Patients undergoing recurrent CT scans: assessing the magnitude

To assess percent of patients undergoing multiple CT exams that leads to cumulative effective dose (CED) of ≥ 100 mSv and determine their age distribution. Data was retrieved retrospectively from established radiation dose monitoring systems by setting the threshold value of 100 mSv at four institutions covering 324 hospitals. The number of patients with CED ≥ 100 mSv only from recurrent CT exams during a feasible time period between 1 and 5 years was identified. Age and gender distribution of these patients were assessed to identify the magnitude of patients in the relatively lower age group of ≤ 50 years. Of the 2.5 million (2,504,585) patients who underwent 4.8 million (4,819,661) CT exams during the period of between 1 and 5 years, a total of 33,407 (1.33%) patients received a CED of ≥ 100 mSv with an overall median CED of 130.3 mSv and maximum of 1185 mSv. Although the vast majority (72–86%) of patients are > 50 years of age, nearly 20% (13.4 to 28%) are ≤ 50 years. The minimum time to accrue 100 mSv was a single day at all four institutions, an unreported finding to date. We are in an unprecedented era, where patients undergoing multiple CT exams and receiving CED ≥ 100 mSv are not uncommon. While underscoring the need for imaging appropriateness, the consideration of the number and percent of patients with high exposures and related clinical necessities creates an urgent need for the industry to develop CT scanners and protocols with sub-mSv radiation dose, a goal that has been lingering. • We are in an era where patients undergoing multiple CT exams during a short span of 1 to 5 years are not uncommon and a sizable fraction among them are below 50 years of age. • This leads to cumulative radiation dose to individual patients at which radiation effects are of real concern. • There is an urgent need for the industry to develop CT scanners with sub-mSv radiation dose, a goal that has been lingering.     

Comparison of professional medical society guidelines for appropriate use of coronary computed tomography angiography

BackgroundMultiple appropriate use criteria (AUC) exist for the evaluation of coronary artery disease (CAD), but there is little data on the agreement between AUC from different professional medical societies. The aim of this study is to compare the appropriateness of coronary computed tomography angiography (CCTA) exams assessed using multimodality AUC from the American College of Cardiology Foundation (ACCF) versus the American College of Radiology (ACR).MethodsIn a single-center prospective cohort study from June 2014 to 2016, 1005 consecutive subjects referred for evaluation of known or suspected CAD received a contrast-enhanced CCTA. The primary outcome was the agreement of appropriateness ratings using ACCF and ACR guidelines, measured by the kappa statistic. A secondary outcome was the rate of obstructive CAD by appropriateness rating.ResultsAmong 1005 subjects, the median (5–95th percentile) age was 59 (37–76) years with 59.0% male. The ACCF criteria classified 39.6% (n = 398) appropriate, 24.2% (n = 243) maybe appropriate, and 36.2% (n = 364) rarely appropriate. The ACR guidelines classified 72.3% (n = 727) appropriate, 2.6% (n = 26) maybe appropriate, and 25.1% (n = 252) rarely appropriate. ACCF and ACR appropriateness ratings were in agreement for 55.0% (n = 553). Overall, there was poor agreement (kappa 0.27 [95% confidence interval 0.23–0.31]). By both AUC methods, a low rate of obstructive CAD was observed in the rarely appropriate exams (ACCF 7.1% [n = 26 of 364] and ACR 13.5% [n = 34 of 252]).ConclusionsCompared to ACCF criteria, the ACR guidelines of appropriateness were broader and classified significantly more CCTA exams as appropriate. The poor agreement between appropriateness ratings from the ACCF and ACR AUC guidelines evokes implications for reimbursement and future test utilization.     

Late Effects of Thoracic Irradiation in Children

Purpose:  To summarize the literature regarding the late effects of radiotherapy to the thorax in childhood and adolescence with special emphasis on cardiac and pulmonary impairment. Material and Methods:  The literature was critically reviewed using the PubMed^? database with the key words “late effects”, “late sequelae”, “child”, “childhood”, “adolescence”, “radiation”, “radiotherapy”, “thorax”, “lung”, “heart”, and “pulmonary”. Results:  17 publications dealing with radiation-induced pulmonary and cardiac late sequelae in children could be identified and were analyzed in detail. 29 further publications with additional information were also included in the analysis. Pulmonary function impairment after mediastinal irradiation arose in one third of all pediatric patients, even when treatment was performed with normofractionated lower doses (15–25 Gy). Whole lung irradiation was regularly followed by pulmonary function impairment with differing rates in several reports. However, clinically symptomatic function impairment like dyspnea was less frequent. Irradiation of up to 25 Gy (single doses ≤ 2 Gy) to the heart showed little or no cardiac toxicity in analyses of irradiated children (median follow-up 1.3–14.3 years). Doses of > 25 Gy (single doses ≤ 2–3.3 Gy) led to several cardiac dysfunctions. However, new data from adults with longer follow-up may indicate threshold doses as low as 1 Gy. Impairment of skeletal growth, breast hypoplasia, and secondary malignancy were further potential late sequelae. Conclusion:  Several retrospective reports described radiation-associated late sequelae in children. However, there is still a lack of sufficient data regarding the characterization of dose-volume effects.      

Radiology Order Decision Support: Examination-Indication Appropriateness Assessed Using 2 Electronic Systems

PurposeThe goal of the study was to determine the effects of guideline implementation strategy using 2 commercial radiology clinical decision support (CDS) systems.MethodsThe appropriateness and insurance dispositions of MRI and CT orders were evaluated using the Medicalis SmartReq and Nuance RadPort CDS systems during 2 different 3-month periods. Logistic regression was used to compare these outcomes between the 2 systems, after adjusting for patient-mix differences.ResultsApproximately 2,000 consecutive outpatient MRI and CT orders were evaluated over 2 periods of 3 months each. Medicalis scored 60% of exams as “indeterminate” (insufficient information) or “not validated” (no guidelines). Excluding these cases, Nuance scored significantly more exams as appropriate than did Medicalis (80% versus 51%, P < .001) and predicted insurance outcome significantly more often (76% versus 58%, P < .001). Only when the Medicalis “indeterminate” and “not validated” categories were combined with the high- or moderate-utility categories did the 2 CDS systems have similar performance. Overall, 19% of examinations with low-utility ratings were reimbursed. Conversely, 0.8% of examinations with high- or moderate-utility ratings were denied reimbursement.ConclusionsThe chief difference between the 2 CDS systems, and the strongest influence on outcomes, was how exams without relevant guidelines or with insufficient information were handled. Nuance augmented published guidelines with clinical best practice; Medicalis requested additional information utilizing pop-up windows. Thus, guideline implementation choices contributed to decision making and outcomes. User interface, specifically, the number of screens and completeness of indication choices, controlled CDS interactions and, coupled with guidance implementation, influenced willingness to use the CDS system.     

Spiral CT of pulmonary nodules: interobserver variation in assessment of lesion size

The aim of this study was to assess interobserver variability in size determination of pulmonary nodules at spiral CT. Twenty-three patients with known pulmonary nodules (diameter 2–40 mm, mean diameter 7 mm) underwent spiral chest CT (collimation 5 mm, pitch 1). Images were reconstructed at 3- and 5-mm intervals (RI). Hard copies were analyzed by two radiologists who recorded every nodule with regard to location, diagnostic confidence (“definite,”“probable”) and nodule size in increments of 1 mm with specific attention to correct classification into one of three size classes (≤ 5 mm, 6–10 mm, > 10 mm). Interobserver variability was determined with Pearson's correlation coefficient and k measure. Of a total of 286 nodules, 103 nodules were found accordingly by both readers at 3 mm RI, and 96 at 5 mm RI. There was a good correlation of measurements (in millimeters) between both readers (Pearson's correlation coefficient: 0.89–0.95). Interobserver variability in categories was good at both reconstruction intervals (k: 0.61 at 3 mm, 0.74 at 5 mm RI) and very good (0.81) at 5 mm RI when uncertain nodules were excluded. Spiral CT allows reproducible size determination of pulmonary nodules as shown by good interobserver agreement in exact size measurement and categorization into three size classes. Received: 2 September 1999; Revised: 24 January 2000; Accepted: 27 January 2000     

Evaluation of automated attenuation-based tube current adaptation for coronary calcium scoring in MDCT in a cohort of 262 patients

The aim of our study was to evaluate attenuation-based tube current adaptation in coronary calcium scoring using ECG-gated multi-detector-row CT (MDCT). A total of 262 patients underwent non-enhanced cardiac MDCT. Group 1 was scanned using a standard protocol with 120 kV and 150 mAs_eff. Groups 2–4 were scanned using an attenuation-based dose-adaptation template (CARE Dose) with different effective reference mAs settings (150, 180, 210 mAs_eff). Body-mass index (BMI) and CT-dose index values were calculated for each patient. Image noise and subjective image quality were assessed. Regression analysis was performed, and the variation coefficient of image noise was determined. Compared to the standard scan protocol a dose reduction of 31.1% for group 2 and 20.1% for group 3 was observed. Measurement variation of image noise was smaller for the attenuation-based dose adaptation protocols (group 2–4) (16.2–17.1%) compared to the standard scan protocol (32.3%). Regression analysis of groups 2–4 showed better correlation with improved dose usage based on BMI (all P ≤ 0.001). Median image quality was “excellent” in groups 2–4 and “good” in group 1. Automated attenuation-based tube current adaptation in coronary calcium scoring is technically feasible, can decrease patient dose, and reduces variation in image noise as a sign of improved dose usage. The study was supported by a START grant from the University Hospital of Aachen, Germany.     

Conventional diagnostic imaging of the temporal bone. A historical review

Summary The Viennese Medical School played an important role in the development of radiological examinations and signs of the temporal bone with conventional X-rays. Famous pioneers include E. G. Mayer (1893–1969) and L. Psenner (1910–1986). Nowadays conventional X-rays and tomography have lost their important role in diagnostic radiology of the temporal bone, but the basic principles established in those early years of radiology are still used now. This statement is correct not only for conventional X-rays, but particularly for “poly”-tomography in comparison with CT.      

White matter changes on magnetic resonance imaging following whole-brain radiotherapy for brain metastases

Purpose The purpose of this study was to evaluate white matter (WM) abnormalities induced by WBRT. Materials and methods Twenty-four patients (11 men and 13 women; age range 38–74 years, median 60 years) who survived for more than 1 year after completion of WBRT (radiation dose range 30–40 Gy, median 35 Gy) at our institution between January 2000 and June 2003 were followed up with magnetic resonance (MR) scans for 11–51 months (median 19 months). We evaluated WM changes attributable to WBRT as grade 0–6 and assessed possible contributing factors by statistical analysis. Results WM changes were found in 20 patients: Eight were assessed as grade 2, three as grade 3, and nine as grade 5. In total, 12 patients developed grade 3 or higher WM changes. Age (<60 vs ≥60 years), sex, radiation dose (≤35 vs >35 Gy), chemotherapy (with CDDP vs without CDDP), biologically effective dose (≤120 vs >120 Gy1), and head width (<16.3 vs ≥16.3 cm) were found not to be relevant to the incidence or severity of the WM changes. Conclusion Long-term survivors who have under-gone WBRT may have a higher incidence of WM abnormalities.     

Clinical demand for chest/abdomen/pelvis anatomy following thoracic or lumbar spine CT

The purpose of this study is to determine how often CT is repeated to obtain chest/abdomen/pelvis data outside the reconstructed field of view (FOV) on a prior spine CT. Radiology records of 1,239 consecutive thoracic and lumbar spine CT exams of 1,025 patients from January 1, 2006 to December 31, 2008 were retrospectively reviewed to identify patients who subsequently had CT studies of the chest, abdomen, and/or pelvis. The CT data were also evaluated for contrast enhancement, slice thickness, radiation dose, and reason for subsequent CT exam. Over 3 years, 290 of the 1,239 (24%) spine CT exams were followed by CT of the same anatomic region to evaluate extraspinal anatomy. The use or nonuse of contrast in these follow-up studies was the same as the preceding spine study in 91 cases, which were repeated on the same day (n?=?37), within 7 days (n?=?19), within 8-30 days (n?=?15), or after 30 days (n?=?20). Fourteen of 25 (56%) T spine CTs and 34 of 52 (65%) L spine CTs without contrast were followed by a chest CT or abdomen/pelvis CT without contrast within 7 days, respectively. Among 31 pediatric exams, 6 of 31 (19%) spine CTs were followed by a CT of the same anatomic region, all within 7 days. Reconstructing full FOV images of spine CT scans in addition to the standard coned down spine FOV may reduce redundant CT imaging and radiation dose.     

Comparison of deep learning,radiomics and subjective assessment of chest CT findings in SARS-CoV-2 pneumonia

PurposeComparison of deep learning algorithm, radiomics and subjective assessment of chest CT for predicting outcome (death or recovery) and intensive care unit (ICU) admission in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.MethodsThe multicenter, ethical committee-approved, retrospective study included non-contrast-enhanced chest CT of 221 SARS-CoV-2 positive patients from Italy (n = 196 patients; mean age 64 ± 16 years) and Denmark (n = 25; mean age 69 ± 13 years). A thoracic radiologist graded presence, type and extent of pulmonary opacities and severity of motion artifacts in each lung lobe on all chest CTs. Thin-section CT images were processed with CT Pneumonia Analysis Prototype (Siemens Healthineers) which yielded segmentation masks from a deep learning (DL) algorithm to derive features of lung abnormalities such as opacity scores, mean HU, as well as volume and percentage of all-attenuation and high-attenuation (opacities >−200 HU) opacities. Separately, whole lung radiomics were obtained for all CT exams. Analysis of variance and multiple logistic regression were performed for data analysis.ResultsModerate to severe respiratory motion artifacts affected nearly one-quarter of chest CTs in patients. Subjective severity assessment, DL-based features and radiomics predicted patient outcome (AUC 0.76 vs AUC 0.88 vs AUC 0.83) and need for ICU admission (AUC 0.77 vs AUC 0.0.80 vs 0.82). Excluding chest CT with motion artifacts, the performance of DL-based and radiomics features improve for predicting ICU admission.ConclusionDL-based and radiomics features of pulmonary opacities from chest CT were superior to subjective assessment for differentiating patients with favorable and adverse outcomes.     

Pediatric CT scan usage in Japan: results of a hospital survey

Purpose The aim of this study was to examine the usage parameters of diagnostic computed tomography (CT) in children because of concerns of possible overuse in Japanese hospitals, including the “technical” CT exposure settings and the “clinical” grounds for CT requests. Materials and methods We examined the methodology at the radiology department to reduce radiation exposure to children and performed a retrospective study on pediatric CT requests during a 1-year period at Nagasaki University Hospital. The parameters of diagnostic CT usage for minor head trauma and acute appendicitis were studied in detail. Results CT radiation dose settings are adjusted for children based on guidelines issued by the Japan Radiological Society, with few limitations. CT requests were made for 62% of minor head trauma cases and 76% of cases clinically suspected to be acute appendicitis. These figures are considerably higher than those reported by studies in the United Kingdom, Canada, or the United States. No specific guidelines are advocated regarding CT usage for minor head trauma. The diagnosis of acute appendicitis in children is almost routinely referred for “confirmation” by CT. Conclusion CT radiation risks to children at Japanese hospitals need to be considered more seriously. Physicians should be encouraged to follow diagnostic algorithms that help avoid unnecessary CT usage in children.     

Interpretation of head CT scans in the emergency department by fellows versus general staff non-neuroradiologists: a closer look at the effectiveness of a quality control program

Prior studies have evaluated discordance rates among radiology residents in interpretation of head computed tomograms (CTs). To our knowledge, there has been no study to compare performance among first-year fellows and more experienced general staff radiologists. This study will compare performances of these groups and evaluate the effect of a redundant system as part of a quality control program. Retrospective review of 3,886 consecutive head CTs in the Emergency Department from 7/01/04 to 6/30/2005 was performed. Fellows interpreted 2,150 and general staff radiologists 1,736 cases. Staff radiologist mean experience was 4 years (2–10 years). All primary interpretations were over-read by staff neuroradiologists (>10 years experience) as quality control. Discrepancies were divided into “major discordance” and “minor discordance.” Major discordance is defined as a misread occurred that potentially delayed clinical management and thus may have incurred in mortality or disability. Minor discordance is defined as if there was no change in clinical management or impact on the patient’s outcome. The patient electronic medical records were obtained and retrospectively reviewed to identify if there was an acute change in clinical management. Overall discordance rate of both groups was 2.7% (103/3,886), 0.3% major false negative (10/3,886), 1.7% minor false negative (65/3,886), 0.4% false positive (15/3,886). Fellows overall discordance rate was 2.6% (55/2,150) with major false negatives 4/2,150 (0.2%) and 2.8% (48/1,736) for general staff radiologists with 6/1736 (0.3%) major false negatives, p values 0.69 and 0.14, respectively. Three out of ten major false negatives were confirmed with the quality assurance interpretation on follow-up studies; four cases were in agreement with initial interpretation. Performance among first-year fellows and general staff radiologists in interpretation of head CTs was highly accurate (97.3%) without statistically significant difference between the groups. The overall relatively low discrepant rate between fellowship trainees and generalist staffs, as well as the negligible change in clinical management, suggests little utility in over-reads of head CT scans by the neuroradiology service as part of a year-round quality control program. However, because of a relative high discrepant rate in the early months of fellowship training (>5%) in our study, it may be wise to implement a quality assurance program in the first few months to improve patient care. Increasing over-reading rate may reduce false negative rate, as the overall false positive rate is relatively low (<0.5%).     

Yield of head CT in the alcohol-intoxicated patient in the emergency department

We aimed to determine the yield of positive head computed tomography (CT) findings among suspected alcohol-intoxicated patients presenting to the emergency department (ED). Our secondary aim was to determine if elderly intoxicated patients were more likely to have an intracranial injury. We identified patients suspected of alcohol intoxication who underwent CT scanning in the ED over a 4-year period. Pre-determined data elements including demographics, diagnosis, and disposition were extracted using a pre-formatted data sheet by blinded abstractors. “Positive” CT was defined as evidence of any type of intracranial hemorrhage. A total of 2,671 subjects with suspected alcohol intoxication and a head CT were identified. Fifty out of the 2,671 (1.9%) had a positive CT. Among CT scans of elderly (≥60 years of age) subjects, 15/555 (2.7%, 95% CI = 1.4–4.1%) were positive compared with 35/2,116 (1.7%, 95% CI = 1.1–2.2%) among those <60 years of age (p = 0.11). The yield of positive head CT among alcohol-intoxicated patients was low, at 1.9%. An age cutoff of 60 years in this population did not predict a significantly higher positive rate.     

Detection of ventricular shunt malfunction in the ED: relative utility of radiography,CT, and nuclear imaging

The study objective was to determine the relative diagnostic utility of the radiographic shunt series (SS), head computed tomography (CT), and nuclear imaging performed in our Emergency Department (ED) for evaluating ventricular shunt malfunction. We retrospectively reviewed medical records, head CT (if performed), and nuclear imaging (if performed) for all ED patients with suspected shunt malfunction from 2002 to 2007 who underwent plain film shunt evaluation (296 cases/186 individuals) to determine if surgical shunt revision was performed. Logistic regression analysis was applied. Four percent (12/296) of radiographic SS were abnormal. Only 0.3% (1/296) underwent surgical revision in the absence of an abnormal head CT or nuclear imaging. Eighteen percent (51/282) of head CT exams were positive and 19% (24/128) of nuclear imaging exams were positive for shunt malfunction. Twenty-three percent (67/296) underwent surgical shunt revisions. Statistical analysis demonstrated that SS evaluation was not significantly associated with surgical shunt revision (OR 0.92; 95% CI, 0.7–1.2; p = 0.47). Head CT demonstrated a significant association with surgical revision (OR 1.4; 95% CI, 1.2–1.5; p < 0.001), as did nuclear imaging (OR 1.4; 95% CI, 1.2–1.6; p < 0.001). Patients with suspected ventricular shunt malfunction frequently require surgical revision. Abnormal radiographic SS was not associated with progression to surgical shunt revision, whereas abnormal head CT and abnormal nuclear imaging were significantly associated with surgical revision. We conclude that radiographic SS in the ED is of low diagnostic utility and that patients with suspected shunt malfunction should instead initially undergo CT and/or nuclear imaging.     

“Air bubble”: a new diagnostic CT sign of perforated pulmonary hydatid cyst

The greatest difficulty in the CT diagnosis of perforated pulmonary hydatid cyst (PPHC) is the increase in the attenuation numbers following infection. Because of the solid density of infected hydatid cysts, the differentiation from an abscess or neoplasm is usually impossible. The aim of this study was to evaluate the value of “air bubble” as a new CT sign in the diagnosis of PPHC. Sixty-five patients (28 men and 37 women) with PPHC were included in the study. As a control group, 55 patients who had malignant (n = 36) or non-malignant (n = 19) pulmonary diseases were also examined. Radiological diagnosis with classical CT findings was made in only 38 of 65 patients (58.5 %) with PPHC. Air bubble sign was positive in 54 of the patients with PPHC (sensitivity 83.1 %) but only 3 of 55 patients in control group (specificity 94.5 %). When we analyzed the CT scans with classical CT findings including air bubble, the diagnosis of PPHC was made in 61 of patients (93.8 %). It is concluded that “air bubble sign” is a valuable CT finding in the diagnosis of PPHC. Received: 3 September 1997; Revision received: 22 May 1998; Accepted: 5 August 1998     

Radiofrequency Ablation of Colorectal Liver Metastases: Small Size Favorably Predicts Technique Effectiveness and Survival

The objective of this study was to analyze long-term results of radiofrequency thermal ablation (RFA) for colorectal metastases (MTS), in order to evaluate predictors for adverse events, technique effectiveness, and survival. One hundred ninety-nine nonresectable MTS (0.5–8 cm; mean, 2.9 cm) in 122 patients underwent a total of 166 RFA sessions, percutaneously or during surgery. The technique was “simple” or “combined” with vascular occlusion. The mean follow-up time was 24.2 months. Complications, technique effectiveness, and survival rates were statistically analyzed. Adverse events occurred in 8.1% of lesions (major complication rate: 1.1%), 7.1% with simple and 16.7% with combined technique (p = 0.15). Early complete response was obtained in 151 lesions (81.2%), but 49 lesions (26.3%) recurred locally after a mean of 10.4 months. Sustained complete ablation was achieved in 66.7% of lesions ≤3 cm versus 33.3% of lesions >3 cm (p < 0.0001). Survival rates at 1, 3, and 5 years were 91%, 54%, and 33%, respectively, from the diagnosis of MTS and 79%, 38%, and 22%, respectively, from RFA. Mean survival time from RFA was 31.5 months, 36.2 in patients with main MTS ≤3 cm and 23.2 in those with at least one lesion >3 cm (p = 0.006). We conclude that “simple” RFA is safe and successful for MTS ≤3 cm, contributing to prolong survival when patients can be completely treated. Presented at CIRSE 2006.     

Repeated sinus CT imaging after recent head imaging

ObjectivesExcessive use of sinus CT is a significant problem in medical imaging, resulting in unnecessary costs and radiation exposure. This study assesses frequency of sinus CT performed after recent head imaging has already adequately evaluated the sinuses.MethodsA retrospective search of the PACS database of an academic medical center was performed to identify cases of sinus CT imaging in 2017. Cases were excluded if sinus CT was performed related to trauma, tumor, operative evaluation, or acute infection other than sinusitis (orbital cellulitis, intracranial abscess). Studies with separate imaging covering the sinuses ordered at the same time as sinus CT or performed previously within 4 weeks were identified and clinical information was recorded.ResultsOf 735 sinus CTs performed, 19 (5%) had same-day head imaging and 30 (8%) had previous head imaging within 4 weeks, adding up to a cumulative 13% of cases with recent head imaging. The average patient age was 42, with 13 pediatric cases. Of ordering providers, residents ordered the highest percentage of sinus CTs with same-day head imaging (84%) and previous imaging within 4 weeks (63%). The sinuses were described in all head CT radiology reports, while 10 of 12 brain MRI reports did not mention the sinuses.ConclusionIn one year, 13% of patients receiving sinus CTs at our institution had recent head imaging. A focused education effort for ordering providers to avoid repeating sinus imaging, and for radiology to comment on sinuses on head imaging, may reduce unnecessary sinus CTs.     

Dots are not clots: the over-diagnosis and over-treatment of PE

The purpose of this work is to question the conventional theory that all pulmonary emboli (PE) are abnormal, and to test the hypothesis that small peripheral PE are a function of life. Most radiologists report any filling defect, independent of size, as clinically significant PE when detected in the pulmonary arteries. We sought to reinforce the theory that small dots in the pulmonary arteries are not clinically significant clots in the conventional setting. The necessity for anticoagulation should be balanced against the risk of bleeding. This retrospective HIPAA-compliant study was approved by the institutional review board; informed consent was not required. All patients diagnosed with PE by 16-slice or 64-slice multidetector computed tomography (CT) over a 6-month period who also had a lower extremity venous ultrasound (US) performed within 7 days of CT were identified. The study group included 26 women and 24 men (mean, 56 years; range, 21–90 years). The locations of the PE were plotted on a pulmonary arterial diagram, and width of the most proximal clot for each patient was measured. Of 1,273 consecutive CT studies, 101 were positive (7.9%) and 50 patients underwent lower extremity US. Thirty-three (66%) patients had PE in the central pulmonary arteries, of which 19 (58%) had deep vein thrombosis (DVT). Seventeen (34%) patients had peripheral PE; DVT was detected in 0 (0%) patients. The peripheral clots measured 1.0–3.8 mm (mean, 2.5 mm). These clots appeared focal and rounded with a “dot-like” appearance. Peripheral, focal filling defects in the pulmonary arteries, which we termed “dots,” are not traditional embolic clots, are not associated with detectable lower-extremity clot load, and may represent “normal” embolic activity originating from the lower extremity venous valves. We suggest that more in-depth understanding about small peripheral PE is needed. The necessity of conventional anticoagulation should be critically reviewed in patients with subsegmental PE and minimal clot burden.     

Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients

The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without β-blockers using the following parameters: (1) collimation: 32×0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., “morphologic scans”) and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., “functional scans”). The mean heart rate was 73 bpm (range: 42–120) and the mean scan time was 18.11±2.67 s (range: 10–27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n=4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n=6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88–97%). For these 124 examinations, the mean RVEF was 46.10% (±9.5; range: 20–72) and the mean LVEF was 58.23% (±10.88; range: 20–83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end-diastolic ventricular volumes. The mean (±SD) DLP value of the examinations was 279.86 (±117.50) mGy.cm. Assessment of underlying respiratory disease and cardiac function from the same data set was achievable in 92% of the patients with ECG-gated 64-slice MDCT.     

Appropriateness of Computed Tomography and Ultrasound for Abdominal Complaints in the Emergency Department

ObjectiveThe purpose of this study was to evaluate the appropriateness of ultrasound (US) and computed tomography (CT) examinations ordered in the emergency department (ED) for abdominal complaints.Materials and MethodsWe reviewed 154 CTs and 154 US orders for appropriateness using evidence-based recommendations by the American College of Radiology. The sample was powered to show a prevalence of inappropriate orders of 25% with a margin of error of 7.5%. Findings in the final reports were compared to the initial clinical diagnosis classified in 4 categories: normal, compatible with initial diagnosis, alternative diagnosis, and inconclusive. We also evaluated the frequency in which a second imaging modality was ordered on the same visit.ResultsA total of 135 CT and 143 US examinations had complete clinical information to allow evaluation of order appropriateness. The rate of inappropriate orders was 36.3% for CT and 84.4% for US. The final report of appropriate orders was significantly more likely to demonstrate findings compatible with the initial diagnosis for both CT (76.7% vs 20.4%, P < 0.0001) and US (38.9% vs 14.4%, P = 0.0093). Inappropriately ordered CT scans were more likely to show no abnormalities (46.9 vs 16.3%, P = 0.0001). An additional imaging order with a secondary modality was requested in 20% of the inappropriate US orders, and 8.2% of the inappropriate CT orders.ConclusionThe prevalence of inappropriate examinations in the ED was 36.3% for CT and 84.4% for US. Appropriately ordered exams were more likely to yield imaging findings compatible with the initial diagnosis for both modalities.