Validation and clinical impact of novel pericoronary adipose tissue measurement on ECG-gated non-contrast chest CT.

BACKGROUND AND AIMS: We aimed to develop a method for quantifying pericoronary adipose tissue (PCAT) on electrocardiogram (ECG)-gated non-contrast CT (NC-PCAT) and validate its efficacy and prognostic value. METHODS: We retrospectively studied two independent cohorts. PCAT was quantified conventionally. NC-PCAT was defined as the mean CT value of epicardial fat tissue adjacent to right coronary artery ostium on ECG-gated non-contrast CT. In cohort 1 (n = 300), we evaluated the correlation of two methods and the association between NC-PCAT and CT-verified high-risk plaque (HRP). We dichotomized cohort 2 (n = 333) by the median of NC-PCAT, and assessed the prognostic value of NC-PCAT for primary endpoint (all-cause death and non-fatal myocardial infarction) by Cox regression analysis. The median duration of follow-up was 2.9 years. RESULTS: NC-PCAT was correlated with PCAT (r = 0.68, p<0.0001). In multivariable logistic regression analysis, high NC-PCAT (OR:1.06; 95%CI:1.03-1.10; p = 0.0001), coronary artery calcium score (CACS) (OR:1.01 per 10 CACS increase, 95%CI:1.00-1.02; p = 0.013), and current smoking (OR:2.58; 95%CI:1.03-6.49; p = 0.044) were independent predictors of HRP. Among patients with CACS>0 (n = 193), NC-PCAT (OR:1.06; 95%CI:1.03-1.10; p = 0.0002), current smoking (OR:3.02; 95%CI:1.17-7.82; p = 0.027), and male sex (OR:2.81; 95%CI:1.06-7.48; p = 0.028) were independent predictors of HRP, whereas CACS was not (p = 0.15). Multivariable Cox regression analysis revealed high NC-PCAT as an independent predictor of the primary endpoint, even after adjustment for sex and age (HR:4.3; 95%CI:1.2-15.2; p = 0.012). CONCLUSIONS: There was a positive correlation between NC-PCAT and PCAT, with high NC-PCAT significantly associated with worse clinical outcome (independent of CACS) as well as presence of HRP.

Development and Validation of a Modified Three-Dimensional U-Net Deep-Learning Model for Automated Detection of Lung Nodules on Chest CT Images From the Lung Image Database Consortium and Japanese Datasets.

RATIONALE AND OBJECTIVES: A more accurate lung nodule detection algorithm is needed. We developed a modified three-dimensional (3D) U-net deep-learning model for the automated detection of lung nodules on chest CT images. The purpose of this study was to evaluate the accuracy of the developed modified 3D U-net deep-learning model. MATERIALS AND METHODS: In this Health Insurance Portability and Accountability Act-compliant, Institutional Review Board-approved retrospective study, the 3D U-net based deep-learning model was trained using the Lung Image Database Consortium and Image Database Resource Initiative dataset. For internal model validation, we used 89 chest CT scans that were not used for model training. For external model validation, we used 450 chest CT scans taken at an urban university hospital in Japan. Each case included at least one nodule of >5 mm identified by an experienced radiologist. We evaluated model accuracy using the competition performance metric (CPM) (average sensitivity at 1/8, 1/4, 1/2, 1, 2, 4, and 8 false-positives per scan). The 95% confidence interval (CI) was computed by bootstrapping 1000 times. RESULTS: In the internal validation, the CPM was 94.7% (95% CI: 89.1%-98.6%). In the external validation, the CPM was 83.3% (95% CI: 79.4%-86.1%). CONCLUSION: The modified 3D U-net deep-learning model showed high performance in both internal and external validation.

Large hospital variation in the utilization of Post-procedural CT to detect pulmonary embolism/Deep Vein Thrombosis in Patients Undergoing Total Knee or Hip Replacement Surgery: Japanese Nationwide Diagnosis Procedure Combination Database Study.

OBJECTIVE: The purpose of the study was to investigate variation in the use of in-hospital CT for venous thromboembolism (VTE) detection after total knee or hip replacement (TKR/THR) among surgical patients, using a nationwide Japanese in-hospital administrative database. METHODS: This retrospective study using a national administrative database (4/2012-3/2013) extracted patients who underwent TKR/THR surgeries at hospitals meeting the annual case-volume threshold of ≥ 30. Hospitals were categorized into three equally sized groups by frequency of postoperative CT use (low, middle, and high CT use group) to compare baseline patient-level and hospital-level characteristics. To further investigate between-hospital variation in CT usage, we fitted a hierarchical logistic regression model including hospital-specific random intercepts and fixed patient- and hospital-level effects. The intra class correlation coefficient was used to measure the amount of variability in CT use attributable to between-hospital variation. RESULTS: A total of 39,127 patients discharged from 447 hospitals met the inclusion criteria. The median hospital stay was 25 days (interquartile range, 20 - 32) and 7,599 (19.4%) patients underwent CT for VTE. CT utilization varied greatly among the hospitals; the crude frequency ranged from 0 to 100 % (median, 7.3 %; interquartile range, 1.8 - 18.3 %). After adjustment for known hospital- and patient-level factors related to CT use, 47 % of the variation in CT use remained attributable to the behavior of individual hospitals. CONCLUSION: We observed large inter hospital variability in the utilization of post-procedure CT for VTE detection in this Japanese TKR/THR cohort, suggesting that CT utilization is not optimized across the nation. ADVANCES IN KNOWLEDGE: We observed significant variability in the utilization of post-procedure CT for VTE detection among inpatients who underwent TKR/THR surgeries in a large sample of Japanese hospitals. The large variation suggests that CT utilization is not optimized across the nation, and that there may be potential overutilization of the technology in the highest CT use hospitals.

The usefulness of low radiation dose subtraction coronary computed tomography angiography for patients with calcification using 320-row area detector CT.

BACKGROUND: Although subtraction coronary computed tomography angiography (S-CCTA) has recently been developed to improve the diagnostic ability in patients with severe calcification, increase in radiation exposure remains a concern. The usefulness of S-CCTA using a low-radiation dose protocol was investigated. METHODS: S-CCTA in 320-row area detector CT was performed on 84 consecutive patients with suspected obstructive coronary artery disease with Agatston score ≥100. Reconstruction and radiation dose were changed according to the slow filling time (SF) (137.5ms

Feasibility of dynamic myocardial CT perfusion using single-source 64-row CT.

BACKGROUND: Dynamic myocardial computed tomography perfusion (CTP) is an emerging technique to diagnose significant coronary stenosis. However, this procedure has not been reported using single-source 64-row CT. OBJECTIVE: To investigate the radiation dose and the diagnostic performance of dynamic CTP to diagnose significant stenosis by catheter exam. METHODS: We prospectively included 165 patients who underwent CTP exam under adenosine stress using a single-source 64-row CT. MBF was calculated using the deconvolution technique. Quantitative perfusion ratio (QPR) was defined as the myocardial blood flow (MBF) of the myocardium with coronary stenosis divided by the MBF of the myocardium without significant stenosis or infarct. Of the 44 patients who underwent subsequent coronary angiography, we assessed the diagnostic performance to diagnose ≥50% stenosis by quantitative coronary analysis (QCA). RESULTS: The average effective dose of dynamic CTP and the entire scans were 2.5 ±â€¯0.7 and 7.3 ±â€¯1.8 mSv, respectively. The MBF of the myocardium without significant stenosis was 1.20 ±â€¯0.32 ml/min/g, which significantly decreased to 0.98 ±â€¯0.24 ml/min/g (p < 0.01) in the area with ≥50% stenosis by CT angiography. The QPR of the myocardium with QCA ≥50% stenosis was significantly lower than 1 (0.84 ±â€¯0.32, 95% confidence interval (CI), 0.77-0.90, p < 0.001). The accuracy to detect QCA ≥50% stenosis was 82% (95%CI, 74-88%) using CT angiography alone and significantly increased to 87% (95%CI, 80-92%, p < 0.05) including QPR. CONCLUSION: Dynamic myocardial CTP could be performed using 64-row CT with a low radiation dose and would improve the diagnostic performance to detect QCA ≥50% stenosis than CT angiography alone.

Submillisievert imaging protocol using full reconstruction and advanced patient motion correction in 320-row area detector coronary CT angiography.

Radiation exposure remains a concern in the use of coronary CT angiography (CCTA). Full reconstruction (Full) and reconstruction using advanced patient motion correction (APMC) could obtain a lower radiation dose using low tube current scanning in a 320-row Area Detector CT (320-ADCT). The radiation dose for an imaging protocol using Full and APMC in daily practice was estimated. A total of 209 patients who underwent CCTA in 1 rotation scanning with 100 kv and adaptive iterative dose reduction 3D in 320-ADCT were enrolled. Imaging protocols were classified into 3 groups based on estimated slow filling time: (1) slow filling time ≥ 275 msec, Full with 30% of usual tube current (N = 43)(Full30%mA) (2) 206.3 msec ≤ slow filling time < 275 msec, APMC with 50% of usual tube current (N = 48)(APMC50%mA); and (3) 137.5 msec ≤ slow filling time < 206.3 msec, Half reconstruction with usual tube current (N = 118)(Half100%mA). Radiation dose was estimated by the effective dose. The diagnostic accuracy of CCTA was compared with that of invasive coronary angiography in 28 patients. The effective doses of Full30%mA, APMC50%mA, and Half100%mA were 0.77 ± 0.31, 1.30 ± 0.85, and 1.98 ± 0.68, respectively. Of 28 patients, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value in vessel-based analyses were: Full30%mA, 66.7, 82.4, 80.0, 40.0, and 93.3%; APMC50%mA, 100.0, 80.0, 83.3, 50.05, and 100.0%; and Half100%mA, 90.9, 83.0, 86.3, 78.95, and 92.9%, respectively. An imaging protocol using Full30%mA and APMC50%mA was one of the methods how radiation dose could be reduced radiation dose maintained diagnostic accuracy compared to imaging using conventional Half100%mA.

Slice-accelerated gradient-echo echo planar imaging dynamic susceptibility contrast-enhanced MRI with blipped CAIPI: effect of increasing temporal resolution.

PURPOSE: To assess the influence of high temporal resolution on the perfusion measurements and image quality of perfusion maps, by applying simultaneous-multi-slice acquisition (SMS) dynamic susceptibility contrast-enhanced (DSC) magnetic resonance imaging (MRI). MATERIALS AND METHODS: DSC-MRI data using SMS gradient-echo echo planar imaging sequences in 10 subjects with no intracranial abnormalities were retrospectively analyzed. Three additional data sets with temporal resolution of 1.0, 1.5, and 2.0 s were created from the raw data sets of 0.5 s. Cerebral blood flow (CBF), cerebral blood volume, mean transit time (MTT), time to peak (TTP), and time to maximum tissue residue function (T max) measurements were performed, as was visual perfusion map analysis. The perfusion parameter for temporal resolution of 0.5 s (reference) was compared with each synthesized perfusion parameter. RESULTS: CBF, MTT, and TTP values at temporal resolutions of 1.5 and 2.0 s differed significantly from the reference. The image quality of MTT, TTP, and T max maps deteriorated with decreasing temporal resolution. CONCLUSION: The temporal resolution of DSC-MRI influences perfusion parameters and SMS DSC-MRI provides better image quality for MTT, TTP, and T max maps.

Appropriate imaging utilization in Japan: a survey of accredited radiology training hospitals.

PURPOSE: To survey whether imaging is being performed appropriately in Japan, and to survey whether radiologists intervene to ensure imaging requests are appropriate. METHODS: An online survey was sent to radiologists at accredited radiology training hospitals. The survey included the radiologists' perspectives on whether imaging is performed appropriately at their institutions and whether they intervene if the indication for imaging is inappropriate/ambiguous. RESULTS: The response rate was 87.3% (165/189). We observed marked variability in the frequencies that imaging not recommended by the guidelines was performed among modalities and/or body parts; the responses "very frequently/frequently performed" were more common for breast cancer related imaging examinations and for head CT/MRI. The respondents frequently reported that inappropriate/ambiguous indications included requests to expand the craniocaudal range or to perform whole-body imaging. In 80% of the hospitals (132/165), radiologists contacted the physicians who requested unrecommended examinations; the number of CT and MRI examinations that full-time radiologists need to interpret in a half-day session was significantly smaller at these hospitals (median 18 vs 24, P = 0.032). CONCLUSION: We conducted a survey to investigate appropriate imaging utilization in Japan. At the hospitals with numerous examinations to interpret, full-time radiologists may find it difficult to ensure that examinations are ordered appropriately.

CT pulmonary angiography-based scoring system to predict the prognosis of acute pulmonary embolism.

BACKGROUND: The purpose is to develop a comprehensive risk-scoring system based on CT findings for predicting 30-day mortality after acute pulmonary embolism (PE), and to compare it with PE Severity Index (PESI). MATERIALS AND METHODS: The study included consecutive 1698 CT pulmonary angiograms (CTPA) positive for acute PE performed at a single institution (2003-2010). Two radiologists independently assessed each study regarding clinically relevant findings and then performed adjudication. These variables plus patient clinical information were included to build a LASSO logistic regression model to predict 30-day mortality. A point score for each significant variable was generated based on the final model. PESI score was calculated in 568 patients who visited the hospital after 2007. RESULTS: Inter-reader agreements of interpretations were >95% except for septal bowing (92%). The final prediction model showed superior ability over PESI (AUC = 0.822 vs 0.745) for predicting all-cause 30-day mortality (12.4%). The scoring system based on the significant variables (age (years), pleural effusion (+20), pericardial effusion (+20), lung/liver/bone lesions suggesting malignancy (+60), chronic interstitial lung disease (+20), enlarged lymph node in thorax (+20), and ascites (+40)) stratified patients into 4 severity categories, with mortality rates of 0.008% in class-I (≤50 pt), 3.8% in class-II (51-100 pt), 17.6% in class-III (101-150 pt), and 40.9% in class-IV (>150 pt). The mortality rate in the CTPA-high risk category (class-IV) was higher than those in the PESI's high risk (27.4%) and very high risk (25.2%) categories. CONCLUSION: The CTPA-based model was superior to PESI in predicting 30-day mortality. Incorporating the CTPA-based scoring system into image interpretation workflows may help physicians to select the most appropriate management approach for individual patients.

Limited Hospital Variation in the Use and Yield of CT for Pulmonary Embolism in Patients Undergoing Total Hip or Total Knee Replacement Surgery.

Purpose To evaluate the variation among U.S. hospitals in overall use and yield of in-hospital computed tomographic (CT) pulmonary angiography (PA) in patients undergoing total hip replacement (THR) or total knee replacement (TKR) surgery. Materials and Methods Patients in the Premier Research Database who underwent elective TKR or THR between 2007 and 2011 were enrolled in this HIPAA-compliant, institutional review board-approved retrospective observational study. The informed consent requirement was waived. Hospitals were categorized into low, medium, and high tertiles of CT PA use to compare baseline patient- and hospital-level characteristics and pulmonary embolism (PE) positivity rates. To further investigate between-hospital variation in CT PA use, a hierarchical logistic regression model that included hospital-specific random effects and fixed patient- and hospital-level effects was used. The intraclass correlation coefficient (ICC) was used to measure the amount of variability in CT PA use attributable to between-hospital variation. Results The cohort included 205 198 patients discharged from 178 hospitals (median of 734.5 patients discharged per hospital; interquartile range, 316-1461 patients) with 3647 CT PA studies (1.8%). The crude frequency of CT PA scans among the hospitals ranged from 0% to 6.2% (median, 1.6%); more than 90% of the hospitals performed CT PA in less than 3% of their patients. The mean hospital-level PE positivity rate was 12.3% (median, 9.1%); there was no significant difference in PE positivity rate across low through high CT PA use tertiles (11.3%, 11.9%, 12.9%, P = .37). After adjustment for hospital- and patient-level factors, the remaining amount of interhospital variation was relatively low (ICC, 9.0%). Conclusion Limited interhospital variation in use and yield of in-hospital CT PA was observed among patients undergoing TKR or THR in the United States. © RSNA, 2016 Online supplemental material is available for this article.

Normal ventricular diameter ratio on CT provides adequate assessment for critical right ventricular strain among patients with acute pulmonary embolism.

There is variability in guideline recommendations for assessment of the right ventricle (RV) with imaging as prognostic information after acute pulmonary embolism (PE). The objective of this study is to identify a clinical scenario for which normal CT-derived right-to-left ventricular (RV/LV) ratio is sufficient to exclude RV strain or PE-related short-term death. This retrospective cohort study included 579 consecutive subjects (08/2003-03/2010) diagnosed with acute PE with normal CT-RV/LV ratio (<0.9), 236 of whom received subsequent echocardiography. To identify a clinical scenario for which CT-RV/LV ratio was considered sufficient to exclude RV strain or PE-related short-term death, a multivariable logistic model was created to detect factors related to subjects for whom subsequent echocardiography detected RV strain or those who did not receive echocardiography and died of PE within 14 days (n = 55). The final model included five variables (c-statistic = 0.758, over-fitting bias = 2.52 %): congestive heart failure (adjusted odds ratio, OR 4.32, 95 % confidence interval, CI 1.88-9.92), RV diameter on CT >45 mm (OR 3.07, 95 % CI 1.56-6.03), age >60 years (OR 2.59, 95 % CI 1.41-4.77), central embolus (OR 1.96, 95 % CI 1.01-3.79), and stage-IV cancer (OR 1.94, 95 % CI 0.99-3.78). If these five factors were all absent (37.1 % of the population), the probability that "CT-RV/LV ratio is sufficient to exclude RV strain/PE-related short-term death" was 0.97 (95 % CI = 0.95-0.99). Normal CT-RV/LV ratio plus readily obtained five clinical predictors were adequate to exclude RV strain or PE-related short-term mortality.

A strategy to optimize radiation exposure for non-contrast head CT: comparison with the Japanese diagnostic reference levels.

PURPOSE: To describe how we performed a protocol review, analyzed data, identified opportunities to reduce radiation exposure, and then implemented a new imaging protocol for non-contrast adult head CT at our institution with reduced radiation exposure, using the Japanese diagnostic reference levels (DRLs) as the reference. METHODS: After analyzing the CT dose index (CTDIvol) and dose length product (DLP) in all non-contrast adult head CT examinations performed during a 3-month period (September to November 2015) in order to identify a specific protocol that contributed to the above-DRL-level radiation exposure observed for non-contrast adult head CT at our institution, phantom studies with objective and subjective image quality analyses were performed to develop a new imaging protocol. After implementing the new protocol, its feasibility was evaluated in terms of radiation exposure, prevalence of significant disease detection, and subjective image quality. RESULTS: The review of 2040 examinations revealed that a helical protocol (CTDIvol = 93.4 mGy) with one of four CT scanners mainly contributed to the above-DRL-level radiation exposure (mean DLP at this scanner = 1401.2 mGy cm) in non-contrast adult head CT at our institution. To replace this protocol, the phantom study identified a wide-volume scan using 120 kVp, 350 mAs, a 4-cm detector, a slice thickness of 5 mm, and a CTDIvol of 69.8 mGy as a new protocol that yielded comparable image quality to the existing protocol. After the implementation of the new protocol, the overall mean DLP reduced to 1365 mGy cm without any apparent degradation of image quality. No significant decrease in the prevalence of significant findings after protocol revision was noted. CONCLUSION: We report the successful implementation of a new protocol with reduced radiation exposure for non-contrast head CT examinations.

Frequency and Severity of Pulmonary Hemorrhage in Patients Undergoing Percutaneous CT-guided Transthoracic Lung Biopsy: Single-Institution Experience of 1175 Cases.

PURPOSE: To evaluate the frequency and severity of pulmonary hemorrhage after transthoracic needle lung biopsy (TTLB) and assess possible factors associated with pulmonary hemorrhage. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board. The requirement to obtain informed consent was waived. Records from 1113 patients who underwent 1175 TTLBs between January 2008 and April 2013 were retrospectively reviewed. Primary outcomes were pulmonary hemorrhage, documented hemoptysis, and bleeding complications necessitating intervention. Pulmonary hemorrhage was graded as follows: 0, none; 1, less than or equal to 2 cm around the needle; 2, more than 2 cm and sublobar; 3, at least lobar; and 4, hemothorax. Patient, technique, and lesion-related variables were evaluated as predictors of pulmonary hemorrhage. Patient-related variables included main pulmonary artery diameter (mPAD) at computed tomography (CT), pulmonary artery pressures at echocardiography and right-sided heart catheterization, medications, chronic lung disease, bleeding diathesis, and immunodeficiency. Technique- and lesion-related variables included needle gauge, number of passes, pleura-needle angle, lesion size and morphologic characteristics, and distance to pleura. Univariate analysis was performed with χ(2), Fisher exact, and Student t tests. RESULTS: Pulmonary hemorrhage occurred in 483 of the 1175 TTLBs (41.1%); hemoptysis was documented in 21 of the 1175 TTLBs (1.8%). Higher-grade hemorrhage (grade 2 or higher) occurred in 201 of the 1175 TTLBs (17.1%); five of the 1175 TTLBs (0.4%) necessitated hemorrhage-related admission. Higher-grade hemorrhage was more likely to occur with female sex (P = .001), older age (P = .003), emphysema (P = .004), coaxial technique (P = .025), nonsubpleural location (P < .001), lesion size of 3 cm or smaller (P < .001), and subsolid lesions (P = .028). Enlarged mPAD at CT (≥2.95 cm) was not significantly associated with higher-grade hemorrhage (P = .430). CONCLUSION: Pulmonary hemorrhage after TTLB is common but rarely requires intervention. An enlarged mPAD at CT may not be a risk factor for higher-grade hemorrhage.

Coronary artery calcium score and CT angiography in asymptomatic elderly patients with high pretest probability for coronary artery disease.

PURPOSE: To evaluate the role of coronary artery calcium scoring (CACS) and/or coronary CT angiography (CCTA) in asymptomatic elderly patients with high pretest probability for coronary artery disease (CAD). MATERIALS AND METHODS: Forty-eight consecutive asymptomatic elderly (>65 years) subjects who had a high pretest probability and underwent CACS/CCTA were included. Each CCTA was evaluated for adequacy for assessment of coronary stenosis. Significant stenosis (>50% diameter narrowing) was assessed on evaluable CT images and by invasive catheter angiography (ICA). RESULTS: All subjects were men with mean CACS of 880 ± 1779. Among those with low (0-99), intermediate (100-399), and high (400-999) CACS, ICA-verified significant stenosis was present in 8% (1/13), 23% (2/13), and 67% (8/12), respectively. Among those with very high CACS (≥ 1000) (n = 10), 90% of CCTAs were not evaluable for stenosis. CONCLUSION: In asymptomatic elderly subjects with high pretest probability, CACS followed by CCTA may be considered for those with intermediate to high CACS.

Medical 3D Printing for the Radiologist.

While use of advanced visualization in radiology is instrumental in diagnosis and communication with referring clinicians, there is an unmet need to render Digital Imaging and Communications in Medicine (DICOM) images as three-dimensional (3D) printed models capable of providing both tactile feedback and tangible depth information about anatomic and pathologic states. Three-dimensional printed models, already entrenched in the nonmedical sciences, are rapidly being embraced in medicine as well as in the lay community. Incorporating 3D printing from images generated and interpreted by radiologists presents particular challenges, including training, materials and equipment, and guidelines. The overall costs of a 3D printing laboratory must be balanced by the clinical benefits. It is expected that the number of 3D-printed models generated from DICOM images for planning interventions and fabricating implants will grow exponentially. Radiologists should at a minimum be familiar with 3D printing as it relates to their field, including types of 3D printing technologies and materials used to create 3D-printed anatomic models, published applications of models to date, and clinical benefits in radiology. Online supplemental material is available for this article.

The residual STL volume as a metric to evaluate accuracy and reproducibility of anatomic models for 3D printing: application in the validation of 3D-printable models of maxillofacial bone from reduced radiation dose CT images.

BACKGROUND: The effects of reduced radiation dose CT for the generation of maxillofacial bone STL models for 3D printing is currently unknown. Images of two full-face transplantation patients scanned with non-contrast 320-detector row CT were reconstructed at fractions of the acquisition radiation dose using noise simulation software and both filtered back-projection (FBP) and Adaptive Iterative Dose Reduction 3D (AIDR3D). The maxillofacial bone STL model segmented with thresholding from AIDR3D images at 100 % dose was considered the reference. For all other dose/reconstruction method combinations, a "residual STL volume" was calculated as the topologic subtraction of the STL model derived from that dataset from the reference and correlated to radiation dose. RESULTS: The residual volume decreased with increasing radiation dose and was lower for AIDR3D compared to FBP reconstructions at all doses. As a fraction of the reference STL volume, the residual volume decreased from 2.9 % (20 % dose) to 1.4 % (50 % dose) in patient 1, and from 4.1 % to 1.9 %, respectively in patient 2 for AIDR3D reconstructions. For FBP reconstructions it decreased from 3.3 % (20 % dose) to 1.0 % (100 % dose) in patient 1, and from 5.5 % to 1.6 %, respectively in patient 2. Its morphology resembled a thin shell on the osseous surface with average thickness <0.1 mm. CONCLUSION: The residual volume, a topological difference metric of STL models of tissue depicted in DICOM images supports that reduction of CT dose by up to 80 % of the clinical acquisition in conjunction with iterative reconstruction yields maxillofacial bone models accurate for 3D printing.

Comprehensive assessment of radiation dose estimates for the CORE320 study.

OBJECTIVE. The purpose of this study was to comprehensively study estimated radiation doses for subjects included in the main analysis of the Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography (CORE320) study ( ClinicalTrials.gov identifier NCT00934037), a clinical trial comparing combined CT angiography (CTA) and perfusion CT with the reference standard catheter angiography plus myocardial perfusion SPECT. SUBJECTS AND METHODS. Prospectively acquired data on 381 CORE320 subjects were analyzed in four groups of testing related to radiation exposure. Radiation dose estimates were compared between modalities for combined CTA and perfusion CT with respect to covariates known to influence radiation exposure and for the main clinical outcomes defined by the trial. The final analysis assessed variations in radiation dose with respect to several factors inherent to the trial. RESULTS. The mean radiation dose estimate for the combined CTA and perfusion CT protocol (8.63 mSv) was significantly (p < 0.0001 for both) less than the average dose delivered from SPECT (10.48 mSv) and the average dose from diagnostic catheter angiography (11.63 mSv). There was no significant difference in estimated CTA-perfusion CT radiation dose for subjects who had false-positive or false-negative results in the CORE320 main analyses in a comparison with subjects for whom the CTA-perfusion CT findings were in accordance with the reference standard SPECT plus catheter angiographic findings. CONCLUSION. Radiation dose estimates from CORE320 support clinical implementation of a combined CT protocol for assessing coronary anatomy and myocardial perfusion.

Incidental findings detection using low tube potential for CT pulmonary angiography.

While lowering the radiation dose using a reduced tube potential (kVp) strategy for CT pulmonary angiography (CTPA) maintains accuracy for pulmonary embolism detection, there is no data regarding the effect of increased noise from lower kVp on both the accuracy of lung and mediastinum lesion detection in the same patient cohort. This study compares the accuracy and diagnostic confidence of lung nodules and enlarged mediastinal lymph nodes detection between low and standard kVp CTPA. The study cohort included 272 CTPA studies acquired at low kVp and 274 studies at standard kVp. Each patient had a routine chest CT acquired within 60 days of the CTPA that served as a reference standard for lung and mediastinum lesions. In additional to the evaluation of image quality, two radiologists independently interpreted lung nodules and mediastinal lymph nodes on CTPA and recorded confidence level for each interpretation. Multivariate models assessed effect of kVp settings on diagnostic accuracy and confidence level in interpretation. Low kVp CTPAs had higher image noise. A significant decrease in the confidence levels for evaluation of mediastinal lymph nodes was observed at low kVp by one of two readers, although there was no significant correlation between accuracy of interpretation and kVp settings for lung and mediastinum lesion detection (adjusted odds ratios = 0.67-1.22, p values >0.2). While increased image noise may decrease the diagnostic confidence of the radiologist, the detection of lung nodules and enlarged mediastinal lymph nodes was not compromised. Referring clinicians can expect that lower radiation dose CTPA answers questions related to lungs and mediastinum.

Computed tomography and echocardiography in patients with acute pulmonary embolism: part 2: prognostic value.

PURPOSE: The aim of the study was to compare the prognostic value of right ventricular (RV) dysfunction detected on computed tomography pulmonary angiography (CTPA) and transthoracic echocardiography (TTE) in patients with acute pulmonary embolism (PE). MATERIALS AND METHODS: From all consecutive CTPAs performed between August 2003 and May 2010 that were positive for acute PE (n=1744), those with TTE performed within 48 hours of CTPA (n=785) were selected as the study cohort. Multivariate logistic regression analysis was performed to assess the association of CTPA RV/left ventricular (LV) diameter ratio and TTE RV strain with PE-related 30-day mortality, including other associated factors as covariates. The predictive ability (area under the curve) was compared between the model including the CT RV/LV diameter ratio and that including TTE RV strain. Test characteristics of the 2 modalities were calculated. RESULTS: Both CT RV/LV diameter ratio and TTE RV strain were independently associated with PE-related 30-day mortality (adjusted odds ratio=1.14, P=0.023 for 0.1 increment of the CT RV/LV diameter ratio; and odds ratio=2.13, P=0.041 for TTE RV strain). History of congestive heart failure and malignancy were independent predictors of PE-related mortality, while there was significantly lower mortality associated with anticoagulation use. The model including TTE RV strain and that including CT RV/LV had similar predictive ability (area under the curve=0.80 vs. 0.81, P=0.50). The sensitivity, specificity, and positive and negative predictive values of TTE RV strain and CT RV/LV diameter ratio at a cutoff of ≥1.0 were similar for PE-related 30-day mortality. CONCLUSIONS: Both RV strain on TTE and an increased CT RV/LV diameter ratio are predictors of PE-related 30-day mortality with similar prognostic significance.

Static and cine CT imaging to identify and characterize mediastinal adhesions as a potential complication for patients underdoing "redo sternotomy".

OBJECTIVE: The purpose of this article is to describe the image acquisition, identification, and reporting of postoperative adhesions in patients undergoing CT for "redo sternotomy" surgical planning. CONCLUSION: Adhesions appear as linear fibrous bands that join structures in the mediastinum viewed on static images. Confirmation by cine imaging shows deformation of mediastinal structures. Identification and reporting of adhesions will likely guide surgeons to safer interventions.