Purpose of the study. To study the patterns of forming an MRI picture of a complete pathological morphological response (pCR) of colorectal cancer a er neoadjuvant chemoradia on therapy (NHLT) based on comparisons with the pathomorphological picture. Patients and methods. Among 130 patients with locally advanced colorectal cancer who received a combined treatment with NHL at A. Tsyb MRRC clinic — a Branch of HMRRC of the Ministry of Health of the Russian Federation within the period 2012–2017 thirteen patients were selected for the study, in whom pCR was achieved, according to the pathological analysis of surgical specimen. MRI was performed on all patients before the NHLT and atier the end (atier 6–10 weeks) of treatment. We analyzed the MRI fi ndings from case histories (prospective assessment) on degree of tumor regression (mrTRG) using a fi ve-point grading scale. Ten of these patients had MRI examinations available for re-review (retrospective assessment), which allowed for a qualitate ve assessment of the signal intensity in T2 mode on a nominal scale, according to which low, medium, moderately elevated and high MR signals were discerned; signal localization was determined relative to the intestinal lumen with conditional selection of the inner and outer layer of the wall, and the outer contour was charactezied (smooth or uneven due to hypointense spicules). The obtained data on the localization of the MR signal of varying intensity were compared with the data of the pathological description of the operating drugs.Results. A prospective MRI assessment of pCR in 77% of cases corresponded to TRG2 and in 92% — y N0. Macroscopically, the pCR in all patients had an appearance of an ulcerative defect of the intestinal wall, to which on T2-WI in 80% of cases corresponded to a moderately elevated MR signal from the inside of the wall, due to necroti c changes and granulations, and in 100% of cases — a low MR signal from the outer layer of the intestinal wall, caused by a more mature connective tissue, the outer contour in 50% of cases was tight due to the desmoplastic reaction; hypo-intensive inclusions corresponded to lime deposits, and “mucous lakes” — inclusions with high signal intensity and clear contours.Conclusion The features of forming MRI picture of the pCR are due to a range of radiation pathomorphosis manifestations, including destructive, regenera ve and infl ammatory processes in the tumor stroma.
Background. Evaluation of the therapeutic effect of neoadjuvant chemoradiotherapy (nCRT) for rectal cancer (RC) is of prognostic value and allows to individually plan the type and extent of further surgical intervention. One of the most promising methods of MRI evaluation is magnetic resonance tumour regression grade (mrTRG) system. However, the reliability and safety of this method must be confirmed by the results of clinical trials and practical application.Objective: to analyze our experience in the prospective use of mrTRG system and evaluate the additional contribution of diffusion-weighted images (DWI) to its diagnostic efficiency.Material and methods. The mrTRG values were determined in 125 (including 30 with DWI) patients with locally advanced RC who received combined treatment with nCRT in Tsyb Medical Radiological Research Centre from 2015 to 2019. The obtained data were compared with the modified pathologic response based on Lushnikov’s definition, and the diagnostic parameters of differentiation of patients responding and nonresponding to nCRT were calculated.Results. When the mrTRG system was used without DWI, the following sensitivity and specificity values as well as positive and negative predictive values were obtained: 75%, 60%, 70% and 67%, respectively, with DWI – 87%, 87%, 87% and 87%, respectively.Conclusion. A prospective evaluation of the result of nCRT using the mrTRG system has moderate accuracy for stratification of patients responding and non-responding to nCRT, which requires the use of additional criteria for MRI scores to select patients who may receive less aggressive surgical treatment. Despite the small number of patients with DWI, we obtained higher values of the diagnostic parameters. In this regard, we consider it appropriate to use DWI when assessing the treatment response.
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