Relevance of magnetic resonance imaging-detected pelvic sidewall lymph node involvement in rectal cancer.

BACKGROUND: The significance of magnetic resonance imaging (MRI)-suspected pelvic sidewall (PSW) lymph node involvement in rectal cancer is uncertain. METHODS: Magnetic resonance images were reviewed retrospectively by specialist gastrointestinal radiologists for the presence of suspicious PSW nodes. Scans and outcome data were from patients with biopsy-proven rectal cancer and a minimum of 5 years' follow-up in the Magnetic Resonance Imaging and Rectal Cancer European Equivalence Study. Overall disease-free survival (DFS) was analysed using the Kaplan-Meier product-limit method and stratified according to preoperative therapy. Binary logistic regression was used to match patients for propensity of clinical and staging characteristics, and further survival analysis was carried out to determine associations between suspicious PSW nodes on MRI and survival outcomes. RESULTS: Of 325 patients, 38 (11·7 per cent) had MRI-identified suspicious PSW nodes on baseline scans. Such nodes were associated with poor outcomes. Five-year DFS was 42 and 70·7 per cent respectively for patients with, and without suspicious PSW nodes (P < 0·001). Among patients undergoing primary surgery, MRI-suspected PSW node involvement was associated with worse 5-year DFS (31 versus 76·3 per cent; P = 0·001), but the presence of suspicious nodes had no impact on survival among patients who received preoperative therapy. After propensity matching for clinical and tumour characteristics, the presence of suspicious PSW nodes on MRI was not an independent prognostic variable. CONCLUSION: Patients with suspicious PSW nodes on MRI had significantly worse DFS that appeared improved with the use of preoperative therapy. These nodes were associated with adverse features of the primary tumour and were not an independent prognostic factor.

Accuracy of liver-specific magnetic resonance imaging as a predictor of chemotherapy-associated hepatic cellular injury prior to liver resection.

BACKGROUND/AIMS: To evaluate the diagnostic precision of chemical-shift imaging MRI and ferucarbotran-enhanced MRI for hepatic parenchymal injury prior to hepatic resection for colorectal metastases. METHODS: Preoperative MRI criteria were used to score 37 patients with colorectal liver metastases by two independent radiologists, blinded to outcomes, for signal drop-out on chemical-shift imaging MRI and ferucarbotran uptake and compared to blinded standardized histopathological endpoints of steatosis, steatohepatitis and sinusoidal dilatation. Sensitivity, specificity, predictive values and the area under the receiver operating characteristic curve (AUC) were calculated for the MRI sequences. RESULTS: On histology, severe steatosis, steatohepatitis and sinusoidal dilation were evident in 6 (16.2%), 4 (10.8%) and 9 (24.3%) patients respectively. Chemical-shift imaging MRI had a positive predictive value (PPV) of 100% for severe steatosis, 80% for steatohepatitis and zero for sinusoidal dilatation, with an AUC of 1.0, 0.99 and 0.36 respectively. Ferucarbotran-enhanced MRI had a 100% PPV for the detection of severe sinusoidal dilatation, with an AUC of 0.61. CONCLUSIONS: This study demonstrates that liver-specific MRI can accurately predict the severity of pre-existing hepatic injury. Moreover, it may play a key role in planning the timing and extent of chemotherapy and hepatic resection for colorectal metastases.

Techniques and trouble-shooting in high spatial resolution thin slice MRI for rectal cancer.

MRI is increasingly advocated as an optimal method of staging rectal cancer. The technique enables depiction of the relationship of tumour to the mesorectal fascia and may thus identify tumours at risk of positive circumferential margin involvement at surgery. Depth of extramural spread may also be accurately measured and tumour deposits within the mesorectum are shown. It is important that a high spatial resolution technique is used in order to accurately depict these features and care should be taken in ensuring that images acquired cover the entire rectal tumour and mesorectum. This paper describes the technique of high spatial resolution rectal cancer imaging and the potential technical pitfalls in acquiring good quality images. Important factors to consider include: adequate scan duration to achieve high spatial resolution images with sufficient signal to noise ratio, careful positioning of the pelvic phased array coil, use of T2 weighted turbo spin-echo rather than T1 weighted imaging and careful planning of scans to ensure that images are obtained perpendicular to the rectal wall.