Role of CT in the Diagnosis of Nonspecific Abdominal Pain: A Multicenter Analysis.

OBJECTIVE: The objective of our study was to determine whether specific patient and physician factors-known before CT-are associated with a diagnosis of nonspecific abdominal pain (NSAP) after CT in the emergency department (ED). MATERIALS AND METHODS: We analyzed data originally collected in a prospective multicenter study. In the parent study, we identified ED patients referred to CT for evaluation of abdominal pain. We surveyed their physicians before and after CT to identify changes in leading diagnoses, diagnostic confidence, and admission decisions. In the current study, we conducted a multiple regression analysis to identify whether the following were associated with a post-CT diagnosis of NSAP: patient age; patient sex; physicians' years of experience; physicians' pre-CT diagnostic confidence; and physicians' pre-CT admission decision if CT had not been available. We analyzed patients with and those without a pre-CT diagnosis of NSAP separately. For the sensitivity analysis, we excluded patients with different physicians before and after CT. RESULTS: In total, 544 patients were included: 10% (52/544) with a pre-CT diagnosis of NSAP and 90% (492/544) with a pre-CT diagnosis other than NSAP. The leading diagnoses changed after CT in a large proportion of patients with a pre-CT diagnosis of NSAP (38%, 20/52). In regression analysis, we found that physicians' pre-CT diagnostic confidence was inversely associated with a post-CT diagnosis of NSAP in patients with a pre-CT diagnosis other than NSAP (p = 0.0001). No other associations were significant in both primary and sensitivity analyses. CONCLUSION: With the exception of physicians' pre-CT diagnostic confidence, the factors evaluated were not associated with a post-CT diagnosis of NSAP.

Changes in Physician Decision Making after CT: A Prospective Multicenter Study in Primary Care Settings.

Purpose To determine the effect of computed tomography (CT) results on physician decision making in three common clinical scenarios in primary care. Materials and Methods This research was approved by the institutional review board (IRB) and was HIPAA compliant. All physicians consented to participate with an opt-in or opt-out mechanism; patient consent was waived with IRB approval. In this prospective multicenter observational study, outpatients referred by primary care providers (PCPs) for CT evaluation of abdominal pain, hematuria, or weight loss were identified. Prior to CT, PCPs were surveyed to elicit their leading diagnosis, confidence in that diagnosis (confidence range, 0%-100%), a rule-out diagnosis, and a management plan if CT were not available. Surveys were repeated after CT. Study measures were the proportion of patients in whom leading diagnoses and management changed (PCP management vs specialist referral vs emergency department transfer), median changes in diagnostic confidence, and the proportion of patients in whom CT addressed rule-out diagnoses. Regression analyses were used to identify associations between study measures and site and participant characteristics. Specifically, logistic regression analysis was used for binary study measures (change in leading diagnosis, change in management), and linear regression analysis was used for the continuous study measure (change in diagnostic confidence). Accrual began on September 5, 2012, and ended on June 28, 2014. Results In total, 91 PCPs completed pre- and post-CT surveys in 373 patients. In patients with abdominal pain, hematuria, or weight loss, leading diagnoses changed after CT in 53% (131 of 246), 49% (36 of 73), and 57% (27 of 47) of patients, respectively. Management changed in 35% (86 of 248), 27% (20 of 74), and 54% (26 of 48) of patients, respectively. Median absolute changes in diagnostic confidence were substantial and significant (+20%, +20%, and +19%, respectively; P ≤ .001 for all); median confidence after CT was high (90%, 88%, and 80%, respectively). PCPs reported CT was helpful in confirming or excluding rule-out diagnoses in 98% (184 of 187), 97% (59 of 61), and 97% (33 of 34) of patients, respectively. Significant associations between primary measures and site and participant characteristics were not identified. Conclusion Changes in PCP leading diagnoses and management after CT were common, and diagnostic confidence increased substantially. © RSNA, 2016 Online supplemental material is available for this article.

CT in the Emergency Department: A Real-Time Study of Changes in Physician Decision Making.

PURPOSE: To determine how physicians' diagnoses, diagnostic uncertainty, and management decisions are affected by the results of computed tomography (CT) in emergency department settings. MATERIALS AND METHODS: This study was approved by the institutional review board and compliant with HIPAA. Data were collected between July 12, 2012, and January 13, 2014. The requirement to obtain patient consent was waived. In this prospective, four-center study, patients presenting to the emergency department who were referred for CT with abdominal pain, chest pain and/or dyspnea, or headache were identified. Physicians were surveyed before and after CT to determine the leading diagnosis, diagnostic confidence (on a scale of 0% to 100%), alternative "rule out" diagnosis, and management decisions. Primary measures were the proportion of patients for whom the leading diagnosis or admission decision changed and median changes in diagnostic confidence. Secondary measures addressed alternative diagnoses and return-to-care visits (eg, to emergency department) at 1-month follow-up. Regression analysis was used to identify associations between primary measures and site and participant characteristics. RESULTS: Both surveys were completed for 1280 patients by 245 physicians. The leading diagnosis changed in 235 of 460 patients with abdominal pain (51%), 163 of 387 with chest pain and/or dyspnea (42%), and 103 of 433 with headache (24%). Pre-CT diagnostic confidence was inversely associated with the likelihood of a diagnostic change (P < .0001). Median changes in confidence were substantial (increases of 25%, 20%, and 13%, respectively, for patients with abdominal pain, chest pain and/or dyspnea, and headache; P < .0001); median post-CT confidence was high (95% for all three groups). CT helped confirm or exclude at least 95% of alternative diagnoses. Admission decisions changed in 116 of 457 patients with abdominal pain (25%), 72 of 387 with chest pain and/or dyspnea (19%), and 81 of 426 with headache (19%). During follow-up, 70 of 450 patients with abdominal pain (15%), 53 of 387 with chest pain and/or dyspnea (14%), and 49 of 433 with headache (11%) returned for the same indication. In general, changes in leading diagnosis, diagnostic confidence, and admission decisions were not well explained with site or participant characteristics. CONCLUSION: Physicians' diagnoses and admission decisions changed frequently after CT, and diagnostic uncertainty was alleviated.

Communicating Potential Radiation-Induced Cancer Risks From Medical Imaging Directly to Patients.

OBJECTIVE: Over the past decade, efforts have increasingly been made to decrease radiation dose from medical imaging. However, there remain varied opinions about whether, for whom, by whom, and how these potential risks should be discussed with patients. We aimed to provide a review of the literature regarding awareness and communication of potential radiation-induced cancer risks from medical imaging procedures in hopes of providing guidance for communicating these potential risks with patients. MATERIALS AND METHODS: We performed a systematic literature review on the topics of radiation dose and radiation-induced cancer risk awareness, informed consent regarding radiation dose, and communication of radiation-induced cancer risks with patients undergoing medical imaging. We included original research articles from North America and Europe published between 1995 and 2014. RESULTS: From more than 1200 identified references, a total of 22 original research articles met our inclusion criteria. Overall, we found that there is insufficient knowledge regarding radiation-induced cancer risks and the magnitude of radiation dose associated with CT examinations among patients and physicians. Moreover, there is minimal sharing of information before nonacute imaging studies between patients and physicians about potential long-term radiation risks. CONCLUSION: Despite growing concerns regarding medical radiation exposure, there is still limited awareness of radiation-induced cancer risks among patients and physicians. There is also no consensus regarding who should provide patients with relevant information, as well as in what specific situations and exactly what information should be communicated. Radiologists should prioritize development of consensus statements and novel educational initiatives with regard to radiation-induced cancer risk awareness and communication.

Radiation exposure from CT-guided ablation of renal masses: effects on life expectancy.

OBJECTIVE. The purpose of this article is to project the effects of radiation exposure on life expectancy (LE) in patients who opt for CT-guided radiofrequency ablation (RFA) instead of surgery for renal cell carcinoma (RCC). MATERIALS AND METHODS. We developed a decision-analytic Markov model to compare LE losses attributable to radiation exposure in hypothetical 65-year-old patients who undergo CT-guided RFA versus surgery for small (≤ 4 cm) RCC. We incorporated mortality risks from RCC, radiation-induced cancers (for procedural and follow-up CT scans), and all other causes; institutional data informed the RFA procedural effective dose. Radiation-induced cancer risks were generated using an organ-specific approach. Effects of varying model parameters and of dose-reduction strategies were evaluated in sensitivity analysis. RESULTS. Cumulative RFA exposures (up to 305.2 mSv for one session plus surveillance) exceeded those from surgery (up to 87.2 mSv). In 65-year-old men, excess LE loss from radiation-induced cancers, comparing RFA to surgery, was 11.7 days (14.6 days for RFA vs 2.9 days for surgery). Results varied with sex and age; this difference increased to 14.6 days in 65-year-old women and to 21.5 days in 55-year-old men. Dose-reduction strategies that addressed follow-up rather than procedural exposure had a greater impact. In 65-year-old men, this difference decreased to 3.8 days if post-RFA follow-up scans were restricted to a single phase; even elimination of RFA procedural exposure could not achieve equivalent benefits. CONCLUSION. CT-guided RFA remains a safe alternative to surgery, but with decreasing age, the higher burden of radiation exposure merits explicit consideration. Dose-reduction strategies that target follow-up rather than procedural exposure will have a greater impact.

Microsimulation model of CT versus MRI surveillance of Bosniak IIF renal cystic lesions: should effects of radiation exposure affect selection of imaging strategy?

OBJECTIVE: The objective of this study was to quantify the effects of radiation-induced cancer risks in patients with Bosniak category IIF lesions undergoing CT versus MRI surveillance. MATERIALS AND METHODS: We developed a Markov-Monte Carlo model to determine life expectancy losses attributable to radiation-induced cancers in hypothetical patients undergoing CT versus MRI surveillance of Bosniak IIF lesions. Our model tracked hypothetical patients as they underwent imaging surveillance for up to 5 years, accounting for potential lesion progression and treatment. Estimates of radiation-induced cancer mortality were generated using a published organ-specific radiation-risk model based on Biological Effects of Ionizing Radiation VII methods. The model also incorporated surgical mortality and renal cancer-specific mortality. Our primary outcome was life expectancy loss attributable to radiation-induced cancers. A sensitivity analysis was performed to assess the stability of the results with variability in key parameters. RESULTS: The mean number of examinations per patient was 6.3. In the base case, assuming 13 mSv per multiphase CT examination, 64-year-old men experienced an average life expectancy decrease of 5.5 days attributable to radiation-induced cancers from CT; 64-year-old women experienced a corresponding life expectancy loss of 6.9 days. The results were most sensitive to patient age: Life expectancy loss attributable to radiation-induced cancers increased to 21.6 days in 20-year-old women and 20.0 days in 20-year-old men. Varied assumptions of each modality's (CT vs MRI) depiction of lesion complexity also impacted life expectancy losses. CONCLUSION: Microsimulation modeling shows that radiation-induced cancer risks from CT surveillance for Bosniak IIF lesions minimally affect life expectancy. However, as progressively younger patients are considered, increasing radiation risks merit stronger consideration of MRI surveillance.

Imaging for appendicitis: should radiation-induced cancer risks affect modality selection?

PURPOSE: To compare life expectancy (LE) losses attributable to three imaging strategies for appendicitis in adults-computed tomography (CT), ultrasonography (US) followed by CT for negative or indeterminate US results, and magnetic resonance (MR) imaging-by using a decision-analytic model. MATERIALS AND METHODS: In this model, for each imaging strategy, LE losses for 20-, 40-, and 65-year-old men and women were computed as a function of five key variables: baseline cohort LE, test performance, surgical mortality, risk of death from delayed diagnosis (missed appendicitis), and LE loss attributable to radiation-induced cancer death. Appendicitis prevalence, test performance, mortality rates from surgery and missed appendicitis, and radiation doses from CT were elicited from the published literature and institutional data. LE loss attributable to radiation exposure was projected by using a separate organ-specific model that accounted for anatomic coverage during a typical abdominopelvic CT examination. One- and two-way sensitivity analyses were performed to evaluate effects of model input variability on results. RESULTS: Outcomes across imaging strategies differed minimally-for example, for 20-year-old men, corresponding LE losses were 5.8 days (MR imaging), 6.8 days (combined US and CT), and 8.2 days (CT). This order was sensitive to differences in test performance but was insensitive to variation in radiation-induced cancer deaths. For example, in the same cohort, MR imaging sensitivity had to be 91% at minimum (if specificity were 100%), and MR imaging specificity had to be 62% at minimum (if sensitivity were 100%) to incur the least LE loss. Conversely, LE loss attributable to radiation exposure would need to decrease by 74-fold for combined US and CT, instead of MR imaging, to incur the least LE loss. CONCLUSION: The specific imaging strategy used to diagnose appendicitis minimally affects outcomes. Paradigm shifts to MR imaging owing to concerns over radiation should be considered only if MR imaging test performance is very high.

Prioritizing examination-centered over patient-centered dose reduction: a hazard of institutional "benchmarking".

OBJECTIVE: The purpose of this article is to evaluate whether examination-specific radiation dose metrics reliably measure an institution's success in reducing cancer risks. MATERIALS AND METHODS: We projected health benefits from dose-reduction programs in a hypothetical institution that sought to decrease exposures from abdominopelvic CT. Using modeling techniques to project radiation-induced cancer risks and tertiary center data to inform the institution's abdominopelvic CT age distribution, we compared a program in which effective doses were reduced equally (from 10 to 7 mSv) across all scans with programs in which dose reduction was age dependent. For each program, we projected lethal cancers averted, life expectancy gained, and average institutional dose achieved. Markov Chain Monte Carlo methods were used to estimate uncertainty in projections. RESULTS: The analysis's age distribution drew from 20,979 CT scans; 39% were from patients 65 years old and older. To illustrate trends yielded, if all patients in the hypothetical institution underwent 7-mSv (instead of 10-mSv) scans, we projected the maximum number of lethal cancers averted to be seven per 100,000 patients, and maximum life expectancy gained to be 0.26 days per patient, when averaged over the institution's population. When restricting dose reduction (from 10 to 7 mSv) to patients younger than 65 years, benefits were slightly lower (five lethal cancers averted per 100,000 patients and 0.22 days per patient gained); however, the average institutional dose was substantially higher (8.2 mSv). Although dose reduction in patients 65 years old and older accounted for only 16% of possible institutional life expectancy gains, this patient group contributed disproportionately (39%) to the institution's average dose. CONCLUSION: Institutional examination-specific dose metrics can be misleading, because the least-benefited patients may contribute disproportionately toward "improved" averages.

The fisherman's cards: how to address past and future radiation exposures in clinical decision making.

OBJECTIVE. The purpose of this article is to describe how to address patients' past-and future potential-radiation exposures when making an imaging decision in a given situation. CONCLUSION. The Biologic Effects of Ionizing Radiation committee has endorsed a linear no-threshold model to explain the relationship between radiation exposure and cancer risk. This model implies that past and future potential exposures should not impact current decisions. We present an analogy that deconstructs these counterintuitive conclusions and facilitates translation of key radiation risk principles to practice.

Journal club: How radiation exposure histories influence physician imaging decisions: a multicenter radiologist survey study.

OBJECTIVE: The purpose of this article is to evaluate the influence of patient radiation exposure histories on radiologists' imaging decisions. MATERIALS AND METHODS: We conducted a physician survey study in three academic medical centers. Radiologists were asked to make an imaging recommendation for a hypothetical patient with a history of multiple CT scans. We queried radiologists' decision making, evaluating whether they incorporated cancer risks from previous imaging, reported acceptance (or rejection) of the linear no-threshold model, and understood linear no-threshold model implications in this setting. Consistency between radiologists' decisions and their linear no-threshold model beliefs was evaluated; those acting in accordance with the linear no-threshold model were expected to disregard previously incurred cancer risks. A Fisher exact test was used to verify the generalizability of results across institutions and training levels (residents, fellows, and attending physicians). RESULTS: Fifty-six percent (322/578) of radiologists completed the survey. Most (92% [295/322]) incorporated risks from the patient's exposure history during decision making. Most (61% [196/322]) also reported acceptance of the linear no-threshold model. Fewer (25% [79/322]) rejected the linear no-threshold model; 15% (47/322) could not judge. Among radiologists reporting linear no-threshold model acceptance or rejection, the minority (36% [98/275]) made decisions that were consistent with their linear no-threshold model beliefs. This finding was not statistically different across institutions (p = 0.070) or training levels (p = 0.183). Few radiologists (4% [13/322]) had an accurate understanding of linear no-threshold model implications. CONCLUSION: Most radiologists, when faced with patient exposure histories, make decisions that contradict their self-reported acceptance of the linear no-threshold model and the linear no-threshold model itself. These findings underscore a need for educational initiatives.

Optimizing adjuvant treatment decisions for stage t2 rectal cancer based on mesorectal node size: a decision analysis.

RATIONALE AND OBJECTIVES: The aim of this study was to optimize treatment decisions for patients with suspected stage T2 rectal cancer on the basis of mesorectal lymph node size at magnetic resonance imaging. MATERIALS AND METHODS: A decision-analytic model was developed to predict outcomes for patients with stage T2 rectal cancer at magnetic resonance imaging. Node-positive patients were assumed to benefit from chemoradiation prior to surgery. Imperfect magnetic resonance imaging performance for primary cancer and mesorectal nodal staging was incorporated. Five triage strategies were considered for administering preoperative chemoradiation: treat all patients; treat for any mesorectal node >3, >5, and >7 mm in size; and treat no patients. If nodal metastases or unsuspected stage T3 disease went untreated preoperatively, postoperative chemoradiation was needed, resulting in poorer outcomes. For each strategy, rates of acute and long-term chemoradiation toxicity and of 5-year local recurrence were computed. Effects of input parameter uncertainty were evaluated in sensitivity analysis. RESULTS: The optimal strategy depended on the outcome prioritized. Acute and long-term chemoradiation toxicity rates were minimized by triaging only patients with nodes >7 mm to preoperative chemoradiation (18.9% and 10.8%, respectively). A treat-all strategy minimized the 5-year local recurrence rate (5.6%). A 7-mm nodal triage threshold increased the 5-year local recurrence rate to 8.0%; when no patients were treated preoperatively, the local recurrence rate was 10.1%. With improved primary tumor staging, all outcomes could be further optimized. CONCLUSIONS: Mesorectal nodal size thresholds for preoperative chemoradiation should depend on the outcome prioritized: higher size thresholds reduce chemoradiation toxicity but increase recurrence rates. Improvements in nodal staging will have greater impact if primary tumor staging can be improved.

Patients with testicular cancer undergoing CT surveillance demonstrate a pitfall of radiation-induced cancer risk estimates: the timing paradox.

PURPOSE: To demonstrate a limitation of lifetime radiation-induced cancer risk metrics in the setting of testicular cancer surveillance-in particular, their failure to capture the delayed timing of radiation-induced cancers over the course of a patient's lifetime. MATERIALS AND METHODS: Institutional review board approval was obtained for the use of computed tomographic (CT) dosimetry data in this study. Informed consent was waived. This study was HIPAA compliant. A Markov model was developed to project outcomes in patients with testicular cancer who were undergoing CT surveillance in the decade after orchiectomy. To quantify effects of early versus delayed risks, life expectancy losses and lifetime mortality risks due to testicular cancer were compared with life expectancy losses and lifetime mortality risks due to radiation-induced cancers from CT. Projections of life expectancy loss, unlike lifetime risk estimates, account for the timing of risks over the course of a lifetime, which enabled evaluation of the described limitation of lifetime risk estimates. Markov chain Monte Carlo methods were used to estimate the uncertainty of the results. RESULTS: As an example of evidence yielded, 33-year-old men with stage I seminoma who were undergoing CT surveillance were projected to incur a slightly higher lifetime mortality risk from testicular cancer (598 per 100 000; 95% uncertainty interval [UI]: 302, 894) than from radiation-induced cancers (505 per 100 000; 95% UI: 280, 730). However, life expectancy loss attributable to testicular cancer (83 days; 95% UI: 42, 124) was more than three times greater than life expectancy loss attributable to radiation-induced cancers (24 days; 95% UI: 13, 35). Trends were consistent across modeled scenarios. CONCLUSION: Lifetime radiation risk estimates, when used for decision making, may overemphasize radiation-induced cancer risks relative to short-term health risks.

Using radiation risk models in cancer screening simulations: important assumptions and effects on outcome projections.

PURPOSE: To evaluate the effect of incorporating radiation risk into microsimulation (first-order Monte Carlo) models for breast and lung cancer screening to illustrate effects of including radiation risk on patient outcome projections. MATERIALS AND METHODS: All data used in this study were derived from publicly available or deidentified human subject data. Institutional review board approval was not required. The challenges of incorporating radiation risk into simulation models are illustrated with two cancer screening models (Breast Cancer Model and Lung Cancer Policy Model) adapted to include radiation exposure effects from mammography and chest computed tomography (CT), respectively. The primary outcome projected by the breast model was life expectancy (LE) for BRCA1 mutation carriers. Digital mammographic screening beginning at ages 25, 30, 35, and 40 years was evaluated in the context of screenings with false-positive results and radiation exposure effects. The primary outcome of the lung model was lung cancer-specific mortality reduction due to annual screening, comparing two diagnostic CT protocols for lung nodule evaluation. The Metropolis-Hastings algorithm was used to estimate the mean values of the results with 95% uncertainty intervals (UIs). RESULTS: Without radiation exposure effects, the breast model indicated that annual digital mammography starting at age 25 years maximized LE (72.03 years; 95% UI: 72.01 years, 72.05 years) and had the highest number of screenings with false-positive results (2.0 per woman). When radiation effects were included, annual digital mammography beginning at age 30 years maximized LE (71.90 years; 95% UI: 71.87 years, 71.94 years) with a lower number of screenings with false-positive results (1.4 per woman). For annual chest CT screening of 50-year-old females with no follow-up for nodules smaller than 4 mm in diameter, the lung model predicted lung cancer-specific mortality reduction of 21.50% (95% UI: 20.90%, 22.10%) without radiation risk and 17.75% (95% UI: 16.97%, 18.41%) with radiation risk. CONCLUSION: Because including radiation exposure risk can influence long-term projections from simulation models, it is important to include these risks when conducting modeling-based assessments of diagnostic imaging.

The economic burden of incidentally detected findings.

Practitioners in all medical disciplines recognize the high frequency of incidentally detected findings. Although some findings are discovered on physical examination, an increasing majority are detected at imaging performed for another indication. With increasing federal scrutiny on the net value of imaging services, the costs and benefits of incidental findings need to be more rigorously quantified. In this article, the authors examine current related work on imaging expenditures for incidental findings and provide a framework for future investigations that will efficiently and substantially advance the knowledge in this field.

Treatment of renal artery in-stent restenosis with sirolimus-eluting stents.

The objective of this study was to analyze the use of sirolimus-eluting stent (SES) placement for the treatment of renal artery in-stent restenosis (RA-ISR). The optimal treatment of RA-ISR has not been fully elucidated to date. We retrospectively analyzed consecutive patients from our institution who underwent treatment of RA-ISR with a SES from May 2004 to June 2006. Using duplex ultrasound, RA-ISR (> 60% diameter) was determined by peak systolic velocity (PSV) > 300 cm/s and renal aortic ratio (RAR) > 4.0. Renal function (creatinine) and blood pressure were measured at baseline and follow-up. SESs were implanted in 16 patients (22 renal arteries) during the study period. The study cohort was predominantly female (75%) with a mean age of 68 +/- 12 years. RA-ISR was treated with SESs with a mean diameter of 3.5 mm and mean length of 17.9 +/- 3.8 mm. The mean post-dilation balloon diameter was 4.8 +/- 0.6. The baseline renal artery PSV was 445 +/- 131 cm/s with a mean RAR of 5.0 +/- 1.6. Follow-up information was available in 21 renal arteries. During a median follow-up of 12 months (range: 9-15 months), 15 renal arteries (71.4%) developed recurrence of ISR by ultrasonographic criteria. Univariate analysis revealed that female sex was an independent predictor of recurrence of ISR after SES implantation (p < 0.05). In conclusion, placement of a SES for the treatment of ISR in renal arteries is associated with high initial technical success but significant restenosis on duplex ultrasonography at follow-up.