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James A Brink

Publications and source records attributed to James A Brink.

8 recordsLinked to original sources
PubMed2003

Computerized tomographic colonography: performance evaluation in a retrospective multicenter setting.

BACKGROUND & AIMS: No multicenter study has been reported evaluating the performance and interobserver variability of computerized tomographic colonography. The aim of this study was to assess the accuracy of computerized tomographic colonography for detecting clinically important colorectal neoplasia (polyps >or=10 mm in diameter) in a multi-institutional study. METHODS: A retrospective study was developed from 341 patients who had computerized tomographic colonography and colonoscopy among 8 medical centers. Colonoscopy and pathology reports provided the standard. A random sample of 117 patients, stratified by criterion standard, was requested. Ninety-three patients were included (47% with polyps >or=10 mm; mean age, 62 years; 56% men; 84% white; 40% reported colorectal symptoms; 74% at increased risk for colorectal cancer). Eighteen radiologists blinded to the criterion standard interpreted computerized tomography colonography examinations, each using 2 of 3 different software display platforms. RESULTS: The average area under the receiver operating characteristic curve for identifying patients with at least 1 lesion >or=10 mm was 0.80 (95% lower confidence bound, 0.74). The average sensitivity and specificity were 75% (95% lower confidence bound, 68%) and 73% (95% lower confidence bound, 66%), respectively. Per-polyp sensitivity was 75%. A trend was observed for better performance with more observer experience. There was no difference in performance across software display platforms. CONCLUSIONS: Computerized tomographic colonography performance compared favorably with reported performance of fecal occult blood testing, flexible sigmoidoscopy, and barium enema. A prospective study evaluating the performance of computerized tomography colonography in a screening population is indicated.

Colonic Neoplasms↗
PubMed2003

Use of high concentration contrast media (HCCM): principles and rationale--body CT.

Numerous complex pharmacokinetic interrelationships affect the use of contrast media for computed tomography (CT) imaging. The volume, concentration, and rate of injection, all affect the degree of enhancement that is achieved with an injection of contrast material. In addition, the injection technique, whether the contrast is infused with a constant injection rate (uniphasic injection) or whether the rate is altered during the injection (multiphasic injection) also affect the magnitude and duration of contrast enhancement. In body CT imaging, the liver poses unique challenges in managing the use of intravenous contrast material because of its dual blood supply and the need to complete imaging before equilibrium occurs between the intravascular and extravascular compartments. The magnitude of hepatic enhancement that is ultimately achieved is related primarily to the amount of iodinated contrast material that accumulates in the extravascular space within the target organ, independent of the speed of the CT scanner. The key determinant of the onset of the equilibrium phase is the injection duration. Given that a high injection flow rate (4-5 ml/s) is desirable for arterial phase imaging, the injection duration is maintained with use of an appropriate contrast volume. Thus, modifications of total iodine dose are best done with alterations in contrast concentration. The magnitude of arterial enhancement that is achieved is related to both the concentration and rate of contrast administration. The speed of the scanner determines its ability to record image data during the most advantageous time period, the peak of arterial enhancement. Thus, rapid imaging is particularly advantageous for optimal contrast use in CT angiography as well as in multiphasic imaging of the parenchymal organs.

Angiography↗
PubMed2003

Detection of colorectal lesions: lower-dose multi-detector row helical CT colonography compared with conventional colonoscopy.

PURPOSE: To compare the performance of lower-dose multi-detector row helical computed tomographic (CT) colonography with that of conventional colonoscopy in the detection of colorectal lesions. MATERIALS AND METHODS: One hundred fifty-eight patients underwent multi-detector row helical CT colonography (beam collimation, 4 x 2.5 mm; table feed, 17.5 mm/sec; voltage, 140 kV; and effective dose, 10 mAs) followed by conventional colonoscopy. Conventional colonoscopy served as the reference standard. Two radiologists interpreted CT colonographic images to assess the presence of polyps or carcinomas. Sensitivity was calculated on both a per-polyp and a per-patient basis. In the latter, specificity and positive and negative predictive values were also calculated. Weighted CT dose index was calculated on the basis of measurements obtained in a standard body phantom. Effective dose was estimated by using commercially available software. RESULTS: CT colonography correctly depicted all 22 carcinomas (sensitivity, 100%) and 52 of 74 polyps (sensitivity, 70.3%). Sensitivity for detection was 100% in all 13 polyps 10 mm or larger in diameter, 83.3% in 20 of 24 polyps 6-9 mm, and 51.3% in 19 of 37 lesions 5 mm or smaller. With regard to the per-patient analysis, CT colonography had a sensitivity of 96.0%, a specificity of 96.6%, a positive predictive value of 94.1%, and a negative predictive value of 97.7%. The total weighted CT dose index for combined prone and supine acquisitions was 2.74 mGy. The simulated effective doses for complete CT colonography were 1.8 mSv in men and 2.4 mSv in women. CONCLUSION: Lower-dose multi-detector row helical CT colonography ensures substantial dose reduction while maintaining excellent sensitivity for detection of colorectal carcinomas and polyps larger than 6 mm in diameter.

Aged↗
PubMed2002

Evaluation of an emergency radiology quality assurance program at a level I trauma center: abdominal and pelvic CT studies.

PURPOSE: To evaluate the use of a redundant system in improving quality of care in the trauma setting by examining a subset of our quality assurance program. MATERIALS AND METHODS: Five hundred thirty-one consecutive abdominal and pelvic CT reports obtained in patients with trauma at a level I trauma center from August 22, 1999, to August 21, 2000, were retrospectively reviewed. Each case was initially interpreted by a board-certified or board-eligible radiologist during evaluation in the emergency department and was subsequently reviewed by a subspecialty abdominal imaging radiologist as part of a quality assurance program. Nineteen cases were excluded because available information was incomplete, resulting in 512 cases in the current study. Cases with discordant interpretations were followed up to discern care change. RESULTS: Of the 512 trauma cases, 153 (29.9%) showed discordant readings. Review of patient records demonstrated changes in patient care in 12 (7.8%) cases. Three (2.0%) cases were reviewed from the morbidity and mortality records of the Department of Trauma Surgery as a direct result of misinterpretations. Six (4%) cases involved additional diagnostic imaging for reevaluation; in four of these six cases the quality assurance reader's interpretation was confirmed, while in the other two, the initial interpretations were favored. CONCLUSION: Findings suggest that discordant radiologic interpretations most often do not result in a change in patient care and outcome. The quality assurance program did, however, identify and lead to changes in care in a number of cases by providing clinically important additional findings.

Adolescent↗
PubMed2002

CT colonography: multiobserver diagnostic performance.

PURPOSE: To prospectively evaluate multiobserver diagnostic performance and reader agreement for colorectal polyp detection in a well-characterized cohort of patients with increased number of polyps, compared with an average-risk patient, with colonoscopy as the reference standard. MATERIALS AND METHODS: A cohort of 70 patients suspected of having polyps was examined with spiral computed tomographic (CT) colonography, with colonoscopy performed the same day. After air insufflation per rectum, supine and prone images were obtained with single-detector row CT (5-mm collimation, 8-mm table increment, 2-mm reconstruction interval). Images were analyzed independently by four experienced abdominal radiologists using two-dimensional multiplanar reformation followed by selective use of three-dimensional endoscopic volume-rendered images. Data were analyzed both per polyp and per patient. RESULTS: Analysis per polyp demonstrated a pooled sensitivity of 0.68 for lesions 10 mm or larger (n = 40), with 75% agreement among the four readers. Analysis per patient demonstrated improved detection and agreement, with a pooled sensitivity of 0.88 for patients with polyps or cancers 10 mm or larger (n = 28), with 94% agreement. When sensitivity and receiver operating characteristic analyses were analyzed per polyp size threshold, results among readers converged and peaked at polyp diameters of approximately 10 mm. CONCLUSION: In this patient cohort, diagnostic performance and interobserver agreement with single-detector row CT colonography was sufficient for detection of patients with lesions 10 mm or larger, with more variable results for smaller polyps.

Adult↗
PubMedDate not supplied

Contrast optimization and scan timing for single and multidetector-row computed tomography.

Various complex pharmacokinetic interrelationships affect the use of contrast media for computed tomography (CT) imaging. These include factors related to each patient's unique body habitus and their degree of health, such as their age, gender, height, weight, and cardiovascular status. Of equal importance are factors related to the contrast material injection. The volume, concentration, and rate of injection all affect the degree of enhancement that is achieved with an injection of contrast material. In addition, the injection technique--whether the contrast is infused at a constant injection rate (uniphasic injection) or whether the rate is altered during the injection (multiphasic injection)--also affects the magnitude and duration of contrast enhancement. In body CT imaging, the liver poses unique challenges in managing the use of intravenous contrast material because of its dual blood supply and the need to complete imaging before equilibrium occurs between the intravascular and extravascular compartments. The magnitude of hepatic enhancement that is ultimately achieved is related primarily to the amount of iodinated contrast material that accumulates in the extravascular space within the target organ, independent of the speed of the CT scanner. The key determinant of the onset of the equilibrium phase is the injection duration. Given that a high injection flow rate (4-5 ml/s) is desirable for arterial phase imaging, the injection duration is maintained by using an appropriate contrast volume. Thus, modifications of the total iodine dose are best performed by altering the contrast concentration. Use of a high contrast concentration (400 mg iodine/ml) may be advantageous in heavy patients, or in patients in whom routine imaging is married with a need for high-detail imaging of the vasculature with high resolution CT angiography. The magnitude of arterial enhancement that is achieved is related to both the concentration of contrast and the rate of administration. The speed of the scanner determines its ability to record image data during the most advantageous time period, the peak of arterial enhancement. Thus, rapid imaging is particularly advantageous for optimal contrast use in CT angiography as well as in multiphasic imaging of the parenchymal organs.

Body Weight↗