Surgeon assessment of significant rectal polyps using white light endoscopy alone and in comparison to fluorescence-augmented AI lesion classification.

PURPOSE: Perioperative decision making for large (> 2 cm) rectal polyps with ambiguous features is complex. The most common intraprocedural assessment is clinician judgement alone while radiological and endoscopic biopsy can provide periprocedural detail. Fluorescence-augmented machine learning (FA-ML) methods may optimise local treatment strategy. METHODS: Surgeons of varying grades, all performing colonoscopies independently, were asked to visually judge endoscopic videos of large benign and early-stage malignant (potentially suitable for local excision) rectal lesions on an interactive video platform (Mindstamp) with results compared with and between final pathology, radiology and a novel FA-ML classifier. Statistical analyses of data used Fleiss Multi-rater Kappa scoring, Spearman Coefficient and Frequency tables. RESULTS: Thirty-two surgeons judged 14 ambiguous polyp videos (7 benign, 7 malignant). In all cancers, initial endoscopic biopsy had yielded false-negative results. Five of each lesion type had had a pre-excision MRI with a 60% false-positive malignancy prediction in benign lesions and a 60% over-staging and 40% equivocal rate in cancers. Average clinical visual cancer judgement accuracy was 49% (with only 'fair' inter-rater agreement), many reporting uncertainty and higher reported decision confidence did not correspond to higher accuracy. This compared to 86% ML accuracy. Size was misjudged visually by a mean of 20% with polyp size underestimated in 4/6 and overestimated in 2/6. Subjective narratives regarding decision-making requested for 7/14 lesions revealed wide rationale variation between participants. CONCLUSION: Current available clinical means of ambiguous rectal lesion assessment is suboptimal with wide inter-observer variation. Fluorescence based AI augmentation may advance this field via objective, explainable ML methods.

Interrater Agreement of Height Assessment by Rigid Proctoscopy/Rectoscopy for Rectal Carcinoma.

BACKGROUND: Some guidelines for rectal carcinoma consider 12 cm, measured by rigid endoscopy, to be the cutoff tumor height for optional neoadjuvant chemoradiation therapy. Measuring differences of only a few centimeters may predetermine the choice of further therapy. However, rigid endoscopy may exhibit similar operator dependence to most other clinical examination methods. OBJECTIVES: Evaluation of concordance of rigid rectoscopic tumor height measurements performed by 4 experienced examiners, 2 measuring with patients in the lithotomy position and 2 in the left lateral position. Assessment of tumor palpability and distance of the anal verge to the anocutaneous line were also evaluated. DESIGN: This study used a prospective observational design. SETTING: This study was conducted at an academic teaching hospital that is a referral center for colorectal surgery. PATIENTS: There were 50 patients, of whom 35 were men (70%). The median age was 72.5 years (53-88 years). MAIN OUTCOME MEASURES: Interrater agreement of tumor height assessment and tumor height of less than or greater than the 12-cm height limit. RESULTS: With an intraclass correlation coefficient of 0.947 (95% CI, 0.918-0.967, p < 0.001), interrater reliability of tumor height assessment was statistically rated "excellent." Despite this, in 26% of patients, there was no agreement regarding the allocation of the tumor <12- or >12-cm height limit. Furthermore, there was also considerable disagreement concerning tumor palpability and the distance of the anal verge to the anocutaneous line. Patient positioning was not found to influence results. LIMITATIONS: Single-center study. CONCLUSIONS: Rigid rectal endoscopy may not be a sound pivotal basis for the consideration of optional chemoradiation therapy in rectal carcinoma. Application of a universally valid height limit ignores biological variability in body frame, gender, and acquired pelvic descent. Eligibility for neoadjuvant therapy should not rely on height measurements alone. Uniform MRI or CT imaging protocols, based on agreed upon terminology, including factors such as tumor height relative to the pelvic frame and peritoneal reflection, may be an important diagnostic addition to such a decision. See Video Abstract .Clinical trial registration: DRKS00012758 (German National Study Registry), ST-D 406 (German Cancer Society). ACUERDO ENTRE EVALUADORES EN LA EVALUACIN DE LA ALTURA MEDIANTE PROCTO/ RECTOSCOPIA RGIDA PARA EL CARCINOMA DE RECTO: ANTECEDENTES:Algunas guías para el carcinoma de recto consideran que 12 cm, medidos mediante endoscopia rígida, es la altura de corte del tumor para la quimiorradiación neoadyuvante opcional. Por lo tanto, una diferencia de medición de sólo unos pocos centímetros puede predeterminar la elección de una terapia adicional. Sin embargo, la endoscopia rígida puede presentar una dependencia del operador similar a la de la mayoría de los demás métodos de examen clínico.OBJETIVOS:Evaluación de la concordancia de las mediciones de la altura del tumor rectoscópico rígido realizadas por cuatro examinadores experimentados, dos en litotomía y dos en posición lateral izquierda. También se evaluó la evaluación de la palpabilidad del tumor y la distancia del borde anal a la línea anocutánea.DISEÑO:Estudio observacional prospectivo.LUGAR:Hospital universitario, centro de referencia para cirugía colorrectal.PACIENTES:50 pacientes, 35 varones (70%), mediana de edad 72,5 años (53-88 años).PRINCIPALES MEDIDAS DE RESULTADOS:Acuerdo entre evaluadores en la evaluación de la altura del tumor y la asignación del tumor por debajo o más allá del límite de altura de 12 cm.RESULTADOS:Con un coeficiente de correlación intraclase de 0,947 (IC del 95%: 0,918-0,967, p < 0,001), la confiabilidad entre evaluadores de la evaluación de la altura del tumor se calificó estadísticamente como "excelente". A pesar de esto, en el 26% de los pacientes no hubo acuerdo sobre la asignación del tumor por debajo o por encima del límite de 12 cm de altura. Además, también hubo un considerable desacuerdo con respecto a la palpabilidad del tumor y la distancia del borde anal a la línea anocutánea. No se encontró que la posición del paciente influyera en los resultados.LIMITACIONES:Estudio unicéntrico.CONCLUSIONES:La endoscopia rectal rígida puede no ser una base sólida y fundamental para considerar la quimiorradiación opcional en el carcinoma de recto. La aplicación de un límite de altura universalmente válido obviamente ignora la variabilidad biológica en la constitución corporal, el género y el descenso pélvico adquirido. La elegibilidad para la terapia neoadyuvante no debe depender únicamente de las mediciones de altura. Los protocolos uniformes de imágenes por resonancia magnética o tomografía computarizada, basados en una terminología acordada, incluidos factores como la altura del tumor en relación con la estructura pélvica y la reflexión peritoneal, pueden ser una adición diagnóstica importante para tal decisión. (Traducción-Yesenia Rojas-Khalil )Clinical trial registration: DRKS00012758 (German National Study Registry), ST-D 406 (German Cancer Society).

Machine learning-based response assessment in patients with rectal cancer after neoadjuvant chemoradiotherapy: radiomics analysis for assessing tumor regression grade using T2-weighted magnetic resonance images.

PURPOSE: This study aimed to assess tumor regression grade (TRG) in patients with rectal cancer after neoadjuvant chemoradiotherapy (NCRT) through a machine learning-based radiomics analysis using baseline T2-weighted magnetic resonance (MR) images. MATERIALS AND METHODS: In total, 148 patients with locally advanced rectal cancer(T2-4 or N+) who underwent MR imaging at baseline and after chemoradiotherapy between January 2010 and May 2021 were included. A region of interest for each tumor mass was drawn by a radiologist on oblique axial T2-weighted images, and main features were selected using principal component analysis after dimension reduction among 116 radiomics and three clinical features. Among eight learning models that were used for prediction model development, the model showing best performance was selected. Treatment responses were classified as either good or poor based on the MR-assessed TRG (mrTRG) and pathologic TRG (pTRG). The model performance was assessed using the area under the receiver operating curve (AUROC) to classify the response group. RESULTS: Approximately 49% of the patients were in the good response (GR) group based on mrTRG (73/148) and 26.9% based on pTRG (28/104). The AUCs of clinical data, radiomics models, and combined radiomics with clinical data model for predicting mrTRG were 0.80 (95% confidence interval [CI] 0.73, 0.87), 0.74 (95% CI 0.66, 0.81), and 0.75(95% CI 0.68, 0.82), and those for predicting pTRG was 0.62 (95% CI 0.52, 0.71), 0.74 (95% CI 0.65, 0.82), and 0.79 (95% CI 0.71, 0.87). CONCLUSION: Radiomics combined with clinical data model using baseline T2-weighted MR images demonstrated feasible diagnostic performance in predicting both MR-assessed and pathologic treatment response in patients with rectal cancer after NCRT.

Multiparametric MRI subregion radiomics for preoperative assessment of high-risk subregions in microsatellite instability of rectal cancer patients: a multicenter study.

BACKGROUND: Microsatellite instability (MSI) is associated with treatment response and prognosis in patients with rectal cancer (RC). However, intratumoral heterogeneity limits MSI testing in patients with RC. The authors developed a subregion radiomics model based on multiparametric MRI to preoperatively assess high-risk subregions with MSI and predict the MSI status of patients with RC. METHODS: This retrospective study included 475 patients (training cohort, 382; external test cohort, 93) with RC from two participating hospitals between April 2017 and June 2023. In the training cohort, subregion radiomic features were extracted from multiparametric MRI, which included T2-weighted, T1-weighted, diffusion-weighted, and contrast-enhanced T1-weighted imaging. MSI-related subregion radiomic features, classical radiomic features, and clinicoradiological variables were gathered to build five predictive models using logistic regression. Kaplan-Meier survival analysis was conducted to explore the prognostic information. RESULTS: Among the 475 patients [median age, 64 years (interquartile range, IQR: 55-70 years); 304 men and 171 women], the prevalence of MSI was 11.16% (53/475). The subregion radiomics model outperformed the classical radiomics and clinicoradiological models in both training [area under the curve (AUC)=0.86, 0.72, and 0.59, respectively] and external test cohorts (AUC=0.83, 0.73, and 0.62, respectively). The subregion-clinicoradiological model combining clinicoradiological variables and subregion radiomic features performed the optimal, with AUCs of 0.87 and 0.85 in the training and external test cohorts, respectively. The 3-year disease-free survival rate of MSI groups predicted based on the model was higher than that of the predicted microsatellite stability groups in both patient cohorts (training, P =0.032; external test, P =0.046). CONCLUSIONS: The authors developed and validated a model based on subregion radiomic features of multiparametric MRI to evaluate high-risk subregions with MSI and predict the MSI status of RC preoperatively, which may assist in individualized treatment decisions and positioning for biopsy.

Endosonography Elastography and Magnetic Resonance Imaging in the Restaging and Response Assessment of Rectal Cancer After Neoadjuvant Therapy.

ABSTRACT: The objective of this academic research is to assess the efficacy of conventional endorectal ultrasound (ERUS), ultrasonic shear wave elastography (SWE), and magnetic resonance imaging (MRI) techniques in evaluating the impact of neoadjuvant therapy (nCRT). Forty-five patients with advanced low rectal cancer (T ≥ 3) were included. Before and after nCRT, ERUS, SWE, and MRI evaluations were conducted. The T staging of ultrasound (uT) and MRI (mT) were evaluated and compared with the pathological T staging (ypT). The accuracy of the 2 diagnostic methods for T staging, and T downstaging was evaluated. The ultrasound elasticity difference and relative elasticity before and after treatment and pathological T downstaging were compared, and its cutoff value and the area under the curve were assessed. In terms of T staging accuracy after chemoradiotherapy, the values for ERUS, ERUS combined with SWE, and MRI were 64.4%, 71.1%, and 62.2%, respectively. No significant difference was observed among these groups ( P > 0.05). The accuracy of uT downstaging was 84.4%, and that of mT downstaging was 88.9%. The receiver operating characteristic curve of uLD and elastic differences and relative elasticity of T downstaging after treatment were 0.754, 0.817, and 0.886, respectively (all P < 0.05). Both ERUS and MRI can evaluate ypT downstaging. The indicators for evaluating T downstaging are uLD, elasticity difference, and relative elasticity, providing more reference for clinical assessment of nCRT efficacy.

Acoustic resolution photoacoustic Doppler flowmetry for assessment of patient rectal cancer blood perfusion.

Significance: Photoacoustic Doppler flowmetry offers quantitative blood perfusion information in addition to photoacoustic vascular contrast for rectal cancer assessment. Aim: We aim to develop and validate a correlational Doppler flowmetry utilizing an acoustic resolution photoacoustic microscopy (AR-PAM) system for blood perfusion analysis. Approach: To extract blood perfusion information, we implemented AR-PAM Doppler flowmetry consisting of signal filtering and conditioning, A-line correlation, and angle compensation. We developed flow phantoms and contrast agent to systemically investigate the flowmetry's efficacy in a series of phantom studies. The developed correlational Doppler flowmetry was applied to images collected during in vivo AR-PAM for post-treatment rectal cancer evaluation. Results: The linearity and accuracy of the Doppler flow measurement system were validated in phantom studies. Imaging rectal cancer patients treated with chemoradiation demonstrated the feasibility of using correlational Doppler flowmetry to assess treatment response and distinguish residual cancer from cancer-free tumor bed tissue and normal rectal tissue. Conclusions: A new correlational Doppler flowmetry was developed and validated through systematic phantom evaluations. The results of its application to in vivo patients suggest it could be a useful addition to photoacoustic endoscopy for post-treatment rectal cancer assessment.

Improved effects of the b-value for 2000 sec/mm2 DWI on an accurate qualitative and quantitative assessment of rectal cancer.

BACKGROUND AND STUDY OBJECTIVES: A higher b-value Diffusion-weighted imaging (DWI) would improve the contrast between cancerous and noncancerous tissue. Apparent diffusion coefficient (ADC)-histogram analysis is a method that can provide statistical data and quantitative information on tumor heterogeneity. This study aimed to compare two high b-values (1000 and 2000 sec/mm2) DWI in tumor detection and diagnostic performance in identifying early-stage tumor rectal cancer. PATIENTS AND METHODS: This blinded and blinded retrospective study involved 56 patients with rectal cancer and 45 patients. Two radiologists evaluated the qualitative detection parameters and quantitative parameters of the ADC evaluated histogram and compared them between two DWI sequences (b-value for 1000 sec/mm2 and 2000 sec/mm2). The characteristic curves were used to assess diagnostic administration for the ADC histogram in discriminating early-stage tumors. RESULTS: The b-value for 2000 sec/mm2 DWI significantly improved AUCs, sensitivity, specificity, and precision and decreased false-positive rate for detection compared to the b-value for 1000 sec/mm2 (p < 0.05). The mean and fifth percentile ADC value for stage I using the b-value for 1000 sec/mm2 DWI was significantly higher than stage ≥ II (p = 0.036II and 0.016 respectively), as the well as fifth, 10th, mean ADC of the fifth, 10th, and 25th ADC percentile at b-value for 2000 sec/mm2 (p = 0.031, 0.014, 0.035 and 0.025 respectively). The AUCs of the fifth percentile ADC at b-value for 2000 sec/mm2 DWI in both readers in differentiating the stage Ⅰ tumor were the highest (0.732 and 0.751). CONCLUSION: The b-value for 2000 sec/mm2 DWI could improve the accurate detection of rectal cancer. The fifth percentile ADC at b-value for 2000 sec/mm2 sec/mm2 DWI was more useful for discriminating early stage than the b-value for 1000 sec/mm2 DWI.

The Crying Need for a Better Response Assessment in Rectal Cancer.

OPINION STATEMENT: Since total neoadjuvant treatment achieves almost 30% pathologic complete response, organ preservation has been increasingly debated for good responders after neoadjuvant treatment for patients diagnosed with rectal cancer. Two organ preservation strategies are available: a watch and wait strategy and a local excision strategy including patients with a near clinical complete response. A major issue is the selection of patients according to the initial tumor staging or the response assessment. Despite modern imaging improvement, identifying complete response remains challenging. A better selection could be possible by radiomics analyses, exploiting numerous image features to feed data characterization algorithms. The subsequent step is to include baseline and/or pre-therapeutic MRI, PET-CT, and CT radiomics added to the patients' clinicopathological data, inside machine learning (ML) prediction models, with predictive or prognostic purposes. These models could be further improved by the addition of new biomarkers such as circulating tumor biomarkers, molecular profiling, or pathological immune biomarkers.

Multimodal assessment after total neoadjuvant therapy versus standard neoadjuvant chemoradiotherapy in locally advanced rectal cancer accurately predicts complete responders.

PURPOSE: This study aimed to compare local regrowth rates after total neoadjuvant therapy (TNT) versus standard neoadjuvant chemoradiotherapy (SNCRT) in locally advanced rectal cancer (LARC) patients that were strictly selected and assessed with a multimodal approach. Secondary outcomes were 4-year disease-free (DFS) and overall survival (OS) rates. METHODS: Locally advanced rectal cancer patients without distant metastases treated at Koç Healthcare Group between January 2014 and January 2021 were included. Patients were assessed for complete response with a combination of digital rectal exam, endoscopy, and magnetic resonance imaging with a dedicated rectum protocol. The systemic evaluation was performed with an upper abdomen MRI using intravenous hepatobiliary contrast agent and a thorax CT. RESULTS: Of the 270 patients with LARC, 182 fulfilled the inclusion criteria. Ninety-seven (53.3%) underwent TNT, while 85 (46.7%) underwent SNCRT. A cumulative combination of pathological and sustained clinical complete response was significantly higher in the TNT group than in the SNCRT (45.4% vs. 20.0%, p < 0.0001). After a median follow-up of 48 months, seven patients in the W&W group had regrowth [TNT: 4 (10.8%) vs. SNCRT: 3 (23.1%), p = 0.357]. Based on pathological examination, complete/near complete mesorectum rates (p = 1.000) and circumferential resection margin positivity rates (p = 1.000) were similar between the groups. The 4-year DFS and OS rates were comparable. The patients with clinical or pathological complete response had significantly longer overall survival (p = 0.017) regardless of the type of neoadjuvant treatment. CONCLUSIONS: Multimodal assessment after TNT effectively detects complete responders, resulting in low local recurrence and increased cumulative complete response rates. However, these outcomes did not translate into a survival advantage.

DIAGNOSTICS OF LYMPHOGENIC METASTASIS IN PATIENTS WITH RECTAL CANCER BY COMBINING MRI WITH BLOOD CEA ASSESSMENT.

AIM: To improve the diagnostics of lymphogenic metastasis in patients with rectal cancer (RCa) by combining magnetic resonance imaging (MRI) with the blood carcinoembryonic antigen (CEA) level assessment. MATERIALS AND METHODS: We have systematized and analyzed the results of the examination and treatment of 77 patients with stage II-III rectal adenocarcinoma (T2-3N0-2M0). Before the start of neoadjuvant treatment as well as 8 weeks after its completion, computed tomography (CT) and MRI were performed. We analyzed such prognostic criteria as the size, shape, and structure of lymph nodes as well as the patterns of contrast accumulation. As a prognostic marker, CEA levels in the blood of patients with RCa before surgical treatment were assessed. RESULTS: Radiological exams showed a rounded shape and heterogeneous structure to be the most informative for predicting metastatic lymph node damage, increasing the probability by 4.39 and 4.98 times, respectively. After neoadjuvant treatment, the percentage of positive histopathological reports on lymph node involvement decreased significantly to 21.6% (р ˂ 0.001). MRI showed 76% sensitivity and 48% specificity for assessing lymphogenic metastasis. CEA levels differed significantly between stages II and III (N1-2) (р ˂ 0.032) with a threshold value of 3.95 ng/ml. CONCLUSIONS: In order to increase the effectiveness of the diagnosis of lymphogenic metastasis using radiological examination methods in RCa patients, such prognostic criteria as the round shape and heterogeneous structure of the lymph nodes and the threshold level of CEA should be considered.

Magnetic resonance imaging in preoperative assessment of the mesorectal nodal status of patients with rectal cancer - Can it be trusted?

PURPOSE: Magnetic resonance imaging (MRI) is a fundamental diagnostic modality for the evaluation of primary rectal cancer, but MRI assessment of nodal involvement remains a confounding factor. METHOD: This prospective cohort study was conducted to investigate the accuracy of preoperative MRI in the assessment of nodal status by comparing histopathology reports to MRI findings on a node-by-node basis in 69 patients with rectal cancer. RESULTS: Primary surgery was performed in 40 (58.0%) patients; 29 (42.0%) study patients underwent neoadjuvant chemoradiotherapy (CRT). Histopathological examination revealed T1 tumour in 8 (11.6%) patients, T2 tumour in 30 (43.5%), and T3 tumour in 25 (36.2%). In total, 897 lymph nodes (LNs) have been harvested (13.1 ± 5.4 LNs per specimen). There were 77 MRI-suspicious LNs, 21 (27.3%) of which were histologically proven malignant. The sensitivity of MRI for assessing nodal involvement was 51.2% and specificity 93.4%. Of the 28 patients with MRI-suspicious LNs the diagnosis was correct in 42.8%. The MRI accuracy was 33.3% in "primary surgery" subgroup (n = 18, malignant LNs found in 6 patients). Diagnosis of MRI-negative LNs was correct in 90.2% of study patients; malignant nodes were found in 9.8% of patients initially classified as cN0. CONCLUSIONS: MRI prediction of nodal status in patients with rectal cancer has very low accuracy. Decisions regarding neoadjuvant CRT should not be based on MRI assessment of nodal status, but on the MRI evaluation of tumour depth invasion (T stage and relationship between the tumour and mesorectal fascia).

Predicting lymphovascular invasion in rectal cancer: evaluating the performance of golden-angle radial sparse parallel MRI for rectal perfusion assessment.

This study aims to determine whether the dual-parameter approach combined with either time-resolved angiography with stochastic trajectories (TWIST) or golden-angle radial sparse parallel (GRASP) and diffusion-weighted imaging (DWI) has superior diagnostic performance in predicting pathological lymphovascular invasion (pLVI) rectal cancer when compared with traditional single-parameter evaluations using DWI alone. Patients with pathologically confirmed rectal cancer were enrolled. Perfusion (influx forward volume transfer constant [Ktrans] and rate constant [Kep]) and apparent diffusion coefficient (ADC) were measured by two researchers. For both sequences, areas under receiver operating characteristic (ROCs) to predict pLVI-positive rectal cancer were compared. A total of 179 patients were enrolled in our study. A combined analysis of ADC and perfusion parameters (Ktrans) acquired with GRASP yielded a higher diagnostic performance compared with diffusion parameters alone (area under the curve, 0.91 ± 0.03 vs. 0.71 ± 0.06, P < 0.001); However, ADC with GRASP-acquired Kep and ADC with TWIST-acquired perfusion parameters (Ktrans or Kep) did not offer any additional benefit. The Ktrans of the GRASP technique improved the diagnostic performance of multiparametric MRI to predict rectal cancers with pLVI-positive. In contrast, TWIST did not achieve this effect.

Blood Perfusion Assessment by Indocyanine Green Fluorescence Imaging for Minimally Invasive Rectal Cancer Surgery (EssentiAL trial): A Randomized Clinical Trial.

OBJECTIVE: The aim of the present randomized controlled trial was to evaluate the superiority of indocyanine green fluorescence imaging (ICG-FI) in reducing the rate of anastomotic leakage in minimally invasive rectal cancer surgery. BACKGROUND: The role of ICG-FI in anastomotic leakage in minimally invasive rectal cancer surgery is controversial according to the published literature. METHODS: This randomized, open-label, phase 3, trial was performed at 41 hospitals in Japan. Patients with clinically stage 0-III rectal carcinoma less than 12 cm from the anal verge, scheduled for minimally invasive sphincter-preserving surgery were preoperatively randomly assigned to receive a blood flow evaluation by ICG-FI (ICG+ group) or no blood flow evaluation by ICG-FI (ICG- group). The primary endpoint was the anastomotic leakage rate (grade A+B+C, expected reduction rate of 6%) analyzed in the modified intention-to-treat population. RESULTS: Between December 2018 and February 2021, a total of 850 patients were enrolled and randomized. After the exclusion of 11 patients, 839 were subject to the modified intention-to-treat population (422 in the ICG+ group and 417 in the ICG- group). The rate of anastomotic leakage (grade A+B+C) was significantly lower in the ICG+ group (7.6%) than in the ICG- group (11.8%) (relative risk, 0.645; 95% confidence interval 0.422-0.987; P =0.041). The rate of anastomotic leakage (grade B+C) was 4.7% in the ICG+ group and 8.2% in the ICG- group ( P =0.044), and the respective reoperation rates were 0.5% and 2.4% ( P =0.021). CONCLUSIONS: Although the actual reduction rate of anastomotic leakage in the ICG+ group was lower than the expected reduction rate and ICG-FI was not superior to white light, ICG-FI significantly reduced the anastomotic leakage rate by 4.2%.

MRI Assessment of Extramural Venous Invasion Before and After Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer and Its Association with Disease-Free and Overall Survival.

BACKGROUND: Extramural venous invasion (EMVI) on baseline MRI is associated with poor prognosis in patients with locally advanced rectal cancer. This study investigated the association of persistent EMVI after total neoadjuvant therapy (TNT) (chemoradiotherapy and systemic chemotherapy) with survival. METHODS: Baseline MRI, post-TNT MRI, and surgical pathology data from 175 patients with locally advanced rectal cancer who underwent TNT and total mesorectal excision between 2010 and 2017 were retrospectively analyzed for evidence of EMVI. Two radiologists assessed EMVI status with disagreement adjudicated by a third. Pathologic EMVI status was assessed per departmental standards. Cox regression models evaluated the associations between EMVI and disease-free and overall survival. RESULTS: EMVI regression on both post-TNT MRI and surgical pathology was associated with disease-free survival (hazard ratio, 0.17; 95% confidence interval (CI), 0.04-0.64) and overall survival (hazard ratio, 0.11; 95% CI, 0.02-0.68). In an exploratory analysis of 35 patients with EMVI on baseline MRI, only six had EMVI on pathology compared with 18 on post-TNT MRI; these findings were not associated (p = 0.2). Longer disease-free survival was seen with regression on both modalities compared with remaining positive. Regression on pathology alone, independent of MRI EMVI status, was associated with similar improvements in survival. CONCLUSIONS: Baseline EMVI is associated with poor prognosis even after TNT. EMVI regression on surgical pathology is common even with persistent EMVI on post-TNT MRI. EMVI regression on surgical pathology is associated with improved DFS, while the utility of post-TNT MRI EMVI persistence for decision-making and prognosis remains unclear.

High-resolution integrated dynamic shimming diffusion-weighted imaging (DWI) in the assessment of rectal cancer.

OBJECTIVES: To investigate the feasibility of high-resolution integrated dynamic shimming echo planar imaging (iEPI) applied to rectal cancer. METHODS: A total of seventy-eight patients with non-mucinous rectum adenocarcinoma were enrolled in this study. Using a prototype high-resolution iEPI sequence, high-resolution single-shot EPI (sEPI) sequence, and sEPI sequence, subjective and objective assessment and apparent diffusion coefficient (ADC) value were measured for comparison. The spearman rank correlation analysis test and the receiver operating characteristic curve were performed to evaluate correlation between tumor ADC values, corresponding T stage, and differentiation degree of rectal cancer. RESULTS: The subjective assessment of the image quality (IQ) of high-resolution iEPI was rated superior to high-resolution sEPI and sEPI by both readers (p < 0.001). Signal-to-noise ratio, contrast-to-noise, and signal-intensity ratio were significantly higher in high-resolution iEPI than the other two sequences (p < 0.001). There was no significant difference of tumor ADC values among three EPI sequences in the group of low- to well-differentiated rectal cancer. An inverse correlation was noted between ADC values on three DWI sequences and pathological T stage of rectal cancer (r = - 0.693, - 0.689, - 0.640, p < 0.001). The AUC values of high-resolution iEPI, high-resolution sEPI, and sEPI in predicting well-differentiated rectal cancer were 0.910, 0.761, and 0.725 respectively. CONCLUSIONS: In conclusion, the high-resolution iEPI provided significantly higher IQ and stable ADC compared to another two sequences. High-resolution iEPI has the highest efficacy among three examined sequences in differentiation of rectal cancer with different degrees of differentiation. KEY POINTS: • High-resolution iEPI provided a significantly better IQ than high-resolution sEPI and sEPI when assessing rectal cancer. • The AUC of high-resolution sEPI was the highest among three EPI sequences in predicting well-differentiated rectal cancer.

MRI assessment of rectal cancer response to neoadjuvant therapy: a multireader study.

OBJECTIVES: A watch and wait strategy with the goal of organ preservation is an emerging treatment paradigm for rectal cancer following neoadjuvant treatment. However, the selection of appropriate patients remains a challenge. Most previous efforts to measure the accuracy of MRI in assessing rectal cancer response used a small number of radiologists and did not report variability among them. METHODS: Twelve radiologists from 8 institutions assessed baseline and restaging MRI scans of 39 patients. The participating radiologists were asked to assess MRI features and to categorize the overall response as complete or incomplete. The reference standard was pathological complete response or a sustained clinical response for > 2 years. RESULTS: We measured the accuracy and described the interobserver variability of interpretation of rectal cancer response between radiologists at different medical centers. Overall accuracy was 64%, with a sensitivity of 65% for detecting complete response and specificity of 63% for detecting residual tumor. Interpretation of the overall response was more accurate than the interpretation of any individual feature. Variability of interpretation was dependent on the patient and imaging feature investigated. In general, variability and accuracy were inversely correlated. CONCLUSIONS: MRI-based evaluation of response at restaging is insufficiently accurate and has substantial variability of interpretation. Although some patients' response to neoadjuvant treatment on MRI may be easily recognizable, as seen by high accuracy and low variability, that is not the case for most patients. KEY POINTS: • The overall accuracy of MRI-based response assessment is low and radiologists differed in their interpretation of key imaging features. • Some patients' scans were interpreted with high accuracy and low variability, suggesting that these patients' pattern of response is easier to interpret. • The most accurate assessments were those of the overall response, which took into consideration both T2W and DWI sequences and the assessment of both the primary tumor and the lymph nodes.

Response assessment of locally advanced rectal cancer after neoadjuvant chemoradiotherapy: Is apparent diffusion coefficient useful on 3 T magnetic resonance imaging?

AIM: To assess the diagnostic value of apparent diffusion coefficient (ADC) on 3 T device for the prediction of tumoral response to neoadjuvant chemoradiotherapy (nCRT) and for the response assessment after nCRT in patients with locally advanced rectal cancer (LARC), using pathology as a reference. METHODS: Forty-one patients affected by LARC undergoing 3.0 T MRI before and after nCRT were retrospectively selected. After the conventional acquisition of high resolution T2-weighted sequences, diffusion-weighted MRI (DW-MRI) was performed using a spin-echo echo-planar sequence with multiple b values (150, 500, 1000, 1500 s/mm2 ). Fitted ADC values were calculated for each rectal lesion before and after nCRT by drawing a hand-made region of interest (ROI) around the tumour outline. All patients underwent surgery and pathological staging (classified according to tumour regression grading [TRG] and to tumour and node [TN]) represented the reference standard. Pretreatment ADC value (pre-ADC), ADC value obtained after nCRT (post-ADC) and the difference between post-ADC and pre-ADC (ΔADC) were correlated with both the TRG classes and the TN staging system in each patient. RESULTS: The ADC values obtained in the post nCRT examination and the ΔADC were statistically related both to TRG (p = 0.0004; p = 0.0126, respectively) and TN (p = 0.0484; p = 0.0673, respectively) stages at histopathology. On the contrary, the pre-ADC was not related either to the TRG classes or to the lesion TN staging system (p > 0.05). CONCLUSIONS: 3 T DW-MRI using ADC value can be useful to assess the efficacy of nCRT in LARC; in fact, post-ADC and ΔADC values improve MR capability to evaluate tumour response.

Deep learning-based imaging reconstruction for MRI after neoadjuvant chemoradiotherapy for rectal cancer: effects on image quality and assessment of treatment response.

PURPOSE: To investigate the effects of deep learning-based imaging reconstruction (DLR) on the image quality of MRI of rectal cancer after chemoradiotherapy (CRT), and its accuracy in diagnosing pathological complete responses (pCR). METHODS: We included 39 patients (men: women, 21:18; mean age ± standard deviation, 59.1 ± 9.7 years) with mid-to-lower rectal cancer who underwent a long-course of CRT and high-resolution rectal MRIs between January 2020 and April 2021. Axial T2WI was reconstructed using the conventional method (MRIconv) and DLR with two different noise reduction factors (MRIDLR30 and MRIDLR50). The signal-to-noise ratio (SNR) of the tumor was measured. Two experienced radiologists independently made a blind assessment of the complete response on MRI. The sensitivity and specificity for pCR were analyzed using a multivariable logistic regression analysis with generalized estimating equations. RESULTS: Thirty-four patients did not have a pCR whereas five (12.8%) had pCR. Compared with the SNR of MRIconv (mean ± SD, 7.94 ± 1.92), MRIDLR30 and MRIDLR50 showed higher SNR (9.44 ± 2.31 and 11.83 ± 3.07, respectively) (p < 0.001). Compared to MRIconv, MRIDLR30 and MRIDLR50 showed significantly higher specificity values (p < 0.036) while the sensitivity values were not significantly different (p > 0.301). The sensitivity and specificity for pCR were 48.9% and 80.8% for MRIconv; 48.9% and 88.2% for MRIDLR30; and 38.8% and 86.7% for MRIDLR50, respectively. CONCLUSION: DLR produced MR images with higher resolution and SNR. The specificity of MRI for identification of pCR was significantly higher with DLR than with conventional MRI.

Metabolic and magnetic resonance imaging: complementary modalities for the preoperative assessment of lateral pelvic lymph nodes in rectal cancer.

BACKGROUND: The management of lateral pelvic lymph nodes for rectal cancer is a topical and controversial issue. The aim of this study was to assess the relationship between lateral pelvic lymph node features on magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT) with oncological outcomes in patients with rectal cancer. METHODS: A retrospective analysis of 284 patients with primary locally advanced rectal cancer treated with neoadjuvant therapy and surgical resection with curative intent between January 2003 and Dec 2018 was undertaken. From this study population, a select cohort of 77 patients with abnormal lateral pelvic lymph nodes on preoperative imaging had imaging re-analysed by radiologists blinded to clinical outcomes. Pre and post neoadjuvant therapy MRI and PET-CT lateral pelvic lymph node features were correlated with oncological outcomes. RESULTS: A lateral pelvic lymph node short axis size ≥5 mm on post neoadjuvant therapy MRI was a significant predictor of worse 3-year local recurrence free survival (HR 8.35, P = 0.001). Lateral pelvic lymph node avidity on post neoadjuvant therapy PET-CT was a significant predictor of worse 3-year distant recurrence free survival (HR 5.62, P = 0.001). No correlation of oncological outcomes with overall survival was identified. CONCLUSION: Lateral pelvic lymph node imaging features on post-neoadjuvant therapy MRI and PET-CT predicted those at risk of rectal cancer recurrence. Further studies are required to confirm these findings that suggest restaging MRI and PET-CT are complementary modalities for the preoperative assessment of lateral pelvic lymph nodes in rectal cancer.