Everything you need to know about Computed Tomography (CT) & CT Scanning

Ask the Fish
  • CTisus CT Scanning
  • CTisus CT Scanning
  • CTisus CT Scanning
  • CTisus CT Scanning
  • CTisus CT Scanning
  • CTisus CT Scanning
  • CTisus CT Scanning
Adrenal: Incidental Adrenal Masses Imaging Pearls - Learning Modules | CT Scanning | CT Imaging | CT Scan Protocols - CTisus
Imaging Pearls ❯ Adrenal ❯ Incidental Adrenal Masses
    Share on Facebook  

-- OR --

  • “Adrenal cortical hyperplasia manifests radiologically as the nonmalignant growth, or enlargement of the adrenal glands, specifically the cortex, although the cortex cannot be definitively identified by conventional imaging. Controlled by the pituitary gland, the adrenal cortex drives critical processes, such as cortisol, mineralocorticoid, and sex hormone production. Any disruption in the multiple enzymes and hormones involved in these pathways may cause serious or life-threatening symptoms, often associated with anatomical changes of the adrenal glands. Diagnosis and treatment of adrenal cortical hyperplasia requires a thorough clinical evaluation. As imaging has become more robust, so has its role in the diagnosis and treatment of adrenal conditions. CT has been the primary modality for adrenal imaging due to reproducibility, temporal and spatial resolution and broad access. MRI serves a complimentary role in adrenal imaging and can be used to further evaluate indeterminate CT findings or serve as an adjunct tool without the use of ionizing radiation. Ultrasound and fluoroscopy (genitography) are most commonly used in children and fetuses to evaluate congenital adrenal hyperplasia.”


    Adrenal Cortical Hyperplasia: Diagnostic Workup, Subtypes, Imaging Features and Mimics.
Agrons M et al.
Br J Radiol. 2017 Jul 14:2017030 doi: 10.1259/bjr.20170330
  • People with CAH lack one of the enzymes (proteins that cause chemical changes in the body), steroid 21-hydroxylase. This results in low production of the hormone that helps the body respond to stress (cortisol), and in most cases of classic CAH they lack another hormone needed to retain sodium (salt). This imbalance causes over-production of sex hormones (in males androgens, and in females, estrogens).  CAH can be severe (classic) and diagnosed in the newborn, but it can also be mild (nonclassic) and not show up until later childhood, adolescence or adulthood.
  • “People with CAH lack one of the enzymes (proteins that cause chemical changes in the body), steroid 21-hydroxylase. This results in low production of the hormone that helps the body respond to stress (cortisol), and in most cases of classic CAH they lack another hormone needed to retain sodium (salt). This imbalance causes over-production of sex hormones (in males androgens, and in females, estrogens).  CAH can be severe (classic) and diagnosed in the newborn, but it can also be mild (nonclassic) and not show up until later childhood, adolescence or adulthood.”

    
Congenital adrenal hyperplasia 
Deborah P Merke, Stefan R Bornstein 
www.thelancet.com Vol365 June18,2005
  • “Based on a review of autopsy series of approximately 35,000 subjects, the prevalence of ACH is estimated to be 0.51%, increasing with age. Hyperplasia can manifest as either a diffuse process involving the entire adrenal(s) or as nodular hyperplasia. Nodular hyperplasia is usually multifocal and bilateral, also increasing in prevalence with age. In a series of 113 consecutive adult necropsies, the adrenals were examined histologically and 35% were described as normal, 50% as having mild nodularity, and the remainder as having distinct nodularity. The average age of patients with distinct nodularity was 65 years versus 50 years for the normal group. This study demonstrated that an increasingly nodular appearance of the adrenal can occur with age.”

    
From the Radiologic Pathology Archives: Adrenal Tumors and Tumor-like Conditions in the Adult: Radiologic-Pathologic Correlation
Grant E. Lattin, Jr et al.
RadioGraphics 2014 34:3, 805-829 
  • “Imaging characteristics of adrenal tumors on CT scan predict benign pathology 100% of the time. Regardless of size, when interpreted as benign on CT scan, laparoscopic adrenalectomy, if technically feasible, should be the technique used when surgery is offered, or close surveillance may be a safe alternative.”


    Computed Tomography in the Management of Adrenal Tumors: Does Size Still Matter?
Azoury SC, Nagarajan N, Young A, Mathur A, Prescott JD, Fishman EK, Zeiger MA
J Comput Assist Tomogr. 2017 Jan 20 [Epub ahead of print]
  • METHODS: A retrospective review was conducted of patients who underwent unilateral adrenalectomy for an adrenal mass between January 2005 and July 2015. Tumors were classified as benign, indeterminate, or malignant based on preoperative CT findings.


    RESULTS: Of 697 patients who underwent unilateral adrenalectomy, 216 met the inclusion criteria. Pathology was benign in 88.4%, indeterminate in 2.3%, and malignant in 9.3%, with a median tumor diameter of 2.7 cm (interquartile range, 1.7-4.1 cm) and 9.5 cm (interquartile range, 7.1-12 cm) in the benign and malignant groups, respectively (P < 0.001). Of the tumors with benign features on CT, 100% (143/143) had benign final pathology.”


    Computed Tomography in the Management of Adrenal Tumors: Does Size Still Matter?
Azoury SC, Nagarajan N, Young A, Mathur A, Prescott JD, Fishman EK, Zeiger MA
J Comput Assist Tomogr. 2017 Jan 20 [Epub ahead of print]
  • Adrenal Gland Imaging: Pitfalls
    - Pseudolesions
    - accessory spleen
    - celiac plexus
    - lymph nodes
    - gastric fundal diverticula,
    - venous varices
    - renal lesions
  • Adrenal Gland Imaging: Pitfalls
    - Pheochromocytoma is a great mimicker especially when it presents as an incidental finding
    - Collision tumors that have been defined as representing 2 pathologically distinct lesions (such as a benign and a malignant lesion), giving the appearance of a single lesion. The benign features of portions of a conglomerate lesion (ie, intralesional lipid) could lead to the false conclusion that the entire mass is benign.
  • Adrenal Gland Imaging: Pitfalls
    - Metastases to the adrenal from renal cell carcinoma or hepatoma can be confused with pheochromocytoma or even adenoma based on washout values.
    - Macroscopic fat in an adrenal mass is effectively diagnostic of adrenal myelolipoma; however, smaller amounts of fat can be present within myelolipomatous metaplasia of adrenal cortical neoplasms such as degenerated adenomas and adrenal cortical carcinomas.
  • “Although incidentally detected adrenal nodules are most commonly benign adrenal adenomas, accurate imaging char- acterization is important, as the risk of malignancy increases substantially in patients with a history of primary malignancy and in adrenal nodules measuring more than 4 cm.”


    Pitfalls in Adrenal Imaging
Taner AT et al.
Semin Roentgenol. 2015 Oct;50(4):260-72.
  • “Adrenal adenoma is the most common AI, and 70% of cases contain significant amounts of intracellular lipid. The presence of intracellular lipid (i.e., lipid-rich adenoma) allows differentiation from lipid-poor adenomas and nonadenomas with high specificity. Adrenal mass characterization with the use of CT requires placing an ROI over one-half to two-thirds of the surface area of the mass while avoiding areas of necrosis and calcification.”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations  Garrett RW et al AJR 2016; 206:1170–1178
  • “Myelolipomas contain macroscopic fat, which is characterized by attenuation of less than −20 HU on CT and signal dropout on fat-suppressed MRI sequences . Macroscopic fat rarely can be seen in adrenal adenomas, adrenocortical carcinomas (ACCs), and pheochromocytomas, and large myelolipomas may be difficult to distinguish from liposarcomas .” 

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations  Garrett RW et al AJR 2016; 206:1170–1178 
  • “The majority of AIs are benign in patients with no previously known malignancy. Even in patients with a primary nonadrenal malignancy known to be associated with a high frequency of adrenal metastases, only 50% of AIs are caused by metastatic disease.”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 
  • “Approximately 30% of adenomas, which are the most common AIs, are lipid poor and cannot be distinguished from malignancy on unenhanced CT. Routine CECT cannot distinguish adenomas from nonadenomas because of the overlap in attenuation values .”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 
  • “Although most patients with AIs have nonfunctioning adenomas (80%), 5–10% have subclinical or early Cushing syndrome, 5% have pheochromocytoma, and 1% have aldosteronoma.”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 
  • “The ACR algorithm considers biochemical (hormonal) evaluation, but the document states that routine hormonal evaluation of all incidentalomas “would be costly and is not routinely performed by many physicians” . Furthermore, biochemical evaluation should be considered only “if there are clinical signs or symptoms of adrenal hyperfunction”. This view is contrary to the preponderance of clinical recommendations in the endocrine literature.”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 
  • “Because pheochromocytomas have nonspecific features on imaging, and because clinical expertise in diagnosing pheochromo- cytomas may vary, it has been suggested that all adrenal masses be screened for catechol- amine excess . Plasma metanephrines have similar sensitivity and specificity for pheochromocytoma as urine fractionated metanephrines and may be considered as the first screening test.”

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations  Garrett RW et al AJR 2016; 206:1170–1178 
  • “AIs may develop cortisol hyperfunction over time, even if they are not hormonally active at the time of the initial evaluation. The risk of a mass larger than 2.4 cm becoming hormonally active is 17% at 1 year, 29% at 2 years, and 47% at 5 years. There is good agreement among the clinical recommendations that individuals with benign non- functioning AIs measuring greater than 2.4 cm should obtain annual hormonal testing for Cushing syndrome for 4 years. Other than consideration of initial biochemical evaluation of patients with signs or symptoms of adrenal hyperfunction, the ACR guidelines do not recommend long-term follow-up of hormonal function.” 

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations  Garrett RW et al AJR 2016; 206:1170–1178 
  • “Therefore, all incidentally detected adrenal masses 1 cm or larger should undergo biochemical evaluation, unless the imaging features are diagnostic of a nonfunctional process (e.g., myelolipoma or cyst). In addition to the initial biochemical evaluation, an additional yearly follow-up examination to evaluate cortisol secretion should be performed for masses larger than 2.4 cm or if such an examination is clinically indicated on the basis of new signs or symptoms.” 

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations Garrett RW et al AJR 2016; 206:1170–1178 
  • “Radiologists play a key role in characterizing adrenal masses as benign or malignant and in recommending further imaging and biochemical evaluation for AIs. Until greater agreement is reached in the medical community, it would be prudent for diagnostic radiologists to dis- cuss these topics with their endocrinology colleagues to develop a local consensus.” 

    Adrenal Incidentalomas: Clinical Controversies and Modified Recommendations  Garrett RW et al AJR 2016; 206:1170–1178 
  • “Adrenal incidentalomas (AIs) are found in approximately 4% of patients undergoing abdominal imaging, with peak prevalence in the sixth and seventh decades of life. Detection of AI warrants clinical, biochemical, and radiological evaluation to establish its secretory status and risk of malignancy. Careful review of the lipid content, size, and imaging phenotype of an adrenal mass is needed to evaluate the risk for malignancy. Identification of an AI may be an opportunity to identify an underlying secretory tumor that may have been otherwise unrecognized. A practical approach to investigation and follow-up of AIs is presented in this article.”


    Adrenal Incidentalomas: A Disease of Modern Technology Offering Opportunities for Improved Patient Care.
Ioachimescu AG et al.
Endocrinol Metab Clin North Am. 2015 Jun;44(2):335-354.
  • “The problem at hand is that approximately 85% of adrenal incidentalomas are nonfunctional and asymptomatic. Most are benign adenomas. The roughly 70% that are lipid-rich are easily characterized. However, the 30% that are lipid-poor are difficult to distinguish from ACC. Epidemiologic statistics overwhelmingly indicate that most of these lipid-poor adrenal incidentalomas are also benign.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “Current guidelines issued by the National Institutes of Health (NIH) regarding nonfunctioning incidentalomas suggest resection of lesions larger than or equal to 4 cm. Based on these guidelines and the prevalence of ACC, most laparoscopic adrenalectomies performed for biochemically silent lesions show benign adrenal adenomas. The National Italian Study Group on Adrenal Tumors found that a 4 cm adrenal lesion had a 93% sensitivity but only 24% specificity for ACC.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms 
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “There are two ways to calculate contrast washout. The first is called absolute percentage washout (APW) and the second is called relative percentage washout (RPW). APW requires a noncontrast HU measurement. APW is calculated using the formula ([enhanced HU−delayed HU]÷[enhanced HU−noncontrast HU]) × 100. Frequently, only contrast and delayed images are performed so an APW cannot be calculated. In these cases, the RPW must be used and is calculated as ([enhanced HU−delayed HU]÷enhanced HU) × 100. Because the APW includes the noncontrast measurement, it is considered more accurate.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “The most recent and possibly fastest growing segment of adrenal imaging is PET-CT scanning (Fig. 6). Using PET with fludeoxyglucose F 18 (18F FDG-PET), studies have shown very high accuracy for detecting adrenal malignancies, with sensitivity as high as 100% and specificity between 87% and 97%. The FDG uptake does not significantly differ for lipid-rich versus lipid-poor adenomas, and the sensitivity and specificity for lipid-poor adenomas are 98.5% and 92%, respectively Only 5% of normal adrenals are seen on PET alone, whereas 68% are seen on PET-CT.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms 
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “The rate of false-positive PET scan for nonfunctioning adrenal incidentalomas is 5% due to inflammatory lesions, such as sarcoid and tuberculosis, or adrenocortical hyperplasia. False-negative PET is rare but can occur if there has been extensive hemorrhage or necrosis, or if the adrenal lesion is a metastasis from a primary that is not FDG-avid.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “On noncontrast CT, a feature often associated with ACCs includes central necrosis, which can occur as the tumor outstrips its blood supply. Radiographically, this will produce heterogeneity of the attenuation coefficient. Approximately 30% of ACCs contain calcifications. It is rare to see macroscopic fat.53 On contrast-enhanced CT, there is expected imaging heterogeneity . Usually, the absolute and relative washout is less than it is for benign adenomas; however, there are rare case reports of ACCs with benign washout characteristics.”

    Radiographic Evaluation of Nonfunctioning Adrenal Neoplasms
    Mazzaglia PJ
    Surg Clin N Am 94 (2014) 625–642 
  • “ Adrenal incidentalomas are commonly noted on abdominal cross-sectional imaging studies. Most of these lesions are benign, non-functional adrenal adenomas. Certain adrenal lesions have such characteristic radiologic findings that their diagnosis can be made with virtual certainty.”
    Radiology of the Adrenal
    Udelsman R, Fishman EK
    Endorinol Metab Clin North Am 2000 Mar 29(1);27-42
  • “ At routine contrast-enhanced MDCT, adrenal masses with irregular margins or a thick enhancing rim are likely to be malignant. Smooth margins and homogeneous density can be seen in both benign and malignant adrenal masses and are insufficient for characterization.”
    Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
    Song JH et al.
    AJR 2013; 201:1248-1253
  • “ For individual morphologic features in diagnosing malignancy, irregular margins had 30-33% sensitivity and 95-96% specificity and an enhancing rim had 5-13% sensitivity and 98-99% specificity.”
    Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
    Song JH et al.
    AJR 2013; 201:1248-1253
  • “ Notably, no malignant lesions occurred in patients without a known history of cancer.”
    Morphologic Features of 211 Adrenal Masses at Initial Contrast-Enhanced CT: Can We Differentiate Benign From Malignant Lesions Using Imaging Features Alone-
    Song JH et al.
    AJR 2013; 201:1248-1253
  • Incidental Adrenal Nodule
    1. 3-7% of all CT exams
    2. Noncancer patients
    - adenoma (80%)
    - myelolipoma (6%)
    - pheochromocytoma (3%)
  • Adrenal Hyperplasia
    - Normal adrenal limbs should be ? 5 mm
    - Can cause Cushing’s syndrome or Conn syndrome
  • Adrenal Insufficiency
    - Bilateral hemorrhage à adrenal insufficiency
    - Nonspecific symptoms
    - Fatigue, weakness, muscle/joint pain
    - Abdominal pain, vomiting, diarrhea
    - Depression, behavioral changes
    - Hypotension
  • Adrenal Pseudocyst
    - Sequela of previous hemorrhage
    - Unilocular or multilocular
    - Calcification in 43%
    - Pseudocyst can be present with an adrenal tumor
  • “ The prevalence of incidental adrenal masses in abdominal CT is approximately 4%, ranging from 0.2% in patients 20-29 years old to 7% in patients over 70 years old.”
    Prevalence of adrenal incidentaloma in a contemporary computerized tomography series.”
    J Endocrinol Invest
    2006; 29:298-302
  • Adrenal Pseudocyst
    -Sequela of previous hemorrhage
    -Unilocular or multilocular
    -Calcification in 43%
    -Pseudocyst can be present with an adrenal tumor

     

  • "The goal of imaging when an incidental adrenal mass is discovered is to differentiate a benign "leave alone" mass (eg.nonhyperfunctioning tumor,myelolipoma,hemorrhage,cyst) from a mass that warrants treatment (eg, metastases, pheochromocytoma,adrenal cortical carcinoma)."

    Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
    Berland LL et al.
    J Am Coll Radiol 2010;7;754-773

  • "This white paper which represents the collective experience of the Incidental Findings Committee, using a less formal process of repeated reviews and revisions of the draft document, does not represent official ACR policy. For these reasons, this white paper should not be used to establish the legal standard of care in any particular situation."

    Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
    Berland LL et al.
    J Am Coll Radiol 2010;7;754-773

     

  • "The committee has used a consensus method based on repeated reviews and revisions of this document and a collective review and interpretation of relevant literature. This white paper provides guidance devloped by this committee for addressing incidental findings in the kidneys, liver , adrenal gland and pancreas."

    Managing Incidental Findings on Abdominal CT: White Paper of the ACR Incidental Findings Committee
    Berland LL et al.
    J Am Coll Radiol 2010;7;754-773

  • "All of the incidentally detected adrenal masses with a CT attenuation of >10 HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental mass appears to have a limited role in this patient cohort."

    The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
  • "In conclusion, the results of our study show that none of the incidentally detected adrenal masses was malignant in patients with no known cancer. If an incidental adrenal mass appears benign on imaging and the patient has no known malignancy, follow-up imaging appears to have a limited role."

    The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
  • "All of the incidentally detected adrenal masses with a CT attenuation of >10 HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental mass appears to have a limited role in this patient cohort."

    The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
  • "In conclusion, the results of our study show that none of the incidentally detected adrenal masses was malignant in patients with no known cancer. If an incidental adrenal mass appears benign on imaging and the patient has no known malignancy, follow-up imaging appears to have a limited role."

    The Incidental Indeterminate Adrenal Mass on CT (>10H) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
  • "All of the incidentally detected adrenal masses with a CT attenuation of >10HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental adrenal mass appears to have a limited role in this patient cohort." The Incidental Indeterminate Adrenal Mass on CT (> 10HU) in Patients Without Cancer: Is Further Imaging Necessary? Follow-Up of 321 Consecutive Indeterminate Adrenal Masses Song JH et al. AJR 2007; 189:1119-1123
  • Objective: The objective of our study was to determine whether follow-up imaging evaluation is necessary for incidentally discovered indeterminate adrenal lesions (>10HU) on CT in patients with no known malignancy. Conclusion:All of the incidentally detected adrenal masses with a CT attenuation of >10HU were benign in patients with no known malignancy. Follow-up imaging to characterize an incidental adrenal mass appears to have a limited role in this patient cohort.
  • "There are only slight differences in attenuation of adrenal nodules measured on scans obtained with different scanners." Adrenal Lesions: Attenuation measurement Differences between CT Scanners Hahn PF et al. Radiology 2006; 240:458-463.
  • Absolute Contrast Enhancement Washout
    -[(E-D/E-U)] x 100
    - Where E is the enhanced attenuation value, D is the delayed enhancement value, and U is the unenhanced value
© 1999-2017 Elliot K. Fishman, MD, FACR. All rights reserved.