The effect of patient positioning on adrenal gland linear measurements estimated from computed tomographic images in healthy beagle dogs

https://doi.org/10.1016/j.domaniend.2019.106406Get rights and content

Highlights

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    Positioning in CT acquisition affects the measurements of the adrenal glands.

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    The measurements using ventral position scored as the best repeatable measurements.

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    Right lateral recumbency scored the best reducible positioning for adrenals’ measurements.

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    The position of the adrenal glands changes in different position.

Abstract

Considering that recumbency can lead to a change in localization, detectability of distinct margins and thus measurement of the organs and reconstruction quality, it is of value to evaluate the effect of positioning on the objective evaluation of abdominal organs in computed tomography (CT). The objective of the present study was to evaluate the effect of patient decubitus on adrenal gland CT biometry. For this purpose, 6 clinically healthy adult beagle dogs underwent CT examination in 4 recumbencies. The various adrenal gland's size measurements were performed by 2 observers. Statistical analyses revealed that repeatability and reproducibility was the highest on the ventral and right lateral recumbencies, respectively. Significant differences were found in the left adrenal gland's length between the different positions (P < 0.001) and the left adrenal gland's width of the cranial pole measured in the dorsal plane (P < 0.04). The measurements on the parasagittal images differed significantly for the left adrenal length (P = 0.01), cranial pole height (P = 0.03), the right adrenal gland's lateral limb's length (P = 0.05) and medial limb's caudal poles height (P < 0.01). The caudal pole height of the right adrenal gland's medial limb was significantly different (P < 0.01) in all positions on the transverse images. In addition, the adrenal position differed significantly, except for the left adrenal gland relative to the nearest renal vessel (P = 0.1). According to these results, it is recommended to perform a CT of adrenal glands always in the same recumbency. If adrenal glands are evaluated on images taken in various recumbencies, we suggest relying on the measurements made on transverse plane images.

Introduction

The adrenal glands play an important role in the endocrine system by secreting catecholamines, mineralocorticoids, and glucocorticoids [1]. Hypoadrenocorticism and hyperadrenocorticism are clinical manifestations that might originate from adrenal abnormalities and can be associated with morphological changes in those adrenal glands [2]. As diagnostic imaging is often used to evaluate abnormalities of the adrenal glands and to monitor treatment progress, practical and reliable guidelines to evaluate adrenal gland size should be developed [3].

Ultrasonography is a practical, noninvasive method for adrenal gland evaluation [3,4] that is readily available. Computed tomography (CT) has however recently gained popularity for normal and abnormal canine adrenal gland evaluation [5,6], and this has also resulted in an increased reporting of CT in veterinary diagnostic imaging literature [5,7]. The CT appearance, volume, and attenuation of normal canine adrenal glands, as well as morphologic changes in dogs with endocrinopathies have been described [8,9]. To allow an accurate assessment of adrenal glands, producing high-quality CT images is critical. Because of the narrow margins between normal adrenal measurements and adrenal size in patients with pituitary-dependent hyperadrenocorticism due to macroadenoma or microadenoma [8], assessing the effect of image-acquisition factors on the measurements might potentially improve diagnosis.

This requires an in-depth evaluation of factors such as positioning that might influence an objective evaluation.

Except for studies of the urogenital tract, the positioning for abdominal CT examination is frequently based on the preference of the examiner. However, ventral decubitus is often suggested for adrenal scanning [9]. Different recumbencies can lead to changes in localization, the detection of organ margins, and reconstruction quality [10]. To perform adrenal measurements with the highest repeatability (ie, the variability between consecutive measurements made by the same observer) and reproducibility (ie, the variability between measurements made by different observers), it is important to evaluate the influence of recumbency and to identify the optimal positioning.

The aims of this study were the following:

  • a.

    Evaluate the overall effect of patient decubitus on the adrenal gland size measurements on CT.

  • b.

    Assess the repeatability and reproducibility of adrenal gland measurements in various recumbencies.

  • c.

    Determine the displacement of the adrenal glands from adjacent landmarks in various positions.

Section snippets

Material and methods

Six adult, neutered experimental beagle dogs (4 males and 2 females) with a median weight of 12.25 kg (range 11–13.7 kg) and a median age of 53 mo (range 30–54 mo) were used in this study. Based on physical examination, clinical history, and blood work, all dogs were determined to be healthy. The Faculty of Veterinary Medicine ethical committee (Ghent University; EC 2014–181) approved the study.

Results

The results of the analyses of size differences in the different recumbencies for the various measurements are presented in Table 1. A significant size difference between the different recumbencies was found for LAL1, LACrW1, LAL2, LACrH2, RALL2, RACdMH2, and RACdMH3.

For the repeatability, the ventral position scored best for 9 of the measurements, the dorsal and right lateral positions for 5, and the left lateral position for 4 measurements, respectively (Fig. 3). A significant bias was found

Discussion

This study was conducted to evaluate the effect of positioning on adrenal gland CT measurements. Overall, 3 objectives were assessed. The adrenal displacement from adjacent landmarks between various positions was evaluated, and the repeatability and reproducibility of adrenal measurements in various recumbencies were determined. In addition, assessment of size differences in different positions was conducted.

Other researchers assessed the effects of positioning on size, detectability,

Conclusion

Based on our results, no specific recumbency outperforms the other ones in terms of repeatability and reproducibility. However, due to the adrenal glands size differences in different positions, it is important to adhere to a standard recumbency for CT. The position of the adrenal gland changes significantly except when the distance between the left adrenal gland and the nearest renal vessel is used. As that distance was consistent in the different recumbencies, it should be used in surgical

Acknowledgments

The study has been performed in department of Veterinary Medical Imaging and Small Animal Orthopedics, Ghent University, Belgium. The authors disclose no conflict of interest.

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