Outpatient Computed Tomography Research Articles

Effect of Computerized Order Entry with Integrated Decision Support on the Growth of Outpatient Procedure Volumes: Seven-year Time Series Analysis

To determine the effect of a computerized radiology order entry (ROE) and decision support (DS) system on growth rate of outpatient computed tomography (CT), magnetic resonance (MR) imaging, and ultrasonography (US) procedure volumes over time at a large metropolitan academic medical center. Institutional review board approval was obtained for this study of deidentified aggregate administrative data. The research was compliant with HIPAA; informed consent was waived. This was a retrospective study of outpatient advanced imaging utilization before, during, and after implementation of a Web-based ROE and DS system. Dependent variables were the quarterly volumes of outpatient CT, MR imaging, and US examinations from quarter 4 of 2000 through quarter 4 of 2007. Outpatient visits during each quarter were included as control variables. These data were analyzed as three separate time series with piecewise linear regression for simultaneous estimation of quarterly examination volume trends before and after ROE and DS system implementation. This procedure was repeated with log-transformed quarterly volumes to estimate percentage growth rates. There was a significant decrease in CT volume growth (274 per quarter) and growth rate (2.75% per quarter) after ROE and DS system implementation (P < .001). For MR imaging, growth rate decreased significantly (1.2%, P = .016) after ROE and DS system implementation; however, there was no significant change in quarterly volume growth. With US, quarterly volume growth (n = 98, P = .014) and growth rate (1.3%, P = .001) decreased significantly after ROE implementation. These changes occurred during a steady growth in clinic visit volumes in the associated referral practices. Substantial decreases in the growth of outpatient CT and US procedure volume coincident with ROE implementation (supplemented by DS for CT) were observed. The utilization of outpatient MR imaging decreased less impressively, with only the rate of growth being significantly lower after interventions were in effect.

Maximizing Outpatient Computed Tomography Productivity Using Multiple Technologists

A key radiology stakeholder demand is to increase patient access to computed tomography (CT) and reduce waiting lists. However, the number of patients that a single technologist can scan is limited because of the many tasks required to process a patient through a CT scan. However, many tasks could be performed simultaneously by using additional personnel. This study evaluated how many additional patients can be scanned using a 2- or 3-technologist model with outpatient multidetector CT and its impact on CT capacity. The number and type of individual technologist tasks were initially evaluated. The time to perform these tasks was then measured using 1-, 2-, and 3-technologist models, including the time a patient was within the CT scanner room, to determine the hourly patient throughput on a CT scanner. Two theoretic CT operations were then developed to evaluate the impact on CT capacity. Thirty-four technologist workflow tasks were identified. A total of 205 outpatients were evaluated. The total time to perform all tasks for 1-, 2-, and 3-technologist models was 27, 23, and 22 minutes, respectively. CT room time per patient for 1-, 2-, and 3-technologist models was 12, 9.7, and 8.0 minutes, respectively. However, the number of patients scanned per hour for 1-, 2-, and 3-technologist models was 2.2, 5.2, and 7.5, respectively. There was an increase of more than 12,000 potential patient CT slots made available using 2 technologists 7 days per week and 22,000 additional slots for a 3-technologist model when compared with a single-technologist model on weekdays only. A single-technologist model for outpatient multidetector CT is inefficient with limited opportunity for increased patient throughput. The use of multiple technologists (or other key personnel) optimizes CT throughput and capacity, particularly with a 3-technologist model, which can yield a greater than three-fold increase in CT productivity.

Low-attenuation oral GI contrast agents in abdominal-pelvic computed tomography

We designed and evaluated a low-attenuation oral contrast agent for abdominal-pelvic computed tomography (CT). In vitro studies, were performed initially to evaluate the imaging characteristics of multiple solutions. These studies resulted in two solutions being compared with the presently accepted oral CT agents of dilute iodinated contrast and water. Ninety-eight consecutive subjects already scheduled for routine outpatient abdominal-pelvic CT were enrolled. Subjects were randomized to water (n = 30), fiber solution (n = 32), polyethylene glycol (PEG; n = 11), or dilute iodinated solution (DI; n = 25). Examinations were then evaluated for gastric distention, small bowel distention, small bowel wall visualization, and colonic transit. A questionnaire was given to the study subjects for feedback concerning taste and potential side effects from these agents. PEG tended to provide better bowel distention, wall visualization, and colonic transit compared with water, fiber solution, and DI. Areas of statistical significance included: (1) average bowel diameter in the left upper quadrant for water was 17.50 mm, whereas that for PEG was 21.88 mm (p < 0.05); (2) average bowel diameter in the pelvis for water was 14.79 mm, that for fiber was 15.67 mm, and that for PEG was 18.48 mm (p < 0.05); (3) wall visualization was better with PEG than with fiber (p < 0.05); (4) successful transit of contrast to the colon occurred in every subject who received PEG compared with only 20% of those received water and 39% of those who received fiber (p < 0.05). Similar trends for the superiority of PEG over DI were noted, although many of these did not reach statistical significance. PEG solution has imaging characteristics related to bowel wall visualization, luminal distention, and colonic transit that make it an effective oral agent for abdominal pelvic CT examination.

Are Screening Serum Creatinine Levels Necessary prior to Outpatient CT Examinations?

To determine the percentage of outpatients with elevated serum creatinine levels (>/=2.0 mg/dL [177 micromol/L]) and associated reported risk factors for contrast material-induced nephrotoxic reactions (eg, diabetes, renal disease, male, age >/= 60 years, chemotherapy) who undergo computed tomography (CT) and to define a true high-risk population. The serum creatinine levels were obtained in a total of 2,034 consecutive outpatients (969 male, 1,065 female) who underwent contrast material-enhanced CT. In addition, selected patient charts were reviewed to determine the presence of risk factors for contrast material-induced nephrotoxic reactions. Only 66 (3.2%) had an elevated serum creatinine level. Risk factors were identified in 64 of the 66 (97%) patients with an elevated serum creatinine level. Renal disease was present in 62 of the 66 (94%) patients. Two of the 66 patients with an elevated creatinine level had no identifiable risk factors, representing 0.1% of the total number of patients. The data suggest that the majority of patients with a serum creatinine level of at least 2.0 mg/dL (177 micromol/L) will be identified by screening for risk factors. Careful patient screening, especially for renal disease, at the time of scheduling could result in considerable savings in terms of radiology man-hours expended and laboratory costs.