Search PubMed⌕ Search

Biomedical subjects

K D Hopper

Publications and source records attributed to K D Hopper.

At least 55 records · Page 3Linked to original sources
PubMed1995

Percutaneous biopsy of the liver and kidney by using coaxial technique: adequacy of the specimen obtained with three different needles in vitro.

OBJECTIVE: The coaxial biopsy technique was evaluated with respect to the quality of specimens obtained from the liver and kidneys in vitro on sequential biopsies at the same site with each of three different biopsy needles. MATERIALS AND METHODS: For each of three different biopsy needles (aspiration 18-gauge Chiba, 18-gauge Sure-Cut, and 18-gauge Biopty), 30 sites (15 liver, 15 kidney) were selected for in vitro coaxial biopsy. At each site, an introducer was placed, through which three sequential biopsies were done. Blinded histopathologic analysis was used to grade the quality of specimens on a scale from 0 (no tissue) to 3 (best) for three criteria: adequacy of tissue for diagnosis, tissue fragmentation, and crush artifact. The overall score was the sum of the scores for the three individual criteria and ranged from 0 (no tissue) to 9 (best). RESULTS: Using an 18-gauge Chiba needle and coaxial technique, we found no significant reduction in specimen quality when we did multiple aspiration biopsies at the same site. However, no tissue was obtained (zero biopsy) from a large number of aspiration biopsies done with the Chiba needle, ranging from 24 of 30 for the first biopsy to 17 of 30 for the third biopsy. Specimen quality was reduced somewhat between the first and third biopsies when the 18-gauge Sure-Cut and Biopty needles were used. With the Sure-Cut needle, this reduction in quality was significant (p = .009) and was primarily related to increased tissue fragmentation and crushing. The reduction in quality with multiple biopsy attempts was less severe with the Biopty needle/gun. Although the mean score decreased from 6.6 for the first biopsy to 5.5 for the third biopsy, this reduction was not significant (p = .06). In addition, the Biopty gun, unlike the other two needles, had few zero biopsies. CONCLUSION: The use of a coaxial technique with an 18-gauge Biopty needle enables collection of a large amount of high-quality tissue for histopathologic analysis with a minimum number of failed biopsies as compared with the 18-gauge Chiba needle and the 18-gauge Sure-Cut needle.

Biopsy, Needle↗
PubMed1995

Informed consent forms for clinical and research imaging procedures: how much do patients understand?

OBJECTIVE: Informed consent is often obtained in diagnostic radiology, especially for invasive procedures and research studies. However, how much the average patient actually understands of the information contained in these informed consent forms is uncertain. A cross section of the clinical and research consent forms used in diagnostic radiology was evaluated with respect to their readability, that is, how easy or difficult they were to understand. MATERIALS AND METHODS: The active members of the Association of University Radiologists were solicited to provide copies of their clinical and research informed consent forms. After eliminating duplicates, we digitized the forms and used a computer program to evaluate their readability. Computer readability assessment allows the rapid study of an entire document by a variety of readability formulas (Flesch-Kincaid, Flesch, and Fog). RESULTS: We received 549 different consent forms from 156 institutions; 265 forms were intended primarily for clinical use and 284 were used primarily for research. Although the clinical consent forms were only 41% as long as those for research, a statistical comparison showed them to be harder to understand (p < 0.005). The mean readability score (years of education needed to understand) for all 265 clinical consent forms was 15 versus 12 for the research forms. The most complex clinical consent forms were those written by hospitals for any type of procedure or operation (the generic surgical or procedure consent form). On average, this type of clinical consent form required at least a college education to understand. CONCLUSION: Our results show that most consent forms used in radiology practice are too complex for the average patient to understand. The increased complexity of clinical consent forms, especially the generic surgical or procedure consent forms, as compared with research consent forms, is probably a product of the decreased attention given to the clinical consent forms, the bureaucratic and legal requirements of the clinical forms, and the lack of physician participation in preparing these forms.

Cognition↗
PubMed1995

Reconstructed helical CT scans: improvement in z-axis resolution compared with overlapped and nonoverlapped conventional CT scans.

OBJECTIVE: This in vitro study was designed to assess the z-axis resolving capabilities of reconstructed helical CT scans obtained with various imaging parameters versus those of conventional CT scans and the effect of decreasing slice index on the z-axis resolution of helical CT. MATERIALS AND METHODS: A z-axis line-pair phantom was imaged using conventional nonoverlapped CT scans, conventional CT scans that overlapped by 50%, and helical CT scans with pitches of 1.0 and 1.5. All helical images were reconstructed at comparable slice indexes (image indexes of 2.0, 1.0, and 0.5 mm for pitch = 1.0, and image indexes of 3.0, 1.5, and 0.75 mm for pitch = 1.5). Midline coronal and sagittal reconstructed images were obtained to allow standardized visualization of line pairs. The reconstructed images were reviewed separately by 10 radiologists. RESULTS: The overall z-axis resolution of reconstructed helical CT scans equaled or exceeded that of nonoverlapped conventional CT scans in all cases and equaled that of 50% overlapped conventional CT scans in 75% of cases. The 1.0-pitch helical sequences showed improved z-axis resolution with decreasing slice index. No statistically significant improvement in z-axis resolution could be determined by the observers for 1.5-pitch sequences with decreasing slice index. CONCLUSION: The use of helical CT with a pitch of 1.0 or 1.5 and an increased slice index can improve the z-axis resolution of reconstructed images when compared with nonoverlapped conventional CT and frequently equals the resolution of 50% overlapped conventional CT. This improvement in z-axis resolution should improve the appearance of reconstructed images (as used in CT angiography and three-dimensional imaging) by reducing partial volume artifacts while affording faster scanning at a reduced skin-surface radiation dose.

Humans↗
PubMed1995

95th anniversary of the ARRS: history of the Journal editors. American Roentgen Ray Society.

The change of AJR editorship with next month's issue and the celebration of the centennial year of the X-ray make this an appropriate time to acknowledge the many distinguished editors who have served the American Roentgen Ray Society. A review of these gentlemen's service to this Journal is in no small measure a chronology of the Society's history itself, especially during its first turbulent decade. The recounting of this story should entertain and educate as well as pay tribute to these fine scholars. Perhaps most of all, it should cause us all to reflect upon the tremendous sacrifices made for radiology in the United States and for our Society by these individuals.

History, 20th Century↗
PubMed1994

The relationship of age, gender, handedness, and sidedness to the size of the corpus callosum.

OBJECTIVES: We correlated the area and size of the corpus callosum, as measured by MR imaging, with the individual's handedness, sidedness, age, and gender. MATERIALS AND METHODS: A total of 117 patients (59 male, 58 female) aged 15-75 years were selected for this study. This included 12 persons who were either left-handed or ambidextrous. Each patient was tested extensively to determine handedness and sidedness. Callosal areas and thickness were measured and correlated with brain size. RESULTS: The body of the corpus callosum decreases in size with age and is larger in right-handed persons. The cross-sectional areas of the genu, splenium, and corpus callosum, overall, do not vary significantly with respect to age, gender, sidedness, or handedness. CONCLUSIONS: The size of the corpus callosum consistently decreases with age. Otherwise, few statistical differences in callosal size relate to gender, sidedness, or handedness.

Adolescent↗
PubMed1994

Interactive method of informing patients of the risks of intravenous contrast media.

PURPOSE: To evaluate interactive computer-based informed consent for use of contrast material versus the same information in a written format. MATERIALS AND METHODS: Patients (n = 160) referred for radiologic examination with intravenous contrast material were block randomized (sex, age, and previous exposure to contrast material) into two groups and were provided either written or computer-based (video) informed consent. RESULTS: The female patients in the video group scored better on the test than those in the group with the written consent form. Male patients attained equivalent scores with both types of consent. The video took an average of 1.6 minutes longer to complete, probably because the majority of patients chose to be informed of every risk of intravenous contrast material. CONCLUSION: This project demonstrates that a video format for informed consent before use of intravenous contrast material offers a good alternative to the written consent form.

Comprehension↗
PubMed1994

Risks associated with the use of IV contrast material: analysis of patients' awareness.

OBJECTIVE: Opinions differ on the need to obtain informed consent for IV administration of contrast material. If the potential risks are common knowledge among most patients, the need for informed consent is reduced. The purpose of this study was to assess patients' baseline knowledge of the risks associated with use of IV contrast material. SUBJECTS AND METHODS: This study included 150 consecutive outpatients who had radiographic studies (CT or excretory urography) requiring use of IV contrast material. Before the procedure, patients were asked to complete a 10-question questionnaire assessing their understanding of the risks associated with the use of contrast material. Questions concerned the nature of their test and the reasons for and risks of contrast material. Analysis was done with Fisher's exact chi 2-test of association and Wilcoxon's two-sample test. RESULTS: On average, the patients performed significantly better on this questionnaire than if they had randomly picked each answer, indicating that the average patient has acquired some information about IV contrast material. However, the mean score was 51%, demonstrating that the average patient is not knowledgeable about all risks associated with the use of IV contrast material. We found no differences associated with sex or age. Patients with more than a high school level of education and who had previously received contrast material scored better, although they still correctly answered only 56% and 54% of the questions, respectively. CONCLUSION: Information about the risks associated with use of IV contrast material cannot be considered common knowledge among the general population of patients.

Aged↗
PubMed1994

The effect of informed consent on the level of anxiety in patients given i.v. contrast material.

OBJECTIVE: A common reason given for not obtaining informed consent before the use of IV contrast material is that the anxiety created by informing patients of potential reactions will increase the possibility of their occurring. However, the idea that this is possible is debatable, and no study of this subject has used a standardized anxiety index. Accordingly, using the State-Trait Anxiety Inventory, we assessed the anxiety level among patients about to have an IV contrast procedure and measured the effect of informing them of the risks associated with the use of contrast material. SUBJECTS AND METHODS: Approximately 2050 adult outpatients at three separate medical centers were solicited for participation in this study. Each of the 1251 patients who volunteered to participate was placed into one of six groups. The majority were patients who were awaiting the injection of either ionic or nonionic contrast material and who were or were not informed of the risks associated with the use of IV contrast material. The last two groups were generally healthy outpatients reporting for routine X-rays who were not awaiting IV contrast administration but who were informed of the risks associated with the use of ionic and nonionic contrast material. Each patient informed of the risks was asked to read a standardized consent form, and all patients completed a standardized anxiety index. RESULTS: Patients who were informed of the risks associated with IV contrast material did not have measurably increased anxiety, and they did not have an increased prevalence of adverse reactions. Indeed, the only patients who had statistically significant increased anxiety compared with the other groups were among those awaiting the injection of ionic contrast material who were not informed of the risks (p = .04). The majority (51-78%) of patients in all six groups had measurable elevated anxiety scores. CONCLUSION: We conclude that it is not justified to fail to obtain informed consent in order to avoid anxiety-induced adverse reactions to IV contrast material. The majority of patients awaiting injection of IV contrast material have measurable increased anxiety levels regardless of whether they are informed of its risks.

Anxiety↗
PubMed1994

Imaging variants of the liver, pancreas, and spleen.

The liver, spleen, and pancreas are three of the most frequently imaged intra-abdominal organs. Each organ is a complex structure affected by multiple pathologic processes. However, in order to recognize the pathologic changes that affect each organ, one must have a detailed knowledge of the broad spectrum of normal variants that can be seen when imaging the upper abdomen. This review explores the wide variability in appearance of the normal liver, spleen, and pancreas during cross-sectional imaging (CT, US, and MRI), stressing a thorough understanding of normal anatomy and the affect of physiologic variants.

Adult↗
PubMed1993

The papillary process: a pseudotumor on coronal and sagittal MRI.

The papillary process of the caudate lobe can extend posteriorly to lie between the inferior vena cava (IVC) and aorta. Occasionally, the papillary process can wrap around the IVC such that its tip lies posterior to the inferior vena cava. These positions of the papillary process create the potential for its misdiagnosis as a lymph node or mass on coronal and sagittal MRI. To evaluate the frequency that this variant occurs, we retrospectively evaluated contrast axial CT scans in 113 adult patients. Ninety-seven percent had a portion of their papillary process extending posterior to the anterior margin of the IVC. In 66% of the patients, the papillary process overlapped more than 50% of the IVC. In these patients, the papillary process would likely appear as a separate soft tissue structure between the IVC and aorta on coronal MRI. In 12 patients, the papillary process not only extended posterior to lie between the IVC and aorta, but actually extended behind a portion of the inferior vena cava as well. This position of the papillary process could appear as a separate soft tissue structure between the IVC and the diaphragmatic crus on sagittal MRI. The posterior extent of the papillary process between the inferior vena cava and aorta, and occasionally, behind the inferior vena cava, are common anatomical variants, knowledge of which may prevent misdiagnosis on coronal and sagittal MRI.

Abdomen↗
PubMed1993

Transmural thoracic lipoma: CT and MRI features.

Lipomas are common benign neoplasms of the chest wall. However, their extension from the pleural space through the ribs into the superficial tissues of the chest wall has been described only twice previously, both by computed tomography (CT). A case is presented of a transmural chest wall lipoma diagnosed by MRI with CT correlation. The advantages of MRI in the diagnosis of these unique neoplasms are described.

Aged↗