Development and multicenter validation of a multiparametric imaging model to predict treatment response in rectal cancer

OBJECTIVES

To develop and validate a multiparametric model to predict neoadjuvant treatment response in rectal cancer at baseline using a heterogeneous multicenter MRI dataset.

METHODS

Baseline staging MRIs (T2W (T2-weighted)-MRI, diffusion-weighted imaging (DWI) / apparent diffusion coefficient (ADC)) of 509 patients (9 centres) treated with neoadjuvant chemoradiotherapy (CRT) were collected. Response was defined as (1) complete versus incomplete response, or (2) good (Mandard tumor regression grade (TRG) 1-2) versus poor response (TRG3-5). Prediction models were developed using combinations of the following variable groups: (1) Non-imaging: age/sex/tumor-location/tumor-morphology/CRT-surgery interval (2) Basic staging: cT-stage/cN-stage/mesorectal fascia involvement, derived from (2a) original staging reports, or (2b) expert re-evaluation (3) Advanced staging: variables from 2b combined with cTN-substaging/invasion depth/extramural vascular invasion/tumor length (4) Quantitative imaging: tumour volume + first-order histogram features (from T2W-MRI and DWI/ADC) Models were developed with data from 6 centers (n = 412) using logistic regression with the Least Absolute Shrinkage and Selector Operator (LASSO) feature selection, internally validated using repeated (n = 100) random hold-out validation, and externally validated using data from 3 centers (n = 97).

RESULTS

After external validation, the best model (including non-imaging and advanced staging variables) achieved an area under the curve of 0.60 (95%CI=0.48-0.72) to predict complete response and 0.65 (95%CI=0.53-0.76) to predict a good response. Quantitative variables did not improve model performance. Basic staging variables consistently achieved lower performance compared to advanced staging variables.

CONCLUSIONS

Overall model performance was moderate. Best results were obtained using advanced staging variables, highlighting the importance of good-quality staging according to current guidelines. Quantitative imaging features had no added value (in this heterogeneous dataset).

CLINICAL RELEVANCE STATEMENT

Predicting tumour response at baseline could aid in tailoring neoadjuvant therapies for rectal cancer. This study shows that image-based prediction models are promising, though are negatively affected by variations in staging quality and MRI acquisition, urging the need for harmonization.

KEY POINTS

This multicenter study combining clinical information and features derived from MRI rendered disappointing performance to predict response to neoadjuvant treatment in rectal cancer. Best results were obtained with the combination of clinical baseline information and state-of-the-art image-based staging variables, highlighting the importance of good quality staging according to current guidelines and staging templates. No added value was found for quantitative imaging features in this multicenter retrospective study. This is likely related to acquisition variations, which is a major problem for feature reproducibility and thus model generalizability.

Evaluation of National Surgical Practice for Lateral Lymph Nodes in Rectal Cancer in an Untrained Setting

BACKGROUND

Involved lateral lymph nodes (LLNs) have been associated with increased local recurrence (LR) and ipsi-lateral LR (LLR) rates. However, consensus regarding the indication and type of surgical treatment for suspicious LLNs is lacking. This study evaluated the surgical treatment of LLNs in an untrained setting at a national level.

METHODS

Patients who underwent additional LLN surgery were selected from a national cross-sectional cohort study regarding patients undergoing rectal cancer surgery in 69 Dutch hospitals in 2016. LLN surgery consisted of either 'node-picking' (the removal of an individual LLN) or 'partial regional node dissection' (PRND; an incomplete resection of the LLN area). For all patients with primarily enlarged (≥7 mm) LLNs, those undergoing rectal surgery with an additional LLN procedure were compared to those  undergoing only rectal resection.

RESULTS

Out of 3057 patients, 64 underwent additional LLN surgery, with 4-year LR and LLR rates of 26% and 15%, respectively. Forty-eight patients (75%) had enlarged LLNs, with corresponding recurrence rates of 26% and 19%, respectively. Node-picking (n = 40) resulted in a 20% 4-year LLR, and a 14% LLR after PRND (n = 8; p = 0.677). Multivariable analysis of 158 patients with enlarged LLNs undergoing additional LLN surgery (n = 48) or rectal resection alone (n = 110) showed no significant association of LLN surgery with 4-year LR or LLR, but suggested higher recurrence risks after LLN surgery (LR: hazard ratio [HR] 1.5, 95% confidence interval [CI] 0.7-3.2, p = 0.264; LLR: HR 1.9, 95% CI 0.2-2.5, p = 0.874).

CONCLUSION

Evaluation of Dutch practice in 2016 revealed that approximately one-third of patients with primarily enlarged LLNs underwent surgical treatment, mostly consisting of node-picking. Recurrence rates were not significantly affected by LLN surgery, but did suggest worse outcomes. Outcomes of LLN surgery after adequate training requires further research.

Hiatal hernia recurrences after laparoscopic surgery: exploring the optimal technique

INTRODUCTION

The recurrence rate of hiatal hernia (HH) after laparoscopic surgery with crural repair and Nissen or Toupet fundoplication is high (< 25-42%). HH repair can be reinforced with additional anterior sutures, vertical mesh strips (VMS) or mesh placement but the effect in the long-term (> 1 year) is still unclear. We determined the recurrence rate of HH after surgery and established whether the use of reinforcement techniques could reduce long-term recurrence rates.

METHODS

In this retrospective cohort study patients were included if they underwent a laparoscopic fundoplication in this hospital between 2012 and 2019. HH was measured with computed tomography and baseline patient characteristics and surgical details were collected. Primary outcomes were recurrence of symptoms and re-intervention, secondary outcome was effect of surgical reinforcement techniques. Statistical analyses comprised chi-square tests, Mann-Whitney U tests and uni- and multivariable logistic regression analyses.

RESULTS

In total, 307 patients were included, 206 women and 101 men. During primary surgery, 208 patients underwent a Toupet fundoplication and 97 patients underwent a Nissen fundoplication. Reinforcements consisted of anterior sutures in 132 patients, VMS in 89 patients and mesh in 17 patients. After primary surgery, recurrence of HH was diagnostically confirmed in 64 patients (20.8%). Use of VMS during primary surgery was significantly associated with fewer recurrences (OR = 0.34, p = 0.048), corrected for confounding factors. Secondary surgery was performed in 54 patients (17.6%) and tertiary surgery in five patients (1.6%). Mesh and VMS were used more during secondary and tertiary surgery.

CONCLUSION

The recurrence rate among HH patients in this cohort study was 20.8% with a mean follow-up time of 6 years. Secondary surgery was performed in 17.6% of the patients. In future, the use of VMS might lead to fewer recurrences after primary laparoscopic repair of HH.

OC-067 HIATAL HERNIA RECURRENCES AFTER LAPAROSCOPIC SURGERY: EXPLORING CONTRIBUTING SURGICAL FACTORS

Aim

The recurrence rate of hiatus hernia (HH) is high after laparascopic surgery (25–42%). HH repair can be reinforced by means of additional ventral sutures, pledgets or mesh placement. We determined the recurrence rate of HH after surgery and established whether lower long-term recurrence rates can be achieved with reinforcement techniques.

Methods

Patients were included in this retrospective cohort study if they underwent a laparoscopic fundoplication in our hospital between 2012–2019. HH was measured on CT scans and patient files were reviewed.

Results

In total, 307 patients were included, 206 women and 101 men. Pre-operatively, 102 patients were diagnosed with type III HH and 68 patients with type IV HH. The median transverse diameter of the HH was 3.2 cm. 208 patients underwent a Toupet fundoplication and 97 patients underwent a Nissen fundoplication. Reinforcements consisted of ventral sutures in 132 patients, pledgets in 89 patients and mesh in 17 patients. After primary surgery, recurrence of HH was diagnostically confirmed in 64 patients (20.8%). Secondary surgery was performed in 54 patients (17.6%) and tertiary surgery in 5 patients (1.6%). Use of pledgets during primary surgery (OR=0.34, p=0.048) was significantly associated with fewer recurrences, corrected for confounding factors. Use of ventral sutures and mesh were not significantly associated with reduced recurrence rates.

Conclusions

The recurrence rate among HH patients in our hospital was 20.8% with a mean follow-up time of 6 years. In future, the use of pledgets might lead to fewer recurrences after primary laparoscopic repair of HH.

Sources of variation in multicenter rectal MRI data and their effect on radiomics feature reproducibility

OBJECTIVES

To investigate sources of variation in a multicenter rectal cancer MRI dataset focusing on hardware and image acquisition, segmentation methodology, and radiomics feature extraction software.

METHODS

T2W and DWI/ADC MRIs from 649 rectal cancer patients were retrospectively acquired in 9 centers. Fifty-two imaging features (14 first-order/6 shape/32 higher-order) were extracted from each scan using whole-volume (expert/non-expert) and single-slice segmentations using two different software packages (PyRadiomics/CapTk). Influence of hardware, acquisition, and patient-intrinsic factors (age/gender/cTN-stage) on ADC was assessed using linear regression. Feature reproducibility was assessed between segmentation methods and software packages using the intraclass correlation coefficient.

RESULTS

Image features differed significantly (p < 0.001) between centers with more substantial variations in ADC compared to T2W-MRI. In total, 64.3% of the variation in mean ADC was explained by differences in hardware and acquisition, compared to 0.4% by patient-intrinsic factors. Feature reproducibility between expert and non-expert segmentations was good to excellent (median ICC 0.89-0.90). Reproducibility for single-slice versus whole-volume segmentations was substantially poorer (median ICC 0.40-0.58). Between software packages, reproducibility was good to excellent (median ICC 0.99) for most features (first-order/shape/GLCM/GLRLM) but poor for higher-order (GLSZM/NGTDM) features (median ICC 0.00-0.41).

CONCLUSIONS

Significant variations are present in multicenter MRI data, particularly related to differences in hardware and acquisition, which will likely negatively influence subsequent analysis if not corrected for. Segmentation variations had a minor impact when using whole volume segmentations. Between software packages, higher-order features were less reproducible and caution is warranted when implementing these in prediction models.

KEY POINTS

• Features derived from T2W-MRI and in particular ADC differ significantly between centers when performing multicenter data analysis. • Variations in ADC are mainly (> 60%) caused by hardware and image acquisition differences and less so (< 1%) by patient- or tumor-intrinsic variations. • Features derived using different image segmentations (expert/non-expert) were reproducible, provided that whole-volume segmentations were used. When using different feature extraction software packages with similar settings, higher-order features were less reproducible.

Evolutions in rectal cancer MRI staging and risk stratification in The Netherlands

Purpose

To analyze how the MRI reporting of rectal cancer has evolved (following guideline updates) in The Netherlands.

Methods

Retrospective analysis of 712 patients (2011–2018) from 8 teaching hospitals in The Netherlands with available original radiological staging reports that were re-evaluated by a dedicated MR expert using updated guideline criteria. Original reports were classified as “free-text,” “semi-structured,” or “template” and completeness of reporting was documented. Patients were categorized as low versus high risk, first based on the original reports (high risk = cT3-4, cN+, and/or cMRF+) and then based on the expert re-evaluations (high risk = cT3cd-4, cN+, MRF+, and/or EMVI+). Evolutions over time were studied by splitting the inclusion period in 3 equal time periods.

Results

A significant increase in template reporting was observed (from 1.6 to 17.6–29.6%; p < 0.001), along with a significant increase in the reporting of cT-substage, number of N+ and extramesorectal nodes, MRF invasion and tumor-MRF distance, EMVI, anal sphincter involvement, and tumor morphology and circumference. Expert re-evaluation changed the risk classification from high to low risk in 18.0% of cases and from low to high risk in 1.7% (total 19.7%). In the majority (17.9%) of these cases, the changed risk classification was likely (at least in part) related to use of updated guideline criteria, which mainly led to a reduction in high-risk cT-stage and nodal downstaging.

Conclusion

Updated concepts of risk stratification have increasingly been adopted, accompanied by an increase in template reporting and improved completeness of reporting. Use of updated guideline criteria resulted in considerable downstaging (of mainly high-risk cT-stage and nodal stage).

Graphic abstract

Comparison of translabial three-dimensional ultrasound with magnetic resonance imaging for measurement of levator hiatal biometry at rest

OBJECTIVES

To compare translabial three-dimensional (3D) ultrasound with magnetic resonance imaging (MRI) for the measurement of levator hiatal biometry at rest in women with pelvic organ prolapse, and to determine the interobserver reliability between two independent observers for ultrasound and MRI measurements.

METHODS

Data were derived from a multicenter prospective cohort study in which women scheduled for conventional anterior colporrhaphy underwent translabial 3D ultrasound and MRI prior to surgery. Intraclass correlation coefficients (ICCs) were calculated to estimate interobserver reliability between two independent observers and determine the agreement between ultrasound and MRI measurements. Bland-Altman plots were created to assess the agreement between ultrasound and MRI measurements.

RESULTS

Data from 139 women from nine hospitals were included in the study. The interobserver reliability of ultrasound assessment at rest, during Valsalva maneuver and during contraction and of MRI assessment at rest were moderate or good. The agreement between ultrasound and MRI for the measurement of levator hiatal biometry at rest was moderate, with ICCs of 0.52 (95%CI, 0.32-0.66) for levator hiatal area, 0.44 (95%CI, 0.21-0.60) for anteroposterior diameter and 0.44 (95%CI, 0.22-0.60) for transverse diameter. Levator hiatal biometry measurements were statistically significantly larger on MRI than on translabial 3D ultrasound.

CONCLUSIONS

The agreement between translabial 3D ultrasound and MRI for measurement of the levator hiatus at rest in women with pelvic organ prolapse was only moderate. The results of translabial 3D ultrasound and MRI should therefore not be used interchangeably in daily practice or in clinical research. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Automated and Semiautomated Segmentation of Rectal Tumor Volumes on Diffusion-Weighted MRI: Can It Replace Manual Volumetry?

PURPOSE

Diffusion-weighted imaging (DWI) tumor volumetry is promising for rectal cancer response assessment, but an important drawback is that manual per-slice tumor delineation can be highly time consuming. This study investigated whether manual DWI-volumetry can be reproduced using a (semi)automated segmentation approach.

METHODS AND MATERIALS

Seventy-nine patients underwent magnetic resonance imaging (MRI) that included DWI (highest b value [b1000 or b1100]) before and after chemoradiation therapy (CRT). Tumor volumes were assessed on b1000 (or b1100) DWI before and after CRT by means of (1) automated segmentation (by 2 inexperienced readers), (2) semiautomated segmentation (manual adjustment of the volumes obtained by method 1 by 2 radiologists), and (3) manual segmentation (by 2 radiologists); this last assessment served as the reference standard. Intraclass correlation coefficients (ICC) and Dice similarity indices (DSI) were calculated to evaluate agreement between different methods and observers. Measurement times (from a radiologist's perspective) were recorded for each method.

RESULTS

Tumor volumes were not significantly different among the 3 methods, either before or after CRT (P=.08 to .92). ICCs compared to manual segmentation were 0.80 to 0.91 and 0.53 to 0.66 before and after CRT, respectively, for the automated segmentation and 0.91 to 0.97 and 0.61 to 0.75, respectively, for the semiautomated method. Interobserver agreement (ICC) pre and post CRT was 0.82 and 0.59 for automated segmentation, 0.91 and 0.73 for semiautomated segmentation, and 0.91 and 0.75 for manual segmentation, respectively. Mean DSI between the automated and semiautomated method were 0.83 and 0.58 pre-CRT and post-CRT, respectively; DSI between the automated and manual segmentation were 0.68 and 0.42 and 0.70 and 0.41 between the semiautomated and manual segmentation, respectively. Median measurement time for the radiologists was 0 seconds (pre- and post-CRT) for the automated method, 41 to 69 seconds (pre-CRT) and 60 to 67 seconds (post-CRT) for the semiautomated method, and 180 to 296 seconds (pre-CRT) and 84 to 91 seconds (post-CRT) for the manual method.

CONCLUSIONS

DWI volumetry using a semiautomated segmentation approach is promising and a potentially time-saving alternative to manual tumor delineation, particularly for primary tumor volumetry. Once further optimized, it could be a helpful tool for tumor response assessment in rectal cancer.

Levator hiatal area as a risk factor for cystocele recurrence after surgery: a prospective study

OBJECTIVE

To investigate whether increased levator hiatal area, measured preoperatively, was independently associated with anatom-ical cystocele recurrence 12 months after anterior colporrhaphy.

DESIGN

Multicentre prospective cohort study.

SETTING

Nine teaching hospitals in the Netherlands.

POPULATION

Women planned for conventional anterior colporrhaphy without mesh.

METHODS

Women underwent physical examination, translabial three-dimensional (3D) ultrasound and magnetic resonance imaging (MRI) prior to surgery. At 12 months after surgery the physical examination was repeated.

MAIN OUTCOME MEASURES

Women with and without anatomical cystocele recurrence were compared to assess the association with levator hiatal area on 3D ultrasound, levator hiatal area on MRI, and potential confounding factors. The receiver operating characteristic (ROC) curve was created to quantify the discriminative ability of using levator hiatal area to predict anatomical cystocele recurrence.

RESULTS

Of 139 included women, 76 (54.7%) had anatomical cystocele recurrence. Preoperative stage 3 or 4 and increased levator hiatal area during Valsalva on ultrasound were significantly associated with cystocele recurrence, with odds ratios of 3.47 (95% confidence interval, 95% CI 1.66-7.28) and 1.06 (95% CI 1.01-1.11) respectively. The area under the ROC curve was 0.60 (95% CI 0.51-0.70) for levator hiatal area during Valsalva on ultrasound, and 0.65 (95% CI 0.55-0.71) for preoperative Pelvic Organ Prolapse Quantification (POP-Q) stage.

CONCLUSIONS

Increased levator hiatal area during Valsalva on ultrasound prior to surgery and preoperative stage 3 or 4 are independent risk factors for anatomical cystocele recurrence after anterior colporrhaphy; however, increased levator hiatal area as the sole factor for predicting anatomical cystocele recurrence after surgery shows poor test characteristics.

T-staging of rectal cancer: accuracy of 3.0 Tesla MRI compared with 1.5 Tesla

Objectives

Magnetic resonance imaging (MRI) is not accurate in discriminating T1-2 from borderline T3 rectal tumors. Higher resolution on 3 Tesla-(3T)-MRI could improve diagnostic performance for T-staging. The aim of this study was to determine whether 3T-MRI compared with 1.5 Tesla-(1.5T)-MRI improves the accuracy for the discrimination between T1-2 and borderline T3 rectal tumors and to evaluate reproducibility.

Methods

13 patients with non-locally advanced rectal cancer underwent imaging with both 1.5T and 3T-MRI. Three readers with different expertise evaluated the images and predicted T-stage with a confidence level score. Receiver operator characteristics curves with areas under the curve (AUC) and diagnostic parameters were calculated. Inter- and intra-observer agreements were calculated with quadratic kappa-weighting. Histology was the reference standard.

Results

Seven patients had pT1-2 tumors and six had pT3 tumors. AUCs ranged from 0.66 to 0.87 at 1.5T vs. 0.52–0.82 at 3T. Mean overstaging rate was 43% at 1.5T and 57% at 3T (P = 0.23). Inter-observer agreement was κ 0.50–0.71 at 1.5T vs. 0.15–0.68 at 3T. Intra-observer agreement was κ 0.71 at 1.5T and 0.76 at 3T.

Conclusions

This is the first study to compare 3T with 1.5T MRI for T-staging of rectal cancer within the same patients. Our results showed no difference between 3T and 1.5T-MRI for the distinction between T1-2 and borderline T3 tumors, regardless of expertise. The higher resolution at 3T-MRI did not aid in the distinction between desmoplasia in T1-2-tumors and tumor stranding in T3-tumors. Larger studies are needed to acknowledge these findings.

External ultrasonography of the neck does not add diagnostic value to integrated positron emission tomography-computed tomography (PET-CT) scanning in the diagnosis of cervical lymph node metastases in patients with esophageal carcinoma

One of the objectives of preoperative imaging in esophageal cancer patients is the detection of cervical lymph node metastases. Traditionally, external ultrasonography of the neck has been combined with computed tomography (CT) in order to improve the detection of cervical metastases. In general, integrated positron emission tomography-computed tomography (PET-CT) has been shown to be superior to CT or PET regarding staging and therefore may limit the role of external ultrasonography of the neck. The objective of this study was to determine the additional value of external ultrasonography of the neck to PET-CT. This study included all patients referred our center for treatment of esophageal carcinoma. Diagnostic staging was performed to determine treatment plan. Cervical lymph nodes were evaluated by external ultrasonography of the neck and PET-CT. In case of suspect lymph nodes on external ultrasonography or PET-CT, fine needle aspiration (FNA) was performed. Between 2008 and 2010, 170 out of 195 referred patients underwent both external ultrasonography of the neck and PET-CT. Of all patients, 84% were diagnosed with a tumor at or below the distal esophagus. In 140 of 170 patients, the cervical region was not suspect; no FNA was performed. Seven out of 170 patients had suspect nodes on both PET-CT and external ultrasonography. Five out of seven patients had cytologically confirmed malignant lymph nodes, one of seven had benign nodes, in one patient FNA was not performed; exclusion from esophagectomy was based on intra-abdominal metastases. In one out of 170 patients, PET-CT showed suspect nodes combined with a negative external ultrasonography; cytology of these nodes was benign. Twenty-two out of 170 patients had a negative PET-CT with suspect nodes on external ultrasonography. In 18 of 22 patients, cervical lymph nodes were cytologically confirmed benign; in four patients, FNA was not possible or inconclusive. At a median postoperative follow-up of 15 months, only 1% of patients developed cervical lymph node metastases. This study shows no additional value of external ultrasonography to a negative PET-CT. According to our results, it can be omitted in the primary workup. However, suspect lymph nodes on PET-CT should be confirmed by FNA to exclude false positives if it would change treatment plan.

Protocol for translabial 3D-ultrasonography for diagnosing levator defects (TRUDIL): a multicentre cohort study for estimating the diagnostic accuracy of translabial 3D-ultrasonography of the pelvic floor as compared to MR imaging

BACKGROUND

Pelvic organ prolapse (POP) is a condition affecting more than half of the women above age 40. The estimated lifetime risk of needing surgical management for POP is 11%. In patients undergoing POP surgery of the anterior vaginal wall, the re-operation rate is 30%. The recurrence risk is especially high in women with a levator ani defect. Such defect is present if there is a partially or completely detachment of the levator ani from the inferior ramus of the symphysis. Detecting levator ani defects is relevant for counseling, and probably also for treatment. Levator ani defects can be imaged with MRI and also with Translabial 3D ultrasonography of the pelvic floor. The primary aim of this study is to assess the diagnostic accuracy of translabial 3D ultrasonography for diagnosing levator defects in women with POP with Magnetic Resonance Imaging as the reference standard. Secondary goals of this study include quantification of the inter-observer agreement about levator ani defects and determining the association between levator defects and recurrent POP after anterior repair. In addition, the cost-effectiveness of adding translabial ultrasonography to the diagnostic work-up in patients with POP will be estimated in a decision analytic model.

METHODS/DESIGN

A multicentre cohort study will be performed in nine Dutch hospitals. 140 consecutive women with a POPQ stage 2 or more anterior vaginal wall prolapse, who are indicated for anterior colporapphy will be included. Patients undergoing additional prolapse procedures will also be included. Prior to surgery, patients will undergo MR imaging and translabial 3D ultrasound examination of the pelvic floor. Patients will be asked to complete validated disease specific quality of life questionnaires before surgery and at six and twelve months after surgery. Pelvic examination will be performed at the same time points. Assuming a sensitivity and specificity of 90% of 3D ultrasound for diagnosing levator defects in a population of 120 women with POP, with a prior probability of levator ani defects of 40%, we will be able to estimate predictive values with good accuracy (i.e. confidence limits of at most 10% below or above the point estimates of positive and negative predictive values).Anticipating 3% unclassifiable diagnostic images because of technical reasons, and a further safety margin of 10% we plan to recruit 140 patients.

TRIAL REGISTRATION

Nederlands trial register NTR2220.

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?

PURPOSE

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Linitis plastica of the rectum secondary to bladder carcinoma: a report of two cases and its MR features

Rectal linitis plastica (RLP) is a circumferentially infiltrating intramural anaplastic carcinoma that results in a rigid constricted rectum with thickened walls. A long delay between the onset of symptoms and the diagnosis often occurs because RLP can mimic a lot of diseases and endoscopy and biopsies are often negative, owing to the fact that the mucosa is frequently unaffected in RLP. RLP secondary to bladder cancer is rarely described in the English literature. We present the first report of the MR features of secondary rectal linitis plastica from a bladder carcinoma. Two patients presented with changed bowel habits. All diagnostic tests were inconclusive. In both patients, pelvic T(2) weighted MR images revealed a double-layered thickening of the rectal wall with an inner isointense circumferential thickening of the submucosa and outer hypointense circumferential thickening of the muscular rectal wall. Based on MRI, further investigations were performed and secondary RLP was diagnosed. It is important to establish the diagnosis of RLP early because of its bad prognosis. The value of MRI in supporting the diagnosis of RLP should not be underestimated. As endoscopy plus biopsy can often be negative, we suggest that, if pelvic MRI shows a concentric double layered thickening of the rectal wall over a long segment, then the diagnosis of RLP should be considered. This should prompt further investigations either to confirm or rule out the diagnosis of RLP by performing endoscopy with deep rectal wall biopsies.

Mesorectal fascia invasion after neoadjuvant chemotherapy and radiation therapy for locally advanced rectal cancer: accuracy of MR imaging for prediction

PURPOSE

To retrospectively assess sensitivity and specificity of magnetic resonance (MR) imaging after chemotherapy and radiation therapy for predicting tumor invasion of the mesorectal fascia (MRF) in locally advanced primary rectal cancer, by using results of histologic examination and surgery as the reference standard, and to determine morphologic MR imaging criteria for MRF invasion.

MATERIALS AND METHODS

The Ethical Committee of University Hospital Maastricht approved this study and waived informed consent. Two observers independently scored postchemoradiation MR images in 64 patients with rectal cancer (38 male [mean age, 60 years] and 26 female [mean age, 64 years] patients) for MRF tumor invasion with a confidence level scoring system defined by subjective criteria. In a subsequent consensus reading session, morphologic MR criteria for invasion were defined by comparing morphologic changes with histologic findings. These criteria were evaluated and compared with the subjective criteria by comparing areas under the receiver operating characteristic curves (AUCs).

RESULTS

AUCs of postchemoradiation MR imaging for predicting MRF tumor invasion were 0.81 and 0.82 for observers 1 and 2, respectively. The following four types of morphologic tissue patterns at MR imaging were associated with whether or not MRF invasion was present at histologic examination: (a) development of fat pad larger than 2 mm (seen in no quadrants with and in four quadrants without invasion), (b) development or persistence of spiculations (seen in no quadrants with and in 22 quadrants without invasion), (c) development of diffuse hypointense "fibrotic" tissue (seen in 21 quadrants with and in 32 quadrants without invasion), and (d) persistence of diffuse iso- or hyperintense tissue (seen in 19 quadrants with and in two quadrants without invasion). AUC of postchemoradiation MR imaging for predicting MRF invasion on the basis of morphologic criteria was 0.80. There was no significant difference between the performance of subjective and morphologic criteria (P = .73-.76).

CONCLUSION

Postchemoradiation MR imaging findings have moderate accuracy for predicting tumor invasion of the MRF related to the limitation in differentiating between diffuse "fibrotic" tissue with and that without small tumor foci. Specific other types of morphologic patterns at MR imaging can highly predict a tumor-free or invaded MRF.

Rectal cancer: MR imaging in local staging--is gadolinium-based contrast material helpful?

PURPOSE

To determine retrospectively whether addition of gadolinium-enhanced T1-weighted magnetic resonance (MR) sequence to T2-weighted turbo spin-echo (SE) MR imaging is valuable for preoperative assessment of T stage and circumferential resection margin in patients with primary rectal cancer.

MATERIALS AND METHODS

Local institutional review board approved study and waived informed patient consent. Eighty-three patients with operable primary rectal cancer underwent preoperative MR imaging. Retrospectively, two observers independently scored T2-weighted turbo SE MR images and, in a second reading, T2-weighted images combined with gadolinium-enhanced T1-weighted turbo SE MR images for tumor penetration through rectal wall and tumor extension into mesorectal fascia. A confidence level scoring system was used, and receiver operating characteristic (ROC) curves were generated. Histologic findings were standard of reference. Difference in performance of T2-weighted and combined T2-weighted plus gadolinium-enhanced T1-weighted sequences was analyzed by comparing corresponding areas under ROC curves (A(z)) for each observer. Interobserver agreement was calculated by using linear weighted kappa statistics.

RESULTS

Addition of contrast-enhanced T1-weighted to T2-weighted MR imaging did not significantly improve diagnostic accuracy for prediction of tumor penetration through rectal wall (A(z) of T2-weighted vs T2-weighted plus T1-weighted images for observer 1, 0.740 vs 0.764; observer 2, 0.856 vs 0.768) and tumor extension into mesorectal fascia (A(z) for observer 1, 0.962 vs 0.902; observer 2, 0.902 vs 0.911). Diagnostic performance (A(z)) of MR and interobserver agreement were high for prediction of tumor extension into mesorectal fascia (kappa = 0.61, 0.74) but only moderate for penetration through rectal wall (kappa = 0.47, 0.45).

CONCLUSION

Gadolinium-enhanced MR sequences did not improve diagnostic accuracy for assessment of tumor penetration through rectal wall and tumor extension into mesorectal fascia.

High resolution MRI of anorectal malformation in the newborn: case reports of Currarino syndrome and anocutaneous fistula

To show the accuracy of a high-resolution magnetic resonance imaging (MRI) technique with a phased array coil in diagnosing anorectal malformation, we present two neonates with Currarino syndrome and anocutaneous fistula, respectively. Anatomy was visualized correctly with this technique, but conventional MRI did not show the complete extent of the disease. The reported high-resolution MRI findings concerning these conditions are scanty.