Visualization of right adrenal vein: Comparison with three phase dynamic contrast-enhanced CT

Initial experience with adrenal vein sampling using 3D cursor and preprocedural computed tomography (CT) scout image

AIM

To evaluate the success rate and learning curve of adrenal vein sampling (AVS) performed by a single interventional radiologist, using CT scout image marked with a 3D cursor.

MATERIALS AND METHODS

The AVS procedure was conducted on 135 consecutive patients between January 2020 and December 2022 by a single interventional radiologist with no prior experience with AVS. Using a 3D cursor, the positions of the right adrenal vein (RAV), left adrenal vein (LAV), and left renal vein were marked on the CT scout image. AVS procedures were performed based on the marked scout image.

RESULTS

Of 135 AVS procedures, 123 (91.1%) were successful with success rates of 82.1% (23/28), 90.4% (47/52), and 96.4% (53/55) in the first, second, and third years, respectively. Among the 12 failures, 10 occurred on the right side and 2 on the left side. The reasons for failure were failure to locate the RAV (n=5), misidentification of a vessel as the adrenal vein (right, n=4; left, n=1), RAV sample haemolysis (n=1), and the absence of adrenocorticotrophic hormone (ACTH) stimulation (LAV, n=1). Three of the failed cases (misidentified RAV, n=1; sample haemolysis, n=1; and no ACTH stimulation, n=1) underwent repeat AVS, and all were successful.

CONCLUSION

AVS can be successfully performed by an operator without prior AVS experience using a 3D cursor and CT scout imaging. The success rate of AVS increases with the operator experience.

Contrast-enhanced thin-slice abdominal CT with super-resolution deep learning reconstruction technique: evaluation of image quality and visibility of anatomical structures

PURPOSE

To compare image quality and visibility of anatomical structures on contrast-enhanced thin-slice abdominal CT images reconstructed using super-resolution deep learning reconstruction (SR-DLR), deep learning-based reconstruction (DLR), and hybrid iterative reconstruction (HIR) algorithms.

MATERIALS AND METHODS

This retrospective study included 54 consecutive patients who underwent contrast-enhanced abdominal CT. Thin-slice images (0.5 mm thickness) were reconstructed using SR-DLR, DLR, and HIR. Objective image noise and contrast-to-noise ratio (CNR) for liver parenchyma relative to muscle were assessed. Two radiologists independently graded image quality using a 5-point rating scale for image noise, sharpness, artifact/blur, and overall image quality. They also graded the visibility of small vessels, main pancreatic duct, ureters, adrenal glands, and right adrenal vein on a 5-point scale.

RESULTS

SR-DLR yielded significantly lower objective image noise and higher CNR than DLR and HIR (P < .001). The visual scores of SR-DLR for image noise, sharpness, and overall image quality were significantly higher than those of DLR and HIR for both readers (P < .001). Both readers scored significantly higher on SR-DLR than on HIR for visibility for all structures (P < .01), and at least one reader scored significantly higher on SR-DLR than on DLR for visibility for all structures (P < .05).

CONCLUSION

SR-DLR reduced image noise and improved image quality of thin-slice abdominal CT images compared to HIR and DLR. This technique is expected to enable further detailed evaluation of small structures.

High-resolution 0.25 mm Detector CT Has Limited Impact on Right Adrenal Vein Detectability in Preprocedural Contrast Enhanced CT for Adrenal Venous Sampling

OBJECTIVE

This study aims to identify factors associated with the detectability of the right adrenal vein (RAV) on preoperative contrast-enhanced CT scans of adrenal venous sampling (AVS) in the era of high-resolution CT (HRCT).

MATERIALS AND METHODS

In this retrospective study, 36 patients (15 men and 21 women; mean age, 56 y) who underwent preoperative contrast-enhanced CT [11 patients in HRCT with 0.25 mm detector matrix (Cannon Medical Systems) and 25 patients in conventional multidetector CT with 0.5 mm matrix] were included. A contrast agent dose of 600 mgI/kg was injected, and CT images were acquired at a fixed scan delay of 50 and 80 seconds. Adrenal venography and venous sampling were performed for the diagnosis of suspected primary hyperaldosteronism. The qualitative detectability of RAV on preoperative CT was assessed with adrenal venography as a reference. Clinical and imaging factors associated with a good detectability of RAV were analyzed via regression analysis. Optimal acquisition timing was assessed by analyzing the time-intensity curve and contrast enhancement pattern of the inferior vena cava using CT data from a separate cohort (n=5).

RESULTS

The qualitative detectability of RAV was deemed good in 15 patients and poor in 21 patients. Regression analysis revealed that only heterogeneous enhancement of inferior vena cava with bolus high attenuation, corresponding to an optimal acquisition timing from time-intensity curve analysis, was associated with a good detectability of RAV (odds ratio, 5.06). The use of HRCT was not statistically significant.

CONCLUSIONS

Optimal acquisition timing is a crucial factor for the detectability of RAV in preprocedural CT for AVS, while high-resolution 0.25 detector CT appears to have limited significance.

Visualization of Right Adrenal Vein in Non-Contrast-Enhanced MDCT and Its Guiding Role for Right Adrenal Venous Sampling

This study aimed to evaluate the visualization of right adrenal vein (RAV) in non-contrast-enhanced multi-detector computed tomography (MDCT) and its guiding role for right adrenal venous sampling (AVS) in patients with primary aldosteronism (PA). A total of 237 patients diagnosed with PA who underwent successful AVS procedures from January 2020 to March 2021 were retrospectively analyzed. The non-contrast-enhanced MDCT image features of RAV included the degree of visualization and the position of RAV orifice. Subsequently, the concordance degree between RAV in non-contrast-enhanced MDCT and AVS images was calculated to evaluate its guiding effect for right AVS. The visualization rate of RAV in non-contrast-enhanced MDCT was 81.9% (n = 194), with 73.7% (n = 143) clearly displayed and 26.3% (n = 51) generally displayed. In 6.2% (n = 12) of patients who can display RAV, RAV formed a common trunk with the accessory hepatic vein and then merged into the inferior vena cava. Non-contrast-enhanced MDCT revealed that RAV orifice was located between the 10th thoracic vertebra (T10) and the 1st lumbar vertebra (L1), with 85.1% (n = 165) located from the lower 1/3 of T11 to the lower 1/3 of T12. The concordance of imaging anatomy of RAV between non-contrast-enhanced MDCT and AVS image was found to be at a high rate of 94.3% (n = 183). Non-contrast-enhanced MDCT provides excellent visualization of RAV and clearly depicts its anatomical characteristics. Furthermore, RAV images obtained from non-contrast-enhanced MDCT are highly consistent with those from AVS, indicating that interpretation of non-contrast-enhanced MDCT before AVS can reduce the failure rate of RAV cannulation.

Can expiratory or inspiratory contrast-enhanced computed tomography be more efficient for fast-track cannulation of the right adrenal vein in adrenal venous sampling?

PURPOSE

This study compares the usefulness of expiratory arterial phase (EAP)-contrast-enhanced computed tomography (CT) (CECT) with that of inspiratory arterial phase (IAP)-CECT in adrenal venous sampling (AVS).

METHODS

Sixty-four patients who underwent AVS and CECT at the authors' hospital between April 2013 and June 2019 were included in this study. The patients were classified into the following two groups: EAP (32 patients) and IAP (32 patients) groups. The single arterial phase images were obtained at 40 seconds in the IAP group. The double arterial phase images were obtained at 40 seconds in the early arterial phase and 55 seconds in the late arterial phase in the EAP group. The authors then compared the right adrenal vein (RAV) visualization rate on the CECT, the difference between the CECT images and adrenal venograms in the localization of the RAV orifice, the cannulation time to the RAV, and the volume of contrast agent administered intraoperatively between the two groups.

RESULTS

The rates of the RAV visualization in the EAP group were 84.4% in the early arterial phase, 93.8% in the late arterial phase, and 100% in the combined early and late arterial phases. The rate of the RAV visualization in the IAP group was 96.9%. There was no significant difference between the two groups in terms of the rate of the RAV visualization. However, there was a small difference in the location of the RAV orifice between the CECT images and adrenal venograms in the EAP group as compared with the IAP group (P < 0.001). The median time to the RAV catheterization was significantly shorter in the EAP group (27.5 minutes) than in the IAP group (35.5 minutes; P = 0.035). The rates of the RAV visualization in the EAP group were not significant between the early arterial phase, late arterial phase, and combined early and late arterial phases (P = 0.066). However, the mean volume CT dose index in the combined early and late arterial phases was significantly higher than in the early and late arterial phases (P < 0.001).

CONCLUSION

The EAP-CECT is more useful for increasing the speed of the RAV cannulation due to the small difference in the localization of the RAV orifice compared to IAP-CECT. However, since EAP-CECT has double contrast arterial phases and increased radiation exposure compared to IAP-CECT, only the late arterial phase may be acceptable to reduce radiation exposure.

Improving the Visualization of the Adrenal Veins Using Virtual Monoenergetic Images from Dual-Energy Computed Tomography before Adrenal Venous Sampling

(1) Background: This study explored the optimal energy level in advanced virtual monoenergetic images (VMI+) from dual-energy computed tomography angiography (DE-CTA) for adrenal veins visualization before adrenal venous sampling (AVS). (2) Methods: Thirty-nine patients were included in this prospective single-center study. The CT value, noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured in both adrenal veins and abdominal solid organs and were then compared between VMI+ within the range of 40-80 kiloelectron volt (keV). The visualization rate of the adrenal veins and the overall image quality of solid organs were subjectively compared among different keV VMI+. The AVS success rate was recorded for 20 patients. (3) Results: For the adrenal veins, 40 keV VMI+ had the peak CT value, noise and CNR (p < 0.05). Subjectively, the visualization rate was the highest at 40 keV (100% for the right adrenal vein, and 97.4% for the left adrenal vein) (p < 0.05). For solid organs, the CT value, noise and CNR at 50 keV were lower than those at 40 keV (p < 0.05), but the SNR was similar between 40 keV and 50 keV. The overall subjective image quality of solid organs at 50 keV was the best (p < 0.05). The AVS success rate was 95%. (4) Conclusions: For VMI+, 40 keV was the preferential energy level to obtain a high visualization rate of the adrenal veins and a high success rate of AVS, while 50 keV was the favorable energy level for the depiction of abdominal organs.