A lung scan is a general term for various medical imaging tests used to visualize the lungs, blood vessels, and surrounding structures within the chest. These procedures help physicians diagnose conditions like infections, tumors, or blockages in pulmonary blood flow. The total time a patient spends at the facility varies significantly, depending on the specific imaging technology ordered. While the image acquisition itself is often fast, the overall appointment involves multiple steps that extend the length of the visit considerably.
Preparing for the Scan
Preparation often accounts for a substantial portion of the overall appointment duration. Patients are typically advised to arrive 15 to 30 minutes before their scheduled time to complete paperwork and check-in procedures. Once registered, the patient usually changes into a hospital gown and removes any metal items, such as jewelry or clothing with zippers, which can interfere with the imaging equipment. This initial preparation ensures the clarity of the resulting images.
If the scan requires intravenous (IV) contrast dye, the preparation time lengthens due to additional requirements. For contrast-enhanced Computed Tomography (CT) or Positron Emission Tomography (PET) scans, patients are often instructed to fast for four to six hours beforehand, consuming only water. A blood test, typically for creatinine levels, may be performed to ensure the kidneys can safely process the contrast agent. A technologist will then place an IV line in the arm or hand, which adds to the pre-scan timeline.
Preparation for a Ventilation/Perfusion (V/Q) scan is generally simpler, without fasting requirements, though patients may need a recent chest X-ray for comparison. These pre-procedure steps, from arrival to being positioned on the scanner table, collectively add anywhere from 20 to 45 minutes to the total visit time.
Understanding the Procedure Duration
The time spent inside the scanning room differs based on the technology used. The quickest procedure is typically a low-dose CT scan, where image acquisition often takes less than 60 seconds. For a standard chest CT scan, with or without contrast, the patient is on the table for about 5 to 15 minutes. During this time, the table slides through the machine while the patient is asked to hold their breath for short intervals, usually 10 to 12 seconds, to prevent motion blur.
A V/Q scan assesses both airflow and blood flow in the lungs and is a two-part procedure typically taking between 30 and 60 minutes. The first part involves the patient breathing a small amount of radioactive gas through a mouthpiece while a camera images the air distribution. The second part requires an injection of a different radioactive tracer, followed by another set of images to map the blood flow, with the patient lying still throughout the scan.
The longest lung imaging procedure is the PET/CT scan, often used to assess cellular activity, such as in cancer staging. The total time for a PET/CT appointment can span two to three hours. This duration is due to the radioactive tracer, which is injected intravenously and needs time to distribute and be absorbed by the tissues. This uptake period requires the patient to rest quietly for 60 to 90 minutes before the actual scan begins. Once the tracer has accumulated, the combined PET and CT imaging takes approximately 20 to 30 minutes to complete.
Post-Scan Logistics
After image acquisition is complete, the technologist performs immediate post-scan checks, reviewing the images on a computer screen for quality and completeness. If an IV line was placed for contrast or a radioactive tracer, it will be removed by the technologist at this time.
Patients who received an IV contrast agent are encouraged to drink plenty of fluids for the next 24 hours to help flush the contrast material from their system. Unless a sedative was given, there is usually no formal recovery period, and patients can immediately resume normal activities. They can then retrieve their belongings, change back into their clothing, and be discharged from the imaging facility.
The final logistical step is the timeline for receiving the results, which involves a radiologist interpreting the images and generating a formal report. For routine scans, this report is typically finalized and sent to the referring physician within 24 to 48 hours. In emergency or urgent cases, preliminary results from a CT scan may be available much sooner, sometimes within a few hours. Patients should always contact the doctor who ordered the lung scan to discuss the findings, as the imaging facility only provides the technical report.