Postoperative Susceptibility Artifact During Magnetic Resonance Imaging of the Vertebral Column in Two Dogs and a Cat

Abstract

In humans that have undergone cervical diskectomy, magnetic susceptibility artifacts are often found on postoperative magnetic resonance (MR) images of the affected region. In some patients, these artifacts complicate image interpretation, while in others the artifacts lead to a false diagnosis of spinal cord compression. We describe two dogs and one cat that had susceptibility artifacts visible in postoperative MR images. In each patient, multiple, small-to-large, distinct, magnetic susceptibility artifacts were visible along the surgery site. In both dogs, interpretation was impossible and subsequently computed tomography (CT) was performed. During CT, no cause for the MR artifact was identified. The most likely source of the artifact is microscopic metal fragments from the burr, suction tip or other surgical instruments, but other possible causes include hemorrhage or paramagnetic suture material. These artifacts may cause difficulty in interpretation or suggest a clinical problem. MR imaging therefore might not be the most appropriate examination for patients following certain types of surgery due to the possibility of susceptibility artifacts. Although this artifact probably is common in the postoperative patient, the frequency that this finding will prevent accurate diagnosis is unknown.

Evaluation of the Susceptibility Artifacts and Tissue Injury Caused by Implanted Microchips in Dogs on 1.5T Magnetic Resonance Imaging

“…A recent scientific article described magnetic susceptibility artifacts seen on 0.2 T MRI in animals after vertebral surgery [2]. Microscopic metal fragments from the surgical burr, suction tip, or other surgical instruments were thought to be the most likely source of artifacts in this report.…”

“…The artifact area as a percentage of the cervical area was 67% for the maximum (T2*WI, dorsal) and 15% for the minimum (PDWI, transverse). The estimated entire artifact area was calculated as 158 cm 2 for the maximum (T2*WI, transverse) and 32 cm 2 for the minimum (PDWI, sagittal). All sequences had at least one image where the artifact extended over the spinal cord.…”

“…There are a few publications describing magnetic susceptibility artifacts in MR images in veterinary medicine [2,3,10]. A recent scientific article described magnetic susceptibility artifacts seen on 0.2 T MRI in animals after vertebral surgery [2].…”

“…A typical susceptibility artifact on MRI is characterized as a central signal loss and image distortion with a rim of increased signal intensity around the vicinity of the magnetic substance or near junctions between tissues of differing magnetic susceptibility [2,3,5,18]. A rim of increased signal intensity is not apparent when in the presence of a stronger ferromagnetism [9,11].…”

Evaluation of intraorbital prosthetic pigmentation using 0.3 and 1.5Tesla magnetic resonance imaging and computed tomography

“…Various publications have reported advanced imaging susceptibility artifacts as well as techniques to reduce these artifacts . In a recent case report, a brown‐pigmented intraorbital prosthetic caused a significant susceptibility artifact on MR images that precluded adequate visualization of intracranial structures in a patient with neurologic disease .…”