Can I take Lorazepam (Ativan) when undergoing a Positron Emission Tomography (PET) scan?

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From the Guidelines

You should not take lorazepam before a PET scan without consulting your healthcare provider, as it may interfere with the scan results, particularly for scans measuring brain activity, according to the most recent guidelines 1. When considering taking lorazepam for a PET scan, it's essential to weigh the potential benefits of anxiety relief against the possible impacts on scan accuracy.

Key Considerations

  • The European Journal of Nuclear Medicine and Molecular Imaging guidelines suggest that regular use of sedatives, such as short-acting benzodiazepines, in adult patients is not recommended 1.
  • However, if you have anxiety about the procedure, your doctor might approve a small dose of lorazepam to help you remain still during the scan, which is crucial for clear images.
  • The timing of taking lorazepam matters, as taking it shortly before the scan might have different effects than taking it hours earlier.
  • It's also important to inform the radiology team about any medications you've taken, as they may need to account for this when interpreting your results.

Patient Preparation

  • Patients should abstain from eating any food, simple sugars, or beverages, except for plain water, for a minimum of 4 hours prior to the commencement of the PET/CT scan 1.
  • Coffee or caffeinated beverages are not recommended, as they may contain traces of simple carbohydrates and have the potential to induce excitant effects 1.
  • Patients should void immediately prior to the PET/CT examination to reduce bladder activity 1.

Conclusion is not allowed, so the answer will be ended here, but the most important information is that the patient should consult with the healthcare provider before taking any medication.

From the Research

Lorazepam and PET Scan Interactions

  • The use of benzodiazepines, such as lorazepam, before undergoing a Positron Emission Tomography (PET) scan has been studied to determine its effects on the efficacy of the scan 2.
  • One study found that the administration of benzodiazepines does not decrease the efficacy of the PET scan, and the maximum standardized uptake values (SUVs) were not significantly different between patients who received benzodiazepines and those who did not 2.
  • However, another study found that the administration of diazepam, a benzodiazepine, caused a significant reduction in global FDG uptake in the rat brain, but did not change local patterns within the brain 3.
  • In terms of anxiety reduction, benzodiazepines such as lorazepam have been found to be effective in reducing anxiety in patients undergoing medical imaging procedures, including PET scans 4.
  • The neurochemical effects of lorazepam have also been studied, and it has been found to affect the metabolism of dopamine and 5-hydroxy tryptamine (5-HT) in the brain 5.
  • A study on generalized anxiety disorder found that benzodiazepine therapy resulted in decreases in absolute metabolic rates for cortical surface, limbic system, and basal ganglia, but was not associated with normalization of patterns of glucose metabolism 6.

Key Findings

  • Benzodiazepines do not adversely affect the efficacy of PET scans 2.
  • Diazepam reduces global FDG uptake in the rat brain, but does not change local patterns within the brain 3.
  • Lorazepam affects the metabolism of dopamine and 5-HT in the brain 5.
  • Benzodiazepines can reduce anxiety in patients undergoing medical imaging procedures, including PET scans 4.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Use of benzodiazepines before (18)F-FDG-PET/CT dual-phase imaging does not decrease the efficacy of the study.

Indian journal of nuclear medicine : IJNM : the official journal of the Society of Nuclear Medicine, India, 2012

Research

Neurochemical and behavioral effects of lorazepam: A dose related study.

Pakistan journal of pharmaceutical sciences, 2021

Research

PET in generalized anxiety disorder.

Biological psychiatry, 1991

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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