High-resolution Three-dimensional Magnetic Resonance Research Articles

Sensitivity of high-resolution three-dimensional magnetic resonance angiography and three-dimensional spoiled-gradient recalled imaging in the prediction of neurovascular compression in patients with hemifacial spasm

Hemifacial spasm is a clinical syndrome caused by vascular compression of the facial nerve in the cerebellopontine angle, which can be relieved by surgical intervention. Advances in medical imaging technology allow for direct visualization of the offending blood vessels in hemifacial spasm and similar conditions (such as trigeminal neuralgia). The utility of high resolution 3D MR angiography and 3D spoiled-gradient recalled (SPGR) imaging sequences for surgical decision-making in hemifacial spasm, as measured by sensitivity, specificity, and positive and negative predictive values, has not been previously determined. A retrospective review was undertaken of 23 patients with hemifacial spasm who underwent operations between January 2001 and December 2006 at Oregon Health & Science University. All patients underwent preoperative high-resolution 3D MR angiography and 3D SPGR imaging. The sensitivity of the SPGR imaging/MR angiography interpretation of neurovascular compression (NVC) by both a neurosurgeon and 2 neuroradiologists was determined in relation to the presence of actual NVC during surgery. All patients were found to have NVC at surgery. After review by a neurosurgeon and 2 neuroradiologists, imaging data from 19 of the 23 patients were evaluated. The neurosurgeon's interpretation had a sensitivity of 79% and a positive predictive value (PPV) of 100%. The first neuroradiologist's interpretation had a sensitivity of 21% with a PPV of 100%. Further interpretation by a blinded second neuroradiologist with expertise in MR imaging of hemifacial spasm and trigeminal neuralgia was conducted, and sensitivity was 59% and PPV was 100%. Specificity was not determined because there were no true negative cases. The negative predictive value was 0% for both the neurosurgeon's and neuroradiologists' evaluations. Although high-resolution 3D MR angiography and 3D SPGR imaging was helpful in providing information about the anatomical relationship of cranial nerve VII and surrounding blood vessels, the authors determined that in the case of hemifacial spasm these types of imaging did not influence preoperative surgical decisionmaking.

Generation of histo-anatomically representative models of the individual heart: tools and application.

This paper presents methods to build histo-anatomically detailed individualized cardiac models. The models are based on high-resolution three-dimensional anatomical and/or diffusion tensor magnetic resonance images, combined with serial histological sectioning data, and are used to investigate individualized cardiac function. The current state of the art is reviewed, and its limitations are discussed. We assess the challenges associated with the generation of histo-anatomically representative individualized in silico models of the heart. The entire processing pipeline including image acquisition, image processing, mesh generation, model set-up and execution of computer simulations, and the underlying methods are described. The multifaceted challenges associated with these goals are highlighted, suitable solutions are proposed, and an important application of developed high-resolution structure-function models in elucidating the effect of individual structural heterogeneity upon wavefront dynamics is demonstrated.

Identifying heritable brain phenotypes in an extended pedigree of vervet monkeys.

The area and volume of brain structural features, as assessed by high-resolution three-dimensional magnetic resonance imaging (MRI), are among the most heritable measures relating to the human CNS. We have conducted MRI scanning of all available monkeys >2 years of age (n = 357) from the extended multigenerational pedigree of the Vervet Research Colony (VRC). Using a combination of automated and manual segmentation we have quantified several correlated but distinct brain structural phenotypes. The estimated heritabilities (h(2)) for these measures in the VRC are higher than those reported previously for such features in humans or in other nonhuman primates: total brain volume (h(2) = 0.99, SE = 0.06), cerebral volume (h(2) = 0.98, SE = 0.06), cerebellar volume (h(2) = 0.86, SE = 0.09), hippocampal volume (h(2) = 0.95, SE = 0.07) and corpus callosum cross-sectional areas (h(2) = 0.87, SE = 0.07). These findings indicate that, in the controlled environment and with the inbreeding structure of the VRC, additive genetic factors account for almost all of the observed variance in brain structure, and suggest the potential of the VRC for genetic mapping of quantitative trait loci underlying such variance.

Structural and diffusional brain abnormality related to relatively low level alcohol consumption

Chronic excessive alcohol intake results in alcohol-related brain damage. Many previous reports have documented alcohol-related global or local brain shrinkage or diffusional abnormalities among alcoholics and heavy to moderate drinkers; however, the influence of relatively low levels of alcohol consumption on brain structural or diffusional abnormality is unclear. We investigated structural or diffusional abnormalities related to lifetime alcohol consumption (LAC) using voxel-based morphometry (VBM) among Japanese non-alcohol-dependent individuals (114 males, 97 females). High-resolution three-dimensional magnetic resonance images and diffusion tensor imaging were acquired in all subjects. The collected images were normalized, segmented, and smoothed using SPM 5. Gray matter volume (GMV) and white matter volume (WMV) were normalized for each total intracranial volume (TIV), and partial correlation coefficients were estimated between normalized GMV or WMV and lifetime alcohol consumption (LAC) adjusted for age. To investigate regional GMV or WMV abnormalities related to LAC, multiple regression analyses were performed among regional GMV or WMV and LAC, age, and TIV. To investigate subtle regional abnormalities, multiple regression analyses were performed among fractional anisotropy (FA) or mean diffusivity (MD), and LAC and age. No LAC-related global or regional GMV or WMV abnormality or LAC-related regional FA abnormality was found among male or female subjects. Significant LAC-related MD increase was found in the right amygdala among female subjects only. The current results suggest female brain vulnerability to alcohol, and a relation between subtle abnormality in the right amygdala and alcohol misuse.

Commentaries on Viewpoint: Use of mean airspace chord length to assess emphysema

to the editor: Although mean airspace chord length ( L m) lacks the elegance of some stereology methods and requires careful attention to technique ([4][1]), Mitzner ([3][2]) argues that L m has utility in studying experimental emphysema. Clearly, L m reflects the dimensions of alveoli but is not a

Migration of Neurotrophic Factors-Secreting Mesenchymal Stem Cells Toward a Quinolinic Acid Lesion as Viewed by Magnetic Resonance Imaging

Stem cell-based treatment is a promising frontier for neurodegenerative diseases. We propose a novel protocol for inducing the differentiation of rat mesenchymal stem cells (MSCs) toward neurotrophic factor (NTF)-secreting cells as a possible neuroprotective agent. One of the major caveats of stem cell transplantation is their fate post-transplantation. To test the viability of the cells, we tracked the transplanted cells in vivo by magnetic resonance imaging (MRI) scans and validated the results by histology. MSCs went through a two-step medium-based differentiation protocol, followed by in vitro characterization using immunocytochemistry and immunoblotting analysis of the cell media. We examined the migratory properties of the cells in the quinolinic acid (QA)-induced striatal lesion model for Huntington's disease. The induced cells were labeled and transplanted posterior to the lesion. Rats underwent serial MRI scans to detect cell migration in vivo. On the 19th day, animals were sacrificed, and their brains were removed for immunostaining. Rat MSCs postinduction exhibited both neuronal and astrocyte markers, as well as production and secretion of NTFs. High-resolution two-dimensional and three-dimensional magnetic resonance images revealed that the cells migrated along a distinct route toward the lesion. The in vivo MRI results were validated by the histological study, which demonstrated that phagocytosis had only partially occurred and that MRI could correctly depict the status of the migrating cells. The results show that these cells migrated toward a QA lesion and therefore survived for 19 days post-transplantation. This gives hope for future research harnessing these cells for treating neurodegenerative diseases. Disclosure of potential conflicts of interest is found at the end of this article.

A single-blinded pilot study assessing neurovascular contact by using high-resolution MR imaging in patients with trigeminal neuralgia

Objective To assess the feasibility and utility of high-resolution three-dimensional magnetic resonance angiography (3D MRA) and contrast-enhanced 3D spoiled gradient-recalled imaging (3D SPGRI) for the purpose of visualization of neurovascular contact in trigeminal neuralgia (TN) patients. Methods Forty-five patients (25 males, 20 females; age range, 23–82 years; and mean age, 55.67 ± 18.23 years) with unilateral typical TN and 36 control subjects (21 males, 15 females; age range, 25–85 years; mean age, 57.53 ± 19.25 years) underwent high-resolution 3D MRA and contrast-enhanced 3D SPGRI assessment. The images were reviewed by two experienced neuroradiologists who were blinded to the clinical details. The imaging results were compared with the operative findings in all the patients; additionally, the degree of neurovascular contact was compared between the two groups based on MR imaging. Results In 45 patients with unilateral typical TN, the use of 3D MRA in conjunction with the contrast-enhanced 3D SPGRI identified neurovascular contact in 40 of the 42 symptomatic nerves; the contact was verified surgically. Based on the surgical findings, the sensitivity and specificity of MR imaging were 95.20% and 100%, respectively. Based on MRI, the compressing vessel (artery, vein) was correctly identified in 32 of the 39 cases verified by microvascular decompression. There was good agreement ( K = 0.77; 95% confidence interval, 0.54–0.99) between the position (medial, lateral, superior, and inferior) of the compressing vessel relative to the trigeminal nerve as defined by MR imaging and the surgical findings. The rates of vascular contact with the trigeminal nerve as observed on MRI were 31.94%, 48.89%, and 88.9% in the control subjects, asymptomatic, and symptomatic side of patients, respectively. Conclusion The combined use of high-resolution 3D MRA and contrast-enhanced 3D SPGRI is an extremely sensitive and specific technique for demonstrating vascular contact with the trigeminal nerve in TN patients.

The value of high-resolution contrast-enhanced three-dimensional magnetic resonance angiography in the evaluation of hepatic arterial anatomy

目的 与DSA对照,评估高分辨对比增强三维MR血管成像(high-resolution 3D MRA)显示肝动脉解剖的价值.方法 回顾性分析26例肝肿瘤(24例为原发性肝癌,2例为转移性肝癌)患者腹部高分辨对比增强3D MRA和DSA检查的资料.对高分辨对比增强3D MRA和DSA的各段肝动脉显影质量行4级评分(1级记为1分,2级为2分,3级为3分,4级为4分),并对两者显影质量行weighted Kappa分析;分析评估肝动脉解剖或变异,以及病理情况,与DSA进行比较.结果 26例患者高分辨对比增强3D MRA和DSA对肝总动脉(显影评分平均为3.96、3.96)、胃十二指肠动脉(评分为3.85、3.88)的显示有很好的一致性(Kappa值分别为0.99、0.85),对肝右动脉(评分为3.92、3.96)、肝左动脉(评分为3.77、3.92)、胃左动脉(评分为3.73、3.85)、肝右前(评分为3.35、3.70)和右后动脉(评分为3.31、3.73)及第Ⅳ段动脉(评分为2.92、3.46)有较好的一致性(Kappa值分别为0.65、0.43、0.43、0.53、0.46、0.51),而对肝第Ⅱ(评分为2.15、3.35)、Ⅲ段动脉(评分为2.19、3.35)一致性差(Kappa值分别为0.18、0.21).以DSA为标准,高分辨对比增强3D MRA准确显示18例正常解剖和7例变异[显示的准确度为96.1%(25/26)],1例胃十二指肠动脉闭塞.结论 高分辨对比增强3D MRA是一项能准确评估肝动脉的检查技术,可以达到肝段动脉的显示水平。

High-Resolution Three-Dimensional Aortic Magnetic Resonance Angiography and Quantitative Vessel Wall Characterization of Different Atherosclerotic Stages in a Rabbit Model

Atherosclerosis results in a considerable medical and socioeconomic impact on society. We sought to evaluate novel magnetic resonance imaging (MRI) angiography and vessel wall sequences to visualize and quantify different morphologic stages of atherosclerosis in a Watanabe hereditary hyperlipidemic (WHHL) rabbit model. Aortic 3D steady-state free precession angiography and subrenal aortic 3D black-blood fast spin-echo vessel wall imaging pre- and post-Gadolinium (Gd) was performed in 14 WHHL rabbits (3 normal, 6 high-cholesterol diet, and 5 high-cholesterol diet plus endothelial denudation) on a commercial 1.5 T MR system. Angiographic lumen diameter, vessel wall thickness, signal-/contrast-to-noise analysis, total vessel area, lumen area, and vessel wall area were analyzed semiautomatically. Pre-Gd, both lumen and wall dimensions (total vessel area, lumen area, vessel wall area) of group 2 + 3 were significantly increased when compared with those of group 1 (all P < 0.01). Group 3 animals had significantly thicker vessel walls than groups 1 and 2 (P < 0.01), whereas angiographic lumen diameter was comparable among all groups. Post-Gd, only diseased animals of groups 2 + 3 showed a significant (>100%) signal-to-noise ratio and contrast-to-noise increase. A combination of novel 3D magnetic resonance angiography and high-resolution 3D vessel wall MRI enabled quantitative characterization of various atherosclerotic stages including positive arterial remodeling and Gd uptake in a WHHL rabbit model using a commercially available 1.5 T MRI system.

Cortical grey matter alterations in idiopathic restless legs syndrome: An optimized voxel‐based morphometry study

An impairment of central somatosensory processing is assumed in restless legs syndrome (RLS). Although functional neuroimaging in RLS gave evidence to the presence of widespread functional changes in various brain areas, structural changes at the cortical level were not reported to be RLS-associated to date. Here, an analysis of high-resolution three-dimensional magnetic resonance imaging (MRI) was performed in 63 patients with idiopathic RLS by use of optimized voxel-based morphometry, in order to investigate if cortical areas might be altered in volume at group level according to the phenomenology of RLS. The comparison of the RLS patients versus controls yielded significant regional decreases of gray matter volume at corrected P < 0.05 in the bihemispheric primary somatosensory cortex, which additionally extended into left-sided primary motor areas. All clusters correlated both with the severity of RLS symptoms and with disease duration. These results, for the first time, give in vivo evidence to structural neocortical gray matter alterations in RLS patients. The alterations in the sensorimotor cortices might add to the pathophysiological concepts of idiopathic RLS.

Knee cartilage thickness measurements using MRI: a 4½-month longitudinal study in the meniscectomized guinea pig model of OA

The aim of this study was to follow, over a 4(1/2)-month period, the medial tibia cartilage thickness on a meniscectomy (MNX) guinea pig osteoarthritis (OA) model and to compare with control animals, using three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI). MRI experimentations were performed in vivo at 7 T on guinea pig knee joints. 3D HR-MR images were acquired in 60 controls (SHAM) and 45 osteoarthritic animals (MNX) at four time-points (15, 45, 90 and 135 days) after surgery. Medial tibial cartilage thickness was measured from MRI images using in-house dedicated 3D software followed by a statistical analysis. At each time-point 15 SHAM and 15 MNX animals were sacrificed for histomorphometric assessments. No significant difference of mean cartilage thickness between the groups was found at early stage (D45) using MRI; however, significant differences were found between the groups at D90 (P<0.001) and D135 (P<0.001). Histomorphometry data confirmed the pathological status of the animals and was well correlated with MRI at D15 (r=0.79, P<0.01), D45 (r=0.67, P<0.01), and D135 (r=0.39, P<0.05) for SHAM, and at D45 (r=0.63, P<0.01), and D135 (r=0.81, P<0.01) for MNX. Medial tibial cartilage measurement based on HR-MR images enables the monitoring of longitudinal cartilage thickness changes. This technique showed significant differences between SHAM and MNX as from D90 after surgery. It could be used as a noninvasive and reproducible tool to monitor therapeutic response in this OA model.

High-Resolution Three-Dimensional Magnetic Resonance Imaging of Mouse Lung In Situ

This study establishes a method for high-resolution isotropic magnetic resonance (MR) imaging of mouse lungs using tracheal liquid-instillation to remove MR susceptibility artifacts. C57BL/6J mice were instilled sequentially with perfluorocarbon and phosphate-buffered saline to an airway pressure of 10, 20, or 30 cm H2O. Imaging was performed in a 7T MR scanner using a 2.5-cm Quadrature volume coil and a 3-dimensional (3D) FLASH imaging sequence. Liquid-instillation removed magnetic susceptibility artifacts and allowed lung structure to be viewed at an isotropic resolution of 78-90 microm. Instilled liquid and modeled lung volumes were well correlated (R = 0.92; P < 0.05) and differed by a constant tissue volume (220 +/- 92 microL). 3D image renderings allowed differences in structural dimensions (volumes and areas) to be accurately measured at each inflation pressure. These data demonstrate the efficacy of pulmonary liquid instillation for in situ high-resolution MR imaging of mouse lungs for accurate measurement of pulmonary airway, parenchymal, and vascular structures.

Iron Particles for Noninvasive Monitoring of Bone Marrow Stromal Cell Engraftment into, and Isolation of Viable Engrafted Donor Cells from, the Heart

Stem cells offer a promising approach to the treatment of myocardial infarction and prevention of heart failure. We have used iron labeling of bone marrow stromal cells (BMSCs) to noninvasively track cell location in the infarcted rat heart over 16 weeks using cine-magnetic resonance imaging (cine-MRI) and to isolate the BMSCs from the grafted hearts using the magnetic properties of the donor cells. BMSCs were isolated from rat bone marrow, characterized by flow cytometry, transduced with lentiviral vectors expressing green fluorescent protein (GFP), and labeled with iron particles. BMSCs were injected into the infarct periphery immediately following coronary artery ligation, and rat hearts were imaged at 1, 4, 10, and 16 weeks postinfarction. Signal voids caused by the iron particles in the BMSCs were detected in all rats at all time points. In mildly infarcted hearts, the volume of the signal void decreased over the 16 weeks, whereas the signal void volume did not decrease significantly in severely infarcted hearts. High-resolution three-dimensional magnetic resonance (MR) microscopy identified hypointense regions at the same position as in vivo. Donor cells containing iron particles and expressing GFP were identified in MR-targeted heart sections after magnetic cell separation from digested hearts. In conclusion, MRI can be used to track cells labeled with iron particles in damaged tissue for at least 16 weeks after injection and to guide tissue sectioning by accurately identifying regions of cell engraftment. The magnetic properties of the iron-labeled donor cells can be used for their isolation from host tissue to enable further characterization.

Effects of hormone therapy on brain morphology of healthy postmenopausal women

Estrogens are known to be protective in age-associated cognitive changes in humans and in neurodegeneration in animal models. The aim of this study was to evaluate the potential effects of estrogen therapy (ET) on human gray matter volume in vivo. Forty healthy postmenopausal women underwent three-dimensional high-resolution magnetic resonance imaging: 17 were never treated, 16 were currently receiving ET, and 7 had had ET in the past. Voxel-based morphometry (VBM) with SPM2 was used, according to an optimized protocol, to compare women under past and current ET to those never treated. Significance threshold was set at P = 0.01, corrected by false discovery rate. Voxel-based morphometry indicated that estrogen use was associated with greater gray matter volumes in the whole group of treated women, which included the cerebellum (cluster size, Z coordinates: 5,527; 5.15; -14 -54 -10), the amygdaloid-hippocampal complex (left: 19; 3.55; -22 -4 -18; right: 45; 3.61; 16 -6 -16), and extended to the frontal, temporal, parietal, and occipital neocortex. The comparison current ET versus past ET use showed that women who underwent treatment in the past had greater volumes of gray matter compared to women under current treatment. ET might slow down age-related gray matter loss in postmenopausal women. The structures that exhibited greater volume in association with ET included the cerebellar and cerebral cortices and, typically involved in Alzheimer's disease, the medial temporal structures and the temporoparietal junction.

Both Global Gray Matter Volume and Regional Gray Matter Volume Negatively Correlate with Lifetime Alcohol Intake in Non–Alcohol‐Dependent Japanese Men: A Volumetric Analysis and a Voxel‐Based Morphometry

Non-alcohol-dependent heavy drinkers, as well as alcohol-dependent individuals, show brain atrophy. The purpose of this study was to evaluate whether there are correlations between global and regional gray matter volumes and the lifetime alcohol intake using volumetric analysis and voxel-based morphometry (VBM) among Japanese non-alcohol-dependent male individuals. High-resolution three-dimensional magnetic resonance images were acquired from 405 Japanese non-alcohol-dependent male individuals. The collected images were normalized, segmented for volumetric analysis, and additionally smoothed for VBM. For volumetric analysis, the partial correlation coefficient was estimated between the gray matter ratio, which represents the percentage of gray matter volume in the intracranial volume, and the lifetime alcohol intake adjusted for the age of each subject. Multiple regression analysis was performed among regional gray matter volume, lifetime alcohol intake, and age using VBM. Volumetric analysis revealed that gray matter ratio showed a negative correlation with the lifetime alcohol intake adjusted for age (p=0.059, partial correlation coefficient=-0.091). The VBM revealed that the gray matter volumes of the bilateral middle frontal gyri showed a significant negative correlation with the lifetime alcohol intake adjusted for age and systolic blood pressure (left side, p=0.006, Z=4.77; right side, p=0.023, Z=4.45, and p=0.046, Z=4.27). Our study suggests that non-alcohol-dependent Japanese male individuals show that both global gray matter volume and regional gray matter volume have negative correlations with the lifetime alcohol intake. Our study may contribute to clarifying the mechanism underlying the brain structural changes because of alcohol influence in healthy non-alcohol-dependent individuals.

High-resolution Three-dimensional Magnetic Resonance Angiography and Three-dimensional Spoiled Gradient-recalled Imaging in the Evaluation of Neurovascular Compression in Patients with Trigeminal Neuralgia: A Double-blind Pilot Study

To assess the value of high-resolution three-dimensional (3D) time-of-flight (TOF) magnetic resonance (MR) angiography and gadolinium (Gad)-enhanced 3D spoiled gradient-recalled imaging in the visualization of neurovascular compression in patients with trigeminal neuralgia. Forty-eight patients with unilateral trigeminal neuralgia underwent high-resolution 3D TOF MR angiography. After administration of a contrast agent, a 3D spoiled gradient-recalled sequence (3D Gad) was run. Images were reviewed by a radiologist blinded to clinical details. All patients underwent microvascular decompression surgery. Microdissection of the trigeminal nerve and compressing vessels was videotaped during surgery and reviewed by surgeons uninvolved in patient care. Results from neuroradiological studies were then compared with findings on operative videotapes. MR angiography in combination with 3D Gad imaging identified surgically verified neurovascular contact in 42 of 46 (91%) symptomatic nerves. The offending vessel (artery, vein) was correctly identified in 31 of 41 cases (sensitivity, 76%; specificity, 75%). Neurovascular compression was observed in 71% of asymptomatic nerves with a trend toward greater compression severity on the symptomatic nerve (P < 0.09). Agreement between the direction of neurovascular contact defined by 3D TOF MR angiography and 3D Gad and findings at surgery was good (kappa = 0.78; 95% confidence interval, 0.61-0.94). Double-blind assessment of surgical and neuroradiological findings confirms that neurovascular compression can be visualized with good sensitivity in patients with trigeminal neuralgia by 3D TOF MR angiography in combination with Gad-enhanced 3D spoiled gradient-recalled sequences. Anatomic relationships defined by this method can be useful in predicting surgical findings.

Bench-to-bedside review: Critical illness-associated cognitive dysfunction – mechanisms, markers, and emerging therapeutics

Cognitive dysfunction is common in critically ill patients, not only during the acute illness but also long after its resolution. A large number of pathophysiologic mechanisms are thought to underlie critical illness-associated cognitive dysfunction, including neuro-transmitter abnormalities and occult diffuse brain injury. Markers that could be used to evaluate the influence of specific mechanisms in individual patients include serum anticholinergic activity, certain brain proteins, and tissue sodium concentration determination via high-resolution three-dimensional magnetic resonance imaging. Although recent therapeutic advances in this area are exciting, they are still too immature to influence patient care. Additional research is needed if we are to understand better the relative contributions of specific mechanisms to the development of critical illness-associated cognitive dysfunction and to determine whether these mechanisms might be amenable to treatment or prevention.

3D MRI‐based tumor delineation of ocular melanoma and its comparison with conventional techniques

The aim of this study is to (1) compare the delineation of the tumor volume for ocular melanoma on high-resolution three-dimensional (3D) T2-weighted fast spin echo magnetic resonance imaging (MRI) images with conventional techniques of A- and B-scan ultrasound, transcleral illumination, and placement of tantalum markers around tumor base and (2) to evaluate whether the surgically placed marker ring tumor delineation can be replaced by 3D MRI based tumor delineation. High-resolution 3D T2-weighted fast spin echo (3D FSE) MRI scans were obtained for 60 consecutive ocular melanoma patients using a 1.5 T MRI (GE Medical Systems, Milwaukee, WI), in a standard head coil. These patients were subsequently treated with proton beam therapy at the UC Davis Cyclotron, Davis, CA. The tumor was delineated by placement of tantalum rings (radio-opaque markers) around the tumor periphery as defined by pupillary transillumination during surgery. A point light source, placed against the sclera, was also used to confirm ring agreement with indirect ophthalmoscopy. When necessary, intraoperative ultrasound was also performed. The patients were planned using EYEPLAN software and the tumor volumes were obtained. For analysis, the tumors were divided into four categories based on tumor height and basal diameter. In order to assess the impact of high-resolution 3D T2 FSE MRI, the tumor volumes were outlined on the MRI scans by two independent observers and the tumor volumes calculated for each patient. Six (10%) of 60 patients had tumors, which were not visible on 3D MRI images. These six patients had tumors with tumor heights < or = 3 mm. A small intraobserver variation with a mean of (-0.22 +/- 4)% was seen in tumor volumes delineated by 3D T2 FSE MR images. The ratio of tumor volumes measured on MRI to EYEPLAN for the largest to the smallest tumor volumes varied between 0.993 and 1.02 for 54 patients. The tumor volumes measured directly on 3D T2 FSE MRI ranged from 4.03 to 0.075 cm3. with a mean of 0.87 +/- 0.84 cm3. The tumor shapes obtained from 3D T2 FSE MR images were comparable to the tumor shapes obtained using EYEPLAN software. The demonstration of intraocular tumor volumes with the high-resolution 3D fast spin echo T2 weighted MRI is excellent and provides additional information on tumor shape. We found a high degree of accuracy for tumor volumes with direct MRI volumetric measurements in uveal melanoma patients. In some patients with extra large tumors, the tumor base and shape was modified, because of the additional information obtained from 3D T2 FSE MR images.

Magnetic Resonance Imaging Study of Brain Asymmetries in Dyslexic Patients

Research studies suggest that the left hemisphere is involved in the pathophysiology of dyslexia. Thus far, the exact location and nature of the purported lesion(s) remain a matter of contention. The present study describes the distribution of structural abnormalities as related to brain symmetry in the brains of dyslexic individuals. High-resolution three-dimensional magnetic resonance images (MRIs) were analyzed in 16 dyslexic men and 14 controls matched for sex, age, educational level, and handedness. A computerized image analysis system was used to assess the volumetric deformations required to match each brain with its left-right mirror image. The results showed significant abnormalities in five left hemisphere structures involving the extrapyramidal and limbic systems: amygdala, hippocampus proper, parahippocampal gyrus, putamen, and globus pallidus. The left hemisphere is thought to play a major role in the temporal analysis of information. This stream of temporal analysis is of importance in motor movements. Reading might have evolved as an exaptation to motor movements requiring the sequential analysis of information.

MR Angiography of Tumor-related Vasculature: From the Clinic to the Micro-environment

Angiogenesis is a very important process for tumor growth and proliferation. Given its high temporal and spatial resolution, magnetic resonance (MR) imaging is well suited for use in the assessment of angiogenesis. MR angiography can be used clinically and experimentally for identification of tumor feeding and draining vessels, for tumor characterization, and for treatment planning. The morphologic structure of tumor vessels can be investigated in relation to tumor vessel permeability with use of specific contrast agents. To gain insight into tumor angiogenesis in vivo, the authors compared images obtained with digital photography, high-resolution MR angiography, and intravital microscopy through a dorsal skin-fold window in a rodent model. The close correlation between images obtained with these various modalities, with regard to the depiction of the developing tumor vasculature, indicates that noninvasive quantification of angiogenesis may be possible with MR imaging. Future directions in tumor imaging may include so-called four-dimensional MR angiography, in which high-resolution three-dimensional MR angiography is combined with dynamic contrast-enhanced MR imaging.