Magnetic Resonance Imaging (MRI) uses powerful magnets and radio waves to create detailed images of organs and tissues. Whether a fever necessitates canceling a scheduled MRI is a common question, and the answer depends on multiple factors, including the fever’s severity, its underlying cause, and the specific needs of the scan. A fever usually represents a complication requiring careful consideration by the medical team before the procedure can safely proceed.
The Immediate Protocol: When to Call Your Provider
A fever, defined as a body temperature above the normal range, immediately changes the conditions for a diagnostic scan. The first step is always to notify the facility so staff can relay the information to the physician or radiologist. They will determine if the scan can proceed, needs to be rescheduled, or requires special precautions.
The decision to postpone depends on the fever’s severity and the scan’s urgency. If the fever is mild and the scan is immediately necessary, the medical team might proceed while closely monitoring the patient. However, a high or fluctuating temperature usually leads to postponement because image quality may be compromised. Medical professionals must balance the need for images against potential safety and quality issues.
Medical Reasons Fever Complicates an MRI
The primary reason a fever complicates an MRI is the risk of involuntary patient movement, which severely degrades image quality. A patient with a fever often suffers from discomfort, shivering, or restlessness, making it nearly impossible to remain perfectly still. Movement causes distortions known as motion artifacts, appearing as blurring or “ghosting” on the final image. These artifacts can obscure the pathology the physician is trying to visualize, rendering the scan diagnostically useless.
A secondary concern relates to thermal regulation within the scanner environment. The radiofrequency (RF) pulses deposit a small amount of energy into the body, causing a minor increase in core body temperature. While the scanner monitors this energy deposition through the Specific Absorption Rate (SAR), a patient with a fever may have a reduced capacity to dissipate this extra heat. If the core temperature is high (above 38.5°C or 101.3°F), staff may need to operate the scanner using a conservative, “controlled” mode to prevent overheating. Monitoring a patient compromised by illness is also more challenging within the confined MRI tube, requiring specialized, non-magnetic equipment.
Fever, Infection, and Contrast Agents
A fever is often a sign of acute illness or infection, which introduces specific medical concerns, especially if the scan requires an intravenous contrast agent. These agents, most commonly containing gadolinium, are injected to enhance the visibility of tissues and abnormalities. Gadolinium-based contrast agents (GBCAs) are cleared from the body primarily by the kidneys.
Acute illness, particularly severe infection, can temporarily affect kidney function. If kidney function is compromised, the body may not clear the gadolinium effectively, increasing the risk of complications like nephrogenic systemic fibrosis (NSF) in patients with severe kidney disease. Before administering contrast dye to a patient with a fever, a physician must confirm the patient’s current kidney status by measuring creatinine levels. This ensures the temporary effects of the illness do not put the patient at risk.
The decision is complicated because the fever may be the reason for the scan, such as when a physician is looking for an infection focus like an abscess or osteomyelitis. In these cases, the diagnostic information is highly valuable, and the team may manage the patient’s symptoms by administering fever-reducing medication. Ultimately, the patient’s overall clinical stability overrides the need for the scan. If the fever is part of a severe, systemic infection, the patient’s condition must be stabilized before proceeding with any non-urgent imaging.