A pilot trial on kinematic magnetic resonance imaging using a superconducting, horizontally opened, 1.2 T magnetic resonance system

Abstract

Purpose: This study was performed to introduce and evaluate the potential of kinematic magnetic resonance imaging (KMRI) using a high-field open-magnet magnetic resonance (MR) system.

Methods: We attempted to perform KMRI of healthy volunteers' lumbar spine and knee in the lateral position and ankle in the supine position utilizing the superconducting, horizontally opened, 1.2 T MR system (OASIS, HITACHI, Tokyo, Japan). For the KMRI of the lumbar spine, the volunteer had to lie on one side while maintaining maximally anteflexed, neutral, and maximally retroflexed positions and remain still for the duration of the acquisition time for each posture. In the same way, KMRI of the knee was performed with the volunteer's knee flexed at 0°, 30°, 60°, 90°, and 120° in the lateral position, and KMRI of the ankle was performed with the volunteer's ankle in maximally dorsiflexed, neutral, and maximally plantarflexed positions while lying in the supine position.

Results: We could acquire higher quality kinematic MR images than those acquired using low-field MR systems. The spinal canal, intervertebral discs and foramina, and facet joints in lumbar spine KMRI; the ligaments, menisci and patellofemoral joint in knee KMRI; and the tibiotalar articulation and peroneal tendon in ankle KMRI were clearly depicted.

Conclusion: The results of our pilot trial indicated that a superconducting horizontally opened, 1.2 T MR system offers high-quality KMRI images and can be utilized for the kinematic diagnosis and evaluation of sports injuries.

Keywords: Joint Motion; KMRI; Kinematic; Magnetic Resonance Imaging; Open MRI.

Fig. 1

The configuration of two types of magnetic resonance systems: (a) the superconducting, horizontally opened, 1.2 T magnetic resonance system and (b) the conventional tunnel-type, bored 1.5 T magnetic resonance system.

Fig. 2

The postures in kinematic magnetic resonance imaging of the lumbar spine: (a) maximally anteflexed, (b) neutral, and (c) maximally retroflexed positions. A solenoid receiving coil was put on the subject's back (arrow).

Fig. 3

The posture in kinematic magnetic resonance imaging of the knee. (a) The fixation of the knee by a supporting tool (CHAMCO, Inc., Cocoa, Florida, USA) and the arrangement of the solenoid receiving coil (arrow) are shown. The knee flexion can be adjusted from 0° to 120°. (b) The subject's position during the image acquisition is shown.

Fig. 4

The posture in kinematic magnetic resonance imaging of the ankle. (a) The fixation of the ankle by a supporting tool (CHAMCO, Inc., Cocoa, Florida, USA) and the arrangement of the solenoid receiving coil (arrow) are shown. (b) The subject's position during the image acquisition is shown.

Fig. 5

Example of kinematic magnetic resonance images of the lumbar spine. Upper row: slices at the middle plane of the vertebral body. Lower row: slices at the level of the intervertebral foramen. Each of them is arranged from left to right in order of maximal anteflexion, neutral, and maximal retroflexion positions.

Fig. 6

Example of kinematic magnetic resonance images of the knee. Upper row: slices at the level of the anterior cruciate ligament (ACL). Middle row: slices at the level of the posterior cruciate ligament (PCL). Lower row: slices at the level of the medial meniscus (MM). The angle indicated at the lower left of each image is the flexion angle of the knee.

Fig. 7

Example of kinematic magnetic resonance images of the ankle. Upper row: slices at the central trochlea of the talus (TT). Lower row: slices at the level of the peroneal tendon (PT). Each of them is arranged in order from left to right of maximal dorsiflexion, neutral, and maximal plantarflexion positions.