Prognostic significance of MR identified EMVI, tumour deposits, mesorectal nodes and pelvic side wall disease in locally advanced rectal cancer

Circulating Markers of Systemic Inflammation, Measured After Completion of Neoadjuvant Therapy, Associated With Response in Locally Advanced Rectal Cancer

BACKGROUND

The extent of neoadjuvant therapy response, before surgery, is an important prognosticator in locally advanced rectal cancer. A spectrum of response exists, with a dearth of reliable measurements. The host response to treatment remains unexplored. Within operable colorectal cancer, circulating markers of elevated systemic inflammation are associated with poor survival. Studies have suggested that elevated pre-neoadjuvant inflammatory markers, including the modified Glasgow prognostic score and the neutrophil:lymphocyte ratio, are associated with a poorer response.

OBJECTIVE

This study aimed to comprehensively evaluate hematological markers of inflammation before and after neoadjuvant therapy.

DESIGN

Longitudinal cohort study.

SETTINGS

Single health board from a prospectively maintained regional cancer database.

PATIENTS

Consecutive patients with locally advanced rectal cancer who underwent curative-intent neoadjuvant therapy between June 2016 and July 2021.

MAIN OUTCOME MEASURES

Elevated markers of the systemic inflammatory response before and after neoadjuvant therapy.

RESULTS

A total of 278 patients (67.3% men, median age 65 years) were identified. A complete response (clinical or pathological complete response) was achieved in 27.34%, and good tumor regression was achieved in 37.05% (tumor regression grading 0-1). No pre-neoadjuvant marker was found to be associated with response or regression. Multivariate analysis of post-neoadjuvant variables revealed an elevated modified Glasgow prognostic score (OR 2.8; 95% CI, 1.22-6.41; p = 0.015), and an elevated CEA (OR 4.09; 95% CI, 1.6-10.44; p = 0.003) was found to be independently associated with incomplete response. An elevated post-neoadjuvant modified Glasgow prognostic score (OR 2.14; 95% CI, 1.08-4.23; p = 0.029) was also independently associated with poor tumor regression on multivariate analysis.

LIMITATIONS

Retrospective design and slight variation in the timing of post-neoadjuvant blood tests were limitations.

CONCLUSIONS

We report that post-neoadjuvant modified Glasgow prognostic score is associated with poorer response and regression, potentially indicating that radiation resistance is associated with the development of a protumor inflammatory environment. Further work is required to define the local intratumoral processes associated with response and their interrelationship with systemic parameters. Ultimately, there may be a rationale for testing anti-inflammatory strategies in combination with radiotherapy as an option for optimizing treatment response. See Video Abstract .

LOS MARCADORES CIRCULANTES DE INFLAMACIN SISTMICA, MEDIDOS DESPUS DE COMPLETAR LA TERAPIA NEOADYUVANTE, SE ASOCIAN CON LA RESPUESTA EN EL CNCER RECTAL LOCALMENTE AVANZADO

ANTECEDENTES:El grado de respuesta a la terapia neoadyuvante, antes de la cirugía, es un pronosticador importante en el cáncer rectal localmente avanzado. Existe un espectro de respuestas, con una escasez de medidas confiables. La respuesta del huésped al tratamiento permanece inexplorada. Dentro del cáncer colorrectal operable, los marcadores circulantes de inflamación sistémica elevada se asocian con una supervivencia deficiente. Los estudios han sugerido que los marcadores inflamatorios pre-neoadyuvantes elevados, incluidos; el puntaje pronóstico de Glasgow modificado y la proporción neutrófilos::linfocitos, se asocian con una respuesta peor.OBJETIVO:Este estudio tuvo como objetivo evaluar de manera integral los marcadores hematológicos de inflamación antes y después de la terapia neoadyuvante.DISEÑO:Estudio de cohorte longitudinal.ESCENARIO:Junta de salud única de una base de datos de cáncer regional mantenida prospectivamente.PACIENTES:Pacientes consecutivos con cáncer rectal localmente avanzado que se sometieron a terapia neoadyuvante con intención curativa entre; Junio de 2016-julio de 2021.PRINCIPALES MEDIDAS DE RESULTADOS:Marcadores elevados de la respuesta inflamatoria sistémica antes y después de la terapia neoadyuvante.RESULTADOS:278 pacientes. 67,3 % varones, mediana de edad 65. El 27,34 % logró una "respuesta completa" (respuesta completa clínica o patológica). El 37,05 % logró una "buena regresión tumoral" (clasificación de regresión tumoral de 0 a 1). Ningún marcador pre-neoadyuvante se asoció con la respuesta o la regresión. El análisis multivariado de las variables pos-neoadyuvantes reveló un puntaje pronóstico de Glasgow modificado elevado (OR 2,8; IC del 95 % 1,22-6,41; p = 0,015) y un antígeno carcinoembrionario elevado (OR 4,09; IC del 95 % 1,6-10,44; p = 0,003) asociados de forma independiente con una respuesta incompleta. Un puntaje pronóstico de Glasgow modificado post-neoadyuvante elevado (OR 2,14, IC del 95 % 1,08-4,23, p = 0,029) también se asoció de forma independiente con una regresión tumoral deficiente en el análisis multivariable.LIMITACIONES:Diseño retrospectivo. Ligera variación en el momento de los análisis de sangre pos-neoadyuvante.CONCLUSIONES:Informamos que el puntaje pronóstico de Glasgow modificado pos-neoadyuvante se asoció con una respuesta y regresión más deficientes, lo que podría indicar que la resistencia a la radiación está asociada con el desarrollo de un entorno inflamatorio protumoral. Se requieren más estudios para definir los procesos intratumorales locales asociados con la respuesta y su interrelación con los parámetros sistémicos. En última instancia, puede haber una justificación para probar estrategias antiinflamatorias en combinación con radioterapia como una opción para optimizar la respuesta al tratamiento. (Traducción-Dr. Aurian Garcia Gonzalez ).

Research progress in multimodal radiomics of rectal cancer tumors and peritumoral regions in MRI

Rectal cancer (RC) is one of the most common malignant tumors of the digestive system and has an alarmingly high incidence and mortality rate globally. Compared to conventional imaging examinations, radiomics can extract quantitative features that reflect tumor heterogeneity and mine data from medical images. In this review, we discuss the potential value of multimodal MRI-based radiomics in the diagnosis and treatment of RC, with a special emphasis on the role of peritumoral tissue characteristics in clinical decision-making. Existing studies have shown that a radiomics model integrating intratumoral and peritumoral characteristics has good application prospects in RC staging evaluation, efficacy prediction, metastasis monitoring, recurrence early warning, and prognosis judgment. At the same time, this paper also objectively analyzes the existing methodological limitations in this field, including insufficient data standardization, inadequate model validation, limited sample size and poor reproducibility of results. By combining existing evidence, this review aimed to enhance the attention of clinicians and radiologists on the characteristics of peritumoral tissues and promote the translational application of radiomics technology in the individualized treatment of RC.

Risk Factors for Regrowth After Nonoperative Management for Rectal Cancer

BACKGROUND

Among patients with rectal cancer who achieve a complete clinical response (cCR) after neoadjuvant therapy and undergo nonoperative management (NOM), a subset experience tumor regrowth and require salvage surgery. We sought to identify clinicopathologic factors associated with tumor regrowth to assist in patient selection for NOM.

METHODS

Patients treated for rectal cancer at a single National Cancer Institute (NCI)-designated Comprehensive Cancer Center in whom NOM was pursued based on cCR or near-cCR were identified. Patients were stratified based on whether they developed tumor regrowth during follow-up. Tumor and treatment details were compared to identify factors affecting regrowth-free survival (RFS).

RESULTS

Among 125 patients, 26 (20.8%) experienced local regrowth and 8 (6.4%) experienced distant metastasis at a median follow-up of 35 months. Extramural vascular invasion (EMVI) and clinically positive pelvic sidewall lymph nodes (PSW) were associated with worse RFS (hazard ratio [HR] 2.48, 95% confidence interval [CI] 1.08-5.72, p = 0.03; HR 2.77, 95% CI 1.16-6.61, p = 0.002). Among 107 patients eligible for post hoc endoscopic evaluation, those with cCR (n = 80) at first endoscopic re-evaluation had trended towards higher RFS than those with near-cCR (n = 27; HR 2.12, 95% CI 0.95-4.75, p = 0.07), with a significant difference in patients without regrowth at 1 year (HR 5.58, 95% CI 1.23-25.32, p = 0.03).

CONCLUSIONS

Rectal cancer patients with high-risk magnetic resonance imaging (MRI) features, namely EMVI and positive PSW nodes, are more likely to experience tumor regrowth despite an excellent clinical response. Patients with a near-complete endoscopic response may also be at higher risk of later regrowth. The decision to attempt NOM should be carefully weighed against the increased risk of tumor regrowth.

Spectral computed tomography parameters of primary tumors and lymph nodes for predicting tumor deposits in colorectal cancer

BACKGROUND

Tumor deposits (TDs) are an independent predictor of poor prognosis in colorectal cancer (CRC) patients. Enhanced follow-up and treatment monitoring for TD+ patients may improve survival rates and quality of life. However, the detection of TDs relies primarily on postoperative pathological examination, which may have a low detection rate due to sampling limitations.

AIM

To evaluate the spectral computed tomography (CT) parameters of primary tumors and the largest regional lymph nodes (LNs), to determine their value in predicting TDs in CRC.

METHODS

A retrospective analysis was conducted which included 121 patients with CRC whose complete spectral CT data were available. Patients were divided into the TDs+ group and the TDs- group on the basis of their pathological results. Spectral CT parameters of the primary CRC lesion and the largest regional LNs were measured, including the normalized iodine concentration (NIC) in both the arterial and venous phases, and the LN-to-primary tumor ratio was calculated. Statistical methods were used to evaluate the diagnostic efficacy of each spectral parameter.

RESULTS

Among the 121 CRC patients, 33 (27.2%) were confirmed to be TDs+. The risk of TDs positivity was greater in patients with positive LN metastasis, higher N stage and elevated carcinoembryonic antigen and cancer antigen 19-9 levels. The NIC (LNs in both the arterial and venous phases), NIC (primary tumors in the venous phase), and the LN-to-primary tumor ratio in both the arterial and venous phases were associated with TDs (P < 0.05). In multivariate logistic regression analysis, the arterial phase LN-to-primary tumor ratio was identified as an independent predictor of TDs, demonstrating the highest diagnostic performance (area under the curve: 0.812, sensitivity: 0.879, specificity: 0.648, cutoff value: 1.145).

CONCLUSION

The spectral CT parameters of the primary colorectal tumor and the largest regional LNs, especially the LN-to-primary tumor ratio, have significant clinical value in predicting TDs in CRC.

Multiparametric MRI-Based Deep Learning Models for Preoperative Prediction of Tumor Deposits in Rectal Cancer and Prognostic Outcome

RATIONALE AND OBJECTIVES

To investigate the predictive value of a deep learning model based on multiparametric MRI (mpMRI) for tumor deposit (TD) in rectal cancer (RC) patients and to analyze their prognosis.

MATERIALS AND METHODS

Data from 529 RC patients who underwent radical surgery at two centers were retrospectively collected. 379 patients from center one were randomly divided into a training set (n = 265) and an internal validation (invad) set (n = 114) in a 7:3 ratio. 150 patients from center two were included in the external validation (exvad) set. Univariate and multivariate analyses were performed to identify independent clinical predictors and to construct a clinical model. Preoperative mpMRI images were utilized to extract deep features through the ResNet-101 model. Following feature selection, a deep learning model was developed. A nomogram was created by combining the clinical model with the deep learning model. The clinical applicability of each model was assessed using ROC curves, decision curve analysis (DCA), clinical impact curves (CIC), and deLong test. Kaplan-Meier survival analysis was conducted to evaluate prognostic outcome among patients.

RESULTS

Among the 529 patients, 142 (26.8%) were TD positive. In the training set, clinical model was constructed based on clinical independent predictors (cT and cN). 30 deep features were selected to calculate the deep learning radscore (DLRS) and develop the deep learning (DL) model. The AUC values for the clinical model were 0.724, 0.836, and 0.763 in the training set, invad set, and exvad set, respectively. The AUC values for the DL model were 0.903, 0.853, and 0.874, respectively. The nomogram achieved higher AUC values of 0.925, 0.919, and 0.9, respectively. The DeLong test indicated that the predictive performance of the nomogram was superior to both the DL model and the clinical model in training and invad sets. Kaplan-Meier survival analysis showed that both the DL model and the nomogram effectively stratified patients into high-risk and low-risk groups for 3-year DFS (p < 0.05).

CONCLUSION

The nomogram, which integrates mpMRI-based deep radiomic features and clinical characteristics, effectively predicts preoperative TD status in RC. Both the DL model and the nomogram can effectively stratify patients' 3-year DFS risk.

Impact of MRI risk assessment on the survival benefits of neoadjuvant chemoradiotherapy in patients with stage II-III rectal cancer: A retrospective cohort study

PURPOSE

To investigate whether MRI risk factors can be used to predict clinical outcomes and whether MRI risk assessment can be used to select stage II-III rectal cancer patients who may benefit from neoadjuvant chemoradiotherapy (nCRT).

METHODS AND MATERIALS

A total of 947 rectal cancer patients who underwent total mesorectal excision (TME) were retrospectively recruited. An MRI scoring system was established using the cumulative score of three risk factors (mesorectal fascia involvement, extramural venous invasion, and tumour deposits). Patients with mrT3c-T4 stage, N2 stage, or any risk factors were considered MRI high-risk cases of rectal cancer. Cox regression analysis was used to identify independent risk factors for overall survival (OS) and disease-free survival (DFS). Kaplan-Meier curves were generated to show the benefits of nCRT after propensity score matching (PSM).

RESULTS

OS and DFS were more favourable in the MRI low-risk group than in the MRI high-risk group, and the MRI scoring system facilitated prognostic stratification in stage II-III rectal cancer patients. NCRT significantly improved 3-year OS (89.1 % versus 78.8 %, p = 0.001) and 3-year DFS (73.4 % versus 68.0 %, p = 0.030) in the MRI high-risk group. After PSM, OS and DFS were improved in the MRI high-risk group with an MRI score of 1 (OS: HR = 0.432 [95 % CI: 0.214-0.871], p = 0.019; DFS: HR = 0.477 [95 % CI: 0.275-0.825], p = 0.008) and an MRI score of 2 (OS: HR = 0.276 [95 % CI: 0.130-0.586], p = 0.001; DFS: HR = 0.358 [95 % CI: 0.182-0.705], p = 0.003), whereas MRI low-risk patients did not obtain any survival benefit from nCRT.

CONCLUSIONS

MRI-defined high-risk patients with MRI scores of 1 or 2 may benefit from nCRT. Baseline MRI should be given more consideration in nCRT decision-making.

Development and evaluation of the mrTE scoring system for MRI-detected tumor deposits and extramural venous invasion in rectal cancer

PURPOSE

Tumor deposits (TDs) and extramural venous invasion (EMVI) in locally advanced rectal cancer (LARC) are MRI-detectable markers that reflect the invasive and metastatic potential of tumors. However, both mrTDs and mrEMVI are closely associated with peritumoral vascular signals, and they show a high degree of statistical correlation. We developed a novel scoring system that integrates mrTDs and mrEMVI into a single parameter, simplifying the assessment process and capturing the prognostic value of both factors simultaneously.

METHODS

We retrospectively included LARC patients who received neoadjuvant chemoradiotherapy at five centers and proposed a novel MRI-based scoring system, mrTE (derived from mrTDs and mrEMVI), to integrate the prognostic significance of mrEMVI and mrTDs in rectal cancer. The prognostic value of different mrTE scores was evaluated using Kaplan-Meier curves and the Cox model. The predictive accuracy of the new scoring system was evaluated using the integrated area under the ROC curve (iAUC).

RESULTS

A total of 1188 patients with LARC were included in the evaluation cohort to assess the reliability of the novel imaging scoring system. Based on the mrTE scores ranging from 0 to 2, the patients were categorized into three groups. The 3-year disease-free survival rates for the groups were 88.1%, 78.1%, and 51.9% (score 1 vs 0: HR 2.00, 95% CI 1.36-2.93, p < 0.001; score 2 vs 0: HR 4.75, 95% CI 3.61-6.26, p < 0.001). The mrTE scoring system demonstrated superior performance in predicting DFS compared to other clinical and imaging markers, with a higher predictive accuracy (iAUC = 0.707).

CONCLUSIONS

The mrTE scoring system simplifies the clinical assessment of relevant MR markers and has proven to be an effective tool for predicting the prognosis of LARC patients.

Rectal Cancer and Lateral Lymph Node Staging: Interobserver Agreement and Success in Predicting Locoregional Recurrence

Objectives: To evaluate the agreement among radiologists in the evaluation of rectal cancer staging and restaging (after neoadjuvant therapy) and assess whether locoregional recurrence can be predicted with this information. Materials and Methods: Pre-neoadjuvant and after-neoadjuvant therapy magnetic resonance imaging (MRI) examinations of 239 patients diagnosed with locally advanced rectal cancer were retrospectively reviewed by three radiologists. The agreement between the MRI findings (localization of tumor involvement, tumor coverage pattern, external sphincter involvement, mucin content of the mass and lymph node, changes in the peritoneum, MRI T stage, distance between tumor and MRF, submucosal sign, classification of locoregional lymph node, and EMVI) was discussed at the September 2023 meeting of the Society of Abdominal Radiology (SAR) and the interobserver and histopathological findings were examined. The patients were evaluated according to locoregional rectal cancer and lateral lymph node (LLN) staging, and re-staging was performed using MRI images after neoadjuvant treatment. The ability of the locoregional and LLN staging system to predict locoregional recurrence was evaluated. Results: Among the parameters examined, for the MRI T stage and distance between the tumor and the MRF, a moderate agreement (kappa values: 0.61-0.80) was obtained, while for all other parameters, the interobserver agreement was notably high (kappa values 0.81-1.00). LLNs during the restaging with an OR of 2.1 (95% CI = 0.33-4.87, p = 0.004) and a distance between the tumor and the MRF of less than 1 mm with an OR of 2.1 (95% CI = 1.12-3.94, p = 0.023) affected locoregional recurrence. A multivariable Cox regression test revealed that the restaging of lymph nodes among the relevant parameters had an impact on locoregional recurrence, with an OR of 1.6 (95% CI = 0.32-1.82, p = 0.047). With the LLN staging system, an increase in stage was observed in 37 patients (15.5%), and locoregional recurrence was detected in 33 of them (89.2%) (p < 0.001). Conclusions: LLN staging is not only successful in predicting locoregional recurrence among MRI parameters but is also associated with a very high level of interobserver agreement. The presence of positive LLN in the restaging phase is one of the most valuable MRI parameters for poor prognosis.

The Role of Predictive and Prognostic MRI-Based Biomarkers in the Era of Total Neoadjuvant Treatment in Rectal Cancer

The role of magnetic resonance imaging (MRI) in rectal cancer management has significantly increased over the last decade, in line with more personalized treatment approaches. Total neoadjuvant treatment (TNT) plays a pivotal role in the shift from traditional surgical approach to non-surgical approaches such as 'watch-and-wait'. MRI plays a central role in this evolving landscape, providing essential morphological and functional data that support clinical decision-making. Key MRI-based biomarkers, including circumferential resection margin (CRM), extramural venous invasion (EMVI), tumour deposits, diffusion-weighted imaging (DWI), and MRI tumour regression grade (mrTRG), have proven valuable for staging, response assessment, and patient prognosis. Functional imaging techniques, such as dynamic contrast-enhanced MRI (DCE-MRI), alongside emerging biomarkers derived from radiomics and artificial intelligence (AI) have the potential to transform rectal cancer management offering data that enhance T and N staging, histopathological characterization, prediction of treatment response, recurrence detection, and identification of genomic features. This review outlines validated morphological and functional MRI-derived biomarkers with both prognostic and predictive significance, while also exploring the potential of radiomics and artificial intelligence in rectal cancer management. Furthermore, we discuss the role of rectal MRI in the 'watch-and-wait' approach, highlighting important practical aspects in selecting patients for non-surgical management.

Prognostic value of lateral lymph node metastasis in pretreatment MRI for rectal cancer in patients undergoing neoadjuvant chemoradiation followed by surgical resection without lateral lymph node dissection: A systemic review and meta-analysis

PURPOSE

To systematically review and meta-analyze the prognostic significance of lateral lymph node metastasis (LLNM) on pretreatment MRI in patients with rectal cancer who undergo neoadjuvant chemoradiation followed by curative surgical resection without lateral lymph node dissection (LLND).

METHODS

We searched the MEDLINE and EMBASE databases until September 27, 2023, utilizing the following search terms: (rectal OR rectum OR colorectal) AND (lateral OR sidewall) AND (lymph OR node). The QUIPS tool was employed to evaluate methodological quality. We pooled the association between LLNM on pretreatment MRI and outcomes such as local recurrence, distant metastasis, disease-free survival, and overall survival using hazard ratio (HR) and odds ratio (OR) based on random effects model.

RESULTS

We included 9 studies, encompassing 3180 patients. LLNM on pretreatment MRI revealed a significant association with increased local recurrence rates (HR: 4.11; 95 % CI: [1.87, 9.02]) and elevated risks for both disease-free (HR: 1.70; 95 % CI: [1.42, 2.03]) and overall survival (HR: 1.76; 95 % CI: [1.44, 2.15]). As for distant metastasis, our analysis indicated a potential trend towards increased rates, though this did not reach statistical significance (HR: 1.67; 95 % CI: [0.85, 3.27]).

CONCLUSIONS

Our findings underscore the relationship between LLNM and increased local recurrence and compromised disease-free and overall survival. This emphasizes the potential limitations of relying solely on neoadjuvant chemoradiation and highlights the potential need to intensify treatment in select patients.

Baseline MRI predictors of successful organ preservation in the Organ Preservation in Rectal Adenocarcinoma (OPRA) trial

BACKGROUND

Prospective randomized trials have not yet identified baseline features predictive of organ preservation in locally advanced rectal cancers treated with total neoadjuvant therapy and a selective watch-and-wait strategy.

METHODS

This was a secondary analysis of the OPRA trial, which randomized patients with stage II-III rectal adenocarcinoma to receive either induction or consolidation total neoadjuvant therapy. Patients were recommended for total mesorectal excision, or watch and wait based on clinical response at 8 ± 4 weeks after completing treatment. Standardized baseline clinical and radiological variables were collected prospectively. Survival outcomes, including total mesorectal excision-free survival, disease-free survival, and overall survival, were assessed by intention-to-treat analysis. Cox proportional hazards models were used to evaluate associations between baseline variables and survival outcomes.

RESULTS

Of the 324 patients randomized for the OPRA trial, 38 (11.7%) had cT4 tumours, 230 (71.0%) cN-positive disease, 101 (32.5%) mesorectal fascia involvement, and 64 (19.8%) extramural venous invasion. Several baseline features were independently associated with recommendation for total mesorectal excision on multivariable analysis: nodal disease (HR 1.66, 95% c.i. 1.12 to 2.48), extramural venous invasion (HR 1.57, 1.07 to 2.29), mesorectal fascia involvement (HR 1.45, 1.01 to 2.09), and tumour length (HR 1.11, 1.00 to 1.22). Of these, nodal disease (HR 2.02, 1.15 to 3.53) and mesorectal fascia involvement (HR 2.02, 1.26 to 3.26) also predicted worse disease-free survival. Age (HR 1.03, 1.00 to 1.06) was associated with overall survival.

CONCLUSION

Baseline MRI features, including nodal disease, extramural venous invasion, mesorectal fascia involvement, and tumour length, independently predict the likelihood of organ preservation after completion of total neoadjuvant therapy. Mesorectal fascia involvement and nodal disease are associated with disease-free survival.

Assessing neoadjuvant therapy recommendations in 19 national and international guidelines for rectal cancer

BACKGROUND

 Treatment guidelines belong to the most authoritative sources of evidence-based medicine and are widely implemented by health-care providers. Rectal cancer with an annual incidence of over 730,000 new cases and nearly 340,000 deaths worldwide, remains a significant therapeutic challenge. The total mesorectal excision (TME) leads to a dramatic improvement of local control. The addition of neoadjuvant treatment has been proposed to offer further advancement. However, this addition results in significant functional impairment and a decline in the quality of life.

METHODS

This review critically assesses whether the recommendation for neoadjuvant treatment in current international guidelines is substantiated. A comprehensive search was conducted in July 2022 in PubMed resulting in 988 papers published in English between 2012 and 2022. After exclusions and proofs 19 documents remained for further analysis.

RESULTS

Of the 19 guidelines considered in this review, 11 do not recommend upfront surgery, and 12 do not address the issue of functional impairment following multimodal treatment. The recommendation for neoadjuvant therapy relies on outdated references, lacking differentiated strategies based on current utilisation of MRI staging; numerous guidelines recommend neoadjuvant treatment also to subgroups of patients, who may not need this therapy. Also statements regarding conflicts of interest are often not presented.

CONCLUSIONS

An immediate and imperative step is warranted to align the recommendations with the latest available evidence, thereby affording rectal cancer patients a commensurate standard of care. A meticulous assessment of the guideline formulation process has the potential to avert heterogeneity in the future.

The Additional Role of F18-FDG PET/CT in Characterizing MRI-Diagnosed Tumor Deposits in Locally Advanced Rectal Cancer

Rationale: F18-FDG PET/CT may be helpful in baseline staging of patients with high-risk LARC presenting with vascular tumor deposits (TDs), in addition to standard pelvic MRI and CT staging. Methods: All patients with locally advanced rectal cancer that had TDs on their baseline MRI of the pelvis and had a baseline F18-FDG PET/CT between May 2016 and December 2020 were included in this retrospective study. TDs as well as lymph nodes identified on pelvic MRI were correlated to the corresponding nodular structures on a standard F18-FDG PET/CT, including measurements of nodular SUVmax and SUVmean. In addition, the effects of partial volume and spill-in on SUV measurements were studied. Results: A total number of 62 patients were included, in which 198 TDs were identified as well as 106 lymph nodes (both normal and metastatic). After ruling out partial volume effects and spill-in, 23 nodular structures remained that allowed for reliable measurement of SUVmax: 19 TDs and 4 LNs. The median SUVmax between TDs and LNs was not significantly different (p = 0.096): 4.6 (range 0.8 to 11.3) versus 2.8 (range 1.9 to 3.9). For the median SUVmean, there was a trend towards a significant difference (p = 0.08): 3.9 (range 0.7 to 7.8) versus 2.3 (range 1.5 to 3.4). Most nodular structures showing either an SUVmax or SUVmean ≥ 4 were characterized as TDs on MRI, while only two were characterized as LNs. Conclusions: SUV measurements may help in separating TDs from lymph node metastases or normal lymph nodes in patients with high-risk LARC.

Total Neoadjuvant Therapy (TNT) with Full Dose Concurrent Chemotherapy in Locally Advanced Rectal Adenocarcinoma Including Signet Ring and Mucinous Cancers

PURPOSE

Total neoadjuvant therapy (TNT) with pre-operative chemotherapy and chemoradiotherapy results in improved survival and is becoming the new standard of care in locally advanced rectal cancer (LARC). We describe our experience with TNT consisting of induction chemotherapy followed by chemoradiotherapy using full dose 5FU without oxaliplatin.

METHODS

Adults with biopsy-proven, newly diagnosed LARC with high-risk characteristics on pelvic MRI (T4a or T4b, extramural vascular invasion, N2, mesorectal fascia involvement, enlargement/tumor deposits on lateral lymph nodes) were included. The TNT protocol comprised of six biweekly courses of modified FOLFOX6 followed by pelvic RT with four concurrent cycles of biweekly 5-FU 2600 mg/m2 + LV 200 mg/m2 without oxaliplatin to complete 20 uninterrupted weeks of full dose 5FU. Surgery was planned 11-13 weeks after completing chemoradiotherapy.

RESULTS

Eighty-four LARC patients, including 26% with signet-ring cell carcinoma, with high-risk MRI characteristics were treated with the TNT protocol with a 96% completion rate. Significant (> grade 3) toxicities included neutropenia (23.8%), diarrhea (14.2%) anemia (10.7%), and two deaths. The median DFS at 2 years was 22.5 months with better survival noted for those who underwent surgery or had cCR (with NOM) compared to those who did not undergo surgery (due to progression, inadequate regression, or patient preference despite residual disease) -mDFS 27.7 months versus 11.4 months, p =  < 0.0001 and mOS 29.2 months versus 15 months p =  < 0.0001.

CONCLUSION

The hybrid TNT regimen was administered without significant dose delays or interruptions. Toxicity was manageable but with two treatment-related deaths. Ability to undergo surgery after TNT predicted for improved DFS and OS.

Predicting Positive Radial Margin on Restaging MRI of Patients with Low Rectal Cancer: Can We Do Better?

Objective  The aim of this study was to characterize the tissue involving the margin and study if this information will affect margin prediction on restaging magnetic resonance imaging (MRI) in low rectal adenocarcinoma (LRC) patients treated with neoadjuvant long-course chemoradiotherapy (LCCRT). Methods  In this retrospective study of nonmetastatic LRC (distal margin <5 cm from the anal verge) treated with LCCRT followed by surgery, a radiologist blinded to outcome reread the restaging MRI and documented if the radial margin was involved by tumor, fibrosis, or mucin reaction using T2 high-resolution (HR) and diffusion-weighted imaging (DWI). The diagnostic performance of tumor-involving margin on restaging MRI was assessed using surgical histopathology as a reference. Interobserver agreement between three independent radiologists was assessed in a subset. Results  We included 133 patients (80 males and 53 females) with a mean (range) age of 44.7 (21-86) years and 82% of them had well or moderately differentiated adenocarcinoma. Baseline MRI showed T3 ( n  = 58) or T4 ( n  = 60) disease in 89% of the patients. The pathological margin was positive in 21% ( n  = 28) cases. In restaging MRI, the circumferential resection margin (CRM) ≤1 mm in 75.1% ( n  = 100) cases and MRI predicted tumor, fibrosis, and mucin reaction at the margin in 60, 34, and 6%, respectively, and histopathology showed tumor cells in 33, 14.7, and 16.6% of them, respectively. LRC with tumor-involving margin and bad response (MR tumor regression grade [mr-TRG] 3-5) on restaging MRI had fourfold increased risk of positive pathological circumferential resection margin (pCRM). There was moderate and fair inter-reader agreement for the tissue type involving the CRM ( κ  = 0.471) and mr-TRG ( κ  = 0.266), p  < 0.05. The use of both distance criteria and tumor-involving margins improved the diagnostic accuracy for margin prediction from 39 to 66% on restaging MRI. Conclusions  Margin prediction on restaging MRI can be improved by characterizing the tissue type involving the margin in low rectal cancer patients. The inter-reader agreement was moderate for determining the tissue type.

The Multipurpose Usage of Diffusion-Weighted MRI in Rectal Cancer

Background and Objectives: Colorectal cancer is the third most common oncological disease worldwide. The standard treatment of locally advanced rectal tumors is neoadjuvant radiochemotherapy in combination with surgical resection. The choice of specific treatment algorithm is highly dependent on MRI findings. The aim of this study is to show the potential role of ADC measurements in rectal cancer and their usage in different clinical scenarios. Materials and Methods: A total of 135 patients had rectal MRI evaluation. Seventy-five (56%) had histologically proven rectal adenocarcinoma and sixty (44%) were evaluated as rectal disease-free. An ADC measurement in the most prominent region of interest was obtained for all patients. Eighteen patients (24% of the rectal cancer group) had a second MRI after neoadjuvant chemoradiotherapy with comparison of the ADC values at the same region of interest as previously measured. Results: Rectal cancer ADC values were found to be significantly lower than the ones in the control group (p < 0.001). A statistically significant correlation was found when ADC values in rectal tumors of different T stages were compared (p = 0.039)-those with higher T stage as in locally advanced disease showed lower ADC values. Patients with extramural vascular invasion showed significantly lower ADC values (p = 0.01). There was a significant increase in ADC values after treatment (p < 0.001), and a negative correlation was observed (r = -0.6572; p = 0.004)-tumors with low initial ADC values showed a higher increase in ADC. Conclusions: ADC measurements have a complementary role in the assessment of rectal cancer and have the potential to predict the response to chemoradiotherapy and improve the planning of proper treatment strategies.

Complete mesocolic excision for right hemicolectomy: an updated systematic review and meta-analysis

PURPOSE

Complete mesocolic excision improves lymphadenectomy for right hemicolectomy and respects the embryological planes. However, its effect on cancer-free and overall survival is questioned. Therefore, we aimed to determine the potential benefits of the technique by performing a systematic review of the literature and meta-analysis of the available evidence.

METHODS

Web of Science, PubMed/Medline, and Embase were searched on February 22, 2023. Original studies on short- and long-term oncological outcomes of adult patients undergoing right hemicolectomy with complete mesocolic excision as a treatment for primary colon cancer were considered for inclusion. Outcomes were extracted and pooled using a model with random effects.

RESULTS

A total of 586 publications were identified through database searching, and 18 from citation searching. Exclusion of 552 articles left 24 articles for inclusion. Meta-analysis showed that complete mesocolic excision increased the lymph node harvest (5 studies, 1479 patients, MD 9.62, 95% CI 5.83-13.41, p > 0.0001, I2 84%), 5-year overall survival (5 studies, 2381 patients, OR 1.88, 95% CI 1.14-3.09, p = 0.01, I2 66%), 5-year disease-free survival (4 studies, 1376 patients, OR 2.21, 95% CI 1.51-3.23, p < 0.0001, I2 0%) and decreased the incidence of local recurrence (4 studies, 818 patients, OR 0.27, 95% CI 0.09-0.79, p = 0.02, I2 0%) when compared to standard right hemicolectomy. Perioperative morbidity was similar between the techniques (8 studies, 3899 patients, OR 1.04, 95% CI 0.89-1.22, p = 0.97, I2 0%).

CONCLUSION

Meta-analysis of observational and randomised studies showed that right hemicolectomy with complete mesocolic excision for primary right colon cancer improves oncologic results without increasing morbidity/mortality. These results need to be confirmed by high-quality evidence and randomised trials in selected patients to assess who may benefit from the procedure.

Exploration of Malignant Characteristics in Neoadjuvant Chemotherapy-Resistant Rectal Cancer, Focusing on Extramural Lesions

BACKGROUND

Extramural vascular invasion (EMVI) and tumor deposits (TD) are poor prognostic factors in rectal cancer (RC), especially when resistant to neoadjuvant chemotherapy (NAC). We aimed to define differential expression in NAC responders and non-responders with concomitant EMVI and TD.

METHODS

From 52 RC surgical patients, post-NAC resected specimens were extracted, comprising two groups: cases with residual EMVI and TD (NAC-resistant) and cases without (NAC-effective). Proteomic analysis was conducted to define differential protein expression in the two groups. To validate the findings, immunohistochemistry was performed in another cohort that included 58 RC surgical patients. Based on the findings, chemosensitivity and prognosis were compared.

RESULTS

The NAC-resistant group was associated with a lower 3-year disease-free survival rate than the NAC-effective group (p = 0.041). Discriminative proteins in the NAC-resistant group were highly associated with the sulfur metabolism pathway. Among these pathway constituents, selenium-binding protein 1 (SELENBP1) expression in the NAC-resistant group decreased to less than one-third of that of the NAC-effective group. Immunohistochemistry in another RC cohort consistently validated the relationship between decreased SELENBP1 and poorer NAC sensitivity, in both pre-NAC biopsy and post-NAC surgery specimens. Furthermore, decrease in SELENBP1 was associated with a lower 3-year disease-free survival rate (p = 0.047).

CONCLUSIONS

We defined one of the differentially expressed proteins in NAC responders and non-responders, concomitant with EMVI and TD. SELENBP1 was suspected to contribute to NAC resistance and poor prognosis in RC.

Predictive value of infiltrating tumor border configuration of rectal cancer on MRI

BACKGROUND

Infiltrating tumor border configuration (iTBC) is assessed by postoperative pathological examination, thus, is not helpful for preoperative treatment strategies. The study aimed to detect iTBC by magnetic resonance imaging (MRI) and evaluate its predictive value.

MATERIALS AND METHODS

A total of 153 patients with rectal cancer were retrospectively analyzed. Clinicopathological and MRI data mainly including tumor border configuration (TBC) on MRI, MRI-detected extramural vascular invasion (MEMVI), tumor length, tumor growth pattern, maximal extramural depth, pathology-proven lymph node metastasis (PLN) and pathology-proven extramural vascular invasion (PEMVI) were analyzed. The correlation of MRI factors with PEMVI and PLN was analyzed by univariate and multivariate logistic regression analyses. The nomograms were established based on multivariate logistic regression analysis and were confirmed by Bootstrap self-sampling. The receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) were used to evaluate the diagnostic efficiency.

RESULTS

Fifty cases of PEMVI and 48 cases of PLN were found. Forty cases of PEMVI and 34 cases of PLN in 62 cases of iTBC were also found. iTBC, MEMVI and maximal extramural depth were significantly associated with PEMVI and PLN (P < 0.05). iTBC (odds ratio = 3.84 and 3.02) and MEMVI (odds ratio = 7.27 and 3.22) were independent risk factors for PEMVI and PLN. The C-indices of the two nomograms for predicting PEMVI and PLN were 0.863 and 0.752, respectively. The calibration curves and ROC curves of the two nomograms showed that the correlation between the predicted and the actual incidence of PEMVI and PLN was good. The AUCs of iTBC for predicting PEMVI and PLN were 0.793 (95% CI: 0.714-0.872) and 0.721 (95% CI: 0.632-0.810), respectively. The DeLong test showed that the predictive efficiency of the nomogram in predicting PEMVI was better than that of iTBC (P = 0.0009) and MEMVI (P = 0.0095).

CONCLUSION

iTBC and MEMVI are risk factors for PEMVI and pelvic lymph node metastasis. The nomograms based on iTBC show a good performance in predicting PEMVI and pelvic lymph node metastasis, possessing a certain clinical reference value.

TRIAL REGISTRATION

This study was approved by the Ethics Committee of Beijing Friendship Hospital, and individual consent was waived for this retrospective analysis.

Predictive value of lesion morphology in rectal cancer based on MRI before surgery

OBJECTIVE

To explore the relationship of MRI morphology of primary rectal cancer with extramural vascular invasion (EMVI), metastasis and local recurrence.

MATERIALS AND METHODS

This retrospective study included 153 patients with rectal cancer. Imaging factors and histopathological index including nodular projection (NP), cord sign (CS) at primary tumor margin, irregular nodules (IN) of mesorectum, MRI-detected peritoneal reflection invasion (PRI), range of rectal wall invasion (RRWI), patterns and length of tumor growth, maximal extramural depth (EMD), histologically confirmed local node involvement (hLN), MRI T stage, MRI N stage, MRI-detected extramural vascular invasion (mEMVI) and histologically confirmed extramural vascular invasion (hEMVI) were evaluated. Determining the relationship between imaging factors and hEMVI, synchronous metastasis and local recurrence by univariate analysis and multivariable logistic regression, and a nomogram validated internally via Bootstrap self-sampling was constructed based on the latter.

RESULTS

Thirty-eight cases of hEMVI, fourteen cases of synchronous metastasis and ten cases of local recurrence were observed among 52 NP cases. There were 50 cases of mEMVI with moderate consistency with hEMVI (Kappa = 0.614). NP, CS, EMD and mEMVI showed statistically significant differences in the negative and positive groups of hEMVI, synchronous metastasis, and local recurrence. Compared to patients with local mass growth, the rectal tumor with circular infiltration had been found to be at higher risk of synchronous metastasis and local recurrence (P < 0.05). NP and IN remained as significant predictors for hEMVI, and mEMVI was a predictor for synchronous metastasis, while PRI and mEMVI were predictors for local recurrences. The nomogram for predicting hEMVI demonstrated a C-index of 0.868, sensitivity of 86.0%, specificity of 79.6%, and accuracy of 81.7%.

CONCLUSION

NP, CS, IN, large EMD, mEMVI, and circular infiltration are significantly associated with several adverse prognostic indicators. The nomogram based on NP has good predictive performance for preoperative EMVI. mEMVI is a risk factor for synchronous metastasis. PRI and mEMVI are risk factors for local recurrence.

Implication of MRI Risk Stratification System on the Survival Benefits of Adjuvant Chemotherapy After Neoadjuvant Chemoradiotherapy in Patients With Locally Advanced Rectal Cancer

RATIONALE AND OBJECTIVES

To investigate the implication of a Magnetic resonance imaging (MRI) risk stratification system on the selection of patients with locally advanced rectal cancer (LARC) who can benefit from adjuvant chemotherapy (ACT) after neoadjuvant chemoradiotherapy (NCRT).

MATERIALS AND METHODS

This retrospective study included 328 patients with LARC who underwent NCRT and surgery. The median follow-up duration was 79 months (Interquartile range, 66-94 months). Cox logistic regression analysis was used to identify MRI risk factors and develop a risk stratification system to stratify patients into groups with high and low risks. Kaplan-Meier curves of distant metastasis-free survival (DMFS) and overall survival (OS) were used to show the benefits of ACT and stratify results based on the MRI risk stratification system and postoperative pathological staging.

RESULTS

An MRI risk stratification system was built based on four MRI risk factors, including MRI-identified T3b-T4 stage, N1-N2 stage, extramural venous invasion, and tumor deposits. 74 (22.6%) patients with 3-4 MRI risk factors were classified into the MRI high-risk group. ACT could significantly improve 5-year DMFS (19.2% versus 52.1%; p < 0.001) and OS (34.6% versus 75.0%; p < 0.001) for patients in the MRI high-risk group, while ACT had no survival benefit for patients in the MRI low-risk group. The benefits of ACT were not observed in patients with any pathological staging subgroups (ypT0-2N0, ypT3-4N0, and ypN+).

CONCLUSION

Patients in the MRI high-risk group could benefit from ACT, regardless of postoperative pathological staging. Baseline MRI should be considered more in ACT decision-making.

Computed Tomography-based Radiomics Nomogram for the Preoperative Prediction of Tumor Deposits and Clinical Outcomes in Colon Cancer: a Multicenter Study

RATIONALE AND OBJECTIVES

To develop and validate a computed tomography (CT)-based radiomics nomogram for the preoperative prediction of tumor deposits (TDs) and clinical outcomes in patients with colon cancer.

MATERIALS AND METHODS

This retrospective study included 383 consecutive patients with colon cancer from two centers. Radiomics features were extracted from portal venous phase CT images. Least absolute shrinkage and selection operator regression was applied for feature selection and radiomics signature construction. The multivariate logistic regression model was used to establish a radiomics nomogram. The performance of the nomogram was assessed by using receiver operating characteristic curves, calibration curves and decision curve analysis. Kaplan‒Meier survival analysis was used to assess the difference of the overall survival (OS) in the TDs-positive and TDs-negative groups.

RESULTS

The radiomics signature was composed of 11 TDs status related features. The AUCs of the radiomics model in the training cohort, internal validation and external validation cohorts were 0.82, 0.78 and 0.78, respectively. The radiomics nomogram that incorporated the radiomics signature and clinical independent predictors (CT-N, CEA and CA199) showed good calibration and discrimination with AUCs of 0.88, 0.80 and 0.81 in the training cohort, internal validation and external validation cohorts, respectively. The radiomics nomogram-predicted high-risk groups had a worse OS than the low-risk groups (p < 0.001). The radiomics nomogram-predicted TDs was an independent preoperative predictor of OS.

CONCLUSION

The radiomics nomogram based on CT radiomics features and clinical independent predictors could effectively predict the preoperative TDs status and OS of colon cancer.

IMPORTANT FINDINGS

CT-based radiomics nomogram may be applied in the individual preoperative prediction of TDs status in colon cancer. Additionally, there was a significant difference in OS between the high-risk and low-risk groups defined by the radiomics nomogram, in which patients with high-risk TDs had a significantly worse OS, compared with those with low-risk TDs.

[Interpretation of Rectal MRI after Neoadjuvant Treatment in Patients with Rectal Cancer]

MRI is currently the imaging modality of choice to evaluate rectal cancer after neoadjuvant treatment. The purposes of restaging MRI are to assess the resectability of rectal cancer and to decide whether organ preservation strategies can be applied in patients with a complete clinical response. This review article indicates the key MRI features needed to evaluate rectal cancer after neoadjuvant treatment using a systematic approach. Assessment of primary tumor response including MRI findings to predict a complete response is discussed. Additionally, MRI evaluation of the relationship between the primary tumor and adjacent structures, lymph node response, extramural venous invasion, and tumor deposits after neoadjuvant treatment is presented. Knowledge of these imaging features and their clinical relevance may help radiologists provide an accurate and clinically valuable interpretation of restaging rectal MRI.

Biparametric magnetic resonance imaging-based radiomics features for prediction of lymphovascular invasion in rectal cancer

BACKGROUND

Preoperative assessment of lymphovascular invasion(LVI) of rectal cancer has very important clinical significance. However, accurate preoperative imaging evaluation of LVI is highly challenging because the resolution of MRI is still limited. Relatively few studies have focused on prediction of LVI of rectal cancer with the tool of radiomics, especially in patients with negative statue of MRI-based extramural vascular invasion (mrEMVI).The purpose of this study was to explore the preoperative predictive value of biparametric MRI-based radiomics features for LVI of rectal cancer in patients with the negative statue of mrEMVI.

METHODS

The data of 146 cases of rectal adenocarcinoma confirmed by postoperative pathology were retrospectively collected. In the cases, 38 had positive status of LVI. All patients were examined by MRI before the operation. The biparametric MRI protocols included T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI). We used whole-volume three-dimensional method and two feature selection methods, minimum redundancy maximum relevance (mRMR) and least absolute shrinkage and selection operator (LASSO), to extract and select the features. Logistics regression was used to construct models. The area under the receiver operating characteristic curve (AUC) and DeLong's test were used to evaluate the diagnostic performance of the radiomics based on T2WI and DWI and the combined models.

RESULTS

Radiomics models based on T2WI and DWI had good predictive performance for LVI of rectal cancer in both the training cohort and the validation cohort. The AUCs of the T2WI model were 0.87 and 0.87, and the AUCs of the DWI model were 0.94 and 0.92. The combined model was better than the T2WI model, with AUCs of 0.97 and 0.95. The predictive performance of the DWI model was comparable to that of the combined model.

CONCLUSIONS

The radiomics model based on biparametric MRI, especially DWI, had good predictive value for LVI of rectal cancer. This model has the potential to facilitate the clinical recognition of LVI in rectal cancer preoperatively.

Oncological outcome after lateral pelvic lymphadenectomy for low rectal carcinoma: not only an N-status matter

Tumour deposits (TDs), novel pathological entities, should be considered when estimating the regional and systemic spread of rectal carcinoma and formulating treatment strategies. In fact, TDs may have more severe prognostic impact than lymph node positivity or the lymph node ratio. The assessment of the presence of TDs can be performed only through accurate postoperative pathological examination; however, the detection of TDs is not part of any of the procedures currently used to assess preoperative or intraoperative staging. This review aims to analyse and discuss the impact of TDs on the oncological outcome of patients who undergo surgery for advanced low rectal carcinoma. No prospective study has evaluated the impact of lateral pelvic TDs on oncological outcomes following total mesorectal excision with lateral pelvic lymphadenectomy. Although adequate total mesorectal excision allows for the excision of intramesorectal TDs, lateral pelvic lymph node dissection cannot guarantee the removal of lateral pelvic TDs; moreover, it remains to be determined whether surgical excision of lateral pelvic TDs can impact long-term outcomes. However, the identification of lateral pelvic TDs strengthens the 'staging effect' and limits the 'therapeutic effect' of lateral pelvic lymphadenectomy, supporting the rationale for the use of neoadjuvant chemoradiotherapy for rectal cancer. When evaluating the oncological outcomes after total mesorectal excision with lateral pelvic lymphadenectomy, the impact of lateral pelvic TDs should be considered.

Distinguishing mesorectal tumor deposits from metastatic lymph nodes by using diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging in rectal cancer

OBJECTIVES

This study aimed to identify whether apparent diffusion coefficient (ADC) values and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters are helpful in distinguishing mesorectal tumor deposits (TD) from metastatic lymph nodes (MLN) in rectal cancer (RC).

METHODS

Thirty patients (59 lesions, including 30 TD and 29 MLN) with RC who underwent pretreatment-MRI between February 2016 and August 2018 were enrolled. The morphological features, ADC values, and semi-quantitative parameters of DCE-MRI, including relative enhancement (RE), maximum enhancement (ME), maximum relative enhancement (MRE), time to peak (TTP), wash-in rates (WIR), wash-out rates (WOR), brevity of enhancement (BRE), and area under the curve (AUC) were measured on lesions (TD or MLN) and RC. The parameters were compared between TD and MLN, tumor with and without TD group by using Fisher's exact test, independent-samples t-test, and Mann-Whitney U test. The ratio (lesion-to-tumor) of the parameters was compared between TD and MLN. Receiver operating characteristic curve analysis and binary logistic regression analysis were used to assess the diagnostic ability of single and combined metrics for distinguishing TD from MLN.

RESULTS

The morphological features, including size, shape, and border, were significantly different between TD and MLN. TD exhibited significantly lower RE, MRE, RE-ratio, MRE-ratio, ADC_min-ratio, and ADC_mean-ratio than MLN. RE-ratio showed the highest AUC (0.749) and accuracy (77.97%) among single parameters. The combination of DCE-MRI and DWI parameters together showed higher diagnostic efficiency (AUC = 0.825).

CONCLUSIONS

Morphological features, ADC values, and DCE-MRI parameters can preoperatively help distinguish TD from MLN in RC.

KEY POINTS

• DWI and DCE-MRI can facilitate early detection and distinguishing mesorectal TD (tumor deposits) from MLN (metastatic lymph nodes) in rectal cancer preoperatively. • TD has some specific morphological features, including relatively larger size, lower short- to long-axis ratio, irregular shape, and ill-defined border on T2-weighted MR images in rectal cancer. • The combination of ADC values and semi-quantitative parameters of DCE-MRI (RE, MRE) can help to improve the diagnostic efficiency of TD in rectal cancer.

Quantitative Evaluation of Extramural Vascular Invasion of Rectal Cancer by Dynamic Contrast-Enhanced Magnetic Resonance Imaging

This study was carried out to explore the preoperative predictive value of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in extramural vascular invasion (EMVI) in patients with rectal cancer. 124 patients with rectal cancer were randomly divided into two groups, with 62 groups in each group. One group used conventional magnetic resonance imaging (MRI) and was recorded as the control group. The other group used DCE-MRI and was recorded as the experimental group. The diagnostic value was evaluated by comparing the MRI quantitative parameters of EMVI positive and EMVI negative patients, as well as the area under the curve (AUC) of the receiver operating characteristic curve (ROC), diagnostic sensitivity, and specificity of the two groups. The results showed that the Ktrans and Ve values of EMVI positive patients in the experimental group and the control group were 1.08 ± 0.97 and 1.03 ± 0.93, and 0.68 ± 0.29 and 0.65 ± 0.31, respectively, which were significantly higher than those in EMVI negative patients (P < 0.05). The AUC of EMVI diagnosis in the experimental group and the control group were 0.732 and 0.534 (P < 0.05), the sensitivity was 0.913 and 0.765 (P < 0.05), and the specificity was 0.798 and 0.756 (P > 0.05), respectively. In conclusion, DCE-MRI has a higher diagnostic value than conventional MRI in predicting EMVI in patients with rectal cancer, which was worthy of further clinical promotion.