Background: MRI 7T UHF (Ultra High Field) has been around for many years as a research tool before it was introduced as an advance imaging technology for humans in 1999. The first MRI 7T was approved by the Food and Drugs Administration in October 12, 2017 for clinical use after research testing on the equipment safety and compatibility. The advancement of MRI 7T has led to higher image spatial resolution, thinner slices, and tissue contrast differentiation of various anatomical structures. The most common imaging exams performed at 7T are done on clinical epilepsy patients for detecting, localizing, and characterizing potential seizure-causing lesions such as focal cortical dysplasia. In addition, the advantage of 7T in research imaging is outstanding for neuro functional, MR Spectroscopy, CSF flow, knee imaging, and new sequence optimization for both human and preclinical studies. Equipment: The 7T Siemens Magnetom Terra (Siemens Medical Solutions, Inc) with software VE12U has 60 cm bore, table length 234 cm, magnet length 270 cm, weight 25 tons, and with passive and active shimming. The coils that can be used with clinical mode consist of head 1TX/32RX, head sodium 23Na 1TX/32RX, knee TX/RX 28 channels, and small flex loop 1H TX/RX surface coil. The head coils weigh about 30 pounds, which require carrying with precaution or with two people. The knee coil is light and easy for one person to lift. The MRI table cannot be undocked from the scanner and does not have hydraulics to move the table up and down, causing some difficulty for patients.
Figure 1: MRI 7T Siemens Magnetom Terra
MRI 7T Magnetic Field Effects Preparation: With the stronger magnetic field at 7T, the static magnetic effect is a safety consideration for patient and operator. The patient needs to be aware of the static magnetic field effects that cause a temporary imbalance of the vestibular system in which they may feel vertigo, dizziness, nausea, and nystagmus when the table is moving the head inside scanner bore. The side effect symptoms can vary from light to severe depending on patient sensitivity. Technologists operating the 7T may feel vertigo, walking imbalance, and metallic taste as they approach the scanner bore. He/she needs to walk slowly inside the 7T scanner room while taking care of patients. All patient preparation instructions for 7T exams should be done outside the scanner room to limit the time spent near the magnetic field.
Patient Safety Preparation: The higher magnetic field causes higher SAR values than for lower field strengths, particularly for spin-echo sequences. In addition, 7T has a strong angle of defection and pulling force on objects, and higher RF deposition in the body. Additional safety screening is necessary for the patient with any passive and active implants prior to undergoing a 7T exam. With a conservative approach, patients with active implants not tested for 7T should not be scanned at this field strength. Also, most of the passive implants that are MR safe and conditional at 3T are also considered conditional at 7T, such as spinal fixation devices, orthopedic, and dental implants that are made of titanium, aluminum, platinum, gold, and silver materials. Vascular implants such as stents, coils, filters or aneurysm clips that are conditional at 3T will need additional approval by a radiologist prior to 7T imaging, generally excluded if the implant is within the transmit RF coil range, for example at the shoulders and above for neuroimaging with a head coil.
Summary: Operating at 7T is very similar to operating other standard clinical 1.5T and 3T MRI scanners. Nevertheless, the operator of 7T should be well trained and understand the MRI environment. Safety related to the patient, equipment, and implants is critical for the technologist to master, prior to taking care of patient in the 7T environment.

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