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We developed a multimodality fluorescence and optical coherence tomography probe based on a double-clad fiber (DCF) combiner. The probe is composed of a DCF combiner, grin lens, and micromotor in the distal end. An integrated swept-source optical coherence tomography and fluorescence intensity imaging system was developed based on the combined probe for the early diagnoses of atherosclerosis. This system is capable of real-time data acquisition and processing as well as image display. For fluorescence imaging, the inflammation of atherosclerosis and necrotic core formed with the annexin V-conjugated Cy5.5 were imaged. Ex vivo imaging of New Zealand white rabbit arteries demonstrated the capability of the combined system.

Background: In the new generation of EYECUBE devices, the angiography image and the OCT are included in a 3D illustration as an integration. Other diagnostic procedures such as autofluorescence and ICG can also be correlated to the OCT. The aim was to precisely classify various two-dimensional findings in relation to each other., Method: The new generation of OCT devices enables imaging with a low incidence of motion artefacts with very good fundus image quality - and with that, permits a largely automatic classification. The feature enabling the integration of the EYECUBE was further developed with new software, so that not only the topographic image (red-free, autofluorescence) can be correlated to the Cirrus OCT, but also all other findings gathered within the same time frame can be correlated to each other. These were brightened and projected onto the cube surface in a defined interval. The imaging procedures can be selected in a menu toolbar. Topographic volumetry OCT images can be overlayed. The practical application of the new method was tested on patients with macular disorders., Results: By lightening up the results from various diagnostic procedures, it is possible of late to directly compare pathologies to each other and to the OCT results. In all patients (n = 45 eyes) with good single-image quality, the automated integration into the EYECUBE was possible (to a great extent). The application is not dependent on a certain type of device used in the procedures performed., Conclusions: The increasing level of precision in imaging procedures and the handling of large data volumes has led to the possibility of examining each macular diagnostics procedure from the comparative perspective: imaging (photo) with perfusion (FLA, ICG) and morphology (OCT). The exclusion of motion artefacts and the reliable scan position in the course of the imaging process increases the informative value of OCT., (© Georg Thieme Verlag KG Stuttgart · New York.)

Temporal filtering methods were applied to iodine signal-to-noise ratio (SNR) restoration in intravenous hybrid subtraction digital subtraction angiography (DSA). For equal detected exposure rates hybrid subtraction had approximately 35% of the SNR of temporal subtraction. When matched filtering was applied to a DSA run, the filtered result had approximately two times higher SNR than the peak contrast image in the run. Thus, when matched filtering techniques were applied to the hybrid image sequence, the resultant SNR increased to about 70% of that of temporal subtraction. With an additional factor-of-two increase in exposure rate for the hybrid run, SNR parity with temporal subtraction could be achieved. This compared with a factor-of-nine increase in exposure that would be required if no filtering were performed. Experimental hybrid matched filter results, generated with intravenous canine DSA studies, supported the predictions in SNR performance.

The rapid development of equipment for digital subtraction angiography (DSA) has created a new diagnostic imaging method, the limits of which have not been scientifically determined. Yet through aggressive marketing, the technique is already beginning to permeate radiologic practice. The radiologist requires technical understanding of the instrumentation for informed judgment on clinical applications. DSA depends on the mating of high-resolution image-intensifier and television technology with computerized information manipulation and storage. In this overview, the individual components of the system are analyzed, from the generator to the image intensifier to the television system to the associated computer. By examining the role of each component, the current limitations and the areas of possible future development of DSA can be understood. This provides a basis for dealing with current technology and for evaluating the rapid technological changes that will occur over the next few years.

Fifty-one arteriograms were obtained outside of the radiology department with portable digital subtraction angiographic equipment. Thirty-five studies were performed in the emergency room, 12 in the operating room, and four in the intensive care unit. There was a significant decrease in the time interval from arrival in the emergency room to arteriogram completion for examinations performed in the emergency room with portable equipment, compared with those performed in the radiology department. One of the 51 examinations yielded questionable results and was repeated with the conventional screen-film technique. Accurate angiographic diagnoses can be obtained by means of portable equipment in a variety of hospital locations.

We report the results and indications of 106 digital subtraction angiographies in 84 pediatric patients up to 16 years of age. 70 of the intravenous and all of the 21 intraarterial studies revealed diagnostic results and no further vascular study for the demonstration of the pathologic conditions was necessary.

A variation of temporal recursive filtering for intravenous and intra-arterial digital subtraction angiography (DSA) is described. It results in a dynamic tomographic DSA display that may improve intravenous DSA performance by removing the confusion introduced by vessel overlap and reducing the severity of motion artifacts. A conventional circular tomographic apparatus was modified by the addition of a 23-cm image intensifier-television chain and made to run continuously at one revolution each 1.5 seconds. The video output was processed by the recursive filter in a two-step process resulting in a dynamic tomographic display of arterial opacification. Theory and results of initial animal studies are presented.

Recent developments in digital subtraction angiographic imaging are discussed. The technical characteristics of several alternate subtraction methods are reviewed, including integrated remasking, matched filtering, recursive filtering, hybrid subtraction, and tomographic digital subtraction angiography (DSA). The properties that each exhibits are compared with conventional DSA imaging, and the major expected limitations and applications of each technique are discussed.

An inexpensive digital subtraction angiography (DSA) apparatus that can perform live subtraction, processed subtraction, and road mapping is described. The apparatus can be used in any standard x-ray room with fluoroscopic capability, with a simple connection to the existing TV chain. It is especially useful in therapeutic neuroangiography.

A new system for digital vascular subtraction imaging is presented. The image receptor consists of a rare-earth screen with light output optically focused onto the photocathode of a low-light-level image Isocon camera. This system represents a departure from the conventional use of the image intensifier for digital subtraction imaging. Our initial results suggest that this system could be competitive with traditional image intensifier systems and that it deserves clinical trial.

Initial clinical results using a digital fluoroscopic implementation of the combined time-energy ("hybrid") subtraction technique are described, with emphasis on carotid and renal imaging. Where patient motion artifacts are due to soft-tissue motion alone, hybrid subtraction can remove them. Due to the need for a finite separation time between high- and low-energy pairs, however, the present implementation of the hybrid technique is not completely immune to soft-tissue motion. The intrinsic signal-to-noise ratio of hybrid imaging is less than that of conventional temporal subtraction. However, since the low-energy temporal subtraction images are included in the hybrid data set, the diagnostic quality of the examination is not compromised.

One hundred and seventy specially selected visceral angiograms were carried out on 96 patients using I-A DSA and 100 mm technique. 85.2% of the I-A DSA and 91.7% of the 100 mm images were of good quality. I-A DSA produced comparable or better quality than the 100 mm technique in 66% during the arterial phase, in 79% during the parenchymatous phase and in 70% during the venous phase. The 100 mm technique produced better quality in a third of the cases during the arterial phase and in a quarter of the cases during the parenchymal and venous phases. The indications for the 100 mm technique are failure of I-A DSA or the need for high spatial resolution.

Digital subtraction angiography (DSA) has been widely accepted and applied. The concentration of iodine in the vessels of interest is low in intravenous DSA. The resultant images can be improved to some extent by increasing the radiation dose. Therefore DSA could become, and possibly could remain, a relatively high-dose procedure. The contributions to dose from the various components of the examination such as fluoroscopy, positioning, test exposures, and final acquisition runs are considered separately. Individual segments of a DSA examination are discussed to show how and where opportunities arise to reduce doses to the lowest levels consistent with satisfactory images.

DSA is a promising method for improving the results of cerebrovascular angiography. Experience suggests that VI-DSA will have a more limited application than was originally expected. It is a low-risk, cost-efficient technique for serial and postoperative studies and for screening outpatients who may have occlusive extracranial lesions that have not been detected by noninvasive tests; however, false-negative results may be obtained. AI-DSA provides far more accurate and reliable results than VI-DSA and has the potential for increasing the flexibility, efficiency, and safety of angiography, in comparison with conventional techniques.

The authors report the preliminary results obtained with a prototype of a digital subtraction unit in intravenous aortography. This new method in its actual state of development is not able to replace conventional arteriography. The new technique can be applied in selected clinical conditions where conventional arteriography is contraindicated or impossible. Further improvement of the spatial resolution of the digital image and reduction of the amount of contrast medium may extend clinical applications of this method which may be able to reduce substantially the cost and morbidity of angiography.

In subdiaphragmatic Hodgkin's disease the most common sites of involvement include the para-aortic region, in particular the celiac trunk, the splenic pedicle, and the spleen. In treatment planning, no imaging modalities (i.e. lymphography, CT, US) have so far been able to realize the need for direct imaging of any of these areas on a simulation film, necessary for individual beam shaping. With intravenous digital subtraction angiography (IV DSA) a new imaging method is available that allows direct imaging of these regions in a frontal view. The way and extent the splenic artery crosses the left kidney can exactly be delineated. By using a subtrascope (as common in angiography) the DSA can exactly be superimposed and documented on a simulation film. The DSA drawn onto the simulation film serves as a base for defining an individual target volume in the upper abdominal region (splenic pedicle etc.). The kidney can be shielded in a highly individualized way by individual beamshaping blocks. From December 1985 to December 1986, we treated 35 patients by using this technique for treatment planning. In 32 evaluable patients the imaging accuracy for all sites was judged as "excellent" in 74%, "reasonable" in 19%, and "poor" in 7%. The course of the splenic artery in relation to the left kidney revealed 78% within or above the upper third. By DSA assisted localization the target volume could be accurately defined in every case with shielding of the kidney as much as possible. Compared to nonindividualized standard definitions ("including L1" and "including upper third of the kidney") DSA assisted individual target volume definition was more precise: "including L1" overestimates in 63%, "including upper third" underestimates in 53%. Compared to the standard definition ("including L1") reduction of up to 25% kidney volume to be irradiated could be achieved in 63%. DSA could be performed on an outpatient basis. The median duration of DSA performance was 20 minutes; superimposing and drawing at the subtrascope took median 20 minutes. There were no severe side effects.

Intravenous digital subtraction angiography using Fuji computed radiography system (FCR-DSA) was used to evaluate 57 preoperative patients with clinical manifestations of peripheral vascular disease of lower extremity. With its high contrast resolution and good special resolution, image of FCR-DSA could offer optimal information of vascular abnormality in lower extremity distal to midfoot for the diagnosis and the choice of management.

We used Wiener spectral analysis in order to investigate the different noise sources and the effects of various parameters such as pixel size, image intensifier (II) field size, and exposure level on the noise in an II-TV digital system. The digital Wiener spectra in terms of relative x-ray intensity were determined directly from the digital noise data in terms of pixel values, by use of the characteristic curve of the imaging system. From averaged, subtracted, and/or combination images, the amount of structure mottle relative to the amount of quantum mottle was estimated. We found that a substantial amount of structure mottle was included in our II-TV digital subtraction angiography system, whereas the electronic noise of the TV system was quite small relative to the quantum and structure mottle. The effects of time jitter on the noise in single-frame images (consisting of multiple video frames) and in subtracted and averaged images were also investigated.