Incidentaloma MRI
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American Roentgen Ray Society Images of Incidentaloma MRI |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mohammed Abdelwahed M.D[2]
Overview
Adrenal MRI may be helpful in the diagnosis of incidentaloma. Findings on MRI suggestive of incidentaloma include mild enhancement and a rapid washout of contrast, while malignant lesions show rapid and marked enhancement and a slower washout pattern. MRI has advantages in certain clinical situations. The advantages of MRI over CT are its lack of radiation exposure, lack of iodine-based contrast media and its superior tissue contrast resolution.
MRI
- Findings on MRI suggestive of incidentaloma include:[2][3]
- T1 and T2-weighted imaging can distinguish benign adenomas from malignancy and pheochromocytoma.
- MRI has advantages in certain clinical situations. The advantages of MRI over CT are its lack of radiation exposure, lack of iodine-based contrast media and its superior tissue contrast resolution.
- On gadolinium-diethylene triamine pentaacetic acid (DTPA)-enhanced MRI, adenomas demonstrate mild enhancement and a rapid washout of contrast, while malignant lesions show rapid and marked enhancement and a slower washout pattern.
Chemical shift
- Chemical shift imaging relies on the fact that protons in water vibrate at a slightly different frequency than protons in lipid.[4][5][6]
- By selecting appropriate sequencing parameters, separate images can be generated with water and fat protons oscillating in phase or out of phase to each other.
- Benign adrenal cortical adenomas lose signal on out-of-phase images but appear relatively bright on in-phase images.
- Whereas malignant lesions, pheochromocytomas, and lipid-poor adrenal adenomas remain unchanged because all lack intracellular lipid.
References
- ↑ Sahdev A (2017). "Recommendations for the management of adrenal incidentalomas: what is pertinent for radiologists?". Br J Radiol. 90 (1072): 20160627. doi:10.1259/bjr.20160627. PMID 28181818.
- ↑ Peppercorn PD, Grossman AB, Reznek RH (1998). "Imaging of incidentally discovered adrenal masses". Clin Endocrinol (Oxf). 48 (4): 379–88. PMID 9640401.
- ↑ Sahdev A, Reznek RH (2004). "Imaging evaluation of the non-functioning indeterminate adrenal mass". Trends Endocrinol Metab. 15 (6): 271–6. doi:10.1016/j.tem.2004.06.012. PMID 15358280.
- ↑ Israel GM, Korobkin M, Wang C, Hecht EN, Krinsky GA (2004). "Comparison of unenhanced CT and chemical shift MRI in evaluating lipid-rich adrenal adenomas". AJR Am J Roentgenol. 183 (1): 215–9. doi:10.2214/ajr.183.1.1830215. PMID 15208141.
- ↑ Young WF (2011). "Conventional imaging in adrenocortical carcinoma: update and perspectives". Horm Cancer. 2 (6): 341–7. doi:10.1007/s12672-011-0089-z. PMID 21997291.
- ↑ Haider MA, Ghai S, Jhaveri K, Lockwood G (2004). "Chemical shift MR imaging of hyperattenuating (>10 HU) adrenal masses: does it still have a role?". Radiology. 231 (3): 711–6. doi:10.1148/radiol.2313030676. PMID 15118113.