Tesla MR Research Articles

Characterizing geometrical accuracy in clinically optimised 7T and 3T magnetic resonance images for high-precision radiation treatment of brain tumours.

Background and purposeIn neuro-oncology, high spatial accuracy is needed for clinically acceptable high-precision radiation treatment planning (RTP). In this study, the clinical applicability of anatomically optimised 7-Tesla (7T) MR images for reliable RTP is assessed with respect to standard clinical imaging modalities.Materials and methodsSystem- and phantom-related geometrical distortion (GD) were quantified on clinically-relevant MR sequences at 7T and 3T, and on CT images using a dedicated anthropomorphic head phantom incorporating a 3D grid-structure, creating 436 points-of-interest. Global GD was assessed by mean absolute deviation (MADGlobal). Local GD relative to the magnetic isocentre was assessed by MADLocal. Using 3D displacement vectors of individual points-of-interest, GD maps were created. For clinically acceptable radiotherapy, 7T images need to meet the criteria for accurate dose delivery (GD < 1 mm) and present comparable GD as tolerated in clinically standard 3T MR/CT-based RTP.ResultsMADGlobal in 7T and 3T images ranged from 0.3 to 2.2 mm and 0.2–0.8 mm, respectively. MADLocal increased with increasing distance from the isocentre, showed an anisotropic distribution, and was significantly larger in 7T MR sequences (MADLocal = 0.2–1.2 mm) than in 3T (MADLocal = 0.1–0.7 mm) (p < 0.05). Significant differences in GD were detected between 7T images (p < 0.001). However, maximum MADLocal remained ≤1 mm within 68.7 mm diameter spherical volume. No significant differences in GD were found between 7T and 3T protocols near the isocentre.ConclusionsSystem- and phantom-related GD remained ≤1 mm in central brain regions, suggesting that 7T MR images could be implemented in radiotherapy with clinically acceptable spatial accuracy and equally tolerated GD as in 3T MR/CT-based RTP. For peripheral regions, GD should be incorporated in safety margins for treatment uncertainties. Moreover, the effects of sequence-related factors on GD needs further investigation to obtain RTP-specific MR protocols.

Prediction of the sphenopalatine ganglion localization in computerized tomography images

Background: The sphenopalatine ganglion (SPG) is a target for several headache syndromes. Most of the groups targeting the SPG do not localize it directly, and this might account for some therapeutic failures. As the SPG cannot be seen on computerized tomography (CT) scans, magnetic resonance image (MRI) must be used to visualize the ganglion. It would be advantageous to be able to predict the location of the SPG on CT scans for those using fluoroscopy or CT-guided injections and for those in whom MRI is not accessible or contraindicated. Methods: We localized the SPG in 21 Caucasian patients (21 right and 17 left ganglia; total 38) in 3 tesla MR images subsequently fused with CT scans. We measured the distance from the SPG to two bony landmarks identified on CT scans. We then applied the average distances to find an estimated position of the SPG. The first landmark was the center of the anterior opening of the vidian canal (VC). The second landmark was a point on the sphenoidal bone, defined in an axial plane at the level of the center of the VC (S-point). The predicted position of the SPG measured from the VC and the sphenoidal bone were referred to as, respectively, vcSPG and sSPG. Finally, the distances between the SPG, as seen on MRI, and predicted vcSPG/sSPG were calculated. Results: The average distance between SPG as seen on the MRI images and the estimated position based on CT images were 1.82 mm (SD 0.83, range 0.22–3.57 mm) for vcSPG and 2.09 mm (SD 0.99, range 0.71–4.79 mm) for sSPG. Conclusions: The localization of the SPG can be predicted on CT images using bony landmarks. Localization of the SPG may be important in achieving successful therapeutic outcomes for treatments that are directed toward the SPG.

Assessment of diagnostic value of DWI technique in the evaluation of liver fibrosis

Introduction: The liver fibrosis is caused by extracellular accumulation of cluster, glycos amino glycans and proteoglycans, which this extracellular accumulation may limit the penetration and molecular movement of water in the tissue, so the Diffusion weighted imaging(DWI) technique is due to the sensitivity to the movement and release of water molecules Can show this restriction. Using this technique, in addition to examining the entire liver, sections of the liver tissue most affected by fibrosis can also be identified. The purpose of this study was to evaluate the use of apparent diffusion coefficient (ADC) measurement in DWI imaging technique and to investigate the correlation between this method and the method of sampling in patients. Materials and Methods: Twenty-five chronic viral hepatitis C patients were examined by 1.5 Tesla MR scanner with diffusion gradient encoding in three orthogonal directions at b-values of (200, 500, 700, and 1000 s/mm2). They were correlated to biopsy finding and graded according to Ishak scoring system. Hepatic ADC values were measured for patients. Results: The best correlation between ADC values and biopsy were seen at b-values 200, 700, and 1000 s/mm2. lesser correlation was obtained at b-values of 500 s/mm2. Cut off values between different grades of fibrosis were calculated and presented in the text. Conclusion: ADC measured with DWI is a reliable non-invasive technique for quantification of liver fibrosis, and could replace liver biopsy in certain cases.

A machine learning approach for distinguishing uterine sarcoma from leiomyomas based on perfusion weighted MRI parameters

PurposeTo propose a computer-assisted method for distinguishing uterine sarcoma from leiomyomas based on perfusion weighted magnetic resonance imaging (PWI). Materials and methodsForty-two women confirmed to have a total of 60 masses (10 uterine sarcomas and 50 benign leiomyomas) were included. The reference diagnosis was based on postoperative histopathological examination. All women underwent the standard MRI protocol with 3-Tesla MR imager (Magnetom Trio, Siemens, Erlangen, Germany) for assessment of myometrial masses, followed by PWI. For each mass, two regions of interest (ROI) were outlined manually by an experienced radiologist; one (ROIL) represented the entire tumor while the other (ROIs) was placed on the area of the lesion with the most marked contrast enhancement. Two additional ROIs with diameters similar to ROIs (3.0 to 3.1 mm) were placed on psoas muscle (ROIP) and myometrium (ROIM) in order to provide baselines for comparisons. The obtained ROIs of PWI images were then analyzed using the DCE Tool plug-in (version 2.0SP1) within ClearCanvas (Toronto, Ontario, Canada) framework. The DCE Tool provides seven parameters (Ktrans, kep, Vb, IAUC, initial slope, peak, the mean squared error) for modelling contrast uptake within an ROI using the modified Tofts model. Parameters extracted from the ROIs were fed into a decision tree ensemble, which classified the corresponding lesions either as malignant or benign. The leave-one-out cross validation (LOOCV) was utilized to evaluate the performance of the classifier. ResultsNone of the parameters extracted from ROIL or ROIs differed significantly between uterine sarcoma and benign leiomyomas (all p > 0.05). The overall accuracy of 66.7% was obtained by feeding seven parameters extracted from ROIL to the classifier. When 21 features extracted from ROIL, ROIM, and ROIP were fed into the classifier an accuracy of 91.7%, sensitivity of 100%, and specificity of 90% were achieved in the optimal operating point of classifier. ConclusionAlthough none of the PWI parameters differed significantly between benign and malignant lesions, when the information provided by the extracted features was aggregated using a machine learning method, a promising discriminative power was obtained. This suggests that the proposed model for combining the PWI parameters is potentially useful for differentiating uterine sarcoma from leiomyomas.

Assessment of metallic patient support devices and other items at 7-Tesla: Findings applied to 46 additional devices

ObjectiveRecently, the first 7-Tesla MR system was approved for clinical use in Europe and the United States. Unfortunately, few metallic objects have undergone testing in association with this high-field-strength scanner, including essential equipment such as patient support devices and other items. Therefore, the objective of this investigation was to assess metallic patient support devices and other items for translational attraction at 7-Tesla. MethodsThirteen different metallic items (e.g., gurney, Mayo stand, step stool, utility table, wheelchair, etc.) underwent testing for translational attraction using a previously described methodology in association with a clinical 7-T MR system. The findings were categorized as pass (no translational attraction) or fail (the item was attracted by the scanner). ResultsEvery metallic item tested exhibited a lack of magnetism while in a worst-case use position and, thus, passed the test for translational attraction in associated with the 7-Tesla MR system. ConclusionsThe different thirteen different metallic patient support devices and other items can be designated as MR Conditional at 7-T or less. Furthermore, because each item represented a worst-case with respect to its mass and the type of metallic material used for its fabrication, the results can be applied to 46 additional smaller items made from the same material or material with a lower magnetic susceptibility. This expanded list of essential patient support devices and other items will facilitate the clinical use of a comparable 7-Tesla scanner, or another UHF scanner with similar fringe field characteristics.

Contrast-Enhanced Magnetic Resonance Angiography Using a Novel Elastin-Specific Molecular Probe in an Experimental Animal Model.

Objectives The aim of this study was to test the potential of a new elastin-specific molecular agent for the performance of contrast-enhanced first-pass and 3D magnetic resonance angiography (MRA), compared to a clinically used extravascular contrast agent (gadobutrol) and based on clinical MR sequences. Materials and Methods Eight C57BL/6J mice (BL6, male, aged 10 weeks) underwent a contrast-enhanced first-pass and 3D MR angiography (MRA) of the aorta and its main branches. All examinations were on a clinical 3 Tesla MR system (Siemens Healthcare, Erlangen, Germany). The clinical dose of 0.1 mmol/kg was administered in both probes. First, a time-resolved MRA (TWIST) was acquired during the first-pass to assess the arrival and washout of the contrast agent bolus. Subsequently, a high-resolution 3D MRA sequence (3D T1 FLASH) was acquired. Signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) were calculated for all sequences. Results The elastin-specific MR probe and the extravascular imaging agent (gadobutrol) enable high-quality MR angiograms in all animals. During the first-pass, the probes demonstrated a comparable peak enhancement (300.6 ± 32.9 vs. 288.5 ± 33.1, p > 0.05). Following the bolus phase, both agents showed a comparable intravascular enhancement (SNR: 106.7 ± 11 vs. 102.3 ± 5.3; CNR 64.5 ± 7.4 vs. 61.1 ± 7.2, p > 0.05). Both agents resulted in a high image quality with no statistical difference (p > 0.05). Conclusion The novel elastin-specific molecular probe enables the performance of first-pass and late 3D MR angiography with an intravascular contrast enhancement and image quality comparable to a clinically used extravascular contrast agent.

Static magnetic field exposure in 1.5 and 3Tesla MR scanners does not influence pain and touch perception in healthy volunteers.

Magnetic field therapy is a popular approach to pain therapy, but scientific evidence on treatment effects or even effects on sensory and pain perception in healthy controls is scarce. In the present randomized, placebo-controlled study, we investigated the influence of static magnetic field exposure on sensory (touch) and pain (pinprick, pressure and heat) perception. Eighteen healthy volunteers (age: 23±2years, nine women) underwent three 10-min static magnetic field exposures using field strengths of 0T (placebo), 1.5T and 3T within clinical MR scanners in randomized order on three separate days. Participants were blinded to magnetic field strength. Experimental sensory and pain testing was performed immediately before and after each magnetic field exposure. There was no significant effect of field strength on the assessed experimental sensory and pain testing parameters (mechanical detection threshold, pinprick threshold, pressure pain threshold, heat pain threshold and suprathreshold heat pain rating). We found no evidence that a 10-min 1.5T or 3T static magnetic field exposure affects experimental sensory or pain perception in young healthy volunteers. We used clinical MR scanners to investigate the effect of magnetic fields on pain perception. Using a rigorous, straightforward, placebo-controlled design, no effect of static magnetic fields on human experimental pain perception was detected. This provides a base for a more systematic investigation of magnetic field effects on pain.

Assessment of Myocardial Perfusion at Rest and During Stress Using Dynamic First-Pass Contrast-Enhanced Magnetic Resonance Imaging in Healthy Dogs.

Objective: To assess the feasibility of myocardial perfusion analysis in healthy dogs using dynamic contrast-enhanced cardiac magnetic resonance (DCE-MR) imaging at rest and during simulated stress with two doses of adenosine.Animals: Ten healthy beagle dogs.Procedures: Dogs were anesthetized and positioned in dorsal recumbency in a 3.0 Tesla MR scanner. Electrocardiogram-triggered dynamic T1-weighted ultrafast gradient echo images of three slices in short-axis orientation of the heart were acquired during breath holds and the first pass of gadolinium contrast. Image acquisition was performed after 4 min infusion of 140 μg/kg/min and 280 μg/kg/min adenosine and, after a washout period, without adenosine, respectively. Images were processed by dividing each slice into 6 radial segments and perfusion analysis was performed from signal intensity-time data.Results: No differences in perfusion parameters were found between segments within any of the slices, but significant differences were found between slices for peak enhancement, accumulated enhancement, and the maximum upslope. In addition, significant differences were found within each slice between data at rest and during adenosine-induced stress for the relative and absolute maximum upslope, relative peak enhancement, time to peak, and accumulated enhancement although inter-individual variation was large and no difference was found between the two stress tests for some parameters.Conclusion and Clinical Relevance: Results of this study showed that rest and stress myocardial perfusion can be assessed using DCE-CMR in dogs using the methods described. Both, adenosine dose and slice appear to affect perfusion parameters in healthy dogs and individual response to adenosine was variable.

Characterization of prostate cancer with MR spectroscopic imaging and diffusion-weighted imaging at 3 Tesla

PurposeTo retrospectively measure metabolic ratios and apparent diffusion coefficient (ADC) values from 3-Tesla MR spectroscopic imaging (MRSI) and diffusion-weighted imaging (DWI) in benign and malignant peripheral zone (PZ) prostate tissue, assess the parameters' associations with malignancy, and develop and test rules for classifying benign and malignant PZ tissue using whole-mount step-section pathology as the reference standard. MethodsThis HIPAA-compliant, IRB-approved study included 67 men (median age, 61 years; range, 41–74 years) with biopsy-proven prostate cancer who underwent preoperative 3 T endorectal multiparametric MRI and had ≥1 PZ lesion >0.1 cm3 at whole-mount histopathology. In benign and malignant PZ regions identified from pathology, voxel-based choline/citrate, polyamines/choline, polyamines/creatine, and (choline + polyamines + creatine)/citrate ratios were averaged, as were ADC values. Patients were randomly split into training and test sets; rules for separating benign from malignant regions were generated with classification and regression tree (CART) analysis and assessed on the test set for sensitivity and specificity. Odds ratios (OR) were evaluated using generalized estimating equations. ResultsCART analysis of all parameters identified only ADC and (choline + polyamines + creatine)/citrate as significant predictors of cancer. Sensitivity and specificity, respectively, were 0.81 and 0.82 with MRSI-derived, 0.98 and 0.51 with DWI-derived, and 0.79 and 0.90 with MRSI + DWI-derived classification rules. Areas under the curves (AUC) in the test set were 0.93 (0.87–0.97) with ADC, 0.82 (0.72–0.91) with MRSI, and 0.96 (0.92–0.99) with MRSI + ADC. ConclusionWe developed statistically-based rules for identifying PZ cancer using 3-Tesla MRSI, DWI, and MRSI + DWI and demonstrated the potential value of MRSI + DWI.

무릎활액막비대의 이중반전기법에서 반전시간 연구 - 3.0 Tesla 자기공명영상 시스템에서 T2-강조영상과 PD-강조영상의 비교 -

본 연구의 목적은 이중반전기법을 이용하여 무릎활액막비대 진단에 도움을 주는 것이다. 3.0T 자기공명영상 시스템에서 반전회복 값을 TI1/TI2(2805/229 msec)로 설정하여 이중반전기법에 적용하였다. 이때 조영제는 사용하지 않았다. 윤활막과 삼출액의 SNR, CNR 값에서 이중반전기법이 T2-강조영상, PD-강조영상 보다 높은 결과를 얻을 수 있었다. 결론적으로 본 연구에서 제안하는 반전회복 값을 이용한 이중반전기법은 기존의 영상에 비해 무릎활액막비대 진단에 유용함을 알 수 있었다. 향후 다양한 질환에 이중반전기법을 적용하는 연구에서 본 연구가 기초 자료를 제공할 것이라 사료된다.

P044] Imaging biomarker analysis of structural MR images for glioma grading

Purpose Preoperative differentiation between low and high grade gliomas is critical for adapting appropriate treatment strategies. However biopsy based diagnosis presents limitations in assessing tumor diffusive and solid growth patterns, respectively, due to the potential subsampling of tumor region as well as the associated patient risk. The purpose of this study is to investigate the value of imaging biomarker analysis in terms of a 3D texture analysis of T1 pre/post-contrast, T2, and DTI maps in the evaluation of tumor heterogeneity towards glioma grading. Methods In this study a semi-automated segmentation technique, based on T1 pre/post-contrast, T2, and DTI parametric maps, is used for the identification of the tumor core and peritumoral edema regions from 3 Tesla MR Data. 3D Texture analysis was performed on 10 low grade and 10 high grade glioma patients, considering several 3D Histogram, Gray Level Co-Occurrence Matrices (GLCM) and Gray Level Run Length Matrices (GLRLM) derived features. Results Initial evaluation of the proposed method is performed in terms of textural features statistical significant differences between the two tumor groups, with the prospect of implementing an advance classification scheme for identifying more complex correlations. The preliminary results suggest that 3D Texture Analysis findings might be utilized as a surrogate biomarker for the global non-invasive assessment of glioma grading. Conclusions Results demonstrate the potential role of Texture Analysis of 3D tumor imaging appearance in structural MRI, for pre-treatment gliomas grade differentiation.

(OA43) Delineation of a Cardiac PRV Using Real-Time Magnetic Resonance Imaging for Cardiac Protection in Thoracic and Breast Radiation Therapy

Historically, increased cardiac radiation dose has been associated with late cardiotoxicity events in patients with thoracic and breast malignancies. Recently, a prospective trial also revealed correlation between cardiac dose and early toxicity, including reduced overall survival in patients receiving curative-intent treatment. While breath-hold techniques reduce motion, they cannot account for cardiac cycle motion. We conducted a prospective cine magnetic resonance imaging (cMRI) study and applied an established scale-invariant feature transform (SIFT)-based algorithm to track and evaluate heart motion. We hypothesized that cMRI could be used to define a cardiac planning organ-at-risk volume (PRV) for routine application in radiation planning to improve cardiac protection. Imaging was performed on a 1.5 Tesla MR scanner (Philips Ingenia 1.5T MR System). 16 acquisitions were obtained per subject using a balanced-steady-state gradient echo sequence. Single-plane cMRI was performed in four sequential sagittal and four sequential coronal planes, spanning the heart in equidistant left-right (LR) and anterior-posterior (AP) intervals. Free-breathing (FB) and deep-inspiratory-breath-hold (DIBH) acquisitions were performed at each plane. In-plane cardiac motion was assessed on all image sets for each subject. The reference image and each image within the corresponding acquisition image set were registered via a previously published technique that describes pixels by high-dimensional descriptors, incorporating nearby intensity gradients rather than pixel intensity alone. Each descriptor, defined by the scale-invariant feature transform (SIFT) algorithm, is a set of histograms of intensity gradients within sub-regions surrounding a given pixel. Pixel trajectories were then identified by minimizing an objective function to locate best-matching descriptors between the reference image and each image within an acquisition. Subject-specific pixel motion ranges were derived by averaging slice-by-slice motion of each pixel to yield mean values for AP, LR, and superior-inferior (SI) directions. For each subject, average maximum range of pixel displacement and average pixel-based interquartile range (IQR) of displacement were calculated. These values were then utilized and averaged across the cohort to calculate planning organ-at-risk volume (PRV) expansions at FB and DIBH. 20 subjects were enrolled with median age 34.5 years (range 20-78), BMI 23.75 (range 17.7-33.3), and height 64 inches (range 57-69). A total of 3,120 image frames were collected per patient in coronal and sagittal planes, at DIBH and FB, with 62,400 frames analyzed across the cohort. SIFT methodology was successfully implemented in all patients to track motion. The cohort average of maximum motion ranges comprised PRV margin expansions of 13.7±1.8mm SI, 6.9±1.4mm AP, and 7.7±1.2mm LR plane at FB; expansions for DIBH were 7.1±1.5mm SI, 5.1±1.4mm AP, and 5.6±1.3mm LR. IQR-based PRVs, calculated to encompass the most frequent range of cardiac displacement, comprised 3.7±0.7mm SI, 1.2±0.4mm AP, and 1.4±0.3mm LR at FB and 1.8±0.6mm SI, 1.0±0.3mm AP, and 1.3±0.4mm LR at DIBH. IQR-based PRV expansions were then successfully applied for both locally-advanced lung cancer and breast cancer treatment planning. We successfully utilized SIFT-based motion-tracking for analysis of 62,400 prospectively gathered cine MR image frames to identify and apply a cardiac PRV for treatment planning to improve cardiac protection in breast and thoracic radiation.

EP-2178: Use of the PTW Starcheck Maxi MR for commissioning a 1.5 Tesla MR Lina

EP-2178: Use of the PTW Starcheck Maxi MR for commissioning a 1.5 Tesla MR Lina

P.3.010 - Imbalance in the deployment of neural resources during visual working memory encoding in schizophrenia as a possible intermediate phenotype

Visual working memory (VWM) deficits are a prominent impairment in patients with schizophrenia (SCZ) and are associated with an inefficient encoding process [1] and with neuronal dysfunctions [2]. Both behavioural and neurofunctional impairments can be observed in unaffected first-degree relatives of patients (REL) as well and are thus discussed as a possible intermediate phenotype of the disorder [3,4]. In this study we investigated the characteristics of WM encoding and its neural substrates in SCZ and REL to evaluate their potential role as an intermediate phenotype of the disorder. We examined n = 25 SCZ, n = 22 REL and n = 25 healthy control subjects (CON). All subjects underwent whole brain fMRI scans in a 3 Tesla MR system. During the fMRI scan, a VWM change-detection task was presented, which showed a sample array consisting of 3 red lines of different orientation that should be memorized. After a delay interval of either 100ms, 400ms or 800ms (SOA = stimulus onset asynchrony) a pattern mask was shown, followed by another delay period and a test array. The longer the delay interval until masking, the more durable the VWM representations were expected to be. Response accuracy served as an estimate of the grade of VWM encoding. The behavioural data was analyzed using a two-way univariate ANOVA with repeated measures and post hoc tests. For group statistics of the event-related fMRI data we conducted a random-effects GLM (RFX-GLM) and a subsequent ANOVA with 'group' as a between-subjects factor (3 levels) and 'SOA' as within-subjects factor (3 levels). For behavioural performance in the VWM task we found significant main effects of 'group' (p = 0.026) and 'SOA' (p = 0.013). The longer the SOA interval, the greater the response accuracy across groups (significant linear trend; p = 0.009). Response accuracy was significantly lower in SCZ compared to CON (p = 0.011) and REL (p = 0.041). We observed aberrant neural activation during VWM encoding for both SCZ and REL compared to CON: across SOA conditions SCZ showed widespread neural deactivation, including the DLPFC and precentral gyrus, as well as increased activity of the anterior cingulate. In REL, we observed a shift in neural activation in regard to the length of the SOA interval: at SOA 100 REL showed only decreased activity in the superior frontal gyrus and fusiform gyrus; at SOA 400 we observed decreased activity in the middle frontal gyrus and increased activity in the superior frontal gyrus; and at SOA 800 REL showed only increased activity in the inferior frontal gyrus. The findings indicate that impaired VWM in SCZ may emerge from an insufficient engagement of the functional WM network with concomitant anterior cingulate hyperactivity during encoding. In REL, the shift from decreased to increased activity might reflect a compensatory process: hypoactivity might point towards fundamental neural dysfunctions—at lighter processing demands local hyperactivity might ensure accurate VWM performance. Neural dysfunctions during VWM encoding should thus be considered as a candidate intermediate phenotype of SCZ.

Liver function correlates with liver-to-portal vein contrast ratio during the hepatobiliary phase with Gd-EOB-DTPA-enhanced MR at 3 Tesla.

To determine if liver-to-portal vein contrast ratio (LPC) correlates with liver function in patients with hepatitis B virus (HBV)-related cirrhosis on gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced MR imaging. A total of 92 patients with normal (n=20) or HBV-related cirrhotic livers graded by Child-Pugh class A (n=50), B (n=17) or C (n=5) who underwent Gd-EOB-DTPA-enhanced 3Tesla MR imaging were retrospectively reviewed. LPC was defined as the signal intensity ratio of liver parenchyma to portal vein on hepatobiliary phase (HBP) acquired at 20min, and it was compared between normal and cirrhotic livers. The correlation between LPC and hepatic function parameters at HBP after injection was quantitatively analyzed as well. LPC differed between normal and cirrhotic livers significantly (P<0.001). LPC constantly and significantly decreased from normal to cirrhotic livers with Child-Pugh class C at HBP imaging (P<0.001). Multiple regression analysis revealed that total bilirubin (P=0.011), albumin (P<0.001), and platelet count (P=0.007) were independent predictors of LPC at HBP imaging. A receiver operating characteristic (ROC) curve analysis revealed that the optimal cutoff value for LPC to distinguish normal group from cirrhotic groups was 2.05 (AUC 0.98) with a sensitivity of 84.1% and a specificity of 100%. The level of LPC on Gd-EOB-DTPA MR imaging can efficaciously indicate the severity of liver function in patients with HBV-related cirrhosis and was correlated with liver function parameters significantly. It might be used as an alternative imaging biomarker for assessing liver function.

ViP-CSI: Virtual Phantom Chemical Shift Imaging

To apply the Virtual Phantom (ViP) method for generating reference signals, to the chemical shift imaging (CSI) technique. The ViP method, previously used for generating reference images in magnetic resonance imaging (MRI), was here extended to generate reference peaks in the MR spectra acquired with a 2D-CSI sequence. Theoretical analysis was carried out to design the ViP signal. ViP-2D-CSI experiments were performed on a 4.7 Tesla MR scanner. Data analysis was carried out with the jMRUI software to fit the ViP peaks to determine their amplitude and frequency. Based on the theoretical analysis, it was found that the ViP peak could be generated by transmitting the ViP signal only in one repetition time of the 2D-CSI sequence. The amplitude and frequency of the ViP peak could be precisely adjusted and fine-tuned. The ViP peak was uniform over all CSI voxels, both in amplitude and in frequency. Furthermore, a good stability of the ViP reference amplitude and frequency was observed. The ViP method provides a means to generate a reference MR peak in 2D-CSI experiments. This could be of interest for signal quantification in CSI experiments.

Comparison of Brain Atrophy, Cognition and Optical Coherence Tomography Results Between Multiple Sclerosis Patients and Healthy Controls.

Cognitive impairment is also an important cause of disability in MS in addition to motor, sensory, visual, and cerebellar affections. The aim of this study is to show the relation between the cognitive disability in MS with brain atrophy and retinal nerve fiber layer (RNFL). Forty-three multiple sclerosis (MS) patients, and 15 healthy individuals as controls were included in the study. MS patients were divided into three groups as relapsing-remitting MS (RRMS), relapsing-remitting with optic neuritis (RRMS+ON), and secondary-progressive MS (SPMS). An experienced psychologist performed modified Wechsler Memory Scale Revised form (WMS-R), Lines Orientation test, Stroop Color Word Interference test (STROOP), Standard Raven Progressive Matrices (SRPM), Benton Facial Recognition Test, verbal fluency test, and Paced Auditory Serial Addition tests in all cases. Optic coherence tomographies (OCT) were done. Cranial subcortical volumes of all subjects were measured using 3-dimensonal T1A imagines obtained by the cranial subcortical 1.5 tesla MR device (fully automatic Freesurfer program). Brain parenchymal fractions were calculated by proportioning the obtained volume measurements to the total intracranial volume. Fifty-eight subjects (65.5% female, 34.5% male) were enrolled in the study. There were significant differences among the groups in terms of parenchymal thickness, volumes of third ventricle, and white matter. There was a significant correlation between the volumes of the deep gray matter, mesial temporal structures and lateral ventricular volumes, and the test results of the WMS-R. OCT scores of all MS patients, whether or not they experienced optic neuritis, had increased, being worse especially in the SPMS group. Correlation between RNFL and the brain parenchymal fractions of the patients were statistically significant. Manual methods instead of automatic segmentation method are being more commonly used in the studies with brain atrophy and MS in our country. A significant correlation between OCT scores and brain atrophy is shown with our present study, and this is followed as a reflection of decrease in cognitive tests that provides valuable and reliable knowledge for the literature.

Measurement of the permeability, perfusion, and histogram characteristics in relapsing-remitting multiple sclerosis using dynamic contrast-enhanced MRI with extended Tofts linear model.

To investigate the application value of using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with extended Tofts linear model for relapsing-remitting multiple sclerosis (RRMS) and its correlation with expanded disability status scale (EDSS) scores and disease duration. Thirty patients with multiple sclerosis (MS) underwent conventional magnetic resonance imaging (MRI) and DCE-MRI with a 3.0 Tesla MR scanner. An extended Tofts linear model was used to quantitatively measure MR imaging biomarkers. The histogram parameters and correlation among imaging biomarkers, EDSS scores, and disease duration were also analyzed. The MR imaging biomarkers volume transfer constant (Ktrans), volume of the extravascular extracellular space per unit volume of tissue (Ve), fractional plasma volume (Vp), cerebral blood flow (CBF), and cerebral blood volume (CBV) of contrast-enhancing (CE) lesions were significantly higher (P < 0.05) than those of nonenhancing (NE) lesions and normal-appearing white matter (NAWM) regions. The skewness of Ve value in CE lesions was more close to normal distribution. There was no significant correlation among the biomarkers with the EDSS scores and disease duration (P > 0.05). Our study demonstrates that the DCE-MRI with the extended Tofts linear model can measure the permeability and perfusion characteristic in MS lesions and in NAWM regions. The Ktrans, Ve, Vp, CBF, and CBV of CE lesions were significantly higher than that of NE lesions. The skewness of Ve value in CE lesions was more close to normal distribution, indicating that the histogram can be helpful to distinguish the pathology of MS lesions.

Role of MRI in Characterization of Benign Hepatic Focal Lesions

Background: nowadays, magnetic resonance plays a key role in management of liver lesions, using a radiation-free technique and a safe contrast agent profile. The heightened soft-tissue resolution and sensitivity to intravenous contrast agents provided by magnetic resonance imaging (MRI) makes it an invaluable problem-solving tool for fully characterizing focal liver lesions (FLL). Diffusion-weighted imaging (DWI) sequences have been shown to be an emerging contributor for liver MRI and are being incorporated in most abdominal MR protocols. Aims: To determine the role of MRI in characterization of benign hepatic focal lesions. Patients and methods: This study included 30 patients (11 M, 19 F with mean age of 47.7 years) with benign hepatic focal lesions. They were simple cyst (n =6), hemangioma (n = 11), abscess (n = 4), adenoma (n = 2), focal nodular hyperplasia (n = 3), Hydatid cyst (n=1) and regenerative nodules (n = 3). They underwent routine MR imaging and diffusion MR weighted imaging using 1.5 tesla MR unit (Philips Achieva). Diffusion MR imaging was done using spin echo type of single shot echo planar imaging (EPI) with b value of 0, &800 mm2/sec. The apparent diffusion coefficient (ADC) map was reconstructed and ADC value was measured. The mean ADC values correlated with histopathological results as well as followup imaging results. Results: The mean ADC values were significantly different within benign hepatic focal lesions (P < 0.001). There was highly statically significant relation between cyst and hemangioma (p-value < 0.001), cyst and abscess (p-value <0.001), hemngioma and abscess (p-value < 0.001), while there was no statically significance relation between adenoma and focal nodular hyperplasia (p-value < 0.74), adenoma and regenerative nodules (p-value < 0.67) and focal nodular hyperplasia and regenerative nodules (p-value < 0.41). Conclusions: benign liver lesions are frequently encountered in clinical practice and their characterization may be sometimes difficult. The problem of lesion characterization is mainly crucial and may influence therapeutic decisions and patient’s management. The role of imaging is therefore a mainstay and MRI, with its multi parametric potentialities, is a highly accurate method for lesion detection and characterization. Nevertheless, benign lesions may be sometimes “non-typic” in their cellular content and vascular behavior and lesions biopsy can be necessary for definitive characterization.

Magnetic Susceptibility Artifacts by Air Space in Lumbar MRI Sagittal Fat Suppression

The purpose of this study was to investigate whether the air space formed by the normal anatomical lordosis of the lumbar spine and the table affects magnetic susceptibility artifacts in sagittal MRI images using fat suppression. Thirteen patients complaining of simple low back pain were examined using a 3.0 Tesla MR system and 12-channels dS posterior coil. T2 fat-suppressed sagittal images were examined when the knee was extended and when it was supported by a 50° tilt support. The mean standard deviation of the images when the knee support was used was 131.00 ± 19.31, and it was 220.58 ± 26.86 when the knee was extended. In conclusion, it was confirmed that the air space formed between the table and the anatomical structures due to the curvature of the lumbar spine led to uniform images because of the magnetic susceptibility artifacts.