**6.1 Computed tomography**

The computed tomography is a very important exam in assessing adrenal tumors. At the phase with no contrast, a density calculus is used by means of the Hounsfield units (UH). Lesions with a <10 UH density have a high probability of being benign, whereas most adrenal adenocarcinomas present a >30 UH, which indicates low lipid content. Thus, tumors with density >10 UH demand further assessment.

Precision of diagnosis may be enhanced by the use of late stages of computed tomography with contrast and the "washout" calculation, which represents the fraction of contrast that is eliminated 10 min after administration. The finding of an average absolute "washout" of 50% after 10 min of contrast used in studies evidenced a 100% sensitivity and specificity for detection of adenomas in relation to adenocarcinomas, pheochromocytoma, and extra-adrenal metastases [17, 18].

All patients likely to be suffering from an adrenal adenocarcinoma should undergo a computed tomography of the thorax prior to surgery as any findings related to metastasis may alter the approach of treatment.

**51**

**Figure 4.**

*Preoperative Assessment of Functioning Benign Adrenocortical Tumors: A Clinical Surgical…*

Despite the fact that the computed tomography is the most important exam in assessing adrenal nodules, in some situations it is imperative to resort to a magnetic

Analysis of conventional images weighted at T1 and T2 is the most frequently used technique. Adrenal adenocarcinomas present an isointense sign in relation to the T1 liver and enhanced intensity of sign at weighted sequences at T2 (**Figure 4**). Typically, they present as large lesions (>5.0 cm) at the moment of the diagnosis

After administration of gadolinium, a slight increase of sign is noticed, as well as a swift washout of contrast, whereas malign lesions present a fast and striking

A magnetic resonance imaging may be superior to a computed tomography in the assessment of the vascular invasion, especially in terms of the inferior vena cava

In patients whose characterization of lesion malignancy could not be carried out by a tomography or resonance, additional information could be obtained through fluorine-18 fluorodeoxyglucose positron emission tomography. Malignant lesions

Metomidate binds itself specifically to Cyp11b cortical adrenal enzymes. It is used as a radiotracer at C-MTO PET, as it is capable of differentiating lesions originated at the adrenal cortical from the metastatic ones toward the adrenal [27].

*Adrenal cortical carcinoma. Magnetic resonance imaging coronal T2-weighted FSE (A) and contrast-enhanced axial T1-weighted GRE (B) sequences demonstrate a large expansive lesion involving the right adrenal gland. The lesion shows heterogeneous pattern of impregnation by the contrast agent and areas of necrosis* 

Chemical shift imaging is a detection technique for the presence of lipids. Benign lesions show as relatively shiny at the in-phase images, and they present a dimmed sign at the out-of-phase ones. The majority of adenomas are slightly hypointense or isointense to the liver on T1-weighted images and slightly hyperintense or isointense on T2-weighted images. The utilization of chemical shift techniques (in-phase or out-of-phase GRE) allows the characterization of adenomas containing microscopic fat and water protons in a same voxel (**Figure 5**). On out-ofphase images, the protons signal is null and results in signal loss as compared with

and may include necrosis, bleeding, and, frequently, calcification [19].

increase of sign followed by a rather slow washout pattern [20].

*DOI: http://dx.doi.org/10.5772/intechopen.83514*

**6.2 Magnetic resonance imaging**

resonance imaging.

in-phase images [21–24].

**6.3 Other resources of diagnosis per image**

present a high collection rate of the radiotracer.

*(hypersignal on T2-weighted sequences) (arrows).*

[25, 26].

*Preoperative Assessment of Functioning Benign Adrenocortical Tumors: A Clinical Surgical… DOI: http://dx.doi.org/10.5772/intechopen.83514*
