Preoperative Staging of Rectal Tumors: Comparison of Endorectal Ultrasound, Hydro-CT, and High-Resolution Endorectal MRI

Abstract

Aim: The aim of this study was to compare transrectal ultra-sound (TRUS), hydro-computed tomography (hydro-CT), and endorectal magnetic resonance imaging (MRI) in the preoperative staging of rectal cancer. Patients and Methods: 23 patients with rectal adenocarcinoma underwent TRUS, hydro-CT, and MRI (1 Tesla) with endorectal coil. The results were correlated with the histopathological findings based on the TNM classification. Results: T staging with TRUS, hydro-CT, and endorectal MRI correlated with the histopa-thological findings in 83% of patients (19/23). Tumors were overestimated by TRUS in 2/23 patients, by CT in 3/23, and by MRI in 3/23 patients. Tumor size was underestimated by TRUS in 2 patients, by CT and MRI in 1 case each. Local lymphatic node involvement was correctly diagnosed with CT and MRI in 87% and 83%, respectively. Using TRUS, false-negative results in the staging of lymph node involvement were seen in 3/23 patients, whereas 1 patient was over-staged. Using hydro-CT as well as endorectal MRI, overstaging of the local lymph nodes took place in 2/23 patients. Conclusion: All methods are limited because peritumoral inflammation cannot be precisely distinguished from infiltration by the tumor. Correct lymph node staging is hampered in advanced disease using TRUS. In these patients, further cross-sectional imaging may be required.

Overstaging: A Challenge in Rectal Cancer Treatment

“…These findings were quite in line with a study conducted by Dinter et al [27], which reported overstaging by Hydro-CT in 3/23 (13%) patients. However, low accuracy in detecting T1/2 lesions and nodal staging posed significant restrictions [27].…”

“…These findings were quite in line with a study conducted by Dinter et al [27], which reported overstaging by Hydro-CT in 3/23 (13%) patients. However, low accuracy in detecting T1/2 lesions and nodal staging posed significant restrictions [27]. More recent studies reported accuracies of up to 87% for T staging and 80% for N staging by MDCT with multiplanar reconstruction [7,28,29].…”

Endoscopic ultrasound and magnetic resonance imaging forre-staging rectal cancer after radiotherapy

“…Recent data suggest that EUS staging of rectal cancer after RT-CT is inaccurate [1] , while MRI seems to be costeffective in selecting appropriate patients for neoadjuvant therapy and its use is justified for local staging. After RT-CT, EUS and MRI might be useful to demonstrate tumor shrinkage and down-staging in responsive tumors, which might occasionally disappear completely [17,18,[20][21][22][23] . Increasing reflectivity and signal changes indicate fibrosis, but unless significant tumor bulk remains, neither modality seems to be able to exclude the persistence of tumor cells within fibrosis [24][25][26][27][28] .…”

EUS-FNA assessment of extramesenteric lymph node status in primary rectal cancer

“…38 Although rigid endoscopic rectal US effectively predicts levator ani muscle or external anal sphincter invasion, it does not have the ability to adequately evaluate more proximal tumors, regions beyond the field of TME or the facility to sample lymph nodes under real-time guidance. [39][40][41][42][43] Nodal metastasis is an independent poor prognostic indicator in patients with rectal cancer. It would appear that individuals with EMLNM may be a distinct subgroup at increased risk of local recurrence and worse prognosis.…”