Three-dimensional Anatomical Images Research Articles

Neuroanatomical substrates of depression in dementia with Lewy bodies and Alzheimer's disease.

Dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) are often associated with depressive symptoms from the prodromal stage. The aim of the present study was to investigate the neuroanatomical correlates of depression in prodromal to mild DLB patients compared with AD patients. Eighty-three DLB patients, 37 AD patients, and 18 healthy volunteers were enrolled in this study. Depression was evaluated with the Mini International Neuropsychiatric Interview (MINI), French version 5.0.0. T1-weighted three-dimensional anatomical images were acquired for all participants. Regression and comparison analyses were conducted using a whole-brain voxel-based morphometry (VBM) approach on the grey matter volume (GMV). DLB patients presented a significantly higher mean MINI score than AD patients (p = 0.004), 30.1% of DLB patients had clinical depression, and 56.6% had a history of depression, while 0% of AD patients had clinical depression and 29.7% had a history of depression. VBM regression analyses revealed negative correlations between the MINI score and the GMV of right prefrontal regions in DLB patients (p < 0.001, uncorrected). Comparison analyses between DLB patients taking and those not taking an antidepressant mainly highlighted a decreased GMV in the bilateral middle/inferior temporal gyrus (p < 0.001, uncorrected) in treated DLB patients. In line with the literature, our behavioral analyses revealed higher depression scores in DLB patients than in AD patients. We also showed that depressive symptoms in DLB are associated with decreased GMV in right prefrontal regions. Treated DLB patients with long-standing depression would be more likely to experience GMV loss in the bilateral middle/inferior temporal cortex. These findings should be taken into account when managing DLB patients.

Dynamic Imaging of Blood Coagulation Within the Hematoma of Patients With Acute Hemorrhagic Stroke.

The dynamics of blood clot (combination of Hb [hemoglobin], fibrin, and a higher concentration of aggregated red blood cells) formation within the hematoma of an intracerebral hemorrhage is not well understood. A quantitative neuroimaging method of localized coagulated blood volume/distribution within the hematoma might improve clinical decision-making. The deoxyhemoglobin of aggregated red blood cells within extravasated blood exhibits a higher magnetic susceptibility due to unpaired heme iron electrons. We propose that coagulated blood, with higher aggregated red blood cell content, will exhibit (1) a higher positive susceptibility than noncoagulated blood and (2) increase in fibrin polymerization-restricted localized diffusion, which can be measured noninvasively using quantitative susceptibility mapping and diffusion tensor imaging. In this serial magnetic resonance imaging study, we enrolled 24 patients with acute intracerebral hemorrhage between October 2021 to May 2022 at a stroke center. Patients were 30 to 70 years of age and had a hematoma volume >15 cm3 and National Institutes of Health Stroke Scale score >1. The patients underwent imaging 3×: within 12 to 24 (T1), 36 to 48 (T2), and 60 to 72 (T3) hours of last seen well on a 3T magnetic resonance imaging system. Three-dimensional anatomic, multigradient echo and 2-dimensional diffusion tensor images were obtained. Hematoma and edema volumes were calculated, and the distribution of coagulation was measured by dynamic changes in the susceptibilities and fractional anisotropy within the hematoma. Using a coagulated blood phantom, we demonstrated a linear relationship between the percentage coagulation and susceptibility (R2=0.91) with a positive red blood cell stain of the clot. The quantitative susceptibility maps showed a significant increase in hematoma susceptibility (T1, 0.29±0.04 parts per millions; T2, 0.36±0.04 parts per millions; T3, 0.45±0.04 parts per millions; P<0.0001). A concomitant increase in fractional anisotropy was also observed with time (T1, 0.40±0.02; T2, 0.45±0.02; T3, 0.47±0.02; P<0.05). This quantitative neuroimaging study of coagulation within the hematoma has the potential to improve patient management, such as safe resumption of anticoagulants, the need for reversal agents, the administration of alteplase to resolve the clot, and the need for surgery.

Molecular Engineering of Self-Immolative Bioresponsive MR Probes.

Real-time detection of bio-event in whole animals provides essential information for understanding biological and therapeutic processes. Magnetic resonance (MR) imaging represents a non-invasive approach to generating three-dimensional anatomic images with high spatial-temporal resolution and unlimited depth penetration. We have developed several self-immolative enzyme-activatable agents that provide excellent in vivo contrast and function as gene expression reporters. Here, we describe a vast improvement in image contrast over our previous generations of these bioresponsive agents based on a new pyridyl-carbamate Gd(III) complex. The pyridyl-carbamate-based agent has a very low MR relaxivity in the "off-state" (r1 = 1.8 mM-1 s-1 at 1.41 T). However, upon enzymatic processing, it generates a significantly higher relaxivity with a Δr1 = 106% versus Δr1 ∼ 20% reported previously. Single X-ray crystal and nuclear magnetic relaxation dispersion analyses offer mechanistic insights regarding MR signal enhancement at the molecular scale. This work demonstrates a pyridyl-carbamate-based self-immolative molecular platform for the construction of enzymatic bio-responsive MR agents, which can be adapted to a wide range of other targets for exploring stimuli-responsive materials and biomedical applications.

The inauguration of iRADIOLOGY

The first X-ray image of a human hand was taken by Wilhelm C. Röntgen. This achievement marked the beginning of modern medical imaging: Information within living bodies could be noninvasively visualized for the first time, bringing together radiology and medical imaging. Since then, new knowledge and advancements in this field have been rapidly emerging, with no sign of ever reaching a stopping point. Supported by increasingly powerful computers, X-ray technologies such as computed tomography (CT) provide three-dimensional anatomical images with high resolution and great accuracy, making them the most important tools and gold standards in clinical diagnosis. Gamma rays and positron emissions generated by radionuclides represent other forms of radiation harnessed by clinical imaging, which have led to the development of Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET). These imaging modalities realize three-dimension functional and metabolic imaging noninvasively and are widely used in oncology as powerful diagnostic and research tools. Optical imaging (OI) involves photons within the visible spectrum and surrounding regions (ultraviolet and near infrared). These radiations carry much lower energy, offering several advantages such as their nonionizing character, ease of use, and high spatial and temporal resolutions. OI operating within the second near infrared region represents another attractive research hotspot in the field of medical imaging. Its ability to achieve deep tissue penetration, combined with low biological background signal, supports broad clinical application. Imaging modalities such as Magnetic Resonance Imaging (MRI) and Ultrasound (US) have undergone important developments in recent years and have been widely used in soft tissue imaging. They have contributed irreplaceable and valuable information for condition assessment and medical decision-making. Equipped with radioactive molecular probes, PET and SPECT are now progressing into a new era of medical imaging: molecular imaging. Unlike CT and related technologies that specialize in the presentation of anatomical information, molecular imaging can visualize biophysical activity in 3D at the molecular level with high resolution, greatly complementing traditional medical imaging. This methodology has played a significant role in many areas, such as clinical diagnosis, therapy monitoring, preclinical disease research, drug discovery, and drug development. Current research efforts are also being directed toward designing imaging probes for other medical imaging modalities, including CT, OI, MRI, and US. These technologies are being intensively investigated with the goal of broadening their use in molecular imaging, offering more imaging perspectives and dimensions. Molecular imaging is now one of the primary driving forces of current medical imaging research and is expected to advance the field in several key directions. With all these advancing technologies and modalities, medical imaging has become intimately involved in the process of clinical treatment and has become the third largest clinical discipline through its integration with many specialties. Intensive and active research is being conducted in this multidisciplinary field, creating tremendous demand for the communication of scientific findings, ideas, and opinions. iRADIOLOGY is an open access and peer-reviewed international journal that focuses on the publication of high-quality scientific works in the field of medical imaging and related multidisciplinary research, with particular attention to their development and application in both fundamental research and clinical practice for the achievement of precision medicine and health. iRADIOLOGY is the official journal of the Chinese Society of Molecular Imaging in Chinese Biophysical Society, aiming to promote the prosperity and development of molecular imaging research and application. The “i” of iRADIOLOGY stands for integration, innovation, insight, interdisciplinary, international, and intelligence. After decades of development, imaging diagnosis has progressed from relying solely on morphological changes to a comprehensive diagnostic system that integrates morphology, function, metabolism, and molecular changes. Recent developments in medical imaging show a trend toward cross-integration with multidisciplinary subjects, such as artificial intelligence, big data mining, pathology, genetics, pharmacy, chemistry, materials science, and bioengineering. This broad discipline involves outstanding efforts from researchers across the world. iRADIOLOGY will bring together all research areas mentioned above and will offer insights into both fundamental and clinical aspects of state-of-the-art medical imaging. The journal will serve as a platform for effective communication and presentation of rapidly emerging innovations in these disciplines. The support and contributions of research colleagues in medical imaging and related disciplines are indispensable and important for the future success of iRADIOLOGY. We sincerely welcome and deeply appreciate your support in any form. It is our wish that iRADIOLOGY promotes the development of medical imaging and, in so doing, benefit the cause of human health. Zhen Cheng: Conceptualization (lead); Writing – original draft (lead); Writing – review & editing (lead). None. The author declares no conflicts of interest. This article here has adhered to the relevant ethical guidelines. Data sharing is not applicable to this article as no new data were created or analyzed in this study.

The application of medical images in pharmacy

Introduction: The development of medical imaging methods offers nowadays essential tools not only for early diagnosis of diseases, as well as in supporting the therapy, in concrete with regard to planning and monitoring. The techniques considered include the areas of Radiology (CT, MRI and fMRI) and Nuclear Medicine (PET), with a view to understand, mainly, its relationship to the Pharmacy area. CT (Computer Tomography) allows the creation of high-definition bi and three-dimensional anatomical images as a result of submitting the human body to x-rays that cross the tissues in multiple directions. This technique can involve the use of pharmaceutical drugs as contrast agents. MRI (Magnetic Ressonance Imaging) subjects individuals to magnetic fields and radio frequency pulses and allows to get precise information about the anatomical structure. fMRI (functional Magnetic Ressonance Imaging) makes it possible to obtain information about brain function from the study of changes in blood flow and oxygenation. Nuclear Medicine techniques use radiopharmaceuticals (composed of a radionuclide and a drug) that are mainly used for medical diagnosis, but also, in some cases, for therapy. Using the technique of PET (Positron Emission Tomography) is possible, for example, to study the metabolism of glucose, associating the radionuclide Fluor to glucose, and thus assess the evolution of tumors. Materials and methods: A research paper work was conducted in order to identify and evaluate the relationship between the field of Pharmacy and the application and operation of various medical imaging techniques. Application examples are given and it is explored, in particular, the integration of information from different techniques (hybrid or multimodal imaging). Results: Duff and collaborators [1] show how reliable associations between drug-related activity modulations and drug efficacy can be identified using fMRI, in particular concerning analgesics (pain medication). Domingos Vieira and colleagues [2] show the hybrid PET-MRI system high potential in the diagnosis of neurodegenerative diseases, especially in case of Alzheimer’s disease in which are used radiopharmaceuticals marked with 18F, in order to identify the amyloid plaques formed and to evaluate the use of glucose by the brain. Sawicki and collaborators [3] show the high diagnostic potential of 18F-FDG PET-MRI system in patients with breast cancer, in comparison with 18F-FDG PET-CT system, MRI, and CT techniques. Discussion and conclusions: Imaging techniques are powerful with regard to early diagnosis of various diseases, as well as in the therapy assessment and have a close relationship with the area of the Pharmacy. The use of hybrid systems presents typically advantage over the use of separate techniques.

Multimodal Volumetric Retinal Imaging by Oblique Scanning Laser Ophthalmoscopy (oSLO) and Optical Coherence Tomography (OCT).

While fluorescence imaging is widely used in ophthalmology, a large field of view (FOV) three-dimensional (3D) fluorescence retinal image is still a big challenge with the state-of-the-art retinal imaging modalities because they would require z-stacking to compile a volumetric dataset. Newer optical coherence tomography (OCT) and OCT angiography (OCTA) systems overcome these restrictions to provide three-dimensional (3D) anatomical and vascular images, but the dye-free nature of OCT cannot visualize leakage indicative of vascular dysfunction. This protocol describes a novel oblique scanning laser ophthalmoscopy (oSLO) technique that provides 3D volumetric fluorescence retinal imaging. The setup of the imaging system generates the oblique scanning by a dove tail slider and aligns the final imaging system at an angle to detect fluorescent cross-sectional images. The system uses the laser scanning method, and therefore, allows an easy incorporation of OCT as a complementary volumetric structural imaging modality. In vivo imaging on rat retina is demonstrated here. Fluorescein solution is intravenously injected to produce volumetric fluorescein angiography (vFA).

A scalable method to improve gray matter segmentation at ultra high field MRI.

High-resolution (functional) magnetic resonance imaging (MRI) at ultra high magnetic fields (7 Tesla and above) enables researchers to study how anatomical and functional properties change within the cortical ribbon, along surfaces and across cortical depths. These studies require an accurate delineation of the gray matter ribbon, which often suffers from inclusion of blood vessels, dura mater and other non-brain tissue. Residual segmentation errors are commonly corrected by browsing the data slice-by-slice and manually changing labels. This task becomes increasingly laborious and prone to error at higher resolutions since both work and error scale with the number of voxels. Here we show that many mislabeled, non-brain voxels can be corrected more efficiently and semi-automatically by representing three-dimensional anatomical images using two-dimensional histograms. We propose both a uni-modal (based on first spatial derivative) and multi-modal (based on compositional data analysis) approach to this representation and quantify the benefits in 7 Tesla MRI data of nine volunteers. We present an openly accessible Python implementation of these approaches and demonstrate that editing cortical segmentations using two-dimensional histogram representations as an additional post-processing step aids existing algorithms and yields improved gray matter borders. By making our data and corresponding expert (ground truth) segmentations openly available, we facilitate future efforts to develop and test segmentation algorithms on this challenging type of data.

A reusable anatomically segmented digital mannequin for public health communication

The ongoing development of world wide web technologies has facilitated a change in health communication, which has now become bi-directional and encompasses people with diverse backgrounds. To enable an even greater role for medical illustrations, a data set, BodyParts3D, has been generated and its data set can be used by anyone to create and exchange customised three-dimensional (3D) anatomical images. BP3D comprises more than 3000 3D object files created by segmenting a digital mannequin in accordance with anatomical naming conventions. This paper describes the methodologies and features used to generate an anatomically correct male mannequin.

Abstract B02: Ultrasound evaluation of anti-angiogenic therapy on patient-derived renal cell carcinoma xenograft tumors in the chicken embryo model

Abstract Introduction: The avian embryo patient-derived xenograft (PDX) model's use as a platform for pre-clinical drug testing is a promising application. However, conventional methods of monitoring, such as tumor-take rates, light microscopy, and histology, either do not provide sufficient detail for in-depth therapy evaluation or are reserved for end-point analysis. Ultrasound monitoring permits non-destructive longitudinal evaluation of tumor growth, progression, and angiogenesis in the chorioallantoic membrane (CAM) xenograft ex ovo model. High-frequency ultrasound was selected for its low cost, lack of ionizing radiation, and high spatial and temporal resolutions. Methods: A subset of tumor initiating cells (RCC243) was isolated from a patient-derived parental renal carcinoma cell line (RCC22). Cells were grown to confluence, pelleted, and combined with an equal volume of Matrigel. On the ninth day of embryonic development (EDD-9), the CAM surface of 8 animals was pierced, and 10µL of the cell-Matrigel mix was deposited into the opening. Half of the embryos were treated every two days with 10µL of TAK-441, a Hedgehog inhibitor with hypothesized anti-angiogenic effects. Three-dimensional anatomical (B-mode) and contrast-enhanced images were acquired using a Vevo 2100 ultrasound system (VisualSonics Inc.) equipped with a 20 MHz linear array transducer. On EDD-18, tumor volumes were assessed using the B-mode images. The CAM vasculature was then cannulated with a glass capillary needle, and a 50µL solution of Vevo MicroMarker (VisualSonics Inc.) microbubble contrast agent (2 x 109 microbubbles/mL) was injected in a pulsatile manner. Tumor blood perfusion (blood volume, velocity, and flow) was then assessed using destruction-reperfusion contrast ultrasound. Image analysis was performed within manually segmented tumor volumes. Results: Hedgehog inhibition of RCC243 tumors via TAK-441 therapy produced a significant decrease in mean tumor volume (vehicle: 187.68 ± 69.55 mm3 vs. treatment: 78.94 ± 52.35 mm3; p &amp;lt; 0.05) and blood flow (vehicle: 645.7 ± 261.5 mm3/min vs. treatment: 190.8 ± 133.4 mm3/min; p &amp;lt; 0.05). There was a non-significant trend of reduced blood volume (vehicle: 97.0 ± 64.7 mm3 vs. treatment: 33.7 ± 23.8 mm3; p = 0.12), and flow velocity (vehicle: 6.34 ± 1.07 mm/s vs. treatment: 5.52 ± 1.18 mm/s; p = 0.34) in the treated tumors. Conclusions: This proof of principal study shows that tumors implanted in an ex ovo chick CAM model can successfully be imaged using high-frequency ultrasound and quantitative measures of tumor volume, blood volume, velocity and flow can be obtained. Responses to anti-angiogenic therapy can be successfully quantified. This approach to therapy evaluation is inexpensive and permits observation of tumor-induced angiogenesis over a 9 day timeframe. Citation Format: Matthew R. Lowerison, Chantalle J. Willie, Siddika Pardhan, Nicholas E. Power, Ann F. Chambers, Hon S. Leong, James C. Lacefield. Ultrasound evaluation of anti-angiogenic therapy on patient-derived renal cell carcinoma xenograft tumors in the chicken embryo model. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Angiogenesis and Vascular Normalization: Bench to Bedside to Biomarkers; Mar 5-8, 2015; Orlando, FL. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl):Abstract nr B02.

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.

Motor Homunculus: Passive Mapping in Healthy Volunteers by Using Functional MR Imaging—Initial Results

To determine the concurrence of activation in the primary motor cortex, induced by paradigms of active and passive movement of extremities, by using blood oxygen level-dependent functional magnetic resonance (MR) imaging. The HIPAA-compliant study was approved by the institutional review board, and written informed consent was obtained from the participating volunteers. Functional MR imaging data were collected from 11 healthy volunteers (four women, seven men; age range, 24-42 years) during active and passive movements of hand, elbow, shoulder, ankle, knee, and hip. These data were then mapped onto three-dimensional anatomic images. Volumes of activation were determined by using cross-correlation analysis at a coefficient threshold of 0.4 (P < .01). Regions of interest were drawn in pre- and postcentral gyri based on anatomic criteria. The mean number of activated voxels in the pre- and postcentral gyri induced by active and passive movements was compared by using Wilcoxon analysis. Concurrence ratios and proportional ratios of activation between active and passive movements were calculated for each somatotopic location. Primary motor cortex activation tended to increase with active compared with passive movements, although in the precentral gyrus, hand, elbow, and shoulder movements showed no statistically significant difference in mean number of activated voxels. In the postcentral gyrus, only the shoulder revealed a significant difference (P < .05). Concurrence ratios (activation volume overlap of two tasks/combined activation area of both tasks) ranged from 0.44 to 0.57. Proportional ratios (activation volume overlap of passive task with active task/total activation volume of passive task) ranged from 0.64 to 0.82. Passive movement paradigms may be an alternative to or complement to active movement tasks in patient populations.

THREE-DIMENSIONAL MICROSURGICAL AND TRACTOGRAPHIC ANATOMY OF THE WHITE MATTER OF THE HUMAN BRAIN

We sought to investigate the three-dimensional structure of the white matter of the brain by means of the fiber-dissection technique and diffusion-tensor magnetic resonance imaging to assess the usefulness of the combination of both techniques, compare their results, and review the potential functional role of fiber tracts. Fifteen formalin-fixed human hemispheres were dissected according to Klingler's fiber-dissection technique with the aid of 36 to 340 magnification. Three-dimensional anatomic images were created with the use of specific software. Two hundred patients with neurological symptoms and five healthy volunteers were studied with diffusion-tensor magnetic resonance imaging (3 T) and tractographic reconstruction. The most important association, projection, and commissural fasciculi were identified anatomically and radiologically. Analysis of their localization, configuration, and trajectory was enhanced by the combination of both techniques. Three-dimensional anatomic reconstructions provided a better perception of the spatial relationships among the white matter tracts. Tractographic reconstructions allowed for inspection of the relationships between the tracts as well as between the tracts and the intracerebral lesions. The combination of topographical anatomic studies of human fiber tracts and neuroanatomic research in experimental animals, with data from the clinicoradiological analysis of human white matter lesions and intraoperative subcortical stimulation, aided in establishing the potential functional role of the tracts. The fiber-dissection and diffusion-tensor magnetic resonance imaging techniques are reciprocally enriched not only in their application to the study of the complex intrinsic architecture of the brain, but also in their practical use for diagnosis and surgical planning.

Technique of semiautomatic surface reconstruction of the visible Korean human data using commercial software

This article describes the technique of semiautomatic surface reconstruction of anatomic structures using widely available commercial software. This technique would enable researchers to promptly and objectively perform surface reconstruction, creating three-dimensional anatomic images without any assistance from computer engineers. To develop the technique, we used data from the Visible Korean Human project, which produced digitalized photographic serial images of an entire cadaver. We selected 114 anatomic structures (skin [1], bones [32], knee joint structures [7], muscles [60], arteries [7], and nerves [7]) from the 976 anatomic images which were generated from the left lower limb of the cadaver. Using Adobe Photoshop, the selected anatomic structures in each serial image were outlined, creating a segmented image. The Photoshop files were then converted into Adobe Illustrator files to prepare isolated segmented images, so that the contours of the structure could be viewed independent of the surrounding anatomy. Using Alias Maya, these isolated segmented images were then stacked to construct a contour image. Gaps between the contour lines were filled with surfaces, and three-dimensional surface reconstruction could be visualized with Rhinoceros. Surface imperfections were then corrected to complete the three-dimensional images in Alias Maya. We believe that the three-dimensional anatomic images created by these methods will have widespread application in both medical education and research.

Role of magnetic resonance tractography in the preoperative planning and intraoperative assessment of patients with intra-axial brain tumours

This study was conducted to assess the possibility of identifying precise white matter tracts situated in proximity to intracranial tumours, to define the anatomical and topographical relations between the same white matter tracts and the tumour, to verify the possibility of integrating tractographic images in the context of a package of three-dimensional anatomical images to send to the neuronavigation system, to assess the impact of this information on surgical planning, and to analyse, both pre-and postoperatively, the patient's clinical conditions as an index of the functional integrity of the fibres themselves. Twenty-five patients underwent diffusion tensor study prior to neurosurgery. With the use of dedicated software, relative colour maps were obtained and the trajectories of the white matter tracts adjacent to the tumour were reconstructed in three dimensions. These were then processed for preoperative planning. Planning, which was performed with the neuronavigator, was based on analysis of the location of the course of the main white matter tracts adjacent to the lesion (pyramidal tract, optic radiation and arcuate fasciculus). Two neurosurgeons were asked whether the tractography images had modified the access and/or intraoperative approach to the tumour. All patients were clinically assessed both pre-and postoperatively 1 month after the procedure to define the presence of symptoms related to the involvement of the white matter tracts studied and therefore to assess the integrity of the fibres after the operation. In one patient, the tumour was situated away from all the tracts studied and did not compress them in any way. Overall, 40/75 tracts studied had no anatomical relation with the tumour, were not displaced by the tumour or could not be visualised in their entire course. Analysis of the remaining 35 white matter tracts led to an a priori change in the surgical approach for corticotomy in four patients (16%), with no disagreement between the two neurosurgeons and an impact on the extent of resection during surgery in 17 (68%), thus an overall impact on the surgical procedure in 80% of cases. Eight patients showed no symptoms related to the involvement of the white matter tracts studied. In the remaining 17 patients, the symptoms were related to involvement of the pyramidal tract, arcuate fasciculus or optic radiation. At 1-month follow-up, one previously asymptomatic patient reported a speech disorder (transcortical sensory dysphasia); in the remaining 24, symptoms remained unchanged, with a tendency to improvement in 14/17 with symptoms related to involvement of white matter tracts studied. Magnetic resonance (MR) tractography offers the neurosurgeon an anatomical panoramic view that can improve surgical planning for the resection of intracranial tumours. Despite the high incidence of cases in which the lesion is responsible for changes that hinder the reconstruction of white matter tracts, the technique can change the surgical approach for corticotomy, defines the extent of resection and leads to some change in the procedure in 80% of cases. The improvement of pre-existing symptoms and the absence of new symptoms in the postoperative phase, in our opinion, confirms the value of the technique.

Surgical Anatomy of Microneurosurgical Sulcal Key Points

The brain sulci constitute the main microanatomic delimiting landmarks and surgical corridors of modern microneurosurgery. Because of the frequent difficulty in intraoperatively localizing and visually identifying the brain sulci with assurance, the main purpose of this study was to establish cortical/sulcal key points of primary microneurosurgical importance to provide a sulcal anatomic framework for the placement of craniotomies and to facilitate the main sulci intraoperative identification. The study was performed through the evaluation of 32 formalin-fixed cerebral hemispheres of 16 adult cadavers, which had been removed from the skulls after the introduction of plastic catheters through properly positioned burr holes necessary for the evaluation of cranial-cerebral relationships. Three-dimensional anatomic and surgical images are displayed to illustrate the use of sulcal key points. The points studied were the anterior sylvian point, the inferior rolandic point, the intersection of the inferior frontal sulcus with the precentral sulcus, the intersection of the superior frontal sulcus with the precentral sulcus, the superior rolandic point, the intersection of the intraparietal sulcus with the postcentral sulcus, the superior point of the parieto-occipital sulcus, the euryon (the craniometric point that corresponds to the center of the parietal tuberosity), the posterior point of the superior temporal sulcus, and the opisthocranion, which corresponds to the most prominent point of the occipital bossa. These points presented regular neural and cranial-cerebral relationships and can be considered consistent microsurgical cortical key points. These sulcal and gyral key points can be particularly useful for initial intraoperative sulci identification and dissection. Together, they compose a framework that can help in the understanding of hemispheric lesion localization, in the placement of supratentorial craniotomies, as landmarks for the transsulcal approaches to periventricular and intraventricular lesions, and in orienting the anatomic removal of gyral sectors that contain infiltrative tumors.

Personal computer software evaluation in interactive generation of pig liver three-dimensional anatomical images

The efficiency of software for a personal computer in the interactive generation of three-dimensional (3D) images from computer tomography was studied in six pig livers after hepatic resection and catheterization of the hepatic and portal veins. After perfusion the livers were submitted to computed tomography angiography, volumetric measurement by water displacement, and production of an acrylic model of the veins by the injection and corrosion method, by which the lengths of the hepatic and portal veins were measured. From the angiogram, the software generated a 3D image that allowed measurement of the vein lengths. The identified branches of the hepatic and portal veins were correlated with the hepatic sectors and segments, respectively. The virtual measures from the 3D images were compared with the real measures. There were no significant differences between the topography and the vessel length. The mean difference between the volumes calculated from software and those measured by water displacement corresponded to 1.2%, and between the vessel lengths, 0.2%. In conclusion, the software for personal computer (named LIVER3D) is efficient, allowing interactive inspection of 3D images. All virtual measurements of liver vessel length and partial/total liver volume were similar to the actual ones.

Time-resolved three-dimensional phase-contrast MRI.

To demonstrate the feasibility of a four-dimensional phase contrast (PC) technique that permits spatial and temporal coverage of an entire three-dimensional volume, to quantitatively validate its accuracy against an established time resolved two-dimensional PC technique to explore advantages of the approach with regard to the four-dimensional nature of the data. Time-resolved, three-dimensional anatomical images were generated simultaneously with registered three-directional velocity vector fields. Improvements compared to prior methods include retrospectively gated and respiratory compensated image acquisition, interleaved flow encoding with freely selectable velocity encoding (venc) along each spatial direction, and flexible trade-off between temporal resolution and total acquisition time. The implementation was validated against established two-dimensional PC techniques using a well-defined phantom, and successfully applied in volunteer and patient examinations. Human studies were performed after contrast administration in order to compensate for loss of in-flow enhancement in the four-dimensional approach. Advantages of the four-dimensional approach include the complete spatial and temporal coverage of the cardiovascular region of interest and the ability to obtain high spatial resolution in all three dimensions with higher signal-to-noise ratio compared to two-dimensional methods at the same resolution. In addition, the four-dimensional nature of the data offers a variety of image processing options, such as magnitude and velocity multi-planar reformation, three-directional vector field plots, and velocity profiles mapped onto selected planes of interest.

Image acquisition: ultrasound, computed tomography, and magnetic resonance imaging.

As the transition toward total digital image acquisition continues, radiology is transcending the current standard of two-dimensional (2-D) cross-sectional anatomic imaging to more complex models. Among these are three-dimensional (3-D) anatomic images, constructed either from a synthesis of traditional 2-D data sets, or directly from volumetrically acquired data. However, current trends are moving beyond mere anatomic imaging to include physiological data once mainly obtained via nuclear medicine. Recent magnetic resonance pulse sequences, in addition to Doppler and harmonic ultrasound methods, are providing insight into blood flow, oxygenation, and metabolite concentrations non-invasively. Through image registration techniques, these data (even from differing modalities) are being assembled into 2-D and 3-D "fusion" images that promise to revolutionize diagnosis. Furthermore, with improvements in miniaturization, reliability, speed, built-in intelligence, and ease of use, these new developments are finding their way into use by nonspecialists. For instance, a new hand-held ultrasound unit will likely become a common tool among emergency medical teams, military medical teams, and in NASA's manned space program. Portable computed tomography (CT) scanners are already being used in the operating room. The increasing sophistication of imaging instruments will bring about a complementary increase in ease of use for both scanning and data interpretation, bringing diagnostic imaging and therapeutic capabilities closer to the patient, rather than the converse.

VR interaction techniques for medical imaging applications

Methods of virtual reality (VR) offer new ways of human–computer interaction. Medicine is predestined to benefit from this new technology in many ways. Virtual environments can support physicians in their work, alleviate communication between specialists from different fields or be established in educational and training applications. For the field of visualization and analysis of three-dimensional anatomical images (e.g. CT or MRI scans), an application is introduced which expedites recognition of spatial coherencies and the exploration and manipulation of the 3D data. To avoid long periods of learning and accustoming and to facilitate work in such an environment, a powerful human-oriented interface is required allowing interactions similar to the real world and utilization of our natural experiences. This paper shows the use of eye tracking parameters for a level-of-detail algorithm and the integration of a glove-based hand gesture recognition into the virtual environment as an essential component of the human–machine interface. Furthermore, virtual bronchoscopy and virtual angioscopy are presented as examples for the use of the virtual environment.

A method for co-registring three-dimensional multi-modality brain images

A method has been developed for co-registering three-dimensional multi-modality images of the human brain. The interactive program allows users to specify the interhemispheric fissure plane in three dimensions by identifying the endpoints of the centerline within transaxial slices. Translations and rotations within transaxial and coronal planes are determined to align the interhemispheric fissure planes of the two image sets to be co-registered. After reslicing the two partially co-registered image volumes, the intercommissural lines are detected by using three internal landmarks. A transformation including translation and rotation in the sagittal plane finally co-registers the two image sets in three-dimensional space. Single photon emission computed tomography (SPECT) images and magnetic resonance (MR) images have been used to validate the method for co-registering three-dimensional functional and anatomic brain images. This new co-registration method requires neither special head positioning procedures nor external fiducial markers, thereby making it appropriate for the routine clinical practice.