MRI In Rectal Cancer Research Articles

MRI rectal cancer in Australia and New Zealand: An audit from the PETACC-6 trial.

An MRI audit substudy was conducted in patients who underwent an MRI prior to treatment in Australia and New Zealand as part of the PETACC-6 trial in locally advanced rectal cancer. A total of 82 patients from 15 centres had rectal MRI scans reviewed for technique, data included in reports and comparison of reports with blinded central reporting by two experienced radiologists. In total, 82% performed minimum T2 sagittal and T2 axial oblique sequences. The high-resolution T2 sequence parameters varied significantly with only 33% obtaining a voxel size of <1.3mm3 . The rate of inclusion of relevant findings in the reports was T3 distance in mm 21%, N stage 84%, circumferential resection margin (CRM) status 72%, extramural venous invasion (EMVI) status 29% and distance from the puborectalis sling 17%. In total, 31% reports included all of T stage with T3 substage, N stage and CRM involvement. In total, 17% reports included these 3 findings and EMVI. Eleven reports used a template with 82% of these including the first 3 findings. The agreement with central reporters was T stage 76%, N stage 70%, CRM status 57% and EMVI 16%. There is significant variation in scan quality and low rates of including all relevant findings in rectal MRI reports in the audit. The authors recommend adoption of routine sequences and template reports in both trial settings and routine practice to improve scan technique and adequacy of reports in rectal cancer MRI staging scans across Australia and New Zealand.

MRI In rectal cancer: Correlations between MRI features and molecular markers Ki‐67, HIF‐1α, and VEGF

To investigate whether the apparent diffusion coefficient (ADC) values acquired from diffusion-weighted magnetic resonance imaging (DW-MRI) are correlated with molecular markers Ki-67, hypoxia-inducible factor 1α (HIF-1α), and vascular endothelial growth factor (VEGF) in rectal cancer (RC). Ninety-one patients (64 males and 27 females) diagnosed with rectal cancer underwent 3.0T DW-MRI before any anticancer treatment. DW-MRI was performed using the single-shot echo-planar imaging technique (b = 0 and b = 800 s/mm(2) ). The patients underwent surgery within 1 week after MRI. Ki-67, HIF-1α, and VEGF expression were assessed by immunohistochemistry at both the resected margins and the center of the tumor. We noted that ADC values correlated positively with histology differentiations (r = 0.336, P = 0.001) and negatively with carcinoembryonic antigen level (r = -0.217, P = 0.039) in RC. Both the value and the level of Ki-67 expression were correlated inversely with the ADC values (r = -0.475, P < 0.001 and r = -0.555, P < 0.001). There was a weak negative correlation between HIF-1α expression and the ADC values (r = -0.304, P = 0.003). VEGF expression was correlated inversely with the ADC values of the RCs (r = -0.290, P = 0.005). However, no significant correlation was observed between VEGF expression and the ADC values in pT4 RCs (r = -0.166, P = 0.255). Our results suggest that the ADC values on DW-MRI may be used as a measurement of cell proliferation and hypoxia in RC. J. Magn. Reson. Imaging 2016;44:594-600.

707 Follow-up with MRI of rectal cancer treated by TEM: Recurrence detection and inter-observer reproducibility

707 Follow-up with MRI of rectal cancer treated by TEM: Recurrence detection and inter-observer reproducibility

MRI of Rectal Cancer: An Overview and Update on Recent Advances.

MRI is the modality of choice for rectal cancer staging. The high soft-tissue contrast of MRI accurately assesses the extramural tumor spread and relation to mesorectal fascia and the sphincter complex. This article reviews the role of MRI in the staging and treatment of rectal cancer. The relevant anatomy, MRI techniques, preoperative staging, post-chemoradiation therapy (CRT) imaging, and tumor recurrence are discussed with special attention to recent advances in knowledge. MRI is the modality of choice for staging rectal cancer to assist surgeons in obtaining negative surgical margins. MRI facilitates the accurate assessment of mesorectal fascia and the sphincter complex for surgical planning. Multiparametric MRI may also help in the prediction and estimation of response to treatment and in the detection of recurrent disease.

PO-0953: Quantitative diffusion-weighted MRI of rectal cancer is strongly influenced by the choice of b-values

PO-0953: Quantitative diffusion-weighted MRI of rectal cancer is strongly influenced by the choice of b-values

Value of gadofosveset-enhanced MRI and multiplanar reformatting for selecting good responders after chemoradiation for rectal cancer.

Our primary objective was to evaluate diagnostic performance of gadofosveset T1-weighted magnetic resonance imaging (T1W MRI) for discriminating between ypT0-2 and ypT3-4 tumours after chemoradiation therapy (CRT) for rectal cancer compared with T2W MRI for a general and expert reader. Second objectives included assessing the value of multiplanar reformatting (MPR) and interobserver agreement. A general and expert reader evaluated 49 patients for likelihood of ypT0-2 tumour after CRT on T2W, gadofosveset T1W MRI, and gadofosveset T1W MRI + T2W MRI. The general reader scored with and without MPR. Confidence level scores were used to construct receiver-operating characteristic (ROC) curves. Area under the curve (AUC) values and diagnostic parameters were calculated and compared. Gadofosveset T1W MRI + T2W MRI showed slightly superior sensitivity than T2W MRI for the general but not the expert reader. Specificity was higher for the expert on gadofosveset T1W MRI only compared with T2W MRI only (100% vs. 82%). MPR did not increase diagnostic performance. Interobserver agreement was highest for the combination of gadofosveset-enhanced T1W imaging plus T2W MRI. The sole use or addition of gadofosveset-enhanced T1W MRI to T2W MRI did not increase significantly diagnostic performance for assessing ypT0-2 tumours. Adding gadofosveset-enhanced T1W MRI slightly increased sensitivity for the general reader and specificity for the expert reader, but this increase was not significant for more accurate clinical decision making. MPR did not improve diagnostic performance. • ycT restaging with MRI in rectal cancer is challenging. • Gadofosveset-enhanced T1W MRI has shown promise for nodal restaging. • Gadofosveset-enhanced T1W MRI did not significantly increase diagnostic performance for assessing ypT0-2-tumours. • Addition of the gadofosveset sequence to T2W MRI slightly increased sensitivity for the general reader. • MPR did not improve diagnostic performance of ycT staging.

Multiparametric MRI of rectal cancer in the assessment of response to therapy: a systematic review.

Conventional MRI is limited in the assessment of nodal status and T status after neoadjuvant chemoradiotherapy. Multiparametric MRI strives to overcome these issues by directly measuring the local microcirculation and cellular environment, thus possibly allowing for a more reliable evaluation of response to therapy. We assessed the available literature for the value of multiparametric MRI sequences (diffusion-weighted and dynamic contrast-enhanced imaging) in determining the response to neoadjuvant chemoradiotherapy in patients with rectal cancer. We conducted a systematic literature research in the PubMed database. English-language publications of the years 2000-2013 that applied multiparametric MRI in the neoadjuvant setting were included in this study. Patients received neoadjuvant chemoradiotherapy and MRI examinations for staging and assessment of response. Accuracy, specificity, and sensitivity of MRI in prediction/assessment of response to therapy were the included measures. Forty-three studies were included in this review; 30 of them included diffusion-weighted imaging sequences, and 13 included dynamic contrast-enhanced MRI. Conventional MRI is limited in the accuracy of both T and N stages and response assessment. Diffusion-weighted imaging and dynamic contrast-enhanced MRIs showed additional value in both the prediction and detection of (complete) response to therapy compared with conventional sequences alone, as well as in correct N staging along with new experimental contrast agents. The lack of standardization represents an important technical limitation. Most studies are conducted in an experimental setting; therefore, larger multicenter prospective studies are needed to verify the present findings. Advanced, functional MRI techniques allow for the quantification of tumor biological processes, such as microcirculation, vascular permeability, and tissue cellularity. This new technology has begun to show potential advantages over standard morphologic imaging in the restaging of rectal cancer, allowing for more accurate prognostication of response and potentially introducing an era allowing earlier treatment alteration and more accurate noninvasive surveillance, which could improve patient outcomes.

Multi-parametric MRI of rectal cancer – Do quantitative functional MR measurements correlate with radiologic and pathologic tumor stages?

PurposeThe purpose of this study is two-fold. First, to evaluate, whether functional rectal MRI techniques can be analyzed in a reproducible manner by different readers and second, to assess whether different clinical and pathologic T and N stages can be differentiated by functional MRI measurements. Materials and methods54 patients (38 men, 16 female; mean age 63.2±12.2 years) with pathologically proven rectal cancer were included in this retrospective IRB-approved study. All patients were referred for a multi-parametric MRI protocol on a 3 Tesla MR-system, consisting of a high-resolution, axial T2 TSE sequence, DWI and perfusion imaging (plasma flow –s PFTumor) prior to any treatment. Two experienced radiologists evaluated the MRI measurements, blinded to clinical data and outcome. Inter-reader correlation and the association of functional MRI parameters with c- and p-staging were analyzed. ResultsThe inter-reader correlation for lymph node (ρ 0.76–0.94; p<0.0002) and primary tumor (ρ 0.78–0.92; p<0.0001) apparent diffusion coefficient and plasma flow (PF) values was good to very good. PFTumor values decreased with cT stage with significant differences identified between cT2 and cT3 tumors (229 versus 107.6ml/100ml/min; p=0.05). ADCTumor values did not differ significantly. No substantial discrepancies in lymph node ADCLn values or short axis diameter were found among cN1-3 stages, whereas PFLn values were distinct between cN1 versus cN2 stages (p=0.03). In the patients without neoadjuvant RCT no statistically significant differences in the assessed functional parameters on the basis of pathologic stage were found. ConclusionThis study illustrates that ADC as well as MR perfusion values can be analyzed with good interobserver agreement in patients with rectal cancer. Moreover, MR perfusion parameters may allow accurate differentiation of tumor stages. Both findings suggest that functional MRI parameters may help to discriminate T and N stages for clinical decision making.

A computer-aided algorithm to quantitatively predict lymph node status on MRI in rectal cancer

The aim of this study was to demonstrate the principle of supporting radiologists by using a computer algorithm to quantitatively analyse MRI morphological features used by radiologists to predict the presence or absence of metastatic disease in local lymph nodes in rectal cancer. A computer algorithm was developed to extract and quantify the following morphological features from MR images: chemical shift artefact; relative mean signal intensity; signal heterogeneity; and nodal size (volume or maximum diameter). Computed predictions on nodal involvement were generated using quantified features in isolation or in combinations. Accuracies of the predictions were assessed against a set of 43 lymph nodes, determined by radiologists as benign (20 nodes) or malignant (23 nodes). Predictions using combinations of quantified features were more accurate than predictions using individual features (0.67-0.86 vs 0.58-0.77, respectively). The algorithm was more accurate when three-dimensional images were used (0.58-0.86) than when only middle image slices (two-dimensional) were used (0.47-0.72). Maximum node diameter was more accurate than node volume in representing the nodal size feature; combinations including maximum node diameter gave accuracies up to 0.91. We have developed a computer algorithm that can support radiologists by quantitatively analysing morphological features of lymph nodes on MRI in the context of rectal cancer nodal staging. We have shown that this algorithm can combine these quantitative indices to generate computed predictions of nodal status which closely match radiological assessment. This study provides support for the feasibility of computer-assisted reading in nodal staging, but requires further refinement and validation with larger data sets.

Perfusion MRI for the prediction of treatment response after preoperative chemoradiotherapy in locally advanced rectal cancer

To evaluate the utility of perfusion MRI as a potential biomarker for predicting response to chemoradiotherapy (CRT) in locally advanced rectal cancer. Thirty-nine patients with primary rectal carcinoma who were scheduled for preoperative CRT were prospectively recruited. Perfusion MRI was performed with a 3.0-T MRI system in all patients before therapy, at the end of the 2nd week of therapy, and before surgery. The K (trans) (volume transfer constant) and V (e) (extracellular extravascular space fraction) were calculated. Before CRT, the mean tumour K (trans) in the downstaged group was significantly higher than that in the non-downstaged group (P = 0.0178), but there was no significant difference between tumour regression grade (TRG) responders and TRG non-responders (P = 0.1392). Repeated-measures analysis of variance (ANOVA) showed significant differences for evolution of K (trans) values both between downstaged and non-downstaged groups (P = 0.0215) and between TRG responders and TRG non-responders (P = 0.0001). Regarding V (e), no significant differences were observed both between downstaged and non-downstaged groups (P = 0.689) or between TRG responders and TRG non-responders (P = 0.887). Perfusion MRI of rectal cancer can be useful for assessing tumoural K (trans) changes by CRT. Tumours with high pre-CRT K (trans) values tended to respond favourably to CRT, particularly in terms of downstaging criteria. • Perfusion MRI can now assess therapeutic response of tumours to therapy. • Tumours with high initial K ( trans ) values responded favourably to chemoradiotherapy. • Perfusion MRI of rectal cancer may help with decisions about management.

Diffusion‐weighted MRI in rectal cancer: Apparent diffusion coefficient as a potential noninvasive marker of tumor aggressiveness

To assess the value of diffusion-weighted MR imaging (DWI) as a potential noninvasive marker of tumor aggressiveness in rectal cancer, by analyzing the relationship between tumoral apparent diffusion coefficient (ADC) values and MRI and histological prognostic parameters. Fifty rectal cancer patients underwent primary staging MRI including DWI before surgery and neo-adjuvant therapy. In 47, surgery was preceded by short-course radiation therapy (n = 28) or long-course chemoradiation therapy (n = 19). Mean tumor ADC was measured and compared between subgroups based on pretreatment CEA levels, MRI parameters (mesorectal fascia - MRF - status; T-stage; N-stage) and histological parameters (differentiation grade: poorly differentiated, poorly moderately differentiated, moderately differentiated, moderately well differentiated, well-differentiated; lymphangiovascular invasion). Mean tumor ADCs differ between MRF-free versus MRF-invaded tumors (P = 0.013), the groups of cN0 versus cN+ cancers (P = 0.011), and between the several groups of histological differentiation grades (P = 0.025). There was no significant difference in mean ADCs between the various groups of CEA levels, the T stage, and the presence of lymphangiovascular invasion. Lower ADC values were associated with a more aggressive tumor profile. Significant correlations were found between mean ADC values and radiological MRF status, N stage and differentiation grade. ADC has the potential to become an imaging biomarker of tumor aggressiveness profile.

Postgraduate Multidisciplinary Development Program: Impact on the Interpretation of Pelvic MRI in Patients With Rectal Cancer: A Clinical Audit in West Denmark

Pelvic MRI in patients with rectal cancer is an accepted tool for the identification of patients with poor prognostic tumors who may benefit from neoadjuvant therapy. In Denmark, this examination has been mandatory in the workup on rectal cancer since 2002. This study aimed to assess the impact of a multidisciplinary team course for doctors in West Denmark on the technical quality, reporting, and interpretation of pelvic MRI in rectal cancer. This study is interventional and observational. Two expert reviewers served as reference standard in the evaluation of consecutively performed pelvic MRI scans against which the evaluations from the participating centers were compared. Five imaging centers in West Denmark performed pelvic MRI in rectal cancer from March 1 to December 31, 2007. One hundred and eighty patients with newly diagnosed rectal cancer were enrolled. This study involved a multidisciplinary team course including on-site visits. The MR scans were evaluated concerning technical performance, reporting, interpretation, and the ability to correctly allocate patients to chemoirradiation based on imaging findings pre- and postcourse. Eighteen percent of the scans were of satisfying technical quality for staging rectal cancer before the course compared with 74% after (P < .001). After the course, the T-stage subclassification, the depth of extramural spread, the N stage, and the presence of extramural vascular invasion was reported significantly more frequently. Based on imaging findings, we observed no significant effect on the ability to perform correct treatment stratification according to Danish guidelines. The evaluation process itself may have improved the performance of the participating centers. Performance and reporting of pelvic MRI in patients with rectal cancer can be improved significantly through multidisciplinary development courses and on-site visits, whereas improvements in image interpretation with regard to treatment stratification may demand more intensive efforts.

MRI After Chemoradiotherapy of Rectal Cancer: A Useful Tool to Select Patients for Local Excision

If identification of good responders to neoadjuvant chemoradiotherapy in rectal cancer is possible, there might be opportunities for local excision in selected patients. The aim of this study was to determine whether postchemoradiation MRI in rectal cancer can accurately identify ypT0 to 2/ypN0, because both features are essential for identification of good responders. Seventy-nine patients (4 hospitals) underwent postchemoradiation MRI, 62 received a lymph node-specific contrast agent (ultrasmall superparamagnetic iron oxide). An expert and general radiologist prospectively predicted whether the tumor penetrated the mesorectal fat and whether nodes were sterilized after chemoradiation. Histology was the reference standard. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. For prediction of whether a tumor penetrated the bowel wall, there was an negative predictive value of 0.90 and 0.76 for the expert and general radiologist, respectively. The negative predictive value for prediction of nodal status was 0.95 and 0.85 for expert and general radiologist, respectively. This prospective multicenter study demonstrates that MRI with a lymph node-specific contrast agent interpreted by an expert radiologist can select ypT0 to 2/ypN0 rectal cancer with low risk of undetected nodal metastases or invasion through the bowel wall. These patients could thus have been selected for local excision. However, future studies will have to prove equal outcome of such a modified surgical approach compared with current practice.

MRI of rectal cancer: which technical choices for which therapeutic objectives?

MRI of rectal cancer: which technical choices for which therapeutic objectives?

The importance of rectal cancer MRI protocols on iInterpretation accuracy

BackgroundMagnetic resonance imaging (MRI) is used for preoperative local staging in patients with rectal cancer. Our aim was to retrospectively study the effects of the imaging protocol on the staging accuracy.Patients and methodsMR-examinations of 37 patients with locally advanced disease were divided into two groups; compliant and noncompliant, based on the imaging protocol, without knowledge of the histopathological results. A compliant rectal cancer imaging protocol was defined as including T2-weighted imaging in the sagittal and axial planes with supplementary coronal in low rectal tumors, alongside a high-resolution plane perpendicular to the rectum at the level of the primary tumor. Protocols not complying with these criteria were defined as noncompliant. Histopathological results were used as gold standard.ResultsCompliant rectal imaging protocols showed significantly better correlation with histopathological results regarding assessment of anterior organ involvement (sensitivity and specificity rates in compliant group were 86% and 94%, respectively vs. 50% and 33% in the noncompliant group). Compliant imaging protocols also used statistically significantly smaller voxel sizes and fewer number of MR sequences than the noncompliant protocolsConclusionAppropriate MR imaging protocols enable more accurate local staging of locally advanced rectal tumors with less number of sequences and without intravenous gadolinium contrast agents.

Preoperative MRI of rectal cancer with and without rectal water filling: an intraindividual comparison.

The purpose of our study was to determine if a rectal distention using warm water may improve the accuracy of MRI for the preoperative staging of rectal carcinoma. SUBJECTS AND METHODS. Sixty-two patients with surgically proven rectal carcinomas underwent pelvic MRI before and after a rectal distention by warm water. Four radiologists, who were blinded to the study, reviewed each set of T1- and T2-weighted axial images obtained before and after the rectal distention and scored the image of the tumor. The accuracies for determining the tumor penetration of the outer wall of the rectum and the regional lymph node involvement were compared by analyzing the area under the receiver operating characteristic curve (A(z)). For all reviewers, the tumor depiction scores were significantly higher in the distended images (3.8-3.9 for reviewers 1-4) than in the nondistended images (3.0-3.2) (p < 0.01). For determining the outer wall penetration, the accuracy of the three reviewers was significantly higher with the rectal distention images than with the nondistended images (p < 0.05). The mean accuracy of the all reviewers was significantly better with the distended images (A(z) = 0.922) than with the nondistended images (A(z) = 0.841) (p < 0.05). For determining the presence of regional lymph node involvement, all the reviewers came to similar conclusions in analyzing the two image sets. Rectal distention by water filling may improve the depiction of a primary rectal tumor and the assessment accuracy of a perirectal tumor extension, but it does not improve the accuracy for determining the presence of regional lymph node involvement.

MRI in rectal cancer: the T stage and circumferential resection margin.

Different stages of rectal cancer show differing degrees of risk for local recurrence. Paramount for the selection and differentiated treatment of the different risk groups is a reliable preoperative test that can distinguish between these subgroups. There is recent evidence suggesting that MRI can serve for this purpose, because it accurately predicts the circumferential resection margin. In this article the role of MRI in the preoperative management of rectal cancer patients will be discussed.