PubMed Health⌕ Search

Biomedical subjects

S E Seltzer

Publications and source records attributed to S E Seltzer.

At least 19 recordsLinked to original sources
PubMed1992

Practices and attitudes about cathode-ray tube-based and film-based image interpretation.

A questionnaire was mailed to 708 practicing radiologists and 348 members of the Society for Computer applications in Radiology (SCAR) in order to evaluate current practices and attitudes regarding the perceived advantages or disadvantages of film- and CRT-based image interpretation. A total of 27% of the 1,056 questionnaires (137 practicing radiologists; 145 SCAR members were returned. Ninety percent of practicing radiologists used film at least 75% of the time. Advantages of film-based reading listed by more than 75% of the respondents included: film reading is faster, and facilitates viewing multiple images. Advantages of CRT-based reading included: access to the entire dynamic range and potential imaging processing. Desirable attributes of existing displays included: adjustable grey scale, magnification, ability to view multiple images, allow quick review, and viewing by several individuals. Valued potential advances included: multiple higher resolution monitors, image processing and multimodality display. Practicing radiologists and computer applications society members had similar attitudes. Film-based reading is still nearly universal, but radiologists are interested in CRT-based reading if such devices have the proper features and become more available.

Attitude of Health Personnel↗
PubMed1992

Marketing CT and MR imaging services in a large urban teaching hospital.

A three-phase marketing program was implemented to increase referrals for examination with computed tomographic (CT) or magnetic resonance (MR) imaging and improve services in an academic radiology department. In the research phase, a data base of 135 referring physicians was developed, and a questionnaire was mailed to 130 physicians. The market research identified three key issues: waiting time to get an appointment, scheduling procedures, and communication of findings. In the implementation phase, additional equipment was installed and a program of expanded appointments, service improvements, and public relations was introduced. In the evaluation phase, 1 year after the completion of phase 2, the effect of the marketing program was measured. The average number of physicians who made referrals per month increased from 609 to 653 (an increase of 7.2% over baseline); the average number of CT and MR examinations performed each month increased by 57.3% and 45.2%, respectively. Referrers' ratings of 10 imaging services improved significantly (P = .02). It is concluded that a well-designed marketing program can boost the productivity of a teaching hospital department.

Appointments and Schedules↗
PubMed1992

Reading and decision aids for improved accuracy and standardization of mammographic diagnosis.

Image-reading and decision aids were designed to improve the accuracy of mammogram interpretation. The reading aid was a list of diagnostic radiographic features and scales for quantification of each feature. The decision aid, a computer program, converted the reader's scaled values, weighted for predictive power, into an advisory estimate of the probability of malignancy. The features were identified and their importance was assigned in four steps: (a) interviews of five expert readers to establish an initial set of features, (b) perceptual tests to refine the feature set, (c) a consensus meeting to refine this set and establish nomenclature and scales, and (d) the expert's scaling of each feature in a set of 150 mammograms. Those scaled judgments were analyzed to provide the final list of features and their relative importance and to program the computer decision aid. To test the enhancement effect, six other radiologists interpreted a different set of mammograms without, and later with, the two aids. Receiver operating characteristic analysis showed a gain of approximately 0.05 in sensitivity or specificity when the other value remained at 0.85. In a subset of the more difficult cases, the enhancement effect was approximately 0.15 in either sensitivity or specificity.

Humans↗
PubMed1992

Improved radiology film library operations.

An interdisciplinary task force at the authors' institution developed a design for a new film library that placed heavy emphasis on service to its customers. The task force established locations and staffing for "satellite" inpatient film libraries organized by clinical specialties. Inpatient films were not permitted to be taken from the radiology department but were available for 24-hour viewing. Film locations were recorded in the radiology information system. Reorganization led to important improvements in film library operations and in the clinical staff's opinion of film library service. Objective measures of performance, such as the fraction of requested films available for conferences, showed significant improvement (P less than .001). Closer working relationships developed between film librarians, radiologists, and their clinical colleagues. Film library personnel were recruited more easily and stayed on the job longer. Several hundred thousand film-tracking transactions per year were recorded. The authors conclude that decentralization of certain film library activities improved many critical aspects of performance.

Libraries↗
PubMed1992

Needle-tip localization during CT-guided abdominal biopsy: comparison of conventional and spiral CT.

OBJECTIVE: This study was performed to determine whether the time required for needle-tip localization during biopsy of the abdomen would be reduced if continuous-volume data acquisition, also known as spiral CT, were used for guidance instead of conventional CT. SUBJECTS AND METHODS: Forty patients had biopsies of an abdominal mass; half underwent needle-tip localizations with conventional CT and half with spiral CT. The times required to localize the needle for 104 needle passes were calculated; scanning and reconstruction times were included, and the radiologist's technique and procedural difficulties were deliberately excluded. The mean needle localization times with conventional and spiral CT were compared for the upper abdominal and pelvic regions by using the two-tailed unpaired Student's t-test. RESULTS: The mean time (+/- SE) for spiral CT was 35 +/- 2 sec compared with 105 +/- 18 sec for conventional CT (p < .001). When analyzed by region, times with spiral CT were shorter in both the upper abdomen (means, 37 sec for spiral CT vs 150 sec for conventional CT, p < .001) and pelvis (means, 25 sec for spiral CT vs 74 sec for conventional CT, p = .038); the magnitude of the improvement was greater in the upper abdomen. CONCLUSION: The time required to find the needle tip during guided biopsy of an abdominal mass is reduced with spiral CT compared with conventional CT. This improvement is partly a result of the ability to eliminate respiratory misregistration with spiral CT, which is not possible with conventional multisectional CT; hence the greater advantage in upper abdominal biopsy.

Abdominal Neoplasms↗
PubMed1991

Visualization and detection-localization on computed tomographic images.

These studies investigated observers' ability to detect and locate highly visible liver lesions on computed tomographic (CT) images, manipulating both the lesion's location and polarity (brighter or darker than liver background). Visibility of a lesion is not sufficient to guarantee accurate localization. With clinical images, possible confusions between a lesion and coexisting normal structures (like blood vessels) is a serious constraint on observer performance.

Humans↗
PubMed1991

Current use of screening laboratory tests before abdominal interventions: a survey of 603 radiologists.

A survey of 2,153 radiologists was conducted to assess both their current practices of evaluating hemostatic function and their use of blood tests before performing image-guided nonvascular abdominal interventions. Among the 603 (28%) who responded, more radiologists routinely perform prothrombin time (81%) or partial thromboplastin time (78%) tests than platelet counts (59%), and relatively few (7%) obtain bleeding times. The most common practice (51%) is to order all of the first three tests. Use of laboratory tests is quite common (greater than 75%) before biopsy of splenic masses, hemangiomas, or hepatomas and before all catheter insertions. These tests are used less frequently (less than or equal to 70%) before fine-needle procedures, including biopsy and cyst aspiration. Only one-third of the radiologists alter their evaluation in patients who have taken aspirin. Most respondents (64%) believe that there should be written guidelines on how to evaluate patients before interventional procedures. Virtually all (97%) thought such evaluation should be the radiologist's responsibility.

Aspirin↗
PubMed1990

Biodistribution and clearance of contrast-carrying MREV liposomes.

Contrast-carrying liposomes (CCLs) have been shown to increase the attenuation coefficient of the liver and spleen during computed tomographic (CT) imaging. A modification of the reverse-phase evaporation preparative technique ("MREV") led to production of CCLs that entrap contrast media efficiently. After intravenous injection, MREVs are phagocytized by the Kupffer cells of the liver and the macrophages of the spleen. The biodistribution and clearance of MREVs were studied to evaluate their potential for clinical use, MREVs carrying iodine-125-iotrolan were administered intravenously to 12 rats at doses of 400 mg lipid (containing 400 mg iodine) per kilogram body weight. Pairs of rats were anesthetized and scanned at 3 hours, and 1, 7, 14, 27 and 48 days; CT attenuation values of liver, spleen, blood, kidneys and bladder were measured. Immediately following CT, the rats were killed and tissue specimens were radioassayed. Maximum iodine content in liver and spleen was reached at one day and sustained at high levels for seven days. Biologic removal half-time of the agent in both the liver and spleen was six days. Maximum CT enhancements over baseline were observed at 24 hours and reached 210 delta HU in the liver and 880 delta HU in the spleen per gram iodine injected per kilogram body weight. It is concluded that MREVs have appropriate imaging characteristics, biodistribution, and clearance to be effective CT contrast agents.

Animals↗
PubMed1990

Production and characterization of improved liposomes containing radiographic contrast media.

The authors have investigated liposomes prepared by the reverse-phase evaporation method (REVs) and a modification of this technique that employs a microemulsifier (MREVs), for the delivery of radiographic contrast media (RCM) to the liver and spleen. The modification entailed substituting a Microfluidizer (Microfluidics Inc., Newton, MA) for the sonication step of the REV technique. The MREV procedure is amenable to large-scale production and continuous-flow operation and yields products with high RCM encapsulation. Efficiently entrapped are ionic, high-osmolar diatrizoate (24.38 +/- 2.62% versus 8.35 +/- 0.55%; MREV versus REV), and nonionic, low osmolar Iotrolan (Schering AG, Berlin, FRG) (24.84 +/- 2.13% versus 7.25 +/- 1.19%) RCM with iodine-to-lipid ratio of 1.5:1. The MREV procedure, therefore, has practical advantages over the REV method. High liver and spleen uptakes of Iotrolan-containing vesicles were noted in normal rats. The diatrizoate MREVs lost their contents on contact with serum, resulting in urinary excretion of this agent. Computed tomography values of splenic and hepatic sections, 1 hour after intravenous injection of Iotrolan MREV (500 mgI/kg), are 0.78, and 0.08 Hounsfield Units (HU)/mgI/kg, respectively (versus 0.01, and 0.006 HU/mgI/kg for free Iotrolan).

Animals↗
PubMed1988

Evaluation of the dehydration-rehydration method for production of contrast-carrying liposomes.

We measured the amounts of three types of radiographic contrast media (RCM) that could be entrapped in liposomes prepared by the dehydration-rehydration vesicle (DRV) technique. To make DRVs, one initially makes water-containing, small unilamellar vesicles, adds contrast media and lyophilizes the mixture. Upon rehydration, the DRVs re-form, passively entrapping RCM. Diatrizoate, iohexol and iotrolan proved to be entrappable in similar amounts (diatrizoate was best), but all of these amounts were less than for other small molecules, such as carboxyfluorescein (P less than 0.05). Entrapment was directly proportional to lipid concentration (r = 0.76; P less than 0.002), and inversely related to iodine concentration (r = 0.86; P less than 0.002). Under ideal conditions with neutral lipids, 19.45 +/- 9.9% of diatrizoate was entrapped, corresponding to 1.05 +/- 0.50 g I per g lipid. These values are close to those achievable for large unilamellar vesicles. Use of an automated mixing device (the Microfluidizer) in place of sonication, facilitated production of large liposome batches and improved entrapment (P less than 0.05). Computed tomography (CT) scans of rats showed 30 and 218 HU of liver and spleen enhancement, respectively, per g I/kg injected DRVs. These studies showed this method (possible augmented by the Microfluidizer) allows efficient production of contrast-carrying liposomes.

Animals↗
PubMed1988

Size discrimination in computed tomographic images. Effects of feature contrast and display window.

Studies show that features on computed tomographic (CT) images in clinical formats become less detectable when the images are produced with wider CT display windows. We studied the effects of feature contrast and the display window on observer performance in higher-order tasks that involved discriminating small size differences between features on CT images. The features to be discriminated were pairs of disks (9.0 or 9.5 mm in diameter) superimposed on CT images of water phantoms. Sets of image stimuli for two different types of size-discrimination tasks were generated with various CT contrasts specified for the superimposed features and were produced on film transparencies with display windows ranging from 90 to 2880 Hounsfield units (HU) in width. Observers' performance improved with increasing CT contrast in both size discrimination tasks. Unlike performance in feature-detection tasks, however, size discrimination was unaffected by changing the CT display window over a factor of 16 (from 90 to 1440 HU). Performance fell only at the widest display window (2880 HU), for which CT noise was essentially invisible. These results suggest that the effect of changing the CT display window may depend on the spatial frequency content of image information required for a given task.

Humans↗
PubMed1988

Contrast-carrying liposomes. Current status.

The goal of recent research has been to encapsulate standard, water-soluble radiographic contrast media (RCM) into liposomes, in order to direct them to reticuloendothelial tissues. Toward this end several varieties of contrast-carrying liposomes (CCLs) have been prepared. Each of these has proven effective in opacifying the liver and spleen of animals on computed tomography (CT). The suitability of two new encapsulation techniques: (1) Microemulsification (MELs), and (2) Dehydration Rehydration Vesicles (DRVs), for CCL production has been explored recently. Each of these two new preparative techniques were valuable in the effort to "scale-up" the CCL production process, leading to "pharmaceutically acceptable" preparation.

Animals↗
PubMed1988

Chronic osteomyelitis: the relative roles of scintigrams, plain radiographs, and transmission computed tomography.

We evaluated the relative contribution of transmission computed tomograms (CT), plain radiographs, and bone/gallium scans in the diagnosis of 27 patients with suspected active chronic osteomyelitis. All patients were imaged with all modalities and had surgical proof of the presence or absence of disease. At surgery, osteomyelitis was shown to be active in 20 patients, 15 of whom had sequestra, and inactive in the remaining seven. CT depicted all 15 sequestra, but was falsely positive in three patients, all of whom had bone remodeling only and had negative bone/gallium scintiscans. Plain radiographs had a limited value; they detected sequestra, which was the only findings to indicate the presence of active disease, in 5 patients out of the 15 with surgical proof thereof. The authors conclude that, considering the shortcoming of other modalities with regard to depicting sequestra, scintigraphy is helpful in confirming the presence or absence of active disease and therefore in preventing unnecessary surgery.

Adult↗
PubMed1987

Analysis of the tethered-bowel sign on abdominal CT as a predictor of malignant ascites.

The value of the "tethered-bowel sign" as a predictor of the nature of intraabdominal fluid was assessed. In the presence of moderate amounts of abdominal fluid, the sign was said to be positive if small or large bowel loops were not seen to float freely on computed tomographic (CT) images, and did not make contact with the anterior abdominal wall. A positive sign was significantly associated with the presence of malignant cells in the fluid (P less than 0.005). When equivocal cases were excluded, the sign had a sensitivity of 85%, a specificity of 93%, and an accuracy of 88%. In the study population (64% prevalence of malignant fluid), the sign had a positive predictive value of 96%, but a negative predictive value of only 78%. When equivocal cases were included, the sensitivity dropped to 69%, the specificity to 78%, and the accuracy to 72%. It is concluded that CT evidence of tethered-bowel loops strongly suggests a malignant cause of ascitic fluid.

Adult↗