MRI in Colorectal Surgery: Endoluminal MR Imaging of Anorectal Diseases
Endoluminal MRI is in many aspects superior to body coil MRI and in some aspects superior to external phased array MRI and endosonography. The latter primarily concerns the evaluation of EAS atrophy in fecal incontinence. When an EAS defect diagnosed at endosonography is considered for surgical repair, then an endoluminal MRI should be performed (where available) to exclude substantial external sphincter atrophy. Until now, no data are available on external phased array MRI in fecal incontinence. In perianal fistulas, endoanal MRI is preferable in cryptoglandular fistulas, while in Crohn’s disease, preliminary evidence suggests a benefit in external phased array coil MRI. The limitations in endoanal probe technology for some important questions in complex perirectal sepsis still apply and have been outlined in this chapter; however, Gadolinium or saline enhancement will readily distinguish residual or recrudescent sepsis from burnt-out scar tissue. In rectal cancer, endorectal MRI has not been demonstrated to be superior to endosonography or external phased array MRI, and its role appears limited. Unfortunately, it has not proven useful in the differentiation between T1 and T2 tumors despite high resolution of the soft tissues, and therefore it cannot enhance surgical decision making regarding curative TEMS. The use of endoluminal MRI might be advantageous in anal tumors for determining depth of infiltration; however, until now, no study has sufficiently evaluated endoluminal MRI in this condition.
KeywordsFecal Incontinence Anal Sphincter External Anal Sphincter Anorectal Disease Coil Magnetic Resonance Imaging
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