Locally advanced rectal cancer: MR imaging for restaging after neoadjuvant radiation therapy with concomitant chemotherapy. Part I. Are we able to predict tumor confined to the rectal wall?

To retrospectively assess accuracy of magnetic resonance (MR) imaging after radiation therapy with concomitant chemotherapy for downsizing of the primary lesion to ypT0-2 tumor confined to rectal wall in locally advanced rectal cancer, with histopathologic findings as reference standard, and to evaluate additional value of volumetric analysis. The institutional review board approved the study and waived informed consent. Sixty-seven patients met criteria of the study. T2-weighted MR images obtained before and after radiation therapy with concomitant chemotherapy were assessed for tumor stage by expert abdominal radiologist, colorectal surgeon, and general radiologist. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated; tumor volume was measured (compared with Mann-Whitney U test). Findings were correlated with histopathologic findings. Sixty-seven patients (38 men, 29 women; mean age, 63 years) who underwent radiation therapy with concomitant chemotherapy and surgery (all but one) were evaluated. The PPV for prediction of tumor confined to rectal wall (ypT0-2) was 91% (10 of 11), 86% (six of seven), and 88% (seven of eight) for expert abdominal radiologist, surgeon, and general radiologist, respectively. In 24 patients, sensitivity was 42% (10), 25% (six), and 29% (seven). ypT0-2 tumors had significantly smaller volumes than did ypT3-4 tumors before radiation therapy with concomitant chemotherapy (55 vs 92 cm(3), P = .038). Volume reduction rates were significantly higher in ypT0-2 than in ypT3-4 tumors (89% vs 61%, P < .001). If volume before radiation therapy with concomitant chemotherapy was 50 cm(3) or smaller and volume reduction rate was 75% or higher, excised tumor was always confined to rectal wall (ypT0-2). By using these criteria, 43% (six of 14) of cases with overstaging could have been predicted to be ypT0-2 tumors correctly. Downsizing to ypT0-2 tumors can be accurately predicted by combining morphologic tumor staging predictions with results from volumetric analyses. MR images obtained after radiation therapy with concomitant chemotherapy might be helpful in more individualized treatment planning.

Dresen RC ，Beets GL ，Rutten HJ ，Engelen SM ，Lahaye MJ ，Vliegen RF ，de Bruïne AP ，Kessels AG ，Lammering G ，Beets-Tan RG ... -  《-》

Locally advanced rectal cancer: MR imaging for restaging after neoadjuvant radiation therapy with concomitant chemotherapy. Part II. What are the criteria to predict involved lymph nodes?

To prospectively determine diagnostic performance of predictive criteria for nodal restaging after radiation therapy with concomitant chemotherapy by using ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance (MR) imaging in patients with rectal cancer. After institutional review board approval and informed consent were obtained, 39 patients (24 men, 15 women; mean age, 64 years) with rectal cancer underwent USPIO-enhanced two-dimensional (2D) T2-weighted fast spin-echo, three-dimensional (3D) T1-weighted gradient-echo, and 3D T2*-weighted MR for restaging. Two observers evaluated nodes for border irregularity, short- and long-axis diameters, and estimated percentage of white region (<30%, 30%-50%, or >50%) within the node (3D T2*-weighted images). Ratio of the measured surface area of the white region within the black node to the measured surface area of the total node (Ratio(A)) was calculated. Signal intensity (SI) in gluteus muscle (SI(GM)) and in total node (SI(TN)) were used to calculate SI(TN)/SI(GM) ratio. Histopathologic findings were reference standard. Receiver operating characteristic (ROC) curves were compared and interobserver agreement was determined. Lesion-by-lesion analysis was feasible in 201 lymph nodes. Area under the ROC curve (AUC) of border and short- and long-axis diameters for observer 1 were 0.85, 0.87, and 0.88 and for observer 2 were 0.70, 0.89, and 0.87, respectively. AUC for estimated percentage of white region within the node, Ratio(A), and SI(TN)/SI(GM) ratio for observer 1 were 0.98, 0.99, and 0.62 and for observer 2 were 0.97, 0.98, and 0.65, respectively. AUC for USPIO-enhanced MR criteria was significantly better than AUC for conventional MR criteria (P < .01). All criteria except border irregularity and SI(TN)/SI(GM) ratio showed high interobserver agreement (kappa > 0.79). The most reliable predictors for identifying benign nodes after radiation therapy with concomitant chemotherapy by using USPIO-enhanced MR imaging for restaging in patients with rectal cancer were estimated percentage of white region within the node and Ratio(A). Measurements on standard 2D T2-weighted fast spin-echo images versus primary staging results offer reasonably good accuracy to identify benign lymph nodes after therapy.

Lahaye MJ ，Beets GL ，Engelen SM ，Kessels AG ，de Bruïne AP ，Kwee HW ，van Engelshoven JM ，van de Velde CJ ，Beets-Tan RG ... -  《-》

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 ... -  《-》

Locally advanced rectal cancer: MR imaging in prediction of response after preoperative chemotherapy and radiation therapy.

To prospectively differentiate, at magnetic resonance (MR) imaging, patients with locally advanced nonmucinous rectal cancer who will respond to long-course chemotherapy and radiation therapy (CRT) from those who will not respond, with histopathologic results as the reference standard. Institutional review board approval for this study was obtained, and all patients provided written informed consent. High-spatial-resolution T2-weighted MR images were acquired before and 6-8 weeks after CRT in 53 patients (33 men, 20 women; mean age, 63 years; age range, 42-79 years). Patients were categorized as responders to CRT (patients with T3 cancer that converted to T2 or a lower stage, patients with T4 cancer that converted to T3 or a lower stage) or as nonresponders (patients with stable or progressive disease). At the posttreatment MR imaging examination, a decrease in signal intensity was considered to represent a morphologic response with fibrosis. Before CRT and surgery, tumor volume was calculated at MR imaging by multiplying cross-sectional area by section thickness. Tumor length was measured at MR imaging and in the histopathologic specimen. Nodal downstaging was evaluated. The relationship between pathologic response, morphologic MR imaging response, and percentage volume reduction was evaluated with the Mann-Whitney-Wilcoxon two-sample test. Morphologic response assessment with MR imaging achieved a positive predictive value (PPV) of 84.2% (32 of 38) and a negative predictive value (NPV) of 66.7% (10 of 15). Volume reduction extent (> or = 70%) was significantly different between patients in whom disease was downstaged and those in whom it was not downstaged (P = .000005) and showed additional diagnostic value, with an overall accuracy of 86.8% (46 of 53). Presurgical MR imaging and histopathologic tumor length did not show a significant difference. MR imaging accuracy for lymph node (N) stage was 86.8% (46 of 53) on the basis of morphologic criteria. After CRT, morphologic and volumetric evaluation at MR imaging had a high PPV and a low NPV for response assessment. The detection of small clusters of residual tumor cells within fibrosis remains a problem. http://radiology.rsnajnls.org/cgi/content/full/250/3/730/DC1.

Barbaro B ，Fiorucci C ，Tebala C ，Valentini V ，Gambacorta MA ，Vecchio FM ，Rizzo G ，Coco C ，Crucitti A ，Ratto C ，Bonomo L ... -  《-》

Rectal cancer: MR imaging before neoadjuvant chemotherapy and radiation therapy for prediction of tumor-free circumferential resection margins and long-term survival.

To retrospectively evaluate the prognostic importance of involvement of the circumferential resection margin predicted by using magnetic resonance (MR) imaging before neoadjuvant treatment in patients with rectal cancer. The local institutional review board approved the retrospective analysis of the data and waived informed consent. Sixty-eight patients (52 men, 16 women; mean age +/- standard deviation, 58.9 years +/- 9.4) with cT3 NX M0 tumors were included. T2-weighted MR images were analyzed in consensus by two radiologists with respect to the shortest distance between the outermost parts of the tumor to the adjacent mesorectal fascia (as the potential circumferential resection margin in total mesorectal excision). Histopathologic and follow-up data were available for all patients (mean follow-up time, 54 months; range, 31-77 months). To compare local recurrence and survival rates, the population was divided into three groups categorized according to the minimum distance of the tumor to the mesorectal fascia (group 1, <or=1 mm; group 2, >1 to 5 mm; group 3, >5 mm). Univariate Cox and multivariate proportional hazard regression models were used to test the prognostic importance of clinical, histopathologic regression, and histopathologic tumor parameters. MR imaging led to accurate prediction of a histologically involved circumferential resection margin (sensitivity, 100%; specificity, 88%). The rates for local recurrence (group 1, 33%; group 2, 5%; group 3, 6%; P<.02) and 5-year overall survival (group 1, 39%; group 2, 70%; group 3, 90%; P<.001) differed significantly among the predefined groups. The distance to the mesorectal fascia was an independent prognostic parameter in multivariate analysis (P<.001), and histopathologic response to treatment provided no additional information. Prediction of the tumor-free circumferential resection margin assessed with MR imaging before initiation of neoadjuvant chemotherapy and radiation therapy proved to be a prognostic factor in rectal cancer.

Wieder HA ，Rosenberg R ，Lordick F ，Geinitz H ，Beer A ，Becker K ，Woertler K ，Dobritz M ，Siewert JR ，Rummeny EJ ，Stollfuss JC ... -  《-》