Radiology Volume Calculator
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3- dimensional volume measurements are far superior to 2- dimensional measurements as anatomical and pathological structures can have one dimension skewed. For example, a tumor can be small in the axial dimensions but oblong, giving rise to a larger volume than what would have been estimated using two dimensions. These volume measurements are also ideal for the follow-up of tumors post-treatment as these tend to have irregular shapes.
Although direct volumetric measurements are ideal, this may not be feasible in all cases as it is time-consuming. Volume calculations are a good alternative. That said, the volume may not be feasible in all conditions a single dimension can also be useful.
The generic formula for calculating volume on ultrasound / CT / MRI is length x breadth x height x 0.523, which assumes that most structures are ellipsoid (like an ellipsoid). Cc and ml are used interchangeably, especially for prostate. I like to use cc as that is the true measurement.
A few modifications of these formulae have been developed and integrated into the above formula. The above calculator has formulae for calculating the following:
Generic volume calculator
- Calculate the volume of abscesses.
- Ovarian volume calculator (useful for ultrasound diagnosis of polycystic ovaries). In patients with PCOD/PCOS (Polycystic ovarian syndrome/disease) the ovarian volumes are usually more than 10cc. Check the examples below
- Calculate the volume of ovarian cysts.
- Volume of benign and malignant masses.
- Calculate the volume for other lesions that have a somewhat ellipsoid shape.
- Calculate volume of spleen. This can be used to monitor spleen size in patients with lymphoma and is a better measurement than single dimensions.
Bladder volume calculator
Calculate pre- and post-void bladder volumes on ultrasound – useful to rule out urinary retention). A post void volume of more than 50-100ml is significant.
Prostate volume calculator for ultrasound and MRI. Includes PSA density measurements.
Prostate volume is usually less than 30cc. You can grade mild, moderate and marked prostatomegaly for volumes 30-50,50-70 and +70cc respectively.
PSA density is a better measure than PSA alone to gauge the risk of prostate cancer. It is calculated by dividing the PSA by the prostate volume.
Although the cut-off values vary, most papers suggest a cut-off value of 0.15-0.20 above which there is a high chance of the patient having clinically significant prostate cancer.
Thyroid volume calculator.
Mean thyroid volume in adults is 7-10cc. It can be smaller in patients with hypothyroidism and more in patients with goiter and thyroiditis.
Testicular volume calculator.
Testicular volume is age dependent. The testis measure approximately 4cc in volume at puberty. Normal testicular volume in adult male patients is 12-30ml. Volume decreases as the patient gets older. Smaller volumes can be seen in patients with testicular atrophy.
Renal volume calculator:
Normal adult kidney is approximately 11 ± 1.0 cm long, with a normal volume of 110 to 190 ml in men and 90 to 150 ml in women. Renal volume is especially important in ADPKD patients. Read this article to find out why: ADPKD : What else the radiologist MUST report!
For prostate volume, the bullet shape formula is found to be more accurate as compared to the ellipsoid formula. However, PIRADS 2.1 still recommends the ellipsoid formula, so we have kept it the same.
Also, do read our article on normal radiological measurements and reference values:
- Improving ultrasound-based prostate volume estimation
- Testicular volume measurement: comparison of ultrasonography, orchidometry, and water displacement.
- A simple method to estimate renal volume from computed tomography
- Thyroid Volume and Its Relation to Anthropometric Measures in a Healthy Cuban Population