The accuracy of Multi-detector row CT for the assessment of tumor invasion of the mesorectal fascia in primary rectal cancer

PURPOSE: To evaluate the accuracy of Multi-detector row CT (MDCT) for the prediction of tumor invasion of the mesorectal fascia (MRF). MATERIALS AND METHODS: A total of 35 patients with primary rectal cancer underwent preoperative staging magnetic resonance imaging (MRI) and MDCT. The tumor relationship to the MRF, expressed in 3 categories (1--tumor free MRF = tumor distance > or = 1 mm; 2--threatened = distance < 1 mm; 3--invasion = distance 0 mm) was determined on CT by two observers at patient level and at different anatomical locations. A third expert reader evaluated the MRF tumor relationship on MRI, which served as reference standard. Receiver operating characteristic curves (ROC-curves) and areas under these curves (AUC) were calculated. The inter-observer agreement of CT was determined by using linear weighted kappa statistics. RESULTS: The AUC of CT for MRF invasion was 0.71 for observer 1 and 0.62 for observer 2. The inter-observer agreement was kappa = 0.34. The performance of CT at mid-high rectal levels was statistically significant better compared to low anterior (obs.1: AUC = 0.88 vs. 0.50; obs 2: AUC = 0.84 vs. 0.31; P < or = 0.040). CONCLUSION: Multi-detector row CT has a poor accuracy for predicting MRF invasion in low-anterior located tumors.The accuracy of CT significantly improves for tumors in the mid-high rectum. There is a high inconsistency among readers

Preoperative rectal cancer staging with phased-array MR

<p>Abstract</p> <p>Background</p> <p>We retrospectively reviewed magnetic resonance (MR) images of 96 patients with diagnosis of rectal cancer to evaluate tumour stage (T stage), involvement of mesorectal fascia (MRF), and nodal metastasis (N stage).</p> <p>Our gold standard was histopathology.</p> <p>Methods</p> <p>All studies were performed with 1.5-T MR system (Symphony; Siemens Medical System, Erlangen, Germany) by using a phased-array coil. Our population was subdivided into two groups: the first one, formed by patients at T1-T2-T3, N0, M0 stage, whose underwent MR before surgery; the second group included patients at Tx N1 M0 and T3-T4 Nx M0 stage, whose underwent preoperative MR before neoadjuvant chemoradiation therapy and again 4-6 wks after the end of the treatment for the re-staging of disease.</p> <p>Our gold standard was histopathology.</p> <p>Results</p> <p>MR showed 81% overall agreement with histological findings for T and N stage prediction; for T stage, this rate increased up to 95% for pts of group I (48/96), while for group II (48/96) it decreased to 75%.</p> <p>Preoperative MR prediction of histologically involved MRF resulted very accurate (sensitivity 100%; specificity 100%) also after chemoradiation (sensitivity 100%; specificity 67%).</p> <p>Conclusions</p> <p>Phased-array MRI was able to clearly estimate the entire mesorectal fat and surrounding pelvic structures resulting the ideal technique for local preoperative rectal cancer staging.</p

Value of MRI and diffusion-weighted MRI for the diagnosis of locally recurrent rectal cancer

OBJECTIVES: To evaluate the accuracy of standard MRI, diffusion-weighted MRI (DWI) and fusion images for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence. METHODS: Forty-two patients with a clinical suspicion of recurrence underwent 1.5-T MRI consisting of standard T2-weighted FSE (3 planes) and an axial DWI (b0,500,1000). Two readers (R1,R2) independently scored the likelihood of recurrence; [1] on standard MRI, [2] on standard MRI+DWI, and [3] on T2-weighted+DWI fusion images. RESULTS: 19/42 patients had a local recurrence. R1 achieved an area under the ROC-curve (AUC) of 0.99, sensitivity 100% and specificity 83% on standard MRI versus 0.98, 100% and 91% after addition of DWI (p = 0.78). For R2 these figures were 0.87, 84% and 74% on standard MRI and 0.91, 89% and 83% with DWI (p = 0.09). Fusion images did not significantly improve the performance. Interobserver agreement was kappa0.69 for standard MRI, kappa0.82 for standard MRI+DWI and kappa0.84 for the fusion images. CONCLUSIONS: MRI is accurate for the diagnosis of locally recurrent rectal cancer in patients with a clinical suspicion of recurrence. Addition of DWI does not significantly improve its performance. However, with DWI specificity and interobserver agreement increase. Fusion images do not improve accuracy

Local staging of rectal cancer: the current role of MRI

With the advent of powerful gradient coil systems and high-resolution surface coils, magnetic resonance imaging (MRI) has recently extended its role in the staging of rectal cancer. MRI is superior to endorectal ultrasound, the most widely used staging modality in patients with rectal tumors, in that it visualizes not only the intestinal wall but also the surrounding pelvic anatomy. The crucial advantage of MRI is not that it enables exact T-staging but precise evaluation of the topographic relationship of a tumor to the mesorectal fascia. This fascia is the most important anatomic landmark for the feasibility of total mesorectal excision, which has evolved into the standard operative procedure for the resection of cancer located in the middle or lower third of the rectum. MRI is currently the only imaging modality that is highly accurate in predicting whether or not it is likely that a tumor-free margin can be achieved and thus provides important information for planning of an effective therapeutic strategy, especially in patients with advanced rectal cancer

Magnetic resonance imaging (MRI) in rectal cancer: a comprehensive review

Magnetic resonance imaging (MRI) has established itself as the primary method for local staging in patients with rectal cancer. This is due to several factors, most importantly because of the ability to assess the status of circumferential resection margin. There are several newer developments being introduced continuously, such as diffusion-weighted imaging and imaging with 3 T. Assessment of loco-regional lymph nodes has also been investigated extensively using different approaches, but more work needs to be done. Finally, evaluation of tumours during or after preoperative treatment is becoming an everyday reality. All these new aspects prompt a review of the most recent advances and opinions. In this review, a comprehensive overview of the current status of MRI in the loco-regional assessment and management of rectal cancer is presented. The findings on MRI and their accuracy are reviewed based on the most up-to-date evidence. Optimisation of MRI acquisition and relevant regional anatomy are also presented, based on published literature and our own experience

Cross-sectional imaging for local staging of rectal cancer

Cross-sectional imaging plays a key role in the local staging of rectal cancer. The two main goals of imaging are to classify patients into differentiated tumour risk profiles for neoadjuvant treatment stratification and to provide an anatomical roadmap of the tumour for detailed planning of the surgical resection strategy. In many countries, MRI is considered the modality of the first choice for local staging of rectal cancer. Strengths of MRI include its ability to accurately stratify high-risk T3 and T4 tumours and to assess tumour invasion into important surgical landmarks including the mesorectal fascia and anal sphincter. CT should only be considered as an alternative for local staging in upper rectal tumours (close to the rectosigmoid junction) or in case of limited availability or contraindications for MRI. Restaging with imaging has recently gained clinical significance due to the shift in treatment towards organ-preserving treatments for patients that respond very well to neoadjuvant treatment. In this setting, use of anatomical MRI to detect and stage any residual tumour is limited by the presence of fibrosis, and the addition of functional imaging (diffusion-weighted MRI) helps to improve the performance of MRI