摘要:目的: 探討臂叢神經磁共振成像的技術方法及其可行性。 方法 :對15例正常志愿者行雙側臂叢神經成像:包括常規快速自旋回波序列T1加權(T1W/TSE)、快速自旋回波序列T2加權(T2W/TSE)、快速自旋回波序列T2加權加SPIR脂肪抑制(T2W/SPIR)冠狀位掃描以及彌散加權背景抑制成像序列(DWIBS)軸位掃描。 結果 :T1W/TSE、T2W/TSE、及T2W/SPIR對臂叢節后神經同層顯示率分別為533%、567%和833%;DWIBS MIP重建圖像對臂叢神經的全貌顯示較為完整、清晰、直觀;T1W/TSE、T2W/TSE、T2W/SPIR及DWIBS MIP重建圖像的對比噪聲比分別為109±09、107±13、185±68和299±133,T2W/SPIR序列和DWIBS MIP重建圖像的對比噪聲比明顯高于T1W/TSE和T2W/TSE序列。 結論 :T2W/SPIR序列對臂叢神經的同層顯示率及圖像的對比噪聲比明顯高于常規T1W/TSE、T2W/TSE序列, DWIBS MIP重建圖像能夠顯示臂叢神經的全貌,兩者為臂叢神經成像較為有效的技術方法,對于臂叢神經病變的診斷即具有十分重要的意義。Abstract: Objective: To determine the optimal sequences of brachial plexus with MRI. Methods : Fifteen volunteers were underwent MRI on 15T scanner, the Sequences of T1W/TSE/COR, T2W/TSE/COR, T2W/SPIR/COR and Diffusionweighted imaging with background body signal suppression were performed. Results : The display rates of brachial plexus postganglionic segment nerve showing at the same slice were 533%, 567% and 833% on T1W/TSE/COR, T2W/TSE/COR, T2W/SPIR/COR. Brachial plexus on DWIBS MIP were clear and complete. Contrastnoise ratio of four sequences was 109±09, 107±13, 185±68 and 299±133,respectively. Contrastnoise ratio of T2W/SPIR/COR and DWIBS MIP was significantly higher than that of the other two sequences. Conclusion : Display rate of brachial plexus and contrastnoise ratio of images on T2W/SPIR/COR were higher than those of routine sequences. Image of DWIBS MIP can show the outline of brachial plexus clearly. The two sequences were reliable and effetive techoniquic in diagnosis of brachial plexus lesion.
Because of the long acquisition time and spin-echo planar imaging sequence, diffusion weight magnetic resonance image (DWI) should be denoised effectively to ensure the follow-up applications. The commonly used denoising methods which induced from gray level image lack the use of the specific information from multiple magnitude directions. This paper, therefore, proposes a modified linear minimum mean square error (LMMSE) denosing method used for DWI. The proposed method uses the local information to estimate the parameter of the Rician noise and modifies the LMMSE using the information of multiple magnitude directions synthetically. The simulation and experiment of the synthetic DWI and real human brain DWI dataset demonstrate that the proposed method can more effectively remove the Rician noise compared to the commonly used denoising method and improve the robustness and validity of the diffusion tensor magnetic resonance image (DTI).
Objective To explore the accuracy of contrast-enhanced magnetic resonance imaging (MRI) in predicting pathological complete remission (pCR) in breast cancer patients after neoadjuvant therapy (NAC). Methods The clinicopathological data of 245 patients with invasive breast cancer who had completed the surgical resection after NAC in the Affiliated Hospital of Southwest Medical University from March 2020 to April 2022 were collected retrospectively. According to the results of hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) detected by immunohistochemistry, all patients were divided into four subgroups: HR+/HER2–, HR+/HER2+, HR–/HER2+ and HR–/HER2–. The value of MRI in evaluating the efficacy of NAC was analyzed by comparing the postoperative pathological results as the gold standard with the residual tumor size assessed by preoperative MRI. Meanwhile, the sensitivity, specificity and positive predictive value (PPV) of pCR predicted by the evaluation results of enhanced MRI were analyzed, and further analyzed its predictive value for pCR of different subtypes of breast cancer. Results There were 88 cases (35.9%) achieved radiological complete response (rCR) and 106 cases (43.3%) achieved pCR in 245 patients. Enhanced MRI in assessing the size of residual tumors overestimated and underestimated 12.7% (31/245) and 9.8% (24/245) of patients, respectively. When setting rCR as the MRI assessment index the specificity, sensitivity and PPV were 84.2% (117/139), 62.3% (66/106) and 75.0% (66/88), respectively. When setting near-rCR as the MRI assessment index the specificity, sensitivity and PPV were 70.5% (98/139), 81.1% (86/106), and 67.7% (86/127), respectively. The positive predictive value of both MRI-rCR and MRI-near-rCR in evaluating pCR of each subtype subgroup of breast cancer was the highest in the HR–/HER2+ subgroup (91.7% and 83.3%, respectively). In each subgroup, compared with rCR, the specificity of near-rCR to predict pCR decreased to different degrees, while the sensitivity increased to different degrees. Conclusions Breast contrast-enhanced MRI can more accurately evaluate the efficacy of localized breast lesions after NAC, and can also more accurately predict the breast pCR after NAC. The HR–/HER2+ subgroup may be a potentially predictable population with pCR exemption from breast surgery. However, the accuracy of the evaluation of pCR by breast enhancement MRI in HR+/HER2– subgroup is low.
One of the main technical challenges when integrating magnetic resonance imaging (MRI) systems with medical linear accelerator is the strong interference of fringe magnetic fields from the MRI system with the electron beams of linear accelerator, making the linear accelerator not to work properly. In order to minimize the interference of magnetic fields, a magnetic shielding cylinder with an open structure made of high permeability materials is designed. ANSYS Maxwell was used to simulate Helmholtz coil which generate uniform magnetic field instead of the fringe magnetic fields which affect accelerator gun. The parameters of shielding tube, such as permeability, radius, length, side thickness, bottom thickness and fringe magnetic fields strength are simulated, and the data is processed by MATLAB to compare the shielding performance. This article gives out a list of magnetic shielding effectiveness with different side thickness and bottom thickness under the optimal radius and length, which showes that this design can meet the shielding requirement for the MRI-linear accelerator system.
ObjectiveTo investigate the value of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI) in gross morphological classification of hepatocellular carcinoma (HCC). MethodsThe clinicopathologic data of patients with HCC who received surgical treatment in the Affiliated Huai’an Hospital of Xuzhou Medical University from January 2017 to December 2022 were retrospectively gathered. The Gd-EOB-DTPA-MRI was performed before operation. Two radiologists independently assessed the gross morphological classification of HCC according to the imaging performance. The tumors were cut into sections in a coronal plane and were taken pictures for recording pathological features after operation. The tumors were assigned into 4 types according to the references and clinical experiences: single nodular type (SN), single nodular with extranodular growth type (SN-EG), confluent multi-nodular type (CMN), and infiltration type (IF). Matching degree of morphological classification was analyzed between by the Gd-EOB-DTPA-MRI and resected specimen. The pathological features of 4 types of HCC were also analyzed. ResultsA total of 87 patients with HCC were included. The gross morphological classification by the Gd-EOB-DTPA-MRI was 28 (32.2%) patients with SN, 28 (32.2%) patients with SN-EG, 21 (24.1%) patients with CMN, 10 (11.5%) patients with IF, which by the resected specimen was 33 (37.9%) patients with SN, 24 (27.6%) patients with SN-EG, 21 (24.1%) patients with CMN, and 9 (10.4%) patients with IF in the 87 patients with HCC. The Kappa’s coefficient of agreement between the results of Gd-EOB-DTPA-MRI and postoperative resection specimens was 0.776 (P=0.199). There were statistical differences in the tumor diameter and microvascular invasion (MVI) among the 4 types of gross morphology classification (F=2.937, P=0.038; χ2=16.852, P=0.001), the MVI rate was highest and tumor diameter was biggest in the patients with IF among the 4 types of gross morphology classification (P<0.05). ConclusionsFrom the results of this study, the gross morphological classification of HCC is closely related to the tumor diameter and MVI. Results of Gd-EOB-DTPA-MRI and postoperative resection specimens in assessing the gross morphological classification are good agreement. Therefore, an accurate preoperative planning and better therapy strategy for the patients with HCC can be provided according to gross morphological classification by preoperative Gd-EOB-DTPA-MRI.
Objective To summarize the CT, MRI, and positron emission computed tomography (PET) imaging findings of hematologic malignancies of the pancreas, so as to improve the capacity of its diagnosis. Methods After searching articles concerning radiological research about hematologic malignancies of the pancreas, summarizing its imaging characteristics. Results Hematologic malignancies of the pancreas include pancreatic lymphoma, pancreatic multiple myeloma, myeloid sarcoma, posttransplantation lymphoproliferative disorder, and giant lymph node hyperplasia. ① Pancreatic lymphoma: imaging features of pancreatic lymphoma are segmental or diffuse homogeneous enlargement of the pancreas, diameter of mass >5 cm, adenopathy below the level of renal veins, and lack of pancreatic duct dilation. Blurred margins of pancreas by lymphadenopathy is highly suggestive of lymphoma. ② Pancreatic multiple myeloma: pancreatic multiple myeloma are hyperintense on both T1- and T2-weighted images. ③ Pancreatic granulocytic sarcoma: pancreatic granulocytic sarcoma present as homogeneous hypoenhancing mass on CT, usually without pancreatic duct dilation. On MRI, the lesions are isointense and mildly hyperintense on T1- and T2-weighted images respectively. ④ Posttransplantation lymphoproliferative disorder: diameter of leison of posttransplantation lymphoproliferative disorder usually is >5 cm with poor enhancement. Lesions are mildly hyperintense on T2-weighted images and extremely hypermetabolic on PET images. ⑤ Giant lymph node hyperplasia: it mainly appear as solitary noninvasive masses. Punctate calcification and surrounding supply vessels are observed in hyaline vascular type. Plasma cell type demonstrate unapparent enhancement and less calcification. Conclusions Hematologic malignancies of the pancreas manifest different imaging features on CT, MRI, and PET. Familiarity with such characteristics helps to early recognize diseases and determine next-step measures.
Through magnetic resonance electrical properties tomography (MR-EPT), electrical conductivity and permittivity of biological tissues could be reconstructed based on radio frequency field of magnetic resonance imaging (MRI) system. High precision and high resolution image could be obtained without current injection. In this study, XFDTD software was used to establish a finite element model of the human breast. Simulation was delivered at the Larmor frequency of 128 MHz by a 16-channel radio frequency coil. Conductivity and permittivity of the mammary tissue was reconstructed according to the B1+ field's amplitude and phase of forward problem. Anti-noise performance of the algorithm was studied by adding noise to B1+ field. The conductivity and permittivity's average relative error between simulation results and dielectric constant was 4.71% and 11.32%, respectively. With a signal-to-noise ratio of >30 dB, the noise added would not affect imaging results. This study demonstrated that high precision and high resolution image could be obtained by MR-EPT without excitation. MR-EPT had excellent feasibility and developing potential in early detection of diseases.
Objective To explore the differential diagnosis significance of 3.0T MRI united-sequences examination in the diagnosis of benign and malignant breast lesions. Methods A total of 67 breast lesions of 59 patients were collected prospectively, which be treated at the Sichuan Provincial People’s Hospital during July 2015 to January 2017. All patients were underwent bilateral breast 3.0T magnetic resonance plain scan, diffusion weighted imaging, and dynamic enhanced scan successively before surgical operation. Analysis of morphological features of the benign and malignant breast lesions, the time-signal intensity curve (TIC), the apparent diffusion coefficient (ADC), and the combination diagnosis of them were performed. Results Of all 59 patients, 67 lesions were confirmed by histopathology, including 18 benign lesions and 49 malignant lesions. The morphological features (including margin, shape, border, and evenness), the types of TIC of dynamic enhancement, and ADC value between the benign lesions and malignant lesions were statistically significant (P<0.05). The sensitivity and specificity of Fischer scoring system was 89.8% (44/49) and 61.1% (11/18) respectively. The sensitivity and specificity of TIC types was 83.7% (41/49) and 77.8% (14/18) respectively. The diagnostic threshold of ADC value was 1.012×10–3 mm2/s, with the sensitivity and specificity for the diagnosis was 91.8% (45/49) and 83.3% (15/18) respectively. The sensitivity and specificity of the combination of Fischer scoring system and TIC type for diagnosis between benign and malignant breast lesions was 95.9% (47/49) and 72.2% (13/18) respectively. The sensitivity and specificity of the combination of Fischer scoring system, TIC type, and ADC value for benign and malignant breast lesions was 98.0% (48/49) and 83.3% (15/18) respectively. Conclusion The combination of Fischer scoring system, TIC type, and diffusion-weighted imaging for the differential diagnosis between benign lesions and malignant lesions was more effective than single imaging method.
ObjectiveTo summarize the application of magnetic resonance imaging (MRI) in the evaluation of pancreatic exocrine function.MethodIn this paper, we reviewed and summarized the related literatures about the application of MRI in the field of pancreatic exocrine function evaluation in recent years.ResultsA variety of MRI techniques could be used to detect the pancreatic exocrine function. In addition to conventional MRI techniques, there were also MRI stimulated by pancreatic secretions, cine (dynamic) cholangiopancreatography based on space selective reverse recovery pulse, and so on.ConclusionThe new MRI techniques have potential for semi-quantitative and quantitative evaluation of pancreatic exocrine function.
摘要:目的:探討平山病的MRI影像特點及其臨床應用價值。方法:5例臨床確診平山病病例組和10例正常對照組進行頸椎自然位及屈頸位MRI檢查,矢狀位T1WI、T2WI及軸位T2WI,觀察頸髓、蛛網膜下腔及硬膜外腔變化情況。結果:病例組的5例平山病均系16~20歲男性。自然位:5例下位頸髓均萎縮變扁,硬膜外間隙未顯示增寬。屈頸位:5例C5~7頸髓前移變扁中,將變扁頸髓又分為上中下三段,以中段最窄,上下段漸移行至正常;C5~7蛛網膜下腔亦變窄,硬脊膜伴隨前移;而C4~7硬脊膜后間隙則增寬,呈新月形影,增寬程度分為輕、中、重三度,最重者位于C6椎體平面,T2加權像及T1WI增強呈高信號,其中1例內見血管流空信號影。對照組為10例志愿者,自然位: 4例C3~7頸髓形態、大小基本一致,6例頸髓自頸3逐漸移行與胸1脊髓其大小一致;屈頸位:頸髓和蛛網膜下腔大小與自然位比較無明顯變化,硬膜后間隙自C3平面向下延至T1平面,T2WI上呈均勻線樣高信號影。結論:下位頸髓萎縮變扁,屈頸位頸髓及硬脊膜前移、硬脊膜后間隙增寬呈新月形影等,是臨床診斷平山病較特征性的MRI表現。Abstract: Objective: To evaluate clinical value and MRI features of Hirayama disease. Methods: Five cases of hirayama disease, which had been clinically confirmed using siemens sonata 1.5T MRI scan, physiological condition and flexional condition, Sagittal view T1WI, T2WI and Axial View T2WI, and GdDTPA enhanced examination, for MRI changes of spinal cord, subarachnoid cavity, duramater of spinal membrae and extra dural space, etc were studied. Results: In case group of 5 cases of hirayama disease, age was mainly in 16–20 years old, All of 5 cases were men. Which were pressed and become thinner of spinal cord, strictic changes of subarachnoid cavity, new moony shape and enlargement changes and pushed forward of extra duramater space, and higher intensity signal of GdDTPA enhancement, and vascular flow effect (one case ) in C5–C7. but also, for contrast group 10 cases of normal volunteer, physiological condition:4 cases in cervical spinal cord with shape and structure were uniformity, and duramater, subarachnoid cavity, extra duramater space etc in C3–C7 were abnormal. Six cases in cervical spinal cord with shape and structure gradully changed from C3 to T1; flexional condition: 10 cases of MRI changes of spinal cord, subarachnoid cavity were as same as it in physiological condition,all of T2 WI, higher intensity signal were homogeneous of extraduramater space in C3–T1. Conclusion: The feature findings of cervical spinal cord became thinner, and cervical cord, durameter pussed forward, new moony shape and enlargment of extradurameter space, vascular flow effusion, etc in MRI were useful value for clinical diagnosis.