Cannabis use may cause false positives on nuclear imaging scans
Are you emptying your gastrointestinal tract for an imaging scan? You may want to put away the adult gummy bears.
Patients who consume edible cannabis have lower gut motility that can impact the quality of gastric emptying scintigraphy, with a study showing the effect may be more profound than previously thought, given the legalization of the drug and increased consumption of THC products. The research findings are published in the Journal of Nuclear Medicine Technology. [1]
Protocols on gastric emptying have not changed with the times, and physicians may be unaware of just how much cannabis slows the digestive tract. The research team from the Uniformed Services University of the Health Sciences in Maryland said this is concerning, considering nuclear imaging is the go-to method for diagnosing any type of gastrointestinal discomfort.
“Gastric emptying scintigraphy remains the primary imaging modality for evaluating symptoms of gastroparesis such as abdominal pain, bloating, nausea, loss of appetite, and more,” study lead author Rutger Gunther, MD, from the Uniformed Services University of the Health Sciences, said in a statement. “Understanding the effects of cannabis and weight loss drugs on gut motility—that is the movement of food throughout the body—is essential for nuclear medicine providers.”
The relationship between THC in the gut is paradoxical. While the researchers note cannabis has historically been associated with slower gastrointestinal motility, THC can also relieve the symptoms of gastroparesis. Similarly, a review of literature found that gastric emptying is not a problem for those who consume cannabis regularly, with infrequent users tending to see the most slowing of the bowels.
Factors such as the product used, the dosage of THC ingested and a patient’s personal gut microbiome complicate making broad recommendations. However, the researchers said any significant slowing is likely to be relatively short term, and they recommend not consuming cannabis in any form for at least 6 hours before any pre-scan gastric emptying, as there is a risk of a compromised imaging exam that carries a small chance of false-positive findings.
Additionally, there may be interactions between the THC and the “nuclear meal” gastric clearing that are not yet fully understood, with the authors writing that this assumption requires further research.
“More robust double-blinded trials that use the gastric emptying scan procedure standard, test various cannabinoid intake types at different time intervals, and enroll both naïve and chronic users could help clarify the relationship under specific experimental conditions,” the authors wrote. “However, the generalizability of the results would be significantly limited when considering the heterogeneous cannabinoid marketplace accessible to our patients. Instead, studies that assess its clinical utility in symptom management would be of greater utility.”
The authors added that it may be best to recommend all patients not consume cannabis for 72 hours prior to any gastric exam, as there is significant variability and uncertainty in current findings. For now, they recommend physicians conduct a medical history screening that includes asking patients about their cannabis use, and be aware that false-positive findings are possible after any level of consumption.
The full study is available at the link below.
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