Evaluation of Relative Wash-In Ratio of Adrenal Lesions at Early Biphasic CT

Foti, Giovanni; Faccioli, Niccolò; Manfredi, Riccardo; Mantovani, William; Mucelli, Roberto Pozzi

doi:10.2214/ajr.09.3636

Cited by 24 publications

(25 citation statements)

References 24 publications

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“…Our results show that the probability of a lesion with a type 1 PE being an adenoma was 90.9%. Chung et al (15) and Foti et al (20) evaluated malignant adrenal lesions and found that none exhibited the peak of enhancement in the arterial phase. However, it is recognized that hypervascular nonadenomas, including pheochromocytoma, metastases from hypervascular extra-adrenal primary malignancies such as renal cell carcinoma or hepatocellular carcinoma, and primary adrenal carcinomas, may show a type 1 PE (10,11) .…”

Section: Discussionmentioning

confidence: 99%

Modified approach to the characterization of adrenal nodules using a standard abdominal magnetic resonance imaging protocol

et al. 2017

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ObjectiveTo describe a modified approach to the evaluation of adrenal nodules using a standard abdominal magnetic resonance imaging protocol.Materials and MethodsOur sample comprised 149 subjects (collectively presenting with 132 adenomas and 40 nonadenomas). The adrenal signal intensity index was calculated. Lesions were grouped by pattern of enhancement (PE), according to the phase during which the wash-in peaked: arterial phase (type 1 PE); portal venous phase (type 2 PE); and interstitial phase (type 3 PE). The relative and absolute wash-out values were calculated. To test for mean differences between adenomas and nonadenomas, Student's t-tests were used. Receiver operating characteristic curve analysis was also performed.ResultsThe mean adrenal signal intensity index was significantly higher for the adenomas than for the nonadenomas (p < 0.0001). Chemical shift imaging showed a sensitivity and specificity of 94.4% and 100%, respectively, for differentiating adenomas from nonadenomas. Of the adenomas, 47.6%, 48.5%, and 3.9%, respectively, exhibited type 1, 2, and 3 PEs. For the mean wash-in proportions, significant differences were found among the enhancement patterns. The wash-out calculations revealed a trend toward better lesion differentiation for lesions exhibiting a type 1 PE, showing a sensitivity and specificity of 71.4% and 80.0%, respectively, when the absolute values were referenced, as well as for lesions exhibiting a type 2 PE, showing a sensitivity and specificity of 68.0% and 100%, respectively, when the relative values were referenced. The calculated probability of a lipid-poor lesion that exhibited a type 3 PE being a nonadenoma was > 99%.ConclusionSubgrouping dynamic enhancement patterns yields high diagnostic accuracy in differentiating adenomas from nonadenomas.

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Section: Discussionmentioning

confidence: 99%

Modified approach to the characterization of adrenal nodules using a standard abdominal magnetic resonance imaging protocol

et al. 2017

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“…When enhancement characteristics of an adrenal lesion are evaluated at CT, the imaging study should ideally include nonenhanced, portal venous (60-75 sec), and delayed (15 min) phases. Studies have shown that calculations that use the arterial phase are less sensitive and less specific than widely used washout calculations (33,34), and arterial phase scans are therefore not recommended as part of routine dedicated adrenal protocols. Washout is calculated at adrenal CT by using two different formulasabsolute washout and relative washout ( Table 2).…”

Section: Adrenal Adenomasmentioning

confidence: 99%

Chemical Shift MR Imaging of the Adrenal Gland: Principles, Pitfalls, and Applications

Adam¹,

Nikolaidis²,

Horowitz³

et al. 2016

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Adrenal lesions are a common imaging finding. The vast majority of adrenal lesions are adenomas, which contain intracytoplasmic (microscopic) fat. It is important to distinguish between adenomas and malignant tumors, and chemical shift magnetic resonance (MR) imaging can be used to accomplish this distinction by depicting the fat in adenomas. Chemical shift imaging is based on the difference in precession frequencies of water and fat molecules, which causes them to be in different relative phases during the acquisition sequence and allows in-phase and opposed-phase images to be obtained. It is important to acquire these images by using the earliest possible echo times, with the opposed-phase echo before the in-phase echo, and by using a single breath hold to preserve diagnostic accuracy. Intracytoplasmic fat is depicted as signal drop on opposed-phase images when compared with in-phase images. Both qualitative and quantitative methods for assessing signal drop are detailed. The appearances of adrenal adenomas and other adrenal tumors on chemical shift MR images are described, and discriminatory ability at chemical shift MR imaging compared with that at adrenal computed tomography (CT) is explained. Other adrenal-related conditions in which chemical shift MR imaging is helpful are also discussed. Chemical shift MR imaging is a robust tool for evaluating adrenal lesions that are indeterminate at nonenhanced CT. However, it is important to know the advantages and disadvantages, including several potential imaging pitfalls. The characterization of adrenal lesions by using chemical shift MR imaging and adrenal CT should always occur in the appropriate clinical setting.

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“…Benign lesions may have patent vessels that allow for easy contrast passage and exhibit fast wash-in and wash-out from the arterial to portal phases. Malignant lesions have a high cellular density and densely packed vessels, causing higher resistance to contrast flow and slow wash-in and wash-out patterns [18] . The drawback is that there is some overlap in contrast-enhancement patterns between adenomas and non-adenomas; therefore, wash-in patterns are not always reliable [19] .…”

Section: Ctmentioning

confidence: 99%

“…These non-FDG agents currently have limited clinical roles; thus, the focus in this section is on 18 F-FDG-PET examinations.…”

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confidence: 99%

Cross-sectional imaging work-up of adrenal masses

Korivi

Elsayes²

2013

WJR

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Advances in medical imaging with current cross-section modalities enable non-invasive characterization of adrenal lesions. Computed tomography (CT) provides characterization with its non-contrast and wash-out features. Magnetic resonance imaging (MRI) is helpful in further characterization using chemical shift imaging (CSI) and MR spectroscopy. For differentiating between benign and malignant masses, positron emission tomography (PET) imaging is useful with its qualitative analysis, as well as its ability to detect the presence of extra-adrenal metastases in cancer patients. The workup for an indeterminate adrenal mass includes evaluation with a non-contrast CT. If a lesion is less than 10 Hounsfield Units on a non-contrast CT, it is a benign lipid-rich adenoma and no further work-up is required. For the indeterminate adrenal masses, a lipid-poor adenoma can be differentiated from a metastasis utilizing CT wash-out features. Also, MRI is beneficial with CSI and MR spectroscopy. If a mass remains indeterminate, PET imaging may be of use, in which benign lesions demonstrate low or no fluorodeoxyglucose activity. In the few cases in which adrenal lesions remain indeterminate, surgical sampling such as percutaneous biopsy can be performed.

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Evaluation of Relative Wash-In Ratio of Adrenal Lesions at Early Biphasic CT

Abstract: Relative percentage wash-in ratio may help in differentiating adenoma from metastasis and in guiding the decision to perform CT directed at the adrenal glands when unenhanced CT is not available.

Cited by 24 publications

References 24 publications

Modified approach to the characterization of adrenal nodules using a standard abdominal magnetic resonance imaging protocol

Modified approach to the characterization of adrenal nodules using a standard abdominal magnetic resonance imaging protocol

Chemical Shift MR Imaging of the Adrenal Gland: Principles, Pitfalls, and Applications

Cross-sectional imaging work-up of adrenal masses

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