Indication and technical aspects of adrenal blood sampling

Diagnostic Impact of Adrenal Vein Sampling in Adrenal Cushing's Syndrome

BACKGROUND

Adrenal Cushing's syndrome is characterized by ACTH-independent hypercortisolism. Adrenal vein sampling (AVS) is not routinely employed prior to management decisions, and few studies have investigated the value of AVS in this population. We assessed whether AVS provides a diagnostic benefit for treatment planning.

MATERIALS AND METHODS

Six patients with imaging and biochemical evidence of adrenal Cushing's syndrome undergoing AVS at our institution from 2015 to 2020 were analyzed retrospectively, including demographic and clinical characteristics. AVS lateralization index was determined by comparing the (cortisol/ipsilateral reference hormone) ratios of both adrenal veins. lateralization index of 2 or greater was considered diagnostic of unilateral disease. Post-management clinical improvement was defined as serum cortisol normalization, symptomatic improvement, or both.

RESULTS

Cross-sectional imaging noted bilateral adrenal enlargement or nodules in three patients, and unilateral nodules in three patients. AVS results were discordant with imaging in three patients. Treatment included medical management in two patients, percutaneous radiofrequency ablation in one patient, and laparoscopic adrenalectomy in two patients. One patient was lost to follow up. AVS results aided management planning in five patients, definitively changing treatment from surgery to medical management in one patient. All five patients demonstrated clinical improvement.

CONCLUSIONS

AVS offered useful information for determining appropriate management of adrenal Cushing's syndrome, especially distinguishing unilateral from bilateral disease. Even in bilateral disease, AVS may show a dominant gland, potentially allowing a staged unilateral adrenalectomy, before assessing the need for completion adrenalectomy or medical management. Larger studies are needed to better establish whether AVS offers significant benefit for this population.

Adrenal venous sampling in primary hyperaldosteronism: correlation of hormone indices and collimated C-arm CT findings

PURPOSE

To evaluate the feasibility and effect of an approach to adrenal venous sampling (AVS) analysis by combining established selective cortisol and aldosterone indices with the acquisition of a collimated C-arm CT(CACT_Coll).

METHODS

Overall, 107 consecutive patients (45f,62 m; 54 ± 10 years) undergoing 111 AVS procedures without hormonal stimulation from 7/13 to 2/20 in a single institution were retrospectively analysed. Hormone levels were measured in sequential samples of the suspected adrenal veins and right iliac vein, and selectivity indices (SI) computed. Stand-alone SI_Cortisol and/or SI_Aldosterone ≥ 2.0 as well as SI_Cortisol and/or SI_Aldosterone ≥ 1.1 combined with positive right-sided CACT_Coll of the adrenals (n = 80; opacified right adrenal vein) were defined as a successful AVS procedure. Radiation exposure of CACT was measured via dose area product (DAP) and weighed against an age-/weight-matched cohort (n = 66).

RESULTS

Preliminary success rates (SI_Cortisol and/or SI_Aldosterone ≥ 2.0) were 99.1% (left) and 72.1% (right). These could be significantly increased to a 90.1% success rate on the right, by combining an adjusted SI of 1.1 with a positive CACT_Coll proving the correct sampling position. Sensitivity for stand-alone collimated CACT (CACT_Coll) was 0.93, with 74/80 acquired CACT_Coll confirming selective cannulation by adrenal vein enhancement. Mean DAP_{Coll_CACT} measured 2414 ± 958 μGyxm², while mean DAP_{Full-FOV_CACT} in the matched cohort measured 8766 ± 1956 μGyxm² (p < 0.001).

CONCLUSION

Collimated CACT in AVS procedures is feasible and leads to a significant increase in success rates of (right-sided) selective cannulation and may in combination with adapted hormone indices, offer a successful alternative to previously published AVS analysis algorithms with lower radiation exposure compared to a full-FOV CACT.

Interventional radiology of the adrenal glands: current status

As more and more adrenal neoplasms are found incidentally or symptomatically, the need for interventional procedures has being increasing. In recent years these procedures registered continued steady expansion. Interventional radiology of the adrenal glands comprises angiographic and percutaneous procedures. They may be applied both in benign and in malignant pathologies. The present review reports the current status of indications, techniques results and complications of the image-guided procedures.

Abnormal gel flotation caused by contrast media during adrenal vein sampling

INTRODUCTION

During adrenal venous sampling (AVS) procedure, radiologists administer a contrast agent via the catheter to visualize the proper catheter position.

MATERIALS AND METHODS

A patient with primary aldosteronism diagnostic-hypothesis was admitted for AVS. A venogram was performed to
confirm the catheter's position with 2mL of Iopamidol 300 mg/mL. Samples were collected with syringe connected to a hydrophilic coated catheter by low-pressure aspiration from each of the four collection sites: inferior vena cava in the suprarenal portion, inferior vena cava in the infrarenal portion, left adrenal vein, and right adrenal vein; then immediately transferred from syringe to tubes with gel separator. All tubes were centrifuged at 1200 x g for 10 minutes.

RESULTS

At the end of centrifugation process, primary blood tubes containing blood from inferior vena cava and left adrenal vein exhibited the standard gel separator barrier, while tubes from right adrenal vein showed abnormal flotation of gel separator. The radiologist confirmed the usage of 2.6 mL instead of 2.0 mL of Iopamidol 300 mg/mL. This iodinated contrast media, with 1.33 g/cm3 of density, was used close to the right adrenal vein due to some difficulty to access it.

CONCLUSION

The abnormal flotation of gel separator in samples taken from right adrenal vein can be explained by the usage of the iodinated
contrast media. We suggest using plain-tubes (without gel separator) for AVS in order to avoid preanalytical nonconformities. Moreover, a blood volume equivalent to twice the catheter extension should be discarded to eliminate residual contrast media before collection of samples for laboratory assays.