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.
The study objective was to investigate the role of 18 F-fluorodeoxyglucose (18 F-FDG) positron emission tomography combined with computed tomography (PET-CT) as an indirect determination of the differentiation status of metastases and for the prediction of radioactive iodine (RAI) therapy response in patients with metastatic differentiated thyroid cancer.Materials and methods. The 40 metastatic differentiated thyroid cancer patients were enrolled in the study that underwent both post-therapeutic radioiodine scan and PET-CT at the same period.Results. The study found that 12 (30 %) patients responded to RAI therapy. The remaining 28 (70 %) patients not responded to RAI therapy showed stabilization or progression. The accumulation of radioiodine by metastases positively correlated with the total response rate, while the 18 F-FDG avidity is negative. Significant direct correlation with response rate was observed in the group with only radioiodine uptake. However, this correlation was not observed in the patients with both tracers uptake. The patients with 18 F-FDG-positive metastases showed poor response to RAI therapy, regardless of the degree of radioiodine uptake.Conclusion. The 18 F-FDG uptake by metastases is a predictor of a poor response to RAI therapy, even in the presence of RAI uptake. The use of 18 F-FDG PET-CT in patients with metastatic differentiated thyroid cancer can be recommended at the beginning of RAI therapy to clarify the prognosis and provide a personalized approach to the treatment and observation of the most difficult category of patients.
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