Comparison of cephalometric analysis using a non-radiographic sonic digitizer (DigiGraph Workstation) with conventional radiography.
(9/3731)
Cephalometric analysis conventionally requires radiographic exposure which may not be compatible with the growing concern over radiation hazards. Recently, the Dolphin Workstation Imaging System introduced to the dental profession a non-radiographic system, called the DigiGraph Workstation which may be an alternative to cephalometric radiography. The aims of this study were to compare the validity and reproducibility of cephalometric measurements obtained from the DigiGraph Workstation with conventional cephalometric radiographs. The sample consisted of 30 human dry skulls. Two replicated sets of lateral cephalograms were obtained with steel ball markers placed at the majority of the cephalometric landmarks. Duplicate tracings prepared from each radiograph were digitized to obtain cephalometric measurements using the computer software, Dentofacial Planner. For the DigiGraph Workstation, double sonic digitizations were repeated twice for each skull, on two occasions. Fifteen angular and one linear measurements were obtained from both methods and these findings compared using ANOVA, paired t-tests and F-tests. All, except one, cephalometric measurement showed significant differences between the two methods (P < 0.0001). The DigiGraph Workstation consistently produced higher values in 11 measurements (mean differences +0.5 to +15.7 degrees or mm) and lower values in four measurements (mean differences -0.2 to -3.5 degrees). The standard deviations of the differences between readings of both methods were large (0.4-5.8 degrees or mm). The reproducibility of the DigiGraph Workstation measurements was lower than that of the radiographic measurements. The method error of the DigiGraph Workstation ranged from 7 to 70 per cent, while that of radiographic tracings was less than 2 per cent. It was concluded that measurements obtained with the DigiGraph Workstation should be interpreted with caution. (+info)
Ultrasonic imaging of the electroacoustic effect in macromolecular gels.
(10/3731)
The electroacoustic effect occurs in electrolytes and colloidal suspensions. It describes the phenomenon in which a voltage applied to the sample produces an acoustic signal or vice versa. The basic mechanism is that charged particles in the sample have various mobilities due to different masses and viscosities. Under an external voltage they respond differently to the electrical force. This results in an overall acoustic vibration. The electroacoustic effect has been the basis for many measurement tools of solutions and other materials. In this note a method to image macromolecular gel samples using the electroacoustic effect at ultrasound frequencies is presented. Radiofrequency electrical excitation produces ultrasonic signal due to spatial changes in the electroacoustic some amplitude of the sample, which is used to construct an image similar to ultrasonography. This method is demonstrated in agar gel and egg-white protein phantoms. The image contrast mechanism is also discussed. (+info)
Image-guided central venous catheters for apheresis.
(11/3731)
Apheresis is an increasingly important procedure in the treatment of a variety of conditions, sometimes performed via peripheral access because of concern over major complications associated with central venous catheter (CVC) placement. This study sought to determine the safety and success for ultrasound and fluoroscopically guided, non-tunneled dual lumen CVCs placed for apheresis. Prospective data collection was made of 200 attempted CVC placements in the radiology department utilizing real time sonographic guidance. The complications relating to placement were noted in all and the number of passes required for venepuncture and whether a single wall puncture was achieved was recorded in 185 cases. Duration of catheterization and reason for line removal were recorded in all. Our study group included 71 donors providing peripheral blood stem cells for allogeneic transplant. CVCs were successfully placed in all patients, 191 lines in the internal jugular and seven in the femoral vein. 86.5% required only a single pass and 80.5% with only anterior wall puncture. Inadvertent but clinically insignificant arterial puncture occurred in six (3%) cases. In no case did this prevent line placement. There were no other procedure-related complications. 173 (87.4%) catheters were removed the same day. No catheters were removed prematurely. There was one case of prolonged venous bleeding. Our study demonstrates the safety of central venous catheters for apheresis provided that duration of catheterization is short and real-time sonographic guidance is used for the puncture, and guide wire and catheter placement are confirmed fluoroscopically. (+info)
Three-dimensional ultrasonographic evaluation of ovarian tumours: a preliminary study.
(12/3731)
Our objective was to determine the accuracy of three dimensional (3D) ultrasonography in the differentiation of ovarian tumours. Women (n = 20) with ovarian tumours (13 benign and seven malignant) were first examined using two-dimensional (2D) ultrasonography and were then evaluated with three-dimensional (3D) ultrasonography. All patients underwent surgery within 7 days of 2D and 3D ultrasonographic evaluations, and a histopathological diagnosis was made. A 2D ultrasonographic diagnosis of malignancy was done using an established scoring system. Diagnostic criteria for ovarian malignancy by 3D ultrasonography were: irregular thick septa, irregular papillary projection, mostly solid tumour, high echogenicity, and irregular inner wall. Compared with 2D ultrasound, 3D ultrasound had a significantly higher specificity (P < 0.005) and accuracy (P < 0.01), and a significantly lower false positive rate (P < 0.005). Our results suggest that 3D ultrasonography might be a better means of differentiating between malignant and benign ovarian tumours. However, in view of the small number of ovarian tumours, these observations must be considered preliminary. (+info)
Extended field-of-view sonography: utility in clinical practice.
(13/3731)
The purpose of this study was to evaluate the usefulness of real-time extended field-of view sonography in clinical practice (i.e., the frequency of use in various body systems, the frequency of use by different sonographers, and the benefits and drawbacks in comparison to conventional real-time sonography). The use of extended field-of-view sonography was monitored for a 6 month period. The pattern of usage among different sonographers and for different body systems was documented. Extended field-of-view sonography was utilized in 26.5% of patients. In comparison, color Doppler sonography was used in 23.2% of patients. Utilization of extended field-of-view sonography varied significantly among sonographers and among different body systems. Extended field-of-view sonography allowed measurement of large structures and revealed the anatomic context of abnormalities in circumstances under which conventional real-time scans could not provide this information. (+info)
Evaluation of myocardial, hepatic, and renal perfusion in a variety of clinical conditions using an intravenous ultrasound contrast agent (Optison) and second harmonic imaging.
(14/3731)
OBJECTIVE: To assess the potential of intravenous Optison, a second generation ultrasound contrast agent, and various ultrasound imaging modes to determine myocardial, kidney, and liver perfusion in normal subjects and patients with left ventricular dysfunction or chronic pulmonary disease together with renal or hepatic dysfunction. METHODS: Five normal subjects and 20 patients underwent grey scale echocardiographic imaging of myocardium, kidney, and liver during 505 intravenous injections of Optison. Images were assessed qualitatively by two independent observers and quantitatively using video densitometry to determine the peak contrast enhancement effect. RESULTS: Qualitative analysis showed that intermittent harmonic imaging was superior to either conventional fundamental or continuous harmonic imaging for all organs. Quantitative analysis showed that the peak change in echocardiographic intensity v baseline during continuous harmonic imaging was 11 units for myocardium (p < 0.03), 7 units for kidney (NS), and 14 units for liver (p < 0.05). During intermittent harmonic imaging the peak change was significantly greater, being 33 units for myocardium (p < 0.0001), 24 units for kidney (p < 0.0002), and 16 units for liver (p < 0.001). CONCLUSIONS: Organ tissue perfusion can be demonstrated following intravenous injection of Optison, particularly when used in combination with intermittent harmonic imaging techniques. This contrast agent is effective in a variety of clinical conditions. (+info)
Enhancing availability of the electronic image record for patients and caregivers during follow-up care.
(15/3731)
PURPOSE: To develop a personal computer (PC)-based software package that allows portability of the electronic imaging record. To create custom software that enhances the transfer of images in two fashions. Firstly, to an end user, whether physician or patient, provide a browser capable of viewing digital images on a conventional personal computer. Second, to provide the ability to transfer the archived Digital Imaging and Communications in Medicine (DICOM) images to other institutional picture archiving and communications systems (PACS) through a transfer engine. METHOD/MATERIALS: Radiologic studies are provided on a CD-ROM. This CD-ROM contains a copy of the browser to view images, a DICOM-based engine to transfer images to the receiving institutional PACS, and copies of all pertinent imaging studies for the particular patient. The host computer system in an Intel based Pentium 90 MHz PC with Microsoft Windows 95 software (Microsoft Inc, Seattle, WA). The system has 48 MB of random access memory, a 3.0 GB hard disk, and a Smart and Friendly CD-R 2006 CD-ROM recorder (Smart and Friendly Inc, Chatsworth, CA). RESULTS: Each CD-ROM disc can hold 640 MB of data. In our experience, this houses anywhere from, based on Table 1, 12 to 30 computed tomography (CT) examinations, 24 to 80 magnetic resonance (MR) examinations, 60 to 128 ultrasound examinations, 32 to 64 computed radiographic examinations, 80 digitized x-rays, or five digitized mammography examinations. We have been able to successfully transfer DICOM images from one DICOM-based PACS to another DICOM-based PACS. This is accomplished by inserting the created CD-ROM onto a CD drive attached to the receiving PACS and running the transfer engine application. CONCLUSIONS: Providing copies of radiologic studies performed to the patient is a necessity in every radiology department. Conventionally, film libraries have provided copies to the patient generating issues of cost of loss of film, as well as mailing costs. This software package saves costs and loss of studies, as well as improving patient care by enabling the patient to maintain an archive of their electronic imaging record. (+info)
Branching out with filmless radiology.
(16/3731)
Texas Children's Hospital, a 456 bed pediatric hospital located in the Texas Medical Center, has been constructing a large-scale picture archiving and communications system (PACS), including ultrasound (US), computed tomography (CT), magnetic resonance (MR), and computed radiography (CR). Until recently, filmless radiology operations have been confined to the imaging department, the outpatient treatment center, and the emergency center. As filmless services expand to other clinical services, the PACS staff must engage each service in a dialog to determine the appropriate level of support required. The number and type of image examinations, the use of multiple modalities and comparison examinations, and the relationship between viewing and direct patient care activities have a bearing on the number and type of display stations provided. Some of the information about customer services is contained in documentation already maintained by the imaging department. For example, by a custom report from the radiology information system (RIS), we were able to determine the number and type of examinations ordered by each referring physician for the previous 6 months. By compiling these by clinical service, we were able to determine our biggest customers by examination type and volume. Another custom report was used to determine who was requesting old examinations from the film library. More information about imaging usage was gathered by means of a questionnaire. Some customers view images only where patients are also seen, while some services view images independently from the patient. Some services use their conference rooms for critical image viewing such as treatment planning. Additional information was gained from geographical surveys of where films are currently produced, delivered by the film library, and viewed. In some areas, available space dictates the type and configuration of display station that can be used. Active participation in the decision process by the clinical service is a key element to successful filmless operations. (+info)