How to improve MRI accuracy in detecting deep infiltrating colorectal endometriosis: MRI findings vs. laparoscopy and histopathology.

OBJECTIVE: To verify whether the capability of magnetic resonance imaging (MRI) in diagnosing deep infiltrating colorectal endometriosis (DICE) is improved using an association of MRI findings. METHODS AND MATERIALS: The imaging database of our Institute of Radiology was retrospectively reviewed to identify patients subjected to MRI for a suspicion of deep infiltrating endometriosis. Medical history was then investigated and only patients who were also subjected to laparoscopy (LA) were included. Absence of LA represented the exclusion criterion. Images were evaluated twice by two radiologists using two different diagnostic criteria for an abnormal result: the contemporary presence of nodules or hypointense plaque-like lesions in the adjacent fat plane and bowel wall thickness, without (first criterion) or with (second criterion) semicircular shape (i.e. "radial and retracting shape"). Radiologists worked in consensus evaluating images in two separate sessions, using the first criterion in the first section and the second criterion in the second one. MRI results were compared with LA or histopathology as the gold standard by 2 × 2 tables and statistically analyzed (k statistics). Likelihood-ratio test was also performed, being independent from the prevalence of the disease. RESULTS: By consulting case sheets, 33/50 females (ranging age 24-39 years, mean age 32.2 years) who were subjected to MRI also underwent LA. Intestinal resection for DICE was performed in 11/33 patients; in 22/33 superficial intestinal foci, adhesions/nodules in the fat plane were simply removed. When the first criterion was applied, MRI agreement with histopathology or LA was poor (51.5 %) (k value = 0.20; p < 0.055), while it was improved (96.9 %) when using the second diagnostic criterion (k value = 0.93; p < 0.0000). Likelihood ratio was 1.375 (95 % CI 0.69-2.72) using the first and 22 (95 % CI 20.08-24.1) using the second criterion. CONCLUSION: The second criterion, or the joint presence of nodules or hypointense plaque-like lesions in the adjacent fat plane and bowel wall thickness showing "radial and retracting shape", improves MRI capability in DICE diagnosis. It can be considered an effective indicator of DICE on T2-weighted images at 1.5-T MRI, and can ensure the correct preoperative assessment of the disease for the best therapeutic procedure and treatment planning.

Utilidad de la resonancia magnética para caracterización de fístulas perianales / Utility of the magnetic resonance for characterization of perianal fistulas

Objetivo: Comunicar nuestra experiencia en la caracterización de las fistulas perianales mediante hallazgos de resonancia magnética (RM). Métodos: Entre enero de 2007 y enero del 2008 se estudiaron 17 pacientes (1 mujer y 16 varones, promedio 42,6 años) con diagnóstico clínico de fístula perianal. Se realizó RM del periné con equipo Siemens 1.5 Tesla y bobina de superficie de cuerpo (Body Array) utilizando las secuencias: a) T2 Turbo-spin-echo axial, coronal y sagital; b) T2 supresión grasa axial; c) T1 supresión grasa axial, coronal y oblicuos siguiendo el trayecto fistuloso principal. Se catalogó a los trayectos fistulosos siguiendo la Clasificación de fístulas perianales para RM utilizada por el Hospital Universitario Saint James. Resultados: En los pacientes evaluados se observó: a) Trayecto fistuloso: interesfinteriano simple n=3 (17,7%); interesfinteriano con absceso interesfinteriano o trayecto fistuloso secundario n=0; transesfinteriano n=5 (29,4%); transesfinteriano con absceso o trayecto secundario dentro de la fosa isquioanal o isquiorrectal n=4 (23,5%); supraelevador y transelevador n=5 (29,4%), dos de ellos presentaron aspecto en herradura. El compromiso transesfinteriano se observó en 8 pacientes (47%) y Trans-supraelevador se identificó en 5 casos (29,4%) y fueron detectados abscesos en 5 (29,4%). b) Localización: izquierdas 4, derechas 9, anteriores 2 y posterior 2. Conclusiones: En todos los pacientes pudo identificarse el trayecto fistuloso principal, los secundarios y/o la presencia de abscesos. Esta técnica permitió una correcta caracterización de las fístulas perianales, pudiendo facilitar la elección del abordaje quirúrgico.

Objectives: to communicate our experience in the characterization of the perianal fistulas by means of the finds obtained by Magnetic Resonance. Methods: Between 01/ 2007 and 01/2008, 17 patient with clinical diagnosis of perianal fistulas were studied (1 woman and 16 males; mean age 42.6). Perineum MRI were performed with 1.5 Tesla Siemens and body surface coil (Body Array), using the sequences: a) T2-Turbo spin-echo in axial, coronal and sagittal plane; b) T2-fat sat axial sequence; c) T1-fat sat axial, coronal and oblique plane following the fistulous tract. They werecatalogued according to St. James’s University Hospital MRI Classification of perianal fistulas. Results: The evaluated patients showed: a) Fistulous Tract: inter-sphincteric fistula, n:3 (17.7%); inter-sphincteric fistula with associatedabscess cavitation or secondary fistulous tract, n:0; trans-sphincteric fistula, n:5 (29.4%); trans-sphincteric fistula with associated abscess cavitation or secondary tract within ischio-rectal or ischio-anal fossa, n:4 (23.5%); trans-elevator and supra-elevator, n:5 (29.4%), two of which presented Horseshoe-like tracts. Trans-sphincteric presentation was observed in 8 patients (47%), while trans-supraelevator presentation was observed in 5 cases (29.4%). Finally, abscess cavities were observed in 4 patients (29.4%). b) Location: left-sided (4), right-sided (6), anterior (2) and posterior (2). Conclusion: All fistulous tracts were detected, as well as the presence of associated abscesses. Ultimately, this method allowed us to adequately characterize perianal fistulas, helping surgeons in the preoperative assessment.