Missoula Bone & Joint Clinic has a full-body 1.5 Tesla MR scanner from GE Optima MR360 to perform MRI scans on-site.
What is MRI and how does it produce imaging?
Magnetic resonance imaging (MRI) is a noninvasive medical test that helps physicians diagnose and treat medical conditions. It uses a powerful magnetic field (1.5T), radio frequency pulses, and a computer to produce detailed images without using ionizing radiation (x-rays).
We perform three different types of MRI’s here at Missoula Bone & Joint:
1. A Routine MRI – the images allow physicians to thoroughly evaluate soft tissue structures of the body (muscles, tendons, ligaments, and bones). The most common routine MRI we do at MBJ is the knee. In a knee MRI, physicians can evaluate ACL, MCL, medial and lateral meniscus, patellar tendon, etc. The body part is imaged in at least 3 planes as shown in this knee MRI below and slices (images) are captured through the body part from front to back (frontal), side to side(sagittal), and top to bottom (transverse). This graphic shows the same slice of knee in all 3 planes. The sagittal (middle) image clearly shows the Anterior Cruciate Ligament (ACL).
2. A MRI Arthrogram – this involves a more detailed study of the joint. The most frequent arthrograms performed are of the shoulder and hip because they are both ball and socket joints. These joints are surrounded by a ring of soft tissue, called the labrum. An arthrogram involves two small injections into the joint space performed by our physician, Dr. Rob Amrine. The first injection is Lidocaine to help numb the area and the second injection is Saline and Gadavist (contrast agent). Dr. Amrine uses ultrasound to guide the needle where he needs it in the joint capsule. This contrast agent will highlight on the images and indicate to the physician if there is a labral tear or injury to the joint. After the scan is complete the contrast agent will work its way out of the joint within a few hours.
3. A MRI Contrast Study – this involves enhanced visualization of body tissues and structures. The MRI technologist will start an intravenous (IV) line in the hand or arm before the exam starts. The first portion of the exam is a routine MRI without contrast. About 2/3 of the way through the scan the technologist will inject the contrast through the IV line. The contrast travels through the veins to enhance the area of interest. After the scan the contrast inside the vein will be filtered through the kidneys and gradually released within 72 hours.Below is a sagittal slice from an MRI of a wrist.