Clinical Application Of Magnetic Resonance Imaging In The Diagnosis, Staging And Neoadjuvant Therapy Of Rectal Cancer

ABSTRACT:Objective To evaluate the clinical value of diffusion-weighted imaging (DWI) combined with conventional sequences of magnetic resonance imaging (T1and T2-weighted imaging) for the diagnosis of rectal cancer. Methods DWI and conventional sequences were performed in29patients with endoscopically diagnosed rectal cancer and15patients without rectal cancer. Two doctors who were blind to the history of the patients interpreted the imaging findings. The sensitivity and specificity of conventional sequences with and without DWI were analyzed using receiver operating characteristic curve (ROC). Results The areas under ROC were0.915and0.930for conventional sequences alone, and0.990and0.994for conventional sequences with DWI, respectively, indicating that although both of them were optimal methods for the diagnosis of rectal cancer, the accuracy of conventional sequences with DWI was significantly superior to that of conventional sequence alone. The Kappa value was0.850for conventional sequences alone and0.858for DWI with conventional sequences. Conclusion DWI was necessary for the diagnosis of rectal cancer when performing conventional sequences. [Abstract] Objective This study was designed to investigate the accuracy of preoperative high-resolution magnetic resonance imaging scans to predict tumor stage, node stage and circumferential resection margin (CRM) involvement. Materials and Methods42patients with histologically proven carcinoma of the rectum were staged preoperatively using magnetic resonance imaging. All of the patients underwent totle mesorectum excision (TME) operation within1week after MRI examination. The specimens were reported according to the2002TNM staging system for primary colorectal cancer of the American Joint Committee on Cancer (AJCC). Agreement between radiologic staging of tumor, local lymph nodes and circumferential resection margin involvement, and pathologic reporting was assessed by means of the Kappa statistic. RESULTS:For all of the42patients, magnetic resonance imaging correctly staged the tumor in36patients, understaged in3, and overstaged in3. Statistically, there was good correlation between pathologic and radiologic tumor staging (Kappa=0.731, P=0.000). Magnetic resonance imaging correctly staged node status in27patients, understaged in6and overstaged in9. Statistically, there was common correlation between pathologic and radiologic node staging (Kappa=0.410, P=0.009). Magnetic resonance imaging correctly reported the status of the circumferential resecresection margin in40and overstaged in2. Statistically, there was good correlation between pathologic and radiologic reporting of circumferential resection margin involvement (Kappa=0.829, P=0.000). Results Preoperative high-resolution magnetic resonance imaging scans has a good agreement with pathologic tumor stage but common agreement with pathologic node stage. Preoperative high-resolution magnetic resonance imaging can provide reliable information about circumferential resection margins and thus help to choose which patient could benefit from the preoperative neoadjuvent therapy. [Abstract] Objective:To investigate the feasibility of diffusion-weighted magnetic resonance to monitor the response of rectal cancer to the preoperative neoadjuvant treatment by study the changes of the apparent diffusion coefficient (ADC) during the course of treatment. Material and methods:Diffusion weighted imagings were performed in7patients with primary rectal carcinoma who underwent preoperative neoadjuvent treatments for clinical staged T3No-2Mo. The ADC values and ADC histograms of the tumor were obtained prior to and in everyweek during the course of neoadjuvant treatment. Surgical resection of the tumors enabled the correlation of ADC values of the region of interest (ROI) with the pathologic classification. Results:4patients of downstaging and3patients of no downstaging were seen. In all patients, ADC values were higher before the onset of neoadjuvant treatment than to the end of the treatment. There was a significant increase in mean ADC over the downstagng group, while the mean ADC over the non-downstaging group decreased steadily. A significant decrease of ADC at the2nd,3rd,4th and5th week of the treatment was shown. Cytotoxic edema and fibrosis were believed to be the reasons for ADC decrease.Conclusion:This results showed that DWI is able to reflect the biological changes within the tumor tissure by monitoring the ADC changes during the course of neoadjuvant treatment.