Magnetic resonance imaging(MRI) can obtain multi-modal images with different contrast, which provides rich information for clinical diagnosis. However, some contrast images are not scanned or the quality of the acquired images cannot meet the diagnostic requirements due to the difficulty of patient's cooperation or the limitation of scanning conditions. Image synthesis techniques have become a method to compensate for such image deficiencies. In recent years, deep learning has been widely used in the field of MRI synthesis. In this paper, a synthesis network based on multi-modal fusion is proposed, which firstly uses a feature encoder to encode the features of multiple unimodal images separately, and then fuses the features of different modal images through a feature fusion module, and finally generates the target modal image. The similarity measure between the target image and the predicted image in the network is improved by introducing a dynamic weighted combined loss function based on the spatial domain and K-space domain. After experimental validation and quantitative comparison, the multi-modal fusion deep learning network proposed in this paper can effectively synthesize high-quality MRI fluid-attenuated inversion recovery (FLAIR) images. In summary, the method proposed in this paper can reduce MRI scanning time of the patient, as well as solve the clinical problem of missing FLAIR images or image quality that is difficult to meet diagnostic requirements.
Objective To investigate the situation and prospect of local recurrence of rectal cancer by using CT and MRI. Method Relevant references about the imaging diagnosis of local recurrence of rectal cancer， which were published domestic and abroad in recent years， were collected and reviewed. Results In the diagnosis of local recurrence of rectal cancer， the sensitivity of CT was higher than that of MRI， while the specificity and accuracy were not. Perfusion CT， dynamic contrast-enhanced MRI， and diffusion weighted imaging were valuable in diagnosing local recurrence of rectal cancer， as new diagnostic techniques. Conclusion Both CT and MRI are important and valuable methods in diagnosing for local recurrence of rectal cancer.
ObjectiveTo analyze the causes of unrelieved epilepsy thoroughly in children with isolated focal cortical dysplasia (FCD) based on MRI.MethodsRetrospective analysis of MRI and clinical data of 21 children with isolated FCD during July 2014 to January 2018, which confirmed by pathology and unrelieved thoroughly after operation performed, the pathological types and MRI signs were analyzed, as well as the frequency of different MRI signs in FCD of each pathological type. Analyzed the possible factors of surgical failure.ResultsAmong the 21 cases, there were 15 males and 6 females, with an average age of (5.7±0.3) years and an average course of disease of (3.4±0.5) years.MRI signs of this part of the children were mainly manifested by blurred focal gray matter boundaries, abnormal cortical structure changes (thickening and/or thinning), transmantle signs (abnormal cone signals extending from subcortical white matter to the ventricle) and abnormal gray matter signals, which were similar to MRI signs of FCD with satisfactory postoperative epilepsy control. 17 cases (80.9%) appeared epileptic discharge after operation in the EEG monitoring area 2 weeks to 6 months, FCD type I and type Ⅱ accounted for 35.3%, 64.7% respectively. During intraoperative EEG monitoring, no epileptiform discharge was observed in the transmantle sign region in 6 cases, and the region was retained, and only the surrounding abnormal discharge cortex was removed, complete removal of the tansmantle sign and surrounding abnormal discharge area was performed in 2 cases, and different degrees of epileptic epilepsy were observed in both methods.ConclusionMRI signs of isolated FCD with unrelieved epilepsy after operation were nonspecific, there were still epilepsy of varying degrees after all epileptogenic lesions have been removed, the cause may be related to potential epileptic factors.
ObjectiveTo investigate the value and feasibility of low-field MR in the diagnosis of excessive lateral pressure syndrome (ELPS) of the patellofemoral joint. MethodsThirty-seven patients confirmed to have ELPS by surgery or clinical examination between March 2010 and March 2013 were involved in this retrospective study. The injured knees of all patients were examined by SE sequence and Fat sequence, using Siemens 0.35 T MR scanner. The patella was assessed. Infrapatellar fat pad, patella tilt angle and patellofemoral joint space were measured. ResultsThere were 15 cases of type Ⅱ, 21 of type Ⅲ, and 1 of type Ⅳ knees. Three cases of bipartite were detected. Patella tilt angle: type Ⅳ > type Ⅲ > type Ⅱ. Infrapatellar fat pad had edema in 37 cases. And there were 29 cases of varying degrees of lateral patellar cartilage softening. ConclusionLow-field MRI is an effective diagnostic method of excessive lateral pressure syndrome for patellofemoral joint. STIR sequence is the best sequence for diagnosing patellofemoral excessive lateral pressure syndrome.
ObjectiveTo investigate the efficacy of vagus nerve stimulation (VNS) in patients with refractory magnetic resonance imaging (MRI)-negative epilepsy and to evaluate potential clinical predictors. MethodsA retrospective collection of efficacy data was conducted on 24 patients with intractable MRI-negative epilepsy treated with VNS, who were followed up for more than six months, at Beijing Tiantan Hospital and Beijing Fengtai Hospital from January 2016 to September 2023. Patients were divided into two subgroups based on their response to VNS: responders (≥50% reduction in seizure frequency) and non-responders (<50% reduction in seizure frequency). The relationship between preoperative clinical data and VNS efficacy was further analyzed to identify potential predictors of VNS efficacy. ResultsA total of 24 patients were included, with an average age of (14.26±8.39) years old. Seizure frequency was reduced by more than 50% in 37.5% of patients, and 8.3% of patients achieved seizure-free after VNS treatment. Preoperative seizure frequency and interictal epileptiform discharge type were significantly associated with VNS efficacy (P<0.05). Multivariate regression analysis showed that a monthly seizure frequency of less than 100 and focal interictal epileptiform discharges were independent predictors of VNS efficacy (P<0.05). ConclusionVNS is an effective treatment for patients with refractory MRI-negative epilepsy. Lower monthly seizure frequency and focal interictal epileptiform discharges are potential predictors of VNS efficacy. These findings provide important references for clinicians in selecting and evaluating patients for VNS treatment.
The registration of preoperative magnetic resonance (MR) images and intraoperative ultrasound (US) images is very important in the planning of brain tumor surgery and during surgery. Considering that the two-modality images have different intensity range and resolution, and the US images are degraded by lots of speckle noises, a self-similarity context (SSC) descriptor based on local neighborhood information was adopted to define the similarity measure. The ultrasound images were considered as the reference, the corners were extracted as the key points using three-dimensional differential operators, and the dense displacement sampling discrete optimization algorithm was adopted for registration. The whole registration process was divided into two stages including the affine registration and the elastic registration. In the affine registration stage, the image was decomposed using multi-resolution scheme, and in the elastic registration stage, the displacement vectors of key points were regularized using the minimum convolution and mean field reasoning strategies. The registration experiment was performed on the preoperative MR images and intraoperative US images of 22 patients. The overall error after affine registration was (1.57 ± 0.30) mm, and the average computation time of each pair of images was only 1.36 s; while the overall error after elastic registration was further reduced to (1.40 ± 0.28) mm, and the average registration time was 1.53 s. The experimental results show that the proposed method has prominent registration accuracy and high computational efficiency.
ObjectiveTo discuss the value of diffusion weighted imaging (DWI) in the diagnosis of placenta increta. MethodsThe clinical data of 42 patients with placenta increta admitted to Sichuan Provincial Hospital for Women and Children between May 2012 and January 2014 were retrospectively analyzed. All the patients were examined by prenatal magnetic resonance scans and DWI scans for subsequent comparison between ADC of the local convex placental region and ADC of the normal placental region and between the results of the two imaging methods. ResultsADC of the implantation area was significantly different from that of the normal placenta, so it could be used as a quantitative index. DWI had a higher sensitivity of diagnosis than conventional MRI. ConclusionCompared with conventional magnetic resonance imaging, DWI is more valuable in the clinical diagnosis of placenta increta, which provides a reliable basis for clinical treatment.
【Abstract】Objective To investigate the MR imaging （MRI） appearances of postoperative residual liver after hepatic resection for hepatocellular carcinoma (HCC) and the MRI features of tumor recurrences.Methods Twenty patients with previous surgical resection of HCC underwent MR examination of upper abdomen for routine follow-up study or due to clinical suspicion of tumor recurrence. MRI protocol included T1W axial unenhanced images and Gadoliniumenhanced sequences, Gadolinium-enhanced VIBE sequence, unenhanced T2W axial images and coronal TrueFisp sequence.Results Thirteen patients showed normal edge of surgical resection, while 6 patients demonstrated MR signs of incision edge recurrence of HCC and 1 patient was suspicious of tumor recurrence at the incision edge. Among the 20 patients, 12 had MRI features of tumor recurrence of the residual liver, including invasion of left, right and common hepatic ducts 3 cases. Three patients had metastatic lymphadenopathy in portal hepatis, portacaval space and retroperitoneal space. Two patients showed extensive tumor implantation of peritoneum and mesentery. Conclusion MRI is effective in differentiating normal surgical incision edge of residual liver from tumor recurrence. It is also very useful for the early detection of intrahepatic and extrahepatic tumor lesions.
Objective To investigate the feasibility of imaging of bone marrow mesenchymal stem cells (BMMSCs) labeled with superparamagnetic iron oxide(SPIO) transplanted into coronary artery in vivo using magnetic resonance imaging (MRI), and the redistribution of the cells into other organs. Methods BMMSCs were isolated, cultured from bone marrow of Chinese mini swine, and double labeled with SPIO and CMDiI(Cell TrackerTM C-7001). The labeled cells were injected into left anterior descending coronary artery through a catheter. The injected cells were detected by using MRI at 1 week,3weeks after transplantation. And different organs were harvested and evaluated the redistribution of transplanted cells through pathology. Results The SPIO labeled BMMSCs injected into coronary artery could be detected through MRI and confirmed by pathology and maintained more than 3 weeks. The SPIO labeled cells could be clearly imaged as signal void lesions in the related artery. The pathology showed that the injected cells could be distributed into the area of related artery, and the cells injected into coronary artery could be found in the lung, spleen, kidney, but scarcely in the liver, the structures of these organs remained normal. Conclusion The SPIO labeled BMMSCs injected into coronary artery can be detected by using MRI, the transplanted cells can be redistributed into the non-targeted organs.
Objective To evaluate the diagnostic value of magnetic resonance cholangiopancreatography (MRCP) in obstructive jaundice. Methods Forty eight consecutive patients with obstructive jaundice were examined by MRCP, all results were testified during and /or after operation. Results Different causes of obstruction had their own characteristic manifestations. Level of obstruction was accurate in 100%, the accuracy in distinguishing obstructive causes was 93.8%. Conclusion MRCP is quite effective, safe and reliable in diagnosis of obstructive jaundice.