Unlocking Adrenal Vein Sampling Success: How CT Mapping Can Help
"Can a simple CT scan before adrenal vein sampling (AVS) really boost your chances of a successful diagnosis? Here's what the latest research reveals about using CT mapping to pinpoint those tricky adrenal veins."
If you've been diagnosed with primary aldosteronism (PA), you're likely familiar with the challenges of managing hypertension, and the quest for an accurate diagnosis. Adrenal vein sampling (AVS) is a critical step in determining the underlying cause of PA, but it's far from a walk in the park. The procedure is technically demanding, and success rates can vary significantly, leaving many patients and doctors frustrated.
For years, AVS has been the gold standard for differentiating between the two main causes of PA: an aldosterone-producing adenoma (a benign tumor on one adrenal gland) or bilateral adrenal hyperplasia (overactivity of both adrenal glands). Knowing the precise cause is essential because it dictates treatment – surgery for an adenoma versus medication for hyperplasia.
Now, a new approach is gaining traction: using detailed CT scans to map the adrenal veins before AVS. This technique, known as CT mapping, aims to provide interventional radiologists with a precise roadmap, making the procedure faster, easier, and more successful. But how effective is it, and is it ready for widespread adoption? Let's dive into the details.
AVS Success and Anatomy
Adrenal venous sampling (AVS) is described as the gold standard for identifying aldosterone-producing adenoma and bilateral adrenal hyperplasia. A May 2026 study specifically evaluated AVS success rates and the distribution of the right adrenal vein orifice. Recent imaging advances and improved knowledge of adrenal vein anatomy have made AVS easier to perform, although anatomic variants can still cause sampling failure or misinterpretation.
Standardization Challenges
AVS remains the standard method for subtype diagnosis in primary aldosteronism, but the methods used to sample the adrenal veins are not standardized. Catheterization requires attention to adrenal venous anatomy and its variants, and technical difficulties can affect both sample collection and interpretation. The literature therefore emphasizes detailed procedural review, while also recognizing limitations in available resources, facilities, and newer alternatives to AVS.
From Proposal to Standard
Adrenal vein sampling was first proposed and shown to be a reliable diagnostic test for localizing hyperaldosteronism in the 1960s by James Melby and colleagues at Boston University School of Medicine. Reported technical success rates have varied widely, from 40% to more than 90%. The most common reported failure is inability to select or correctly identify the right adrenal vein, while a cortisol gradient between an adrenal vein sample and the inferior vena cava or a peripheral vein is used as a proxy for correct catheter placement.
Why is Adrenal Vein Sampling So Darn Difficult?
Before we explore the potential of CT mapping, it's important to understand why AVS is so challenging in the first place. The adrenal veins, especially the right one, are small and variable in their anatomy. This is especially true for the right adrenal vein (RAV), which is shorter, smaller, and tends to drain directly into the inferior vena cava (IVC). Finding and cannulating the RAV can feel like searching for a needle in a haystack.
- Small Size: Adrenal veins, particularly the RAV, are tiny, often only 2-3 mm in diameter.
- Variable Anatomy: The exact location and drainage pattern of the RAV can vary significantly from person to person.
- Technical Skill: Successfully navigating and cannulating these small veins requires a high degree of skill and experience on the part of the interventional radiologist.
CT Mapping in Difficult Cases
A 2025 case report found that intraoperative 4D-CT angiography from the right adrenal artery can increase AVS success, particularly when the right adrenal vein is invisible on preoperative CT. Another study reviewed 4D CT images from 55 patients who underwent AVS between August 2017 and February 2021, including 23 women with a mean age of 52 years. Multidetector CT mapping has also been used before AVS to guide catheter selection, manipulation, and occasional steam shaping, with one institution reporting a 99% right-sided AVS success rate.
Why AVS Still Fails
An expert consensus statement reported that AVS remains markedly underused despite guideline recommendations for identifying surgically curable causes of hyperaldosteronism. Perceived technical difficulty, challenges in interpretation, and the possibility of adrenal vein rupture were identified as factors contributing to limited use. A separate failure-mode analysis examined 343 AVS procedures performed over 10 years in a high-volume practice to identify preventable causes of nondiagnostic sampling.
Comparing Sampling Approaches
A 2025 study compared three approaches for bilateral AVS and examined their feasibility, safety, and influence on adrenalectomy outcomes in patients with dominant lateral primary aldosteronism. The study included 182 patients treated at Fuwai Hospital between January 2022 and March 2024. Other recent work notes that AVS remains the standard for subtype diagnosis even though the methods used to sample the adrenal veins are not standardized.
The Verdict: Is CT Mapping Worth It?
While this study offers promising evidence, it's important to remember that it's just one piece of the puzzle. More research is needed to definitively prove that CT mapping improves AVS success rates, reduces complications, and ultimately leads to better outcomes for patients with primary aldosteronism. However, the initial results are encouraging, and CT mapping may soon become a standard part of the AVS procedure, helping more patients receive an accurate diagnosis and the right treatment.
Expertise and Consistency
An international expert panel issued updated advice on how to perform and interpret AVS because the procedure lacks uniformly accepted standards. A review of current practice highlights variability among institutional protocols, a shortage of interventional radiologists trained in AVS, and technical pitfalls that can affect success. Together, these sources support improving procedural consistency and specialist expertise rather than treating AVS as a uniformly standardized test.
Beyond Imaging Alone
CT or MRI cannot reliably distinguish unilateral from bilateral disease in primary aldosteronism, making AVS an important part of the diagnostic work-up. Current guidelines recommend AVS for virtually all patients with biochemically diagnosed primary aldosteronism who would undergo adrenal surgery if unilateral disease were found. Although AVS is considered the most reliable method for determining whether hormone production is unilateral or bilateral, sampling can be nondiagnostic when the vein cannot be properly cannulated.
Outcomes in Practice
A 2021 systematic review references a retrospective cohort study examining clinical outcomes of primary aldosteronism according to the lateralization index and contralateral suppression index after AVS. This focus reflects how AVS interpretation can influence the assessment of patients in real-world practice. The provided source identifies the study topic but does not report its specific cohort size or outcome figures.