Conventional MRI Scans Research Articles

Measuring in vivo cerebral maturation using age-related T2 relaxation times at 3 T

ObjectiveTo examine age-related changes in T2 relaxation times during infancy and childhood in order to assess T2 values obtained from routine MRI as a biomarker. MethodsFrom our pool of clinical pediatric MRI examinations at 3T all patients with normal conventional MRI scans were retrospectively selected. Depending on their clinical findings the identified 99 patients (0–199months) were divided into 43 healthy controls and 56 diseased children with various clinical abnormalities (developmental delay, epilepsy, prematurity, and deafness). T2 maps based on routinely performed triple echo turbo spin echo sequences were created. T2 values were measured in 22 brain regions to determine age-related changes. We also investigated whether such changes differ between healthy and diseased children. ResultsAge significantly reduced T2 relaxation times across all regions (p<0.05), but health status had no impact. With increasing age, T2 values decreased continuously, with declines faster over the first 10months and slower thereafter. Early rapid and later slow decline was similar in healthy and diseased groups. ConclusionsUsing T2 maps based on clinical MRI data we could determine age-related T2 relaxation times in 22 brain regions during infancy and childhood. Our data have relevance for future investigator independent T2 relaxation time measurements in determining whether T2 values are within the normal range or should be considered as potentially pathologic.

Dosimetric evaluation of synthetic CT for magnetic resonance-only based radiotherapy planning of lung cancer

BackgroundInterest in MR-only treatment planning for radiation therapy is growing rapidly with the emergence of integrated MRI/linear accelerator technology. The purpose of this study was to evaluate the feasibility of using synthetic CT images generated from conventional Dixon-based MRI scans for radiation treatment planning of lung cancer.MethodsEleven patients who underwent whole-body PET/MR imaging following a PET/CT exam were randomly selected from an ongoing prospective IRB-approved study. Attenuation maps derived from the Dixon MR Images and atlas-based method was used to create CT data (synCT). Treatment planning for radiation treatment of lung cancer was optimized on the synCT and subsequently copied to the registered CT (planCT) for dose calculation. Planning target volumes (PTVs) with three sizes and four different locations in the lung were planned for irradiation. The dose-volume metrics comparison and 3D gamma analysis were performed to assess agreement between the synCT and CT calculated dose distributions.ResultsMean differences between PTV doses on synCT and CT across all the plans were −0.1% ± 0.4%, 0.1% ± 0.5%, and 0.4% ± 0.5% for D95, D98 and D100, respectively. Difference in dose between the two datasets for organs at risk (OARs) had average differences of −0.14 ± 0.07 Gy, 0.0% ± 0.1%, and −0.1% ± 0.2% for maximum spinal cord, lung V20, and heart V40 respectively. In patient groups based on tumor size and location, no significant differences were observed in the PTV and OARs dose-volume metrics (p > 0.05), except for the maximum spinal-cord dose when the target volumes were located at the lung apex (p = 0.001). Gamma analysis revealed a pass rate of 99.3% ± 1.1% for 2%/2 mm (dose difference/distance to agreement) acceptance criteria in every plan.ConclusionsThe synCT generated from Dixon-based MRI allows for dose calculation of comparable accuracy to the standard CT for lung cancer treatment planning. The dosimetric agreement between synCT and CT calculated doses warrants further development of a MR-only workflow for radiotherapy of lung cancer.

Dynamic contrast-enhanced MRI in the early diagnosis of brucella spondylitis

Objective To explore the value of dynamic contrast-enhanced (DCE). MRI in the early diagnosis of brucellosis spondylitis. Methods Fifty-six patients (24 female and 32 male) with Brucellosis with average age of (49±3) years were retrospectively analyzed. Inclusion criteria: The patients with clinically diagnosed brinell coli spondylitis, drops of serum agglutination test degree 1∶100>(++), Hu>red plate agglutination test (++), enzyme-linked immunosorbent assay to detect specific antibody IgG/IgM (+). Exclusion criteria: Pregnant and lactating women, patients with MRI examination contraindications and spinal tuberculosis, myeloma or other spinal disease, patients with the cervical, thoracic and lumbar 5 vertebral body involvement. The patients were classified into early lesion group and lesion group. Early lesion group was defined as low back pain less than a month, enzyme-linked immunosorbent assay positive IgM and negative IgG results, and no abnormality in conventional MR imaging, while lesion group was defined as low back pain for longer than 3 months, enzyme-linked immunosorbent assay positive IgG and negative IgM and marked lesion in conventional MR imaging. All the patients conducted with conventional MRI and DCE-MRI scan. The differences of the Ktrans, Kep, Ve and Vp between the vertebral lesions, early lesions of vertebral body and normal tissues were measured and compared. Results The values of Ktrans, Kep, Ve and Vp were significantly different between the vertebral lesions [(0.856±0.539) ml/min, (1.482±0.711) ml/min, 0.542±0.267, 0.034±0.017] and normal tissues [(0.315±0.298) ml/min, (0.713±0.548) ml/min, 0.358±0.259, 0.056±0.03] (all P 0.05). Conclusion DCE-MRI quantitative analysis plays a role in the early diagnosis of the brucella spondylitis. Key words: Spondylitis; Magnetic resonance imaging; Early diagnosis; Brucella

The value of vessel size imaging of microvasculatures in grading of oligodendroglioma

Objective To investigate the value of vessel size index(VSI) in grading oligodendroglioma by vessel size imaging technique. Methods Twenty-four histologically confirmed oligodendroglioma cases were enrolled (13 gradeⅡand 11 gradeⅢ) . All patients underwent conventional MRI scanning, followed by multi gradient-echo spin-echo sequence from dynamic susceptibility contrast perfusion to generate VSI maps. Region of interests were contoured on VSI color maps to obtain hot-spot value of mean VSI of microvasculature (VSImean) and maximum VSI of microvasculature (VSImax). Paraffin sections of each case was stained with CD34 to acquire microvascular caliber (VShis). Pearson correlation analysis was used to evaluate the correlation between VSImean, VSImax and VShis respectively. Mann-Whitney U test was used to compare VSImean, VSImax and VShis between grade Ⅱ and Ⅲ oligodendrogliomas. ROC analysis was performed to assess the effectiveness of VSImean, VSImax and VShis in grading oligodendrogliomas. Results Both VSImean and VSImax were strongly correlated with VShis (r=0.738, 0.705,P<0.05). For gradeⅡand Ⅲ oligodendrogliomas, VSImean were 38.93(17.96 to 81.18)μm and 91.49(36.94 to 144.68)μm, VSImax were 45.12(22.30 to 89.65)μm and 121.19(57.29 to 164.00)μm, VShis were 8.51(5.25 to 12.76)μm and 11.03(7.59 to 21.96)μm respectively. VSImean, VSImax, and VShis showed significant difference (Z=-3.505,-3.911, -2.729,P<0.05) between grade Ⅱ and Ⅲ oligodendrogliomas. ROC analysis revealed that the optimal cutoff value, sensitivity, specificity and AUC of VSImean was 52.58 μm, 90.91%, 92.31%, 0.923 respectively, 81.18μm, 90.91%, 100.00%, 0.972 for VSImax, and 9.01μm, 90.00%, 84.62%, 0.838 for VShis respectively. Conclusions Vessel size imaging derived VSI correlated well with histopathology. It could provide valuable information in the pre-operative grading of oligodendroglioma.

Altered states of consciousness in epilepsy: a DTI study of the brain

Background: A disturbance in the level of consciousness is a classical clinical sign of several seizure types. Recent studies have shown that altered states of consciousness in seizures are associated with structural and functional changes of several brain regions. Prominent among these are the thalamus, the brain stem and the default mode network, which is part of the consciousness system. Our study used diffusion tensor imaging (DTI) to evaluate these brain regions in patients with three different types of epilepsies that are associated with altered consciousness: complex partial seizures (CPS), primary generalized tonic–clonic seizures (PGTCS) or secondary generalized tonic–clonic seizures (SGTCS). Additionally, this study further explores the probable mechanisms underlying impairment of consciousness in seizures. Materials and methods: Conventional MRI and DTI scanning were performed in 51 patients with epilepsy and 51 healthy volunteers. The epilepsy group was in turn subdivided into three subgroups: CPS, PGTCS or SGTCS. Each subgroup comprised 17 patients. Each subject involved in the study underwent a DTI evaluation of the brain to measure the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of nine regions of interest: the postero-superior portion of midbrain, the bilateral dorsal thalamus, the bilateral precuneus/posterior cingulate, the bilateral medial pre-frontal gyri and the bilateral supramarginalgyri. The statistical significance of the measured ADC and FA values between the experimental and control groups was analysed using the paired t-test, and one-way analysis of variance was performed for a comparative analysis between the three subgroups. Results: Statistically significantly higher ADC values ( p < 0.01) were observed in the bilateral dorsal thalamus and postero-superior aspect of the midbrain in the three patient subgroups than in the control group. There were no significant changes in the ADC values ( p > 0.05) in the bilateral precuneus/posterior cingulate, bilateral medial pre-frontal gyri or bilateral supramarginalgyri in the experimental group. Among the three patient subgroups and the ADC values of corresponding brain regions, there were no statistically significant changes. Statistically significantly lower FA values ( p < 0.05) were observed in the bilateral dorsal thalamus of the patients in the three subgroups than in the control group. Significantly lowered FA values from the postero-superior aspect of the mid brain ( p < 0.01) were observed in patients with PGTCS compared with the control group. There were no significant changes in the FA values ( p > 0.05) from the bilateral precuneus/posterior cingulate, bilateral medial frontal gyri or bilateral supramarginalgyri in the experimental group. Among the three patient subgroups and the FA values of the corresponding brain regions, there were no statistically significant changes. Conclusion: In epileptic patients with CPS, PGTCS or SGTCS, there seems to be a long-lasting neuronal dysfunction of the bilateral dorsal thalamus and postero-superior aspect of the midbrain. The thalamus and upper brain stem are likely to play a key role in epileptic patients with impaired consciousness.

The correlation between cerebral MRI characteristics of posterior reversible encephalopathy syndrome and serum levels of PlGF, sEng in patients with pre-eclampsia

Objective: To investigate the MRI characteristics of posterior reversible encephalopathy syndrome (PRES) in patients with pre-eclampsia(PE) and its correlation with serum placental growth factor (PlGF), soluble endoglin (sEng) and sEng/PlGF ratio. Methods: 34 patients with PE who were admitted to Guangdong Women and Children Hospital from September 2013 to March 2014 were studied retrospectively.13 cases had PRES and 21 cases had normal cerebral MRI. All patients underwent conventional MRI and DWI scanning. The score of brain edema (SBE) were calculated. PlGF, sEng concentrations were measured with ELISA. The levels of PlGF, sEng and sEng/PlGF were compared between the PRES group and the normal MRI groups. The correlation of sEng/PIGF ratio and SBE were studied as well. Results: The PlGF in the PRSE group was (231.4±66.8) ng/L, and in normal cerebral MRI group was (333.6±37.5) ng/L (t= 5.61, P<0.05). The sEng in the PRSE group was (5 256.2±879.6) ng/L, in normal cerebral MRI group was (3 955.6±537.7) ng/L (t=6.53, P<0.01).The sEng/PlGF in the PRSE group was (26.0±10.0) , and in normal cerebral MRI group was (11.9±1.6; t=8.41, P<0.01) , with the cut-off value of 20.0. The sensitivity was 81.8% and the specificity was 85.0%.There was no statistically significant correlation between PlGF, sEng and SBE (P>0.05).There was a positive correlation between the sEng/PlGF ratio and SBE (P>0.05). Conclusion: The value of sEng/PlGF ratio was correlated with brain edema score in PE. The serum sEng/PlGF ratio may be used as a reference for prediction of PRES.

P07.17 Automated grade prediction of glioma patients based on magnetic resonance imaging and a random forests approach

An automated brain tumour classification method is presented which is able to distinguish between low-grade and high-grade glioma on conventional MRI scans. Per patient, 208 quantitative features are extracted from a manually annotated brain tumour database of 274 patients. These features were then used to train a Random Forests classification algorithm. We achieved a high-grade prediction sensitivity of 85.5% and specificity of 83.3%, with a global accuracy of 85.0%.

SU-F-R-02: Imaging-Genomics for Predicting GBM Molecular Subclasses and Survival

Purpose: Glioblastoma (GBM) is the most common and fatal primary intracranial neoplasm. GBM is categorized into five sub-classes (classical, G-CIMP, mesenchymal, proneural and neural) that can only be determined by an invasive brain biopsy followed by RNA and DNA methylation profiling. The goal of this study is to develop imaging features extracted from conventional MRI scans and an ensemble-classification method as a potential noninvasive method to predict the five molecular sub-classes and 12-month survival status. Methods: Tumors are segmented into 4 cardinal sub-volumes that are enhancing, non-enhancing, necrosis, and edema by BraTuma software and post-manual modification. After intensity normalization, mean, standard deviation, skewness, and kurtosis of voxel intensities and normalized volume of each of the 4 sub-volumes are calculated. The first four features are extracted from three different modalities (T1 pre & post contrast and T2 FLAIR) and the tumor texture is quantified. A feature selection phase (wrapper algorithm) is preceded the classification stage. Ensembles of binary classifiers with one versus rest strategy, along with a separate binary classifier are employed respectively for molecular classification and survival status. Two different binary classifiers are tested (SVM and K* IBL) and their confidences are used for tie-breaking technique. Results: With the select combination of features of the MRI modalities, the ROC area and accuracy of the prediction are 0.750 and 95% for classical, 1.000 and 100% for G-CIMP, 0.719 and 85% for mesenchymal, 0.875 and 95% for neural, 0.922 and 95% for proneural, and 0.990 and 95% for survival status respectively. Conclusion: The study proposes a set of three-dimensional and rotation invariant imaging features that represent texture and volumetric characteristics of GBM tumors. The results show the select features are predictive for five molecular sub-classes and survival status in GBM. These results indicate the feasibility of obviating the biopsy for obtaining genomic information of tumor.

Assessment of brainstem reflexes improves the diagnostic sensitivity of multimodal evoked potentials, MRI and clinical testing in the investigation of brainstem function in multiple sclerosis

Background Brainstem (BS) functions are conventionally studied by multimodal evoked potential (EP) recordings, MRI and clinical examination (CLIN). In Multiple Sclerosis (MS), increasing evidence accounts for a BS involvement, often undetected by standard testing. Recently, brainstem reflexes (BSRs) have drawn attention in evaluating BS dysfunction in MS especially the vestibulocollic (VCR) and vestibuloocular reflexes. In contrast, the vestibulomasseteric (VMR), acousticmasseteric (AMR) and trigeminocollic (TCR) reflexes have never been studied systematically in MS. Aims: to investigate whether the diagnostic sensitivity of CLIN, EPs and MRI can be improved adding the assessment of VMR, AMR, TCR and VCR either as single reflexes or in a 4-BSR battery. Methods The 4-BSR battery was recorded in 60 patients (33.3 ± 8.3 yrs) with relapsing-remitting MS (illness duration 8.2 ± 6.4 yrs). EP set included standard BAEPs, median and tibial SEPs Conventional MRI scans were focused on the BS lesion load. Group differences and correlations between variables were analysed with Mann–Whitney U test and Mc Nemar test. Results Distribution of BSR and EP abnormality frequencies in MS was: VMR 62.1%, AMR 55.1%, TCR 58.6%, VCR 25.9%; BAEPs 37.3%, median SEPs 60.3% and tibial SEPs 58.6%. Overall, BS dysfunction was detected as follows: BSRs 86.9%, EPs 82.7%, MRI 71.7%, CLIN 37.7%. While the performance of BSRs and EPs, taken separately, was not significantly higher than that of combined MRI/CLIN testing (70%), the paired use of BSRs/EPs had a sensitivity of 93.3%, which was significantly superior (p = 0.007), in a subset of patients with a disease duration ⩽6.4 yrs. Conclusions BSRs revealed brainstem lesions otherwise undetected by CLIN and MRI, thus providing additional evidence of BS dysfunction in MS. Noteworthy, BSRs could effectively complement the usual EP testing in early detection of clinically and radiologically silent lesions. This may encourage EPs/BSRs paired use in newly diagnosed. FISM GRANTS 2008/R/9 and 2011/R/17.

Role of Diffusion Weighted Imaging in Differentiating Benign from Malignant Head and Neck Tumors

Head and neck mass is considered to be a relatively common finding in adult and pediatric patients and can present a difficult diagnostic challenge. Differentiation of benign head and neck tumors from malignant lesions are important for treatment strategy as well as for predicting prognosis of malignant tumors. The aim of this work is to review the role of diffusion MRI scan in differentiation between benign and malignant head and neck masses This study was performed on 72 patients (30 men and 42 women aged from 13 years to 85 years, mean age of 51 years) with head and neck mass, in the period from September 2012 until May 2014. We found that DWI is a reliable noninvasive imaging tool to help in differentiation between malignant and benign head and neck lesions and also to identify the tumor-free soft tissue in patients with head and neck neoplasms. It could be performed with conventional MR systems in few minutes time, Further studies on larger number of patients is required to assess if such a technique should be implemented routinely with conventional MRI scan.

The use of dynamic O-(2-18F-fluoroethyl)-l-tyrosine PET in the diagnosis of patients with progressive and recurrent glioma.

We evaluated the diagnostic value of static and dynamic O-(2-[(18)F]fluoroethyl)-L-tyrosine ((18)F-FET) PET parameters in patients with progressive or recurrent glioma. We retrospectively analyzed 132 dynamic (18)F-FET PET and conventional MRI scans of 124 glioma patients (primary World Health Organization grade II, n = 55; grade III, n = 19; grade IV, n = 50; mean age, 52 ± 14 y). Patients had been referred for PET assessment with clinical signs and/or MRI findings suggestive of tumor progression or recurrence based on Response Assessment in Neuro-Oncology criteria. Maximum and mean tumor/brain ratios of (18)F-FET uptake were determined (20-40 min post-injection) as well as tracer uptake kinetics (ie, time to peak and patterns of the time-activity curves). Diagnoses were confirmed histologically (95%) or by clinical follow-up (5%). Diagnostic accuracies of PET and MR parameters for the detection of tumor progression or recurrence were evaluated by receiver operating characteristic analyses/chi-square test. Tumor progression or recurrence could be diagnosed in 121 of 132 cases (92%). MRI and (18)F-FET PET findings were concordant in 84% and discordant in 16%. Compared with the diagnostic accuracy of conventional MRI to diagnose tumor progression or recurrence (85%), a higher accuracy (93%) was achieved by (18)F-FET PET when a mean tumor/brain ratio ≥2.0 or time to peak <45 min was present (sensitivity, 93%; specificity, 100%; accuracy, 93%; positive predictive value, 100%; P < .001). Static and dynamic (18)F-FET PET parameters differentiate progressive or recurrent glioma from treatment-related nonneoplastic changes with higher accuracy than conventional MRI.

High-Field iMRI in transsphenoidal pituitary adenoma surgery with special respect to typical localization of residual tumor

Intraoperative high-field magnetic resonance imaging (iMRI) is used as an immediate intraoperative quality control, evaluating the extent of tumor removal during the surgical procedure and allowing us to extend resections in those cases where tumor remnants are documented. The aim of the study was to analyze the typical localization of residual tumor remnants, detected by iMRI during transsphenoidal surgery of pituitary adenomas. We reviewed a series of 72 patients. All patients presented with macroadenomas with or without suprasellar extension. After high-field MRI investigation, we divided the series preoperatively into totally resectable (TR) and non-totally resectable (NTR) tumors. Tumor remnants were documented by iMRI, obtained directly after tumor removal, as well as by intraoperative surgical inspection of the sellar content. In the TR group, we observed 23 cases suspicious for tumor remnants, located anteriorly, laterally, posteriorly, and suprasellar under descending folds of the diaphragm. Continuing surgery, upon a "second inspection", tumor resection could be completed in all cases. Incomplete removal of resectable pituitary adenomas could be avoided in a higher number of cases with the knowledge of the location of the typical remnant tumors. In those cases where it is not possible to achieve a complete resection of adenoma, further treatment can be planned at an earlier stage, without any need to wait for the conventional postoperative MRI scan performed 2 to 3 months after surgery.

Quantitative Measurement of Cerebral Oxygen Extraction Fraction Using MRI in Patients with MELAS

ObjectiveTo quantify the cerebral OEF at different phases of stroke-like episodes in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) by using MRI.MethodsWe recruited 32 patients with MELAS confirmed by gene analysis. Conventional MRI scanning, as well as functional MRI including arterial spin labeling and oxygen extraction fraction imaging, was undertaken to obtain the pathological and metabolic information of the brains at different stages of stroke-like episodes in patients. A total of 16 MRI examinations at the acute and subacute phase and 19 examinations at the interictal phase were performed. In addition, 24 healthy volunteers were recruited for control subjects. Six regions of interest were placed in the anterior, middle, and posterior parts of the bilateral hemispheres to measure the OEF of the brain or the lesions.ResultsOEF was reduced significantly in brains of patients at both the acute and subacute phase (0.266 ± 0.026) and at the interictal phase (0.295 ± 0.009), compared with normal controls (0.316 ± 0.025). In the brains at the acute and subacute phase of the episode, 13 ROIs were prescribed on the stroke-like lesions, which showed decreased OEF compared with the contralateral spared brain regions. Increased blood flow was revealed in the stroke-like lesions at the acute and subacute phase, which was confined to the lesions.ConclusionMRI can quantitatively show changes in OEF at different phases of stroke-like episodes. The utilization of oxygen in the brain seems to be reduced more severely after the onset of episodes in MELAS, especially for those brain tissues involved in the episodes.

Optimization of diagnosis indicator selection and inspection plan by 3.0T MRI in breast cancer

To optimize 3.0T MRI diagnosis indicator in breast cancer and to select the best MRI scan program. Totally 45 patients with breast cancers were collected, and another 35 patients with benign breast tumor served as the control group. All patients underwent 3.0T MRI, including T1- weighted imaging (T1WI), fat suppression of the T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), 1H magnetic resonance spectroscopy (1H-MRS) and dynamic contrast enhanced (DCE) sequence. With operation pathology results as the gold standard in the diagnosis of breast diseases, the pathological results of benign and malignant served as dependent variables, and the diagnostic indicators of MRI were taken as independent variables. We put all the indicators of MRI examination under Logistic regression analysis, established the Logistic model, and optimized the diagnosis indicators of MRI examination to further improve MRI scan of breast cancer. By Logistic regression analysis, some indicators were selected in the equation, including the edge feature of the tumor, the time-signal intensity curve (TIC) type and the apparent diffusion coefficient (ADC) value when b=500 s/mm2. The regression equation was Logit (P)=-21.936+20.478X6+3.267X7+ 21.488X3. Valuable indicators in the diagnosis of breast cancer are the edge feature of the tumor, the TIC type and the ADC value when b=500 s/mm2. Combining conventional MRI scan, DWI and dynamic enhanced MRI is a better examination program, while MRS is the complementary program when diagnosis is difficult.

1H magnetic resonance spectroscopy in the diagnosis of paediatric low grade brain tumours

IntroductionLow grade gliomas are the commonest brain tumours in children but present in a myriad of ways, each with its own treatment challenges. Conventional MRI scans play an important role in their management but have limited ability to identify likely clinical behaviour. The aim of this study is to investigate 1H magnetic resonance spectroscopy (MRS) as a method for detecting differences between the various low grade gliomas and related tumours in children. Patients and methodsShort echo time single voxel 1H MRS at 1.5 or 3.0T was performed prior to treatment on children with low grade brain tumours at two centres and five MR scanners, 69 cases had data which passed quality control. MRS data was processed using LCModel to give mean spectra and metabolite concentrations which were compared using T-tests, ANOVA, Receiver Operator Characteristic curves and logistic regression in SPSS. ResultsSignificant differences were found in concentrations of key metabolites between glioneuronal and glial tumours (T-test p<0.05) and between most of the individual histological subtypes of low grade gliomas. The discriminatory metabolites identified, such as choline and myoinositol, are known tumour biomarkers. In the set of pilocytic astrocytomas and unbiopsied optic pathway gliomas, significant differences (p<0.05, ANOVA) were found in metabolite profiles of tumours depending on location and patient neurofibromatosis type 1 status. Logistic regression analyses yielded equations which could be used to assess the probability of a tumour being of a specific type. ConclusionsMRS can detect subtle differences between low grade brain tumours in children and should form part of the clinical assessment of these tumours.

Early response evaluation for recurrent high grade gliomas treated with bevacizumab: a volumetric analysis using diffusion-weighted imaging

Bevacizumab is a novel treatment for the recurrent high-grade gliomas (rHGG). However, only a subset of the patients shows response to the bevacizumab treatment and the response evaluation using conventional criteria is difficult. The purpose of our study was to evaluate the early response for rHGG treated with bevacizumab using volumetric analysis of diffusion-weighted imaging (DWI). Twenty-nine patients who received bevacizumab therapy for rHGG were included in our study. All patients received a conventional MRI scan with DWI before and after the initial bevacizumab dose. For each MRI, we measured the total volume of the T2 hyperintense lesion (HT2) of the rHGG, the volume of foci with a lower ADC value than that of the normal cortex (LADC), and the proportion of LADC to HT2 (LADC/HT2). The Changes in the HT2, LADC and LADC/HT2 after bevacizumab treatment were also determined. Thereafter, those volumetric data were compared to the progression free survival (PFS). After the analyses, we found a significant negative correlation between the PFS and the LADC for the post-bevacizumab ADC maps (r = -0.413, P = 0.026). The patients with an LADC of <2.5 cm(3) showed a longer PFS than those with an LADC of ≥2.5 cm(3) (median = 135 vs. 91 days, P = 0.002) on the post-bevacizumab ADC maps. A multiple linear regression analysis revealed that only the post-bevacizumab LADC was a significant predictor of the PFS (P = 0.026). In conclusion, the post-bevacizumab LADC can be used for an early response evaluation and can predict the PFS for rHGG patients treated with bevacizumab.

Diffusion Tensor Magnetic Resonance Imaging in Patients with Multiple Sclerosis and its Relationship with Disability

Multiple sclerosis is a chronic inflammatory demyelinating disease of the central nervous system. Diffusion tensor magnetic resonance imaging (DTI) can yield important information on the in vivo pathological processes affecting water diffusion. The aim of this study was to quantitatively define water diffusion in normal-appearing white matter (NAWM) distant from the plaque, in the plaque, and around the plaque, and to investigate the correlation of these changes with clinical disability. Conventional MRI and DTI scans were conducted in 30 patients with MS and 15 healthy individuals. Fractional anisotropy maps and visible diffusion coefficients were created and integrated with T2-weighted images. Regions of interest (ROIs) were placed on the plaques on the same side, white matter around the plaques and NAWM on the opposite side. Only the white matter of healthy individuals in the control group, and FA and ADC values were obtained for comparison. The highest FA and lowest ADC were detected in the control group at the periventricular region, cerebellar peduncle and at all ROIs irrespective of location. There was a significant difference in comparison to the control group at all ROIs in patients with MS (p < 0.001 for all comparisons). No significant correlation between diffusion parameters and expanded disability state scale (EDSS) scores was found in patients with MS. DTI may provide more accurate information on the damage due to the illness, compared to T2A sequences, but this damage may not be correlated with the clinical disability measured by EDSS score.

의료영상을 이용한 인체장기의 분할 및 시각화

방사선과 의사들은 CT 및 MRI 스캐너로부터 얻어진 인체의 단면 영상을 연속적으로 보고 실제 3차원적으로 인체가 어떻게 구성되어 있는지를 상상하여 병변을 구별하는데, 의학영상을 이용한 인체 장기의 3차원 시각화는 2차원 형태의 인체 단면 영상들을 복잡한 알고리즘이나 고성능의 컴퓨팅 파워를 사용하여 실제 인체와 같이 3차원으로 재구성하여 보여준다. 단면 영상의 추적, 관심영역의 표시 및 추출등과 같은 2차원 영상분석은 시간이 많이 소모되고, 주관적일 수가 있으며, 수작업인 관계로 빈번한 에러가 발생하는 단점을 가지는데, 이와 같은 2차원 의료 영상 분석의 단점을 보완하기 위해 의학영상처리 기술과 접목한 3차원 의료 영상의 시각화는 필수적이라 할 수 있다. 명암값 임계치 방법, 영역확장(region growing) 방법, 윤곽선(contour) 추출 방법 및 변형모델(deformable model) 방법을 사용하여 인체의 각 장기를 분리하였으며, 텍스쳐분석(texture analysis)을 통하여 고안된 특징자를 이용하여 암 부분을 인식하는데 사용하였고, 원근투영(perspective projection) 및 볼륨 데이터의 표면을 렌더링하기 위해 마칭큐브(marching cube) 알고리즘을 사용하였다. 인체 및 분리된 장기에 대한 3차원 시각화는 방사선치료계획(radiation treatment planning), 외과 수술계획, 모의수술, 중재적(interventional)시술 및 영상유도수술(image guided surgery)에 효과적으로 사용될 수 있다. Conventional CT and MRI scans produce cross-section slices of body that are viewed sequentially by radiologists who must imagine or extrapolate from these views what the 3 dimensional anatomy should be. By using sophisticated algorithm and high performance computing, these cross-sections may be rendered as direct 3D representations of human anatomy. The 2D medical image analysis forced to use time-consuming, subjective, error-prone manual techniques, such as slice tracing and region painting, for extracting regions of interest. To overcome the drawbacks of 2D medical image analysis, combining with medical image processing, 3D visualization is essential for extracting anatomical structures and making measurements. We used the gray-level thresholding, region growing, contour following, deformable model to segment human organ and used the feature vectors from texture analysis to detect harmful cancer. We used the perspective projection and marching cube algorithm to render the surface from volumetric MR and CT image data. The 3D visualization of human anatomy and segmented human organ provides valuable benefits for radiation treatment planning, surgical planning, surgery simulation, image guided surgery and interventional imaging applications.

Microstructural tissue damage in normal appearing brain tissue accumulates with Framingham Stroke Risk Profile Score: Magnetization transfer imaging results of the Austrian Stroke Prevention Study

Background and purposeMagnetization transfer imaging detects cerebral microstructural tissue alterations. We examined the association between the Framingham Stroke Risk Profile (FSRP) score and magnetization transfer imaging (MTI) measures in pathological and normal appearing brain tissue in clinically normal elderly subjects to determine if stroke risk leads to brain tissue destruction beyond what is visible in conventional MRI scans. MethodsThe study cohort is from the Austrian Stroke Prevention Study (ASPS). A total of 316 subjects underwent MTI and had a complete risk factor assessment sufficient to calculate the FSRP score. There were 205 women and 111 men with a mean age of 70.2 years ranging from 54 to 82 years. Subjects were grouped into four categories of stroke risk probability ranging from 3% to 88% for men and 1% to 84% for women. ResultsA higher FSRP score was significantly and independently associated with a MTR peak position shift indicating global microstructural alterations in brain tissue (BT) and in normal appearing brain tissue (NABT). The mean MTR in white matter hyperintensities (WMH) correlated inversely with increasing stroke risk. Age explained most of the variance in MTR peak position, all other risk factors of the FSRP score contributed significantly but explained an additional 2% of the variance of this MRI measure, only. ConclusionIncreasing risk for stroke leads to microstructural brain changes invisible by standard MRI. The validity, the underlying pathogenic mechanisms and the clinical importance of these abnormalities needs to be further determined.

Perfusion and Diffusion Abnormalities of Multiple Sclerosis Lesions and Relevance of Classified Lesions to Disease Status.

ObjectiveHemodynamic abnormality and disruption of white matter (WM) integrity are significant components in the pathophysiology of multiple sclerosis (MS) lesions. However, the roles of stratified lesions with distinct degrees of hemodynamic and structural injury in disease states remain to be explored. We tested the hypothesis that hemodynamic and structural impairment, as assessed by cerebral blood volume (CBV) and fractional anisotropy (FA), respectively, characterizes the extent of tissue injury, and the load of lesion with substantial tissue destruction would reflect the disease status and therefore, would be related to clinical disability.MethodsSeven relapsing-remitting MS patients and seven healthy controls underwent perfusion, diffusion and conventional MRI scans. Based on T2-FLAIR and T1-weighted image, WM plaques were classified. After image coregistration, values of CBV and FA were estimated in three distinct lesion types (active, T1-hypointense and T1-isointense lesion) and compared with those obtained in WM from controls. A total of 1135 lesions were evaluated. Brain volumetric measurement and correlative analysis between brain atrophy, lesion volume and clinical disability were also performed.ResultsCompared with normal WM, significantly reduced CBV and FA were present in the T1-hypointense lesion, while insignificant changes in both parameters were exhibited in the T1-isointense lesion. However, increased CBV but significantly decreased FA was detected in the active lesion. A close spatial relationship between active and T1-hypointense lesion was observed. Lesion load represented by T1-hypointense plus active lesion volume significantly correlated with brain atrophy, which, in turn, significantly correlated with the severity of clinical disability.ConclusionA distinct combination of CBV and FA characterizes the status of a specific lesion type. A severe structural impairment does not solely occur in the T1-hypointense lesion, but is also associated with the active lesion. The burden of the lesion with extensive structural damage provides an image index, indicative of disease status.