Conventional T2-weighted Imaging Research Articles

On the role of neuronal magnetic susceptibility and structure symmetry on gradient echo MR signal formation.

Phase images obtained by gradient-recalled echo (GRE) MRI provide new contrast in the brain that is distinct from that obtained with conventional T1-weighted and T2-weighted images. The results are especially intriguing in white matter where both signal amplitude and phase display anisotropic properties. However, the biophysical origins of these phenomena are not well understood. The goal of this article is to provide a comprehensive theory of GRE signal formation based on a realistic model of neuronal structure. We use Maxwell equations to find the distribution of magnetic field induced by myelin sheath and axon. We account for both anisotropy of neuronal tissue "magnetic micro-architecture" and anisotropy of myelin sheath magnetic susceptibility. Model describes GRE signal comprising of three compartments-axonal, myelin, and extracellular. Both axonal and myelin water signals have frequency shifts that are affected by the magnetic susceptibility anisotropy of long molecules forming lipid bilayer membranes. These parts of frequency shifts reach extrema for axon oriented perpendicular to the magnetic field and are zeros in a parallel case. Myelin water signal is substantially non-monoexponential. Both, anisotropy of neuronal tissue "magnetic micro-architecture" and anisotropy of myelin sheath magnetic susceptibility, are important for describing GRE signal phase and magnitude.

Usefulness of slice encoding for metal artifact correction (SEMAC) for reducing metallic artifacts in 3-T MRI

PurposeThe purpose of the study was to assess the usefulness of slice encoding for metal artifact correction (SEMAC) in 3.0-T magnetic resonance (MR) in minimizing metallic artifacts in patients with spinal prostheses. Materials and MethodsInstitutional review board approval and informed consent were obtained for this study. Twenty-seven spine MR scans were performed with metal artifact reduction SEMAC between May 2011 and July 2012 in patients with metallic devices. The MR scans were performed on a 3-T MR system (Achieva; Philips Healthcare, Best, the Netherlands) including SEMAC-corrected T2-weighted axial/sagittal images and two-dimensional fast spin echo (FSE) axial/sagittal images. The SEMAC-corrected images were compared to conventional T2-weighted FSE images. Two musculoskeletal radiologists qualitatively analyzed the images in terms of visualization of the pedicle, vertebral body, dural sac, intervertebral disc, intervertebral neural foramina, screws and metallic artifacts. The paired images were rated using a 5-point scale. P values less than .05 were considered to indicate statistically significant differences. ResultsThe SEMAC-corrected MR images significantly reduced the metal-related artifacts. The T2-weighted images with SEMAC sequences enabled significantly improved periprosthetic visualizations of the pedicle, vertebral body, dural sac and neural foramina, with the exception of the intervertebral disc (P<.05). In addition, there was significant improvement in prosthesis visualization (P<.05). ConclusionMR images with SEMAC can reduce metal-related artifacts, providing improved delineation of the prosthesis and periprosthetic region. However, for the evaluation of the intervertebral disc, the SEMAC-corrected MR images showed no significant benefits.

Quantitative multi-parameter mapping of R1, PD*, MT, and R2* at 3T: a multi-center validation

Multi-center studies using magnetic resonance imaging facilitate studying small effect sizes, global population variance and rare diseases. The reliability and sensitivity of these multi-center studies crucially depend on the comparability of the data generated at different sites and time points. The level of inter-site comparability is still controversial for conventional anatomical T1-weighted MRI data. Quantitative multi-parameter mapping (MPM) was designed to provide MR parameter measures that are comparable across sites and time points, i.e., 1 mm high-resolution maps of the longitudinal relaxation rate (R1 = 1/T1), effective proton density (PD*), magnetization transfer saturation (MT) and effective transverse relaxation rate (R2* = 1/T2*). MPM was validated at 3T for use in multi-center studies by scanning five volunteers at three different sites. We determined the inter-site bias, inter-site and intra-site coefficient of variation (CoV) for typical morphometric measures [i.e., gray matter (GM) probability maps used in voxel-based morphometry] and the four quantitative parameters. The inter-site bias and CoV were smaller than 3.1 and 8%, respectively, except for the inter-site CoV of R2* (<20%). The GM probability maps based on the MT parameter maps had a 14% higher inter-site reproducibility than maps based on conventional T1-weighted images. The low inter-site bias and variance in the parameters and derived GM probability maps confirm the high comparability of the quantitative maps across sites and time points. The reliability, short acquisition time, high resolution and the detailed insights into the brain microstructure provided by MPM makes it an efficient tool for multi-center imaging studies.

Pretransplant prediction of microvascular invasion in patients with hepatocellular carcinoma: Added value of diffusion-weighted magnetic resonance imaging

The goals of the meticulous selection of patients withhepatocellular carcinoma (HCC) for liver transplanta-tion (LT) are to minimize the incidence of tumor recur-rence after transplantation and to improve patients’survival. Tumor invasion into vascular structures is aknown risk factor for tumor recurrence after LT. Mac-rovascular invasion, which is defined as the presenceof a tumor thrombus in a hepatic or portal vein, canbe detected on preoperative cross-sectional imaging. Itis considered an absolute contraindication to LT. Con-versely, microvascular invasion (MVI) by definitioncan be definitively diagnosed only by histopathology.Several studies have shown that MVI is associatedwith HCC recurrence within 1 year of transplanta-tion.

Automated detection of white matter signal abnormality using T2 relaxometry: Application to brain segmentation on term MRI in very preterm infants

Hyperintense white matter signal abnormalities, also called diffuse excessive high signal intensity (DEHSI), are observed in up to 80% of very preterm infants on T2-weighted MRI scans at term-equivalent age. DEHSI may represent a developmental stage or diffuse microstructural white matter abnormalities. Automated quantitative assessment of DEHSI severity may help resolve this debate and improve neonatal brain tissue segmentation. For T2-weighted sequence without fluid attenuation, the signal intensity distribution of DEHSI greatly overlaps with that of cerebrospinal fluid (CSF) making its detection difficult. Furthermore, signal intensities of T2-weighted images are susceptible to magnetic field inhomogeneity. Increased signal intensities caused by field inhomogeneity may be confused with DEHSI. To overcome these challenges, we propose an algorithm to detect DEHSI using T2 relaxometry, whose reflection of the rapid changes in free water content provides improved distinction between CSF and DEHSI over that of conventional T2-weighted imaging. Moreover, the parametric transverse relaxation time T2 is invulnerable to magnetic field inhomogeneity. We conducted computer simulations to select an optimal detection parameter and to validate the proposed method. We also demonstrated that brain tissue segmentation is further enhanced by incorporating DEHSI detection for both simulated preterm infant brain images and in vivo in very preterm infants imaged at term-equivalent age.

Sensitivity and specificity of MRI for detecting facial nerve abnormalities in dogs with facial neuropathy

Idiopathic facial neuropathy in dogs is conventionally diagnosed by exclusion of structural and metabolic causes of a single cranial neuropathy. To investigate the reliability and validity of MRI for supporting...

Correlation of Intervertebral Disk T2* MRI Presentation with 3D Kinematics

Introduction The causes of low back pain (LBP) are poorly defined and indistinct; the most often implicated tissue as the origin for pain is the intervertebral disk (IVD)1,2. Traditionally, lumbar spine range of motion measurements and IVD gross morphology (from MR images) are used to assess spinal health, but largely fail to correlate well with pain or provide clinically useful patient stratification3,4,5. Due to the inadequacies of current imaging techniques in differentiating symptomatic versus nonsymptomatic changes, a new series of quantitative protocols is emerging6. Quantitative T2* relaxation time measurements probe biochemical properties of the tissues. T2* mapping techniques are employed for cartilage assessment, probing spatial collagen architecture in conjunction with water molecule mobility7. As a first step, the goal of this work is to correlate quantitative MR mapping of the IVD with 3D kinematic data to probe the relationship between disk biochemical properties and functional kinematic parameters. Materials and Methods Total 18 osteoligamentous cadaveric lumbar spines (L3-S1), acquired from the UofM Bequest Program (aveage: 53.2 ± 15.5 years; range: 21 to 71 years) were examined using conventional and quantitative MR imaging protocols and biomechanically exercised in the cardinal planes. MR imaging was performed on a Siemens 3T scanner (Magnetom Trio; Siemens Health care). Conventional T2-weighted sagittal anatomic images were acquired for Pfirrmann disk grading (Fig. 1A)8. T2* relaxation maps were obtained using [TR(ms): 500; TE(ms): 4.18, 11.32, 18.46, 25.60, 32.74, 39.88; Voxel Size(mm): 0.5 × 0.5 × 3.0, Slices: 33]. Quantitative T2* maps were calculated (MapIt, Siemens Health care) and mean T2* values were recorded using Osirix Imaging Software across five regions of interest (ROI) (Fig. 1B). Utilizing MATLAB (Mathworks Inc. Natick, MA), the central ROI mean relaxation value was evaluated in the coronal plane as the intensity changed from lateral to medial to lateral (Fig. 1C). Using a least squares method, the slope of the transition zone (ms/mm) between the annulus fibrosus and nucleus pulposus on each side was computed (Fig. 1D). The area underneath the curve was calculated and normalized to the width of the IVD (Fig. 1D). After imaging, the specimens were embedded in polymethylmethacrylate and tested in a six-axis Spine Kinetic Simulator (8821 Biopuls, Instron, Norwood, MA, USA). Pure moments of up to 7 Nm were applied sinusoidally (0.015 Hz). Three cycles were performed and the final cycle was analyzed. Load and moment data was collected at 100 Hz. Segmental displacements were recorded using a 3D visual motion analysis 5-camera system (Vicon MX-F40NIR, Vicon Motion Systems, Centennial, CO) capturing a four-ball infrared reflecting marker set attached to each vertebral body. Kinematic outcomes (ROM, Neutral Zone, NZ/ROM, Stiffness) were correlated with imaging parameters using Pearson correlation test with alpha acceptance of 0.05. Results The T2* relaxation measurements in the nucleus pulposus were significantly correlated with flexion stiffness ( p = 0.024) and lateral bending stiffness ( p = 0.021) wherein increased stiffness was associated with lower signal and higher Pfirrmann grade. The slope of the transition zone for the 54 disk samples was found to be correlated with the flexion stiffness ( p = 0.026), flexion range of motion ( p = 0.002), lateral bending stiffness ( p = 0.029), and lateral bending range of motion ( p = 0.0028). The area under the T2* intensity curves in the coronal plane was likewise found to be significantly correlated with following biomechanical measures: flexion stiffness ( p = 0.043), flexion range of motion (p = 0.014), lateral bending stiffness (p = 0.021), and lateral bending range of motion ( p = 0.023). Conclusion MR imaging of IVD using T2* relaxation measurements provide quantitative assessment of the disk's biochemical properties which is related to its biomechanical competence. This new methodology and analysis technique may provide enhanced quantitative data on the degenerative cascade which alters disk function and in some cases leads to painful outcomes. Limitations of this research include the biomechanical testing of cadaveric samples without musculature and their postmortem imaging at room temperature. Next, we aim to evaluate this relationship in human subjects and determine its clinical efficacy. This research linked kinematic data with quantitative T2* mapping of IVD from across the degenerative spectrum. By coupling quantitative MR imaging with functional kinematic outcomes, these data may improve patient stratification and targeted therapeutic intervention for patients suffering from LBP. I confirm having declared any potential conflict of interest for all authors listed on this abstract Yes Disclosure of Interest None declared Salminen. Spine 1999 Cheung. Spine 2009 Boden. Journal of Joint and Bone surgery 1990 Savage. Spine Journal 1997 Mimura. Spine 1994 Welsch. Skeletal Radiology 2011 Mamisch. Skeletal Radiology 2011 Pfirrmann. Spine 2001. Funding: NIH/NIAMS T32 AR050938

Evaluation of Automatic Measurement of the Intracranial Volume Based on Quantitative MR Imaging

Brain size is commonly described in relation to ICV, whereby accurate assessment of this quantity is fundamental. Recently, an optimized MR sequence (QRAPMASTER) was developed for simultaneous quantification of T1, T2, and proton density. ICV can be measured automatically within minutes from QRAPMASTER outputs and a dedicated software, SyMRI. Automatic estimations of ICV were evaluated against the manual segmentation. In 19 healthy subjects, manual segmentation of ICV was performed by 2 neuroradiologists (Obs1, Obs2) by using QBrain software and conventional T2-weighted images. The automatic segmentation from the QRAPMASTER output was performed by using SyMRI. Manual corrections of the automatic segmentation were performed (corrected-automatic) by Obs1 and Obs2, who were blinded from each other. Finally, the repeatability of the automatic method was evaluated in 6 additional healthy subjects, each having 6 repeated QRAPMASTER scans. The time required to measure ICV was recorded. No significant difference was found between reference and automatic (and corrected-automatic) ICV (P > .25). The mean difference between the reference and automatic measurement was -4.84 ± 19.57 mL (or 0.31 ± 1.35%). Mean differences between the reference and the corrected-automatic measurements were -0.47 ± 17.95 mL (-0.01 ± 1.24%) and -1.26 ± 17.68 mL (-0.06 ± 1.22%) for Obs1 and Obs2, respectively. The repeatability errors of the automatic and the corrected-automatic method were <1%. The automatic method required 1 minute 11 seconds (SD = 12 seconds) of processing. Adding manual corrections required another 1 minute 32 seconds (SD = 38 seconds). Automatic and corrected-automatic quantification of ICV showed good agreement with the reference method. SyMRI software provided a fast and reproducible measure of ICV.

MR T1ρ as an imaging biomarker for monitoring liver injury progression and regression: an experimental study in rats with carbon tetrachloride intoxication

Recently it was shown that the magnetic resonance imaging (MRI) T1ρ value increased with the severity of liver fibrosis in rats with bile duct ligation. Using a rat carbon tetrachloride (CCl(4)) liver injury model, this study further investigated the merit of T1ρ relaxation for liver fibrosis evaluation. Male Sprague-Dawley rats received intraperitoneal injection of 2 ml/kg CCl(4) twice weekly for up to 6 weeks. Then CCl(4) was withdrawn and the animals were allowed to recover. Liver T1ρ MRI and conventional T2-weighted images were acquired. Animals underwent MRI at baseline and at 2 days, 2 weeks, 4 weeks and 6 weeks post CCl(4) injection, and they were also examined at 1 week and 4 weeks post CCl(4) withdrawal. Liver histology was also sampled at these time points. Liver T1ρ values increased slightly, though significantly, on day 2, and then increased further and were highest at week 6 post CCl(4) insults. The relative liver signal intensity change on T2-weighted images followed a different time course compared with that of T1ρ. Liver T1ρ values decreased upon the withdrawal of the CCl(4) insult. Histology confirmed the animals had typical CCl(4) liver injury and fibrosis progression and regression processes. MR T1ρ imaging can monitor CCl(4)-induced liver injury and fibrosis. • MR T1ρ is a valuable imaging biomarker for liver injury/fibrosis. • Liver T1ρ was only mildly affected by oedema and acute inflammation. • Liver MR T1ρ decreased when liver fibrosis and injury regressed.

High Incidence of Radiation-Induced Cavernous Hemangioma in Long-Term Survivors Who Underwent Hematopoietic Stem Cell Transplantation with Radiation Therapy during Childhood or Adolescence

Radiation-induced cavernous hemangioma (RICH) is a late complication of cerebral radiation therapy. Long-term survivors of hematopoietic stem cell transplantation (HSCT) who underwent radiation therapy could be at increased risk for RICH. We investigated records of 68 patients who underwent HSCT during childhood or adolescence and were assessed by magnetic resonance imaging (MRI), including T2*-weighted imaging of the brain, annually for 5 years over a range of 6 to 29 years after HSCT. We developed a scoring and grading system for RICH to monitor the process and the progress of radiologic changes. Among the 68 patients investigated, 28 (41.2%) were diagnosed with CH. All 28 patients had received total body irradiation as a conditioning treatment for HSCT and/or cranial radiation therapy before HSCT as part of the treatment of their primary disease. RICH was diagnosed in none of the patients who did not receive radiation (n = 19), in 46.2% of those who received 6 to 12 Gy (n = 39), and in all of those who received 18 to 36 Gy (n = 10). Total RICH scores were correlated with higher radiation doses. Careful and long-term evaluation with MRI, including T2*-weighted imaging, is necessary for HSCT recipients who received radiation therapy before and/or during HSCT.

Chronic Multiple Sclerosis Lesions: Characterization with High-Field-Strength MR Imaging

To elucidate the mechanism of magnetic resonance (MR) imaging contrast in multiple sclerosis (MS) lesion appearance by using susceptibility-weighted imaging and to assess with histologic correlation the role of iron and myelin in generating this MR imaging contrast. Each patient provided written consent to a human subject protocol approved by an institutional review board. High-spatial-resolution susceptibility-weighted 7.0-T MR images were obtained in 21 patients with MS. Contrast patterns in quantitative phase and R2* images, derived from 7.0-T data, were investigated in 220 areas defined as chronic MS lesions on conventional T2-weighted fluid-attenuated inversion recovery, T2-weighted, and T1-weighted spin-echo images. The presence of positive or negative phase shifts (ie, decreased or increased MR frequency, respectively) was assessed in each lesion. In addition, postmortem MR imaging was performed at 7.0 T and 11.7 T, and its results were correlated with those of immunohistochemical staining specific for myelin, iron, and ferritin. The majority (133 [60.5%] of 220) of the identified lesions had a normal phase and reduced R2*. A substantial fraction of the lesions (84 [38.2%] of 220) had negative phase shift, either uniformly or at their rim, and a variety of appearances on R2* maps. These two lesion contrast patterns were reproduced in the postmortem MR imaging study. Comparison with histologic findings showed that, while R2* reduction corresponded to severe loss of both iron and myelin, negative phase shift corresponded to focal iron deposits with myelin loss. Combined analysis of 7.0-T R2* and phase data may help in characterizing the pathologic features of MS lesions. The observed R2* decreases suggest profound myelin loss, whereas negative phase shifts suggest a focal iron accumulation.

Improved Detection of Myocardial Involvement in Acute Inflammatory Cardiomyopathies Using T2 Mapping

T2-weighted cardiac magnetic resonance imaging is useful in diagnosing acute inflammatory myocardial diseases, such as myocarditis and tako-tsubo cardiomyopathy (TTCM). We hypothesized that quantitative T2 mapping could better delineate myocardial involvement in these disorders versus T2-weighted imaging. Thirty patients with suspected myocarditis or TTCM, referred for cardiac magnetic resonance imaging, who met established diagnostic criteria underwent myocardial T2 mapping. T2 values were averaged in involved and remote myocardial segments, both defined by a reviewer blinded to T2 data. In myocarditis, T2 was 65.2±3.2 ms in the involved myocardium versus 53.5±2.1 ms in the remote myocardium (P<0.001). In TTCM, T2 was 65.6±4.0 ms in the involved myocardium versus 53.6±2.7 ms in the remote segments (P<0.001). T2 values were similar across remote myocardial segments in patients and all myocardial segments in controls (P>0.05 for all). T2 maps provided diagnostic data even in patients with difficulty breath holding. A T2 cutoff of 59 ms identified areas of myocardial involvement, with sensitivity and specificity of 94% and 97%, respectively. T2 mapping revealed regions of abnormal T2 beyond those identified by wall motion abnormalities or late gadolinium-enhancement positivity. Conventional T2-weighted short tau inversion recovery images were uninterpretable in 7 patients because of artifact and unremarkable in 2 patients who had elevated T2 values. T2-prepared steady-state-free precession images showed areas of signal hyperintensity in only 17 of 30 patients. Quantitative T2 mapping reliably identifies myocardial involvement in patients with myocarditis and TTCM. T2 mapping delineated a greater extent of myocardial disease in both conditions compared with that identified by wall motion abnormalities, T2-weighted short tau inversion recovery imaging, T2-prepared steady-state-free precession, or late gadolinium enhancement. Quantitative T2 mapping warrants consideration as a robust technique to identify myocardial injury in patients with acute myocarditis or TTCM.

Multiparametric 3T Prostate Magnetic Resonance Imaging to Detect Cancer: Histopathological Correlation Using Prostatectomy Specimens Processed in Customized Magnetic Resonance Imaging Based Molds

We determined the prostate cancer detection rate of multiparametric magnetic resonance imaging at 3T. Precise one-to-one histopathological correlation with magnetic resonance imaging was possible using prostate magnetic resonance imaging based custom printed specimen molds after radical prostatectomy. This institutional review board approved prospective study included 45 patients (mean age 60.2 years, range 49 to 75) with a mean prostate specific antigen of 6.37 ng/ml (range 2.3 to 23.7) who had biopsy proven prostate cancer (mean Gleason score of 6.7, range 6 to 9). Before prostatectomy all patients underwent prostate magnetic resonance imaging using endorectal and surface coils on a 3T scanner, which included triplane T2-weighted magnetic resonance imaging, apparent diffusion coefficient maps of diffusion weighted magnetic resonance imaging, dynamic contrast enhanced magnetic resonance imaging and spectroscopy. The prostate specimen was whole mount sectioned in a customized mold, allowing geometric alignment to magnetic resonance imaging. Tumors were mapped on magnetic resonance imaging and histopathology. Sensitivity, specificity, positive predictive value and negative predictive value of magnetic resonance imaging for cancer detection were calculated. In addition, the effects of tumor size and Gleason score on the sensitivity of multiparametric magnetic resonance imaging were evaluated. The positive predictive value of multiparametric magnetic resonance imaging to detect prostate cancer was 98%, 98% and 100% in the overall prostate, peripheral zone and central gland, respectively. The sensitivity of magnetic resonance imaging sequences was higher for tumors larger than 5 mm in diameter as well as for those with higher Gleason scores (greater than 7, p <0.05). Prostate magnetic resonance imaging at 3T allows for the detection of prostate cancer. A multiparametric approach increases the predictive power of magnetic resonance imaging for diagnosis. In this study accurate correlation between multiparametric magnetic resonance imaging and histopathology was obtained by the patient specific, magnetic resonance imaging based mold technique.

Superficial siderosis of the central nervous system: MR findings with susceptibility-weighted imaging

We report three cases of superficial siderosis of the central nervous system examined with MR susceptibility-weighted imaging (SWI) technique additional to the conventional SE sequence. Deposition of hemosiderin on SWI images is thicker and far more conspicuous compare with conventional T2-weighted images. Additional intracerebral bleeds are evidenced on susceptibility-weighted images in all three cases, which provide possible clues to the underlining etiology of superficial siderosis.

MRI detection of tissue pathology beyond atrophy in Alzheimer's disease: Introducing T2-VBM

Voxel-based morphometry (VBM) of T1-weighted magnetic resonance (MR) images has been widely used to identify regional atrophy in neurodegenerative conditions such as Alzheimer's disease (AD). In theory, however, T2-weighting should be more sensitive to tissue pathology, though until recently, volumetric T2-weighted images were unavailable. We tested the hypothesis that T2-VBM would be more sensitive to grey matter pathology in AD than T1-VBM using the recently-developed SPACE acquisition, which provides true-3D, high-resolution T2-weighted images. This was contrasted to conventional T1-weighted MPRAGE images acquired at the same session and resolution. All of the atrophic regions identified with T1-VBM were also identified with T2-VBM. Additional abnormalities were, however, identified with T2-VBM and the distribution of these bore a striking resemblance to the distribution of amyloid plaque deposition in AD, suggesting that T2-VBM detects signal changes due to histopathology over and above those attributable to atrophy. In keeping with this hypothesis, the relevant statistical tests demonstrated that the difference in sensitivity was caused by an apparent change in T2-weighted signal intensity that was not present in T1-weighted images. These results suggest that T2-VBM has the potential to advance VBM beyond atrophy detection to more expansive applications in tissue pathology mapping.

Direct T2 Quantification of Myocardial Edema in Acute Ischemic Injury

To evaluate the utility of rapid, quantitative T2 mapping compared with conventional T2-weighted imaging in patients presenting with various forms of acute myocardial infarction. T2-weighted cardiac magnetic resonance (CMR) identifies myocardial edema before the onset of irreversible ischemic injury and has shown value in risk-stratifying patients with chest pain. Clinical acceptance of T2-weighted CMR has, however, been limited by well-known technical problems associated with existing techniques. T2 quantification has recently been shown to overcome these problems; we hypothesized that T2 measurement in infarcted myocardium versus remote regions versus zones of microvascular obstruction in acute myocardial infarction patients could help reduce uncertainty in interpretation of T2-weighted images. T2 values using a novel mapping technique were prospectively recorded in 16 myocardial segments in 27 patients admitted with acute myocardial infarction. Regional T2 values were averaged in the infarct zone and remote myocardium, both defined by a reviewer blinded to the results of T2 mapping. Myocardial T2 was also measured in a group of 21 healthy volunteers. T2 of the infarct zone was 69 ± 6 ms compared with 56 ± 3.4 ms for remote myocardium (p < 0.0001). No difference in T2 was observed between remote myocardium and myocardium of healthy volunteers (56 ± 3.4 ms and 55.5 ± 2.3 ms, respectively, p = NS). T2 mapping allowed for the detection of edematous myocardium in 26 of 27 patients; by comparison, segmented breath-hold T2-weighted short tau inversion recovery images were negative in 7 and uninterpretable in another 2 due to breathing artifacts. Within the infarct zone, areas of microvascular obstruction were characterized by a lower T2 value (59 ± 6 ms) compared with areas with no microvascular obstruction (71.6 ± 10 ms, p < 0.0001). T2 mapping provided consistent high-quality results in patients unable to breath-hold and in those with irregular heart rhythms, in whom short tau inversion recovery often yielded inadequate imaging. Quantitative T2 mapping reliably identifies myocardial edema without the limitations encountered by T2-weighted short tau inversion recovery imaging, and may therefore be clinically more robust in showing acute ischemic injury.

Texture-based quantification of lumbar intervertebral disc degeneration from conventional T2-weighted MRI

Disc degeneration quantification is important for monitoring the effects of new therapeutic methods, such as cell and growth factor therapy. Magnetic resonance (MR) image texture reflects biochemical and structural tissue properties and has been used for differentiating between normal and pathological status in a variety of medical applications. To investigate the suitability of textural descriptors for the quantification of intervertebral disc degeneration using conventional T2-weighted magnetic resonance images of the lumbar spine. A 3 Tesla scanner was used, and conventional T2- weighted MR images were obtained, and a total of 255 lumbar discs were analyzed. An atlas-based method was used for segmenting the disc regions from the images. A set of first and second order statistics describing texture of each region were calculated. The validity and reliability of these descriptors for disc degeneration severity quantification was tested through their correlation with patient age and qualitative clinical grading of degeneration severity. Texture quantification results were compared to a widely accepted method for disc degeneration quantification based on the measurement of disc's mean signal intensity. Out of the set of texture descriptors tested, two descriptors quantifying image intensity inhomogeneity, i.e. the grey level standard deviation and co-occurrence derived sum of squares displayed the strongest association to patient age and clinical grading of disc degeneration severity (P<0.001). This is attributed to these inhomogeneity descriptors' capability to capture the progressive loss of nucleus-annulus distinction in the degenerative progress. Statistical analysis indicates that these descriptors can effectively separate between early stages of degeneration. Quantitative measurements are highly repeatable (intraclass correlation >0.98). Inhomogeneity descriptors could be a valuable tool for tracking the evolution of disc degeneration and monitoring the response to treatment in a simple, precise and repeatable manner.

Volumetric fat-water separated T2-weighted MRI

Pediatric body MRI exams often cover multiple body parts, making the development of broadly applicable protocols and obtaining uniform fat suppression a challenge. Volumetric T2 imaging with Dixon-type fat-water separation might address this challenge, but it is a lengthy process. We develop and evaluate a faster two-echo approach to volumetric T2 imaging with fat-water separation. A volumetric spin-echo sequence was modified to include a second shifted echo so two image sets are acquired. A region-growing reconstruction approach was developed to decompose separate water and fat images. Twenty-six children were recruited with IRB approval and informed consent. Fat-suppression quality was graded by two pediatric radiologists and compared against conventional fat-suppressed fast spin-echo T2-W images. Additionally, the value of in- and opposed-phase images was evaluated. Fat suppression on volumetric images had high quality in 96% of cases (95% confidence interval of 80-100%) and were preferred over or considered equivalent to conventional two-dimensional fat-suppressed FSE T2 imaging in 96% of cases (95% confidence interval of 78-100%). In- and opposed-phase images had definite value in 12% of cases. Volumetric fat-water separated T2-weighted MRI is feasible and is likely to yield improved fat suppression over conventional fat-suppressed T2-weighted imaging.

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

OBJECTIVES:To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2‐weighted magnetic resonance imaging, spectroscopy and dynamic contrast‐enhanced magnetic resonance imaging in localizing and locally staging low‐risk prostate cancer.INTRODUCTION:Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low‐risk prostate cancer is based on clinical stage T1c or T2a, Gleason score ≤6, and prostate‐specific antigen (PSA) ≤10 ng/ml.METHODS:From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard.RESULTS:Sixteen patients (45.7%) had pathologically proven organ‐confined disease, 11 (31.4%) had positive surgical margin, 8 (28.9%) had extracapsular extension, and 3 (8.6%) presented with extracapsular extension and seminal vesicle invasion.Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy values for localizing low‐risk prostate cancer were 53.1%, 48.3%, 63.4%, 37.8% and 51.3% for transrectal ultrasound; 70.4%, 36.2%, 65.1%, 42.0% and 57.7% for amplitude Doppler ultrasound; 71.5%, 58.9%, 76.6%, 52.4% and 67.1% for magnetic resonance imaging; 70.4%, 58.7%, 78.4%, 48.2% and 66.7% for magnetic resonance spectroscopy; 67.2%, 65.7%, 79.3%, 50.6% and 66.7% for dynamic contrast‐enhanced magnetic resonance imaging, respectively.Sensitivity, specificity, PPV, NPV and accuracy values for detecting extracapsular extension were 33.3%, 92%, 14.3%, 97.2% and 89.7% for transrectal ultrasound and 50.0%, 77.6%, 13.7%, 95.6% and 75.7% for magnetic resonance imaging, respectively. For detecting seminal vesicle invasion, these values were 66.7%, 85.7%, 22.2%, 97.7% and 84.6% for transrectal ultrasound and 40.0%, 83.1%, 15.4%, 94.7% and 80.0% for magnetic resonance imaging.CONCLUSION:Although preliminary, our results suggest that imaging modalities have limited usefulness in localizing and locally staging clinically low‐risk prostate cancer.

Neural bases of executive dysfunctions in parkinson?s disease: a diffusion tensor imaging study

Event Abstract Back to Event Neural bases of executive dysfunctions in parkinson’s disease: a diffusion tensor imaging study Iwona Szatkowska1*, Ludwika Gawrys1, Artur Pilacinski2, Maciej Bielecki3, Ewa Piatkowska-Janko3, Tomasz Wolak4, Marcel Falkiewicz1, Renata Andrysiak5, Andrzej Friedman5 and Leszek Krolicki5 1 Nencki Institute of Experimental Biology, Poland 2 Hertie Institute for Clinical Brain Research, Germany 3 Warsaw University of Technology, Poland 4 Institute of Physiology and Pathology of Hearing, Poland 5 Medical University of Warsaw, Poland Diffusion tensor imaging (DTI) offers a unique opportunity to study the connectivity changes which accompany the cognitive dysfunctions in Parkinson’s disease (PD). The aim of the present study was to evaluate executive functions in non-demented patients with idiopathic PD, and to compare the fractional anisotropy (FA) values of PD patients with and without executive dysfunction. Twenty-six patients with PD participated in this study (Hoehn & Yahr' stages I and II). Patients were divided into two groups on the basis of their Wisconsin Card Sorting Test score (numbers of categories achieved). Magnetic resonance imaging was carried out with a 1.5-T scanner (GE Signa Excite). In addition to the conventional T2-weighted images, T1-weighted images and FA maps calculated from DTI were obtained. The imaging sequence for DTI was EPI-SE, TR/TE = 8300/110. Diffusion sensitization was carried out in 25 directions. The results showed significant FA reduction in the cingulate white matter in the group in which the number of categories achieved was 2. The observed connectivity changes were lateralized to the right hemisphere. This finding suggests that pathological changes in the right cingulate white matter may cause, in part, disturbances in executive functions in PD. Funding: This work was supported by a grant (NN402457138) from the Polish Ministry of Science and Higher Education. Keywords: Neuropsychiatry, Parkinson’s disease Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Neuropsychiatric Applications Citation: Szatkowska I, Gawrys L, Pilacinski A, Bielecki M, Piatkowska-Janko E, Wolak T, Falkiewicz M, Andrysiak R, Friedman A and Krolicki L (2011). Neural bases of executive dysfunctions in parkinson’s disease: a diffusion tensor imaging study. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00113 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 17 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Iwona Szatkowska, Nencki Institute of Experimental Biology, Warsaw, Poland, i.szatkowska@nencki.gov.pl Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Iwona Szatkowska Ludwika Gawrys Artur Pilacinski Maciej Bielecki Ewa Piatkowska-Janko Tomasz Wolak Marcel Falkiewicz Renata Andrysiak Andrzej Friedman Leszek Krolicki Google Iwona Szatkowska Ludwika Gawrys Artur Pilacinski Maciej Bielecki Ewa Piatkowska-Janko Tomasz Wolak Marcel Falkiewicz Renata Andrysiak Andrzej Friedman Leszek Krolicki Google Scholar Iwona Szatkowska Ludwika Gawrys Artur Pilacinski Maciej Bielecki Ewa Piatkowska-Janko Tomasz Wolak Marcel Falkiewicz Renata Andrysiak Andrzej Friedman Leszek Krolicki PubMed Iwona Szatkowska Ludwika Gawrys Artur Pilacinski Maciej Bielecki Ewa Piatkowska-Janko Tomasz Wolak Marcel Falkiewicz Renata Andrysiak Andrzej Friedman Leszek Krolicki Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.