Region Of Interest Values Research Articles

Evaluation of trabecular pattern of mandible using fractal dimension, bone area fraction, and gray scale value: comparison of cone-beam computed tomography and panoramic radiography.

This study was performed to compare the fractal dimension (FD), bone area fraction (BAF), and gray scale value (GSV) on digital panoramic radiography (DPR) and cross-sectional cone-beam computed tomography (CBCT) using image analysis and to determine whether a relationship exists among parameters associated with bone quality. Thirty edentulous human hemimandibles were scanned by DPR and CBCT. Ninety regions of interest (ROIs) were evaluated on DPR and CBCT images to calculate the FD and BAF. The GSV of the ROI on CBCT was also calculated. Statistically significant differences were observed in the FD values of the ROIs between DPR and CBCT (p = 0.002) and in the BAF values of ROIs between DPR and CBCT (p = 0.017). The Spearman's correlation test revealed a statistically significant high correlation between the FD and BAF values of the ROIs on DPR and between the FD and BAF values of the ROIs on CBCT (p < 0.01). No significant correlations were observed between the GSVs of ROIs on CBCT and the FD values of ROIs on DPR, the BAF values of ROIs on DPR, the FD values of ROIs on CBCT, and the BAF values of ROIs on CBCT (p > 0.05). The GSV did not support the FD and BAF. Additionally, DPR and CBCT did not have similar image quality for assessing the FD, BAF, and GSV. In evaluating the trabecular structure, the use of panoramic radiographs should be continued because the image resolution of CBCT is lower and its generalized dose is higher than that of panoramic radiography. These results may serve as a reference for clinical practitioners using dental CBCT to analyze the trabecular structures of alveolar bones.

Diffusion-weighted magnetic resonance imaging of thorax in diagnosis of pulmonary embolism

Pulmonary embolism (PE) has a high mortality rate and a considerable incidence in emergency care. Thorax computed tomography (CT) angiography is the primary diagnosis method for PE, but has many contraindications. In the present study, we aimed to determine the usability of Diffusion-weighted magnetic resonance imaging (DWMRI) in diagnosis of pulmonary embolism. Patients, diagnosed as pulmonary embolism previously by thorax CT angiography, were taken DWMRI. Demographic parameters, complaints, laboratory values and imaging findings were recorded on standart forms. Twenty nine patients, who were diagnosed as pulmonary emboli, were evaluated. Many of them were female(69%) and the mean of age was 61 years. Dyspnea and chest pain were the main complaints. Atelectasis(69,1%) and pulmonary infarct(30,9%) were determined lesions on CT and DWMRI. Region of interest (ROI) were determined by using MRI (T2) images. Three different ROI values were placed on areas and apparent diffusion coefficient (ADC) values were calculated for peripheric lung lesions. Significant difference was determine between mean ADC values of atelectasis and pulmonary infarct lesions (p

Preliminary Diagnostic Accuracy of Multiparametric Magnetic Resonance Imaging to Detect Residual Prostate Cancer Following Focal Therapy with Irreversible Electroporation

BackgroundIt is recommended to perform multiparametric magnetic resonance imaging (mpMRI) in the follow-up following focal therapy of prostate cancer (PCa). ObjectiveTo determine the diagnostic accuracy of mpMRI to detect residual PCa following focal therapy with irreversible electroporation. Design, setting, and participantsSeventy-six patients with biopsy-proven localized PCa consented for primary irreversible electroporation between February 2013 and March 2016. Final analysis was performed on 50 patients that received follow-up mpMRI at 6 mo, serial prostate-specific antigen (PSA) testing, and transperineal template-mapping biopsies at 12 mo. Outcome measurements and statistical analysisOutfield regions of interest (ROI) were reported using PI-RADS version 2. A binary outcome (suspicious vs nonsuspicious) was given for the infield ablation zone. Sensitivity, specificity, positive predictive values, and negative predictive values were calculated for different definitions of significant PCa: (1) Gleason ≥4+3 or Gleason ≥3+3 with a maximum cancer core length ≥6mm, (2) Gleason ≥3+4 or Gleason ≥3+3 with a maximum cancer core length ≥4mm, for outfield and infield ROI. Multivariate linear regression analyses evaluated the additional value of nadir PSA. Results and limitationsSensitivity, specificity, positive predictive values, and negative predictive values of infield ROI was 43%, 86%, 33%, and 90% for definition 1 and 38%, 86%, 33%, and 88% for definition 2, respectively. For outfield ROI this was 33%, 82%, 20%, and 90% for definition 1 and 38%, 86%, 50%, and 80% for definition 2. PSA had no additional value in predicting residual significant PCa. Limitations include retrospective design, single reader, and low incidence of residual PCa. ConclusionsOur preliminary data suggest that mpMRI can rule out high-volume residual PCa. However, follow-up biopsies should still be performed to determine oncological control. Patient summaryMultiparametric magnetic resonance imaging is able to detect high-volume significant prostate cancer following focal therapy. Prostate biopsies are still required in the follow-up of focal therapy as (low-volume) significant prostate cancer is being missed by multiparametric magnetic resonance imaging.

Ex vivo magnetic resonance imaging using hyaluronic acid fillers: Differences between monophasic and biphasic fillers.

Hyaluronic acid (HA) is an anionic, non-sulfated glycosaminoglycan distributed throughout the human skin and injectable HA fillers are the most commonly used in aesthetic field. This study aimed to determine if differences in physical characteristics of HA products (monophasic or biphasic fillers) affect the patterns of magnetic resonance imaging (MRI). Twenty biphasic fillers and nine monophasic fillers were obtained from a commercial source, and examined with a 3.0Tesla MRI scanner. Visual assessments and measurements of signal intensity for region of interest (ROI) were performed. A non-parametric Wilcoxon rank sum test was used to compare the ROI values. Visual assessments by a radiologist did not show significant differences between the two types of fillers. While the signal intensity between the two types of filler did not differ significantly for T1-weighted images, the signal intensity of the biphasic filler was lower than that of the monophasic filler for T2-weighted images (P<.01). Monophasic and biphasic HA fillers exhibited different MRI properties. Our findings may provide better insights into the use of in vivo MRI to evaluate aesthetic, procedure-related complications.

3D Dosimetry based on a new optical approach for dosimetry gels: Use of the polarisation ratio of the scattering light

Several investigations have been carried out by researchers over past two decades to evaluate and perform the reading of gel dosimeters for the three-dimensional measurement of radiation fields. Imaging of the gels has been successfully accomplished with clinical MRI and via laser-based optical scanning using transmission of the light. We report here the methodology and results of a preliminary study carried out to evaluate the utility of a new and simplified approach to make 3D imaging of gel radiation dosimeters based on the scattering light analysis. For the purpose of this initial investigation, nMAG gel has been studied by our method. All pictures were evaluated through a region-of-interest (ROI) analysis to obtain the average change in image density in each sample as a function of the radiation dose. These measured ROI values were subjected to any fit and given a calibration dose and a spatial resolution. This way, we performed a 3D reconstruction of a dosimeter gel.

On the Selection of Region of Interest in Measurement of Cardiac Magnetic Resonance Imaging T2* Value in Thalassemia Major Patients

Objectives: To investigate the correlation between T2* values of different regions of interest (ROIs) in myocardium with the means of semi quantitatively estimating the myocardiac iron content in the thalassemia major patients. In the same setting we tried to design a model to predict T2* value of interventricular septum (septum) based on T2* values of other convenient ROIs in myocardium. Methods: 130 patients underwent ECG-gated cardiac magnetic resonance imaging (MRI), and T2* values were measured in different ROIs. Full-thickness ROIs are drawn manually in septum, entire left ventricle (LV) wall, the region of the best visual conspicuity (sharp), and LV free wall. The relation between T2* values of these four regions are investigated. Depends on the grade of siderosis, the patients are divided into four groups; Severe: T2* ? 10, Moderate: 10 20. The statistical analysis carried out using Matlab R2015b. Results: In patients with the cardiac T2* ? 20, the statistical analysis confirms a significant correlation (? = 0.001) between T2* values of septum and the ROIs named above. Moreover, the statistical results become more concordant with decreasing T2* values. In addition, for patients with a T2* > 20, a weak correlation is noticed between T2* values of different ROIs. Three predictor models are provided to estimate T2* value of septum using T2* values of entire LV wall, sharp region, and LV free wall. Conclusions: The T2* values of the LV free wall and the entire LV wall are reliable alternatives to estimate the T2* value of septum. The predictor model based on T2* value of entire LV wall provides the most reproducible estimation.

Amplitude of low-frequency fluctuations in first-episode, drug-naïve depressive patients: A 5-year retrospective study.

Despite different treatments and courses of illness, depressive symptoms appear similar in bipolar disorder (BD) and major depressive disorder (MDD), causing BD with an onset of depressive episode being frequently misdiagnosed as MDD, and leading to inappropriate treatment and poor clinical outcomes. Therefore, there is an urgent need to explore underlying neural basis to distinguish BD from MDD. The medical records of 80 first-episode, drug-naïve depressive patients with an initial diagnosis of MDD and illness duration of at least 5 years were reviewed retrospectively for this study. Fourteen bipolar depressed patients with a diagnosis conversion from MDD to BD, 14 patients with diagnosis of MDD, and 14 healthy subjects demographically matched with the BD group, were selected to participate in the study. Firstly, we examined whether there were differences among the three groups in whole brain fALFF during resting state. Secondly, clusters showing group differences in fALFF in any two groups were chosen as regions of interest (ROI) and then correlation between clinical features and fALFF values of ROIs were calculated. The BD group showed increased fALFF in bilateral putamen relative to both the MDD group and controls, while the MDD group exhibited decreased fALFF in left superior frontal gyrus (SFG) relative to both the BD group and controls (p < 0.05, corrected). Positive correlations between abnormality in the putamen and symptom severity were observed (significant for the MDD group, p = 0.043; marginally significant for the BD group, p = 0.060/0.076). These results implicate that abnormalities of key regions in the striatum and prefrontal areas may be trait markers for BD and MDD.

Value of FDG-PET scans of non-demented patients in predicting rates of future cognitive and functional decline

The aim of this study was to examine the value of fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting subsequent rates of functional and cognitive decline among subjects considered cognitively normal (CN) or clinically diagnosed with mild cognitive impairment (MCI). Analyses of 276 subjects, 92 CN subjects and 184 with MCI, who were enrolled in the Alzheimer's Disease Neuroimaging Initiative, were conducted. Functional decline was assessed using scores on the Functional Activities Questionnaire (FAQ) obtained over a period of 36months, while cognitive decline was determined using the Alzheimer's disease Assessment Scale-Cognitive subscale (ADAS-Cog) and Mini-Mental State Examination (MMSE) scores. PET images were analyzed using clinically routine brain quantification software. A dementia prognosis index (DPI), derived from a ratio of uptake values in regions of interest known to be hypometabolic in Alzheimer's disease to regions known to be stable, was generated for each baseline FDG-PET scan. The DPI was correlated with change in scores on the neuropsychological examinations to examine the predictive value of baseline FDG-PET. DPI powerfully predicted rate of functional decline among MCI patients (t=5.75, p < 1.0E-8) and pooled N + MCI patient groups (t = 7.02, p < 1.0E-11). Rate of cognitive decline on MMSE was also predicted by the DPI among MCI (t = 6.96, p < 1.0E-10) and pooled N + MCI (t = 8.78, p < 5.0E-16). Rate of cognitive decline on ADAS-cog was powerfully predicted by the DPI alone among N (p < 0.001), MCI (t = 6.46, p < 1.0E-9) and for pooled N + MCI (t = 8.85, p = 1.1E-16). These findings suggest that an index, derivable from automated regional analysis of brain PET scans, can be used to help predict rates of functional and cognitive deterioration in the years following baseline PET.

Abstract WP40: Quick CT Perfusion Evaluation of Leptomeningeal Collateral Circulation: Single Cortical CBV-ROI

Good collateral circulation (CC) is a strong outcome predictor in acute stroke patients. CT angiography (CTA) is wide-world available but does not provide accurate information about parenchymal status. CT perfusion (CTP) is frequently used to determine ischemic core and tissue at risk. Our aim was to identify an easy and quick method to evaluate CC status by CTP. Methods: Consecutive ischemic stroke patients &lt;8h from symptoms onset evaluated for reperfusion therapies were studied. Non-contrast CT, CTP and multiphase CTA were performed. Patients with confirmed M1-MCA or TICA occlusion on CTA were included. CC evaluation was determined by multiphase CTA (mCTA) according to the Calgary CC Scale and classified as poor (grades 0-2) or good (grades 3-5). In CTP maps, one single ipsi- and contralateral regions of interest (ROI) were defined in the MCA cortical territory (M4, M5, M6). We studied the association of absolute and relative to contralateral ROI-CTP values with CC degree determined by mCTA. Results: 33 patients were included, median NIHSS 17.5 (2-22). Twenty-five patients (75.8%) presented a M1 and 8 (24.2%) a TICA occlusion. On mCTA, 27 (81.8%) patients presented with a favourable CC status and 6 (18.2%) with poor CC. Mean ROI values in the ischemic MCA territory were: CBV 3.5±1.5 ml/100mg, CBF 46.9±29.3 ml/100mg/min, MTT 8.1±3.1 s, Tmax 23.2±4.4 s. In the contralateral non-ischemic MCA, the mean ROI values were: CBV 3.48±1.4, CBF 66.5±32.7, MTT 5.6±2.3, Tmax 20.4±4.8. Absolute and relative CBV-ROI data (relCBV= ischemic CBV value / contralateral CBV value) were the only values significantly associated with CC status on mCTA (good CC mean CBV: 3.8 ml/100g VS poor CC mean CBV: 1.9, p=0.006; good CC mean relCBV 1.1 vs poor CC mean relCBV 0.6, p=0.019). A ROC curve defined 2.5 ml/100mg as the better cut-off point of ROI-CBV that identified patients with good CC status (sensitivity 96%, specificity 84%, VPP 0.96, VPN 0.83). Patients with a ROI-CBV &gt;2.5 presented lower median NIHSS after 24 hours (4 vs 18, p= 0.012) and smaller mean infarct volume on control CT (27.9 vs 88.3, p=0.021). Conclusion: A single cortical ROI-CBV allows an easy and quick accurate evaluation of collateral circulation in CTP. ROI-CBV&gt;2.5 ml/100mg is related to good clinical and radiological outcomes.

Pulmonary Perfusion Changes as Assessed by Contrast-Enhanced Dual-Energy Computed Tomography after Endoscopic Lung Volume Reduction by Coils

Background: Endoscopic lung volume reduction by coils (LVRC) is a recent treatment approach for severe emphysema. Furthermore, dual-energy computed tomography (DECT) now offers a combined assessment of lung morphology and pulmonary perfusion. Objectives: The aim of our study was to assess the impact of LVRC on pulmonary perfusion with DECT. Methods: Seventeen patients (64.8 ± 6.7 years) underwent LVRC. DECT was performed prior to and after LVRC. For each patient, lung volumes and emphysema quantification were automatically calculated. Then, 6 regions of interest (ROIs) on the iodine perfusion map were drawn in the anterior, mid, and posterior right and left lungs at 4 defined levels. The ROI values were averaged to obtain lung perfusion as assessed by the lung's iodine concentration (C_Lung, μg·cm^-3). The C_Lung values were normalized using the left atrial iodine concentration (C_LA) to take into account differences between successive DECT scans. Results: The 6-min walk distance (6MWD) improved significantly after the procedure (p = 0.0002). No lung volume changes were observed between successive DECT scans for any of the patients (p = 0.32), attesting the same suspended inspiration. After LVRC, the emphysema index was significantly reduced in the treated lung (p = 0.0014). Lung perfusion increased significantly adjacent to the treated areas (C_Lung/C_LA from 3.4 ± 1.7 to 5.6 ± 2.2, p < 0.001) and in the ipsilateral untreated areas (from 4.1 ± 1.4 to 6.6 ± 1.7, p < 0.001), corresponding to a mean 65 and 61% increase in perfusion, respectively. No significant difference was observed in the contralateral upper and lower areas (from 4.4 ± 1.9 to 4.8 ± 2.1, p = 0.273, and from 4.9 ± 2.0 to 5.2 ± 1.7, p = 0.412, respectively). A significant correlation between increased 6MWD and increased perfusion was found (p = 0.0027, R² = 0.3850). Conclusions: Quantitative analysis based on DECT acquisition revealed that LVRC results in a significant increase in perfusion in the coil-free areas adjacent to the treated ones, as well as in the ipsilateral untreated areas. This suggests a possible role for LVRC in the improvement of the ventilation/perfusion relationship.

Cognitive and anatomical correlates of anosognosia in amnestic mild cognitive impairment and early-stage Alzheimer's disease.

Anosognosia is a common feature in Alzheimer's disease (AD). The brain substrates of anosognosia are not fully understood, and less is known about the cognitive substrates of anosognosia in prodromal and early stages of AD. Fourty-seven patients with amnestic-type mild cognitive impairment (aMCI) (n = 26) and early-stage AD (n = 21) were included, and Clinical Insight Rating Scale and Anosognosia Questionnaire for Dementia (AQ-D) were used to assess anosognosia. A detailed neuropsychological battery was administered; each patient underwent a structural magnetic resonance imaging (MRI). Correlation between anosognosia and performance in individual cognitive domains as well as correlation between anosognosia and cortical thickness values in regions of interest were assessed. Performance of the anosognosic patients in Digit Ordering Test (DOT), Digit Span Backwards, and Clock Drawing Test (CDT) was significantly worse compared to non-anosognosic patients in the total study population and in the aMCI subgroup but not in AD group. AQ-D scores negatively correlated with Mini-Mental State Examination (MMSE), California Verbal Learning Test (CVLT), Digit Span Backwards and CDT scores in total group and MMSE, CVLT, DOT, and Digit Span Backwards scores in the aMCI group. No significant correlations were found between cortical thickness measurements and AQ-D scores in any of the patient populations. Anosognosia was associated with episodic memory, working memory, and executive functions in the total population and aMCI group, but no association was found in early-stage AD patients. Anosognosia in the early stages of AD may be related with non-structural changes such as hypoconnectivity rather than structural changes.

Metal Artifact Reduction in Cone-Beam Computed Tomography for Head and Neck Radiotherapy.

To evaluate a method for reducing metal artifacts, arising from dental fillings, on cone-beam computed tomography images. A projection interpolation algorithm is applied to cone-beam computed tomography images containing metal artifacts from dental fillings. This technique involves identifying metal regions in individual cone-beam computed tomography projections and interpolating the surrounding values to remove the metal from the projection data. Axial cone-beam computed tomography images are then reconstructed, resulting in a reduction in the streak artifacts produced by the metal. Both phantom and patient imaging data are used to evaluate this technique. The interpolation substitution technique successfully reduced metal artifacts in all cases. Corrected images had fewer or no streak artifacts compared to their noncorrected counterparts. Quantitatively, regions of interest containing the artifacts showed reduced variance in the corrected images versus the uncorrected images. Average pixel values in regions of interest around the metal object were also closer in value to nonmetal regions after artifact reduction. Artifact correction tended to perform better on patient images with less complex metal objects versus those with multiple large dental fillings. The interpolation substitution is potentially an efficient and effective technique for reducing metal artifacts caused by dental fillings on cone-beam computed tomography image. This technique may be effective in reducing such artifacts in patients with head and neck cancer receiving daily image-guided radiotherapy.

Diffusion Tensor Imaging of White Matter Injury Caused by Prematurity-Induced Hypoxic-Ischemic Brain Damage.

BackgroundThis investigation aimed to evaluate changes in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of white matter injury (WMI) in preterm neonates with hypoxic-ischemic encephalopathy (HIE) using diffusion tension imaging (DTI).Material/MethodsThirty-eight neonates less than 37 weeks of gestation with leukoencephalopathy (as observation group) and 38 full-term infants with no leukoencephalopathy (as control group) were selected from the Neonatal Care Center in Taian Central Hospital from January 2012 to December 2013. A DTI scan was obtained within 1 week after birth.ResultsIn the observation group, on both sides the ADC values in regions of interest (ROI) of white matter, lesions were greater and FA values were lower than in the control group. ADC and FA values in genu and splenum of corpus callosum were statistically different between the mild and severe injury groups (p<0.05).ConclusionsThis study demonstrates that DTI provides sensitive detection and early diagnosis of WMI in brains of premature infants with HIE.

Apparent diffusion coefficient (ADC) measurement in ovarian tumor: Effect of region-of-interest methods on ADC values and diagnostic ability.

To investigate the difference in apparent diffusion coefficient (ADC) measurements of differently shaped regions of interest (ROIs) in ovarian tumors, and to investigate the diagnostic ability of differently shaped ROIs in differentiating benign from malignant ovarian tumors. Fifty-four patients with ovarian tumors with a solid component were evaluated. The patients underwent magnetic resonance (MR) examinations including diffusion-weighted imaging using a 3.0T MR system. Two readers measured ADCs using four ROI methods: freehand, square, round, and five small round ROIs. The interclass correlation coefficient (ICC) and repeated-measures analysis of variance were used to assess their measurement reliability and to compare ADCs for each ROI method. Receiver operating characteristic curve analysis and unpaired t-test on each ROI were used to differentiate benign and malignant ovarian tumors and assess the diagnostic ability. All ROI methods except the square ROI (0.56) showed good or excellent correlations (0.70-0.91). Minimum and mean ADC values differed significantly between the ROIs (P < 0.05). When using the freehand ROI, the minimum and mean ADC values were the lowest and highest, respectively. The optimal cutoff minimum and mean ADC values of each ROI for differentiating benign and malignant tumors were 0.81-1.06 × 10(-3) mm(2) /s and 1.15-1.52 × 10(-3) mm(2) /s, respectively. The areas under the curve showed no significant differences among the ADCs in the different ROI methods (P > 0.05). Minimum and mean ADCs from all ROIs showed significant differences between benign and malignant tumors (P < 0.05). The ROI shape influences ADC values and the optimal cutoff ADC values for differentiating benign from malignant ovarian tumors.

Optimal Target Region for Subject Classification on the Basis of Amyloid PET Images.

Classification of subjects on the basis of amyloid PET scans is increasingly being used in research studies and clinical practice. Although qualitative, visual assessment is currently the gold standard approach, automated classification techniques are inherently more reproducible and efficient. The objective of this work was to develop a statistical approach for the automated classification of subjects with different levels of cognitive impairment into a group with low amyloid levels (AβL) and a group with high amyloid levels (AβH) through the use of amyloid PET data from the Alzheimer Disease Neuroimaging Initiative study. In our framework, an iterative, voxelwise, regularized discriminant analysis is combined with a receiver operating characteristic approach that optimizes the selection of a region of interest (ROI) and a cutoff value for the automated classification of subjects into the AβL and AβH groups. The robustness, spatial stability, and generalization of the resulting target ROIs were evaluated by use of the standardized uptake value ratio for (18)F-florbetapir PET images from subjects who served as healthy controls, subjects who had mild cognitive impairment, and subjects who had Alzheimer disease and were participating in the Alzheimer Disease Neuroimaging Initiative study. We determined that several iterations of the discriminant analysis improved the classification of subjects into the AβL and AβH groups. We found that an ROI consisting of the posterior cingulate cortex/precuneus and the medial frontal cortex yielded optimal group separation and showed good stability across different reference regions and cognitive cohorts. A key step in this process was the automated determination of the cutoff value for group separation, which was dependent on the reference region used for the standardized uptake value ratio calculation and which was shown to have a relatively narrow range across subject groups. We developed a data-driven approach for the determination of an optimal target ROI and an associated cutoff value for the separation of subjects into the AβL and AβH groups. Future work should include the application of this process to other datasets to facilitate the determination of the translatability of the optimal ROI obtained in this study to other populations. Ideally, the accuracy of our target ROI and cutoff value could be further validated with PET-autopsy data from large-scale studies. It is anticipated that this approach will be extremely useful for the enrichment of study populations in clinical trials involving putative disease-modifying therapeutic agents for Alzheimer disease.

Validation of a simultaneous PET/MR system model for PET simulation using GATE.

Simultaneous PET/MR acquisition shows promise in a range of applications. Simulation using GATE is an essential tool that allows obtaining the ground truth for such acquisitions and therefore helping in the development and the validation of innovative processing methods such as PET image reconstruction, attenuation correction and motion correction. The purpose of this work is to validate the GATE simulation of the Siemens Biograph mMR PET/MR system. A model of the Siemens Biograph mMR was developed. This model includes the geometry and spatial positioning of the crystals inside the scanner and the characteristics of the detection process. The accuracy of the model was tested by comparing, on a real physical phantom study, GATE simulated results to reconstructed PET images using measured results obtained from a Siemens Biograph mMR system. The same parameters such as the acquisition time and phantom position inside the scanner were fixed for our simulations. List-mode outputs were recovered in both cases and reconstructed using the OPL-EM algorithm. Several parameters were used to compare the two reconstructed images such as profile comparison, signal-to-noise ratio and activity contrast analysis. Finally patient acquired MR images were segmented and used for the simulation of corresponding PET images. The simulated and acquired sets of reconstructed phantom images showed close emission values in regions of interest with relative differences lower than 5%. The scatter fraction was within a <3% agreement. Close matching of profiles and contrast indices were obtained between simulated and corresponding acquired PET images. Our results indicate that the GATE developed Biograph mMR model is accurate in comparison to the real scanner performance and can be used for evaluating innovative processing methods for applications in clinical PET/MR protocols.

Evaluation of bone involvement in patients with Gaucher disease: a semi-quantitative magnetic resonance imaging method (using ROI estimation of bone lesion) as an alternative method to semi-quantitative methods used so far.

The aim of this study was to evaluate bone involvement in patients with Gaucher disease (GD) and to propose a novel semi-quantitative magnetic resonance imaging (MRI) staging. MRI of the lumbar spine, femur, and tibia was performed in 24 patients with GD and 24 healthy controls. We also measured circulating levels of C-C motif ligand-3 (CCL-3) chemokine, C-telopeptide of collagen type-1 (CTX), and tartrate-resistant acid phosphatase isoform type-b (TRACP-5b). We used the following staging based on MRI data: stage I: region of interest (ROI) 1/2 of normal values and bone infiltration up to 30%; stage II: ROI 1/3 of normal values and bone infiltration from 30 to 60%; stage III: ROI 1/4 of normal values and bone infiltration from 60% to 80%; and stage IV: detection of epiphyseal infiltration, osteonecrosis and deformity regardless of the ROI's values. All but two patients had abnormal MRI findings: 9 (37.5%), 6 (25%), 3 (12.5%), and 4 (16.7%) had stages I-IV, respectively. Patients with GD had elevated chitotriosidase, serum TRACP-5b, and CCL-3 levels (P<0.001). We propose an easily reproducible semi-quantitative scoring system and confirm that patients with GD have abnormal MRI bone findings and enhanced osteoclast activity possibly due to elevated CCL-3.

2090662 Shear Wave Elastography - Four Essential Color Map Patterns To Rule Out Breast Malignancy

Shear wave elastography (SWE) is a non-invasive imaging technique which provides quantitative tissue elasticity data on breast lesions in addition to conventional ultrasonography (US). The aims of this study are to define the simple color map patterns to rule out malignancy, and evaluate the relationship between SWE findings and biological features of the breast carcinoma in Asian population. This is a retrospective, single center study which included 103 women (age range, 21-91 years) with 104 solid breast lesions identified during routine US performed between June 2013 and May 2014. All breast lesions were subsequently confirmed either by cytological or histological examinations. Obtained SWE images were classified into four patterns: No color on elastography image (pattern 1), vague longitudinal artifact inside the lesion (pattern 2), positive findings only at the surrounding area (pattern 3), and positive findings both at the boundary and inside the lesion (pattern 4). Eligible lesions were then evaluated for the mean quantitative elasticity values in regions of interest (ROI) placed over the stiffest area and the fat area to obtain the tumor/fat SWE ratio (TFSWR). Among the 104 lesions, 44 were malignant and 60 were benign. Color map patterns 1, 2, 3, and 4 were observed in 32, 19, 18, 35 cases respectively. Both patterns 1 and 2 lesions were 100% benign, whereas patterns 3 and 4 included 72% and 89% malignancies respectively. The results for combined US and SWE yielded 100% sensitivity, 85% specificity, 83% positive predictive value, 100% negative predictive value. The mean TFSWR was 18.4±9.7 vs 3.2±5.8 (p<0.001) for malignant and benign lesions. No malignant lesion showed TFSWR of higher than 5, whereas 9 (15%) benign lesions were present within. The TFSWR and hormone receptor status, HER2 status, histological grade, invasive size, lymph node status were not statistically relevant. In addition to conventional US, SWE color map patterns of 1 and 2, and TFSWR of less than 5 excluded all the breast malignancies. SWE results were not associated with any of the biological features of breast carcinoma in Asian population.

Microscopic diffusion anisotropy in the human brain: Reproducibility, normal values, and comparison with the fractional anisotropy

Human neuroimaging of tissue microstructure, such as axonal density and integrity, is key in clinical and neuroscience research. Most studies rely on diffusion tensor imaging (DTI) and the measures derived from it, most prominently fractional anisotropy (FA). However, FA also depends on fiber orientation distribution, a more macroscopic tissue property. Recently introduced measures of so-called microscopic diffusion anisotropy, diffusion anisotropy on a cellular or microscopic level, overcome this limitation because they are independent of the orientation distributions of axons and fibers. In this study, we evaluate the feasibility of two measures of microscopic diffusion anisotropy IMA and MA indices, for human neuroscience and clinical research. Both indices reflect the eccentricity of the cells but while IMA also depends on the cell size, MA is independent of the cell size and, like FA, scaled between 0 and 1. In whole-brain measurements of a group of 19 healthy volunteers, we measured average values and variability, evaluated their reproducibility, both within and between sessions, and compared MA to FA values in selected regions-of-interest (ROIs). The within- and between-session comparison did not show substantial differences but the reproducibility was much better for the MA than IMA (coefficient of variation between sessions 10.5% vs. 28.9%). The reproducibility was less for MA than FA overall, but comparable in the defined ROIs and the average group sizes required for between-group comparisons was similar (about 60 participants for a relative difference of 5%). Group-averaged values of MA index were generally larger and showed less variation across white-matter brain ROIs than FA (mean±standard deviation of seven ROIs 0.83±0.10 vs. 0.58±0.13). Even in some gray-matter ROIs, MA values comparable to those of white matter ROIs were observed. Furthermore, the within-group variation of the values in white matter ROIs was lower for the MA compared to the FA (mean standard deviation over volunteers 0.038 vs. 0.049) which could be due to significant variability in the distribution of fiber orientation contributing to FA. These results indicate that MA (i) should be preferred to IMA, (ii) has a reproducibility and group-size requirements comparable to those of FA; (iii) is less sensitive to the fiber orientation distribution than FA; and (iv) could be more sensitive to differences or changes of the tissue microstructure than FA. R1.1

Iron Accumulation Is Not Homogenous among Patients with Parkinson's Disease.

Background. Iron is considered to lead to neurodegeneration and has been hypothesized as a possible cause of Parkinson's disease (PD). Susceptibility-weighted imaging (SWI) is a powerful tool to measure phase related iron content of brain. Methods. Twelve de novo patients with PD were recruited from the Movement Disorders Clinic, Department of Neurology, Loma Linda University. Twelve age- and sex-matched non-PD subjects were recruited from neurology clinic as controls. Using SWI, the phase related iron content was estimated from different brain regions of interest (ROIs). Results. There was a trend between increasing age and iron accumulation in the globus pallidus and putamen in all subjects. Iron accumulation was not significant in different ROIs in PD patients compared to controls after adjustment for age. Our data revealed heterogeneity of phase values in different brain ROIs among all subjects with an exaggerated trend at SN in PD patients. Conclusions. Our data suggest a nonhomogeneous pattern of iron accumulation in different brain regions among PD patients. Further studies are needed to explore whether this may correlate to the progression of PD. To our knowledge, this is the first study demonstrating the heterogeneity of iron accumulation in the brain, among patients with PD.