Research Presentation Session: Abdominal Viscera & GI Tract

RPS 401 - Diagnosis and response assessment in colorectal cancer

February 28, 13:00 - 14:30 CET

7 min
Value of Iodine uptake derived from DECT in differentiating malignant from benign colorectal wall thickening
Lucien Widmer, Villars-Sur-Glâne / Switzerland
Author Block: L. Widmer1, F. Cherbanyk1, H. Thoeny1, S. Malekzadehlashkariani2; 1Fribourg/CH, 2Sion/CH
Purpose: The aim of this study was to assess the performance of iodine uptake derived from Dual-energy computed tomography (DECT) in differentiating malignant from benign colorectal wall thickening.
Methods or Background: DECT is widely used to characterise and differentiate tumours. However, data regarding its diagnostic performance for the characterisation of colorectal tumours are limited. In this single-centre IRB-approved study, 50 consecutive patients with both histopathology-proven colorectal adenocarcinoma and benign colon wall pseudo-thickening were prospectively enrolled. Two radiologists quantitatively analysed the iodine uptake of the tumors and iodine ratios as well as density measurements in Hounsfield units (HU) from portal venous phase DECT. Paired t-test and predictive power score were used to compare variables of malignant and benign wall thickening. A priori statistical power analysis using G*Power estimated that 45 patients were necessary to reach a 95% statistical power for a one-sided paired t-test with a medium effect size and an alpha of 0.05.
Results or Findings: Significantly greater iodine uptakes were found in tumours than in benign wall pseudo-thickenings (medium to strong predictive power, delta = 0.13, t(49) = 7.3, p < 0.001, pps = 0.64). There were no equivalence between the tumours and the benign wall pseudo-thickenings (delta = 0.17, t(49) = 6.4, p = 1), but significantly greater HU values in tumours compared to benign wall pseudo-thickenings (strong predictive power, t(49) = 15.8, p < 0.001, pps = 0.79).
Conclusion: DECT demonstrated a significant difference in HU and iodine uptake in malignant colorectal tumours in comparison to benign colorectal wall pseudo-thickening. However, this study surprisingly shows that HU is a variable of better value than iodine uptake in discriminating a tumour from a non-tumour pseudo-thickening.
Limitations: Single-centre study and small sample size; adenocarcinoma as only histopathological subtype; manual delineation of ROIs limit the scope of this study.
Funding for this study: No funding was obtained for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: CER-VD, swissethics approved this study.
7 min
Performance of CT in the locoregional staging of non-rectal colon cancer: detailed radiology-pathology correlation with a special emphasis on tumour deposits and extramural venous invasion
Duygu Karahacıoğlu, Istanbul / Turkey
Author Block: D. Karahacıoğlu, O. C. Taskin, A. Armutlu, B. Saka, R. Esmer, D. Bugra, E. Balik, V. Adsay, B. Gurses; Istanbul/TR
Purpose: The purpose of this study was to investigate the performance of CT in detecting the diagnostic and prognostic characteristics (established in rectal adenocarcinomas) in non-rectal colon malignancies via close radiologic and pathologic correlation in order to improve patient care.
Methods or Background: CT and pathology data from 137 resected colonic adenocarcinoma cases were reviewed for prognostic parameters by dedicated radiologists and pathologists whose primary practice is GI cancers. Discrepant cases were re-evaluated together with correlation of radiologic-gross photographs and microscopic findings.
Results or Findings: For T-stage, overall CT tended to understage (in 12.4% of cases), performed better in left versus right colon, with the lowest performance observed in transverse colon, and the highest rate of misstaging at sigmoid. The sensitivity, specificity, and accuracy of CT in the detection of EMVI were 58,5 %, 82,1 %, 73 % (which was slightly better for high-load EMVI compared to low-load). These figures for TDs were 57,9 %, 92,4 %, 87,6 and for LNs, 44.7%, 72.7%, and 63.5%. In 13 patients with discrepancies, on-site correlation resulted in modification of the initial radiology or pathology findings.
Conclusion: The criteria increasingly employed for rectal cancers and were elucidated by careful pathologic radiologic correlation in our studies demonstrate that CT can be more effectively used in prognostication of colon cancers. CT appears to be more applicable in left colon, although mis-stagings are most common in the sigmoid, for which more non-committal reporting may be necessary in uncertain cases. CT is highly effective in detection of TDs and EMVI (especially high-load), but less so for LNs. TD and EMVI should be considered for incorporation into routine reporting CT proformas for colon cancer.
Limitations: The major limitation is the absence of specimen radiology, which prevents the correlation of LN/TD on a case-by-case basis.
Funding for this study: No funding was recieved for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the IRB number: 2022.092.IRB1.038
7 min
Preoperative evaluating peritoneal cancer index in peritoneal metastatic colon cancer patients using CT-based deep-learning model
Shaoting Zhang, Jinan / China
Author Block: S. Zhang1, F. Shen2, C. Shao2; 1Jinan/CN, 2Shanghai/CN
Purpose: This study aimed to build a convolution neural network to automatically segment the colon cancer lesion and evaluate peritoneal cancer index (PCI) in peritoneal metastasis (PM) cases based on preoperative CT scans.
Methods or Background: A total of 177 consecutive colon cancer patients with preoperative abdominopelvic CT scans and PM administered exploratory laparotomy were retrospectively analysed. Surgical PCIs (sPCIs) were confirmed by the surgery team, and CT-PCI scores were assessed by radiologists. Totally 90 cases were assigned to training set. Then, 87 cases were enrolled as test set. Initially, we utilised nn-UNet to build an automatic segmentation model based on CT scans at portal venous phase. Secondly, we constructed deep learning model (DL-Model) to assess sPCIs. The performances in distinguishing between low-sPCI (≤ 20) and high-sPCI (> 20) cases were also assessed by receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA).
Results or Findings: The automatic segmentation model showed excellent performance. The DL-Model had higher classification performance than the subjective evaluation in all datasets (AUCs were 0.867 and 0.830 in training and test sets, vs 0.767 and 0.694, respectively). The usefulness of the proposed DL-Model was confirmed by DCA.
Conclusion: This study showed that the DL-Model based on abdominopelvic CT scans were useful for preoperative detecting PCI in colon cancer patients with PM, especially showed increased diagnostic performance than subjective CT-PCI.
Limitations: It is unclear whether our findings would apply to the lesion with neoadjuvant treatment, which needs further research.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: Committee on Medical Research Ethics of Changhai Hospital approved this study.
7 min
Early regression index (ERI) on MR images predicts complete responders after neo-adjuvant chemo-radiotherapy
Martina Mori, Milan / Italy
Author Block: C. Fiorino, D. Palumbo, M. Mori, G. Palazzo, A. Pellegrini, A. Damascelli, S. Steidler, A. Del Vecchio, F. De Cobelli; Milan/IT
Purpose: The early regression index (ERI) resulted to predict treatment response in rectal cancer patients. Aim of the current study was to prospectively assess tumour response to neo-adjuvant chemo-radiotherapy (nCRT) of locally advanced oesophageal cancer using ERI, based on MRI.
Methods or Background: From January 2020 to May 2023, 30 patients with oesophageal cancer were enrolled in a single arm prospective study (ESCAPE). Patients were scanned with PET-MRI at three time points: (i) before nCRT (tpre); (ii) mid-radiotherapy, tmid; (iii) after nCRT, 8-12 weeks before surgery (tpost); nCRT delivered 41.4Gy/23fr with concurrent carboplatin and paclitaxel. For patients that skipped surgery, complete clinical response (cCR) was assessed if patients showed no local relapse after one year; patients with pathological complete response (pCR) or with cCR were considered as complete responders (pCR+cCR). Segmentations of GTV volumes were performed by two observers (Vpre, Vmid, Vpost) on T2w MRI: ERI and other volume regression parameters at tmid and tpost were tested as predictors of pCR+cCR.
Results or Findings: At the time of the analysis complete data of 25 patients were available: 3/25 with complete response at imaging refused surgery and 2/3 were cCR; in total, 10/25 patients showed pCR+cCR (pCR=8/22). Both ERImid and ERIpost identified pCR+cCR patients, with ERImid showing better performance (AUC:0.78, p=0.014). A logistic model combining ERImid and Vpre improved performances (AUC:0.93, p<0.0001). Inter-observer variability in contouring GTV did not affect the results.
Conclusion: Despite the limited numbers, interim analysis of ESCAPE study suggests ERI as a robust predictor of complete response after nCRT for esophageal cancer. Further validation on larger populations is warranted.
Limitations: Interruptions due to Covid-19 pandemia caused the downsizing of the sample size.
Funding for this study: The study was supported by AIRC (Italian Association for Cancer Research) under Investigator Grant – IG 2019 – ID 23015 project.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study received institutional review board approval and written informed consent was obtained from all participants.
7 min
Role of IVIM MRI in response assessment in colorectal carcinoma
Stuti Chandola, New Delhi / India
Author Block: C. J. Das, S. Chandola, A. Soni; New Delhi/IN
Purpose: The aim of this study was to. assess the usefulness and performance of Diffusion-weighted imaging (DWI) with IVIM- DKI for assessing post chemotherapy (CT)/Chemo and Radiotherapy (CTRT) response in colorectal carcinoma and compare with PET/CT parameters
Methods or Background: Forty patients with rectosigmoid cancer underwent baseline staging multiparametric MRI and 18-FDG PET/CT and follow-up with both scans post chemo radiotherapy. Quantitative diffusion, IVIM and DKI parameters, viz. apparent (ADC) and molecular (D) diffusion coefficient, perfusion coefficient (f), and kurtosis (K) were measured from non-necrotic areas and semi-quantitative PET parameters including SUV max, SUV ratio, Metabolic tumour volume (MTV), and total lesion glycolysis (TLG) were derived from the PET/CT images; and correlated with the patient’s response keeping RECIST 1.1 criteria as the gold standard.
Results or Findings: A statistically significant increase in D and ADC with a decline in K was noted after therapy in all patients. No significant difference was seen among the percentage change in the parameters observed post-therapy among the responders and non-responders. Both the responders as well as non-responders depicted a statistically significant increase in D and ADC, and a significant decline in K values post-therapy. Among 17 patients with follow-up PET/CT imaging, a significant decline in all parameters of the primary lesion was seen post-therapy. Responders (n=12) showed a significant decline in all parameters from baseline after therapy, whereas non-responders did not show any such decline. Post-therapy MTV, followed by TLG were found to have strongest correlation with a positive response, with AUCs of 0.933 and 0.900 on receiver operator curves.
Conclusion: 18-FDG PET/CT is the more accurate single modality for assessing both response as well as tumour burden post therapy, while ADC and D derived from DWI and IVIM respectively are useful adjuncts for assessment of response.
Limitations: No information provided by the submitted.
Funding for this study: No funding was provided for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The ethics committee notification can be found under the number ID - IEC PG-621/25.11.20, RT-06/23.12.2020.
7 min
Can MRI accurately assess the TN staging of rectal cancer patients with local regrowth during watchful waiting?
Xinde Ou, Amsterdam / Netherlands
Author Block: X. Ou, B. M. Geubels, D. M. J. Lambregts, B. Grotenhuis, G. L. Beets, R. G. H. Beets-Tan, M. Maas; Amsterdam/NL
Purpose: Local regrowth during watchful waiting occurs in +/-25% of patients. Salvage surgery is possible in the vast majority. MRI is used for regrowth staging, but its accuracy is unknown. The aim is to evaluate the accuracy of MRI for preoperative TN-staging of rectal cancer patients with local regrowth during organ preservation.
Methods or Background: Rectal cancer patients identified with local regrowth during watchful waiting all underwent salvage surgery (TME or local excision). Patients who underwent local excision as salvage surgery were excluded from N-status analyses if their follow-up after local excision was < 24 months. An expert radiologist scored the ymrTN-stage on pre-surgery MRIs. The ymrT and ymrN-stages were compared with final ypT and ypN-stages at histopathology. For analysis, T0, T1 and T2 were combined as T0-2 and T3 and T4 combined as T3-4; N1 and N2 were combined as N+. Diagnostic performance (accuracy, sensitivity, specificity) were calculated.
Results or Findings: Among these patients, 26 had ypT-stage available (17 ypT0-2, 9 ypT3-4) and 22 had ypN-stage available (15 ypN0, 7ypN+). The MRI-to-surgery interval ranged from 2 to 19 weeks (median: 7 weeks). 20 had luminal regrowth, one had nodal regrowth, and six had both. Accuracy, sensitivity and specificity for ypT-staging were 81%, 76% and 89%. Overstaging occurred in 15%. Accuracy, sensitivity and specificity for ypN-staging were 82%, 80% and 82%. Understaging occurred in 14%.
Conclusion: MRI can accurately stage local regrowth during watchful waiting before surgery. In ypT-staging, overstaging is common, while ypN-staging is more prone to understaging.
Limitations: Multiple readers need to be included to assess the interobserver agreement and evaluate the impact of radiologists' experience on ymrTN-staging accuracy. Sample size is rather small. Selection bias needs to be considered for the highly selected group.
Funding for this study: Not applicable for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: Not applicable for this study.
7 min
The involvement of mesorectal fascia by tumour deposits and extramural venous invasion predicts poor overall survival in locally advanced rectal cancer
Yaru Feng, Shanghai / China
Author Block: Y. Feng, T. Tong; Shanghai/CN
Purpose: Mesorectal fascia (MRF) involvement serves as an adverse prognostic indicator for locally advanced rectal cancer (LARC). However, prognoses among MRF+ patients vary. This study aims to further classify MRF involvement in MRF+ cases and investigate its prognostic implications.
Methods or Background: We conducted a retrospective analysis of data from LARC patients who were evaluated MRF+ and underwent surgery after neoadjuvant chemoradiotherapy. Patients were categorised into four groups based on MRF involvement: MRF+ (Tumour) vs MRF+ (Non-tumour), MRF+ (Extramural venous invasion; EMVI) vs MRF+ (Non-EMVI), MRF+ (lymph node; LN) vs MRF+ (Non-LN), and MRF+ (Tumour deposits; TDs) vs MRF+ (Non-TDs). Survival curves were generated using the Kaplan-Meier (K-M) method, and differences in overall survival (OS) were assessed using the log-rank test. Prognostic factors were evaluated through multivariate Cox proportional hazards models.
Results or Findings: A total of 400 MRF+ LARC patients were included in the study. The occurrence of MRF+ (Tumour), MRF+ (TDs), and MRF+ (EMVI) was higher in patients aged ≥60 years. In K-M survival analysis, both MRF+ (TDs) and MRF+ (EMVI) cases were associated with significantly worse OS compared to MRF+(non-TDs) and MRF+ (non-EMVI). Conversely, there were no significant differences in OS between MRF+ (Tumour) and MRF+ (LN) cases and MRF+ (Non-tumour) and MRF+ (non-LN). In the multivariate COX regression analysis, MRF+ (TDs) demonstrated a significant association with OS (HR 1.744; 95% CI, 1.064-2.860). Similarly, MRF+ (EMVI) displayed a significant correlation OS (HR 1.886; 95% CI, 1.076-3.306). Conversely, there were no significant associations observed between MRF+ (Tumour) or MRF+ (LN) and OS.
Conclusion: MRF+ (TDs) and MRF+ (EMVI) independently indicated higher risks for adverse prognosis in MRF+ LARC patients, providing valuable insights for treatment and follow-up strategies.
Limitations: This was a retrospective and single centre study.
Funding for this study: No funding was obtained for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This research was approved ethically.
7 min
Performance of dual-layer spectrum CT virtual monoenergetic images to assess early rectal adenocarcinoma T-stage: comparison with MR
Ziqi Jia, Guangzhou / China
Author Block: Z. Jia, W. j. Yuan, X. M. Liu, H. Zhang, J. Dai, L. Guo, W. C. Chen, X. Liu; Guang Zhou/CN
Purpose: Dual-layer spectrum CT (DLSCT) can provide information about material decomposition and improve lesion visualization that may be useful to assess preoperative T-stage in early rectal carcinoma (ERC). This study aimed to investigate the image quality of virtual monoenergetic images (VMI) and conventional polyenergetic image (PEI) from DLSCT, and compare the performance with MR in assessing preoperative T-stage for early rectal adenocarcinoma (ERA).
Methods or Background: This retrospective study included 67 ERA patients (mean age 62±11.1 years) who underwent DLSCT and MR examination. VMI 40-200 keV and poly energetic image (PEI) were reconstructed. The image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and tumour contrast of different energy levels were calculated and compared, respectively. Two radiologists independently assess the image quality of the VMIs and PEI using five-point scales. The diagnostic accuracies of DLSCT and HR-MRI for ERA T-staging were evaluated and compared.
Results or Findings: The maximum noise was observed at VMI 40 keV, and noise at VMI 40-200keV in the arterial and venous phases showed no statistically significant difference (all p>0.05). The highest SNR and CNR were obtained at VMI 40 keV, significantly greater than other energy levels and PEI (all p<0.05). Tumour contrast was more evident than PEI at 40-100keV in the arterial phase and at 40keV in the venous phase (all p <0.05). When compared with PEI, VMI 40keV yielded the highest scores for overall image quality, tumour visibility, and tumor margin delineation, especially in the venous phase (p<0.05). The overall diagnostic accuracy of DLSCT and HR-MRI for T-stage was 65.67% and 71.74% and showed no statistically significant difference (p>0.05).
Conclusion: VMI 40keV provides the best image quality and improves the diagnostic confidence for ERA staging.
Limitations: Not applicable for this study.
Funding for this study: This work was supported by Guangzhou Basic and Applied Basic Research Foundation 2023A03J024, National Nature Science of Foundation of China [Grant No.82202259] and the Youth Talent Project of The Second Affiliated Hospital of Guangzhou University of Chinese Medicine(ZY2022YL05)
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study received institutional review board approval and written informed consent was obtained from all participants

This session will not be streamed, nor will it be available on-demand!