Accuracy of MR Imaging in Preoperative Staging of Rectal Cancer

Abstract

Aim: In this study we aimed to evaluate the accuracy of preoperative rectal cancer staging in our center, using 1.0 Tesla Magnetic resonance imaging (MRI) with phased-array coils and determine if the results can be improved by adopting thin-section MRI techniques. Materal and Methods: Eighty-four patients with biopsy proven rectal cancer were prospectively evaluated by MRI using either the standard (8 mm sections in all planes) or the thin-section protocol (additional 5 mm sections in oblique axial plane perpendicular to the long axis of the tumor). Patients undergoing surgery with or without neoadjuvant therapy (standard MRI, n=15 and thin-section MRI, n=22) were included in the analysis. TNM stage, circumferential resection margin (CRM) and adjacent organ involvement were compared with histopathologic findings. Results: In the thin-section group, estimation of tumor stage was 59% accurate, showing fair agreement with histopathology (κ=0.38, p<0.05); sensitivity and specificity rates were 100% and 59% for T2 and 47% and 100% for T3 stages. In the standard group estimation of T stage was only 40% accurate, showing no significant agreement with histopathology. The most frequent staging error was under-staging of borderline pT3 tumors in both groups. Accuracy, sensitivity and specificity of positive CRM were 67%, 67% and 95% for thin-section group and 50%, 100% and 93% for standard group, respectively; agreement with histopathology was significant only for the thin-section group (κ=0.61; p<0.05). Accuracy of nodal status was 77% in the thin-section group (κ=0.51; p<0.05) and 87% in the standard group (κ=0.75; p<0.05). Conclusion: Thin-section MRI techniques can be used to improve tumor staging and positive CRM predictions even with low field magnet systems.

Keywords

• Magnetic Resonance Imaging
• Rectal Cancer
• Tumor Staging

Preoperatif Rektum Kanseri Evrelemesinde MR Görüntülemenin Doğruluğu

Abstract

Amaç: Bu çalışmada merkezimizde 1.0 Tesla Magnetik Rezonans (MR) cihazı ile faz dizilimli koil kullanarak preoperatif rektum kanseri evrelemesinin doğruluğunun değerlendirilmesi ve ince kesit MR teknikleri kullanarak sonuçların iyileştirilebilir olup olmadığının belirlenmesi amaçlanmıştır. Gereç ve Yöntem: Biyopsi ile rektum kanseri tanısı kanıtlanmış 84 hasta standart (tüm planlarda 8 mm kalınlığında kesitler) ya da ince kesit protokol (ek olarak tümörün uzun aksına dik 5 mm kalınlığında kesitler) kullanılarak Manyetik rezonans görüntüleme (MRG) ile prospektif olarak değerlendirilmiştir. Neoadjuvan tedavi alarak ya da almadan (standart MRG, n=15 ve ince kesit MRG, n=22) opere edilen hastalar analize dahil edilmiştir. TNM evrelemesi, çevresel rezeksiyon sınırı ve komşu organ tutulumu histopatolojik bulgular ile karşılaştırılmıştır. Bulgular: İnce kesit grubunda, tümör evresi histopatoloji (κ=0.38, p<0.05) ile %59 uyumlu, hassasiyet ve özgüllük ise T2 evresi için %100 ve %59, T3 evresi için %47 ve %100 doğruluktadır. Standart grupta T evresi histopatoloji ile anlamlı bir uyum göstermemekle birlikte yalnızca %40 doğruluktadır. İki grupta en sık evreleme hatası, sınırda pT3 tümörlerin düşük evrelenmesidir. Çevresel rezeksiyon sınırı pozitifliğinin doğruluk, duyarlılık ve özgüllüğü sırasıyla, ince kesit grubu için %67, %67 ve %95; standart grup için %50, %100 ve %93 tür. Bu sonuçlarda histopatoloji (κ=0.61; p<0.05) yalnızca ince kesit grubu için anlamlıdır. Nodal evrelemenin doğruluğu ince kesitli grupta %77 (κ=0.51; p<0.05) ve standart grupta %87 (κ=0.75; p<0.05) dir. Sonuç: İnce kesitli MRG teknikleri, düşük manyetik alan sistemlerde bile tümör evrelemesinin ve pozitif çevresel rezeksiyon sınırı tahminlerinin geliştirilmesi için kullanılabilir.

Keywords

• Manyetik Rezonans Görüntüleme
• Rektum Kanseri
• Tümör Evreleme

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