Three-dimensional digital ultrasound imaging system for surgical navigation

Validation and reproducibility of a high-resolution three-dimensional facial imaging system

We have introduced a three-dimensional (3-D) ultrasound imaging system for use in a combined ultrasound and near-infrared (NIR) imager for breast imaging. Compared with commercial ultrasound scanners which can only provide a single 2-D cross-section image at one scan, this 3-D system can provide 3-D co-registered ultrasound images for constraining regions of interest for 3-D NIR imaging reconstruction at one scan. The 3-D high-resolution ultrasound system consists of a state-of-the-art 1.75D ultrasound array of 1280 elements manufactured by Tetrad Inc. We have developed corresponding circuitry to drive the 1.75D array. The circuitry consists of 1280 parallel transmission channels, a 1280-to-40 multiplexer and 40 parallel receiving/data acquisition channels. A Texas Instrument DSP board has been embedded to speed up on-board data processing. We have tested the 3-D ultrasound imaging system with a 3-D ultrasound calibration phantom.

Quantitative evaluation of digital dental radiograph imaging systems

A digital x-ray imaging system was designed for small-animal studies. This system is a fiber-optics taper-coupled imaging system with two CCD arrays uniquely jointed. The x-ray source of the system has a small focal spot of 20 microm. This digital imaging system contains specially designed shelves to provide magnification levels, ranging from 1.5x to 5x. The system is characterized in terms of its properties of spatial resolution. An observer-based spatial resolution measurement was conducted with a line-pair target and a sector test pattern. The modulation transfer function of the system, with different magnifications, was studied by use of a 10-microm lead slit. The average resolutions at 50% and 5% modulations at 1x magnification were measured as 3.9 and 8.4 lp/mm, respectively, where lp indicates line pairs. With 5x magnification, the 50% and the 5% modulations provided 13.2- and 29.9-lp/mm, respectively, average spatial resolutions. The measurements showed consistency between the two individual CCD arrays; the difference in resolution between the two CCDs is less than 1%, even at high magnifications.

The purpose of this study was to compare nonmydriatic digitized images obtained using a digital imaging system (resolution of 640 x 480 pixels) with 35-mm slide images for detecting specific findings of age-related macular degeneration (AMD) and to evaluate its usefulness as a screening tool in detecting signs of AMD. Seventeen consecutive patients (33 eyes) underwent digital color imaging (with a nonmydriatic, 45-degree, fundus camera attached to a digital back) and standard 35-mm, 30-degree retinal color photography of the fundus: posterior pole, nasal retina, and temporal retina. The images were later reviewed for the presence or absence of specific retinal findings. The images were not compressed. Primary outcome measures included the presence or absence of drusen, hard exudate, choroidal neovascularization (CNV), subretinal hemorrhage, retinal pigment epithelial (RPE) changes, subretinal fibrosis, pigment epithelial detachment (PED), and subretinal fluid. Presence of drusen, with or without any one of the other findings, and presence of disciform scar or geographic atrophy were positive indications in screening for AMD. Agreement between image type was highest for PED (97%), CNV (91%), and subretinal fibrosis (91%); and lowest for RPE changes (63%). Sensitivity, specificity, positive predictive value, and negative predictive values were determined using the 35 mm-slide images as the reference for comparison. Sensitivity ranged from 40% (hard exudates) to 75% (subretinal hemorrhage). Specificity ranged from 88% (drusen) to 100% (hard exudate, CNV, RPE changes, PED). Positive predictive value ranged from 67% (subretinal hemorrhage) to 100% (hard exudate, CNV, RPE changes, PED). Negative predictive value ranged from 44% (drusen) to 97% (PED). For the purposes of screening for any evidence of AMD, the system was 70% sensitive. This digital fundus imaging system with 640 x 480 pixel resolution has low sensitivity and high specificity, as compared with 35-mm slide images, for detection of early AMD, but higher sensitivity for late findings (CNV, scar, atrophy) of AMD. Because of sensitivity for detecting any AMD coupled with the low sensitivity for detecting CNV, the system is not useful for evaluating AMD patients who require close follow-up and who are at risk for more severe visual loss.

Aim. To evaluate the clinical efficacy of microinvasive vitrectomy and three-dimensional digital imaging in patients with proliferative diabetic retinopathy.
 Methods. The clinical treatment results were studied in 62 patients (62 eyes) with proliferative diabetic retinopathy complicated by tractional retinal detachment who underwent vitreoretinal surgery with the use of microinvasive techniques and three-dimensional digital imaging. There were 38 (61%) women, 24 (39%) men, mean age 57±5.2 years. The duration of diabetes mellitus was 6 to 13 years (an average of 11.7 years). Of the 62 patients, 11 had insulin-dependent diabetes mellitus, and 51 had non-insulin-dependent diabetes.
 Results. Final anatomical result (the elimination of the zones of proliferation and adhesion of the retina) was reached in 59/62 (95.1%) of the eyes: in 54/62 (87%) eyes after the first intervention, in 8/62 eyes after additional surgical intervention. The maximum corrected visual acuity increased in 55/62 (88.7%) eyes from 0.01±0.12 to 0.22±0.11 (p <0.05); in 3/62 (4.8%) eyes remained the same; 4/62 (6.5%) eyes had visual impairment. Complications were diagnosed in 14 (22.6%) of the eyes: retinal tears (10), hemophthalmus (2), subchoroid hemorrhage (1), detachment of the choroid (1). Postoperative control of intraocular pressure demonstrated the following: 36 (58.1%) eyes had normal intraocular pressure (11–22 mm Hg), 20 (32.3%) — increased intraocular pressure (≥22 mm Hg), 6 (9.7%) — reduced intraocular pressure (≤10 mm Hg). In the postoperative period (up to 1 month after surgery) additional surgical interventions were performed on 8/62 (12.9%) eyes.
 Conclusion. In patients with proliferative diabetic retinopathy, the use of microinvasive vitreoretinal technologies and digital imaging system provide high anatomical (95.1% of patients) and functional results (88.7% of patients).

Digital photography has many advantages over the conventional method. At present commercially available digital ophthalmological imaging systems utilise only a fraction of the advantages of this technique and some of them have fundamental conceptional problems. Images of a fundus camera, a slit lamp and a scanning laser ophthalmoscope were digitised using digital and video cameras and/or frame grabber cards. Digital images and movies were recorded via a personal computer. The image recording software was developed using an imaging library and open source software. The recorded images and video sequences were processed with three different commercially available programme packages. The images were archived in a around-the-clock accessible database. Our digital imaging system is capable to record normal and high resolution slit lamp images, colour fundus images in normal resolution, Fluorescein angiography images in normal and high resolution, digital simultaneous ICG and Fluorescein videoangiograms (without compression) and high resolution macro images. Different functions, e.g., contrast enhancement are integrated in the image capture software. Most of the parameters of the image acquisition are individually adaptable. The digital image archive supports multiple image and video formats. Using standard software and hardware components an imaging system can be constructed featuring functions usually not available in commercial ones. Since the system is adaptable, recording of images with a wide variety of parameters, e.g., for measurements for scientific experiments, is possible.

Quantitation of thin-layer chromatography (TLC) using image analysis is attractive for its low cost and convenience. The image analysis is investigated by designing a digital imaging system with simple equipment, developing an image analysis software based on our algorithm, and validated the system in the TLC quantitative assay of cichoric acid present in Echinacea purpurea (L.) Moench. TLC used a polyamide thin-layer plate with chloroform-methanol formic acid-water (3:6:1:1) as the mobile phase and 3% (m/v) aqueous aluminum chloride solution as the visualization reagent. Images are acquired with a standard digital camera under a UV viewing lamp (365 nm) in a dark room. The three-dimensional gray scale digital image dataset (x, y, gray) is reduced to two-dimensional dataset (distance, accumulative gray) and then plotted as a curve. The area under the peak corresponding to the cichoric acid spot is integrated and used for quantitation. The whole method was validated by the assay tests of detection limit, calibration curve, repeatability, reproducibility, and recovery. The results showed that our digital imaging method and image analysis algorithm were applicable for the quantification of TLC. The whole method is convenient, efficient, and moderately accurate for the quantitative assay of cichoric acid present in Echinacea purpurea (L.) Moench.

Evaluating the use of exposure indicators in digital x-ray imaging system: Gauteng South Africa

The Japan Network for Research and Information on Medical Exposures (J-RIME) established the diagnostic reference level (DRL) and is advancing optimization of radiation protection. We believe that the difference in the imaging dose between facilities may be due to the fact that automatic exposure control (AEC) adjustment is not unified among manufacturers. The consistency of AEC is specified in JIS 4751-2-54, but it is not applicable to digital X-ray imaging systems because it is for optical density of analog X-ray imaging systems. This article evaluates the consistency of AEC in digital X-ray imaging systems. The AEC consistency was compared with the AEC-estimated dose from the air kerma (KAEC) using the phosphor-based imaging plate placed at the back of the AEC detector. We measured the AEC tube voltage and subject thickness characteristics (tracking) of four types of digital X-ray imaging systems at three facilities. In the test of tube voltage characteristics, the average KAEC values at all tube voltages were 2.37±0.04 µGy for A system, 7.30±1.44 µGy for B system, 3.53±0.13 µGy for C system, and 5.70±0.18 µGy for D system. The relative errors were +2.6 to -1.8% for A system, +25.3 to -22.6% for B system, +5.2 to -1.4% for C system, and +2.5 to -4.4% for D system. In the subject thickness characteristics test, the average KAEC values for all Al thicknesses were 2.34±0.02 µGy for A system, 5.95±0.23 µGy for B system, 4.25±1.12 µGy for C system, and 5.03±1.27 µGy for D system. The relative errors were +1.0 to -0.9% for A system, +4.1 to -5.0% for B system, +40.5 to -28.1% for C system, and +19.7 to -42.9% for D system.

Image contrast range for detection of enamel defects using a digital dental imaging system

Ethics review and clinical trials

The paper proposes the generalized technique of demodulation, which can be applied for capturing digital three-dimensional images in optical microscopes. This technique allows the calculation of the contrast of harmonic spatial modulation with any values of phase angles. The input data is a stack of digital images with harmonic spatial modulation. Three digital images with different phases of modulation captured in the same focus position are processed to get one data set about the contrast distribution. This data makes it possible to compose the three-dimensional images by the selection of the maximal values of the contrast in three-dimensional space. The paper contains the analytical solution of the system with three linear equations that helps to identify the principal parameters of harmonic spatial modulation, including its average value and contrast. As a result, the expression for contrast calculation is present in an analytical form. This expression is valid for any modulation phase angles that do not coincide. The paper contains MathCAD modeling, which illustrates the procedure of composing the three-dimensional images.
 The modeling confirms the correctness of described calculations and demonstrates the built of the three-dimensional surface image as a composition of the contrast distribution map and the corresponded height map. The advantage of the proposed technique is the possibility to apply the economical units for the formation of a harmonious spatial modulation. These units can be installed on most optical microscopes with digital cameras and motorized focusing drives without purchasing expensive commercial software. It significantly reduces the price of transforming these optical microscopes into instruments for capturing digital three-dimensional images.

Due to recent technical advancements of three-dimensional ultrasound imaging systems, applications of this imaging modality have been expanding from the fetal imaging to cardiac- and abdominal-diagnosis. Among all internal organs, diagnosing the kidney has a paramount importance for rapid bedside treatment of trauma and kidney stone patients using ultrasound images. Although three-dimensional ultrasound provides higher level of structural information of kidneys, manual kidney diagnosis using three-dimensional ultrasound images requires a highly trained medical staff, due to the extensive visual complexity which three-dimensional images contain. Therefore, computer aided automated kidney diagnosis becomes very essential. Due to the challenging problems of ultrasound images, such as speckle noise and inhomogeneous intensity profile, kidney segmentation in three-dimensional ultrasound images has not been sufficiently investigated by researchers. In this paper, we first propose a new automated kidney detection approach using three-dimensional Morison's pouch ultrasound images. Then, we proposed a shape-based method to segment the detected kidneys. A preprocessing step is utilized to overcome the ultrasound challenges. Based on a set of 14 ultrasound volumes, we have evaluated the detection rate of our proposed kidney detection approach which is 92.86%. For kidney segmentation, we compared our proposed method with an existing approach, and the performed statistical analysis strongly validates the superiority of our proposed method with p = 0.000032.

The laser three-dimensional imaging system has the advantages of rich information acquisition and fewer working conditions, which is a hot spot in the research of imaging methods. Pulse ranging laser 3D imaging obtains the relative distance between the imaging system and the target through the photon flight time. Although the distance resolution is usually on the order of centimeters, the working distance range is large, which can meet the working distance range and accuracy of laser 3D imaging at the same time. Demand. The three-dimensional imaging of array detectors such as APD array can significantly improve the three-dimensional imaging performance of the system, but the detector is limited by the area of the photosensitive area, and the energy utilization efficiency is still low. This article combines the requirements of the receiving optical system in the APD array three-dimensional imaging system to improve the energy transmission efficiency. First, it outlines the principle and basic composition of the microlens array to improve the energy transmission efficiency, and then briefly describes the microlens distribution size and focal length. The design constraints of the microlens. Finally, for the two cases of whether the microlens array is used or not, the difference in the efficiency of the receiving optical system is compared and analyzed. The analysis results can provide a certain reference for the design of APD array three-dimensional imaging.