A “full body scan” is an umbrella term for comprehensive medical imaging procedures that capture detailed pictures of internal organs and tissues from head to toe. These examinations are typically used for preventative health screening or detailed diagnostic purposes, such as tracking the spread of disease. Because the term encompasses several different technologies, the total time commitment for a full body scan depends highly on the specific imaging modality used.
Pre-Scan Preparation and Logistics
The time commitment for a full body scan begins before the patient enters the imaging machine. Initial administrative tasks, including check-in, reviewing medical history, and changing into a gown, take approximately 15 to 20 minutes. This preparation ensures patient safety and confirms there are no contraindications, such as metal implants for an MRI.
The use of a contrast agent to enhance image quality is a significant factor extending the total appointment length. For Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), intravenous contrast is injected, and scanning begins almost immediately to capture the agent as it circulates. Positron Emission Tomography (PET) scans, however, require a much longer waiting period for the radioactive tracer to distribute.
The PET tracer, typically a glucose analog, requires time to be absorbed by the body’s cells. Following injection, patients must sit quietly for 45 to 90 minutes so the tracer can concentrate in areas of high metabolic activity. This mandatory uptake period ensures the scan accurately captures functional information and significantly contributes to the overall appointment length.
Procedure Duration Based on Imaging Technology
The actual time spent inside the scanner varies substantially depending on whether the procedure uses X-rays, magnetic fields, or radioactive tracers. A full body CT scan is generally the fastest comprehensive imaging modality. The actual scanning time, where the patient moves through the machine, can be as quick as 5 to 15 minutes due to modern CT technology. However, when accounting for positioning and post-scan checks, the total time on the table for a full body CT is often 30 to 45 minutes.
A full body MRI takes considerably longer because the technology relies on collecting multiple signal sequences from hydrogen atoms in water molecules. Since a full-body protocol requires many sequences, the process is lengthy. The actual scanning time for a full body MRI ranges from 30 to 90 minutes, depending on the level of detail required. During this time, the patient must remain completely still to prevent motion from blurring the resulting images.
A PET/CT scan combines functional imaging (PET) with structural imaging (CT), resulting in a variable total procedure time. After the initial 45 to 90-minute tracer uptake period, the patient moves into the hybrid scanner. The actual scan acquisition is usually fast, taking an additional 15 to 30 minutes. The total time from tracer injection to the completion of the scan is often 90 minutes to two hours.
Variables That Can Extend the Total Time
Several patient-specific or technical issues can cause the total appointment time to run longer than standard estimates. Patient motion during the scan is a common issue, as it severely degrades image quality and necessitates a re-scan. If a patient cannot lie still, especially in the enclosed space of an MRI machine, the technologist may need to halt the procedure or spend additional time coaching the patient.
Factors Causing Delays
Patients experiencing claustrophobia or anxiety may require mild sedation, which adds time for medication administration and monitoring. Technical difficulties, such as equipment calibration issues or troubleshooting a contrast injection line, can also introduce unexpected delays. Some diagnostic questions require additional, specialized imaging sequences to be performed on the spot, extending the scan time beyond the initial protocol.