# Radiology calculators for the report

> Adrenal washout, ellipsoid volume, PSA density and volume doubling time: the calculation, the threshold with its source and the line ready for the report.

_Category: Calculators · publicado em 2026-11-10_

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## Page summary

- **What this page explains:** Adrenal washout, ellipsoid volume, PSA density and volume doubling time: the calculation, the threshold with its source and the line ready for the report.
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## Classifications with a calculator

-   [ACR TI-RADS](https://www.laudos.ai/classificacoes/tirads "ACR TI-RADS")
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## Questions and answers

### How is absolute adrenal washout calculated?

Absolute washout = 100 × (portal venous phase attenuation − delayed phase attenuation) ÷ (portal venous phase attenuation − unenhanced attenuation), with the three attenuation values in HU and the delayed phase at 15 minutes.

### What is the ellipsoid volume formula?

Volume = axis 1 × axis 2 × axis 3 × π/6. The three axes are orthogonal to each other and in the same unit.

### How is PSA density calculated?

Divide the serum PSA, in ng/mL, by the prostate volume, in cm³. A PSA of 6.2 ng/mL with a prostate of 47.2 cm³ gives a density of 0.13 ng/mL/cm³.

### How is volume doubling time calculated?

VDT = interval between the exams, in days, × ln 2 ÷ ln(V2 ÷ V1), where V1 is the prior volume and V2 the current one. A nodule that went from 120 to 180 mm³ in 90 days has a VDT of 154 days.

## Source

[Adrenal washout](https://www.laudos.ai/en/calculadoras/washout-adrenal "Adrenal washout")

Mayo-Smith WW et al. Management of Incidental Adrenal Masses: A White Paper of the ACR Incidental Findings Committee. JACR 2017;14(8):1038-1044. [DOI 10.1016/j.jacr.2017.05.001](https://doi.org/10.1016/j.jacr.2017.05.001 "Scientific article (DOI)")

[PSA density](https://www.laudos.ai/en/calculadoras/densidade-de-psa "PSA density")

Turkbey B et al. Prostate Imaging Reporting and Data System Version 2.1. Eur Urol 2019. [DOI 10.1016/j.eururo.2019.02.033](https://doi.org/10.1016/j.eururo.2019.02.033 "Scientific article (DOI)")

[Volume doubling time](https://www.laudos.ai/en/calculadoras/tempo-de-duplicacao-de-volume "Volume doubling time")

VDT = interval x ln 2 / ln(V2/V1) (Schwartz, 1961). Reference ranges: NELSON (VDT < 400 days positive; 400 to 600, indeterminate) and BTS 2015 (discharge only with VDT > 600 days by volumetry).

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