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Type:
Educational Exhibit
Keywords:
Abdomen, MR, Diagnostic procedure, Fistula
Authors:
S. Balci1, M. R. Onur2, A. D. Karaosmanoglu3, M. Karcaaltincaba3, D. Akata3, M. N. Özmen3; 1Artvin /TR, 2Ankara, Ankara/TR, 3Ankara/TR
DOI:
10.1594/ecr2017/C-1822
Background
Anal canal is anatomically defined as the end portion of gastrointestinal tract located between anal verge below and junction between anus and rectum above.
Dentate line is located near to mid-anal canal.
Anal canal musculature is composed of two muscle layers.
Internal sphincter is a smooth muscle which is actually continuation of circular gastrointestinal musculature.
External sphincter is a striated muscle,
controlled voluntarily,
it is the continuation of levator ani muscle.
Anal and perianal pathologies are radiologically best demonstrated with magnetic resonance imaging (MRI) owing to its high contrast resolution allowing accurate distinction of neighbouring soft tissues [1].
Both T2-weighted images obtained with fat saturation and T1-weighted images obtained after intravenous (IV) contrast administration are proposed as useful for ultimate diagnosis.
Postcontrast images are helpful for distinction between postoperative or chronic granulation - fibrotic tissue and active inflammation – abscess cavities [2].
One of the most essential requirement of anal and perianal MRI is accurate multiplanar orientation.
Since anal canal is obliquely oriented,
instead of true axial and coronal images; axial and coronal images should be standardized in each patient based on long axis of anal canal [2].