Hip Imaging in Children With Cerebral Palsy: Estimation and Intrapatient Comparison of Patient-Specific Radiation Doses of Low-Dose CT and Radiography.

OBJECTIVES: Hip displacement is the second most common orthopedic problem affecting children with cerebral palsy (CP). Routine radiographic hip surveillance typically involves an anteroposterior (AP) pelvis radiograph. Unfortunately, this imaging protocol is limited by its projectional technique and the positioning challenges in children with CP. Alternatively, hip low-dose computed tomography (LDCT) has been advocated as a more accurate strategy for imaging surveillance as it provides biofidelic details of the hip that is independent of patient positioning. However, the tradeoff is the (presumed) higher radiation dose to the patient. The goal of this study is to estimate patient-specific radiation doses of hip LDCTs and AP pelvis radiographs in CP patients, and perform an intrapatient dose comparison. MATERIALS AND METHODS: A search of our imaging database was performed to identify children with CP who underwent hip LDCT and AP pelvis radiograph within 6 months of each other. The LDCTs were performed using weight-adjusted kVp and tube current modulation, whereas the radiographs were obtained with age-/size-adjusted kVp/mAs. The patient-specific organ and effective doses for LDCT were estimated by matching the patients to a nonreference pediatric phantom library from the National Cancer Institute Dosimetry System for Computed Tomography database with Monte Carlo-based dosimetry. The patient-specific organ and effective doses for radiograph were estimated using the National Cancer Institute Dosimetry System for Radiography and Fluoroscopy with Monte Carlo-based dose calculation. Dose conversion k-factors of dose area product for radiography and dose length product for LDCT were adapted, and the estimation results were compared with patient-specific dosimetry. RESULTS: Our study cohort consisted of 70 paired imaging studies from 67 children (age, 9.1 ± 3.3 years). The patient-specific and dose length product-based effective doses for LDCT were 0.42 ± 0.21 mSv and 0.59 ± 0.28 mSv, respectively. The patient-specific and dose area product-based effective doses for radiography were 0.14 ± 0.09 mSv and 0.08 ± 0.06 mSv, respectively. CONCLUSIONS: The radiation dose for a hip LDCT is ~4 times higher than pelvis radiograph, but it is still very low and poses minimal risk to the patient.

Radiographic assessment of traction-induced esophageal growth and traction-related complications of the Foker process for treatment of long-gap esophageal atresia.

BACKGROUND: Radiographic assessment of esophageal growth in long-gap esophageal atresia while on traction and associated traction-related complications have not been described. OBJECTIVE: To demonstrate how chest radiography can estimate esophageal position while on traction and to evaluate radiography's utility in diagnosing certain traction system complications. MATERIALS AND METHODS: In this retrospective evaluation of portable chest radiographs obtained in infants with long-gap esophageal atresia who underwent the Foker process between 2014 and 2020, we assessed distances between the opposing trailing clips (esophageal gap) and the leading and trailing clips for each esophageal segment on serial radiographs. Growth during traction was estimated using longitudinal random-effects regression analysis to account for multiple chest radiograph measurements from the same child. RESULTS: Forty-three infants (25 male) had a median esophageal gap of 4.5 cm. Median traction time was 14 days. Median daily radiographic esophageal growth rate for both segments was 2.2 mm and median cumulative growth was 23.6 mm. Traction-related complications occurred in 13 (30%) children with median time of 8 days from traction initiation. Daily change >12% in leading-to trailing clip distance demonstrated 86% sensitivity and 92% specificity for indicating traction-related complications (area under the curve [AUC] 0.853). Cumulative change >30% in leading- to trailing-clip distance during traction was 85% sensitive and 85% specific for indicating traction complications (AUC 0.874). CONCLUSION: Portable chest radiograph measurements can serve as a quantitative surrogate for esophageal segment position in long-gap esophageal atresia. An increase of >12% between two sequential chest radiographs or >30% increase over the traction period in leading- to trailing-clip distance is highly associated with traction system complications.

Leveraging the Combined Predictive Value of Ultrasound and Laboratory Data to Reduce Radiation Exposure and Resource Utilization in Children with Suspected Appendicitis.

BACKGROUND: Previous investigation has shown that the combined predictive value of white blood cell count and ultrasound (US) findings to be superior to either alone in children with suspected appendicitis. The purpose of this study was to evaluate the impact of a diagnostic clinical pathway (DCP) leveraging the combined predictive value of these tests on computed tomography (CT) utilization and resource utilization. METHODS: Retrospective cohort study comparing 8 mo of data before DCP implementation to 18 mo of data following implementation. The pathway incorporated decision-support for disposition (operative intervention, observation, or further cross-sectional imaging) based on the combined predictive value of laboratory and US data (stratifying patients into low, moderate, and high-risk groups). Study measures included CT and magnetic resonance imaging utilization, imaging-related cost, time to appendectomy, and negative appendectomy rate. RESULTS: Ninety-seven patients in the preintervention period were compared with 319 patients in the postintervention period. Following DCP implementation, CT utilization decreased by 86% (21% versus 3%, P < 0.001). Mean time to appendectomy decreased from 8.5 to 7.2 h (P < 0.001), and the negative appendectomy rate remained unchanged (5% versus 4%, P = 0.54). Magnetic resonance imaging utilization increased following pathway implementation (1% versus 7%, P = 0.02); however, median imaging-related cost was significantly lower in the postimplementation period ($283/case to $270/case, P = 0.002) CONCLUSIONS: In children with suspected appendicitis, implementation of a DCP leveraging the combined predictive value of white blood cell and US data was associated with a reduction in CT utilization, time to appendectomy, and imaging-related cost.

Curved planar reformatting and convolutional neural network-based segmentation of the small bowel for visualization and quantitative assessment of pediatric Crohn's disease from MRI.

BACKGROUND: Contrast-enhanced MRI of the small bowel is an effective imaging sequence for the detection and characterization of disease burden in pediatric Crohn's disease (CD). However, visualization and quantification of disease burden requires scrolling back and forth through 3D images to follow the anatomy of the bowel, and it can be difficult to fully appreciate the extent of disease. PURPOSE: To develop and evaluate a method that offers better visualization and quantitative assessment of CD from MRI. STUDY TYPE: Retrospective. POPULATION: Twenty-three pediatric patients with CD. FIELD STRENGTH/SEQUENCE: 1.5T MRI system and T1 -weighted postcontrast VIBE sequence. ASSESSMENT: The convolutional neural network (CNN) segmentation of the bowel's lumen, wall, and background was compared with manual boundary delineation. We assessed the reproducibility and the capability of the extracted markers to differentiate between different levels of disease defined after a consensus review by two experienced radiologists. STATISTICAL TESTS: The segmentation algorithm was assessed using the Dice similarity coefficient (DSC) and boundary distances between the CNN and manual boundary delineations. The capability of the extracted markers to differentiate between different disease levels was determined using a t-test. The reproducibility of the extracted markers was assessed using the mean relative difference (MRD), Pearson correlation, and Bland-Altman analysis. RESULTS: Our CNN exhibited DSCs of 75 ± 18%, 81 ± 8%, and 97 ± 2% for the lumen, wall, and background, respectively. The extracted markers of wall thickness at the location of min radius (P = 0.0013) and the median value of relative contrast enhancement (P = 0.0033) could differentiate active and nonactive disease segments. Other extracted markers could differentiate between segments with strictures and segments without strictures (P < 0.05). The observers' agreement in measuring stricture length was >3 times superior when computed on curved planar reformatting images compared with the conventional scheme. DATA CONCLUSION: The results of this study show that the newly developed method is efficient for visualization and assessment of CD. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1565-1576.

Development of a Standardized Kalamazoo Communication Skills Assessment Tool for Radiologists: Validation, Multisource Reliability, and Lessons Learned.

OBJECTIVE: The purpose of this study was to develop and test a standardized communication skills assessment instrument for radiology. MATERIALS AND METHODS: The Delphi method was used to validate the Kalamazoo Communication Skills Assessment instrument for radiology by revising and achieving consensus on the 43 items of the preexisting instrument among an interdisciplinary team of experts consisting of five radiologists and four nonradiologists (two men, seven women). Reviewers assessed the applicability of the instrument to evaluation of conversations between radiology trainees and trained actors portraying concerned parents in enactments about bad news, radiation risks, and diagnostic errors that were video recorded during a communication workshop. Interrater reliability was assessed by use of the revised instrument to rate a series of enactments between trainees and actors video recorded in a hospital-based simulator center. Eight raters evaluated each of seven different video-recorded interactions between physicians and parent-actors. RESULTS: The final instrument contained 43 items. After three review rounds, 42 of 43 (98%) items had an average rating of relevant or very relevant for bad news conversations. All items were rated as relevant or very relevant for conversations about error disclosure and radiation risk. Reliability and rater agreement measures were moderate. The intraclass correlation coefficient range was 0.07-0.58; mean, 0.30; SD, 0.13; and median, 0.30. The range of weighted kappa values was 0.03-0.47; mean, 0.23; SD, 0.12; and median, 0.22. Ratings varied significantly among conversations (χ26 = 1186; p < 0.0001) and varied significantly by viewing order, rater type, and rater sex. CONCLUSION: The adapted communication skills assessment instrument is highly relevant for radiology, having moderate interrater reliability. These findings have important implications for assessing the relational competencies of radiology trainees.

Spatially-constrained probability distribution model of incoherent motion (SPIM) for abdominal diffusion-weighted MRI.

Quantitative diffusion-weighted MR imaging (DW-MRI) of the body enables characterization of the tissue microenvironment by measuring variations in the mobility of water molecules. The diffusion signal decay model parameters are increasingly used to evaluate various diseases of abdominal organs such as the liver and spleen. However, previous signal decay models (i.e., mono-exponential, bi-exponential intra-voxel incoherent motion (IVIM) and stretched exponential models) only provide insight into the average of the distribution of the signal decay rather than explicitly describe the entire range of diffusion scales. In this work, we propose a probability distribution model of incoherent motion that uses a mixture of Gamma distributions to fully characterize the multi-scale nature of diffusion within a voxel. Further, we improve the robustness of the distribution parameter estimates by integrating spatial homogeneity prior into the probability distribution model of incoherent motion (SPIM) and by using the fusion bootstrap solver (FBM) to estimate the model parameters. We evaluated the improvement in quantitative DW-MRI analysis achieved with the SPIM model in terms of accuracy, precision and reproducibility of parameter estimation in both simulated data and in 68 abdominal in-vivo DW-MRIs. Our results show that the SPIM model not only substantially reduced parameter estimation errors by up to 26%; it also significantly improved the robustness of the parameter estimates (paired Student's t-test, p < 0.0001) by reducing the coefficient of variation (CV) of estimated parameters compared to those produced by previous models. In addition, the SPIM model improves the parameter estimates reproducibility for both intra- (up to 47%) and inter-session (up to 30%) estimates compared to those generated by previous models. Thus, the SPIM model has the potential to improve accuracy, precision and robustness of quantitative abdominal DW-MRI analysis for clinical applications.

In vivo assessment of optimal b-value range for perfusion-insensitive apparent diffusion coefficient imaging.

PURPOSE: To assess the optimal b-values range for perfusion-insensitive apparent diffusion coefficient (ADC) imaging of abdominal organs using short-duration DW-MRI acquisitions with currently available ADC estimation methods. METHODS: DW-MRI data of 15 subjects were acquired with eight b-values in the range of 5-800 s∕mm(2). The reference-standard, a perfusion insensitive, ADC value (ADC(IVIM)), was computed using an intravoxel incoherent motion (IVIM) model with all acquired diffusion-weighted images. Simulated DW-MRI data was generated using an IVIM model with b-values in the range of 0-1200 s∕mm(2). Monoexponential ADC estimates were calculated using: (1) Two-point estimator (ADC(2)); (2) least squares three-point (ADC(3)) estimator and; (3) Rician noise model estimator (ADC(R)). The authors found the optimal b-values for perfusion-insensitive ADC calculations by minimizing the relative root mean square error (RRMS) between the ADC(IVIM) and the monoexponential ADC values for each estimation method and organ. RESULTS: Low b-value = 300 s∕mm(2) and high b-value = 1200 s∕mm(2) minimized the RRMS between the estimated ADC and the reference-standard ADC(IVIM) to less than 5% using the ADC(3) estimator. By considering only the in vivo DW-MRI data, the combination of low b-value = 270 s∕mm(2) and high b-value of 800 s∕mm(2) minimized the RRMS between the estimated ADC and the reference-standard ADC(IVIM) to <7% using the ADC(3) estimator. For all estimators, the RRMS between the estimated ADC and the reference standard ADC correlated strongly with the perfusion-fraction parameter of the IVIM model (r = [0.78-0.83], p ≤ 0.003). CONCLUSIONS: The perfusion compartment in DW-MRI signal decay correlates strongly with the RRMS in ADC estimates from short-duration DW-MRI. The impact of the perfusion compartment on ADC estimations depends, however, on the choice of b-values and estimation method utilized. Likewise, perfusion-related errors can be reduced to <7% by carefully selecting the b-values used for ADC calculations and method of estimation.

Image Gently(SM): a national education and communication campaign in radiology using the science of social marketing.

Communication campaigns are an accepted method for altering societal attitudes, increasing knowledge, and achieving social and behavioral change particularly within public health and the social sciences. The Image Gently(SM) campaign is a national education and awareness campaign in radiology designed to promote the need for and opportunities to decrease radiation to children when CT scans are indicated. In this article, the relatively new science of social marketing is reviewed and the theoretical basis for an effective communication campaign in radiology is discussed. Communication strategies are considered and the type of outcomes that should be measured are reviewed. This methodology has demonstrated that simple, straightforward safety messages on radiation protection targeted to medical professionals throughout the radiology community, utilizing multiple media, can affect awareness potentially leading to change in practice.

Harderian gland adenectomy: a method to eliminate confounding radio-opacity in the assessment of rat brain metabolism by 18F-fluoro-2-deoxy-D-glucose positron emission tomography.

The 18F isotope of fluoro-2-deoxy-D-glucose (FDG) is a radiotracer commonly used in positron emission tomography (PET) for determining regional metabolic activity in the brain. However, in rats and many other species with nictitating membranes, harderian glands located just behind the eyes aggressively incorporate 18F-FDG to the extent that PET images of the brain become obscured. This radioactive spillover, or 'partial volume error,' combined with the limited spatial resolution of microPET scanners (1.5 to 2 mm) may markedly reduce the ability to quantify neuronal activity in frontal brain structures. Theoretically, surgical removal of the harderian glands before 18F-FDG injection would eliminate the confounding uptake of the radioactive tracer and thereby permit visualization of glucose metabolism in the frontal brain. We conducted a pilot study of unilateral harderian gland adenectomy, leaving the contralateral gland intact for comparison. At 1 wk after surgery, each rat was injected intravenously with 18F-FDG, and 40 min later underwent brain microPET for 20 min. Review of the resulting images showed that the frontal cortex on the surgical side was defined more clearly, with only background 18F-FDG accumulation in the surgical bed. Activity in the frontal cortex on the intact side was obscured by intense accumulation of 18F-FDG in the harderian gland. By reducing partial volume error, this simple surgical procedure may become a valuable tool for visualization of the frontal cortex of rat brain by 18F-FDG microPET imaging.