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Adrenal vein sampling may expose patients with primary aldosteronism to excess radiation
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Patients with primary aldosteronism undergoing adrenal vein sampling to diagnose disease subtype may be exposed to “fairly high” values of excess radiation, but the amount of radiation exposure varies across centers, according to findings published in the European Journal of Endocrinology.
Adrenal vein sampling (AVS) is often touted as a “gold standard” method to select patients for the surgical management of primary aldosteronism, but its superiority and accuracy is increasingly being challenged for many reasons. As Endocrine Today reported in March, AVS is invasive, expensive and has poor standardization across centers regarding sampling protocols and interpretation of results.
“Another argument brought forward against AVS is the potentially high radiation dose, to which patients are submitted during the procedure,” Carmina Teresa Fuss, of the division of endocrinology and diabetology at University Hospital and University of Wurzburg, Germany, and colleagues wrote in the study background. “Even though there are proven risks linked to radiation exposure, eg, an increased incidence of cancer, to our knowledge there is no available data so far addressing this particular problem.”
Fuss and colleagues analyzed retrospective data from 656 AVS procedures performed between 1999 and 2017 at four university hospitals across Germany, including data on sampling locations and imaging modalities for each center (median age of patients, 53 years; 10 patients underwent AVS twice). Primary outcomes were dose-area product, defined as the product of the radiation dose to air multiplied by the area of X-ray field, and fluoroscopy time, defined as the amount of time during the procedure in which fluoroscopy is used. Researchers approximately calculated consecutively the effective dose.
Researchers found that median dose-area product was 32.5 Gy-cm² and median fluoroscopy time was 18 minutes. Calculated effective dose was 6.4 mSv. However, values between participating centers varied widely, according to the researchers; the median dose-area product ranged from 16 Gy-cm² to 147 Gy-cm², fluoroscopy time ranged from 16 to 27 minutes and effective dose ranged from 3.2 mSv to 29 mSv — the equivalent of 1,470 chest X-rays, according to the researchers.
“For further reference, abdominal CT alone, routinely performed in patients with [primary aldosteronism] to assess the presence of nodules and for visualization of adrenal veins prior to AVS, is associated with an [exposure dose] of approximately 10 mSv,” the researchers wrote.
The researchers also noted the difference in radiation doses between participating centers, which can be explained by the respective variation of imaging modalities. One center, for example, performed less samplings in fewer locations and did not use digital subtraction angiography for the visualization of vascular structure at any point, leading to less radiation exposure.
“To minimize radiation exposure, we recommend adopting some adjustments to currently applied protocols in the future, e.g. by limiting digital subtraction angiography, focusing on a minimum of sampling locations, or limiting the radiation field,” Stefanie Hahner, MD, professor of medicine in the division of endocrinology and diabetology at University Hospital Wurzburg, Germany, told Endocrine Today. “AVS should furthermore be performed by experienced investigators and rapid cortisol measurements during AVS should become standard.”
Hahner noted that non-invasive tools for diagnostic evaluation of primary aldosteronism, including steroidobolomics or functional imaging, represent potential alternatives that are currently evaluated by different groups.
“It will be interesting to see if we will be able to replace AVS by advanced methods,” Hahner said.
– by Regina Schaffer
For more information:
Stefanie Hahner, MD, can be reached at University Hospital Wurzburg, Josef-Schneider-Straße 2, 97080, Wuerzburg Germany; email: Hahner_S@ukw.de.
Disclosures: The authors report no relevant financial disclosures.
Perspective
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The manuscript by Fuss and colleagues is an honest, warts-and-all study of radiation exposure during AVS, from 1999 to 2017, in four different centers. Of these, Munich contributed 400 subjects, and the other three centers a total of 256. Numbers count; Munich had a successful AVS rate of 90%, and the others of 60%, well below what should be expected of a center of excellence. It's not just numbers; in the other centers the dose area product and the effective dose of radiation were three to nine times higher than in Munich (dose area product, 16 Gy-cm²; estimated dose, 3.2 mSv), reflecting equipment and procedural differences, including the use (or not) of rapid cortisol measurement.
For reasons that remain to be explored, bilateral simultaneous over sequential catheterization was associated with a significant increase in radiation exposure. Similarly, the progressive and counterintuitive increase in dose area product in the whole cohort from 2013 through 2017 is shown, but no potential causes canvassed.
The authors' last line of discussion is as follows: "We therefore suggest not only taking this risk into account when referring patients to undergo AVS, but also recommend the establishment and application of a common protocol to reduce and prevent unnecessary exposure to radiation.” The second clause is spot on — the other centers need to do what Munich does. The first should not be read as suggesting patients should forgo AVS; the routine CT scan pre-AVS delivers 10mSv of radiation, and natural background radiation is 2.4 mSv; the 3.2 mSv from AVS at Munich is a trifling addition. AVS is expensive and difficult and demands a highly competent interventionist. It remains clearly superior to CT alone in terms of lateralization, and until steroid fingerprints in peripheral plasma can confidently predict aldosterone producing adenoma vs. bilateral adrenal hyperplasia, it clearly should not be discounted on the basis of radiation danger.
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