and both have metallic implants: LEFT KNEE STD (exclude T2 MAP) Date of Birth, Sex, and Weight are entered appropriately, and Patient Position should be Supine. OAI Right (Left) Knee should be selected from the Study drop-down list. 1.3 Procedure for Repeat Exams Repeat exams should be performed as quickly as possible. Ideally, MRIs of insufficient quality should be identified by the MRI technologist at the time of acquisition and repeated immediately. Repeat exams should be taken within 3 weeks of the original MRI. 2.0 Knee MRI Exam Specifics 2.1 Positioning the Participant for the Knee MRI Proper participant set up should ensure correct positioning of the knee and sufficient participant comfort to limit motion artifacts. 1. The knee coil base should be positioned on the in alignment with the alignment marks on the table. 2. The knee coil should be used in only the L60 or R60 positions. 3. The knee pad should be inserted into the coil; this is the only pad that should be used beneath the knee such that the correct of flexion can be achieved in a consistent manner. The pad should be positioned such that it over hangs the coil edge by -1.5cm. 4. The knee should be positioned in the coil such that the bottom of the patella is aligned with the center mark of the coil. 5. The leg should be in a relaxed, neutral position. 6. The foot should be vertical, with medial foot and the big toe orthogonal to the bed. The foot should be sandbagged to retain this position. 7. The air cushion should be positioned centered on the patella (remove air first, leave valve open) before securing the top and bottom halves of the RF coil. 8. A positioning strap should be used secure both the coil and the contralateral knee. Pads should be used to ensure patient comfort. 9. The landmark position should be the center of the RF coil (align with marks) which should correspond to the bottom of the patella.
If the inside sphere volume measured from the 3D image acquisition differs from the absolute volume by more than 5%, a repeat exam will be requested at the earliest opportunity. If the inside length of the phantom measured from the 3D image acquisition differs from the absolute length by more than 1% (of 125 = 1.25mm), a repeat exam will be requested at the earliest opportunity. The T2 values of the solutions contained within the phantom will be calculated from the images. If the calculated values vary from the known values by more than 5 ms, a repeat exam will be requested at the earliest opportunity. If the system fails a repeat exam, the site will be instructed to call Siemens service. 5.4.2 Body Coil S/N and Calc Artifacts Tests These tests use the Siemens Body Loader and Spherical Phantom (D240). Refer to the instructions in the Siemens Syngo MR Software, Options, Customer QA menu. Position body loader on the patient table. Note: this will likely require the assistance of a second person. Position the spherical phantom in its holder and insert the assembly into the body loader. Ensure that the arrow on the phantom holder is pointing toward the magnet bore. Align loader and phantom with the laser crosshairs. Select Options, Customer QA from the operating menu. Select the coil from the Active Coil selection list. Select the Body S/N DIP checkbox. Select the Calc Artifacts checkbox. Click on the Start button. Decision Tree for Body Coil S/N and Calc Artifacts Tests: If the system fails any one of the tests, check the positions of the phantoms (refer to Customer QA menu instructions) and repeat the exam. If the system fails a second time, reboot the system with the head coil and SNR phantom in position, let the phantom settle for 3-5 minutes, run Head Coil S/N DIP (Customer QA Menu), and record on the SNR log sheet. If the Head S/N passes, then re-run the body coil tests. If the system fails the Head S/N test, try once again. If the Head S/N continues to fail, call Siemens Service. If the system continues to fail Body S/N two attempts and after passing the Head S/N, contact Siemens Service.