Purpose

To evaluate multidetector computed tomography (MDCT) performance in the preoperative local staging in colon cancer, focusing on the differentiation between T3ab from T3cd/T4 disease.

Material and methods

In this retrospective study, preoperative MDCTs of 33 patients with colon adenocarcinoma were evaluated regarding T (T3ab, T3cd and T4) and N staging (N0/N+) by two observers blinded to each other’s readings and to the pathological reports. Results were compared with histopathology (gold standard) and sensitivity, specificity and accuracy were calculated. Interobserver agreement was compared using κ statistics.

Results

MDCT had high sensitivity in the differentiation between T3ab and T3cd/T4 tumors (81,5-85,2%) but moderate specificity (50%) and moderate interobserver agreement was observed (ĸ=0,57).

In the detection of lymph node metastases, MDCT showed a moderate to high sensitivity (61,5-84,6%), moderate specificity (57,1%) and an accuracy of 60,6-78,8%. Interobserver agreement was moderate (ĸ=0,58).

Conclusion

Differentiation between early and locally advanced colon cancers with MDCT is challenging, particularly regarding nodal staging. This may have considerable clinical impact in the future if neoadjuvant treatment for locally advanced colon cancers becomes standard.

Purpose

To assess the interobserver variability in MRI measurements of mesorectal invasion depth (MID) in rectal adenocarcinomas primarily staged as T3, by determining the level of interobserver agreement in the differentiation of individual T3 substages and of T3ab vs T3cd disease.

Material and methods

A retrospective analysis of 60 patients classified by MRI as having T3 rectal cancers was performed. Each patient underwent MR examination in a 1.5T machine and the standard imaging protocol included a high-resolution axial T2-weighted sequence in which the measurements were determined by independent radiologists (readers A and B, with 15 years and 1 year of experience, respectively). The rectum was further divided into quadrants and each reader selected the quadrant where the measurement was taken. The patients were grouped according to the MID (T3a < 1mm; T3b 1-5mm; T3c > 5-15mm; T3d > 15mm) and the interobserver reliability was tested using Cohen’s kappa.

Results

Population included 40 males and 20 females with a median age of 65,9 years. Interobserver agreement on individual substage differentiation (T3 a, b, c and d) was moderate (K=0.428) and in the quadrant evaluation the level of agreement was also moderate (K=0.414). Nevertheless, the interobserver reliability for the differentiation between stages T3ab vs T3cd was good (K=0.697).

Conclusion

There is no considerable interobserver variability when distinguishing T3ab from T3cd tumors, regardless of the quadrant where the MID is measured. Therefore, assessment of MID, for that purpose, is a reproducible MR parameter, irrespectively of the readers’ experience.

Learning objectives