Local specific absorption rate (SAR), global SAR, transmitter power, and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design.

PURPOSE: We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global specific absorption rate (SAR), and maximum and average power for small flip-angle pTx (eight channels) spokes pulses in the torso at 3 T and in the head at 7 T. METHODS: We compare the trade-offs between the above-mentioned quantities using the L-curve method. We use a primal-dual algorithm and a compressed set of local SAR matrices to design radio-frequency (RF) pulses satisfying all regulatory (including local SAR) and hardware constraints. RESULTS: Local SAR can be substantially reduced (factor of 2 or more) by explicitly constraining it in the pulse design process compared to constraining global SAR or pulse power alone. This often comes at the price of increased pulse power. CONCLUSION: Simultaneous control of power and SAR is needed for the design of pTx pulses that are safe and can be played on the scanner. Constraining a single quantity can create large increase in the others, which can then rise above safety or hardware limits. Simultaneous constraint of local SAR and power is fast enough to be applicable in a clinical setting.

Innovative Use of Cadavers in Perioperative Nursing Orientation.

The Periop 101 program administrator at a US Navy medical center worked with personnel in the facility's simulation and bioskills laboratories to develop an innovative perioperative nurse orientation curriculum that included the use of human cadavers during simulation activities. Participants were able to practice common perioperative nursing skills (eg, surgical skin antisepsis) on human cadavers rather than simulation manikins. The orientation program comprises two three-month phases. Participants were evaluated twice during phase 1: at the six-week mark and again six weeks later at the end of the phase. Using the Lasater Clinical Judgment Rubric, the administrator scored participants on their clinical judgment skills; results showed that mean scores increased for all learners between the two evaluation sessions. Practicing skills in a safe environment allows new staff members to learn without fear of causing accidental patient harm, and the additional use of cadavers further increased simulation fidelity and learner satisfaction.