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PubMed2002

High-contrast images of semiconductor sites via one-photon optical beam-induced current imaging and confocal reflectance microscopy.

We demonstrate a computationally efficient procedure for determining only the semiconductor sites in a confocal reflectance image of an integrated circuit. It utilizes a one-photon optical beam-induced current (1P-OBIC) and confocal reflectance images that are generated from the same focused excitation beam. A 1P-OBIC image is a two-dimensional map of the currents induced by the beam as it is scanned across the circuit surface. A 1P-OBIC is produced by an illuminated semiconductor material if the excitation photon energy exceeds the bandgap. The 1P-OBIC image has no vertical resolution because the 1P-OBIC is linear with the excitation beam intensity. The exclusive high-contrast image of semiconductor sites is generated by the product of the 1P-OBIC image and the confocal image. High-contrast images of the metal sites are also obtained by the product of the complementary OBIC image and the same confocal image.

Journal Article↗
PubMed1987

Dyke award. Imaging of spinal CSF pulsation by 2DFT MR: significance during clinical imaging.

Understanding the MR appearance of spinal CSF is important in interpreting clinical spine images because the diagnosis of spinal pathology requires an accurate delineation of spinal CSF from spinal cord and thecal sac. During conventional 2DFT MR imaging of the spine, CSF pulsation caused two interdependent flow phenomena, signal loss and phase-shift images. Signal loss was observed as decreased signal intensity arising from pulsatile spinal CSF. Phase-shift images were observed as signal intensity arising from and morphologically identical to the spinal subarachnoid space but symmetrically displaced from it along the phase-encoding axis of MR images, either added to or subtracted from stationary signal intensity. These phenomena were common, occurring in most cervical and thoracic long-TR images. Both phenomena were less apparent in the lumbar region in most cases. CSF pulsation flow phenomena decreased CSF-spinal cord and CSF-thecal sac conspicuity, thereby obscuring normal and pathologic anatomy and, at times, simulating pathology. The areas of signal loss showed variable but characteristic patterns in the cervical and thoracic spine corresponding to regions of greatest flow. Signal loss in the axial plane was more pronounced when thin slices were used. Phase-shift images degraded overall image quality secondary to spatial mismapping of spinal CSF signal intensity. With the use of CSF gating, both signal loss and phase-shift images were eliminated. Understanding these features will be important in the accurate interpretation of MR spine images because analysis of CSF pulsation flow phenomena provides physiologic and pathologic information, and awareness of their existence avoids diagnostic confusion.

Adolescent↗
PubMed2001

Spiral computed tomographic imaging related to computerized ultrasonographic images of carotid plaque morphology and histology.

OBJECTIVE: Echolucency of carotid atherosclerotic plaques, as evaluated by computerized B-mode ultrasonographic images, has been associated with an increased incidence of brain infarcts on cerebral computed tomographic scans. We tested the hypotheses that characterization of carotid plaques on spiral computed tomographic images correlates with that on computerized B-mode ultrasonographic images and that spiral computed tomographic imaging predicts the histomorphometric plaque content. METHODS: The study included 38 patients with neurologic symptoms and at least 50% stenosis of the ipsilateral carotid artery. High-resolution B-mode ultrasonographic images and spiral computed tomographic images of carotid plaques were computer processed to yield a quantitative measure, the gray scale level of the plaque. RESULTS: The mean Hounsfield value for spiral computed tomographic images correlated with the gray scale median for B-mode ultrasonographic images (univariate linear regression analysis: r = 0.45; P = .01) and the histologic content of calcification in the plaque (r = 0.34; P = .04) but not with lipid, hemorrhage, or fibrous tissue in the plaque. CONCLUSIONS: Spiral computed tomographic imaging seems to correlate with B-mode ultrasonographic imaging for showing plaque characteristics. Spiral computed tomographic attenuation was also correlated with the amount of calcification noted on histologic examination but not with lipid and hemorrhage, the components thought to characterize vulnerable, rupture-prone plaques.

Carotid Arteries↗
PubMed2006

Contribution of tissue harmonic imaging and frequency compound imaging in interventional breast sonography.

OBJECTIVE: The purpose of this study was to retrospectively compare conventional imaging, frequency compound imaging (CI), and tissue harmonic imaging (THI) in interventional breast sonography. METHODS: Institutional Review Board approval and patient informed consent were not required. The authors reviewed 104 sonographically guided breast procedures in 83 patients. For each biopsy, 4 images obtained with conventional imaging, frequency CI at 10 and 14 MHz (CI10 and CI14), and THI were graded independently by 2 radiologists for lesion conspicuity, needle conspicuity, lesion and needle conspicuity, and overall image quality. Frequency CI at 10 MHz, CI14, and THI were compared with conventional imaging. Different clinical scenarios (fatty versus glandular background, fine needle versus core needle, and oblique versus horizontal needle direction) were evaluated. RESULTS: Statistical analysis showed that for overall image quality, CI10 was the best setting (odds ratios [OR], 3.67 and 7.48). For lesion conspicuity, CI14 (OR, 3.55) and THI (OR, 1.77) improved lesion visibility in a fatty background, whereas THI (OR, 0.26) was very limited in a glandular background. For needle conspicuity, no setting was better than conventional, whereas THI was the least valuable setting (OR, 0.011 and 0.049). For lesion and needle conspicuity, CI10 showed significantly better results than conventional for a dense background (P = .0268 and .4028; OR, 2.435 and 1.383) with 1 reviewer, whereas THI was the least valuable setting (OR, 0.014 and 0.042). CONCLUSIONS: Conventional imaging provided the best assessment of lesion and needle conspicuity. Frequency compounding is a useful setting for dense breast and for fine-needle aspiration. Tissue harmonic imaging has a role in the visualization of a lesion against a fatty background but is of limited value in needle visualization.

Adult↗
PubMed2004

Noninvasive imaging for monitoring of viable cancer cells using a dual-imaging reporter gene.

UNLABELLED: Molecular imaging methods have been used recently to investigate biologic events. To develop a molecular imaging method suitable for monitoring viable cancer cells, we made a dual-imaging reporter gene system and examined the correlation between cancer cell number and signals from 2 reporter genes, sodium iodide symporter (NIS) and luciferase. METHODS: NIS and luciferase genes were linked with the internal ribosomal entry site and transfected into SK-HEP1 cells to generate SK-HEP1-NL cells. (125)I uptake assays, luciferase assays, and scintigraphic and luminescence imaging were performed on SK-HEP1-NL cells. After treating with doxorubicin, cell counting, assays, and imaging were performed. SK-HEP1 and SK-HEP1-NL cells were inoculated subcutaneously into the flanks of nude mice. After incubation, scintigraphic and luminescence images were acquired and quantitated. RESULTS: The results of radioiodide uptake, luciferase assay, and scintigraphic and luminescence imaging in vitro correlated well with viable cell numbers. Upon increasing the concentration of doxorubicin, cell numbers decreased, and this correlated with a decrease in radioactivity and luminescence intensity. The radioactivity from in vivo scintigraphic images and the intensity from luminescence images were also found to be proportional to the tumor weight. CONCLUSION: The developed dual-reporter imaging method using NIS and the luciferase gene reflected viable cancer cell numbers and could detect changes in cell number after doxorubicin treatment.

Animals↗
PubMed1995

A comparative study of digital images versus 35-millimeter images.

Digital imaging is an alternative to 35-mm Kodachromes and may be a useful tool to the physician. The purpose of this study was to compare the quality of digital images to 35-mm images and then compare the two methods based on the ability to make the correct diagnosis. Dermatology patients were photographed with both a digital camera and a 35-mm camera. Images from 22 patients were compared and graded on four criteria (sharpness of image, contrast, depth of field, and trueness of color). Diagnoses were then made from 30 pairs of images of different patients. In all graded areas the 35-mm images scored significantly higher. The correct diagnosis was made in 69.6% of the digital images compared to 77.3% of the 35-mm images, a difference that was not statistically significant. One may conclude that digital images hold promise for present and future use in dermatology and other areas of medicine.

Dermatology↗
PubMed1996

Iodine-123-MIBG imaging of neuroblastoma: utility of SPECT and delayed imaging.

UNLABELLED: Possible incremental diagnostic benefits of SPECT and delayed planar imaging with [123I]MIBG in neuroblastoma have not yet been fully established. METHODS: Whole-body delayed planar [123I]MIBG imaging at 48 hr and SPECT imaging of the chest-abdomen or other suspected sites obtained at 24 hr were compared with routine planar imaging at 24 hr in 83 studies of 29 children with neuroblastoma. The sensitivity for each of the [123I]MIBG imaging methods was calculated on a study-by-study and on a lesion-by-lesion basis. RESULTS: Fifty-one planar imaging studies were performed in 20 patients with evidence of disease which was detected in 48 studies by 24-hr imaging (94.1% sensitivity) and in 44 studies by 48-hr imaging (86.3% sensitivity). On a lesion-by-lesion basis, sensitivity was 88.8% for the 24-hr scan, 86.7% for the 48-hr scan and 92.2% for a combination of the two (p = ns). Forty-three SPECT studies were performed in 20 patients with evidence of disease in the field of view of the SPECT camera. Disease was detected in 40 SPECT studies (93% sensitivity), in 38 planar scans at 24 hr (84.4% sensitivity) and in 37 planar scans at 48 hr (86.0% sensitivity). On a lesion-by-lesion basis, sensitivity was 83.6% for the 24-hr planar scan, 86.1% for the 48-hr planar scan, 88.2% for a combination of the two planar scans and 97.9% for SPECT (p < 0.001 compared with planar). The anatomic locations of tumors were clearer on SPECT in 15 studies. CONCLUSION: Delayed 48-hr planar scanning may occasionally depict more lesions than 24-hr imaging, but it may also miss lesions with rapid washout. SPECT imaging significantly increases the number of lesions detected and better defines anatomic location of tumors.

3-Iodobenzylguanidine↗
PubMed2000

T2-weighted MR imaging for focal hepatic lesion detection: supplementary value of breath-hold imaging with half-Fourier single-shot fast spin-echo and multishot spin-echo echoplanar sequences.

The purpose of our study was to evaluate the supplementary value of breath-hold fat-suppressed T2-weighted magnetic resonance (MR) imaging with half-Fourier single-shot fast spin-echo (SE) or multishot SE echoplanar (EP) sequences combined with respiratory-triggered fat-suppressed fast SE T2-weighted MR imaging for detection and characterization of focal hepatic lesions. MR images in 42 patients with 82 solid, malignant and 77 nonsolid, benign lesions were analyzed. Image review was conducted on a segment-by-segment basis; in all, 333 liver segments were reviewed separately for solid and nonsolid lesions by three independent radiologists. For solid lesions, observer performance with receiver-operating-characteristic (ROC) analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. For nonsolid lesions, observer performance with ROC analysis in one radiologist and specificity in another significantly improved after adding single-shot fast SE images. Combining breath-hold half-Fourier single-shot fast SE imaging with respiratory-triggered fast SE imaging may be recommended for improved detection and characterization of focal hepatic lesions. J. Magn. Reson. Imaging 2000;12:444-452.

Adipose Tissue↗
PubMedDate not supplied

Fast, interactive algorithm for segmentation of a series of related images: application to volumetric analysis of MR images of the heart.

Magnetic resonance (MR) cine images of the beating heart have excellent spatial and temporal resolution. Extracting the boundaries of the heart from MR images for volumetric measurements is of considerable interest; however, since the number of images involved is large, tracing the boundaries by hand is tedious and prohibitively time consuming. The authors have developed an interactive method of boundary detection that uses the correlation between the cardiac boundaries on temporally or spatially adjacent images to increase the speed of the process and reproducibility of the measurement. A simulated cine MR study of a phantom (total of 155 images) and cardiac cine studies of two patients (192 images each) were analyzed by two independent observers. Analysis of the phantom data was completed in 5.6 minutes (2.16 seconds per image) by observer 1 and 6.3 minutes (2.4 seconds per image) by observer 2. The percent measurement errors for 31 phantom volumes (30-120 mL) were 0.96% and 0.83% for observers 1 and 2, respectively. The observers analyzed the patient studies in 14-23 minutes (4.4-7.2 seconds per image), with interobserver variabilities of 5.8% and 3.7% for the two patients, respectively. The authors conclude that their flexible, semiautomatic, interactive algorithm allows rapid and reproducible detection of structural boundaries.

Algorithms↗
PubMed1996

MR imaging of articular cartilage in the ankle: comparison of available imaging sequences and methods of measurement in cadavers.

OBJECTIVE: To assess hyaline cartilage of cadaveric ankles using different magnetic resonance (MR) imaging techniques and various methods of measurement. DESIGN AND PATIENTS: Cartilage thicknesses of the talus and tibia were measured in ten cadaveric ankles by naked eye and by digitized image analysis from MR images of fat-suppressed T1-weighted gradient recalled (FS-SPGR), sequences and pulsed transfer saturation sequences with (FS-STS) and without fat-suppression (STS); these measurements were compared with those derived from direct inspection of cadaveric sections. The accuracy and precision errors were evaluated statistically for each imaging technique as well as measuring method. Contrast-to-noise ratios of cartilage versus joint fluid and marrow were compared for each of the imaging sequences. RESULTS: Statistically, measurements from FS-SPGR images were associated with the smallest estimation error. Precision error of measurements derived from digitized image analysis was found to be smaller than that derived from naked eye measurements. Cartilage thickness measurements in images from STS and FS-STS sequences revealed larger errors in both accuracy and precision. Inter-observer variance was larger in naked eye assessment of the cartilage. Contrast-to-noise ratio of cartilage versus joint fluid and marrow was higher with FS-SPGR than with FS-STS or STS sequences. CONCLUSION: Of the sequences and measurement techniques studied, the FS-SPGR sequence combined with the use of digitized image analysis provides the most accurate method for the assessment of ankle hyaline cartilage.

Aged↗
PubMed2006

Trends in oncological CT imaging: clinical application of multidetector-row CT and 3D-CT imaging.

Computed tomography (CT) plays an essential role in oncological imaging as the modality of screening for malignancies, mapping out the treatment strategy at staging, assessing response to the treatment, and following up patient outcome after the treatment. The advent of multidetector-row CT (MDCT) has brought about dramatic changes in clinical oncological imaging. The very superior temporal and spatial resolution of MDCT has transformed CT imaging from a transaxial cross-sectional technique into an isotropic volume-imaging technique. MDCT facilitates multiphasic contrast-enhanced study for a wide range of body scanning in a single examination, as well as providing flexibility of multidirectional reconstruction and high-quality three-dimensional imaging. With increases in the number of detector rows year by year, systems with 64-detector rows have become commercially available in 2006. The purpose of this article is to review the status of CT imaging in oncological imaging: (1) to outline the impact of MDCT, focusing on oncological imaging and (2) to review the clinical applications of oncological CT imaging with MDCT.

Humans↗
PubMed1996

Observer performance in the localization of tubes and catheters on digital chest images: the role of expertise and image enhancement.

RATIONALE AND OBJECTIVES: To determine whether observer performance in the localization of tubes and catheters on computed radiography (CR) chest images can be improved by using an automatic image-processing algorithm. METHODS: Comparisons were made of CR hard-copy, CR soft-copy, and CR enhanced soft-copy images obtained with an image-processing algorithm. The enhanced images used gray-level optimization and nonlinear unsharp masking to emphasize the edges of the devices. Chest radiologists (n = 4), general radiologists (n = 4), and interns (n = 6) read 45 images that contained endotracheal tubes, pulmonary artery catheters, and central venous catheters. RESULTS: Chest radiologists had the smallest mean interobserver localization variability (4 mm), followed by general radiologists (6 mm) and interns (8 mm). Localization variability was greatest for hard-copy images and least for enhanced soft-copy images. CONCLUSION: Use of an automatic imaging-processing algorithm reduced localization variability and enabled the medical interns to perform at approximately the same level as the chest radiologists.

Algorithms↗
PubMed1998

MR imaging of rabbit hip cartilage with a clinical imager and specifically designed surface coils.

RATIONALE AND OBJECTIVES: The authors' purpose was to develop a magnetic resonance (MR) imaging technique for examining the hip joint of a rabbit with a clinical MR imager. MATERIALS AND METHODS: Fourteen hips of 10 male New Zealand white rabbits were examined on a 1.5-T MR imager with a specially designed surface coil. Field of view was 3-8 cm, matrix was 256-512 x 192-256, section thickness was 0.9-2.0 mm, and spacing was 0.3-0.5 mm. The hips were sectioned and evaluated by means of light microscopy. Measurements of cartilage thickness from MR images were correlated with those from histologic specimens. RESULTS: The resolution obtainable with a 1.5-T imager was adequate for imaging articular cartilage when a débrided rabbit hip specimen was placed in the center of a 3.5-cm single-loop coil. Rabbit hip cartilage had a trilaminar appearance on MR images. The coefficient of correlation between cartilage-thickness measurements was .81. CONCLUSION: MR imaging of rabbit hip cartilage can be performed on 1.5-T clinical MR imaging unit. Limitations due to the field strength can be overcome with efficiently designed surface coils.

Acetabulum↗
PubMed2000

Suitability of the general-purpose graphic printer as an image output device for digital dental x-ray images.

OBJECTIVES: The purpose of this study was to evaluate the suitability of the general-purpose graphic printer as an image output device for digital dental x-ray images. METHODS: The image quality as obtained by a thermal printer and by a dye sublimation printer was investigated. A grid pattern image was used to check parallelism and verticality of lines in each hard copy. A step-wedge image was printed with each printer, and the optical density, gradient, and root mean square granularity were compared. Depiction ability was also compared by using test images, including small signals. RESULTS: All of the lines were parallel and vertical on hard copies of both printers. The dye sublimation printer showed better results on optical density, gradient, root mean square granularity, and depiction ability. CONCLUSION: The dye sublimation printer produces images of the depiction ability comparable to the cathode ray tube display and seems suitable as an image output device for digital dental x-ray images.

Coloring Agents↗
PubMed2001

[Automated image analysis of lateral roentgen images of the spine using anatomic models].

PURPOSE: Development of a software for fully automated image analysis of lateral lumbar spine X-rays. MATERIAL AND METHOD: Using the concept of active shape models, we developed a software that produces a form model of the lumbar spine from lateral lumbar spine radiographs and runs an automated image segmentation. This model is able to detect lumbar vertebrae automatically after the filtering of digitized X-ray images. The model was trained with 20 lateral lumbar spine radiographs with no pathological findings before we evaluated the software with 30 further X-ray images which were sorted by image quality ranging from one (best) to three (worst). There were 10 images for each quality. RESULTS: Image recognition strongly depended on image quality. In group one 52 and in group two 51 out of 60 vertebral bodies including the sacrum were recognized, but in group three only 18 vertebral bodies were properly identified. CONCLUSION: Fully automated and reliable recognition of vertebral bodies from lateral spine radiographs using the concept of active shape models is possible. The precision of this technique is limited by the superposition of different structures. Further improvements are necessary. Therefore standardized image quality and enlargement of the training data set are required.

Humans↗
PubMed2005

Large deformation three-dimensional image registration in image-guided radiation therapy.

In this paper, we present and validate a framework, based on deformable image registration, for automatic processing of serial three-dimensional CT images used in image-guided radiation therapy. A major assumption in deformable image registration has been that, if two images are being registered, every point of one image corresponds appropriately to some point in the other. For intra-treatment images of the prostate, however, this assumption is violated by the variable presence of bowel gas. The framework presented here explicitly extends previous deformable image registration algorithms to accommodate such regions in the image for which no correspondence exists. We show how to use our registration technique as a tool for organ segmentation, and present a statistical analysis of this segmentation method, validating it by comparison with multiple human raters. We also show how the deformable registration technique can be used to determine the dosimetric effect of a given plan in the presence of non-rigid tissue motion. In addition to dose accumulation, we describe a method for estimating the biological effects of tissue motion using a linear-quadratic model. This work is described in the context of a prostate treatment protocol, but it is of general applicability.

Algorithms↗
PubMed1999

Nonactive antenna compensation for fixed-array microwave imaging: Part II--Imaging results.

Model-based imaging techniques utilizing microwave signal illumination rely heavily on the ability to accurately represent the wave propagation with a suitable numerical model. To date, the highest quality images from our prototype system have been achieved utilizing a single transmitter/single receiver measurement system where both antennas are manually repositioned to facilitate multiple illuminations of the imaging region, thus requiring long data acquisition times. In an effort to develop a system that can acquire data in a real time manner, a 32-channel network has been fabricated with all ports capable of being electronically selected for either transmit or receive mode. The presence of a complete array of antenna elements at data collection time perturbs the field distributions being measured, which can subsequently degrade the image reconstruction due to increased data-model mismatch. Incorporating the nonactive antenna-compensation model from Part I of this paper into our hybrid element near field image reconstruction algorithm is shown to restore image quality when fixed antenna-array data acquisition is used. Improvements are most dramatic for inclusions located in near proximity to the antenna array itself, although cases of improvement in the recovery of centered heterogeneities are also illustrated. Increases in the frequency of illumination are found to warrant an increased need for nonactive antenna compensation. Quantitative measures of recovered inclusion shape and position reveal a systematic improvement in image reconstruction quality when the nonactive antenna-compensation model is employed. Improvements in electrical property value recovery of localized heterogeneities are also observed. Image reconstructions in freshly excised breast tissue illustrate the applicability of the approach when used with our two-dimensional microwave imaging system.

Algorithms↗
PubMed1998

Subarachnoid space disease: diagnosis with fluid-attenuated inversion-recovery MR imaging and comparison with gadolinium-enhanced spin-echo MR imaging--blinded reader study.

PURPOSE: To evaluate fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) imaging in a blinded reader study for the detection of proved subarachnoid space (SAS) disease. MATERIALS AND METHODS: FLAIR MR imaging was performed in 62 patients (21 with proved SAS or meningeal disease) and 41 control patients. A subset of 24 patients (eight patients with proved SAS disease and 16 control patients) also underwent gadolinium-enhanced T1-weighted MR imaging. FLAIR images were interpreted blindly and independently by two neuroradiologists. RESULTS: For SAS disease, the overall sensitivity, specificity, and accuracy of FLAIR for both readers were 85%, 93%, and 90%. In the 15 patients with inflammatory or neoplastic meningitis only (six patients with acute subarachnoid hemorrhage [SAH] excluded), the sensitivity, specificity, and accuracy of FLAIR for both readers were 82%, 93%, and 90%. All six acute SAH cases were interpreted as abnormal on FLAIR images by both readers. In the 24 patients who underwent both FLAIR and gadolinium-enhanced T1-weighted MR imaging, the sensitivity, specificity, and accuracy of FLAIR imaging were 86%, 91%, and 89%; the sensitivity, specificity, and accuracy of gadolinium-enhanced T1-weighted imaging were 43%, 88%, and 74%. CONCLUSION: FLAIR is highly sensitive and specific for the diagnosis of SAS disease. Unenhanced FLAIR is superior to gadolinium-enhanced T1-weighted MR imaging for the diagnosis of SAS disease. These data have important implications, because FLAIR is performed without the costs and inherent risks of intravenous contrast agents. FLAIR also appears to be highly sensitive but nonspecific for acute SAH.

Adolescent↗