MRSO Exam 4 with Complete Solutions 2024.

MRSO Exam 4 with Complete Solutions 2024. Peripheral nerve stimulation can be described by which of the following? a. Faraday's law of induction b. Ohm's law c. Lenz's law d. Planks Law - ANSWER-b. Faraday's law of induction (describes the induction of electrical current in the presence of a changing magnetic field). Lenz's force describes the opposing forces created. Ohm's law deals with the resistance of current along a wire. Gad contrast has been found in the body in what form? Select all that apply. a. Water-soluble b. Non-water soluble - ANSWER-a, b Which of the following would we expect to be the loudest sequence? a. GRASS b. Fast spin echo c. Conventional gradient sequence d. FLAIR - ANSWER-a. GRASS The FLAIR and fast spin echo are considered spin echo sequences; they do not have extremely fast changing gradient, so will not produce as much noise. Which of the following has a steeper spatial magnetic gradient? a. Vertical B0 b. Horizontal B0 - ANSWER-a. Vertical B0 The strongest gradient strength will reach maximum strength how far from isocenter? a. 5-20 cm b. 20-40 cm c. 30-60 cm d. 5-15 cm - ANSWER-c. 30-60 cm Which of the following is true of gad and breastfeeding mothers? Select all that apply. a. Gad is found in breast milk in a stable and chelated form b. It is thought that gad contrast may alter the taste of breastmilk. c. Available data suggests that breastmilk should be pumped and discarded for 24 hours after the IV dose d. 20% of the intravascular dose would be excreted into the breastmilk within the first 24 hours. - ANSWER-a, b Which of the following will influence peripheral nerve stimulation? a. Static magnetic field b. Magnetic field at isocenter c. Patient weight d. Slew rate - ANSWER-d. Slew rate Which of the following pulse sequences would we expect to see the least patient heating? a. Incoherent gradient b. STIR c. Fast spin echo d. EPI - ANSWER-d. EPI A patient comes in with a 1 cm brain aneurysm clip and you find the package which lists what metal it is made from. Which of the following metals would make it unsafe to scan this patient? a. Elgiloy b. Phynox c. MP35N d. 405 Stainless steel - ANSWER-d. 405 Stainless steel Phynox, elgiloy, titanium, and 316 stainless steel are non-ferrous. 17-7PH and 405 stainless steel are ferrous Which of the following are true of Lenz's force? a. Occurs because of the interaction between a ferrous object and the static magnetic field b. Influences objects that are electrically conductive c. Influence on an object depends on the field strength d. Increases with the rate of motion through the static magnetic field. - ANSWER-b, c, d Lenz's law is caused when an electrically conductive object (not ferrous) interacts with a strong magnetic field. The speed that the object translates through the magnetic field as well as its dimensions, orientation, and the overall magnetic field will influence the amount of Lenz's force on an object. This force acts as a repulsive force when translating through the static magnetic field. A patient is having an MR lumbar spine in normal mode. We know that the SAR will not exceed which of the following? a. 4 W/kg b. 3 W/kg c. 2 W/kg d. 1 W/kg - ANSWER-c. 2 W/kg .