Quantitative MRI Analysis Research Articles

An International Randomized Clinical Trial Evaluating Bst-Cargel®, A Novel Scaffold For Cartilage Repair, Demonstrates Superiority of Repair When Compared with Microfracture Alone Treatment

An international RCT with 80 patients evaluating BST-CarGel®, a novel chitosan-based scaffold applied to a cartilage lesion, showed superiority to microfracture alone for both the degree of lesion filling and the quality of cartilage repair tissue at 12 months by quantitative MRI and microscopic analyses of biopsies. Equivalent safety and clinical improvement at 12 months was also demonstrated. An international, multicenter randomized clinical trial was conducted to evaluate the efficacy and safety of BST-CarGel® (Piramal Healthcare, Laval, Canada), for the repair of articular cartilage lesions, compared to microfracture alone. BST-CarGel® is a device composed of the biomaterial chitosan (polyglucosamine) which is applied over a microfractured lesion. 80 patients at international sites (Canada, Spain, South Korea) were randomized (1:1) to either BST-CarGel®+microfracture or microfracture alone. Enrolled patients were aged 18 to 55, with BMIs=30 and had a single, symptomatic, grade III or IV lesion on their femoral condyles. They followed standardized 12-week post-operative rehabilitation. Quantity and quality of cartilage repair tissue was assessed at 12 months using quantitative MRI techniques. Supplemental structural data (ICRS I and II Histology Scoring and Polarized Light Microscopy (PLM) scoring) was also obtained from elective osteochondral biopsies taken at an average of 13 months from 38 consenting patients. Clinical improvement was measured at 12 months using WOMAC and SF-36 questionnaires, and safety was evaluated by monitoring adverse events. Blinded MRI analysis demonstrated that BST-CarGel® met both primary endpoints by achieving statistical superiority for BST-CarGel® in greater % Lesion Fill (p=0.0105) and more cartilage-like repair tissue T2 values (p=0.0330) when compared with microfracture alone. WOMAC assessments for pain, stiffness and function yielded equivalent improvement for both groups at 12 months, which were statistically significant (p<0.0001) from baseline. Safety was comparable for both groups. When compared to microfracture, BST-CarGel® repair tissue showed improved ICRS macroscopic grading (p=0.0002) at second-look arthroscopy, superior collagen organization by PLM (p=0.0003), and improvements in most histological parameters (4/6 ICRS-I and 10/14 ICRS-II, with 8 at (p<0.05) or near significance (p<0.11)). When compared to microfracture alone, the treatment of focal cartilage lesions with BST-CarGel® resulted in greater quantity and superior quality of cartilage repair tissue at 12 months as demonstrated by multiple, independent indicators.

Novel Scaffold-Based BST-CarGel Treatment Results in Superior Cartilage Repair Compared with Microfracture in a Randomized Controlled Trial

Microfracture, the standard of care, is recognized to be an incomplete solution for cartilage damage. BST-CarGel, a chitosan-based medical device, is mixed with autologous whole blood and is applied to a microfractured cartilage lesion in which it physically stabilizes the clot and guides and enhances marrow-derived repair. An international, multicenter, randomized controlled trial was conducted to evaluate BST-CarGel treatment compared with microfracture alone in the repair of cartilage lesions in the knee. Eighty patients between the ages of eighteen and fifty-five years with a single, symptomatic focal lesion on the femoral condyles were randomized to BST-CarGel and microfracture treatment (n = 41) or microfracture treatment alone (n = 39). The primary end points of repair tissue quantity and quality at twelve months were assessed by quantitative three-dimensional magnetic resonance imaging measuring the degree of lesion filling and T2 relaxation time with use of standardized one and twelve-month posttreatment scans. The secondary end point at twelve months was clinical benefit determined with the Western Ontario and McMaster Universities Osteoarthritis Index. The tertiary end point was quality of life determined by the Short Form-36. Safety was assessed through the recording of adverse events. Patient baseline characteristics were similar in the two groups, although baseline lesion areas were slightly larger on quantitative magnetic resonance imaging for the BST-CarGel group compared with the microfracture group. Blinded quantitative magnetic resonance imaging analysis demonstrated that, at twelve months, when compared with microfracture treatment alone, BST-CarGel treatment met both primary end points by achieving statistical superiority for greater lesion filling (p = 0.011) and more hyaline cartilage-like T2 values (p = 0.033). The lesion filling values were 92.8% ± 2.0% for the BST-CarGel treatment group and 85.2% ± 2.1% for the microfracture treatment group, and the mean T2 values were 70.5 ± 4.5 ms for the BST-CarGel treatment group and 85.0 ± 4.9 ms for the microfracture treatment group. Western Ontario and McMaster Universities Osteoarthritis Index subscales for pain, stiffness, and function yielded equivalent improvement for both groups at twelve months, which were significant (p < 0.0001) from baseline. Treatment safety profiles were considered comparable. At twelve months, BST-CarGel treatment resulted in greater lesion filling and superior repair tissue quality compared with microfracture treatment alone. Clinical benefit was equivalent between groups at twelve months, and safety was similar.

Sustained clinical and structural benefit after joint distraction in the treatment of severe knee osteoarthritis

Treatment of severe osteoarthritis (OA) in relatively young patients is challenging. Although successful, total knee prosthesis has a limited lifespan, with the risk of revision surgery, especially in active young patients. Knee joint distraction (KJD) provides clinical benefit and tissue structure modification at 1-year follow-up. The present study evaluates whether this benefit is preserved during the second year of follow-up. Patients included in this study presented with end-stage knee OA and an indication for total knee replacement (TKR); they were less than 60 years old with a VAS pain ≥60mm (n=20). KJD was applied for 2 months (range 54-64 days) and clinical parameters assessed using the WOMAC questionnaire and VAS pain score. Changes in cartilage structure were measured using quantitative MRI, radiography, and biochemical analyses of collagen type II turnover (ELISA). Average follow-up was 24 (range 23-25) months. Clinical improvement compared with baseline (BL) was observed at 2-year follow-up: WOMAC improved by 74% (P<0.001) and VAS pain decreased by 61% (P<0.001). Cartilage thickness observed by MRI (2.35mm (95%CI, 2.06-2.65) at BL) was significantly greater at 2-year follow-up (2.78mm (2.50-3.09); P=0.03). Radiographic minimum joint space width (JSW) (1.1mm (0.5-1.7) at BL) was significantly increased at 2-year follow-up as well (1.7mm (1.1-2.3); P=0.03). The denuded area of subchondral bone visualized by MRI (22% (95%CI, 12.5-31.5) at BL) was significantly decreased at 2-year follow-up (8% (3.6-12.2); P=0.004). The ratio of collagen type II synthesis over breakdown was increased at 2-year follow-up (P=0.07). Clinical improvement by KJD treatment is sustained for at least 2 years. Cartilage repair is still present after 2 years (MRI) and the newly formed tissue continues to be mechanically resilient as shown by an increased JSW under weight-bearing conditions.

Prediction of Poor Outcome in Cerebellar Infarction by Diffusion MRI

Identification of patients with posterior fossa infarction at risk for neurological deterioration remains a challenge. MRI-based assessments of MCA infarction can predict poor outcome. Similar quantitative imaging measures after cerebellar stroke have not been studied. We tested the hypothesis that MRI-based volumetric assessment of cerebellar infarcts can provide reliable information for the prediction of poor outcome. We retrospectively identified 44 consecutive subjects (age 55.2 ± 13) with cerebellar stroke who underwent MRI with diffusion-weighted imaging (DWI) (median 63.7 h). Subjects were divided into poor (n = 13) and good outcomes (n = 31). Poor outcome was defined as having at least one of the following criteria: (1) mortality, (2) decompressive craniectomy, (3) ventriculostomy, and (4) decrease level of consciousness. DWI and cerebellar volume were defined on apparent diffusion coefficient maps. The ratio of the lesion volume to the whole cerebellum volume was calculated (rVolume). Logistic regression revealed that lesion volume and rVolume were associated with increased risk of poor outcome, even after adjusting for age and NIHSS (χ(2) = 8.2230, p < 0.0042; χ(2) = 8.3992, p < 0.0038, respectively). The receiver operating characteristic curve with age, NIHSS, and volume or rVolume achieved an AUC of 0.816 (95 % CI 0.678-0.955) and 0.831 (95 % CI 0.6989-0.9636), respectively. Quantitative volumetric measurement predicts poor outcome of cerebellar stroke patients, even when controlling for age and NIHSS. Quantitative analysis of diffusion MRI may assist in identification of patients with cerebellar stroke at highest risk of neurological deterioration. Prospective validation is warranted.

Local Patch Similarity Ranked Voxelwise STAPLE on Magnetic Resonance Image Hippocampus Segmentation

The segmentation and labeling of sub-cortical structures of interest are important tasks for the assessment of morphometric features in quantitative magnetic resonance (MR) image analysis. Recently, multi-atlas segmentation methods with statistical fusion strategy have demonstrated high accuracy in hippocampus segmentation. While, most of the segmentations rarely consider spatially variant model and reserve all segmentations. In this study, we propose a novel local patch-based and ranking strategy for voxelwise atlas selection to extend the original Simultaneous Truth and Performance Level Estimation (STAPLE) algorithm. The local ranking strategy is based on the metric of normalized cross correlation (NCC). Unlike its predecessors, this method estimates the fusion of each voxel patch-by-patch and makes use of gray image features as a prior. Validation results on 33 pairs of hippocampus MR images show good performance on the segmentation of hippocampus.

Generating color-coded anatomic muscle maps for correlation of quantitative magnetic resonance imaging analysis with clinical examination in neuromuscular disorders

Fatty infiltration of muscles may be seen in many neuromuscular disorders, including glycogen storage disease (GSD), muscular dystrophy, and amyotrophic lateral sclerosis. Recording pathologic involvement of musculature in these patients is cumbersome, given marked disease heterogeneity within each individual. We describe a novel method for simplifying this process and present its application in a patient with GSD type IIIa. A color-coded visual mapping tool was developed based on a commonly used spreadsheet platform. This tool depicts individual muscle groups as shapes linked to data cells corresponding to quantitative MRI-based measures of fatty infiltration and weakness assessed by physical examination. It allows for rapid evaluation and chronological comparison of all mapped muscle groups on a single graphical sheet, as well as assessment of response to therapy. This approach can be applied in any neuromuscular disorder where muscle function is assessed by clinical or imaging scores.

FRI0364 Neuropsychiatric manifestations in juvenile systemic lupus erythematosus (JSLE)

BackgroundThe nervous system affects children and adults with systemic lupus erythematosus (SLE) and is associated with a worse prognosis and elevated mortality. In juvenil onset SLE (jSLE) the prevalence of...

THU0160 White matter lesions are predominantly demyelinating in systemic lupus erythematosus. An support vector machines classification of texture parameters

BackgroundTexture analysis (TA) is a branch of image processing which seeks to reduce image information by extracting texture descriptors from the image. White matter hyperintensities (WMH) are frequently observed in...

SP0166 Joint Distraction and Cartilage Regeneration – What is the Basis for Structural Repair?

Knee joint distraction is an experimental treatment for knee OA, aimed at temporarily unloading the joint cartilage and subchondral bone by use of an external fixation frame. The technique proved...

Intravoxel incoherent motion model-based liver lesion characterisation from three b-value diffusion-weighted MRI

To evaluate intravoxel incoherent motion (IVIM) model-based liver lesion characterisation from three b-value diffusion-weighted imaging (DWI). The 1.5-T DWI data from a respiratory gated spin-echo echo-planar magnetic resonance imaging sequence (b = 0, 50, 800 s/mm(2)) were retrospectively analysed in 38 patients with different liver lesions. Conventional apparent diffusion coefficient ADC = ADC(0,800) as well as IVIM-based parameters D' = ADC(50,800), ADC_low = ADC(0,50), and f' were calculated voxel-wise. Sixty-one regions of interest in hepatocellular carcinomas (HCCs, n = 24), haemangiomas (HEMs, n = 11), focal nodular hyperplasias (FNHs, n = 11), and healthy liver tissue (REFs, n = 15) were analysed. Group differences were investigated using Student's t-test and receiver-operating characteristic (ROC) analysis. Mean values ± standard deviations of ADC, D', ADC_low (in 10(-5) mm(2)/s), and f' (in %) for REFs/FNHs/HEMs/HCCs were 130 ± 11/143 ± 27/168 ± 16/113 ± 25, 104 ± 12/123 ± 25/162 ± 18/102 ± 23, 518 ± 66/437 ± 97/268 ± 69/283 ± 120, and 18 ± 3/14 ± 4/6 ± 3/9 ± 5, respectively. Differences between lesions and REFs were more significant for IVIM-based parameters than for conventional ADC. ROC analysis showed the best discriminability between HCCs and FNHs for ADC_low and f' and between HEMs and FNHs or HCCs for D'. Three instead of two b-value DWI enables a numerically stable and voxel-wise IVIM-based analysis for improved liver lesion characterisation with tolerable acquisition time. • Quantitative analysis of diffusion-weighted MRI helps liver lesion characterisation. • Analysis of intravoxel incoherent motion is superior to apparent diffusion coefficient determination. • Only three b-values enable separation of diffusion and microcirculation effects. • The method presented is numerically stable, with voxel-wise results and short acquisition times.

1081Constrictive Pericarditis in the Modern Cardiology Era Quantitative Analysis of Constrictive Physiology using Four-Dimensional MRI

Objectives: Accurate diagnosis of constrictive pericarditis (CP) is a well-recognized clinical challenge. Since magnetic resonance imaging (MRI) provides high resolution assessment of ventricular volumes, we sought to investigate left ventricular (LV) and right ventricular (RV) time-volume curve using four-dimensional MRI (4D MRI) in patients with CP. Methods: Fourteen patients with CP who had undergone surgery for pericardiectomy and 10 normal subjects were included. Three dimensional MRI covering the whole myocardium in the short axis projection was performed. LV and RV volumes were evaluated over the whole cardiac cycle to generate a four-dimensional MRI dataset for assessment of ventricular time volume curve yielding systolic function and filling parameters: end-diastolic and end-systolic volume, ejection fraction, filling time, early and late filling volume, E/A ratio, peak filling rate (PFR), and time to peak filling rate (TPFR). Results: In patients compared with normal subjects, LV and RV end-diastolic and end-systolic volumes were decreased (all P < 0.05), but biventricular ejection fraction was similar. The filling time of both ventricles was significantly shorter (both P < 0.001). In early diastole, LV and RV filling volumes were increased (P = 0.004, P < 0.001; respectively), in late diastole; however, LV and RV filling volumes were reduced (both P < 0.001). Biventricular E/A ratio and PFR were higher (all P < 0.001) and TPFR of the right ventricle was lower (P = 0.02) in patients compared with normal subjects. Conclusion: In patients with CP quantitative 4D MRI analysis provides reduction in end-diastolic and end-systolic volumes and demonstrated a typical hemodynamic response. In early diastole both ventricles have an increased filling, in late diastole, however; the constricted physiology allowed only a slight ventricular filling.

Abstract 2416: Weekly EZN-2208 (pegylated SN-38) in combination with bevacizumab in patients with refractory solid tumors.

Abstract Background: Anti-angiogenic therapies such as bevacizumab (Bev) have been shown to up-regulate hypoxia-inducible factor-1α (HIF-1α), a possible mechanism of resistance. Camptothecin analogues, including SN-38, have been shown to reduce the expression and transcriptional activity of HIF-1α in preclinical models. Thus, co-administration of pegylated SN 38 (EZN 2208) could offset the induction of HIF-1α following administration of Bev, resulting in synergistic anti-tumor effects. We are conducting a trial of the combination of EZN 2208 (E) with Bev in patients with refractory solid tumors to determine the safety and tolerability of the combination, and to evaluate modulation of HIF-1α protein in tumor biopsies following administration of study drugs. Methods: Eligible pts have refractory advanced solid tumors that have progressed following standard therapy; ≥ 18 yrs of age; ECOG PS 0-2; adequate organ function. Bev at 5mg/kg is administered on D-7 and D15 for cycle 1 only and on D1, 15 for each subsequent cycle; q28d cycles. E(9mg/kg) is administered on D1, 8, and 15. Tumor biopsies and dynamic contrast enhanced MRI (DCE-MRI) are obtained on D1 prior to EZN administration (7 days post Bev) and on C2D15 post Bev and E. An additional DCE-MRI is also performed at baseline prior to Bev on D-7. Tumor biopsies are analyzed for HIF-1α protein levels using a validated immunoassay, and HIF-1α response genes, Hexokinase 2(HK), vascular endothelial growth factor A(VEGF), pyruvate dehydrogenase kinase, isozyme 1(PDK1), carbonic anhydrase IX(CA9), solute carrier family 2 (GLUT1), are assessed using RTPCR. Results: Twelve pts have been enrolled to date; median age 50 (range 27-76 yrs); median # prior therapies 3 (1-6); Dx: Soft tissue sarcoma (4), colorectal cancer (2), parotid gland cancer (1), malignant hurthle cell tumor (1), HCC (1), melanoma (1), gastrointestinal stromal tumor (1), Head and neck cancer (1). Grade 3/4 toxicities (#pts): neutropenia (8), leucopenia (3), lymphopenia (2), hypertension (1). Eight pts are evaluable for response; prolonged stable disease was observed in 2 pts: HCC 16 cycles, desmoplastic round cell tumor 7 cycles. HIF-1α protein and mRNA levels of HIF-1α dependent genes were assessed in 5 pts who had paired biopsies. Reduction in HIF-1α protein levels compared to baseline (post Bev alone) was seen in 4 of 5 pts (range 24% - 64%), with evidence of modulation of mRNA in 3 of 5 pt tumors evaluated. Quantitative analysis of DCE MRI from 3 pts revealed changes in Ktrans and kep maps following drug administration. Correlation of observed changes with tumor response is ongoing. Conclusions: This clinical trial provides preliminary proof of mechanism demonstrating modulation of HIF-1α levels in tumors following administration of a camptothecin analog, EZN 2208. Accrual is ongoing to establish safety, efficacy, and further proof of target modulation. Citation Format: Woondong Jeong, Sook Ryun Park, Annamaria Rapisarda, Michelle Eugeni, Robert Kinders, Alice Chen, Giovanni Melillo, Baris Turkbey, James H. Doroshow, Shivaani Kummar. Weekly EZN-2208 (pegylated SN-38) in combination with bevacizumab in patients with refractory solid tumors. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2416. doi:10.1158/1538-7445.AM2013-2416

Quantitative neurofibrillary tangle density and brain volumetric MRI analyses in Alzheimer’s disease presenting as logopenic progressive aphasia

Neurofibrillary tangles (NFTs) are one of the key histological lesions of Alzheimer’s disease (AD) and are associated with brain atrophy. We assessed regional NFT density in 30 patients with AD, 10 of which presented as the logopenic variant of primary progressive aphasia (lvPPA) and 20 that presented as dementia of the Alzheimer’s type (DAT). Regional grey matter volumes were measured using antemortem MRI. NFT density was significantly higher in left temporoparietal cortices in lvPPA compared to DAT, with no differences observed in hippocampus. There was a trend for the ratio of temporoparietal-to-hippocampal NFT density to be higher in lvPPA. The imaging findings mirrored the pathological findings, with smaller left temporoparietal volumes observed in lvPPA compared to DAT, and no differences observed in hippocampal volume. This study demonstrates that lvPPA is associated with a phenomenon of enhanced temporoparietal neurodegeneration, a finding that improves our understanding of the biological basis of lvPPA.

Automated chest wall line detection for whole‐breast segmentation in sagittal breast MR images

Breast magnetic resonance imaging (MRI) plays an important role in the clinical management of breast cancer. Computerized analysis is increasingly used to quantify breast MRI features in applications such as computer-aided lesion detection and fibroglandular tissue estimation for breast cancer risk assessment. Automated segmentation of the whole-breast as an organ from the other parts imaged is an important step in aiding lesion localization and fibroglandular tissue quantification. For this task, identifying the chest wall line (CWL) is most challenging due to image contrast variations, intensity discontinuity, and bias field. In this work, the authors develop and validate a fully automated image processing algorithm for accurate delineation of the CWL in sagittal breast MRI. The CWL detection is based on an integrated scheme of edge extraction and CWL candidate evaluation. The edge extraction consists of applying edge-enhancing filters and an edge linking algorithm. Increased accuracy is achieved by the synergistic use of multiple image inputs for edge extraction, where multiple CWL candidates are evaluated by the dynamic time warping algorithm coupled with the construction of a CWL reference. Their method is quantitatively validated by a dataset of 60 3D bilateral sagittal breast MRI scans (in total 3360 2D MR slices) that span the full American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) breast density range. Agreement with manual segmentation obtained by an experienced breast imaging radiologist is assessed by both volumetric and boundary-based metrics, including four quantitative measures. In terms of breast volume agreement with manual segmentation, the overlay percentage expressed by the Dice's similarity coefficient is 95.0% and the difference percentage is 10.1%. More specifically, for the segmentation accuracy of the CWL boundary, the CWL overlay percentage is 92.7% and averaged deviation distance is 2.3 mm. Their method requires ≈ 4.5 min for segmenting each 3D breast MRI scan (56 slices) in comparison to ≈ 35 min required for manual segmentation. Further analysis indicates that the segmentation performance of their method is relatively stable across the different BI-RADS density categories and breast volume, and also robust with respect to a varying range of the major parameters of the algorithm. Their fully automated method achieves high segmentation accuracy in a time-efficient manner. It could support large scale quantitative breast MRI analysis and holds the potential to become integrated into the clinical workflow for breast cancer clinical applications in the future.

Simultaneous experimental determination of labile proton fraction ratio and exchange rate with irradiation radio frequency power‐dependent quantitative CEST MRI analysis

Chemical exchange saturation transfer (CEST) imaging is sensitive to dilute proteins/peptides and microenvironmental properties, and has been increasingly evaluated for molecular imaging and in vivo applications. However, the experimentally measured CEST effect depends on the CEST agent concentration, exchange rate and relaxation time. In addition, there may be non-negligible direct radio-frequency (RF) saturation effects, particularly severe for diamagnetic CEST (DIACEST) agents owing to their relatively small chemical shift difference from that of the bulk water resonance. As such, the commonly used asymmetry analysis only provides CEST-weighted information. Recently, it has been shown with numerical simulation that both labile proton concentration and exchange rate can be determined by evaluating the RF power dependence of DIACEST effect. To validate the simulation results, we prepared and imaged two CEST phantoms: a pH phantom of serially titrated pH at a fixed creatine concentration and a concentration phantom of serially varied creatine concentration titrated to the same pH, and solved the labile proton fraction ratio and exchange rate per-pixel. For the concentration phantom, we showed that the labile proton fraction ratio is proportional to the CEST agent concentration with negligible change in the exchange rate. Additionally, we found the exchange rate of the pH phantom is dominantly base-catalyzed with little difference in the labile proton fraction ratio. In summary, our study demonstrated quantitative DIACEST MRI, which remains promising to augment the conventional CEST-weighted MRI analysis.

Abstract TP37: Prediction of Outcome in Cerebellar Infarction by Diffusion MRI

Background and Purpose — Early identification of patients at risk for neurological deterioration due to edema after stroke remains a challenge. MRI based volumetric assessments of infarct have been shown to predict poor outcome amongst patients with large middle cerebral artery infarcts. However, no such quantitative imaging measure exists to predict outcome following cerebellar stroke. In this study, we tested the hypothesis that volumetric assessment of cerebellar infarcts can provide reliable information for the prediction of neurological deterioration. Methods — We retrospectively identified forty-four consecutive subjects (age 55.2±13) with cerebellar stroke who underwent MRI with DWI (mean 63.7 hours). Subjects were divided into poor (n=13) and good outcomes (n=31). Subjects were classified in the poor outcome group according to at least one of the following criteria: (1) mortality (2) decompressive craniectomy (3) ventriculostomy (4) decrease of consciousness according to item 1a of the NIH stroke scale score (NIHSS). These poor outcomes represent mass effect of the cerebellar infarct. Lesion and cerebellar volume were defined on ADC maps. The ratio of the lesion volume to the whole cerebellum volume was calculated (rVolume). The predictive value of volume and rVolume was determined using ROC analysis. Results — Logistic regression revealed that rVolume was associated with increased risk of poor outcome, even after adjusting for age and NIHSS (χ2 =9.4449, p &lt; 0.0022). The logistic regression model with age, rVolume, and NIHSS achieved an AUC of 0.816 (95% CI: 0.678-0.955), while a regression model with age and NIHSS alone achieved an AUC of 0.711 (95% CI: 0.537-0.885). The difference in AUC between these models was not statistically significant (Z = 0.3816, p = NS). Conclusions — Quantitative measurement of rVolume predicts poor outcome of cerebellar stroke patients, even when controlling for age and NIHSS. Quantitative analysis of diffusion MRI may assist in identification of patients with cerebellar stroke at highest risk of life-threatening edema. Prospective validation is warranted.

Quantitative MRI Analysis of the Brain after Twenty-Two Years of Neuromyelitis Optica Indicates Focal Tissue Damage

Background: The long-term effect of neuromyelitis optica (NMO) on the brain is not well established. Methods: After 22 years of NMO, a patient’s brain was examined by quantitative T1- and T2-weighted mono- and biexponential diffusion and proton spectroscopy. It was compared to 3 cases with short-term NMO and 20 healthy subjects. Results: Although routine T1- and T2-weighted images appeared to be normal, quantitative T1-, T2- and diffusion-weighted magnetic resonance imaging identified areas with high diffusivity and altered relaxation time in ‘normal appearing white matter’ (NAWM). In such abnormal NAWM regions, biexponential diffusion analysis and quantitative spectroscopy indicated extracellular edema and axonal loss, respectively. Repeated analysis 6 months later identified the same alterations. Such patchy alterations were not detectable in the NAWM of the 3 cases with short-term NMO, and they were also not quantitatively different from the controls. Conclusion: After NMO of 22-year duration, metabolic changes, altered diffusivity and magnetic resonance relaxation features of patchy brain areas may suggest tissue damage in NAWM that persist for at least 6 months.

Characterizing Aging in the Human Brainstem Using Quantitative Multimodal MRI Analysis

Aging is ubiquitous to the human condition. The MRI correlates of healthy aging have been extensively investigated using a range of modalities, including volumetric MRI, quantitative MRI (qMRI), and diffusion tensor imaging. Despite this, the reported brainstem related changes remain sparse. This is, in part, due to the technical and methodological limitations in quantitatively assessing and statistically analyzing this region. By utilizing a new method of brainstem segmentation, a large cohort of 100 healthy adults were assessed in this study for the effects of aging within the human brainstem in vivo. Using qMRI, tensor-based morphometry (TBM), and voxel-based quantification (VBQ), the volumetric and quantitative changes across healthy adults between 19 and 75 years were characterized. In addition to the increased R2* in substantia nigra corresponding to increasing iron deposition with age, several novel findings were reported in the current study. These include selective volumetric loss of the brachium conjunctivum, with a corresponding decrease in magnetization transfer and increase in proton density (PD), accounting for the previously described “midbrain shrinkage.” Additionally, we found increases in R1 and PD in several pontine and medullary structures. We consider these changes in the context of well-characterized, functional age-related changes, and propose potential biophysical mechanisms. This study provides detailed quantitative analysis of the internal architecture of the brainstem and provides a baseline for further studies of neurodegenerative diseases that are characterized by early, pre-clinical involvement of the brainstem, such as Parkinson’s and Alzheimer’s diseases.

Quantitative MRI analysis of salivary glands in sickle cell disease

The purpose of this prospective study was to characterize the MR relaxometric features of the major salivary glands in patients with sickle cell disease (SCD). 15 patients with SCD (aged 19.8-43.6 years) and 12 controls were imaged with the mixed turbo-spin echo pulse sequence. The major salivary glands were manually segmented and T1, T2 and secular T2 relaxometry histograms were modelled with Gaussian functions. Shortened T1 relaxation times were seen solely in the submandibular glands of patients with SCD (747.5±54.8 ms vs 807.1±38.3 ms, p<0.001). Slight T2 and secular T2 shortening were seen in the parotid gland; however, this difference was not significant (p=0.07). The sublingual gland showed no changes under MR relaxometry. There was no difference in glandular volumes, and no correlation was demonstrated between history of blood transfusion and salivary gland relaxometry. Patients with SCD exhibited changes in quantitative MRI T1 relaxometry histograms of the submandibular glands.

Brain magnetic resonance image segmentation based on an adapted non-local fuzzy c -means method

Intensity inhomogeneities cause considerable difficulties in the quantitative analysis of magnetic resonanceimages (MRIs). Consequently, intensity inhomogeneities estimation is a necessary step before quantitative analysis of MR data can be undertaken. This study proposes a new energy minimisation framework for simultaneous estimation of the intensity inhomogeneities and segmentation. The method was formulated by modifying the objective function of the standard fuzzy c -means algorithm to compensate for intensity inhomogeneities by using basis functions and to compensate for noise by using improved non-local information. The energy function depends on the coefficients of the basis functions, the membership ratios, the centroid of the tissues and an improved non-local information in the image. Intensity inhomogeneities estimation and image segmentation are simultaneously achieved by calculating the result of minimising this energy. The non-local framework has been widely used to provide non-local information; however, the traditional framework only considers the neighbouring patch information, which will lose information of the corner and end points. This study presents an improved non-local framework, which can contain the corner and end points region information. Experimental results on both real MRIs and simulated MR data show that the authors method can obtain more accurate results when segmenting images with bias field and noise.