrahepatic IVC. Coronal source image from venous phase acquisition of a 3D CE MRA (...

Case 7.32

62-year-old woman with chest discomfort and right upper quadrant pain Coronal source image from 3D contrast-enhanced MRA (Figure 7.32.1) shows a prominent eccentric thrombus in the lumen of the posterior aortic arch. Post-MRA, 2D SPGR axial images (Figure 7.32.2) through the upper abdomen demonstrate a large region of absent perfusion in the right kidney, with preserved capsular enhancement....

Helicity transport in a simulated coronal mass ejection

It has been suggested that coronal mass ejections (CMEs) remove the magnetic helicity of their coronal source region from the Sun. Such removal is often regarded to be necessary due to the hemispheric sign preference of the helicity, which inhibits a simple annihilation by reconnection between volumes of opposite chirality. Here we monitor the relative magnetic helicity contained in the coronal volume of a simulated flux rope CME, as well as the upward flux of relative helicity through horizontal planes in the simulation box. The unstable and erupting flux rope carries away only a minor part of the initial relative helicity; the major part remains in the volume. This is a consequence of the requirement that the current through an expanding loop must decrease if the magnetic energy of the configuration is to decrease as the loop rises, to provide the kinetic energy of the CME.