Adrenal Nodule MRI Calculator

Helps distinguish between adenomas and malignant tumors based on quantitative signal measurements.

Refer to the text below the tool for more information about the ratio formulas and their adenoma suggested cut-off values.


Chemical shift magnetic resonance (MR) imaging can be used to distinguish between adenomas and malignant tumors, by depicting the intracytoplasmic fat in adenomas.

This adrenal nodule MRI calculator brings together several quantitative signal drop calculation methods and their suggested cut-off values for adenomas. Most studies use the liver, spleen, or paraspinal muscles as a reference.


  • Adrenal signal intensity index (ASII) = (Adrenal nodule SI in-phase - Adrenal nodule SI out-of-phase) /Adrenal nodule SI in-phase X 100
  • Adrenal-to-spleen CSI ratio = (Adrenal nodule SI out-phase / Spleen SI out-of-phase) / (Adrenal nodule SI in-phase / Spleen SI in-phase)
  • Adrenal-to-spleen ratio (ASR) = (((Adrenal nodule SI out-phase / Spleen SI out-of-phase) / (Adrenal nodule SI in-phase / Spleen SI in-phase)) – 1) x 100
  • Adrenal-to-liver ratio (ALR) = (((Adrenal nodule SI out-phase / Liver out-of-phase) / (Adrenal nodule SI in-phase / Liver in-phase)) – 1) x 100
  • Adrenal-to-muscle ratio (AMR) = (((Adrenal nodule SI out-phase / Muscle out-of-phase) / (Adrenal nodule SI in-phase / Muscle in-phase)) – 1) x 100

Adrenal nodule SI in-phase
Adrenal nodule SI out-of-phase
Spleen SI in-phase
Spleen SI out-of-phase

Optional

Note: The following fields are optional, however if you need to calculate Adrenal-to-liver (ALR) and/or Adrenal-to-muscle ratio (AMR) as well, please provide some values for them too.
Liver in-phase
Liver out-of-phase
Muscle in-phase
Muscle out-of-phase
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Steps on how to print your input & results:

1. Fill in the calculator/tool with your values and/or your answer choices and press Calculate.

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.


 

Adrenal Nodule MRI Ratios Explained

Chemical shift magnetic resonance (MR) imaging can be used to distinguish between adenomas and malignant tumors, by depicting the intracytoplasmic fat in adenomas.

This adrenal nodule MRI calculator brings together several quantitative signal drop calculation methods and their suggested cut-off values for adenomas.

The formulas used are summarized below:

One of the simplest quantitative signal methods is to determine the percentage of signal drop relative to the lesion’s signal intensity on the in-phase images. This is referred to as the ASII.

  • Adrenal signal intensity index (ASII) = (Adrenal nodule SI in-phase - Adrenal nodule SI out-of-phase) /Adrenal nodule SI in-phase X 100
  • Adrenal-to-spleen CSI ratio = (Adrenal nodule SI out-phase / Spleen SI out-of-phase) / (Adrenal nodule SI in-phase / Spleen SI in-phase)
  • Adrenal-to-spleen ratio (ASR) = (((Adrenal nodule SI out-phase / Spleen SI out-of-phase) / (Adrenal nodule SI in-phase / Spleen SI in-phase)) – 1) x 100
  • Adrenal-to-liver ratio (ALR) = (((Adrenal nodule SI out-phase / Liver out-of-phase) / (Adrenal nodule SI in-phase / Liver in-phase)) – 1) x 100
  • Adrenal-to-muscle ratio (AMR) = (((Adrenal nodule SI out-phase / Muscle out-of-phase) / (Adrenal nodule SI in-phase / Muscle in-phase)) – 1) x 100

Please note that spleen imaging is most commonly used as reference tissue because liver or muscle measurements may become unreliable due to fatty infiltration. However, the former may become an option if the spleen may have iron deposits.

Lipid rich-adenoma is likely if either is present:

  • Adrenal signal intensity index (ASII) >16.5% at 1.5 Tesla (or >1.7% at 3 Tesla);
  • Adrenal-to-spleen CSI ratio of less than 0.71;*
  • Adrenal-to-spleen (ASR) ≤ -35.9% at 1.5 Tesla (or ≤ 17.2% at 3 Tesla);
  • Adrenal-to-liver (ALR) ≤ -32.6% at 1.5 Tesla (or ≤ 24.5% at 3 Tesla);
  • Adrenal-to-muscle ratio (AMR) ≤ -29.3% at 1.5 Tesla (or ≤ 39.6 % at 3 Tesla);

* CSI ratio >=0.71 is indeterminate. Consider CT washout test.

 

References

Adam, Sharon Z., et al. “Chemical shift MR imaging of the adrenal gland: principles, pitfalls, and applications.” Radiographics. 2016; 36.2. 414-432.

Schieda, Nicola, and Evan S. Siegelman. “Update on CT and MRI of Adrenal Nodules.” American Journal of Roentgenology. 2017; 208.6. 1206-1217.

Blake MA, Cronin CG, Boland GW. Adrenal imaging. AJR Am J Roentgenol. 2010; 194 (6): 1450-60.

Caoili EM, Korobkin M, Francis IR, et al. Adrenal masses: characterization with combined unenhanced and delayed enhanced CT. Radiology 2002; 222:629-633.


Specialty: Oncology

Article By: Denise Nedea

Published On: July 13, 2020

Last Checked: July 13, 2020

Next Review: July 13, 2025