Diffusion tensor field estimation based on 3D U-Net and diffusion tensor imaging model constraint / 南方医科大学学报

OBJECTIVE@#To propose a diffusion tensor field estimation network based on 3D U-Net and diffusion tensor imaging (DTI) model constraint (3D DTI-Unet) to accurately estimate DTI quantification parameters from a small number of diffusion-weighted (DW) images with a low signal-to-noise ratio.@*METHODS@#The input of 3D DTI-Unet was noisy diffusion magnetic resonance imaging (dMRI) data containing one non-DW image and 6 DW images with different diffusion coding directions. The noise-reduced non-DW image and accurate diffusion tensor field were predicted through 3D U-Net. The dMRI data were reconstructed using the DTI model and compared with the true value of dMRI data to optimize the network and ensure the consistency of the dMRI data with the physical model of the diffusion tensor field. We compared 3D DTI-Unet with two DW image denoising algorithms (MP-PCA and GL-HOSVD) to verify the effect of the proposed method.@*RESULTS@#The proposed method was better than MP-PCA and GL-HOSVD in terms of quantitative results and visual evaluation of DW images, diffusion tensor field and DTI quantification parameters.@*CONCLUSION@#The proposed method can obtain accurate DTI quantification parameters from one non-DW image and 6 DW images to reduce image acquisition time and improve the reliability of quantitative diagnosis.

Cerebral ischemic injury after transcatheter aortic valve replacement in patients with pure aortic regurgitation / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Considering the surgical risk stratification for patients with severe calcific aortic stenosis (AS), transcatheter aortic valve replacement (TAVR) is a reliable alternative to surgical aortic valve replacement (SAVR) (Fan et al., 2020, 2021; Lee et al., 2021). Despite the favorable clinical benefits of TAVR, stroke remains a dreaded perioperative complication (Auffret et al., 2016; Kapadia et al., 2016; Kleiman et al., 2016; Huded et al., 2019). Ischemic overt stroke, identified in 1.4% to 4.3% of patients in TAVR clinical practice, has been associated with prolonged disability and increased mortality (Auffret et al., 2016; Kapadia et al., 2016; Levi et al., 2022). The prevalence of hyperintensity cerebral ischemic lesions detected by diffusion-weighted magnetic resonance imaging (DW-MRI) was reported to be about 80%, which is associated with impaired neurocognitive function and vascular dementia (Vermeer et al., 2003; Barber et al., 2008; Kahlert et al., 2010).

Comparison of ZOOMit-DWI sequence and conventional DWI sequence in endometrial cancer / 中南大学学报(医学版)

OBJECTIVES@#Magnetic resonance diffusion-weighted imaging (DWI) has important clinical value in diagnosis and curative effect evaluation on endometrial carcinoma. How to improve the detection rate of endometrial small lesions by DWI is the research focus of MRI technology. This study aims to analyze the image quality of small field MRI ZOOMit-DWI sequence and conventional single-shot echo-planar imaging (SS-EPI) DWI sequence in the scanning of endometrial carcinoma, and to explore the clinical value of ZOOMit-DWI sequence.@*METHODS@#A total of 37 patients with endometrial carcinoma diagnosed by operation and pathology in the Second Xiangya Hospital of Central South University from July 2019 to May 2021 were collected. All patients were scanned with MRI ZOOMit-DWI sequence and SS-EPI DWI sequence before operation. Two radiologists subjectively evaluated the anatomical details, artifacts, geometric deformation and focus definition of the 2 groups of DWI images. At the same time, the signal intensity were measured and the signal-to-noise ratio (SNR), contrast to noise ratio (CNR), and apparent diffusion coefficient (ADC) of the 2 DWI sequences were calculated for objective evaluation. The differences of subjective score, objective score and ADC value of the 2 DWI sequences were analyzed.@*RESULTS@#The SNR of the ZOOMit-DWI group was significantly higher than that of the SS-EPI DWI group (301.96±141.85 vs 94.66±41.26), and the CNR of the ZOOMit-DWI group was significantly higher than that of the SS-EPI DWI group (185.05±105.45 vs 57.91±31.54, P<0.05). There was no significant difference in noise standard deviation between the ZOOMit-DWI group and the SS-EPI DWI group (P>0.05). The subjective score of anatomical detail and focus definition in the ZOOMit-DWI group was significantly higher than that of the SS-EPI DWI group (both P<0.05). The subjective score of artifacts and geometric deformation of ZOOMit-DWI group was significantly lower than that of the SS-EPI DWI group (both P<0.05). ADC had no significant difference between the ZOOMit-DWI group and the SS-EPI DWI group (P>0.05).@*CONCLUSIONS@#The image quality of ZOOMit-DWI is significantly higher than that of conventional SS-EPI DWI. In the MRI DWI examination of endometrial carcinoma, ZOOMit-DWI can effectively reduce the geometric deformation and artifacts of the image, which is more conducive to clinical diagnosis and treatment.

Magnetic resonance differential analysis for different hormone receptor expression status in HER-2-positive breast cancer / 中南大学学报(医学版)

OBJECTIVES@#Currently, it is difficult to assess the expression status of hormone receptor (HR) in breast malignant tumors with human epidermal growth factor receptor 2 (HER-2)-positive in the early preoperative stage, and it is difficult to predict whether it is non-invasively. This study aims to explore the value of MRI on the different HR expression status (HR+/HR-) in HER-2 positive breast cancer.@*METHODS@#Thirty patients with HR+ HER-2-positive breast cancer (HR+ group) and 23 patients with HR-HER-2-positive breast cancer (HR- group) from the First Hospital of Hunan University of Traditional Chinese Medicine between January 7, 2015 and November 26, 2021 were selected as subjects, and all the patients were examined by MRI and all were confirmed by surgery or pathological biopsy puncture. The immunohistochemical staining results were used as the gold standard to analyze the basic clinical conditions, peri-lesion conditions and MRI sign characteristics in the 2 groups.@*RESULTS@#There were all significant differences in terms of mass margins, internal reinforcement features, and apparent diffusion coefficient (ADC) values between the HR+ group and the HR- group (all P<0.05). The logistic multivariate regression model showed that: when the lesion presented as a mass-type breast cancer on MRI, the internal enhancement features of the lesion were an independent predictor for differentiation in the 2 types of breast cancer [odds ratio (OR)=5.95, 95% CI: 1.223 to 28.951, P<0.05], and the mass margin (OR=0.386, 95% CI: 0.137 to 1.082, P>0.05) and ADC value (OR=0.234, 95% CI: 0.001 to 105.293, P>0.05) were not the independent predictors in distinguishing the 2 types of breast cancer.@*CONCLUSIONS@#Multiparametric MRI has good diagnostic value for HR expression status in HER-2-positive breast cancer. Combined logistic regression analysis to construct a predictive model may be helpful to the identical diagnosis.

Radiomics based on biparametric MRI for the detection of significant residual prostate cancer after androgen deprivation therapy: using whole-mount histopathology as reference standard / 亚洲男科学杂志(英文版)

We aimed to study radiomics approach based on biparametric magnetic resonance imaging (MRI) for determining significant residual cancer after androgen deprivation therapy (ADT). Ninety-two post-ADT prostate cancer patients underwent MRI before prostatectomy (62 with significant residual disease and 30 with complete response or minimum residual disease [CR/MRD]). Totally, 100 significant residual, 52 CR/MRD lesions, and 70 benign tissues were selected according to pathology. First, 381 radiomics features were extracted from T2-weighted imaging, diffusion-weighted imaging, and apparent diffusion coefficient (ADC) maps. Optimal features were selected using a support vector machine with a recursive feature elimination algorithm (SVM-RFE). Then, ADC values of significant residual, CR/MRD lesions, and benign tissues were compared by one-way analysis of variance. Logistic regression was used to construct models with SVM features to differentiate between each pair of tissues. Third, the efficiencies of ADC value and radiomics models for differentiating the three tissues were assessed by area under receiver operating characteristic curve (AUC). The ADC value (mean ± standard deviation [s.d.]) of significant residual lesions ([1.10 ± 0.02] × 10-3 mm2 s-1) was significantly lower than that of CR/MRD ([1.17 ± 0.02] × 10-3 mm2 s-1), which was significantly lower than that of benign tissues ([1.30 ± 0.02] × 10-3 mm2 s-1; both P < 0.05). The SVM feature models were comparable to ADC value in distinguishing CR/MRD from benign tissue (AUC: 0.766 vs 0.792) and distinguishing residual from benign tissue (AUC: 0.825 vs 0.835) (both P > 0.05), but superior to ADC value in differentiating significant residual from CR/MRD (AUC: 0.748 vs 0.558; P = 0.041). Radiomics approach with biparametric MRI could promote the detection of significant residual prostate cancer after ADT.

Research progress on head imaging features of carbon monoxide poisoning and delayed encephalopathy / 中华劳动卫生职业病杂志

Acute carbon monoxide poisoning and its delayed encephalopathy have obvious damage to the central nervous system. There are different neuroimaging changes in different stages of the disease, and they are relatively specific. This article reviews the clinical research progress on the imaging changes of carbon monoxide poisoning and delayed encephalopathy, including computed tomography (CT) , conventional magnetic resonance imaging (MRI) , diffusion weighted imaging (DWI) , diffusion tensor imaging (DTI) , diffusion kurtosis imaging (DKI) , magnetic resonance spectroscopy (MRS) and other imaging changes reflecting the function and metabolic state of the brain tissue.

Histogram analysis of based on two-dimensional ultrasound images to differentiate medullary thyroid carcinoma and thyroid adenoma / 中华肿瘤杂志

Objective: To investigate the feasibility and value of histogram analysis based on two-dimensional gray-scale ultrasonography in the differential diagnosis of medullary thyroid carcinoma (MTC) and thyroid adenoma (TA). Methods: The preoperative ultrasound images of 86 newly diagnosed MTC patients and 100 TA patients treated in the Cancer Hospital of Chinese Academy of Medical Sciences from January 2015 to October 2021 were collected. Histograms were performed based on the regions of interest (ROIs) delineated manually by two radiologists, thereafter, mean, variance, skewness, kurtosis, percentiles (1st, 10th, 50th, 90th, 99th) were generated. The histogram parameters between the MTC group and the TA group were compared, and the independent predictors were screened by multivariate logistic regression analysis. Receiver operating characteristic (ROC) analysis was used to compare the individual diagnostic efficacy and joint diagnostic efficacy of independent predictors. Results: Multivariate regression analysis showed that mean, skewness, kurtosis and 50th percentile were independent factors. The skewness and kurtosis in the MTC group were significantly higher than those in the TA group, and the mean and 50th percentile were significantly lower than those in the TA group. The area under the individual ROC curve of mean, skewness, kurtosis and 50th percentile is 0.654-0.778. The area under the combined ROC curve is 0.826. Conclusion: Histogram analysis based on two-dimensional gray-scale ultrasonography is a promising tool to distinguish MTC from TA, in which the joint diagnosis value of mean, skewness, kurtosis and 50th percentile is the highest.

Magnetic resonance imaging changes and clinical features of reversible posterior leukoencephalopathy syndrome / 中南大学学报(医学版)

OBJECTIVES@#Reversible posterior leukoencephalopathy syndrome (RPLS) is a rare clinical imaging syndrome. The causes of RPLS are complex and diverse, the pathogenesis is not yet clear. The onset is urgent and the onset age span is large, ranging from children to the elderly. The clinical symptoms of RPLS have no significant specificity, which can be manifested as headache, blurred vision, disturbance of consciousness or seizures. Clinicians have little knowledge on the disease, which may lead to misdiagnosis or missed diagnosis. This study aims to analyze and summarize the MRI changes and clinical characteristics regarding RPLS patients, so as to provide basis for rapid diagnosis and timely intervention for this disease.@*METHODS@#The clinical data and complete imaging data of 77 patients with RPLS diagnosed in Xiangya Hospital of Central South University from January 2012 to March 2021 were retrospectively collected. The main image data include T1 weighted imaging (T1WI), T2 weighted imaging (T2WI), T2 liquid attenuation inversion recovery (T2-FLAIR), diffusion weighted imaging (DWI) (b value=1 000×10-6 mm2/s), and apparent diffusion coefficient (ADC). The case group included 63 patients who underwent DWI examination, and 71 normal controls matched in age and sex. The characteristics of patients' magnetic resonance signals and the ADC value of 19 regions of interest (ROI) were analyzed. The differences in bilateral ADC value in the case group, the difference of ADC value between the case group and the normal control group, and the difference of ADC value in the case group before and after treatment were compared.@*RESULTS@#Compared with the normal control group, the ADC value of the right frontal lobe, bilateral parietal lobe, bilateral thalamus, bilateral head of caudate nucleus, left lenticular nucleus, right internal capsule, bilateral temporal lobe and pons in the case group were significantly higher (all P<0.01). There was no significant difference in ADC value of bilateral sides of the case group and before and after treatment in the case group (all P>0.01). The lesions of RPLS were widely distributed and multiple, usually high signal in the posterior parieto temporo occipital lobe or pons of the brain, and involved the cortex and subcortical white matter. Most of them were bilateral, but not completely symmetrical.@*CONCLUSIONS@#The imaging manifestations of RPLS and the occurrence and development of clinical symptoms are basically synchronous. The imaging manifestations are specific. Magnetic resonance imaging can show the range of involvement of RPLS. ADC value can provide information on the severity of the disease and predict the prognosis. There are few reversible diseases. It is very important to fully understand and timely diagnose the disease.

Fiber direction estimation using constrained spherical deconvolution based on multi-model response function / 生物医学工程学杂志

Constrained spherical deconvolution can quantify white matter fiber orientation distribution information from diffusion magnetic resonance imaging data. But this method is only applicable to single shell diffusion magnetic resonance imaging data and will provide wrong fiber orientation information in white matter tissue which contains isotropic diffusion signals. To solve these problems, this paper proposes a constrained spherical deconvolution method based on multi-model response function. Multi-shell data can improve the stability of fiber orientation, and multi-model response function can attenuate isotropic diffusion signals in white matter, providing more accurate fiber orientation information. Synthetic data and real brain data from public database were used to verify the effectiveness of this algorithm. The results demonstrate that the proposed algorithm can attenuate isotropic diffusion signals in white matter and overcome the influence of partial volume effect on fiber direction estimation, thus estimate fiber direction more accurately. The reconstructed fiber direction distribution is stable, the false peaks are less, and the recognition ability of cross fiber is stronger, which lays a foundation for the further research of fiber bundle tracking technology.

Imaging features of 10 patients with toxic encephalopathy caused by diquat / 中华劳动卫生职业病杂志

Objective: To explore the CT and MRI imaging findings of diquat toxic encephalopathy. Methods: CT and MRI imaging features of 10 patients with diquat poisoning encephalopathy who had been clinically diagnosed were retrospectively reviewed. Results: CT was performed in all 10 patients, and MRI was performed in 8 patients. In 10 patients, 7 had positive signs on CT, and 8 patients with MRI examination had abnormal changes in the images. The main CT findings were symmetrical hypodensity in bilateral cerebellar hemisphere, brainstem, thalamus and basal ganglia, and swelling of brain tissue. The main MRI findings were symmetrical lesions and brain edema in the deep nuclei of cerebellar hemisphere, brainstem, thalamus and basal ganglia, low signal on T1WI, high signal on T2WI and T2-FLAIR, and cytotoxic edema on diffusion weighted imaging (DWI) . On review after treatment, both CT and MRI showed resorption of the lesion, which narrowed in size. Conclusion: The imaging findings of diquat poisoning encephalopathy are characteristic and the location of the lesion is characteristic, and CT and MRI have a certain diagnostic value in diquat poisoning encephalopathy, which is important for clinical treatment.

The Role of Whole Body DWI in the Evaluation of Bone Disease in Multiple Myeloma / 中国实验血液学杂志

OBJECTIVE@#To explore the characteristics of ADC value changes in DWI of newly diagnosed symptomatic MM patients and its correlation with R-ISS stage.@*METHODS@#The data of 148 newly diagnosed symptomatic MM patients treated by whole-body DWI scan at The First Affiliated Hospital of Soochow University from June 2016 to June 2019 were selected and retrospectively analyzed and 30 cases of age-matched healthy people were selected as controls. The differences of ADC values between the patients in normal control group, DWI- group and DWI+ group were compared, and the relationship between ADC values and R-ISS stage in MM patients was compared.@*RESULTS@#The plasma cell percentage of the patients in DWI+ group was higher than those in DWI- group. ADC values of vertebra, sternum, rib, pectoral girdle, pelvic girdle of the patients in DWI+ group were significantly higher than those in DWI- group and normal control group. The ADC values of each part of the patients in DWI- group were higher than those in normal control group. ADC values of sternum, rib and pectoral girdle in the patients at R-ISS stage III were higher than those at R-ISS stage I and II, while, there was no statistical difference between R-ISS stage I and II groups. And there was no significant difference in ADC values of other bone parts such as vertebra and pelvic girdle in patients at R-ISS stage Ⅰ-Ⅲ.@*CONCLUSION@#DWI+ in MM patients is related to higher tumor invasion. The ADC values of the DWI+ group are higher than those of the DWI- group; the bone ADC values of the DWI- patients are still higher than the normal ones. And there is a certain relationship between ADC value and R-ISS stage.

Application of Diffusion Weighted Imaging in Pathological Grading/Typing and Clinical Staging of 95 Cases of Cervical Adenocarcinoma / 中国医学科学院学报

Objective To investigate the correlations of diffusion weighted imaging (DWI) with pathological grading,typing and clinical staging of cervical adenocarcinoma. Methods The data of 95 patients with cervical adenocarcinoma from May 2011 to February 2018 in Cancer Hospital Chinese Academy of Medical Sciences were collected for retrospective analysis.Before treatment,conventional MRI and DWI (b=0,800 s/mm2) were performed,and the apparent diffusion coefficient (ADC) value of cervical adenocarcinoma was measured.The ADC values were compared among different pathological grades,types,and clinical stages. Results The mean ADC value was (1.00±0.25)×10-3 mm2/s in the poorly differentiation group,(1.09±0.25)×10-3 mm2/s in the moderately differentiation group,and (1.22±0.20)×10-3 mm2/s in the well differentiation group,which showed significant difference between the poorly and well differentiation groups (P=0.002).The mean ADC values were (1.04±0.24) ×10-3 mm2/s and (1.21±0.26)×10-3 mm2/s in the endocervical adenocarcinoma (usual type) group and mucinous carcinoma group,respectively,which showed significant difference (P=0.005). Conclusions The worse differentiation of cervical adenocarcinoma corresponded to the lower ADC value.The ADC value of mucinous carcinoma was higher than that of endocervical adenocarcinoma (usual type).

Evaluation of non-contrast magnetic resonance imaging as an imaging surveillance tool for hepatocellular carcinoma in at-risk patients

INTRODUCTION@#This study aimed to evaluate the potential of non-contrast-enhanced magnetic resonance (MR) imaging as an imaging surveillance tool for detection of hepatocellular carcinoma (HCC) in at-risk patients and to compare the performance of non-contrast MR imaging with ultrasonography (US) as a screening modality for the same.@*METHODS@#In this retrospective study, patients diagnosed with HCC between 1 January 2010 and 31 December 2015 were selected from our institution's cancer registry. Patients who underwent MR imaging and had US performed within three months of the MR imaging were included. For each MR imaging, two non-contrast MR imaging sequences - T2-weighted fat-saturated (T2-W FS) sequence and diffusion-weighted imaging (DWI) - were reviewed for the presence of suspicious lesions. A non-contrast MR image was considered positive if the lesion was seen on both sequences. The performance of non-contrast MR imaging was compared to that of hepatobiliary US for the detection of HCC.@*RESULTS@#A total of 73 patients with 108 HCCs were evaluated. Sensitivity of non-contrast MR imaging for the detection of HCC using T2-W FS and DWI was 93.2%, which was significantly higher than that of US, which was 79.5% (p = 0.02). In a subgroup of 55 patients with imaging features of liver cirrhosis, the sensitivity of non-contrast MR imaging was 90.9%, which was also significantly higher than that of US, which was 74.5% (p = 0.02).@*CONCLUSION@#Our pilot study showed that non-contrast MR imaging, using a combination of T2-W FS and DWI, is a potential alternative to US as a screening tool for surveillance of patients at risk for HCC.

Application of non-contrasted computed tomography and diffusion-weighted imaging protocols for endovascular treatment selection in patients with late-presenting or wake-up strokes / Aplicação de tomografia computadorizada sem contraste e protocolos de imagem ponderada em difusão para seleção de tratamento endovascular em pacientes com acidente vascular cerebral em fase tardia ou ao despertar

ABSTRACT Background: Among patients with acute ischemic stroke with a mismatch between deficit severity and infarct volume, thrombectomy performed within a 6-24 hours time window has efficacy and safety similar to treatment within 6 hours. However, whether magnetic resonance imaging with T2 diffusion-weighted imaging (DWI) is feasible remains to be validated. Objective: To investigate prognosis among stroke patients receiving endovascular treatment (EVT) within 6 hours and 6-24 hours using non-contrasted computed tomography (NCCT) and DWI. Methods: Overall, 209 anterior-circulation ischemic stroke patients with large-vessel occlusion who underwent EVT were divided into ≤ 6 hours and 6-24 hours groups. Patients presenting symptoms within 6 hours were treated if their NIHSS score was ≥ 7 and ASPECTS score was ≥ 5, whereas those with wake-up stroke (WUS) or presenting symptoms 6-24 hours after last seen well (WUS/late-presenting stroke, LPS) were managed if their NIHSS score was ≥ 7 and ASPECTS score was ≥ 5. Results: The percentages of patients undergoing intracranial stenting and intracranial ballooning without stenting significantly differed between two groups (p < 0.001). Grades 0, 1, 2a and 2b recanalization rates did not differ between the 6 hours and 6-24 hours groups (all p > 0.05). Grade 3 recanalization rate in the 6 hours group was significantly lower than in the 6-24 hours group (p = 0.043). The 3-month Rankin Scale score did not significantly differ between the two groups (p = 0.629). Conclusions: EVT is a safe and effective treatment for patients with WUS and LPS selected through NCCT and DWI-based simple imaging.

RESUMO Antecedentes: Entre pacientes com acidente vascular cerebral isquêmico (AVCI) agudo com divergência entre gravidade do déficit e volume do infarto, a trombectomia em 6 a 24 horas tem eficácia e segurança semelhantes ao tratamento em até 6 horas. Entretanto, a viabilidade da imagem ponderada em T2 com difusão (DWI) da ressonância magnética necessita validação. Objetivo: Investigar o prognóstico de pacientes com AVCI que recebem tratamento endovascular (EVT) em até 6 horas e de 6-24 horas usando tomografia computadorizada sem contraste (NCCT) e DWI. Métodos: Duzentos e nove pacientes com AVCI de circulação anterior submetidos a EVT foram divididos em ≤ 6 horas e 6-24 horas. Pacientes com sintomas até 6 horas foram tratados se NIHSS ≥ 7 e ASPECTS ≥ 5; aqueles com AVCI ao despertar (WUS) ou com sintomas entre 6-24 horas da última vez em que foram vistos bem (WUS/AVC de fase tardia, LPS) foram tratados se NIHSS ≥ 7 e ASPECTS ≥ 5. Resultados: As porcentagens de pacientes submetidos a implante de stent intracraniano e angioplastia intracraniana sem stent diferiram entre os dois grupos (p <0,001). As taxas de recanalização 0, 1, 2a e 2b não diferiram entre 6 horas e 6-24 horas (p> 0,05). A taxa de recanalização de grau 3 no grupo 6 horas foi menor do que 6-24 horas (p = 0,043). Pontuação na Escala Rankin (3 meses) não foi diferente (p = 0,629). Conclusões: EVT é um tratamento seguro e eficaz para pacientes com WUS e LPS selecionados por meio de imagens baseadas em NCCT e DWI.

Predictive value of magnetic resonance imaging characteristics before and after radiotherapy for the occurrence of severe radiation-induced late rectal injury in patients with rectal cancer / 中华胃肠外科杂志

Objective: Severe radiation-induced late rectal injury (sRLRI) directly affects the quality of life of patients with rectal cancer. Effective prediction of sRLRI before surgery may provide important information for the selection of surgical strategies and perioperative managements. The purpose of this study is to evaluate the feasibility of predicting sRLRI based on magnetic resonance imaging (MRI) features before and after radiotherapy for rectal cancer. Methods: This was a diagnostic study. Clinical and imaging data of 90 patients with rectal cancer receiving long-term radiotherapy from June 2013 to July 2018 in the Sixth Affiliated Hospital of Sun Yat-sen University were collected retrospectively. Case inclusion criteria: (1) rectal cancer was diagnosed by pathology and age of ≥ 18 years old; (2) patients received neoadjuvant chemoradiotherapy and anterior rectal resection; (3) follow up time ≥ 3 years; (4) patients had no history of other neoplasm. Exclusion criteria: (1) patients did not receive MRI examination in our hospital within 2 weeks before and/or 8 weeks after radiotherapy; (2) images were not good enough for evaluation; (3) medical records were incomplete; (4) patients had severe gastrointestinal diseases. According to the RTOG/EORTC classification criteria for radiation reactions, severe complications of grade 3-4 requiring surgical management were defined as sRLRI. T2WI and DWI images before and after radiotherapy were evaluated. The rectal wall thickness, bladder wall thickness, rectal sacral spacing and apparent diffusion coefficient (ADC) were measured. The receiver operating characteristic (ROC) curve was used to evaluate the predictive value of the above indicators for sRLRI. Results: Among the 90 patients with rectal cancer, 34 (37.8%) developed sRLRI. Before radiotherapy, the median rectal wall thickness of sRLRI and non-sRLRI patients was 4.530 mm and 4.355 mm, respectively; the median bladder wall thickness was 3.962 mm and 3.868 mm, respectively; the median rectal sacral spacing was 15.557 mm and 12.433 mm, respectively; the median ADC value of rectal wall was 1.620 ×10(-3) mm(2)/s and 1.653 ×10(-3) mm(2)/s, respectively. There were no significant differences in above indicators between sRLRI and non-sRLRI patients (all P>0.05). After radiotherapy, compared with non-sRLRI patients, sRLRI patients had increased rectal wall thickness (median: 8.239 mm vs. 6.223 mm, Z=-3.512, P=0.001), rectal sacral spacing (median: 17.728 mm vs. 13.885 mm, Z=-2.247, P=0.025), and change of rectal wall thickness after radiotherapy (median: 98.106% vs. 49.584%, Z=-4.169, P<0.001). After radiotherapy, there were no significant differences in the bladder wall thickness and its change value, the ADC value of rectal wall and its change rate before and after radiotherapy between the two groups (all P>0.05). The area under the curve (AUC) of the change rates of rectal wall thickness after radiotherapy, rectal wall thickness and rectal sacral spacing after radiotherapy for predicting sRLRI was 0.763, 0.722 and 0.642, respectively, while the sensitivity was 85.3%, 70.6% and 76.5%, respectively, and the specificity was 64.3%, 71.4% and 57.1%, respectively. Conclusion: Based on MRI examinations, assessments of rectal wall thickness after radiotherapy, the change rate of rectal wall thickness after radiotherapy, and rectal sacral spacing after radiotherapy are helpful for evaluating the risk of sRLRI after radiotherapy for patients with rectal cancer.

Predictive value of combination of MRI tumor regression grade and apparent diffusion coefficient for pathological complete remission after neoadjuvant treatment of locally advanced rectal cancer / 中华胃肠外科杂志

Objective: Pelvic high-resolution magnetic resonance imaging (MRI) has now become a standard method for evaluating the efficacy of neoadjuvant treatment for locally advanced rectal cancer (LARC). However, this traditional morphological qualitative assessment method based on T2-weighted imaging (T2WI) is not effective in predicting pathological complete remission (pCR). The purpose of this study is to investigate whether combining the magnetic resonance tumor regression grade (mrTRG) with apparent diffusion coefficient (ADC) can improve diagnostic value for pCR after preoperative neoadjuvant chemoradiotherapy (nCRT) of LARC. Methods: This was a diagnostic study. Clinicopathological data of 134 LARC patients who received nCRT and radical surgery in the First Affiliated Hospital of Kunming Medical University from January 2017 to December 2019 were retrospectively analyzed. All the patients underwent MRI which included T2WI and DWI sequences before and 8 weeks after nCRT. Two radiologists independently drew ROIs on T2WI and DWI to estimate mrTRG stage and calculate the mean ADC value. Receiver operating characteristics (ROC) method was applied to evaluate the predict value of mrTRG combined with mean ADC value for pCR. Results: Of 134 LARC patients, 85 were male and 49 were female with median age of 58 (28-82) years. After nCRT, MRI suggested 21 patients (15.7%) had clinical complete remission (cCR), e.g. mrTRG stage 1-2. Postoperative pathology revealed 31 (23.1%) patients had pCR. The evaluations of mrTRG and ADC value by the two readers were highly consistent, and the intra-group correlation coefficients were 0.83 (95% CI: 0.703-0.881) and 0.96 (95% CI: 0.989-0.996), respectively. There was a negative correlation between mrTRG and pCR (r(s)=-0.505, P<0.01), and a positive correlation between mean ADC value and pCR (r(s)=0.693, P<0.01). The ROC curve showed that mrTRG alone had a medium predictive value for pCR, with an area under the curve (AUC) of 0.832 (95% CI: 0.743-0.921); the mean ADC value had a higher predictive value for pCR, with AUC of 0.906 (95% CI: 0.869-0.962). The predictive value of the combined model of mrTRG and ADC value for pCR was significantly better than that of mrTRG alone (P=0.015), and the AUC was 0.908 (95% CI: 0.849-0.968). Conclusion: Both mrTRG and mean ADC value can be non-invasive methods to predict the efficacy of nCRT for LARC. Combining the mean ADC value with mrTRG can result in better pCR prediction.