Motion Artifacts in SPECT Myocardial Perfusion Imaging

Directions to the Patient

Provide the patient with a detailed description of the procedure, emphasizing the importance of not speaking or moving any part of the body during image acquisition.

Explain the scan’s importance in managing their CAD or suspected CAD. A well-informed patient is more likely to cooperate and tolerate any discomfort during imaging.

Emphasize the importance of staying awake during the scan because falling asleep can cause a change in the breathing pattern and consequently change the movement of the chest and heart motion. Also, explain that motion may be further exaggerated during sleeping if the patient snores, gasps, twitches, or inadvertently moves.

In casual conversation, determine if the patient is a singer. Although this sounds like an unusual topic of conversation, another breathing artifact may be encountered if the patient is a singer. Some singers are taught to breathe from their diaphragm to help them improve their breath support, resonance, and vocal control (6). This deep belly breathing can cause exaggerated motion in the chest. If possible, practice with the patient to encourage them to breathe normally and avoid deep belly breathing.

Patient Comfort

Take the time to ensure the patient’s comfort by utilizing support pillows under the knees, shoulder, arms, etc.; utilizing straps that may be used to support stiff arms or shoulders; and providing a warm blanket or no blanket as desired.

Additional Suggestions

Assess the patient for claustrophobia or anxiety to determine whether additional preparation is required before and during imaging. Before imaging, the patient may benefit from a “trial run.” Allow the patient to lie on the imaging table and experience the required body position and camera motion during acquisition. This trial run can be performed either before the start of the exam or days before the procedure. If the patient finds that the scan is intolerable, then contact with the referring physician may be required to obtain antianxiety medication on the day of the procedure. If the patient has been provided with antianxiety medication, the technologist should ensure that the appropriate dosing times correspond with both imaging times—rest and stress imaging.

Additional suggestions to support an anxious or claustrophobic patient include the following: (1) Keep as much of the patient’s head outside the scanner. An anxious patient will usually tolerate the scan better if the detectors are not directly over their head. However, the technologist must ensure enough of the chest is under the scanner to maintain the heart in the field of view. (2) Give the patient a verbal countdown to the scan’s end whenever possible. Turning the p-scope so the patient can see the scan duration timeline live on the monitor may also be beneficial. (3) Adjust the lights, covering the patient’s eyes, and/or providing music may also be beneficial in providing the patient with a calming environment to minimize anxiety and discomfort. (4) Eliminate the safety straps that may make some patients anxious; however, the technologist must be vigilant to ensure the patient does not move or is injured by falling off the table. (5) Have the technologist or a family member (preferred) support the patient by talking to them or holding their hand if CT is not performed during the procedure; however, the patient should understand that they must not speak or turn their head, which may introduce motion in the image. (6) Utilize prone imaging to help reduce the patient’s anxiety. This way the camera heads are not directly over the patient’s face. However, prone imaging can introduce additional artifacts and may make gating difficult. (7) Use upright imaging cameras, when available (e.g., Digirad Inc., CardiArc Ltd.), or semiupright cameras (D-SPECT, Spectrum Dynamics) which can significantly alleviate a patient’s anxiety as the patient is seated or semireclined and the detector is positioned at the chest rather than over the patient’s face. For the upright imaging cameras, the arms comfortably rest on the unit’s armrest, alleviating the need for the patient to stabilize the weight of their arm overhead. However, motion can still be noted with these upright imaging systems. The patients tend to sit up straight at the start of the imaging procedure, and as the scan proceeds, they may relax and slump down in the imaging chair. This motion can introduce an artifact into the image. One suggestion to avoid this slumping motion, after positioning the patient for imaging, is for the technologist to run both hands over the back of the patient’s neck and shoulders while encouraging the patient to relax. In this manner, the patient will be resting at the start of the exam and less likely to introduce motion by slumping down.