Volume Calculator

About Organ Volume Calculation in Radiology

Accurate organ volume measurement is essential in diagnostic radiology for assessing organ enlargement, monitoring disease progression, and surgical planning. The prolate ellipsoid formula is the standard method for estimating organ volumes from imaging measurements.

The Ellipsoid Formula

This formula assumes the organ approximates an ellipsoid shape. The multiplier (π/6 ≈ 0.523) derives from the mathematical volume of an ellipsoid: V = (4/3) × π × (a/2) × (b/2) × (c/2), which simplifies to V = π/6 × L × W × H.

Organ-Specific Multipliers

• 0.523 (π/6) - Prostate, Ovarian, Thyroid, Renal, Generic ellipsoid
• 0.625 - Bladder (accounts for more spherical shape when distended)
• 0.71 - Testicular (Lambert formula, validated for testicular morphology)

Clinical Applications by Organ

Prostate Volume

Prostate volume measurement is critical for benign prostatic hyperplasia (BPH) assessment, brachytherapy planning, and calculating PSA density. Normal prostate volume is 20-30 cc in younger men, increasing with age. Volumes >30 cc suggest enlargement.

PSA Density (PSAD)

PSA Density = Serum PSA ÷ Prostate Volume. PSAD adjusts PSA for gland size, improving cancer detection specificity. PSAD >0.15 ng/mL/cc is associated with increased risk of clinically significant prostate cancer and is used in PI-RADS assessment.

Ovarian Volume

Ovarian volume varies with menstrual cycle and age. Normal premenopausal volume is 3-10 cc per ovary. Volume >10 cc is one of the Rotterdam criteria for polycystic ovary syndrome (PCOS). Postmenopausal ovaries typically measure less than 5 cc.

Thyroid Volume

Each thyroid lobe normally measures 7-10 mL, with total thyroid volume of 10-20 mL. Thyroid volume assessment is important for goiter evaluation, Graves' disease monitoring, and radioiodine therapy dosimetry.

Renal Volume

Normal kidney volume is 110-190 mL in males and 90-150 mL in females, decreasing approximately 10% per decade after age 50. Renal volume correlates with nephron mass and is used in chronic kidney disease assessment.

Bladder Volume

Normal bladder capacity is 400-600 mL. Post-void residual (PVR) measurement is clinically important: PVR less than 50 mL is normal, while >100 mL suggests incomplete emptying requiring evaluation.

Testicular Volume

Normal adult testicular volume is 12-30 mL per testis. Volume less than 12 mL may indicate testicular atrophy. The Lambert formula (multiplier 0.71) provides more accurate testicular volume estimation than the standard ellipsoid formula.

References

1. Turkbey B, Rosenkrantz AB, Haider MA, et al. Prostate Imaging Reporting and Data System Version 2.1: 2019 Update. Eur Urol. 2019;76(3):340-351. doi:10.1016/j.eururo.2019.02.033
2. Wasserman NF. Benign Prostatic Hyperplasia: A Review and Ultrasound Classification. Radiol Clin North Am. 2006;44(5):689-710. doi:10.1016/j.rcl.2006.07.005
3. Rotterdam ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. Revised 2003 consensus on diagnostic criteria for polycystic ovary syndrome. Hum Reprod. 2004;19(1):41-47.
4. Hegedüs L. Thyroid ultrasound. Endocrinol Metab Clin North Am. 2001;30(2):339-360. doi:10.1016/s0889-8529(05)70190-0
5. Cheong B, Muthupillai R, Rubin MF, Flamm SD. Normal values for renal length and volume as measured by magnetic resonance imaging. Clin J Am Soc Nephrol. 2007;2(1):38-45. doi:10.2215/CJN.00930306
6. Dicuio M, Pomara G, Menchini Fabris F, et al. Measurements of urinary bladder volume: comparison of five ultrasound calculation methods. Arch Ital Urol Androl. 2005;77(1):60-62.
7. Lambert B. The frequency of mumps and of mumps orchitis and the consequences for sexuality and fertility. Acta Genet Stat Med. 1951;2(Suppl 1):1-166.
8. Sakamoto H, Saito K, Oohta M, et al. Testicular volume measurement: comparison of ultrasonography, orchidometry, and water displacement. Urology. 2007;69(1):152-157. doi:10.1016/j.urology.2006.09.012