Locally advanced rectal cancer: value of ADC mapping in prediction of tumor response to radiochemotherapy.

To evaluate the diagnostic performance of quantitative apparent diffusion coefficient (ADC) measurements, in the assessment of the therapeutic response to chemo-radiation therapy (CRT) in patients with locally advanced rectal cancer, by analyzing post CRT values of ADC, in relation to tumor regression grade (TRG) obtained by histopathologic evaluation of the rectal specimen. This prospective study was approved by an Institutional Review Board, and informed consent was obtained from all patients. Thirty-one patients with locally advanced rectal cancer underwent pre and post CRT MR imaging at 1.5T. ADC values were measured in regions of interest (ROIs) drawn independently by two radiologists, blinded to the pathology results, on three slices of the pre and post CRT DW-MR image sets with the corresponding T2 weighted images (T2WI) available for anatomic reference. The two readers' measurements were compared for differences in ADC values, inter-observer variability (measured as the intraclass correlation coefficient; ICC) and the ADC distributions of responders vs non-responders. The diagnostic performance of ADC in the prediction of the response to CRT was evaluated by calculating the area under the ROC curve (AUC) and the optimal cut-off values. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were assessed. The two readers showed an overall strong agreement in measuring ADC values. For both readers, no differences in ADC pre-treatment measurements were observed between responders and non-responders. For reader 1, the post-CRT ADC and the ΔADC presented the higher AUC (0.823 and 0.803, respectively), while Δ%ADC provided the lower AUC value (0.682). The optimal cutoff point was 1.294 s/mm(2) for post-CRT measures (sensitivity=86.4%, specificity=66.7%, PPV=86.4%, NPV=66.7%), 0.500 for ΔADC (sensitivity=81.8%, specificity=66.7%, PPV=85.7%, NPV=60.0%) and 59.3% for Δ%ADC (sensitivity=63.4%, specificity=66.7, PPV=82.4%, NPV=42.9%). Similar results were observed for reader 2, with better performance obtained with the ADC post-CRT (AUC of 0.833) and an optimal cut off of 1.277 × 10(-3)s/mm(2). Post-CRT ADC measurements are reliable and reproducible and may be used as a non-invasive tool to evaluate response to therapy as post-CRT ADC values and ΔADC presented good diagnostic performance to select responder patients.

Monguzzi L ，Ippolito D ，Bernasconi DP ，Trattenero C ，Galimberti S ，Sironi S ... -  《-》

Rectal cancer: assessment of complete response to preoperative combined radiation therapy with chemotherapy--conventional MR volumetry versus diffusion-weighted MR imaging.

Curvo-Semedo L ，Lambregts DM ，Maas M ，Thywissen T ，Mehsen RT ，Lammering G ，Beets GL ，Caseiro-Alves F ，Beets-Tan RG ... -  《-》

Comparison of diffusion-weighted MRI and MR volumetry in the evaluation of early treatment outcomes after preoperative chemoradiotherapy for locally advanced rectal cancer.

To compare diffusion-weighted imaging (DWI) and magnetic resonance (MR) volumetry for predicting treatment outcomes of locally advanced rectal cancers with preoperative chemoradiotherapy (CRT). This prospective study was approved by our Institutional Review Board. Thirty-four patients underwent three MR examinations: pre-CRT (before CRT), early CRT (2 weeks after CRT initiation), and post-CRT (before surgery). The tumor apparent diffusion coefficient (ADC), ADC increase rate, and volume reduction rate were compared between responders and nonresponders using three reference standards: downstaging, modified Response Evaluation Criteria in Solid Tumors (mRECIST), and tumor regression grade (TRG). For DWI and volumetry, differences between responders and nonresponders were assessed by receiver operating characteristic analysis. The median early tumor volume reduction rate of responders, subgrouped by downstaging and mRECIST (47.97% and 53.97%, respectively), was significantly higher than that of nonresponders (20.94% and 20.36%; P = 0.0024 and 0.0001, respectively), but there were no significant differences in pre-CRT ADC and early ADC increase rate using all references. When using the downstaging and mRECIST, the diagnostic performance of early tumor volume reduction rate (Az = 0.81 and 0.94, respectively) was higher than that of pre-CRT ADC (Az = 0.55 and 0.62; P = 0.033 and 0.007) and early ADC increase rate (Az = 0.58 and 0.64; P = 0.055 and 0.01) for predicting the treatment outcome. For TRG, there were no significant differences between DWI and volumetry. Early tumor volume reduction rate at the second week after CRT initiation may be a better indicator than DWI based on the mean ADC measurements for predicting CRT treatment outcome.

Kim YC ，Lim JS ，Keum KC ，Kim KA ，Myoung S ，Shin SJ ，Kim MJ ，Kim NK ，Suh J ，Kim KW ... -  《-》

Diffusion-weighted MRI and MR- volumetry--in the evaluation of tumor response after preoperative chemoradiotherapy in patients with locally advanced rectal cancer.

To determine the diagnostic performance of diffusion-weighted MRI and MR volumetry for the assessment of tumor response after preoperative chemoradiotherapy (CRT) in patients with locally advanced rectal cancer. Forty-three patients with rectal cancer who underwent preoperative CRT were prospectively examined for the study. This prospective study was approved by our institutional review board. DW- and high resolution T2-weighted imaging were performed before and after therapy. Two different diffusion gradients (b = 0 and b = 600, then separately b = 0 and b = 1000) were applied. The mean tumor volume and mean ADC values were measured before and after therapy. To evaluate the responders and nonresponders to neoadjuvant CRT, two criteria, ypT stage determined in the pathologic examination after treatment and histopathologic tumor regression grade (Ryan), were used as reference standards. The patients with a lower ypT stage than T stage in the first MRI before neoadjuvant CRT were evaluated as the responder group, while the patients with a higher or the same ypT stage relative to the first MRI T stage were evaluated as the nonresponder group. According to Ryan tumor regression grade, grade 1 was evaluated as the responders, whereas grades 2 and 3 were evaluated as the nonresponder group. The percentage ADC increase and percentage tumor volume regression were compared between the responders and nonresponders using two reference standards: T downstaging and tumor regression grade (TRG). Before CRT, the mean tumor ADC in the responder group was significantly lower than that in the nonresponder group (p < 0.001). At the end of CRT, the mean percentage of tumor ADC change in the responder group was significantly higher than that in the nonresponder group. The percentage tumor volume regression of the responders was significantly higher than that of the nonresponders (p = 0.001). The cut-off ADC value for discriminating between the responders and nonresponders after treatment was determined to be (b = 600) 1.03 × 10(-3)mm(2)/s and the sensitivity, 71%; specificity, 79%; accuracy, 74%; positive predictive value, 81%; negative predictive value, 68% respectively. The cut-off value for discriminating between the responders and the nonresponders after treatment was determined for b = 1000 as 1.20 × 10(-3)mm(2)/s and the sensitivity, 42%; specificity, 84%; accuracy, 60%; positive predictive value, 77%; negative predictive value, 53%. The increase in the mean tumor ADC and percentage tumor volume regression in patients with rectal cancer treated with preoperative CRT was correlated with good response. DW MR imaging is a promising non-invasive technique that can help predict and monitor early therapeutic response in patients with rectal cancer who undergo CRT.

Birlik B ，Obuz F ，Elibol FD ，Celik AO ，Sokmen S ，Terzi C ，Sagol O ，Sarioglu S ，Gorken I ，Oztop I ... -  《-》

Locally advanced rectal cancer: added value of diffusion-weighted MR imaging for predicting tumor clearance of the mesorectal fascia after neoadjuvant chemotherapy and radiation therapy.

Park MJ ，Kim SH ，Lee SJ ，Jang KM ，Rhim H ... -  《-》