Including video and novel parameter-height of penetration of external anal sphincter-in magnetic resonance imaging reporting of anal fistula

Table 1 Format for the written magnetic resonance imaging report

Parameters	Example
Primary tract	The primary fistula tract
External opening	Is opening in perianal skin at 7 o’clock position
Course and location	It extends superiorly in right ischiorectal fossa from 7 to 8 o’clock position
Length	For a length of 6.35 cm
Location and height of penetration of EAS (HOPE)	and penetrates the EAS at 8 o’clock position involving approximately two-thirds of the EAS. It then bends inferiorly and
Intersphincteric tract	follows an intersphincteric route from 8 to 6 o’clock
Location and height Internal opening	and opens in the anal canal at the level of dentate line
Secondary extension- intersphincteric/ ischiorectal fossa/supralevator	There are no secondary extensions of primary tract
Secondary tract	There are no secondary tracts,
External opening
Course and location
Associated abscess	No associated abscess
Supralevator or suprasphincteric tract	And supralevator tract
Sphincter anatomy	The sphincters look normally preserved
Classification	Parks grade -II, SJUH1 grade III

¹SJUH- St James’s University Hospital classification.

Report: The primary fistula tract is opening in perianal skin at 7 o’clock position. It extends superiorly in right ischiorectal fossa from 7 to 8 o’clock position for a length of 6.35 cm and penetrates the external anal sphincter (EAS) at 8 o’clock position involving approximately two-thirds of the EAS. It then bends inferiorly and follows an intersphincteric route from 8 to 6 o’clock and opens in the anal canal at the level of dentate line. There are no secondary extensions of primary tract. There are no secondary tracts, no associated abscess, and no supralevator tract. The sphincters look normally preserved. Impression- A right transsphincteric high fistula involving about two-thirds of the external anal sphincter, intersphincteric tract from 8 to 6 o’clock and internal opening at 6 o’clock at the level of dentate line. No secondary tract, abscess or supralevator extensions. Parks grade -II, SJUH grade III.

Table 2 Format for reporting the fistula magnetic resonance imaging in the video

Axial Section T2-weighted
1 External opening- location
2 Define primary tracts
Location and course – Ischiorectal fossa/ Intersphincteric and clock-dial position
Location and ‘height’ of penetration of external anal sphincter (HOPE)- Point of penetration of external anal sphincter
Intersphincteric course
Location and height of internal opening- clock-dial position and whether it is at dentate line or higher
3 Secondary tracts
4 Associated abscesses
5 Supralevator extension
6 Additional internal opening
7 Sphincter anatomy
Axial section-STIR
1 Confirm findings of Axial-T2
2 Additional areas with inflammation
Coronal T2-weighted
1 Confirm findings of Axial-T2
2 Length of tract
3 Supralevator or suprasphincteric tract
4 Confirm the ‘height’ of penetration of external anal sphincter (HOPE) by the fistula tract – Indicates the amount of external sphincter involved
5 Confirm the ‘height’ of the site of internal opening
6 Extent of fistula tract in anterior fistulas- relation with urethra
7 Sphincter anatomy
Coronal section- STIR
1 Confirm findings of Coronal-T2
2 Good to detect thin Intersphincteric collections
Biplanar (Axial T-2 weighted + Coronal T-2 weighted)
1 Confirm the ‘height’ of the site of penetration of external sphincter by the fistula tract – Indicates the amount of external sphincter involved
2 Confirm the ‘height’ of the site of internal opening
Sagittal section
1 Extent of fistula tract in posterior fistulas- Relation with sacrococcygeal spine, presacral space
2 Extent of fistula tract in anterior fistulas- Relation with urethra