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Biomedical subjects

K D Hopper

Publications and source records attributed to K D Hopper.

At least 37 records · Page 2Linked to original sources
PubMed1997

Thoracic spiral CT: delivery of contrast material pushed with injectable saline solution in a power injector.

A method of power injection of contrast material pushed with injectable saline solution during thoracic computed tomography (CT) was evaluated in 75 patients to help decrease the amount of contrast material necessary. Patients received 50-125 mL of 60% nonionic contrast material alone or pushed with 50 mL of saline. A volume of 75 mL of contrast material pushed with saline provided enhancement of the thoracic vasculature equal to that provided by a 125-mL volume of contrast material administered alone (P < .001) and caused significantly less beam-hardening artifact (P < .01).

Aorta, Thoracic↗
PubMed1997

Gel tubes: a method of core-specimen retrieval and transport.

The utility of saving core biopsy specimens in sterile gel tubes was evaluated with 30 liver and 30 kidney core specimens obtained at open biopsy with an 18-gauge needle during autopsy. The core specimens were saved with one of three methods: gel tube, formalin swirl, or scalpel retrieval. The combined-organ mean time for the radiologist to save core specimens was not statistically significantly different with gel tubes (3.8 seconds) and the formalin-swirl method (4.5 seconds). Both of these methods, however, were significantly faster than the scalpel-retrieval method (11.2 seconds) (P < .001). The combined radiologist and cytotechnologist time was greatest with the gel tubes (35.1 seconds vs 14.7 and 21.2 seconds, respectively). Core specimens were broken with the formalin-swirl and scalpel-retrieval methods but not with the gel-tube method.

Biopsy, Needle↗
PubMed1997

The breast: in-plane x-ray protection during diagnostic thoracic CT--shielding with bismuth radioprotective garments.

PURPOSE: To evaluate the ability of thin overlying bismuth radioprotective shielding to reduce the x-ray dose to radiosensitive superficial organs during diagnostic computed tomography (CT). MATERIALS AND METHODS: A variety of patient and phantom studies were performed with four thicknesses of bismuth radioprotective latex over the breast. Dose savings were determined with thermoluminescent dosimeters. A prototype and then a final manufactured radioprotective brassiere was constructed and tested for radiation dose savings to the breast during diagnostic chest CT. Preliminary studies were also performed to evaluate shielding of the thyroid, orbit, and testes. RESULTS: The use of bismuth radioprotective latex saved an average 57% of the radiation dose to the breast from thoracic CT, decreasing the radiation level from an average 2.2 rad (0.022 Gy) to 1.0 rad (0.010 Gy) (P < .001). Preliminary tests of shielding other superficial radiosensitive organs frequently included at diagnostic CT (eyes, thyroid gland, and testes) were performed with the same thickness of overlying bismuth radioprotective latex, with similar results. Radiation to the thyroid gland was reduced by 60% (from 0.0573 to 0.0229 Gy) and radiation to the eye and testes was reduced by 40% (from 0.0256 to 0.0154 Gy) and 51% (from 0.0463 to 0.0229 Gy), respectively. CONCLUSION: The use of in-plane overlying bismuth radioprotective latex manufactured into form-fitting garments did not affect the diagnostic CT image but reduced the amount of radiation to radiosensitive superficial structures.

Adult↗
PubMed1997

Evaluation of contrast densities in the diagnosis of carotid stenosis by CT angiography.

OBJECTIVE: This study assesses intravascular density produced by ionic and nonionic contrast material and its effect on visualization of stenoses by CT angiography. MATERIALS AND METHODS: CT angiography was performed using a 32-vessel phantom to study grades of luminal stenoses (0-100%), three lengths of stenoses (1, 3, and 5 mm), and two angles of inclination into the stenoses (45 degrees and 75 degrees). Scans were obtained with a slice thickness of 2 mm, a slice interval of 1.5 mm, a pitch of 1.0, a voltage of 120 kV, and a current of both 100 and 200 mA. Vessels were oriented parallel to the z-axis, and opacified with ionic and nonionic contrast material that had densities of 100, 150, 200, 250, 300, and 350 H. Cross-sectional luminal diameters were measured in and out of the stenoses. Edge definition and halo artifact for each vessel were graded by an investigator who was unaware of the contrast material density used. RESULTS: A contrast density of 150 H as revealed by CT angiography yielded the most accurate stenosis measurements with ionic contrast material. For nonionic contrast material, attenuation values of 150 and 200 H produced the best results on CT angiography. A density of 100 H or greater than 250 H significantly increased the error of vessel measurement (p = .001) for both types of contrast material. For the two current levels tested (100 and 200 mA), no statistical difference was found. CONCLUSION: The accuracy of CT angiography in measuring carotid stenosis depends on the luminal attenuation value. An optimum contrast density is 150 H for ionic contrast material; for nonionic contrast material, 150-200 H (at the window and level settings of 300 H and 40 H).

Carotid Arteries↗
PubMed1997

Technical factors of CT angiography studied with a carotid artery phantom.

PURPOSE: To evaluate scanning parameters (conventional versus spiral CT, section thickness, and pitch) and vessel orientation in the performance of CT angiography. METHODS: Conventional CT and 1.0-, 1.5-, and 2.0-pitch spiral CT acquisitions of a carotid phantom designed with vessels oriented parallel to the z-axis, 45 degrees oblique, and perpendicular to the z-axis were obtained with section thicknesses of 2, 4, and 8 mm. The phantom contained 32 vessels with 0% to 100% stenoses. Normal and stenotic luminal diameters were measured and the number of artifacts was assessed. RESULTS: No overall difference was observed among conventional and spiral CT acquisitions obtained with pitches of 1.0, 1.5, and 2.0. With thicker sections, CT angiographic accuracy decreased and artifacts increased. The three-vessel orientations were relatively comparable in accuracy in terms of the percentage of stenosis measured. Vessels parallel to the z-axis suffered less artifactual degradation. Unique artifacts, such as luminal distortion and beam hardening, were observed in vessels oriented at 45 degrees and perpendicular to the z-axis. CONCLUSION: Use of thinner sections with vessels oriented parallel to the z-axis optimizes CT angiographic quality. There is no apparent degradation with the use of spiral CT, and a pitch of 1.5 or 2.0 provides results equivalent to 1.0-pitch spiral studies.

Brain Ischemia↗
PubMed1996

"Robo-Rad": an inexpensive user-friendly multimedia report system for radiology.

BACKGROUND AND PURPOSE: The complex information obtained by CT, MR, and ultrasound examinations is often difficult to convey with a written report. Today's multimedia computer technology provides a medium within which the audio and the visual components of a radiologic consultation can be made available simultaneously, with the projected capability of remote access from any personal computer. A system was developed to run on low-end computer systems with image quality adequate for reporting purposes and prudent memory management (each report occupies < 4 MB). With this system-"Robo-Rad"-the image and radiologist are recorded simultaneously while he or she describes and points out (with a mouse) areas of interest. This dynamic report, along with patient data, can be retrieved and viewed by the consulting physician at his/her convenience using a low-end PC or Macintosh computer. MATERIALS AND METHODS: To assess the clinical utility of Robo-Rad, survey responses were solicited from clinical physicians at the Penn State University Hospital (41.5% faculty/fellows, 31.7% residents, 11.8% medical students, 2% clinical nursing; n = 101) during a hands-on demonstration using studies of 35 consecutive inpatients whose CT scans had been dictated into the system. RESULTS: In an average week, the surveyed professionals ordered 3.2 +/- 3.0 CT studies, reviewed 3.8 +/- 3.0 CTs, spent 1.5 +/- 2.0 hours locating Ct studies, and discussed 2.3 +/- 1.9 CT cases with a radiologist. The average time spent discussing a single CT case with a radiologist was reported as 9.4 +/- 5.9 minutes. On a five-point rating scale (1 = not at all to 5 = very much so), respondents indicated that the Robo-Rad report was helpful (4.3 +/- 0.7) and provided clinically important information that would be difficult to convey with current dictation systems (4.2 +/- 0.8). Desire to discuss the case with a radiologist in addition to viewing the Robo-Rad report scored 3.2 +/- 1.0. If such a system were readily available, 91.8% of the respondents indicated that they would use it in addition to the currently available written report and audio dictation system, and 96.6% would use it instead of the current system. Local area network and modems were the modalities of highest interest for remote access (69.3% and 44.6%, respectively). CONCLUSIONS: Judging by these data, the Robo-Rad system would be of benefit to clinicians. It provides a user-friendly, low-cost multimedia radiology report utilizing readily available technology to improve radiologist-clinician communication.

Attitude of Health Personnel↗
PubMed1996

Take-home informed consent for intravenous contrast media: do patients learn more?

RATIONALE AND OBJECTIVES: In 1978, Morrow et al published the results of a simple technique for raising radiation oncology patients' levels of awareness about medical options. They reported that providing written information at least 24 hours in advance was an effective tool for increasing the baseline knowledge in this patient group. However, Morrow's cohort consisted exclusively of cancer patients receiving radiation therapy. The authors of this article are concerned with whether the encouraging results reported by Morrow are reproducible when applied to patients awaiting invasive radiologic procedures. METHODS: One hundred sixty consecutive outpatients awaiting contrast were block randomized into one of eight groups based on age, sex, and previous contrast exposure. For each group, half were given their consent form at least 24 hours prior, and the other half at the time of their procedure. All patients were tested at the time of their procedure to evaluate knowledge retention. RESULTS: Comparison between the two study groups showed no overall statistically significant differences either in knowledge (experimental group 4.7 +/- 1.32 versus 4.38 +/- 1.30 control group) or level of satisfaction. Additionally, individuals experienced with contrast failed to outperform those who had never previously been given contrast. There is no significant difference in the performance between the two sexes regardless of group. CONCLUSIONS: The providing of information 24 to 72 hours in advance of an invasive procedure does not have a beneficial effect over just providing the same information at the time of the study.

Age Factors↗
PubMed1996

Patient allergies: role in selective use of nonionic contrast material.

PURPOSE: To determine which aspects of patient allergies allergists and immunologists would recommend for the selective use of nonionic contrast material. MATERIALS AND METHODS: A survey about allergy and the selective use of nonionic contrast material was sent to 1,017 allergists and immunologists. RESULTS: Of 287 respondents, 262 believed that a non-contrast material-related allergy alone was not an indication for use of nonionic contrast material. Most (n=219) believed that a previous serious or life-threatening reaction was the best indication and that a minor reaction was not an indication. Most respondents believed that patients with any previous reaction to contrast material should receive nonionic contrast material, steroids and then nonionic contrast material, or no contrast material at all. CONCLUSION: Use of nonionic contrast material in patients with previous non-contrast material-related allergic reactions should be limited to patients with previous serious or life-threatening reactions.

Contraindications↗
PubMed1996

Analysis of interobserver and intraobserver variability in CT tumor measurements.

OBJECTIVE: The purpose of this study was to evaluate the variability between radiologists interpreting thoracic and abdominal/pelvic CT scans in selecting specific sites of metastatic tumor for measurement (indicator lesions) and to assess interobserver and intraobserver variability in tumor measurement. MATERIALS AND METHODS: Three separate experienced radiologists were asked to review 24 combined thoracic and abdominal CT scans in patients with metastatic tumor. Each radiologist was asked to identify the indicator lesions representative of each patient's tumor bulk. In the second phase of the study, 105 specific foci on 26 combined thoracic and abdominal CT studies (including the original 24) were reviewed twice by the same three radiologists. Up to eight foci were randomly identified per patient, and each observer was asked to determine the slice with the maximum diameter for each tumor focus and to measure it in three dimensions (maximum diameter, its perpendicular, and length). RESULTS: A total of 132 tumor sites were present on the CT studies in phase I, all of which were chosen by at least one observer as an indicator lesion. Of the 116 of these that were separate and nonoverlapped, 57 (49%) were measured by only one observer, whereas 32 (28%) and 27 (23%) were measured by two or all three observers, respectively. Observers were more inclined to pick round or defined/well-defined lesions rather than irregular, oval, or poorly defined ones, although this tendency was not statistically significant. The second phase of the study showed considerable interobserver variability (15%) in CT tumor measurement, which was worse for poorly defined and irregular lesions. Intraobserver variability in measuring individual foci was less (6%). CONCLUSION: Radiologists interpreting thoracic and/or abdominal/pelvic CT scans for metastatic cancer should measure and report a significant number of each patient's tumor sites, especially larger ones in different anatomic areas. When interpreting a follow-up CT scan of a patient with metastatic cancer, the interpreting radiologist should remeasure the indicator lesions on the previous and on the follow-up CT scans, especially when the results will change the patient's treatment response category.

Abdominal Neoplasms↗
PubMed1996

Routine use of a higher order interpolator and bone algorithm in thoracic CT.

OBJECTIVE: This study was designed to evaluate the utility of the routine use of high spatial frequency algorithms and higher order helical interpolators for imaging lung parenchyma during routine thoracic CT. SUBJECTS AND METHODS: We evaluated 50 consecutive patients undergoing clinically indicated thoracic CT using the same imaging parameters and scanner. The helical volume was reconstructed three separate times using standard and higher order (180 degrees linear with double-sided lobes) interpolators and standard and high spatial frequency (bone) algorithms. The images were photographed and given to five separate readers who were kept unaware of the interpolator and algorithm and who were asked to evaluate simultaneously each patient's three sets of images for best, in-between, and worst images of the lung interstitium, pathology, and normal anatomy. RESULTS: All five readers rated the standard interpolator and algorithm images as the worst (p < .01). All five readers consistently rated the double-sided lobe interpolator and bone algorithm images as the best (p < .01). CONCLUSION: A second reconstruction of routine thoracic helical CT data using higher order helical interpolators and a bone algorithm significantly improves interstitial detail of lung parenchyma and overall visualization of normal anatomy and pathologic processes.

Aged↗
PubMed1995

Three-dimensional quantitation of pediatric tumor bulk.

In pediatric oncology, therapeutic decisions are made based on tumor response to chemotherapeutic agents. Sequential measurement of tumor bulk and its percent change on therapy must be accurately assessed. Will 3-dimensional (3-D) volumetric determination improve our ability to assess tumor response to therapy? Forty-five CT scans of pediatric patients with unresectable thoracic or abdominal neoplasia were assessed for tumor bulk by the standard "2-dimensional (2-D)" volume formula (cross-sectional area x length) and by 3-D volumetric analysis. Thirty-two examinations were performed in follow-up, and percent change in tumor size was calculated. The 2-D volume calculation overestimated tumor volume by more than 50% on all but two examinations when the 2-D volume was compared with the 3-D volume. In 28% of follow-up examinations, the 2-D calculation of percent change differed by more than 10% from the 3-D volume. Fifteen percent differed by over 25%. This changed the response category of one patient from "no response" to "partial response". 3-D volumetric analysis, easily performed by a trained technologist, will give more accurate assessment of the actual tumor bulk and its subsequent changes in size in response to therapy.

Abdominal Neoplasms↗
PubMed1995

Fractures of the acetabulum: imaging, classification, and understanding.

For the patient with a traumatized acetabulum, accurate radiographic diagnosis and classification are the cornerstone of effective clinical care. The classification system of Judet and Letournel has led to improved management of such injuries. However, trauma-related acetabular fractures are often complex, with multiple fragments and secondary fracture lines. Furthermore, the Judet and Letournel system is complicated and easily misunderstood, reflecting the nature of the anatomy itself. Computed tomography (CT) provides information regarding the extent of the fracture and is complementary to radiography for ascertaining the spatial arrangement of fracture fragments. Three-dimensional (3D) reconstruction of CT data can be helpful in understanding the complex fracture patterns. These are divided into two main types: elementary fractures, which consist of injuries to a single structural component, and associated fractures, which are combinations of the elementary types. Three-dimensional CT is especially helpful in gaining perspective on the fracture orientation. Although questions remain as to its clinical application, 3D CT is a useful teaching tool for demonstrating the different types of acetabular fractures.

Acetabulum↗
PubMed1995

Fine-needle aspiration biopsy versus fine-needle capillary (nonaspiration) biopsy: in vivo comparison.

PURPOSE: To evaluate, in vivo, the efficacy of fine-needle capillary (nonaspiration) biopsy (FNCB) versus fine-needle aspiration biopsy (FNAB) when performed at the same site with a coaxial technique. MATERIALS AND METHODS: In 91 patients, biopsy was performed at 140 sites in 93 lesions mostly throughout the chest and abdomen with either FNCB or FNAB, or both (98 sites). A coaxial technique with a 22-gauge needle was used. The quality of the specimen was graded by a blinded pathologist, who also made a pathologic diagnosis. RESULTS: No statistically significant difference was noted in the graded criteria performance plus diagnostic yield between the two techniques. When performed before FNAB, FNCB yielded a better quality specimen of a particular site. However, there was no difference in the graded quality of FNAB whether performed before or after FNCB. Insufficient specimens were obtained at 30 (21.4%) of 140 sites with FNCB versus only 18 (12.8%) with FNAB. CONCLUSION: FNCB is an alternative to FNAB and provides a cellular diagnostic specimen from most lesions. When a coaxial method is used and both techniques are employed, the diagnostic accuracy of these techniques is 84%.

Biopsy, Needle↗
PubMed1995

CT percutaneous biopsy guns: comparison of end-cut and side-notch devices in cadaveric specimens.

OBJECTIVE: The purpose of this study was to compare the efficacies of four different types of end-cut biopsy guns with the side-notch Tru-cut biopsy gun. MATERIALS AND METHODS: A total of 25 liver, 15 kidney, 10 pancreas, and 15 breast biopsies were performed in the tissue from five autopsies with each of 12 different biopsy devices/biopsy depths. The tissue obtained was evaluated by an experienced cytopathologist who, not knowing which gun was used to obtain each specimen, used a predetermined grading scheme. RESULTS: When tissue was obtained, the end-cut biopsy guns performed equivalently to the side-notch biopsy gun in all four tissues. However, the end-cut guns had a significant number of "zero" biopsies (biopsy attempts during which no tissue was obtained). The proportion of zero biopsies with the end-cut guns ranged from up to 28% in the liver to 60% and 73% in the breast and kidney, respectively. CONCLUSION: The end-cut biopsy guns are easy to use and potentially can obtain high-quality specimens. However, the rate of zero biopsies during which no tissue is obtained is a serious deficiency. As a result, the use of the end-cut biopsy gun should be encouraged only for use with an introducer, with which multiple biopsy specimens can easily be obtained without additional needle punctures.

Biopsy, Needle↗