CT screening: why I do it

Radiation and iodine dose reduced thoraco-abdomino-pelvic dual-energy CT at 40 keV reconstructed with deep learning image reconstruction

OBJECTIVE

To evaluate the feasibility of a simultaneous reduction of radiation and iodine doses in dual-energy thoraco-abdomino-pelvic CT reconstructed with deep learning image reconstruction (DLIR).

METHODS

Thoraco-abdomino-pelvic CT was prospectively performed in 111 participants; 52 participants underwent a standard-dose single-energy CT with a standard iodine dose (600 mgI/kg; SD group), while 59 underwent a low-dose dual-energy CT with a reduced iodine dose [300 mgI/kg; double low-dose (DLD) group]. CT data were reconstructed with a hybrid iterative reconstruction in the SD group and a high-strength level of DLIR at 40 keV in the DLD group. Two radiologists measured the CT numbers of the descending and abdominal aorta, portal vein, hepatic vein, inferior vena cava, liver, pancreas, spleen, and kidney, and background noise. Two other radiologists assessed diagnostic acceptability using a 5-point scale. The CT dose-index volume (CTDIvol), iodine weight, CT numbers of anatomical structures, background noise, and diagnostic acceptability were compared between the two groups using Mann-Whitney U test.

RESULTS

The median CTDIvol [10 mGy; interquartile range (IQR), 9-13 mGy vs 4 mGy; IQR, 4-5 mGy] and median iodine weight (35 g; IQR, 31-38 g vs 16 g; IQR, 14-18 g) were lower in the DLD group than in the SD group (p < 0.001 for each). The CT numbers of all anatomical structures and background noise were higher in the DLD group than in the SD group (p < 0.001 for all). The diagnostic image quality was obtained in 100% (52/52) of participants in the SD group and 95% (56/59) of participants in the DLD group.

CONCLUSION

Virtual monochromatic images at 40 keV reconstructed with DLIR could achieve half doses of radiation and iodine while maintaining diagnostic image quality.

ADVANCES IN KNOWLEDGE

Virtual monochromatic images at 40 keV reconstructed with DLIR algorithm allowed to reduce the doses of radiation and iodine while maintaining diagnostic image quality.

Whole-body computed tomography: a new point of view in a hospital check-up unit? Our experience in 6516 patients

BACKGROUND

There is a growing awareness that prevention and early diagnosis may reduce the high mortality associated with cancer, cardiovascular and other diseases. The role of whole-body computed tomography (WB-CT) in self-referred and asymptomatic patients has been debated.

AIM

To determine frequency and spectrum of WB-CT findings in average-risk subjects derived from a Medical-Check-Up-Unit, to evaluate recommendations reported and distribution according to sex and age-groups.

MATERIALS AND METHODS

We retrospectively reviewed 6516 subjects who underwent WB-CT (June 2004/February 2015). All were > 40 years and referred by Medical-Check-Up-Unit of our hospital. The main findings were categorized and classified as normal or not. Its distribution according to sex and age-groups was evaluated using Chi-square test and linear-by-linear association test, respectively. Number of recommendations, type and interval of follow-up were recorded. Descriptive statistics were used.

RESULTS

WB-CT performed in 6516 patients (69% men, 31% women, mean age = 58.4 years) revealed chest (81.4%), abdominal (93.06%) and spine (65.39%) abnormalities. Only 1.60% had completely normal exploration. Abnormal WB-CT in men was significantly higher than women (98.64% vs. 97.87%; p = 0.021), with significant increase as age was higher (40-49 years: 95.65%; 50-59 years: 98.33%; 60-69 years: 99.47%; > 69 years: 99.89%) (p < 0.001). Although most findings were benign, we detected 1.47% primary tumors (96, mainly 35 kidneys and 15 lungs). 17.39% of patients received at least one recommendation predominantly in chest (78.19%) and follow-up imaging (69.89%).

CONCLUSION

The most common WB-CT findings in asymptomatic subjects are benign. However, this examination allows identifying an important number of relevant and precocious findings that significantly increase with age, involving changes in lifestyle and precocious treatment.

Ethical problems in radiology: radiological consumerism

One of the causes of the increasing request for radiological examinations occurring in all economically developed countries is the active role played by the patient-consumer. Consumerism places the radiologist in an ethical dilemma, between the principle of autonomy on the one hand and the ethical principles of beneficence, nonmaleficence and justice on the other. The choice made by radiologists in moral dilemmas is inspired by an adherence to moral principles, which in Italy and elsewhere refer to the Judaeo-Christian tradition or to neo-Darwinian relativism. Whatever the choice, the radiologist is bound to adhere to that choice and to provide the patient with all the relevant information regarding his or her state of health.

Impact of whole-body CT screening on the cost-effectiveness of CT colonography

PURPOSE

To analyze the impact of adding computed tomographic (CT) imaging of the chest on the clinical effectiveness and cost-effectiveness of CT colonography to determine whether performing CT colonography and whole-body CT is a more clinically and cost-effective strategy than CT colonography alone when screening average-risk subjects.

MATERIALS AND METHODS

A Markov model simulated the occurrence of colorectal neoplasia, extracolonic abominal-pelvic malignancy, lung cancer, coronary artery disease (CAD), and abdominal aortic aneurysm (AAA) in a cohort of 100,000 U.S. subjects aged 50 to 100 years. Cost-effectiveness of CT colonography and whole-body CT was compared with that of CT colonography alone; each test was assumed to be repeated every 10 years between ages of 50 and 80 years.

RESULTS

Performing CT colonography and whole-body CT was more effective and costly than was CT colonography alone. The addition of chest CT was associated with a 22% increase in efficacy (life-years gained: 14,662 vs 11,990) and with a 48% increase in cost per person ($13,605 vs $9,223). Both strategies were cost effective as compared with no screening, with an incremental cost-effectiveness ratio (ICER) of $17,672 (CT colonography alone) and $44,337 (CT colonography and whole-body CT), respectively, but performing CT colonography and whole-body CT was not a cost-effective option when compared with CT colonography alone (ICER, $164,020). This was mainly a result of the high cost of false-positive follow-up for CAD and to the poor efficacy of lung cancer screening. Expected value of perfect information was $520 per patient.

CONCLUSION

The addition of chest CT to CT colonography does not appear to be a cost-effective alternative. Further research is needed before whole-body CT can be recommended in clinical practice.

Screening in the dark: ethical considerations of providing screening tests to individuals when evidence is insufficient to support screening populations

During the past decade, screening tests using computed tomography (CT) have disseminated into practice and been marketed to patients despite neither conclusive evidence nor professional agreement about their efficacy and cost-effectiveness at the population level. This phenomenon raises questions about physicians' professional roles and responsibilities within the setting of medical innovation, as well as the appropriate scope of patient autonomy and access to unproven screening technology. This article explores how physicians ought to respond when new screening examinations that lack conclusive evidence of overall population benefit emerge in the marketplace and are requested by individual patients. To this end, the article considers the nature of evidence and how it influences decision-making for screening at both the public policy and individual patient levels. We distinguish medical and ethical differences between screening recommended for a population and screening considered on an individual patient basis. Finally, we discuss specific cases to explore how evidence, patient risk factors and preferences, and physician judgment ought to balance when making individual patient screening decisions.

The use of CT for screening: a national survey of radiologists' activities and attitudes

PURPOSE

To investigate the activities, motivations, and attitudes of radiologists regarding specific computed tomographic (CT) screening examinations by using a survey.

MATERIALS AND METHODS

All study activities were approved by the institutional review board. A self-administered, mailed survey was used to collect data on the practices and attitudes of U.S. radiologists regarding three CT screening tests--coronary artery calcium scoring (CACS), lung cancer screening CT, and whole-body screening CT. The survey was sent to 1000 diagnostic radiologists who were randomly sampled from the American Medical Association Physician Masterfile.

RESULTS

A total of 398 (41.4%) of 961 eligible radiologists completed the survey. Among respondents, 33.6% reported reading CT screening studies, the most common being CACS (26.7%), followed by lung screening (19.2%) and whole-body screening (9.5%). Among respondents, 34.1% supported CACS and 29.9% supported lung CT screening for particular patients, while 1.9% supported whole-body CT screening. The most common reasons reported for reading CT screening studies were responses to requests from physicians (83.3%) or patients (75.0%), while fewer (40.8%) cited patient benefit from screening as a reason.

CONCLUSION

A substantial proportion of a nationally representative sample of radiologists in the United States reads CT screening studies of the heart, lungs, and whole body and holds favorable attitudes toward CACS and lung CT screening. These attitudes may allow for the premature diffusion of new screening tests into practice before higher-level evidence demonstrates their benefits for population mortality.

Total-body screening: preliminary results of a pilot randomized controlled trial

PURPOSE

The authors performed a pilot randomized controlled trial of total-body screening to assess the feasibility of a full-scale study.

MATERIALS AND METHODS

After informed consent, 50 asymptomatic people were randomized to either the intervention arm (total-body screening with multidetector computed tomography) or the control arm (no screening for 3 years). The study was approved by our institutional review board and was compliant with the Health Insurance Portability and Accountability Act. Images were interpreted independently by 6 radiologists from 2 institutions. Subjects in both study arms completed periodic health questionnaires and medical utilization forms over 2 years. Key outcome variables were the incidence of symptomatic disease, medical costs, and patient-reported health.

RESULTS

Sixteen screened subjects (64%) had abnormal findings on screening. A second interpretation of the images yielded a similar overall rate but with considerable variability at the subject level. No cancers were detected. Ninety percent of subjects were compliant at 2 years. Medical costs were twice as high for screened subjects, with considerable between-subject variability. Screened subjects reported fewer physical limitations than unscreened subjects.

CONCLUSION

A full-scale randomized controlled trial of total-body screening will need to account for the large interreader variability in interpreting the images, the high rate of incidental findings, and the low prevalence of cancers. A full-scale study using mortality as the endpoint does not seem feasible at this time.

Computed tomography and radiation: understanding the issues

We are currently seeing increasing opportunities to improve patient care with computed tomography (CT). At the same time, we are challenged to use this technology wisely. In particular, we are being asked to balance the benefits against the risks, chiefly those of ionizing radiation. To do this, we must have a foundation from which to determine the relative risks. This foundation necessarily must be composed of several components. First, it is important to understand the patterns of use and increasing application of CT, particularly multidetector CT. In addition, it is helpful to be familiar with measures of radiation pertinent to CT and the doses provided by this modality. This foundation then provides a context in which to discuss the issue of low-dose radiation and cancer risk as well as potential changes in CT practice guidelines and regulation. It is with an understanding of these issues that radiologists and other radiology personnel can participate in an informed discussion with referring physicians and patients and continue to optimize the practice of CT.

Body diffusion-weighted MR imaging using high b-value for malignant tumor screening: usefulness and necessity of referring to T2-weighted images and creating fusion images

RATIONALE AND OBJECTIVES

To evaluate the potential usefulness of high b-value body diffusion-weighted images (DWIs) as a screening tool in the depiction of abdominal malignant tumors.

MATERIALS AND METHODS

We selected 110 abdominal magnetic resonance examinations (1.5 T; 60 men; age range, 25-90 years) with and without malignant tumors (n = 37 and n = 73, respectively). Axial DWIs were obtained by single-shot spin-echo (SE) type echo planar imaging (EPI) sequence with inversion pulse (repetition time, 6,800 msec; echo time, 100 msec; T1, 150 msec; b value, 1,000 sec/mm(2)) without breath-holding. Two radiologists independently interpreted the DWIs, T2-weighted images (T2-WI), all three types of images including DWIs, T2-WIs, and fusion images at the same time (DWIs + T2-WIs + fusion) with 7-14 days' interval, and the diagnostic confidence for each patient was scored.

RESULTS

The area under the curve (AUC) of the composite receiver operating characteristic (ROC) curve of DWIs + T2-WIs + fusion (0.904) was significantly higher than those of DWIs (0.720; P < .001) and T2-WIs (0.822; P < .05). Both sensitivity and specificity were higher in DWIs + T2-WIs + fusion (89.5% and 81.9%, respectively) compared with those of DWIs (72.4% and 59.0%; P < .01 and P < .001, respectively).

CONCLUSIONS

Abdominal high b-value DWIs have a high sensitivity and specificity for malignant tumors when T2-WIs are referred and image fusion technique is employed, suggesting that it may potentially be a new screening tool.

Patient Expectations of Full-Body CT Screening

OBJECTIVE

Despite limited scientific evidence about its risks and benefits, full-body CT screening is available to self-referred individuals. The purpose of this study was to develop a scientific knowledge base about patient expectations of the procedure and to determine whether characteristics of patients influence their expectations of its health benefits.

MATERIALS AND METHODS

Facilities from six diverse, geographically representative U.S. regions performing full-body CT screening were used as the study sites. A pretest only descriptive survey design was used to study 94 patient volunteers scheduled to undergo full-body CT screening. Descriptive statistics were used in examining information about the demographics, health, and knowledge characteristics of the patients. The chi-square test for independence and Spearman's correlation coefficient for ranked data were used to analyze associations among patient characteristics and responses to expectation statements. An alpha value of 0.05 was the level of significance.

RESULTS

Survey participants were 35-65 years old, predominantly white, married, and health conscious with income and educational levels several times above the national averages. The patients' highest expectations related to consumer empowerment and their lowest expectations related to the limitations of the procedure. The five patient characteristics found to have significant associations with patient expectations were patient sex; referral method; level of personal health concern; number of other health screening procedures patient had undergone; and patients' self-estimations of their current health status.

CONCLUSION

This study provided quantitative and descriptive data that are consistent with and add to the existing, primarily anecdotal, knowledge base about patients' expectations of full-body CT screening. These findings can be used to educate patients before they provide informed consent for the procedure.

Periampullary and pancreatic incidentaloma: a single institution's experience with an increasingly common diagnosis

BACKGROUND

While incidental masses in certain organs have received particular attention, periampullary and pancreatic incidentalomas (PIs) remain poorly characterized.

METHODS

We reviewed 1944 consecutive pancreaticoduodenectomies (PD) over an 8-year period (April 1997 to October 2005). A total of 118 patients (6% of all PDs) presented with an incidental finding of a periampullary or pancreatic mass. The PI patients were analyzed and compared with the rest of the cohort (NI, nonincidentaloma group, n = 1826).

RESULTS

Thirty-one percent of the PI patients (n = 37) had malignant disease (versus 76% of the NI patients, P < 0.001), 47% (n = 55) had premalignant disease, and the remaining 22% (n = 26) had little or no risk for malignant progression. The 3 most common diagnoses in the PI group were IPMN without invasive cancer (30%), cystadenoma (17%), and pancreatic ductal adenocarcinoma (10%). The PI group had a higher overall complication rate (55% versus 43%, P = 0.02), due in part to a significantly increased rate of pancreatic fistulas (18.4% PI versus 8.5% NI, P < 0.001). Patients in the PI group with malignant disease had a superior long-term survival (median, 30 months, P = 0.01) compared with patients in the NI group with malignant disease (median, 21 months).

CONCLUSIONS

Incidentally discovered periampullary and pancreatic masses comprise a substantial proportion of patients undergoing PD. Roughly three fourths of these lesions are malignant or premalignant, and amenable to curative resection. Resected malignant PIs have favorable pathologic features as compared with resected malignant NIs, and resection of these early lesions in asymptomatic individuals is associated with improved survival, compared with patients with symptomatic disease.

Total body screening: predicting actionable findings

RATIONALE AND OBJECTIVES

Total body screening, despite its popularity, has not been evaluated in clinical trials. Even the appropriate target for screening has not been addressed. In this study, we determined the variables from a subject's demographic and medical and family history that are predictive of actionable findings on total body screening.

MATERIALS AND METHODS

Over a 3-year period, 982 self-referred subjects underwent total body screening with multislice computed tomography and completed a demographic and medical history questionnaire. The study sample was divided into training and testing samples. Univariate and multiple-variable statistical methods were used on the training sample to derive models that predict actionable lung findings, actionable heart findings, actionable abdomen/pelvis findings, and any actionable findings on total body screening. The training models were then applied and evaluated on the test sample.

RESULTS

A subject's age at the time of screening was the single most important predictor and often the only significant predictor of actionable findings. Among subjects younger than 40 years of age, 22.5% had actionable findings; this number nearly doubled, to 43.5%, for subjects between 40 and 49, and increased to 80% for subjects 80 years and older. Overall, every increase of 10 years in age brings an increase of 1.6 in the likelihood of an actionable finding.

CONCLUSIONS

Total body screening targeted at older subjects has the highest yield of actionable findings. The efficacy and cost-effectiveness of total body screening for older subjects is unknown and needs further assessment.

Whole-body CT screening: spectrum of findings and recommendations in 1192 patients

PURPOSE

To retrospectively determine the frequency and spectrum of findings and recommendations reported with whole-body computed tomographic (CT) screening at a community screening center.

MATERIALS AND METHODS

This HIPAA-compliant study received institutional review board approval, with waiver of informed consent. The radiologic reports of 1192 consecutive patients who underwent whole-body CT screening of the chest, abdomen, and pelvis at an outpatient imaging center from January to June 2000 were reviewed. Scans were obtained with electron-beam CT without oral or intravenous contrast material. Reported imaging findings and recommendations were retrospectively tabulated and assigned scores. Descriptive statistics were used (means, standard deviations, and percentages); comparisons between subgroups were performed with univariate analysis of variance and chi(2) or Fisher exact tests.

RESULTS

Screening was performed in 1192 patients (mean age, 54 years). Sixty-five percent (774 of 1192) were men and 35% (418 of 1192) were women. Nine hundred three (76%) of 1192 patients were self referred, and 1030 (86%) of 1192 subjects had at least one abnormal finding described in the whole-body CT screening report. There were a total of 3361 findings, with a mean of 2.8 per patient. Findings were described most frequently in the spine (1065 [32%] of 3361), abdominal blood vessels (561 [17%] of 3361), lungs (461 [14%] of 3361), kidneys (353 [11%] of 3361), and liver (183 [5%] of 3361). Four hundred forty-five (37%) patients received at least one recommendation for further evaluation. The most common recommendations were for additional imaging of the lungs or the kidneys.

CONCLUSION

With whole-body CT screening, findings were detected in a large number of subjects, and most findings were benign by description and required no further evaluation. Thirty-seven percent of patients had findings that elicited recommendations for additional evaluation, but further research is required to determine the clinical importance of these findings and the effect on patient care.

Cost-effectiveness of whole-body CT screening

PURPOSE

To make preliminary estimates of the effectiveness (in life-years) and cost-effectiveness (in costs per life-year) of whole-body computed tomographic (CT) screening.

MATERIALS AND METHODS

Costs and effectiveness (in life-years) of onetime whole-body CT screening relative to those of no screening were calculated by using a decision-analytic model. It was assumed that any benefits from screening were due to earlier detection of disease and improvement in survival relative to survival with routine care. Eight conditions were included in the model: ovarian, pancreatic, lung, liver, kidney, and colon cancer; abdominal aortic aneurysm; and coronary artery disease. Costs of the screening examination, follow-up tests, and patient care were estimated. The base-case analysis was performed for a hypothetical cohort of 500 000 self-referred asymptomatic 50-year-old men. For sensitivity analyses, the age and sex of the cohort were varied. Results were expressed in 2001 U.S. dollars per life-year gained.

RESULTS

Compared with routine care, whole-body CT screening provided minimal gains in life expectancy (0.016 6 years or 6 days) at an average additional cost of 2513 dollars per patient, or an incremental cost-effectiveness ratio of 151 000 dollars per life-year gained. Most patients (90.8%) had at least one positive finding, but only 2.0% had disease; work-up in patients with a false-positive result of screening accounted for 32.3% of total costs (1720 dollars of 5332 dollars). Results were sensitive to the prevalence of disease, the effect of screening on stage of disease at diagnosis, the specificity of screening, and the costs of follow-up for false-positive findings.

CONCLUSION

Even with assumptions favorable to whole-body CT, implementation of onetime screening would not be cost-effective compared with currently funded medical interventions; follow-up for false-positive findings would add a substantial financial burden to the health care system.

The future of imaging screening: Proceedings of the Fourth Annual ACR FORUM

The FORUM is an ACR planning activity focused on a specific topic deemed to be of long-range importance to the college. A select panel of multidisciplinary experts met in 2004 to consider the ramifications of imaging screening from diverse perspectives. Considerations included the nature of screening for disease, its technological issues, and biases associated with the perceived success of screening; potential technologies and target diseases; business and economics; insurance coverage; ethics and the law; how imaging screening could be paired with nonimaging screening; and how the lay public perceives screening. The FORUM participants considered how imaging screening might develop over the next 5 to 10 years and made recommendations to the ACR on actions it might take to benefit both the specialty and patients.

The appropriateness of employing imaging screening technologies: Report of the methods committee of the ACR task force on screening technologies

Screening for disease using imaging technologies is a growing phenomenon. For some applications (e.g., mammography and breast cancer), there is solid evidence that imaging screening reduces disease-specific mortality. However, for other applications, the public interest in imaging screening is progressing despite a lack of valid scientific evidence that such screening improves the public's health. Clinical trials promise to eventually shed light on the value of imaging screening, but the results of these trials will not be known for several years. In the meantime, physicians and the public need guidance on whether specific imaging screening examinations are appropriate. The ACR charged the Methods Committee of its Task Force on Screening Technologies to advise the organization on how it could best use available evidence to make public recommendations on imaging screening technologies. This article is the outcome of the committee's deliberations, including recommendations for the method of arriving at a recommendation, the approach to dissemination, and to whom the recommendations should be targeted.

Self-referred Whole-Body Imaging: Where Are We Now?

PURPOSE

To identify current patterns and trends of computed tomographic (CT) screening, including geographic data, services provided, facility type, and demographic characteristics.

MATERIALS AND METHODS

In March 2003, self-referred body imaging (SRBI) centers were identified by using the Internet. Data involving geographic location, type of facility, services provided, and demographic characteristics were collected. The 2000 U.S. census data were used to compare center locality demographics with national patterns. Descriptive statistics, t tests, and regression analyses were used to evaluate data. Nonstatistical comparisons were made with results obtained from a previously published analysis.

RESULTS

The number of SRBI centers totaled 161 (vs 88 in a comparative study in 2001), and centers were distributed across 31 states and Washington, DC (vs 21 in 2001). Racial demographics of center localities more closely resembled national averages in the current study, with equal percentages of whites (76.0% vs 77.1% nationally) and Hispanics (11.5% vs 12.5% nationally). Center localities continued to exhibit greater wealth and levels of education, as reflected by higher income per capita and median household income (P < .05), as well as by higher percentages of people with college and advanced degrees (P < .05). Heart scanning was the most commonly offered service (n = 152, 94%), followed by whole-body scanning (n = 135, 84%), lung scanning (n = 126, 78%), and virtual colonoscopy (n = 88, 55%). Centers in the West were more likely to offer whole-body and organ-specific scanning, compared with centers in other regions (P < .001 for virtual colonoscopy, P < .05 for head scanning). Hospital-based centers were less likely to offer services other than heart scanning (P < .001).

CONCLUSION

Compared with results of a prior analysis, SRBI centers have increased and are distributed more widely in areas with a population that more closely resembles national norms. The increased trend to broaden services may suggest possible saturation of the preexisting market.

Estimated radiation risks potentially associated with full-body CT screening

PURPOSE

To estimate the radiation-related cancer mortality risks associated with single or repeated full-body computed tomographic (CT) examinations by using standard radiation risk estimation methods.

MATERIALS AND METHODS

The estimated dose to the lung or stomach from a single full-body CT examination is 14-21 mGy, which corresponds to a dose region for which there is direct evidence of increased cancer mortality in atomic bomb survivors. Total doses for repeated examinations are correspondingly higher. The authors used estimated cancer risks in a U.S. population derived from atomic bomb-associated cancer mortality data, together with calculated organ doses from a full-body CT examination, to estimate the radiation risks associated with single and multiple full-body CT examinations.

RESULTS

A single full-body CT examination in a 45-year-old adult would result in an estimated lifetime attributable cancer mortality risk of around 0.08%, with the 95% credibility limits being a factor of 3.2 in either direction. A 45-year-old adult who plans to undergo annual full-body CT examinations up to age 75 (30 examinations) would accrue an overall estimated lifetime attributable risk of cancer mortality of about 1.9%, with the 95% credibility limits being a factor of 2 in either direction.

CONCLUSION

The authors provide estimates of lifetime cancer mortality risks from both single and annual full-body CT examinations. These risk estimates are needed to assess the utility of full-body CT examinations from both an individual and a public health perspective.

Trends in on-call workload in an academic medical center radiology department 1998-20021

RATIONALE AND OBJECTIVES

The workload in radiology departments is increasing rapidly. This study was designed to determine whether and to what extent the workload is being generated outside of traditional working hours (defined as 0800-1700 Monday thru Friday, excluding holidays).

MATERIALS AND METHODS

Exam statistics were derived from the radiology department's automated examination scheduling and reporting system for four successive fiscal years. The distribution of the number of studies completed throughout the 24-hour day and the 7-day week was charted.

RESULTS

A large proportion of studies are being completed outside of traditional working hours. Moreover, as the overall workload of the department increased, the proportion of studies being completed during nontraditional working hours was increasing at an even faster pace, particularly in the cross-sectional imaging modalities. Computed tomography, magnetic resonance imaging, and ultrasound have increased by 59%, 51%, and 30%, respectively, over 4 years. The on-call proportions have increased from 34% to 40% and 13% to 18% for computed tomography and ultrasound, respectively, over 4 years and from 44% to 50% for magnetic resonance imaging over 3 years.

CONCLUSION

These trends have implications for radiologist and radiology technologist staffing. The department has already modified the scheduling of technologist staffing to provide in-house extended-hours coverage in most modalities. As the number of studies conducted outside of traditional working hours continues to expand and the demand for contemporaneous readings increases, radiologist staffing may need to be adjusted as well. Traditional on-call coverage may be insufficient to competently handle the growing workload. This may have particular implications for radiology residency programs.

Screening computed tomography: will it result in overdiagnosis of renal carcinoma?

BACKGROUND

Despite uncertain benefits and harms, screening computed tomography (CT) is being marketed to consumers in the U.S. One plausible harm is the detection and treatment of renal carcinoma cases that otherwise would have remained clinically silent during the patient's lifetime.

METHODS

After estimating the prevalence of preclinical renal carcinoma using meta-analysis of five series of asymptomatic, middle-aged Americans who received CT screening, the authors divided the prevalence by U.S. incidence rates of clinical renal carcinoma among persons of similar age. This calculation would estimate the mean duration of the detectable preclinical period (the "sojourn time") of renal carcinoma if the incidence of preclinical and clinical renal carcinoma were equivalent.

RESULTS

The 5 series included 16,174 screenees (mean age range, 58-64 years; 61% male). The prevalence of asymptomatic renal carcinoma ranged from 0.11% to 0.76%; the pooled prevalence was 0.21% (95% confidence interval, 0.14-0.28%). The estimated mean sojourn time for renal carcinoma was between 3.7 years and 5.8 years among middle-aged Americans.

CONCLUSIONS

Because most renal carcinomas grow slowly during the preclinical period, the authors' estimated mean sojourn time did not seem unduly long. Therefore, the incidence rate of clinical renal carcinoma most likely is a reasonable surrogate for the incidence rate of preclinical renal carcinoma, implying that most renal carcinomas detected by CT screening among middle-aged Americans are likely to progress to clinical diagnosis.

Computed tomography and radiation risks: what pediatric health care providers should know

Computed tomography (CT) is an extremely valuable diagnostic tool. Recent advances, particularly multidetector technology, have provided increased and more diverse applications. However, there is also the potential for inappropriate use and unnecessary radiation dose. Because some data indicate that low-dose radiation (such as that in CT) may have a significant risk of cancer, especially in young children, it is important to limit CT radiation by following the ALARA (as low as reasonably achievable) principle. There is a variety of strategies to limit radiation dose, including performing only necessary examinations, limiting the region of coverage, and adjusting individual CT settings based on indication, region imaged, and size of the child. The pediatric health care provider has a pivotal role in the performance of CT and may be the only individual who discusses these important CT radiation issues with the child and family. For this reason, this article will summarize the issues with CT patterns of use and radiation risk, and provide dose reduction strategies pertinent to pediatric health care providers.