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ObjectivesTo establish the level of observer variation for the current ATS/ERS/JRS/ALAT criteria for a diagnosis of usual interstitial pneumonia (UIP) on CT among a large group of thoracic radiologists of varying levels of experience.Materials and methods112 observers (96 of whom were thoracic radiologists) categorised CTs of 150 consecutive patients with fibrotic lung disease using the ATS/ERS/JRS/ALAT CT criteria for a UIP pattern (3 categories—UIP, possibly UIP and inconsistent with UIP). The presence of honeycombing, traction bronchiectasis and emphysema was also scored using a 3-point scale (definitely present, possibly present, absent). Observer agreement for the UIP categorisation and for the 3 CT patterns in the entire observer group and in subgroups stratified by observer experience, were evaluated.ResultsInterobserver agreement across the diagnosis category scores among the 112 observers was moderate, ranging from 0.48 (IQR 0.18) for general radiologists to 0.52 (IQR 0.20) for thoracic radiologists of 10–20 years’ experience. A binary score for UIP versus possible or inconsistent with UIP was examined. Observer agreement for this binary score was only moderate. No significant differences in agreement levels were identified when the CTs were stratified according to multidisciplinary team (MDT) diagnosis or patient age or when observers were categorised according to experience. Observer agreement for each of honeycombing, traction bronchiectasis and emphysema were 0.59±0.12, 0.42±0.15 and 0.43±0.18, respectively.ConclusionsInterobserver agreement for the current ATS/ERS/JRS/ALAT CT criteria for UIP is only moderate among thoracic radiologists, irrespective of their experience, and did not vary with patient age or the MDT diagnosis.

ObjectivesThe aim of this study was to compare image quality of single-source dual-energy CT (SS-DECT) with third-generation dual-source dual-energy CT (DS-DECT) in head and neck cancer.Materials and methodsOne hundred two patients with histologically proven head and neck cancer were prospectively randomized to undergo radiation dose-matched SS-DECT (n = 51, 120 kV, split-filter technique, 384 ref. mAs) or DS-DECT (n = 51, 80/Sn150 kV, tube A 100/tube B 67 ref. mAs). Inline default images (DI) and virtual monoenergetic images (VMI) for two different low energies (40 and 60 keV) were reconstructed. Objective image quality was evaluated as dose-normalized contrast to noise ratio (CNRD), and subjective image quality was rated on a 5-point Likert scale.ResultsIn both groups, highest CNRD values for vessel and tumor attenuation were obtained at 40 keV. DS-DECT was significantly better than SS-DECT regarding vessel and tumor attenuation. Overall subjective image quality in the SS-DECT group was highest on the DI followed by 40 keV and 60 keV. In the DS-DECT group, subjective image quality was highest at 40 keV followed by 60 keV and the DI. Forty kiloelectron volts and 60 keV were significantly better in the DS-DECT compared to the SS-DECT group (both p < 0.01).ConclusionsIn split-filter SS-DECT as well as in DS-DECT, highest overall image quality in head and neck imaging can be obtained with a combination of DI and low keV reconstructions. DS-DECT is superior to split-filter SS-DECT in terms of subjective image quality and vessel and tumor attenuation.Key Points• Image quality was diagnostic with both dual-energy techniques; however, the dual-source technique delivered significantly better results.• Highest overall image quality in head and neck imaging can be obtained with a combination of default images and low keV reconstructions with both dual-energy techniques.• The results of this study may have relevance for the decision-making process regarding replacement of CT scanners and focused patient examination considering image quality and subsequent therapeutic decision-making.

Background Conventional radiostereometric analysis (RSA) has been used for several decades to assess implant migration in total knee arthroplasty (TKA). More recently, computed tomography–based radiostereometric analysis (CT-RSA) has been introduced as an alternative. Experimental studies have demonstrated acceptable precision for CT-RSA; however, this has not yet been validated in a clinical setting. With the emergence of new alignment philosophies in TKA, migration analysis of femoral components has become increasingly important. A key criticism of CT-RSA has been the higher radiation doses compared with conventional RSA, particularly in longitudinal studies involving repeated CT scans. In this study, we evaluated the precision of CT-RSA for assessing femoral component migration in two TKA designs at two different radiation dose levels. We hypothesized that there would be no clinically relevant difference in precision between the two radiation dose levels. Methods We performed a randomized controlled trial of 50 patients using Tritanium and GMK Sphere 3D Metal implants and analysed the precision of the method through double examinations expressed as means with 95% confidence intervals at standard and low-dose levels. The main outcome variable was the difference in mean maximum total point motion. We set the clinical meaningful difference to be more than 0.1 mm based on existing literature. Secondary outcome variables were the means and standard deviations of the translation and rotation of the implants. Findings We found a precision of (mean, standard deviation) 0.20 (0.08) and 0.17 mm (0.06) for standard and low dose respectively, giving a difference (95% confidence interval) of − 0.03 mm (− 0.06–0.00). P -value was 0.031. Variability ratios were 0.009 for the standard deviation test. Interpretation In this first clinical study to assess the precision of computed tomography–based radiostereometric analysis for femoral implants in total knee arthroplasty, we found no clinically relevant difference in precision. Our findings confirm that CT-RSA provides sufficient precision in a clinical setting to enable migration analysis of femoral implants in total knee arthroplasty, even when using very low radiation doses. Highlights CT-RSA can be used to analyse migration of femoral implants in total knee arthroplasty.

Objective To evaluate and improve the interobserver agreement for the CT-based diagnosis of diffuse idiopathic skeletal hyperostosis (DISH). Methods Six hundred participants of the CT arm of a lung cancer screening trial were randomly divided into two groups. The first 300 CTs were scored by five observers for the presence of DISH based on the original Resnick criteria for radiographs. After analysis of the data a consensus meeting was organised and the criteria were slightly modified regarding the definition of ‘contiguous’, the definition of ‘flowing ossifications’ and the viewing plane and window level. Subsequently, the second set of 300 CTs was scored by the same observers. κ ≥ 0.61 was considered good agreement. Results The 600 male participants were on average 63.5 (SD 5.3) years old and had smoked on average 38.0 pack-years. In the first round κ values ranged from 0.32 to 0.74 and 7 out of 10 values were below 0.61. After the consensus meeting the interobserver agreement ranged from 0.51 to 0.86 and 3 out of 10 values were below 0.61. The agreement improved significantly. Conclusions This is the first study that reports interobserver agreement for the diagnosis of DISH on chest CT, showing mostly good agreement for modified Resnick criteria. Key Points • DISH is diagnosed on fluoroscopic and radiographic examinations using Resnick criteria • Evaluation of DISH on chest CT was modestly reproducible with the Resnick criteria • A consensus meeting and Resnick criteria modification improved inter-rater reliability for DISH • Reproducible CT criteria for DISH aids research into this poorly understood entity

Purpose The purpose of this study was to assess the parameters and performance of CT protocols collected in numerous annual medical physics CT equipment performance evaluations (EPEs), develop clinically relevant performance targets for select phantom tests, and provide guidance for medical physicists about appropriate CT imaging parameters. Background The results of CT scanner annual physics testing depend on the clinical protocols used at the facility, with a key image quality parameter dependent on the associated radiation dose. The American College of Radiology (ACR) accreditation process and quality control manual impose criteria on these parameters, but these minimum criteria are not meaningful performance targets for clinically acceptable protocols. Methods A mathematical relationship between dose and contrast‐to‐noise ratio (CNR) was developed to evaluate test results and guide protocol adjustments. Historical testing results, including CNR and measured CTDIvol were collected from 111 completed annual EPEs, and the results were compared to ACR criteria and published guidance on scanning parameters. Results The average and 75th percentile CDTIvol values were markedly lower than the ACR reference values, while the average and 25th percentile CNR values were markedly higher than the ACR minimum reference values. Scanners where iterative reconstruction (IR) was used did not show lower CTDIvol values than scanners using filtered backprojection. Protocol parameters in routine clinical use showed high rates of deviation from published reference protocols and clinical imaging guidelines. Conclusions Modern CT scanners likely can exceed ACR accreditation targets for image quality at radiation dose levels well below the ACR limits. Clinical medical physicists can use the approach described in this study to recommend clinical protocol improvements when performing physics testing. Medical physicists can engage with radiologists and technologists to determine whether published protocol guidelines are appropriate for clinical needs and can use the simple mathematical relationship described in this paper to translate protocols for modifications such as reduced slice thickness.

The Pediatric Emergency Care Applied Research Network prediction rules for minor head trauma identify children at very low, intermediate, and high risk of clinically important traumatic brain injuries (ciTBIs) and recommend no computed tomography (CT) for those at very low risk. However, the prediction rules provide little guidance in the choice of home observation or CT in children at intermediate risk for ciTBI. To compare a decision aid with usual care in parents of children at intermediate risk for ciTBI. This cluster randomized trial was conducted in 7 geographically diverse US emergency departments (EDs) from April 1, 2014, to September 30, 2016. Eligible participants were emergency clinicians, children ages 2 to 18 years with minor head trauma at intermediate risk for ciTBI, and their parents. Clinicians were randomly assigned (1:1 ratio) to shared decision-making facilitated by the Head CT Choice decision aid or to usual care. The primary outcome, selected by parent stakeholders, was knowledge of their child's risk for ciTBI and the available diagnostic options. Secondary outcomes included decisional conflict, parental involvement in decision-making, the ED CT rate, 7-day health care utilization, and missed ciTBI. A total of 172 clinicians caring for 971 children (493 decision aid; 478 usual care) with minor head trauma at intermediate risk for ciTBI were enrolled. The patient mean (SD) age was 6.7 (7.1) years, 575 (59%) were male, and 253 (26%) were of nonwhite race. Parents in the decision aid arm compared with the usual care arm had greater knowledge (mean [SD] questions correct: 6.2 [2.0] vs 5.3 [2.0]; mean difference, 0.9; 95% CI, 0.6-1.3), had less decisional conflict (mean [SD] decisional conflict score, 14.8 [15.5] vs 19.2 [16.6]; mean difference, -4.4; 95% CI, -7.3 to -2.4), and were more involved in CT decision-making (observing patient involvement [OPTION] scores: mean [SD], 25.0 [8.5] vs 13.3 [6.5]; mean difference, 11.7; 95% CI, 9.6-13.9). Although the ED CT rate did not significantly differ (decision aid, 22% vs usual care, 24%; odds ratio, 0.81; 95% CI, 0.51-1.27), the mean number of imaging tests was lower in the decision aid arm 7 days after injury. No child had a missed ciTBI. Use of a decision aid in parents of children at intermediate risk of ciTBI increased parent knowledge, decreased decisional conflict, and increased involvement in decision-making. The intervention did not significantly reduce the ED CT rate but safely decreased health care utilization 7 days after injury. ClinicalTrials.gov Identifier: NCT02063087.

PurposeIncreasingly, radiologic imaging is obtained as part of the pathway in diagnosing ventral hernias. Often, radiologists receive incomplete or incorrect clinical information from clinicians. Objective: The aim of the study is to determine if clinical exam findings alter radiological interpretation of ventral hernias on CT.MethodsThis is a single-institution double-blind, randomized trial. All patients with a recent abdominal/pelvic CT scan seen in various surgical clinics were enrolled. A surgeon blinded to the CT scan findings performed a standardized physical examination and assessed for the presence of a ventral hernia. Seven independent radiologists blinded to the study design reviewed the scans. Each radiologist received one of three types of clinical exam data per CT: accurate (correct), inaccurate (purposely incorrect), or none. Allocation was random and stratified by the presence of clinical hernia. The primary outcome was the proportion of radiologic hernias detected, analyzed by chi square.Results115 patients were enrolled for a total of 805 CT scan reads. The proportion of hernias detected differed by up to 25% depending on if accurate, no, or inaccurate clinical information was provided. Inaccurate clinical data in patients with no hernia on physical exam led to a significant difference in the radiologic hernia detection rate (54.3% versus 35.7%, p = 0.007). No clinical data in patients with a hernia on physical exam led to a lower radiologic hernia detection rate (75.0% versus 93.8%, p = 0.001).ConclusionsThe presence and accuracy of clinical information provided to radiologists impacts the diagnosis of abdominal wall hernias in up to 25% of cases. Standardization of both clinical and radiologic examinations for hernias and their reporting are needed.Trial registrationClinicaltrials.gov, Number NCT03121131, https://clinicaltrials.gov/ct2/show/NCT03121131.

Objective To investigate the feasibility of standardizing RT simulation CT scanner protocols between vendors using target‐based image quality (IQ) metrics. Method and materials A systematic assessment process in phantom was developed to standardize clinical scan protocols for scanners from different vendors following these steps: (a) images were acquired by varying CTDIvol and using an iterative reconstruction (IR) method (IR: iDose and model‐based iterative reconstruction [IMR] of CTp‐Philips Big Bore scanner, SAFIRE of CTs‐Siemens biograph PETCT scanner), (b) CT exams were classified into body and brain protocols, (c) the rescaled noise power spectrum (NPS) was calculated, (d) quantified the IQ change due to varied CTDIvol and IR, and (e) matched the IR strength level. IQ metrics included noise and texture from NPS, contrast, and contrast‐to‐noise ratio (CNR), low contrast detectability (d′). Area under curve (AUC) of the receiver operation characteristic curve of d′ was calculated and compared. Results The level of change in the IQ ratio was significant (>0.6) when using IMR. The IQ ratio change was relatively low to moderate when using either iDose in CTp (0.1–0.5) or SAFIRE in CTs (0.1–0.6). SAFIRE‐2 in CTs showed a closer match to the reference body protocol when compared to iDose‐3 in CTp. In the brain protocol, iDose‐3 in CTp could be matched to the low to moderate level of SAFIRE in CTs. The AUC of d′ was highest when using IMR in CTp with lower CTDIvol, and SAFIRE in CTs performed better than iDose in CTp Conclusion It is possible to use target‐based IQ metrics to evaluate the performance of the system and operations across various scanners in a phantom. This can serve as an initial reference to convert clinical scanned protocols from one CT simulation scanner to another.

•First randomized trial comparing thrombolytic treatment-delay for CT versus MRI-examined acute stroke patients.•The trial is based on a comprehensive number of consecutive patients and was conducted in a well-established stroke-unit.•MRI was not feasible in 48.9% of MRI-allocated.•CT-based thrombolysis in acute stroke patients is significantly faster compared with MRI-based assessment.•MR-based assessment of acute stroke patients prior to intravenous treatment is a potential option in the acute stroke setting. Door-Needle-times (DNT) of 20min are feasible when Computer Tomography (CT) is used for first-line brain-imaging to assess stroke-patients’ eligibility for intravenous-tissue-Plasminogen-Activator (iv-tPA), but the more time-consuming Magnetic Resonance Imaging (MRI)-based-evaluation is superior in detecting acute ischaemia.

To compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium. A total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80 kVp, 300 mgI/ml; group B: n=34, 100 kVp, 300 mgI/ml; group C: n=36, 120 kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests. The values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.51 ± 0.70 mSv) and group B (2.59 ± 1.24 mSv) were both lower than group C (4.92 ± 2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10 ± 0.41), group B (3.90 ± 0.48) and group C (4.04 ± 0.36) (each P > 0.05). Low tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction.