Telethinking: with James A. Brink, M.D. [interview by Vicki Glaser].
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Humans↗
Biomedical subjects
James A Brink
Publications and source records attributed to James A Brink.
Radiation dose associated with unenhanced CT for suspected renal colic: impact of repetitive studies.
OBJECTIVE: The purpose of our study was to assess the dose of ionizing radiation delivered through the use of unenhanced CT for suspected renal colic by determining the incidence of repeated unenhanced CT examinations and the cumulative radiation dose delivered. MATERIALS AND METHODS: All unenhanced CT examinations for suspected renal colic performed at our institution over a 6-year period were included, and patient age, sex, and multiplicity of examinations were determined. For the adult patient, this protocol prescribes a fixed tube current of 200 mA, 140 kVp, and a nominal slice width of 5 mm. The dose-length product (DLP) was estimated for 15 randomly chosen single-detector CT (SDCT) and MDCT adult flank pain examinations using manufacturer's software. The mean DLPs for SDCT and MDCT were computed and converted to effective doses. Total effective doses were calculated for patients who underwent more than three examinations, and values were compared with established standards. RESULTS: A total of 5,564 examinations were performed on 4,562 patients. Of these patients, 2,795 (61%) were women (mean age, 45.5 +/- 16.2 [SD] years) and 1,731 (38%) were men (mean age, 44.7 +/- 16.4 years), with 144 patients (3%) of pediatric age. The mean effective doses for a single study were 6.5 mSv for SDCT and 8.5 mSv for MDCT. A subset of 176 patients (4%) had three or more examinations, with estimated effective doses ranging from 19.5 to 153.7 mSv. All patients with multiple examinations had a known history of nephrolithiasis. CONCLUSION: Patients with a history of nephrolithiasis and flank pain are at increased risk for serial CT with potentially high cumulative effective doses.
Adolescent↗
Regression of coronary atherosclerotic plaque as shown by CT arteriography.
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Coronary Angiography↗
Autoimmune pancreatitis presenting as simultaneous masses in the pancreatic head and gallbladder.
CONTEXT: Autoimmune pancreatitis is a rare variant of chronic pancreatitis characterized by pancreatic ductal narrowing and pancreatic parenchymal edema on computed tomography and rarely with intermittent attacks of abdominal pain. Recently, it has been found to be a systemic disease with lymphoplasmacytic infiltration that has been associated with several autoimmune diseases and described in multiple organs including the extrahepatic bile duct, liver and gallbladder. CASE REPORT: We describe the clinical, radiographic and histopathologic aspects of a patient who presented with synchronous masses in the pancreatic head and gallbladder. Postoperatively, the patient's jaundice subsided and IgG4 levels, which were drawn one week postoperatively, were all within normal limits. Nonetheless, immunohistochemical staining for IgG4 was positive. CONCLUSION: Autoimmune pancreatitis is the most common benign entity identified in patients that underwent pancreaticoduodenectomy for presumed pancreatic adenocarcinoma. Our patient with autoimmune pancreatitis presented with simultaneous inflammatory masses in the gallbladder and pancreatic head, an association not previously reported. Preoperative evaluation of IgG4 or autoantibody levels may have obviated the need for an operation. Therefore, we have begun screening for elevated serum IgG4 concentrations to identify patients with possible autoimmune pancreatitis who present without definitive pathological or radiographic evidence for malignancy. If pre-operative diagnosis is not made, immunohistochemical staining of pathology specimens can confirm the diagnosis.
Acute Disease↗
PET/CT unplugged: the merging technologies of PET and CT imaging.
OBJECTIVE: This article discusses the current and potential issues physicians are facing as PET/CT is integrated into medical practice. CONCLUSION: A variety of issues related to PET/CT were discussed at the 2004 ARRS annual meeting. Among the conclusions were that both PET and CT portions of a PET/CT scan need to be reviewed for adequate patient care, and that nuclear medicine should not be exempt from current self-referral legislation.
Biotechnology↗
Diagnostic CT scans: assessment of patient, physician, and radiologist awareness of radiation dose and possible risks.
PURPOSE: To determine the awareness level concerning radiation dose and possible risks associated with computed tomographic (CT) scans among patients, emergency department (ED) physicians, and radiologists. MATERIALS AND METHODS: Adult patients seen in the ED of a U.S. academic medical center during a 2-week period with mild to moderate abdominopelvic or flank pain and who underwent CT were surveyed after acquisition of the CT scan. Patients were asked whether or not they were informed about the risks, benefits, and radiation dose of the CT scan and if they believed that the scan increased their lifetime cancer risk. Patients were also asked to estimate the radiation dose for the CT scan compared with that for one chest radiograph. ED physicians who requested CT scans and radiologists who reviewed the CT scans were surveyed with similar questions and an additional question regarding the number of years in practice. The chi(2) test of independence was used to compare the three respondent groups regarding perceived increased cancer risk from one abdominopelvic CT scan. RESULTS: Seven percent (five of 76) of patients reported that they were told about risks and benefits of their CT scan, while 22% (10 of 45) of ED physicians reported that they had provided such information. Forty-seven percent (18 of 38) of radiologists believed that there was increased cancer risk, whereas only 9% (four of 45) of ED physicians and 3% (two of 76) of patients believed that there was increased risk (chi(2)(2) = 41.45, P <.001). All patients and most ED physicians and radiologists were unable to accurately estimate the dose for one CT scan compared with that for one chest radiograph. CONCLUSION: Patients are not given information about the risks, benefits, and radiation dose for a CT scan. Patients, ED physicians, and radiologists alike are unable to provide accurate estimates of CT doses regardless of their experience level.
Adolescent↗
The phantom portion of the American College of Radiology (ACR) computed tomography (CT) accreditation program: practical tips, artifact examples, and pitfalls to avoid.
The ACR CT accreditation program, begun in 2002, requires the submission of approximately 20 images, several completed data sheets and printouts of three Excel worksheets. The procedure manual is very detailed, yet participants unfamiliar with the program or having minimal CT experience have needed to redo aspects of their submission, or in some cases do not receive accreditation, due to mistakes made by the physicist. This review of the phantom portion of the ACR CT accreditation program supplements the ACR provided instructions with additional photos of phantom setup, region-of-interest (ROI), and image placement on the film sheets, and examples of completed portions of actual (but anonymous) submissions. Common mistakes, as well as uncommon but interesting images, are shown and explanations are given as to what could have been done to avoid the problem. Additionally, a review of CT dose measurement techniques and calculations will enable the physicist to better assist sites where typical exam doses are above the ACR reference values.
Accreditation↗
Implementation of an international teleradiology staffing model.
Although teleradiology is presently being used extensively in the United States-for both overseas subspecialty consultations and overnight coverage of imaging services at domestic medical centers-there has been limited investigation of its potential to help provide staffing support to U.S. medical centers from offshore locations. In this review, the authors describe an empirical assessment of the clinical feasibility and applicability of body computed tomographic (CT) image cases that originated at a U.S. university hospital being interpreted nearly contemporaneously by a staff radiologist in India. During a 3-month period, nonemergent CT cases obtained at a tertiary care institution (Yale-New Haven Hospital) were transmitted daily to a satellite reading facility in Bangalore, India. The cases were interpreted at the satellite reading facility by a faculty member radiologist who maintained hospital privileges and academic appointment at the parent institution in the United States. CT imaging reports were transcribed and uploaded directly to the parent institution's radiology information system. Technical problems temporarily prevented the transfer of image cases twice during the study period. Overall, the project results demonstrated the feasibility and reliability of an international teleradiology staffing model.
Abdominal Neoplasms↗
Emergency radiology coverage: technical and clinical feasibility of an international teleradiology model.
The purpose of the study was to determine the feasibility of international teleradiology, utilizing day-night time differences, for online interpretation of overnight computed tomography (CT) studies. One hundred and two consecutive Emergency Room patients who underwent CT examinations between the hours of 11 pm and 7 am were enrolled. All age groups and study types were included. CT studies were transmitted from the in-hospital PACS system (Kodak, Fremont, Calif.) to a web-based server (Medweb, San Francisco, Calif.). A radiologist in Bangalore, India, working an 8 amto 4 pm day shift, downloaded and reviewed the studies on a desktop PC using a 128-kbps internet connection at 10-20:1 wavelet compression and generated a report. The report was then uploaded to the server, noting the time at upload. Each study report was compared with the official in-house diagnostic report and concordance assessed on a three-point scale. Mean download time was 8.14 s per image. For head CT reports ( n=47), the mean turnaround time for a final transcribed report was 39.5 min. For abdomen/pelvis CT reports ( n=48) the mean turnaround time was 84.4 min. Out of 106 cases, there was discordance between the clinical diagnostic report and the study report in 20 (19%); however, on subsequent review the teleradiology report was found to be correct in 13 of these. Day-night time differences across the globe can be utilized to provide overnight emergency radiology coverage using web-based teleradiology. Scan download and report upload times are within acceptable limits.
Journal Article↗
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↗
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↗
What multi-detector row CT parameters are best for detection of colon polyps?
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Colon↗
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↗
Enlargement of the inferior vena cava in contrast-enhanced abdominal CT.
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Adult↗
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↗
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↗
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↗