Understanding Your Prostate MRI or TRUS Report: A Patient's Guide

July 19, 2026

A prostate MRI or TRUS report is written for the referring physician, not the patient, which is why it can look like a wall of abbreviations at first glance. This guide walks through what to look for and how to turn it into a volume and PSAD estimate using the prostate volume calculator.

Step 1 — Find the Three Dimension Measurements

Look for a line reporting three measurements in centimeters, usually labeled something like “AP × TR × CC” (anteroposterior × transverse × craniocaudal) or simply listed as three numbers with a volume calculation already shown. These three numbers are exactly the length, width, and height the ellipsoid formula needs — the report’s own labels don’t need to match “length/width/height” exactly, since all three measurements plug into the same formula regardless of which axis label is used for which number.

Step 2 — Confirm the Units

Radiology reports overwhelmingly use centimeters, but double-check before entering numbers — a measurement that looks unusually small or large for a prostate gland (typical adult range is roughly 20-40cc in volume, corresponding to length/width/height each usually in the 3-5cm range) is a signal to re-check whether the report used a different unit. The prostate volume calculator’s unit toggle handles inches automatically if a source does report in inches.

Step 3 — Check Whether the Report Already Lists a Volume

Many reports calculate and print the ellipsoid volume directly, sometimes alongside the coefficient used (0.52 vs. the more precise π/6 ≈ 0.523). If a report’s stated volume doesn’t match what the prostate volume calculator produces from the same three dimensions, the difference is almost always this coefficient rounding — a small, clinically insignificant gap, not an error.

Step 4 — Locate the PSA Value (Usually on a Separate Lab Report)

PSA is a blood test, so it typically won’t appear on the imaging report itself — check the most recent lab results instead. Enter that value alongside the calculated volume to get PSA density (PSAD), and compare it against the 0.15 and 0.20 reference thresholds explained on the prostate volume calculator.

Step 5 — Look for a PI-RADS Score if the Report Is From an MRI

If the imaging was an MRI (rather than TRUS), the report may also include a PI-RADS score (1 to 5) for any specific lesion identified — this is a separate assessment from prostate volume and PSAD, describing how suspicious a specific area looks rather than the gland’s overall size. See the BPH & PSA glossary for what each PI-RADS number means.

Step 6 — Note Whether Transition Zone Volume Is Reported Separately

Some MRI reports break out a separate “transition zone volume” in addition to total gland volume, since BPH growth concentrates in this specific region. If both are listed, the prostate volume calculator’s standard PSAD calculation uses total gland volume — a transition-zone-specific PSAD is a more specialized calculation your urologist may reference separately.

Step 7 — Bring Questions, Not Conclusions, to Your Follow-Up

A calculated volume or PSAD from this process is a useful starting point for a conversation with a urologist, not a self-diagnosis. If a number looks concerning, write down the specific figures and reference range from the report and calculator, and bring them to the follow-up appointment rather than searching for a standalone interpretation — PSAD is only one factor among several (PSA velocity, free/total PSA ratio, PI-RADS, family history) that go into any actual clinical decision.

Bottom Line

Look for three cm measurements (often labeled AP/TR/CC), the most recent PSA lab value, and — for MRI reports — a PI-RADS score if a specific lesion was flagged. Enter the dimensions and PSA into the prostate volume calculator to reproduce or double-check the report’s own volume and PSAD figures, and review the common calculation mistakes if a number looks unexpectedly different from a prior report.