Radiology Volume Calculator
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Overview:
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). 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).
- Calculate the volume of ovarian cysts.
- Mass lesion volume.
- 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 (to calculate pre- and post-void bladder volumes on ultrasound – useful to rule out urinary retention).
- Prostate volume calculator for ultrasound and MRI. Includes PSA density measurements
- Thyroid volume calculator.
- Testicular volume calculator.
- Renal volume calculator: 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.
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.
Also, do read our article on normal radiological measurements and reference values:
References:
- 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
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Do note that these values are reference purposes only and may not be accurate. Each institution has its own policy and readers are encouraged to follow those. Also, these values have to be interpreted in the appropriate clinical context. The authors cannot be held liable for any mistake of harm resulting from the use of this website or its content.
Dr. Amar Udare, MD, DNB
Dr. Amar Udare is a board-certified radiologist. He is a clinical assistant professor at the University of Calgary. He has a passion for teaching (#FOAMrad and #FOAMed) and has been a semi-finalist for the 2018 and 2020 Aunt-Minnie Most effective Radiology Educator Awards. He has authored multiple peer-reviewed publications which can be accessed on PubMed and Google Scholar.