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Objective: To investigate the diagnostic performance of the apparent diffusion coefficient (ADC) derived from intratumoral and peritumoral zones for assessing pathologic prognostic factors in rectal cancer., Materials and Methods: One hundred forty-six patients with rectal cancer who underwent preoperative MRI were prospectively enrolled. Two radiologists independently placed free-hand regions of interest (ROIs) in the largest tumor cross section and three small ROIs on the peritumoral zone adjacent to the tumor contour. Maximum values of tumor ADC (ADC tmax ), minimum values of tumor ADC (ADC tmin ), mean values of tumor ADC (ADC tmean ), mean values of peritumor ADC (ADC pmean ), and ADC pmean /ADC tmean (ADC ratio) were obtained on ADC maps and correlated with prognostic factors using uni- and multivariate logistic regression, and receiver operating characteristic curve (ROC) analysis., Results: Interobserver agreement was excellent for ADC tmax and ADC tmean (intraclass correlation coefficient [ICC], 0.915-0.958), and were good for ADC tmin , ADC pmean , and ADC ratio (ICC, 0.774-0.878). The ADC ratio was significantly higher in the poor differentiation, T3-4 stage, lymph node metastasis (LNM)-positive, extranodal extension (ENE)-positive, tumor deposit (TD)-positive, and lymphovascular invasion (LVI)-positive groups than that in the well-moderate differentiation, T1-2 stage, LNM-negative, ENE-negative, TD-negative, and LVI-negative groups (p = 0.008, < 0.001, < 0.001, 0.001, < 0.001, and < 0.001, respectively). The area under the ROC curve (AUC) of the ADC ratio was the highest for assessing poor differentiation (0.700), T3-4 stage (0.707), LNM-positive (0.776), TD-positive (0.848), and LVI-positive (0.778). Both the ADC ratio (AUC = 0.677) and ADC pmean (AUC = 0.686) showed higher diagnostic performance for assessing ENE., Conclusion: The ADC ratio could provide better predictive performance for assessing preoperative prognostic factors in resectable rectal cancer., Key Points: • Both the peritumor/tumor ADC ratio and ADC pmean are correlated with important prognostic factors of resectable rectal cancer. • Both peritumor ADC and peritumor/tumor ADC ratio had higher diagnostic performance than tumor ADC for assessment of prognostic factors in resectable rectal cancer. • Peritumor/tumor ADC ratio showed the most capability for the assessment of prognostic factors in resectable rectal cancer., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

This study is to investigate optimum apparent diffusion coefficient (ADC) parameter for predicting lymphovascular invasion (LVI), lymph node metastasis (LNM) and histology type in resectable rectal cancer. 58 consecutive patients with resectable rectal cancer were retrospectively identified. The minimum, maximum, average ADC and ADC difference value were obtained on ADC maps. Maximum ADC and ADC difference value increased with the appearance of LVI (r = 0.501 and 0.495, P < 0.001, respectively) and development of N category (r = 0.615 and 0.695, P < 0.001, respectively). ADC difference value tended to rise with lower tumor differentiation (r = - 0.269, P = 0.041). ADC difference value was an independent risk factor for predicting LVI (odds ratio = 1.323; P = 0.005) and LNM (odds ratio = 1.526; P = 0.005). Maximum ADC and ADC difference value could distinguish N0 from N1 category, N0 from N1-N2, N0-N1 from N2 (all P < 0.001). Only ADC difference value could distinguish histology type (P = 0.041). ADC difference value had higher area under the receiver operating characteristic curve than maximum ADC in identifying LVI (0.828 vs 0.797), N0 from N1 category (0.947 vs 0.847), N0 from N1-N2 (0.935 vs 0.874), and N0-N1 from N2 (0.814 vs 0.770). ADC difference value may be superior to the other ADC value parameters to predict LVI, N category and histology type of resectable rectal cancer.

Aim: To determine whether and how magnetic resonance imaging (MRI)-based total liver volume (TLV) and diffusion weighted imaging (DWI) could predict liver fibrosis., Methods: Sixteen experimental mature mini-pigs (6 males, 10 females), weighing between 20.0 and 24.0 kg were prospectively used to model liver fibrosis induced by intraperitoneal injection of 40% CCl(4) dissolved in fat emulsion twice a week for 16 wk, and by feeding 40% CCl(4) mixed with maize flour twice daily for the subsequent 5 wk. All the survival animals underwent percutaneous liver biopsy and DWI using b = 300, 500 and 800 s/mm(2) followed by abdominal gadolinium-enhanced MRI at the 0, 5th, 9th, 16th and 21st weekend after beginning of the modeling. TLV was obtained on enhanced MRI, and apparent diffusion coefficient (ADC) was obtained on DWI. Hepatic tissue specimens were stained with hematoxylin and Masson's trichrome staining for staging liver fibrosis. Pathological specimens were scored using the human METAVIR classification system. Statistical analyses were performed to determine whether and how the TLV and ADC could be used to predict the stage of liver fibrosis., Results: TLV increased from stage 0 to 2 and decreased from stage 3 (r = 0.211; P < 0.001). There was a difference in TLV between stage 0-1 and 2-4 (P = 0.03) whereas no difference between stage 0-2 and 3-4 (P = 0.71). TLV could predict stage ≥ 2 [area under receiver operating characteristic curve (AUC) = 0.682]. There was a decrease in ADC values with increasing stage of fibrosis for b = 300, 500 and 800 s/mm(2) (r = -0.418, -0.535 and -0.622, respectively; all P < 0.001). Differences were found between stage 0-1 and 2-4 in ADC values for b = 300, 500 and 800 s/mm(2), and between stage 0-2 and 3-4 for b = 500 or 800 s/mm(2) (all P < 0.05). For predicting stage ≥ 2 and ≥ 3, AUC was 0.803 and 0.847 for b = 500 s/mm(2), and 0.848 and 0.887 for b = 800 s/mm(2), respectively., Conclusion: ADC for b = 500 or 800 s/mm(2) could be better than TLV and ADC for b = 300 s/mm(2) to predict fibrosis stage ≥ 2 or ≥ 3.

Aim To determine whether spleen diffusion-weighted imaging ( DWI) parameters might classify liver fibrosis stage. Methods Sixteen miniature pigs were prospectively used to model liver fibrosis, and underwent spleen DWI by using b = 300, 500 and 800 s/mm2 on 0, 5th, 9th, 16th and 21st weekend after the beginning of modeling. Signal intensity ratio of spleen to paraspinous muscles ( S/ M), spleen exponential apparent diffusion coefficient (e ADC) and apparent diffusion coefficient ( ADC) for each b-value were statistically analyzed. Results With increasing stages of fibrosis, S/ M for all b-values showed a downward trend; and spleen e ADC and ADC for b = 300 s/mm2 showed downward and upward trends, respectively (all P < 0.05). The area under the receiver-operator curve ( AUC) of spleen DWI parameters was 0.777 or more by S/ M for classifying each fibrosis stage, and 0.65 or more by e ADC and 0.648 or more by ADC for classifying stage ≥3 or cirrhosis. Among the spleen DWI parameters, S/ M for b = 300 s/mm2 was the best parameter in classifying stage 1 or more, 2 or more and 3 or more with AUC of 0.875, 0.851 and 0.843, respectively; and spleen eADC for b = 300 s/mm2 was best in classifying stage 4 with an AUC of 0.988. Conclusion Spleen DWI may be used to stage liver fibrosis. [ABSTRACT FROM AUTHOR]

Objective: To assess the role of region of interest (ROI) selection of intravoxel incoherent motion (IVIM) for predicting lymph node metastases (LNM) and tumor response after chemoradiation therapy (CRT) in locally advanced rectal cancer.Materials and Methods: Seventy-nine patients with biopsy-proven rectal adenocarcinoma who underwent pre- and post-CRT MRI and surgery were prospectively enrolled. The exclusion criteria included nonresectable and/or metastatic disease and loss of follow-up. Pathological stage was determined using ypTNM stage and tumor regression grade. Slow diffusion coefficient (D), fast diffusion coefficient (D*), perfusion-related diffusion fraction (f), apparent diffusion coefficient (ADC) and their percentage changes (Δ%) were evaluated by two readers using whole-volume, single-slice and small samples ROI methods. Risk factors including carcinoembryonic antigen, post-CRT T-staging, extramural venous invasion and IVIM parameters were evaluated through multivariate analyses. Areas under the receiver operating characteristic curves (AUCs) were calculated to evaluate diagnostic performance. Duration of follow-up was two-year. Recurrence-free survival of patients with LNM and tumor response was estimated using Kaplan-Meier analysis.Results: Interobserver agreement were good for pre- and post-CRT three ROI methods (intraclass correlation coefficient [ICC], 0.581-0.953). Whole-volume ROI-derived Δ%D was an independent risk factor for LNM, non-pathological complete response (non-pCR) and poor response (odds ratio, 0.940, 0.952, 0.805, respectively; all p < 0.001). Whole-volume ROI-derived Δ%D showed best AUC of 0.810, 0.851 and 0.903 for LNM, non-pCR and poor response (cutoff value, 31.8%, 54.5%, 52.8%, respectively). Patients with post-CRT LNM showed reduction in 2-year recurrence-free survival (hazard ratio, 3.253).Conclusions: Whole-volume ROI-derived Δ%D provided high diagnostic performance for evaluating post-CRT LNM and tumor response. Patients with post-CRT LNM showed earlier recurrence. [ABSTRACT FROM AUTHOR]