From the Research
For patients with a BMI over 35 undergoing a Lexiscan myocardial perfusion imaging (MPI) test, a 2-day protocol is recommended rather than a single-day protocol. This approach involves performing the rest and stress portions of the test on separate days, typically 24-48 hours apart. The 2-day protocol is preferred because higher BMI patients have more soft tissue attenuation, which can reduce image quality and diagnostic accuracy. By separating the rest and stress tests, each scan can be optimized with higher radiotracer doses (typically 25-30 mCi of Tc-99m sestamibi or tetrofosmin for each part) without exceeding radiation safety limits. This results in better count statistics and improved image quality, reducing the likelihood of artifacts and false positive results. Additionally, the 2-day protocol allows technologists to position the patient optimally for each scan and make any necessary adjustments based on the patient's body habitus. Patients should be advised to follow the same preparation instructions for both days, including fasting for 4-6 hours before the test and avoiding caffeine for 24 hours prior to the stress portion.
Some key points to consider:
- Higher BMI patients have more soft tissue attenuation, which can reduce image quality and diagnostic accuracy 1.
- Separating the rest and stress tests allows for optimization of each scan with higher radiotracer doses without exceeding radiation safety limits.
- The 2-day protocol allows technologists to position the patient optimally for each scan and make any necessary adjustments based on the patient's body habitus.
- Patients should be advised to follow the same preparation instructions for both days, including fasting for 4-6 hours before the test and avoiding caffeine for 24 hours prior to the stress portion.
It's worth noting that the provided evidence does not directly address the question of a 2-day Lexiscan MPI protocol for patients with a BMI over 35. However, based on the available information and general principles of medical imaging, the recommended approach is to prioritize a 2-day protocol to ensure optimal image quality and diagnostic accuracy. The most recent and highest quality study on regadenoson, which is the active ingredient in Lexiscan, is from 2020 2, but it does not specifically address the question of a 2-day protocol for high-BMI patients. Nevertheless, the principles of optimizing image quality and reducing artifacts support the recommendation for a 2-day protocol.