Application of echo-planar imaging correction in diffusion weighted imaging and diffusion tensor imaging of cervical spinal cord / 中华放射学杂志

Objective:To explore the value of echo-planar imaging correction (EPIC) for improving image quality of diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) of cervical cord.Methods:A total of 33 subjects (20 males, 13 females) were scanned on a 3.0 T MR scanner from January to March 2022, and the sequences included T 1WI, DWI and DTI (with and without corrections). Two observers delineated the regions of interest (ROIs) on the fused images of DWI and DTI with T 1WI before and after correction, and measured the average diffusion coefficient (ADC), fractional anisotropy (FA), and offset distance of ROIs between images with and without corrections. The subjective scores of image quality were also evaluated. The ICC or Kappa was used to test the consistency of the quantitative measurement and subjective scores by the two observers. The average values by the two observers would be used for subsequent analysis. The independent pair t-test and Wilcoxon test were used for comparison of objective measurements and Mann-Whitney U test was used for subjective image assessments between images with and without corrections. Results:The measurement data and the subjective scores of the two observers were in good agreement (ICC 0.912-0.999, Kappa 0.778-0.816). The independent sample t-test showed the subjective scores were significantly different for the DWI and DTI images between before and after geometry and/or ADC corrections. The ADC values of C6, the offset distances measured by DWI before and after correction of C4, C5, and C6 and subjective scores were significantly different ( P<0.05); The FA values of C1 and C3, ADC values of C1 and C3, offset distance of C4, C5 and C6 measured by DTI before and after correction and subjective scores were statistically significant ( P<0.001). Conclusion:EPI geometry correction and ADC value correction can significantly reduce geometric distortion, increase image quality, and thus improve the diagnosis accuracy of essential diseases.

Thyroid-Associated Orbitopathy: Evaluating Microstructural Changes of Extraocular Muscles and Optic Nerves Using Readout-Segmented Echo-Planar Imaging-Based Diffusion Tensor Imaging

OBJECTIVE: We aimed to investigate the ability of readout-segmented echo-planar imaging (rs-EPI)-based diffusion tensor imaging (DTI) in assessing the microstructural change of extraocular muscles (EOMs) and optic nerves in patients with thyroid-associated orbitopathy (TAO) as well as in evaluating disease activity.MATERIALS AND METHODS: We enrolled 35 TAO patients and 22 healthy controls (HCs) who underwent pre-treatment rs-EPI-based DTI. Mean, axial, and radial diffusivity (MD, AD, and RD) and fractional anisotropy (FA) of the medial and lateral EOMs and optic nerve for each orbit were calculated and compared between TAO and HC groups and between active and inactive TAO groups. Factors such as age, sex, disease duration, mediation, and smoking history between groups were also compared. Logistic regression analysis was used to evaluate the predictive value of significant variables for disease activity.RESULTS: Disease duration was significantly shorter in active TAOs than in inactive ones (p < 0.001). TAO patients showed significantly lower FA and higher MD, AD, and RD than HCs for both medial and lateral EOMs (p < 0.001), but not the AD value of lateral EOMs (p = 0.619). Active patients had significantly higher FA, MD, and AD than inactive patients for medial EOMs (p < 0.005), whereas only FA differed significantly in the lateral EOMs (p = 0.018). The MD, AD, and RD of optic nerves were significantly lower in TAO patients than HCs (p < 0.05), except for FA (p = 0.129). Multivariate analysis showed that the MD of medial EOMs and disease duration were significant predictors for disease activity. The combination of these two parameters showed optimal diagnostic efficiency for disease activity (area under the curve, 0.855; sensitivity, 68.4%; specificity, 96.9%).CONCLUSION: rs-EPI-based DTI is promising in assessing microstructural changes of EOMs and optic nerves and can help to indicate the disease activity of TAO, especially through the MD of medial EOMs.

Analysis of Apparent Diffusion Coefficients of the Brain in Healthy Controls: A Comparison Study between Single-Shot Echo-Planar Imaging and Read-out-Segmented Echo-Planar Imaging

OBJECTIVE: To compare apparent diffusion coefficients (ADCs) of brain segments by using two diffusion-weighted imaging acquisition modes, single-shot echo-planar imaging (ss-EPI) and read-out-segmented echo-planar imaging (rs-EPI), and to assess their correlation and agreement in healthy controls. MATERIALS AND METHODS: T2-weighted (T2W) images, rs-EPI, and ss-EPI of 30 healthy subjects were acquired using a 3T magnetic resonance scanner. The T2W images were co-registered to the rs-EPI and ss-EPI, which were then segmented into the gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) to generate masking templates. ADC maps of rs-EPI and ss-EPI were also segmented into the GM, WM, and CSF by using the generated templates. ADCs of rs-EPI and ss-EPI were compared using Student's t tests and correlated using Pearson's correlation coefficients. Bland-Altman plots were used to assess the agreement between acquisitions.

Clinical value of high-resolution T2-weighted magnetic resonance imaging combined with readout-segmented echo-planar imaging in differential diagnosis of muscle and non-muscle invasive bladder cancer / 第二军医大学学报

Objective To evaluate the clinical value of high-resolution T2-weighted magnetic resonance imaging (HR-T2WI), readout-segmented echo-planar imaging (RS-EPI) and HR-T2WI plus RS-EPI in differentiating non-muscle invasive bladder cancer (NMIBC) and muscle invasive bladder cancer (MIBC). Methods A prospective study was conducted on 95 patients with bladder cancer identified by cystoscope biopsy, who underwent surgery treatment in our hospital from Jun. 2016 to Dec. 2017. All 95 patients had clear pathological staging, and received HR-T2WI and RS-EPI examination. NMIBC and MIBC were differentiated using HR-T2WI, RS-EPI and HR-T2WI plus RS-EPI, and the diagnosis results were compared with the pathological results using Kappa test. The receiver operating characteristic (ROC) curve was drawn and the area under curve (AUC) of ROC was calculated to evaluate the sensitivity, specificity, accuracy of HR-T2WI, RS-EPI and HR-T2WI plus RSEPI. DeLong test was used to compare the AUC of three methods. Results The diagnostic results of HR-T2WI, RS-EPI and HRT2WI plus RS-EPI had good agreement with the pathological results (Kappa=0.770, 0.787 and 0.936; all P<0.01). The AUC, sensitivity, specificity and accuracy of HR-T2WI, RS-EPI and HR-T2WI plus RS-EPI were 0.899, 95.5% (42/44), 82.4% (42/51) and 88.4% (84/95), 0.891, 84.1% (37/44), 94.1% (48/51) and 89.5% (85/95), and 0.966, 93.2% (41/44), 100.0% (51/51) and 96.8% (92/95), respectively. The AUC of HR-T2WI+RS-EPI was higher than that of HR-T2WI and RS-EPI (Z=-2.627 8 and -2.720 5, P=0.008 6 and 0.006 5). Conclusion HR-T2WI plus RS-EPI can be used as a preoperative non-invasive examination method to differentiate NMIBC and MIBC.

Comparison study of readout-segmented EPI and single-shot EPI in DWI of orbit in healthy adults / 中国医学影像技术

Objective To explore the feasibility of the applicatoin of readout-segmented echo-planar imaging (RS-EPI) at 3.0T MR of the orbit DWI and compared with single-shot echo-planar imaging (SS-EPI).Methods Forty-two volunteers underwent both standard SS-EPI and RS-EPI DWI of the orbit at a 3.0T MR unit.Two sets of DWI images were independently qualitatively scored in the number of distinguishable normal structures,fat suppression,ghosting artifact and overall image quality.SNR of the vitreous body,geometric distortion ratio (GDR) in both anterior-posterior (AP) and right-left (RL) direction,and ADC value of the vitreous body and pons were also quantitatively calculated and compared between two sets of DWI images.The statistical analysis was performed.Results For qualitative assessment,the RS-EPI was superior to SS-EPI on the number of distinguishable normal structures (P=0.009 0),ghosting artifact (P＜0.000 1),and overall image quality (P＜0.000 1),while no significant difference was found on fat suppression (P=0.753 9).For quantitative assessment,RS-EPI had significantly lower GDR than the SS-EPI in both AP and RL direction (P=0.001 4,0.001 7).The SNR in RS-EPI was significantly lower than that of SS-EPI (P=0.004 0).Meanwhile,there was no significant difference of ADC on vitreous body and pons between RS-EPI and SS-EPI (P=0.143 8,0.126 2).Conclusion The RS-EPI can provide better image quality than SS-EPI protocol in orbital DWI at 3.0T MR imaging.

Relation between NEW-TOAST classification and glucose level in patients with acute ischemic stroke / 中华神经科杂志

ObjectiveTo investigate the relation between each subtype of cerebral ischemic stroke classified by NEW-TOAST criteria and the levels of blood sugar. MethodsA retrospective study in 624 patients hospitalized with acute cerebral ischemic stroke. All the patients were classified using NEW-TOAST classification standard. Blood glucose in patients with different stroke subtypes was recorded, and analyzed for the incidence of abnormal glucose metabolism in each subtype. The correlation of glucose to blood sugar,blood pressure and blood fat was analyzed using odd ratio (OR) and 95％ confidence intervals (CI).Results(1) Among 624 patients, the most common stroke subtype by NEW-TOAST classificationis atherothrombosis (AT), followed by small arterial occlusion (SAO). One hundred and nineteen patients (19. 1％ ) had diabetes history; another 40 patients(7.5％ ) were newly diagnosed with diabetes in this study; and 71 patients ( 11.4％ ) were found to have glycoregulation abnormality. The incidence of abnormal glycometabolism was high in patients with AT ( 40. 4％ ) and SAO ( 39. 7％ ). ( 2 ) Association analysis between stroke subtypes and blood sugar: x2 =14. 83,P =0. 020, r =0. 152; in SAO patients, OR was 1. 925 (95％ CI 1. 392-2. 664) ; in the patients with AT, there was no correlation to blood sugar levels.Association analysis of high blood pressure in stroke subtypes: in AT patients, OR was 2. 874 (95％ CI 1. 957-4. 222) ; in SAO, OR was 1. 609 (95％ CI 1. 100-1. 235). Association analysis of high LDL-C in each subtype: OR in SAO was 1.419 (95％ CI 1.026-1. 962) ;No significant correlation of LDL-C in AT patients, P =0. 929 ; (3) There is significant difference of frequency of abnormal glycometabolism between stroke subtypes: x2 =17. 79 ,P =0. 000; between AT and SAO patients, x2 =0. 024,P =0. 877; between AT or SAO patients to other three subtypes, P ＜ 0. 05. ConclusionsAmong the subtypes of cerebral ischemic stroke by NEW-TOAST classification, AT and SAO are the most common subtypes.All the subtypes have correlation to the high level of blood sugar, and SAO has the highest correlation to blood sugar levels. High blood pressure may affect both large vessels and small vessels, while high LDL-C may mainly affect small vessels.

Application of parallel acquisition technique combined with echo-planar diffusion-weighted imaging technology in the diagnosis of liver micrometastasis for the patients with prooperation of colon cancer / 中国基层医药

Objective To discuss the role of EPI-DWI unite ASSET in the detection of hepatic colorectal micrometastasis. Methods 29 patients with hepatic colorectal metastasis were examined with EPI-DWI unite ASSET and EPI-DWI. Results In a lesion detection analysis,the overall detection rate was 93% (58/63) for ASSET-EPI-DWI,and 81% (51/63) for diffusion-weighted MR imaging. ASSET and EPI-DWI was more sensitive than diffusion-weighted MR imaging(P = 0.01 1). Conclusion ASSET-EPI-DWI is superior to diffusion-weighted MR imaging in the detection of hepatic colorectal micrometastasis.

The comparative study of diffusion-weighted MR imaging with modified sensitivity encoding technique for small hepatocellular carcinoma lesions / 中华放射学杂志

Objective To prospectively evaluate whether DWI with mSENSE(mSENSE-DW1)can help to improve image quality and affect the calculation of lesion's ADC,compared with DWI with conventional phase encoding(conventional DWI)in patients with small HCC lesions.Methods Thirty-two patients with 47 small HCC lesions underwent single-shot spin-echo echo-planar.(SE-EPI)DWI with conventional phase encoding and mSENSE.Three b values of 300,500 and 800 s/mm~2 were used.Image quality and CNR between conventional DWI and mSENSE-DWI group were compared with different b value. Lesion's ADC were also calculated and compared.Matched-pairs Wilcoxon signed rank test and Friedman test were used to test statistical significance.Results The image quality was assessed with a five-point scale.For conventional DWI group,image quality score of 2 was assigned in 5 cases,score of 3 in 24 cases, score of 4 in remaining 3 eases with b=300 s/mm~2,score of 2 in 9 eases,score of 3 in 22 cases,score of 4 in remainingl cases with b=500 s/mm~2,score of 1 in 2 cases,score of 2 in 24 cases,score of 3 in remaining 6 cases with b=800 s/mm~2.For mSENSE-DWI group,image quality score of 3 was assigned in 4 cases,score of 4 in 25 cases,score of 5 in 3 eases with b=300 s/mm~2,score of 3 in 10 cases,score of 4 in 20 cases,score of 5 in remaining 2 cases with b=500 s/mm~2,score of 2 in 7 cases,score of 3 in 23 eases, score of 4 in remaining 2 cases with b=800 s/mm~2.Higher image quality scores were achieved at mSENSE- DWI group than conventional DWI group(Z=-5.578,-5.488,-4.796 respectively,P

A preliminary study of human visual cortex and clinical application by functional magnetic resonance imaging / 中华放射学杂志

Objective This test is focused on functional magnetic resonance imaging(fMRI) of visual cortex by using echo planar imaging(EPI) and blood oxygenation level dependent(BOLD) contrast. Methods 36 normal volunteers and 17 patients with lesions at occipital lobe were included in this test. The echo planar images of the occipital area were acquired at visual stimulation and rest phases. Results The primary visual cortex was located at the bilateral calcarine cortex, which belonged to Brodmann area 17. The functional areas showed displacement due to the mass effect of lesions near calcarine cortex in 3 patients. Conclusion fMRI can be used to study human functional cortex. A preliminary location of visual cortex can be acquired through visual stimulation. The invasion of the intracranial massive lesions to functional areas the disappearance of functional activation. The mass effect of intracranial lesions may lead to deformation or displacement of the near functional areas.

Application of MR diffusion-weighted imaging in the diagnosis of hyperacute cerebral infarction / 中华放射学杂志

Objective To evaluate the accuracy of MR diffusion weighted imaging (DWI) in the diagnosis of hyperacute cerebral infarction. Methods Twenty one patients with onset of strokelike symptoms underwent conventional MRI and DWI within 6 hours. Results DWI indicated cerebral infarction in 16 patients, all of whom had a final diagnosis of acute stroke. DWI was negative in 5 patients, all of whom had a final diagnosis of TIA. The abnormality seen at DWI was confirmed with follow up study. DWI had a sensitivity of 100% and a specificity of 100% in the diagnosis of hyperacute cerebral infarction, and conventional MRI interpretation yielded a sensitivity and specificity of 25% and 100%, respectively. Conclusion DWI is highly accurate in diagnosing hyperacute cerebral infarction and is superior to conventional MRI.

Detection of subarachnoid haemorrhage with gradient echo T_2 ~*sequences / 中华神经科杂志

Objective To measure the sensitivity and specificity of gradient echo T*_2(GRE-T*_2) to subarachnoid haemorrhage (SAH). Methods 12 patients with SAH underwent MRI using T_1WI, T_2WI, FLAIR, GRE-T*_2 sequences and CT as well. Results (1)In the acute-stage of the patients, SAH was seen as an area of high signal intensity as compared with the surrounding cerebrospinal fluid in 66.6% of the cases on T_1-weighted images, and in 100% on FLAIR images; low signal intensities were seen in 50.0% of the cases on T_2-weighted images, and in 100% on GRE-T*_2-weighted images; (2) In the subacute of the patients, SAH was detected on T_1-weighted images (25.0% of cases), FLAIR (25.0%), T_2-weighted images (0), GRE-T*_2-weighted images (100.0%); (3) In the patients with atypical SAH, both CT and FLAIR sequence in MRI were negative for SAH, while lumber acupuncture and GRE-T*_2 had positive findings. Conclusion GRE-T*_2 is the most sensitive sequence of MRI for detecting acute and subacute SAH and has significant advantages over CT in the detection of subacute and atypical SAH.

A Preliminary Results of Acoustic Noise Effect due to Gradient Pulsing in Functional MRI

PURPOSE: In functional MRI(fMRI), the acoustic noise effects of gradient pulsing are analyzed with two different combinations of readout and phase-encoding gradients for sagittal-view images. MATERIALS AND METHODS: Series of sagittal-view EPI images for fMRI obtained from five healthy volunteers. In order to show the effect of gradient pulsing noise, this study was duplicated for the Y readout / Z phase-encoding gradients and the Z readout / Y phase-encoding gradients. The first 7 images were obtained with visual stimulation. This sequential paradigm without and with visual stimulation was repeated 4 times, and was followed by the last 7 images being obtained without visual stimulation. In order to compare the visual cortex activation according to the combination of readout and phase-encoding gradients, the number of activated pixels and the average intensities of the activated pixels were analyzed, where the total activation is defined by multiplying the number of activated pixels by the average intensities of the activated pixels. RESULTS: The experimental results show that the combination of Z readout and Y phase-encoding gradients produce larger visual cortex activation than the combination of Y readout and Z phase-encoding gradients when a sagittal-view fMRI is performed. CONCLUSION: This experiment result represents that visual cortex response can be affected by acoustic noise. Therefore, the combination of the Z readout and Y phase encoding gradients is efficient for sagittal view fMRI because it has less acoustic noise.

Evaluation of brachial plexus with MR echo planar imaging: initial experience / 中华放射学杂志

Objective To determine the optimal sequences and scan parameters of Brachial Plexus MRI.Methods Eighteen volunteers were underwent conventional MRI and echo planar imaging scanning. The images acquired were compared with the standard anatomical pictures. Results Ventral rami, ganglion, trunks, cords and some peripheral nerves of brachial plexus were demonstrated very well by echo planar imaging with the post-processing techniques such as MIP, thin slice MIP and MPR.In 18/18 cases the postganglions on both sides and 17/18 cases the preganglions of brachial plexus on both sides could be visualized in EPI pre-processed and post-processed images.Conclusion Echo planar imaging is an effective technique of accurately displaying brachial plexus and adjacent structures. It has potential value in the diagnosis and treatment of brachial plexus diseases. It is also a potential technique to demonstrate other peripheral nerves accurately.