Three-dimensional imaging.
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Bone and Bones↗
Biomedical subjects
D N Levin
Publications and source records attributed to D N Levin.
Analysis of PET images with the use of anatomic information from CT and MR images.
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Brain↗
Three-dimensional magnetic resonance images of the brain: application to neurosurgical planning.
Data from single 10-minute magnetic resonance scans were used to create three-dimensional (3-D) views of the surfaces of the brain and skin of 12 patients. In each case, these views were used to make a preoperative assessment of the relationship of lesions to brain surface structures associated with movement, sensation, hearing, and speech. Interactive software was written so that the user could "slice" through the 3-D computer model and inspect cross-sectional images at any level. A surgery simulation program was written so that surgeons were able to "rehearse" craniotomies on 3-D computer models before performing the actual operations. In each case, the qualitative accuracy of the 3-D views was confirmed by intraoperative inspection of the brain surface and by intraoperative electrophysiological mapping, when available.
Adolescent↗
Image correlation in oncology.
Image correlation techniques can provide objective spatial registration between multimodality data sets acquired during the planning and follow-up phases of radiation therapy. Correlation of pre-CT/MRI with follow-up CT/MRI and 3D dose matrices may provide insights into normal tissue tolerance. Correlation of SPECT and planar scintigraphs with anatomical maps derived from CT/MRI may be useful in the precise localization of disease and in the evaluation of new modalities, such as radiolabeled monoclonal antibodies, in the diagnosis and treatment of cancer. Correlation of PET and MRI may lead to a more precise understanding of structure-function relationships of the brain. The development and refinement of multimodality image-correlation techniques is a logical step in the evolving role of imaging in radiation therapy.
Brain Neoplasms↗
Surface of the brain: three-dimensional MR images created with volume rendering.
Image processing and volume rendering have been applied to magnetic resonance (MR) images to produce three-dimensional views of the surface of the brain. Four healthy volunteers and 17 patients with a variety of disorders underwent MR imaging of the head, and these images were processed and subjected to volume rendering. The resulting three-dimensional views depict abnormalities of the brain surface, as well as important landmarks of normal brain surface anatomy such as precentral, postcentral, superior temporal, and inferior frontal gyri, which are difficult to identify on cross-sectional images.
Adult↗
The brain: integrated three-dimensional display of MR and PET images.
Three patients with intractable epilepsy, two with brain tumors, and one with encephalitis were imaged with magnetic resonance (MR) and positron emission tomography (PET). MR data were used to construct a three-dimensional (3D) computer model of the brain surface depicting the precentral (movement), postcentral (sensation), left inferior frontal (speech), and left superior temporal (hearing) gyri. PET-derived measurements of average surface metabolism were encoded as colors and mapped onto the 3D model by means of a retrospective technique for registering the two scans. The integrated 3D model depicted the location of PET-detected metabolic abnormalities with respect to the gyral anatomy visualized with MR. In each case, the predicted relationships were confirmed intraoperatively by means of inspection of the brain and electroencephalography. Multimodality 3D displays are likely to be particularly valuable for interpreting PET studies of epileptic patients and others with normal MR anatomy.
Brain↗
SLIM: spectral localization by imaging.
Nonspectroscopic magnetic resonance (MR) imaging often shows that a slice is composed of several compartments, each of which can be assumed to have a spatially homogeneous magnetic resonance spectrum, e.g., a limb composed of fat, muscle, bone marrow, and tumor. We show how to use structural information from such a nonspectroscopic image in order to increase the efficiency of subsequent localized spectroscopic measurements. Specifically, knowledge of the boundaries of N compartments makes it possible to reconstruct compartmental spectra from spectroscopic signals from an entire cross section with N or more different degrees of phase encoding. Experimental studies of a two-compartment phantom show that this method (SLIM) can be used to derive regional hydrogen spectra of a single slice from signals with as few as 2 phase-encoding steps, although Fourier transform chemical-shift imaging requires 64 steps to achieve a result of comparable accuracy. SLIM required only 16 phase-encoding steps to obtain accurate regional single slice spectra in a human limb with three compartments. Spectra of similar quality, obtained by Fourier transform chemical-shift imaging, required 256 to 1024 steps.
Humans↗
Retrospective geometric correlation of MR, CT, and PET images.
Magnetic resonance imaging, computed tomographic, and positron emission tomographic studies of the brain provide complementary information, and many patients undergo more than one of these studies during the course of their diagnostic workup and treatment. A new technique for quantitative geometric correlation of such studies makes it possible to create integrated multimodality images by mapping features from one image onto an image obtained with another modality. The coordinate transformation between any pair of images is found by a semiautomatic algorithm for matching models of the patient's external surface as depicted in the two data sets. The resultant hybrid images, which combine complementary features of different studies, are often more useful for diagnosis and treatment planning than are the original single-modality images. The algorithm can also be used for spatial registration of baseline studies with follow-up images created with the same modality, which allows tracking of a lesion to detect subtle interval changes in size and shape. This technique can be applied to images acquired in routine clinical practice, since it is completely retrospective and does not necessitate special positioning or landmarking of the patient.
Adolescent↗
MR imaging of inferior vena caval filters: safety and artifacts.
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Filtration↗
Public attitudes toward cancer pain.
This study examined public attitudes toward pain associated with cancer and its treatment. A variety of issues were assessed, including the extent to which pain is associated with cancer, fear of pain as a factor in the decision to delay seeking treatment, and concerns about the use of narcotic analgesics for pain control. A statewide sample of 496 adult Wisconsin residents completed a telephone interview. It was found that cancer was perceived as an extremely painful disease relative to other medical conditions. Eighteen percent of the respondents reported that they might be reluctant to seek medical attention due to fear of pain. Concerns about disease- and treatment-related pain were rated as significant psychosocial concerns. There were multiple concerns expressed about the consequences of using narcotic analgesics for pain control. Implications for public education and patient management are discussed.
Analgesics, Opioid↗
Visualization of MR angiographic data with segmentation and volume-rendering techniques.
Novel image processing and computer graphics techniques were developed to create three-dimensional (3D) models of vasculature from magnetic resonance (MR) angiographic images of the head or neck. Region growing was used to produce a mask that isolated the vascular signal in the MR angiographic data. The masked images were subjected to gradient-shaded volume rendering to create 3D views of the vasculature. The computer-derived model of intracranial vasculature was then merged with a 3D model of brain parenchyma derived from a set of MR images. The combined display of vascular and gyral anatomy may be useful for neurosurgical planning.
Brain↗
MR imaging with spatially variable resolution.
In some situations it may be advantageous to produce "locally focused" magnetic resonance images that have nonuniform spatial resolution matching the expected local rate of spatial variation in the object. Because such an image has fewer pixels than a conventional image with uniformly high resolution, it can be reconstructed from fewer signals, acquired in less time. This can be done by using a highly convergent representation of the image as a sum of orthonormal functions with slow (fast) spatial variation in relatively homogeneous (heterogeneous) parts of the object. Since this series is shorter than a conventional truncated Fourier series, its terms can be calculated from a subset of the usual array of phase-encoded signals. The optimal choice of these phase encodings, which are usually scattered nonuniformly in k space, results in minimization of noise in the reconstructed image. The technique is illustrated by applying it to simulated data and to data from images of phantoms.
Computer Simulation↗
Retrospective fusion of radiographic and MR data for localization of subdural electrodes.
Prior to epilepsy surgery, subdural electrodes are often implanted and monitored for a few days to identify the focus of abnormal electrical activity. During the implantation and subsequent brain resection, there may be uncertainty about the exact location of the electrodes with respect to features of brain anatomy such as specific gyral convolutions or lesions. In experiments with a phantom and patients, implanted electrodes were imaged with multiplanar skull radiographs (or CT scans). After retrospective registration with preimplantation MR data, the electrodes were mapped from these studies onto an MR-derived three-dimensional brain model. The resulting multimodality displays showed the relationship of the electrodes to brain anatomy. In one patient the position of each electrode with respect to a metabolic lesion was also displayed by mapping preimplantation PET data onto the same brain model. This new display of electrode positions may strengthen the interpretation of subdural electrical recordings and thereby reduce uncertainty in planning the resection of epileptic tissue.
Adult↗