Combined dose-reduction strategies may reduce contrast use by 80%
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By combining dose-reduction strategies, investigators found IV contrast use for CT scans could be reduced by approximately 80%.
“Contrast is essential in any situation where we need to assess the blood vessels — for example, for some trauma patients or those with a suspected acute gastrointestinal bleed — and it is also needed for evaluation of certain cancers, such as in the liver or pancreas,” Rebecca Smith-Bindman, MD, senior study author and professor in the department of epidemiology and biostatistics at the University of California San Francisco, said in a press release. “However, most CT scans are done for less specific indications, such as abdominal pain in a patient with suspected appendicitis. These can and should be done without contrast during the shortage, because the loss of information in these patients will be acceptable for most patients.”
Smith-Bindman and colleagues created models that used five alternative strategies for conserving contrast during CT imaging, including weight-based dosing (model A), reducing contrast dose while reducing tube voltage (model B), replacing contrast CT with unenhanced CT if the American College of Radiology Appropriateness Criteria predicted no more than moderate negative effect on diagnostic accuracy (model C), a combination of models A and C (model D) and a combination of models A, B and C (model E). Researchers estimated the total expected contrast use at baseline and in each of the five hypothetical strategies by applying the rules of each contrast-conserving strategy to observed contrast use in a sample of 1.04 million CT examinations in the University of California San Francisco International CT Dose Registry performed Jan. 1, 2015, to March 11, 2021.
Results showed an estimated 47.1 million mL of contrast was used for the 1 million CT scans in the base case. Researchers found contrast use would be reduced by 12% and 25% with weight-based dosing and by reducing tube voltage and contrast dose, respectively. Use of unenhanced CT instead of contrast-enhanced CT when moderate reduction in diagnostic accuracy is acceptable had the greatest reduction in contrast use by 78%, according to results. Researchers estimated an 83% reduction in contrast use when all three approaches were combined.
“Given the acute shortage, it’s important that clinicians who order imaging exams coordinate with radiology to cancel scans that aren’t absolutely necessary, postpone exams that can be safely delayed, replace CT with MRI and ultrasound where possible and order an unenhanced scan where possible,” Smith-Bindman said in the release. “Further, clinicians should communicate with their patients about why this is necessary. It is crucial that contrast be conserved for clinical situations where its use is essential for accurate diagnosis.”
References
Amid global shortage, study shows how to cut contrast dye use 83%. https://www.ucsf.edu/news/2022/06/423086/amid-global-shortage-study-shows-how-cut-contrast-dye-use-83#:~:text=June%209%2C%202022-,Amid%20Global%20Shortage%2C%20Study%20Shows%20How,Cut%20Contrast%20Dye%20Use%2083%25&text=As%20a%20worldwide%20shortage%20of,)%20by%20up%20to%2083%25. Published June 9, 2022. Accessed June 22, 2022.
Davenport MS, et al. JAMA. 2022;doi:10.1001/jama.2022.9879.
Perspective
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A recent severe shortage of iodinated contrast media found many radiology departments unprepared. While often “transparent” to our referring physicians, iodinated contrast media is essential for diagnosis and management of many serious and life-threatening diseases, including pulmonary embolism, arteriography, intervention for central and peripheral thromboembolic disease, renal obstruction and cancers. The shortage is attributed to the quarantine and closure of GE Healthcare’s iodinated contrast media facility in Shanghai, and, in April 2022, GE Healthcare notified clients of rationing. GE Healthcare has shifted production to mitigate the crisis.
The JAMA research letter compares three models and two combined models for contrast conservation using a hypothetical population of 1 million CT scans calculating reductions in contrast use for each. Performing unenhanced instead of enhanced CT for nonessential, non-vascular conditions showed the best single strategy reduction (78%). The two combination strategies using unenhanced CT plus weight dosing (80%) and weight-based dosing plus reduced kilovolt X-ray energy plus reduced contrast dose (83%) demonstrated slightly better overall dose reductions. At our institution, we used unenhanced CT, alternative studies (MRI) and eliminated iodinated contrast media for MRI arthrograms. This crisis serves as a reminder that our medical resources are fragile, and we must remain aware, adaptable and resourceful.
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