New Findings, Classification and Long-Term Follow-Up Study Based on MRI Characterization of Brainstem Encephalitis Induced by Enterovirus 71.
ABSTRACT: To report the diversity of MRI features of brainstem encephalitis (BE) induced by Enterovirus 71. This is supported by implementation and testing of our new classification scheme in order to improve the diagnostic level on this specific disease.Neuroimaging of 91 pediatric patients who got EV71 related BE were hospitalized between March, 2010 to October, 2012, were analyzed retrospectively. All patients underwent pre- and post-contrast MRI scan. Thereafter, 31 patients were randomly called back for follow-up MRI study during December 2013 to August 2014. The MRI signal patterns of BE primary lesion were analyzed and classified according to MR signal alteration at various disease stages. Findings in fatal and non-fatal cases were compared, and according to the MRI scan time point during the course of this disease, the patients' conditions were classified as 1) acute stage, 2) convalescence stage, 3) post mortem stage, and 4) long term follow-up study.103 patients were identified. 11 patients did not undergo MRI, as they died within 48 hours. One patient died on 14th day without MR imaging. 2 patients had postmortem MRI. Medical records and imaging were reviewed in the 91 patients, aged 4 months to 12 years, and two cadavers who have had MRI scan. At acute stage: the most frequent pattern (40 patients) was foci of prolonged T1 and T2 signal, with (15) or without (25) contrast enhancement. We observed a novel pattern in 4 patients having foci of low signal intensity on T2WI, with contrast enhancement. Another pattern in 10 patients having foci of contrast enhancement without abnormalities in T1WI or T2WI weighted images. Based on 2 cases, the entire medulla and pons had prolonged T1 and T2 signal, and 2 of our postmortem cases demonstrated the same pattern. At convalescence stage, the pattern observed in 4 patients was foci of prolonged T1 and T2 signal without contrast enhancement. Follow-up MR study of 31 cases showed normal in 26 cases, and demonstrated foci of prolonged T1 and T2 signal with hyper-intensity on FLAIR in 3 cases, or of prolonged T1 and T2 signal with hypo-intensity on FLAIR in 2 cases. Most importantly, MR findings of each case were thoroughly investigated and classified according to phases and MRI signal alteration.This study has provided enhanced and useful information for the MRI features of BE induced by EV71, apart from common practice established by previous reports. In addition, a classification scheme that summarizes all types of features based on the MRI signal at the four different stages of the disease would be helpful to improve the diagnostic level.
Project description:Liver tumors are common and imaging methods, particularly magnetic resonance imaging (MRI), play an important role in their non-invasive diagnosis. Previous studies have shown that detection of liver tumors can be improved by injection of two different MR contrast agents. Here, we developed a new contrast agent, Gd-manganese-doped magnetism-engineered iron oxide (Gd-MnMEIO), with enhancement effects on both T1- and T2-weighted MR images of the liver. A 3.0T clinical MR scanner equipped with transmit/receiver coil for mouse was used to obtain both T1-weighted spoiled gradient-echo and T2-weighted fast spin-echo axial images of the liver before and after intravenous contrast agent injection into Balb/c mice with and without tumors. After pre-contrast scanning, six mice per group were intravenously injected with 0.1 mmol/kg Gd-MnMEIO, or the control agents, i.e., Gd-DTPA or SPIO. The scanning time points for T1-weighted images were 0.5, 5, 10, 15, 20, 25, and 30 min after contrast administration. The post-enhanced T2-weighted images were then acquired immediately after T1-weighted acquisition. We found that T1-weighted images were positively enhanced by both Gd-DTPA and Gd-MnMEIO and negatively enhanced by SPIO. The enhancement by both Gd-DTPA and Gd-MnMEIO peaked at 0.5 min and gradually declined thereafter. Gd-MnMEIO (like Gd-DTPA) enhanced T1-weighted images and (like SPIO) T2-weighted images. Marked vascular enhancement was clearly visible on dynamic T1-weighted images with Gd-MnMEIO. In addition, the T2 signal was significantly decreased at 30 min after administration of Gd-MnMEIO. Whereas the effects of Gd-MnMEIO and SPIO on T2-weighted images were similar (p = 0.5824), those of Gd-MnMEIO and Gd-DTPA differed, with Gd-MnMEIO having a significant T2 contrast effect (p = 0.0086). Our study confirms the feasibility of synthesizing an MR contrast agent with both T1 and T2 shortening effects and using such an agent in vivo. This agent enables tumor detection and characterization in single liver MRI sections.
Project description:OBJECTIVES:To associate MRI textural analysis (MRTA) with MRI and histological Crohn's disease (CD) activity. METHODS:Sixteen patients (mean age 39.5 years, 9 male) undergoing MR enterography before ileal resection were retrospectively analysed. Thirty-six small (?3 mm) ROIs were placed on T2-weighted images and location-matched histological acute inflammatory scores (AIS) measured. MRI activity (mural thickness, T2 signal, T1 enhancement) (CDA) was scored in large ROIs. MRTA features (mean, standard deviation, mean of positive pixels (MPP), entropy, kurtosis, skewness) were extracted using a filtration histogram technique. Spatial scale filtration (SSF) ranged from 2 to 5 mm. Regression (linear/logistic) tested associations between MRTA and AIS (small ROIs), and CDA/constituent parameters (large ROIs). RESULTS:Skewness (SSF?=?2 mm) was associated with AIS [regression coefficient (rc) 4.27, p?=?0.02]. Of 120 large ROI analyses (for each MRI, MRTA feature and SSF), 15 were significant. Entropy (SSF?=?2, 3 mm) and kurtosis (SSF?=?3 mm) were associated with CDA (rc 0.9, 1.0, -0.45, p?=?0.006-0.01). Entropy and mean (SSF?=?2-4 mm) were associated with T2 signal [odds ratio (OR) 2.32-3.16, p?=?0.02-0.004], [OR 1.22-1.28, p?=?0.03-0.04]. MPP (SSF?=?2 mm) was associated with mural thickness (OR 0.91, p?=?0.04). Kurtosis (SSF?=?3 mm), standard deviation (SSF?=?5 mm) were associated with decreased T1 enhancement (OR 0.59, 0.42, p?=?0.004, 0.007). CONCLUSIONS:MRTA features may be associated with CD activity. KEY POINTS:• MR texture analysis features may be associated with Crohn's disease histological activity. • Texture analysis features may correlate with MR-dependent Crohn's disease activity scores. • The utility of MR texture analysis in Crohn's disease merits further investigation.
Project description:BACKGROUND:To investigate the magnetic resonance imaging (MRI) features of orbital Langerhans cell histiocytosis (LCH) to improve diagnostic accuracy. METHODS:We retrospectively reviewed clinical manifestations and MRI findings of 23 patients with histopathology-confirmed LCH of the orbit. The findings were evaluated for the following: (a) symptoms, (b) disease duration, (c) location, (d) configuration, (e) margin, (f) MR imaging signal intensity and enhanced performance. RESULTS:Eighteen patients (78%) in our series were male, only five (22%) patients were female, and the mean age at presentation was 6.3?years. The common symptoms include swollen eyelids, exophthalmos, and a palpable mass. Fourteen patients presented with swollen eyelids and/or exophthalmos. Twenty-two cases involved unilateral orbits, and one case involved bilateral orbits. In our study, there was one patient with cough and expectoration, and one patient with polydipsia and polyuria. Lesions were located in the superior or superlateral orbital roof of seventeen patients (74%). Lesions formed masses or irregular shapes. The 12 out of 23 (52.2%) cases appeared heterogeneous isointense and 10 out of 23 (43.5%) cases showed iso-hypointense on T1-weighted imaging, there were 15 out of 23 (65.2%) cases showed hyper-hypointense mixed signals on T2-weighted imaging. 7 cases found patchy hyperintense signal on T1WI, and 11 cases showed markedly hyperintense signal near the edge of lesions on T2WI. After enhancement, 21 out of 23 (91.3%) cases lesions presented marked enhancement at the edges and the surrounding tissues, and with heterogeneous obvious enhancement of the lesion center. Besides, four cases lesions were surrounded by a low circular signal. CONCLUSION:There were several characteristics MRI features that can provide crucial information for clinicians and improve our understanding and the diagnostic accuracy of the orbital LCH.
Project description:The aim of this study was to analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of dermatofibrosarcoma protuberans (DFSP), with a view to improving the diagnosis of this kind of tumor. A total of 27 cases of histopathologically confirmed DFSP were analyzed retrospectively. Of these, 18 patients underwent a CT scan and 9 patients underwent an MRI. All patients underwent unenhanced and contrast-enhanced examinations; 1 patient underwent multiphrase CT enhancement examination. Imaging characteristics, including location, shape, size, number, edge, and attenuation or intensity of each lesion, both unenhanced and contrast enhanced, were analyzed. Of the 27 cases, 24 were solitary, 2 had 2 nodules, and 1 had multiple confluent tumors. The lesion with multiple confluent tumors was ill defined and irregular; the other lesions were oval or round, well-defined nodules or masses. The unenhanced CT images showed 19 homogenous isodense lesions. There was no calcification in any of the patients. The contrast-enhanced CT images showed intermediate and marked nonhomogeneous enhancement in 13 lesions, intermediate homogeneous enhancement in 4 lesions, and a mild heterogeneous enhancement in 2 lesions. MR T1-weighted images revealed 1 ill-defined and 9 well-defined homogeneous isointense lesions. T2-weighted images showed homogeneous hyperintensity to the muscles in 6 lesions, 3 mild hyperintense lesions with hypointense lesions, and 1 mixed, mild hyperintense and isointense lesion. Contrast-enhanced T1-weighted images demonstrated intermediate and marked nonhomogeneous enhancement in 9 lesions and intermediate homogeneous enhancement in 1 lesion. DFSP is characterized by a subcutaneous well-defined soft tissue nodule or mass on plain CT/MR scans, and shows intermediate-to-marked enhancement on contrast-enhanced CT/MR scans. The imaging findings for DFSP are nonspecific, but may help to define the diagnosis in an appropriate clinical setting.
Project description:An update of the 2010 published ESUR recommendations of MRI of the sonographically indeterminate adnexal mass integrating functional techniques is provided. An algorithmic approach using sagittal T2 and a set of transaxial T1 and T2WI allows categorization of adnexal masses in one of the following three types according to its predominant signal characteristics. T1 'bright' masses due to fat or blood content can be simply and effectively determined using a combination of T1W, T2W and FST1W imaging. When there is concern for a solid component within such a mass, it requires additional assessment as for a complex cystic or cystic-solid mass. For low T2 solid adnexal masses, DWI is now recommended. Such masses with low DWI signal on high b value image (e.g. > b 1000 s/mm2) can be regarded as benign. Any other solid adnexal mass, displaying intermediate or high DWI signal, requires further assessment by contrast-enhanced (CE)T1W imaging, ideally with DCE MR, where a type 3 curve is highly predictive of malignancy. For complex cystic or cystic-solid masses, both DWI and CET1W-preferably DCE MRI-is recommended. Characteristic enhancement curves of solid components can discriminate between lesions that are highly likely malignant and highly likely benign.• MRI is a useful complementary imaging technique for assessing sonographically indeterminate masses. • Categorization allows confident diagnosis in the majority of adnexal masses. • Type 3 contrast enhancement curve is a strong indicator of malignancy. • In sonographically indeterminate masses, complementary MRI assists in triaging patient management.
Project description:We aimed to investigate the effectiveness of ferritin as a contrast agent and a potential reporter gene for tracking tumor cells or macrophages in mouse cancer models.Adenoviral human ferritin heavy chain (Ad-hFTH) was administrated to orthotopic glioma models and subcutaneous colon cancer mouse models using U87MG and HCT116 cells, respectively. Brain MR images were acquired before and daily for up to 6 days after the intracranial injection of Ad-hFTH. In the HCT116 tumor model, MR examinations were performed before and at 6, 24, and 48 h after intratumoral injection of Ad-hFTH, as well as before and every two days after intravenous injection of ferritin-labeled macrophages. The contrast effect of ferritin in vitro was measured by MR imaging of cell pellets. MRI examinations using a 7T MR scanner comprised a T1-weighted (T1w) spin-echo sequence, T2-weighted (T2w) relaxation enhancement sequence, and T2*-weighted (T2*w) fast low angle shot sequence.Cell pellet imaging of Ad-hFTH in vitro showed a strong negatively enhanced contrast in T2w and T2*w images, presenting with darker signal intensity in high concentrations of Fe. T2w images of glioma and subcutaneous HCT116 tumor models showed a dark signal intensity around or within the Ad-hFTH tumor, which was distinct with time and apparent in T2*w images. After injection of ferritin-labeled macrophages, negative contrast enhancement was identified within the tumor.Ferritin could be a good candidate as an endogenous MR contrast agent and a potential reporter gene that is capable of maintaining cell labeling stability and cellular safety.
Project description:Disruption of the BBB in MS is associated with the development of new lesions and clinical relapses and signifies the presence of active inflammation. It is most commonly detected as enhancement on MR imaging performed with contrast agents that are costly and occasionally toxic. We investigated whether the BBB status in white matter lesions may be indirectly ascertained via examination of features on T1- and T2-weighted images obtained before the injection of a contrast agent.We considered 93 brain MR imaging studies on 16 patients that included T1-, T2-, and T2-weighted FLAIR images and predicted voxel wise enhancement after intravenous injection of a gadolinium chelate. We then used these voxel-level predictions to determine the presence or absence of abnormal enhancement anywhere in the brain.On a voxel-by-voxel basis, enhancement can be predicted by using contrast-free measures with an AUC of 0.83 (95% CI, 0.80-0.87). At the whole-brain level, enhancement can be predicted with an AUC of 0.72 (95% CI, 0.62-0.82).In many cases, breakdown of the BBB in acute MS lesions may be inferred without the need to inject an MR imaging contrast agent. The inference relies on intrinsic properties of tissue damage in acute lesions. Although contrast studies are more accurate, they may sometimes be unnecessary.
Project description:We present a method to efficiently separate signal in magnetic resonance imaging (MRI) into a base signal S0, representing the mainly T1-weighted component without T2*-relaxation, and its T2*-weighted counterpart by the rapid acquisition of multiple contrasts for advanced pharmacokinetic modelling. This is achieved by incorporating simultaneous multislice (SMS) imaging into a multi-contrast, segmented echo planar imaging (EPI) sequence to allow extended spatial coverage, which covers larger body regions without time penalty. Simultaneous acquisition of four slices was combined with segmented EPI for fast imaging with three gradient echo times in a preclinical perfusion study. Six female domestic pigs, German-landrace or hybrid-form, were scanned for 11 minutes respectively during administration of gadolinium-based contrast agent. Influences of reconstruction methods and training data were investigated. The separation into T1- and T2*-dependent signal contributions was achieved by fitting a standard analytical model to the acquired multi-echo data. The application of SMS yielded sufficient temporal resolution for the detection of the arterial input function in major vessels, while anatomical coverage allowed perfusion analysis of muscle tissue. The separation of the MR signal into T1- and T2*-dependent components allowed the correction of susceptibility related changes. We demonstrate a novel sequence for dynamic contrast-enhanced MRI that meets the requirements of temporal resolution (?t < 1.5 s) and image quality. The incorporation of SMS into multi-contrast, segmented EPI can overcome existing limitations of dynamic contrast enhancement and dynamic susceptibility contrast methods, when applied separately. The new approach allows both techniques to be combined in a single acquisition with a large spatial coverage.
Project description:To determine the evolution of prostatic multi-parametric magnetic resonance imaging (mp-MRI) signal following transrectal ultrasound (TRUS)-guided biopsy.Local ethical permission and informed written consent was obtained from all the participants (n=14, aged 43-69, mean 64 years). Patients with a clinical suspicion of prostate cancer (PSA range 2.2-11.7, mean 6.2) and a negative (PIRAD 1-2/5) pre-biopsy mp-MRI (pre-contrast T1, T2, diffusion-weighted and dynamic-contrast-enhanced MRI) who underwent 10-core TRUS-guided biopsy were recruited for additional mp-MRI examinations performed at 1, 2 and 6 months post biopsy. We quantified mp-MRI peripheral zone (PZ) and transition zone (TZ) normalized T2 signal intensity (nT2-SI); T1 relaxation time (T10); diffusion-weighted MRI, apparent diffusion coefficient (ADC); dynamic contrast-enhanced MRI, maximum enhancement (ME); slope of enhancement (SoE) and area-under-the-contrast-enhancement-curve at 120 s (AUC120). Significant changes in mp-MRI parameters were identified by analysis of variance with Dunnett's post testing.Diffuse signal changes were observed post-biopsy throughout the PZ. No significant signal change occurred following biopsy within the TZ. Left and right PZ mean nT2-SI (left PZ: 5.73, 5.16, 4.90 and 5.12; right PZ: 5.80, 5.10, 4.84 and 5.05 at pre-biopsy, 1, 2 and 6 months post biopsy, respectively) and mean T10 (left PZ: 1.02, 0.67, 0.78, 0.85; right PZ: 1.29, 0.64, 0.78, 0.87 at pre-biopsy, 1, 2 and 6 months post biopsy, respectively) were reduced significantly (P<0.05) from pre-biopsy values for up to 6 months post biopsy. Significant changes (P<0.05) of PZ-ME and AUC120 were observed at 1 month but resolved by 2 months post biopsy. PZ ADC did not change significantly following biopsy (P=0.23-1.0). There was no significant change of any TZ mp-MRI parameter at any time point following biopsy (P=0.1-1.0).Significant PZ (but not TZ) T2 signal changes persist up to 6 months post biopsy, whereas PZ and TZ ADC is not significantly altered as early as 1 month post biopsy. Caution must be exercised when interpreting T1- and T2-weighted imaging early post biopsy, whereas ADC images are more likely to maintain clinical efficacy.
Project description:To minimize feature loss in T1- and T2-weighted MRI by merging multiple MR images acquired at different TR and TE to generate an image with increased dynamic range.High Dynamic Range (HDR) processing techniques from the field of photography were applied to a series of acquired MR images. Specifically, a method to parameterize the algorithm for MRI data was developed and tested. T1- and T2-weighted images of a number of contrast agent phantoms and a live mouse were acquired with varying TR and TE parameters. The images were computationally merged to produce HDR-MR images. All acquisitions were performed on a 7.05 T Bruker PharmaScan with a multi-echo spin echo pulse sequence.HDR-MRI delineated bright and dark features that were either saturated or indistinguishable from background in standard T1- and T2-weighted MRI. The increased dynamic range preserved intensity gradation over a larger range of T1 and T2 in phantoms and revealed more anatomical features in vivo.We have developed and tested a method to apply HDR processing to MR images. The increased dynamic range of HDR-MR images as compared to standard T1- and T2-weighted images minimizes feature loss caused by magnetization recovery or low SNR.