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Biomedical subjects

D F Adams

Publications and source records attributed to D F Adams.

At least 37 records · Page 2Linked to original sources
PubMed1996

Small (< or = 3 cm) hyperechoic renal masses: comparison of helical and convention CT for diagnosing angiomyolipoma.

OBJECTIVE: Because hyperechoic renal masses may represent angiomyolipomas or small renal cancers, CT is often used to reveal the fatty component, which allows diagnosis of angiomyolipoma in most cases. Because conventional CT can fail to reveal fat in angiomyolipomas 3 cm or smaller, we conducted a study to determine whether helical CT would improve our detection of fat and allow more of these masses to be diagnosed as angiomyolipomas. SUBJECTS AND METHODS: We used helical and conventional CT to examine 20 masses (5-29 mm in diameter) in 17 patients who had a small hyperechoic mass detected sonographically. Densitometry was performed by three readers and the mean attenuation values were compared. RESULTS: Of the 20 masses, we diagnosed angiomyolipoma in 16 masses using helical CT and in 14 masses using conventional CT. In 11 masses, we found the measured attenuation values to be more negative on helical CT scans than on conventional CT scans. In five masses, we found the opposite to be true. In the remaining four masses, we were unable to diagnose angiomyolipoma. Of the masses that we diagnosed as angiomyolipoma, the mean attenuation value when examined with helical CT (-44 H) was more negative than with conventional CT (-35 H) but not significantly so (p = .058). However, in the subset of patients with masses that were 2 cm or less in diameter (n = 14), the mean attenuation values on helical CT were significantly lower than on conventional CT (-40 H versus -30 H, p < .05). Likewise, for masses with attenuation values that differed by more than 6 H (n = 8), when imaged by the two techniques we again found that mean attenuation values on helical CT were significantly lower (-43 H versus -24 H, p < .05). CONCLUSION: Helical CT revealed angiomyolipoma across all cases as well as conventional CT did. Also, helical CT was more sensitive in revealing fat in masses less than 2 cm in diameter and in masses in which the attenuations of the two CT techniques differed by a significant amount. We preferred helical CT over conventional CT when examining hyperechoic masses for the purpose of diagnosing angiomyolipoma.

Adult↗
PubMed1995

Spiral computed tomography of the liver: contrast agent pharmacokinetics and the potential for improved hepatic enhancement.

RATIONALE AND OBJECTIVES: We conducted a prospective study of 131 patients to evaluate the contrast agent dose-response relationship for liver spiral computed tomography (CT) and to test the hypothesis that spiral CT scanning provides greater enhancement than does dynamic CT scanning. METHODS: Patients were assigned to one of two control groups (dynamic CT) or to one of five experimental groups (spiral CT). Dynamic CT patients received 150 ml and spiral CT patients received either 75, 100, or 150 ml of diatrizoate meglumine. All groups had a monophasic injection rate of 2.5 ml/sec. Hepatic enhancement was compared among experimental and control groups. RESULTS: In the experimental groups, there was a linear dose-response relationship (p < .0001) among the enhancements achieved for the three dosages. The enhancement of the last slice of liver for the spiral CT versus dynamic CT groups receiving 150 ml was significantly greater (p = .002). Peak, first liver slice, and average liver enhancement values were higher with spiral CT scanning, but the difference was not statistically significant (power > .55). CONCLUSION: Using uniphasic injection rates and identical doses of contrast agent, spiral CT scanning has the advantage of improved enhancement of the last part of the liver to be imaged.

Adult↗
PubMed1995

Contrast material-carrying liposomes: biodistribution, clearance, and imaging characteristics.

PURPOSE: To assess the biodistribution, clearance, and computed tomographic (CT) imaging characteristics of interdigitation-fusion (IF) liposomes that carry iotrolan in their aqueous phases. MATERIALS AND METHODS: Biodistribution and clearance of liposomes containing iotrolan produced with the IF method (IF vesicles) were assessed in rats. CT scans of rats and dogs were obtained after injection of IF vesicles at 100 and 250 mg of iodine per kilogram of body weight. RESULTS: A high initial uptake (63%-96% of the injected dose) was found in the liver and spleen. Liver elimination showed half-lives to be 12.9 days at 250 mg of iodine per kilogram, 10.9 days at 100 mg, and 8.7 days at 25 mg. At 250 mg of iodine per kilogram, the rats had an average of 96 HU of hepatic and 321 HU of splenic enhancement. The dogs had 116 HU of hepatic and 65 HU of splenic enhancement. CONCLUSION: IF liposomes have favorable biodistribution, clearance, and imaging characteristics as hepatosplenic contrast agents.

Animals↗
PubMed1995

Interactive MR-guided biopsy in an open-configuration MR imaging system.

PURPOSE: To describe new techniques for percutaneous biopsy with use of an open-configuration magnetic resonance (MR) imaging system with integrated frameless stereotaxic guidance tools. MATERIALS AND METHODS: In 28 patients, biopsy was performed in which the image plane was interactively controlled by the position of a hand-held probe attached to the biopsy needle. An icon integrated into the image was used to guide needle advancement in three planes orthogonal to the needle. In vitro measurements of spatial accuracy were also performed. RESULTS: Diagnostic tissue was retrieved in 25 of 28 patients. The system was most accurate near the isocenter with a maximum measured error of 3.1 mm within a sphere of radius 2.5 cm about the isocenter. CONCLUSION: MR-guided biopsy with a frameless stereotaxic technique is safe and accurate. Image feedback is near real time, and the procedure is interactive. These techniques may be used to perform MR-guided biopsies and to place probes for MR-guided therapies.

Adult↗
PubMed1995

Spiral CT of the chest: comparison of cine and film-based viewing.

PURPOSE: To determine radiologists' ability to find lung nodules on spiral computed tomographic (CT) scans of the chest with both rapid sequential (cine) and conventional film-based viewing. MATERIALS AND METHODS: Eight radiologists searched for lung nodules on spiral CT images (10-mm collimation, 10 mm/sec table speed) presented in two formats. Cine viewing was performed at a computer work-station; sections were viewed in 2-mm increments at frame rates up to 10 frames per second. Film-based viewing of images from a laser printer was performed with a lightbox; sections were viewed at 4-mm increments. Eight 3-5-mm-diameter simulated nodules were superimposed on each of five normal CT scans. RESULTS: Radiologists found a higher fraction of nodules with the cine presentation than with film (mean, 0.69 +/- 0.02 [standard error] versus 0.58 +/- 0.03, respectively [P = .006]). Diameter thresholds for nodule detection (50% correctly localized) were 3.3 and 3.5 mm, respectively. CONCLUSION: Cine viewing of spiral CT images of the chest improved radiologists' ability to detect nodules.

Humans↗
PubMed1995

Periodontal files--a comparative study.

Periodontal files are used by many dentists for instrumentation of root surfaces as a part of periodontal treatment. The purposes of this study were: 1) to examine, evaluate, and compare several periodontal files in 3 different conditions: new, used, and used/sharpened and 2) to evaluate the efficacy of 5 sharpening devices. The main characteristics observed included: the number, shape, and interval of blades; the active, rake, and lip angles; changes induced by wear; the influence of sharpening; and the type of metal surfaces comprising the blades. There was a wide range of active angles on each individual file, from a high of 75 degrees to a low of 51 degrees. The range of active angles for all blades on all new files was even greater, from a high of 87 degrees to a low of 30 degrees. Wear, observed on some but not all blades, was not extensive and appeared either as abrasion or, occasionally, as fracture of the blade edge. Sharpness scores (5 = sharpest and 1 = dullest) for new file blades were also extremely variable and spanned the full range of values, with a majority of blades scoring 3.5 and below. Attempts to sharpen files with several devices produced inconsistent results. All 5 sharpening devices had significant shortcomings. It was concluded that the extreme ranges both in active angles and in sharpness scores probably have a significant influence on effectiveness of root instrumentation.

Dental Instruments↗
PubMed1994

Three-dimensional imaging and display of renal tumors using spiral CT: a potential aid to partial nephrectomy.

OBJECTIVE: A new technique for creating three-dimensional (3D) images of renal tumors using contrast-enhanced spiral computed tomography (CT) is described and preliminarily investigated. METHODS: 3D spiral CT was employed in 2 patients before radical nephrectomy and in 5 patients before partial nephrectomy. Preoperative and postoperative image analyses were conducted to evaluate the ability of the images to depict key anatomic relationships in planning partial nephrectomies. RESULTS: 3D spiral CT defined the tumor's location and relationship to the kidney surface better than the tumor's proximity to renal hilar vessels and collecting system. Negative surgical margins were obtained in all 4 patients with renal cell carcinoma, and post-operative serum creatinine remained less than 2 mg/dL in all 5 patients after partial nephrectomy. CONCLUSIONS: This early experience suggests that 3D spiral CT can help in the planning of partial nephrectomy and in attaining complete resection of renal cell carcinoma while conserving normal renal tissue.

Adult↗
PubMed1994

Expediting the turnaround of radiology reports: use of total quality management to facilitate radiologists' report signing.

OBJECTIVE: The purpose of this study was to determine whether total quality management techniques could be used to speed radiologists' performance on the task of signing reports. SUBJECTS AND METHODS: Total quality management represents a group of tools that can be used to improve the functioning of complex processes in the workplace. The steps involved in our total quality management project were as follows: (1) commit to improving radiologists' performance, (2) commission an interdisciplinary study team, (3) propose hypotheses for the causes of signing delays, (4) identify the key issues constraining performance (Pareto analysis), (5) intervene to correct systematic problems in a test system, (6) evaluate the results of intervention on radiologists' report signing performance, and (7) hold the gains achieved by the intervention. An interdisciplinary study team identified five key obstacles to prompt signing of reports: (1) radiologists' absence from the department when reports were available for signing (e.g., nights and weekends), (2) dysfunctional hand-off between transcriptionist and radiologist, (3) requirement that a fellow or resident sign before a staff radiologist, (4) lack of a system for signing by proxy (if primary radiologist is away), (5) perceived lack of impact of signed report on clinical decision making. RESULTS: Interventions included (1) providing home computer terminals, (2) implementing a buddy system for proxy signing, (3) eliminating the requirement for a signature from a fellow or resident, (4) teaming groups of radiologists with specific transcriptionists, and (5) streamlining transcription service. When these enhancements were used in a test system, the mean time required to sign reports decreased 59% from 26.0 +/- 8.4 hr (mean +/- standard error) in the baseline period to 10.6 +/- 2.9 hr (in the enhanced period, p = .05). CONCLUSION: We conclude that total quality management methods can accelerate radiologists' signing of reports.

Authorship↗
PubMed1994

Small (< or = 3 cm) renal masses: correlation of spiral CT features and pathologic findings.

OBJECTIVE: We describe our 3-year experience using spiral CT in the evaluation of small renal masses in order to determine the usefulness of this technique for classifying the lesions and to correlate specific CT features with pathologic findings. MATERIALS AND METHODS: We retrospectively analyzed spiral CT scans and results of pathologic examinations of surgically extirpated small (< or = 3 cm) renal masses in 35 patients. The masses included 27 renal cell carcinomas, two transitional cell carcinomas, one leiomyoma, one angiomyolipoma, and four benign cysts. Several imaging features, including attenuation, pattern of contrast enhancement, presence and type of calcification, cyst wall, and septation, were correlated with pathologic findings. RESULTS: Most renal cell carcinomas had a solid growth pattern (n = 19), had attenuation values on unenhanced scans of 20 H or greater (n = 26), and had attenuation values that increased by at least 10 H with contrast enhancement (n = 26). Only three renal cell carcinomas were mostly cystic on pathologic examination. Heterogeneous enhancement correlated with the presence of acellular regions (p = .02). Of 12 cystic masses, spiral CT showed the absence of a thick or nodular fibrous capsule in seven of nine masses (specificity, 0.78) and the absence of several (or nodular) septations in six of seven masses (specificity, 0.86) but was not as sensitive in detecting these features. CONCLUSION: Spiral CT can show many of the key imaging features of small renal masses used to distinguish between benign and malignant lesions. However, despite the theoretical benefits of volumetric CT, some lesions remain indeterminate and require surgical removal for diagnosis.

Carcinoma, Renal Cell↗
PubMed1993

Prospective comparison of T2-weighted fast spin-echo, with and without fat suppression, and conventional spin-echo pulse sequences in the upper abdomen.

PURPOSE: To evaluate use of fast spin-echo (FSE) magnetic resonance imaging with and without fat suppression in the liver and upper abdomen. MATERIALS AND METHODS: Conventional spin-echo (SE) T2-weighted, FSE T2-weighted, and fat-suppressed FSE T2-weighted images from 37 patients strongly suspected to have focal hepatic lesions were evaluated. RESULTS: Quantitative analysis demonstrated that fat-suppressed FSE imaging had the highest lesion-liver contrast-to-noise ratio; conventional SE imaging, the lowest. In a qualitative analysis, FSE imaging was preferred. In a rank order analysis, FSE imaging was preferred 83% of the time and fat-suppressed FSE imaging 17% of the time as regards overall image quality; fat-suppressed FSE imaging was preferred 64% of the time, FSE imaging 23% of the time, and conventional SE imaging 13% of the time as regards signal abnormality detection. CONCLUSION: FSE imaging with and without fat suppression is a potentially useful pulse sequence for evaluating the upper abdomen.

Abdomen↗
PubMed1993

Efficacy of 5 machining instruments in scaling of molar furcations.

The scaling efficacy of machining instruments was studied in the furcations of 100 extracted molars. The molars were divided into 5 groups with similar furcation anatomy, painted with artificial calculus, partly submerged in stone blocks, and the furcation entrances covered with a heavy rubber dam material. Ten mandibular and 10 maxillary molars were scaled by an experienced operator with each of the following instruments/inserts: ultrasonic instrument with either a prototype ball point insert or with a new pointed insert; ultrasonic instrument with a ball point insert; reciprocating hand-piece with new inserts for furcations; and a sonic scaler with a universal insert. The molar groups were coded and graded in a stereomicroscope by 2 independent examiners, and the rankings were tested with the Kruskal-Wallis test and the multiple comparisons between treatments test. The results revealed statistically significant differences between the instruments, as well as between different topographical areas of the furcations. The sonic scaler with a universal insert and the ultrasonic instrument with ball point inserts were significantly more efficient (P < 0.05) than the reciprocating handpiece with inserts in most of the areas studied. For mandibular molars, significantly better results (P < 0.05) were obtained for lingual furcation entrances than for furcation roofs. For maxillary molars, significantly better results (P < 0.05) were obtained for distal and buccal entrance areas than for furcation roofs and inside of mesial roots. The present study may give some guidance to the practitioner in choosing machining instruments for furcation cleaning as well as identifying the most difficult topographical areas to instrument.

Analysis of Variance↗
PubMed1993

Hypersensitive dentin: testing of procedures for mechanical and chemical obliteration of dentinal tubuli.

This study examined by scanning electron microscopy the effect of various mechanical and chemical procedures in obliterating dentinal tubuli. Dentin blocks containing open, cross-sectioned dentinal tubuli were separated into one experimental and one control area. The mechanical treatments consisted of 20 seconds of continuous instrumentation with sharp and dull curets, finely textured inserts for the EVA reciprocating handpiece, metal and plastic inserts for a sonic scaler, and metal inserts for an ultrasonic scaler. Chemical treatments included a light-cured dental resin and active obliterating agents including sodium, stannous and hydrogen fluorides, potassium oxalate, glycerin, ferric oxalate, and potassium nitrate. These substances were applied to the test surfaces for 2 minutes and allowed to dry. One half of the chemically treated specimens were then sprayed with water in order to evaluate the retention of the obliterating agents. The results revealed that among the mechanical treatments, the sharp curet gave the most consistent and complete obliteration of the tubuli. The plastic inserts had no tubular occluding effects. Among the chemical procedures, the light-cured resin resulted in the most complete obliteration of the tubuli, while the fluoride agents and glycerin had no effect. It can be hypothesized that combining instrumentation with a sharp curet causing a heavy smear layer and occlusion of tubuli apertures, followed by application of a light body resin, may prove to be a rational method of desensitizing hypersensitive dentin surfaces. However, this combined treatment should be evaluated in clinical trials.

Curettage↗
PubMed1993

Pain and discomfort levels in patients during root surface debridement with sonic metal or plastic inserts.

The study was designed to evaluate whether root surface debridement with a sonic scaler plastic insert would cause less pain and discomfort to patients than an ordinary, probe-shaped metal sonic insert. One quadrant in each of 23 patients was debrided with each insert. Blood pressure, mean arterial pressure, and heart rate were monitored before, during, and immediately after each treatment. Pain was also evaluated on a visual analogue scale (VAS) after each treatment, as well as 2 weeks later following pain-provoking stimuli. Blood pressure, mean arterial pressure, and heart rate did not reveal any differences between quadrants treated with plastic or metal inserts. Heart rate had a weak, positive association with treatment time. The VAS gave a higher pain score for the plastic (30.8) than for the metal insert (24.4), but this difference was not statistically significant (P = 0.055). Following pain-provoking stimuli at the 2-week follow-up visit, quadrants debrided with the metal insert (31.3) scored significantly lower (less pain) (P < 0.01) on the VAS than quadrants treated with the plastic insert (30.7). It is concluded that the sonic metal insert caused less pain and discomfort to the patients due to its superior accessibility and water spray cooling. The significant difference between metal and plastic tip debrided quadrants at the follow-up visit was probably caused by the smearing effect of the metal insert with partial closure of the dentin tubule orifices.

Adult↗
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

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

Relative proportions of pathogen-related oral spirochetes (PROS) and Treponema denticola in supragingival and subgingival plaque from patients with periodontitis.

The purpose of this study was to use monoclonal antibodies to enumerate spirochetes in dental plaque, including the newly recognized pathogen-related oral spirochete (PROS) and specific serovars of Treponema denticola. Plaque was collected from control subjects with no apparent periodontal disease and from sites of moderate to severe chronic periodontitis in patients with inflammatory periodontal disease. Individual monoclonal antibodies were used to determine whether spirochetes were present and then a double-staining protocol was employed to count total spirochetes and specific treponemes in individual microscopic fields. Results indicate that spirochetes are more common at diseased sites and in subgingival plaque than at healthy sites or in supragingival plaque. Together PROS and T. denticola comprised the majority of all spirochetes in all samples and PROS and T. denticola serovars "B" and D were most numerous in plaque from patients with periodontitis. PROS were the majority of all spirochetes in supragingival plaque (76.2% +/- 23.8%) and subgingival plaque (60.9% +/- 19.1%) from periodontitis patients, significantly larger than the percentage of T. denticola serovar "B" (P less than .001 for both supragingival and subgingival plaque) and serovar D (P less than .01 for supragingival and P less than .001 for subgingival plaque). These observations indicate that PROS are the predominant spirochete in plaque from sites of patients with periodontitis, but other analytical approaches are necessary to determine if PROS or T. denticola are pathogenic.

Adult↗
PubMed1992

Root dentin morphology after different modes of citric acid and tetracycline hydrochloride conditioning.

The purpose of this study was to assess the effect of citric acid and tetracycline HCl application to dentin surfaces by a "passive dripping" or an "active burnishing" technique. Twenty dentin blocks were prepared from freshly extracted non-diseased human impacted third molars. The blocks were root planed and randomly assigned to two groups for treatment with either citric acid or tetracycline HCl. The duration of treatment was 30, 60, 120, or 240 seconds. Control blocks were treated with distilled water. After treatment the blocks were processed for observation and measurements in the scanning electron microscope (SEM). Application of either of the acid solutions resulted in removal of the smear layer. Measurements indicated a time dependent increase in the mean dentinal tubule orifice diameter ranging from 1.05 microns in control specimens to 3.18 microns after 4 minutes treatment (citric acid group). The increase in tubule diameter was significantly greater (P less than or equal to 0.01) for both citric acid treatment modalities than tetracycline HCl treatment. There was also a time dependent increase in the depth of penetration as measured by a trumpeting of the tubule profiles, and this penetration was significantly greater (P less than or equal to 0.01) after citric acid treatments. Passive or active application of the acids did not seem to have any major impact on the measurements or on the surface morphology. It was concluded that citric acid causes more extensive changes than tetracycline HCl and that the mode of application of the agent is probably not critical.

Acid Etching, Dental↗