Table 1.
MRI measurement names and their definitions.
| Item | Feature | Abbreviation | Definition |
|---|---|---|---|
| Sagittal plane | Membranous urethral length | MUL | The distance from the top of prostate to the bottom of the bulbar urethra |
| Membranous urethral Angle | MUA | An obtuse angle obtained by crossing a horizontal line under the pubic symphysis and a straight line parallel to the membranous urethra | |
| Prostate length | PL | The maximum height of the prostate measured from the base of the prostate to the apex in any plane | |
| Pubic symphysis-prostate apex length | PAL | Refers to the distance between the sagittal line of the prostatic crest and the prostatic crest line, and the vertical distance between the horizontal extension line of the suprapubic crest line and the horizontal extension line of the prostate apex. | |
| Axial plane | Thickness of left obturator internus muscle | TLOIM | The maximum thickness of left obturator muscle measured on any plane |
| Thickness of right obturator internus muscle | TROIM | The maximum thickness of right obturator muscle measured on any plane | |
| Prostate width | PW | The maximum prostate width measured at the same level as the maximum width | |
| Prostate height | PH | The maximum prostate height measured at the same level as the maximum width. | |
| Urethral width | UW | Defined as the maximum diameter of the urethra. | |
| Distance of outer of the levator ani muscle | DOLAM | Defined as the distance from the outer edge of the levator ani muscle measured at the same level as the distance from the levator ani muscle | |
| Distance of inner of the levator ani muscle | DILAM | Defined as the narrowest distance from the inner edge of levator ani muscle to the urethra below the tip tail edge of the prostate | |
| Transverse membranous urethral thickness | TMUT | Measure the transverse maximum thickness of membranous urethra at the penis root level | |
| Anterior and posterior membranous urethral thickness | APMUT | Measure the maximum longitudinal thickness of membranous urethra at the level of penis root | |
| Left anal sphincter thickness | LST | The maximum thickness of the left anal sphincter measured in any plane | |
| Right anal sphincter thickness | RST | The maximum thickness of the right anal sphincter measured in any plane | |
| Urethral wall thickness | UWT | The widest part of the membranous urethra in the axial sequence before entering the prostate. | |
| Coronal plane | Thickness of left levator ani muscle | TLLAM | The measured maximum thickness of left levator ani muscle. |
| Thickness of right levator ani muscle | TRLAM | The measured maximum thickness of right levator ani muscle. | |
| Calculated value | The thickness of levator ani muscle in axial plane | TLAM | The difference of DOLAM and DILAM divided by 2 |
| The cross section surface area of membranous urethra | CSAMU | Calculated based on the formula: (TMUT * 1/2) * (APMUT * 1/2)*π | |
| Prostate volume | PV | Calculated based on the following formula: PL * PH * PW *π/6 | |
| Membranous urethral volume | MUV | Calculated by the following formula: CSAMU * MUL |