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

Abstract

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.

Qualitative Heterogeneous Signal Drop on Chemical Shift (CS) MR Imaging: Correlative Quantitative Analysis between CS Signal Intensity Index and Contrast Washout Parameters Using T1-Weighted Sequences

“…Conversely, in AL with no signal drop on CS, the values of wash-out parameters, both of RWO and AWO, were significantly lower, with percentage values of both RWO and AWO suggestive of non-adenomas adrenal tumors, even with the occurrence (33%) of "lipid-poor" adenomas in this group of lesions. Our results are in line with the data reported in the literature regarding the percentage values of RWO and AWO observed in different AL such as adenomas, benign, non-adenomas, and malignant adrenal tumors [13,[23][24][25][26][27]. Indeed, a previous study [13] reported that "lipidpoor" adenomas may show RWO and AWO values, both at 5 and 10 min after contrast administration, significantly lower compared to "lipid-rich" adenomas, but similar to those of non-adenoma lesions such as pheochromocytoma or malignant tumors.…”

“…These data are concordant with the results of other studies which suggested that lesion wash-out may be assessed earlier at 5 min post-contrast injection, shortening the dynamic imaging protocols both on MRI [7] and computed tomography (CT) [17][18][19]. In this regard, a modified MRI protocol using different imaging parameters has been recently proposed for the characterization of adrenal nodules [26]. On a final note, it should be highlighted that DCE quantitative parameters values showed greater ranges than ASII in our study; while we cannot provide a clear explanation to this finding, it might suggest a higher degree of variability, making ASII preferable over RWO and AWO.…”

Acute spontaneous unilateral adrenal hemorrhage: etiology and imaging findings in six cases

“…However, the adrenal gland is also commonly the site of metastases and hemorrhages, as well as, to a lesser degree, primary tumors ( 16 ) . Differentiating between potentially malignant and benign lesions is essential, because metastases to the adrenal glands are common ( 17 ) , so much so that several studies are being developed in order to examine the issue ( 18 - 21 ) . Although adrenal hemorrhage is rare, its consequences are potentially fatal, especially if it is not diagnosed in a timely manner.…”

Diffusion-weighted imaging and apparent diffusion coefficient values for evaluating terminal ileitis in patients with Crohn’s disease

“…Recent studies have highlighted the importance of MRI in the improvement of the diagnosis of abdominal and gastrointestinal diseases (13)(14)(15)(16)(17) . Patients with active inflammation identified by colonoscopy had more significant restricted diffusion, more pronounced edema, and greater wall thickening than did those with inactive disease.…”