Savings in CT Net Scan Energy Consumption: Assessment Using Dose Report Metrics and Comparison With Savings in Idle State Energy Consumption.

BACKGROUND. CT scanners' net scan state (i.e., image acquisition period) represents a potential target for energy savings through protocol adjustments. However, gauging CT energy savings is difficult without installing costly energy monitors. OBJECTIVE. The purpose of this article was to assess correlations between CT dose report metrics and energy consumption during the system net scan state and to compare theoretic energy savings from matching percentage reductions in energy consumption during net scan and idle system states. METHODS. Current sensors were installed on a single CT scanner. A phantom was scanned at varying kilovoltage settings and effective tube current-rotation time settings. A retrospective assessment was performed in 32 patients (mean age, 61.2 ± 17.9 [SD] years; 17 men, 15 women) who underwent 32 single-energy noncontrast abdominopelvic CT examinations from September 22, 2021, to September 27, 2021, on the same scanner. Correlations between dose report metrics and net scan energy consumption were assessed in the phantom and clinical scans, and equations were generated to derive net scan energy consumption from DLP. An additional retrospective assessment was performed in 1355 patients (mean age, 59.3 ± 16.9 years; 663 men, 692 women) who underwent 1728 single-energy noncontrast abdominopelvic CT examinations from January 1, 2021, through December 31, 2021, on the same scanner to estimate net scan energy consumption per examination. This information was integrated with literature-derived values to compare estimated annual national energy savings resulting from 20% reductions in net scan and idle state energy consumption. RESULTS. Net scan energy consumption in the phantom scans showed high linear correlation with DLP (R2 = 0.87), and, in the clinical scans, high linear correlation with CTDIvol (R2 = 0.89) and very high linear correlation with DLP (R2 = 0.92). When combining mean DLP in examinations performed in the 1-year interval, an equation relating DLP and net scan energy consumption and literature values estimated that annual national energy savings was 14.9 times greater (40,437,870 kWh/2,704,000 kWh) by targeting the idle state rather than net scan state. CONCLUSION. CT net scan energy savings can be inferred from reductions in dose report metrics. However, targeting net scan energy consumption has modest impact relative to targeting idle state energy consumption. CLINICAL IMPACT. Environmental sustainability efforts should target the idle state energy consumption of CT.

Surgical Considerations in the Optimal Management of Patients with Malignant Brain Tumors.

OPINION STATEMENT: Advances in technology are revolutionizing medicine and the limits of what we can offer to our patients. In neurosurgery, technology continues to reduce morbidity, increase surgical accuracy, facilitate tissue acquisition, and promote novel techniques for prolonging survival in patients with neuro-oncologic disease. Surgery has been the backbone of glioma diagnosis and treatment by providing adequate, high quality material for precise histologic diagnosis, and genomic characterization in the setting of significant intratumoral heterogeneity, thus allowing personalized treatment selection in the clinic. The ability to obtain and accurately measure the maximal extent of resection in glioma surgery also remains a central role of the neurosurgeon in managing this cancer. To meet these goals, today's operating room has transformed from the traditional operating table and anesthesia machine to include neuronavigation instrumentation, intraoperative computed tomography, and magnetic resonance imaging scanners, advanced surgical microscopes fitted with fluorescent light filters, and electrocorticography machines. While surgeons, oncologists, and radiation oncologists all play unique critical roles in the care of patients with malignant gliomas, familiarity with developing techniques in complimentary subspecialties can enhance coordination of patient care, research productivity, professional interactions, and patient confidence and comfort with the physician team. Herein, we provide a summary of the advances in the field of neurosurgical oncology which allow more precise and optimal surgical resection for patients with malignant gliomas.

Longitudinal evaluation of neurobehavioral outcomes after carotid revascularization.

BACKGROUND: Carotid revascularization, including carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS), is performed for stroke risk reduction but may also impact cognitive function. Cognitive outcomes observed after carotid revascularization have been inconsistent, and mechanistic relationships with procedural factors are poorly understood. To further explore associations between carotid revascularization and cognitive outcomes, a prospective longitudinal evaluation was conducted of patients undergoing elective CEA or CAS for hemodynamically significant carotid stenosis. METHODS: Patients undergoing primary carotid artery revascularization for hemodynamically significant stenosis were evaluated with neurologic and neuropsychological testing at baseline and at 1 and 6 months after revascularization. A subgroup of patients was also studied with baseline and postoperative magnetic resonance imaging (MRI). Outcomes included neurologic or neuropsychological deficits and imaging findings (including quantitative assessment of cerebral blood flow). RESULTS: Sixteen patients underwent carotid revascularization with both preoperative and postoperative neurologic and neuropsychological testing; preoperative and postoperative MRIs were also performed on eight patients. Five of 16 treated carotid lesions (31%) were considered symptomatic, and severity of carotid stenosis was 60-79% for 6 of 16 lesions and 80% or more in all others. A single perioperative neurologic deficit was identified; all other patients (15/16) had no abnormalities detected by neurologic examination. Neuropsychological testing identified new postoperative deficits in 3 patients (19%), among whom 2 had a normal neurologic examination at all time points, whereas 1 had clinical evidence of stroke. Quantitative analysis of mean cerebral blood flow revealed postrevascularization increases for both gray matter (48.6 ± 13.9 mL per 100 g/min vs 75.3 ± 70.8 mL per 100 g/min) and white matter (31.8 ± 10.6 mL per 100 g/min vs 55.2 ± 30.1 mL per 100 g/min)(P = 0.04). New postoperative MRI foci of restricted diffusion were identified in 2 patients, both of whom had no neurologic or neuropsychological deficit. Among patients with postoperative neuropsychological deficits, MRI revealed globally increased cerebral perfusion without new postoperative abnormalities in 2 of 3. CONCLUSIONS: The relationship between carotid revascularization and cognitive function is complex, and cognitive deficits may occur in the presence of increased cerebral perfusion without detectable embolization.

Impact of the Radiology Scholars Certificate Program: Does It Persist Years After Program Completion?

RATIONALE AND OBJECTIVE: The Radiology Scholars Certificate Program (RSCP) is an elective course for preclinical medical students which aims to improve radiology knowledge, dispel misconceptions regarding the field, and train future clinicians who have a greater understanding of the scope of the field. Previously, we have shown that students demonstrate improved knowledge of radiological topics as well as improved perception of radiology as a field after completing the program. In this study we attempt to determine whether these effects persist up to two years following program completion. MATERIAL AND METHODS: A two-part questionnaire was sent to all third- and fourth-year medical students at our institution in order to assess their objective ability to select appropriate imaging studies and interpret basic imaging findings, as well as evaluate their subjective attitudes and comfort level with radiology topics. Statistical analysis compared students who completed the RSCP to non-RSCP controls. RESULTS: A total of 54 students responded to the survey (34 had previously completed the RSCP). RSCP participants were significantly more likely to select appropriate imaging workups and correctly interpret imaging findings compared to controls (p < 0.001). Furthermore, RSCP participants reported significantly higher confidence in their ability to order imaging (p < 0.001) and significantly higher satisfaction with their radiology education (p < 0.001). RSCP participants were less likely to agree with negative stereotypes regarding radiology and reported more favorable perceptions of the field. CONCLUSION: Preclinical radiology-driven medical student education programs like the RSCP offer the potential for lasting improvements in students' understanding of and attitudes toward radiology as a field. We believe that such programs will help address challenges facing the field of radiology regarding recruitment, diversity, and interdisciplinary understanding.

Subinternship in Diagnostic Radiology: Bringing the Shadowers Out of the Shadows.

RATIONALE AND OBJECTIVES: Diagnostic radiology subinternships are uncommon. We started a diagnostic radiology subinternship at our institution in 2020 and present 3 years of data assessing the impact of the course on students' perceptions of and interest in diagnostic radiology. MATERIALS AND METHODS: The initial course design consisted of daily shadowing shifts, small group lectures with attending radiologists, asynchronous self-paced learning assignments, an ultrasound skills session, multidisciplinary tumor board attendance, and completion of 2 formal case presentations. "Junior resident" shifts, where students dictated studies under attending supervision, an emergency radiology call shift, and an ultrasound procedures shift were subsequently added in response to student feedback. Students were asked to complete surveys before and after completing the course. RESULTS: Forty-seven fourth-year medical students completed the course over 3 years. The first 2 groups were predominantly male, whereas the third group showed near even gender representation (54% male). 21 (45%) chose to apply to diagnostic radiology for residency. Student reported interest in diagnostic radiology as a career, valuation of diagnostic radiology as a specialty, comfort with imaging interpretation, and perceptions of the availability of patient interaction and procedures in diagnostic radiology all significantly increased after participation in the course. Students ranked the junior resident shifts and small group attending lectures as the most valuable course components. CONCLUSION: Implementation of a diagnostic radiology subinternship significantly improved students' interest in and perceptions of the field. We encourage the creation of similar courses in other radiology departments and stress the importance of active learning experiences.

Blunt Cerebrovascular Injury: Are We Overscreening Low-Mechanism Trauma?

BACKGROUND AND PURPOSE: Screening patients with trauma for blunt cerebrovascular injury with neck CTA is a common practice, but there remains disagreement regarding which patients should be screened. We reviewed adult blunt cerebrovascular injury data from a level 1 trauma center to investigate whether screening is warranted in low-mechanism trauma. MATERIALS AND METHODS: We reviewed all neck CTAs performed on adult trauma patients in the emergency department during the 2019 calendar year. Clinical and imaging risk factors for blunt cerebrovascular injury, trauma mechanism, initial neck CTA interpretations, results from subsequent CTA and DSA studies, antiplatelet and anticoagulant treatments, and outcome data were recorded. RESULTS: One thousand one hundred thirty-six neck CTAs met the inclusion criteria, of which 965 (85%) were interpreted as having negative findings; 125, as having indeterminate findings (11%); and 46, as having positive findings (4%). Review of subsequent imaging and clinical documentation led to classification of 40 indeterminate studies (32%) as true-positives and 85 (68%) as false-positives. Blunt cerebrovascular injury was identified in 77 (12.6%) cases meeting and in 9 (1.7%) cases not meeting the expanded Denver criteria. The subset of 204 low-mechanism trauma cases (ground-level falls, blunt assaults, and low-impact motor vehicle collisions) not meeting the expanded Denver criteria (18% of the entire data set) could have been excluded from screening with 1 questionable injury and 0 ischemic strokes missed and 12 false-positive cases prevented. CONCLUSIONS: We advocate reservation of blunt cerebrovascular injury screening in low-mechanism trauma for patients meeting the expanded Denver criteria. Further research is needed to determine the behavior of indeterminate cases and to establish criteria for separating true-positive from false-positive findings.

The Radiology Scholars Certificate Program: A Medical Education Learning Tool.

RATIONALE AND OBJECTIVES: The Radiology Scholars Certificate Program (RSCP) is an extracurricular program created for preclinical medical students to address disparities in radiology education and exposure during medical school. MATERIALS AND METHODS: The RSCP was designed as a year-long program for first- and second-year medical students. The 4 key components of the RSCP are: Exposure to radiology through shadowing, knowledge acquisition through self-paced case-based learning modules, knowledge application in interactive workshops, and completion of a scholarly project. Students are required to complete at least 3 hours of shadowing, attend at least 3 workshops, complete self-paced online modules, and complete a capstone project on a topic of their choosing. Pre- and post-program surveys were administered to assess trends in participants' perception of the field and imaging-related clinical knowledge. RESULTS: In the first year of the RSCP, 55% of the matriculating class enrolled and of those, 84% completed the program. Approximately half of participants were female. Participants demonstrated significant improvement in radiology knowledge, with average scores improving from 52.8% to 68.6% (p < .001) on the knowledge-related survey questions. Significant improvements were also observed in student-reported confidence with ordering and interpreting imaging studies and in their perceptions of the field. CONCLUSION: The RSCP is an effective tool for addressing deficits in radiology education and exposure during medical school. It is designed to be run by senior medical students under radiology resident and attending supervision. With motivated student and radiologist investment, the RSCP should be easily replicable in medical training programs worldwide.

Radiation dose reduction during neuroendovascular procedures.

AIM: To describe the impact of steps towards reduction of procedural doses of radiation during neuroendovascular procedures. METHODS: Phantom exposures under controlled circumstances were performed using a Rando-Alderson adult-sized head phantom. Customized imaging protocols were devised for pediatric and adult imaging and implemented in clinical use. Outcome data for estimated skin doses (ESD) and dose-area product (DAP) following pediatric and adult diagnostic and interventional procedures over 4.5 years were analyzed retrospectively. RESULTS: Dose estimates were reduced by 50% or more after introduction of customized imaging protocols in association with modification of personnel behavior compared with doses recorded with previously used vendor-recommended protocols. DISCUSSION: Substantial reductions in radiation use during neuroendovascular procedures can be achieved through a combination of equipment modification and operator behavior.

Clinical, histopathologic, and radiographic indicators of malignancy in head and neck paragangliomas.

OBJECTIVE: The goal of this study is to review our series of head and neck paragangliomas to identify factors that may help in predicting malignancy. STUDY DESIGN: Case series with chart review. SETTING: Academic medical center. SUBJECTS AND METHODS: Subjects with head and neck paragangliomas at our institution from 1976 to current were reviewed. In addition to statistical comparisons of epidemiologic factors, pathologic and radiographic characteristics were reviewed. RESULTS: Of the 84 subjects, there were seven malignant paragangliomas (8%). Age was found to be significantly different between the benign and malignant subgroups, with an average age of 54 ± 16 and 40 ± 12 years, respectively (P = 0.02). Pain was a presenting complaint in five patients with benign disease (6%), and five of the seven malignant patients (71%) presented with pain, showing a significant association between pain and disease type (P < 0.0001). The odds ratio for a patient with pain having a malignant tumor was 36 (95% CI: 5.5-234). Enlarging neck mass was noted in all cases of malignant disease, but only in 31 percent of cases of benign disease (P < 0.0001). In a secondary analysis of carotid body tumors alone, enlarging neck mass was not found to be significant between benign and malignant disease (P = 0.14). However, pain continued to be significantly different, with 67 percent of malignant lesions demonstrating pain, compared with only 11 percent of benign lesions (P = 0.01). CONCLUSION: This study suggests that pain, a rapidly enlarging neck mass, and younger age are predictive factors of underlying malignancy, which should prompt one to consider an aggressive diagnostic and management approach.

Pediatric head injury prediction: investigating the distance between the skull and the brain using medical imaging - biomed 2009.

Injuries caused by Motor Vehicle Crashes (MVCs) are the leading cause of death and head injury for children in the United States. Improved finite element models that incorporate the correct size and shape of the pediatric brain and skull with current injury prevention metrics would improve the prediction of such pediatric head injuries. As an individual ages the shape of his/her brain, skull and meninges change with age. An accurate model needs to incorporate the interactive nature of these changes throughout pediatric development. The focus of this study is to quantify how the thickness and volume of the Cerebral Spinal Fluid (CSF) layer change with age in the pediatric population. The results of this study and others will be incorporated in creating a pediatric finite element model at various ages. This model may then be used by the automotive industry or in the study and analysis of shaken baby syndrome (SBS). The data-set consisted of fifty-nine individuals ranging in age from newborn to twenty-one years of age. Data was collected on the thickness of the CSF layer on the MR scans by taking forty measurements at specified points on three slices for each individual. The volume of the CSF layer was also quantified by making a mask of the CSF layer on all individuals. Both the thickness measurements and the volume analyses were then normalized utilizing a centroid value for each individual. Both the CSF thickness measurements and the volume analyses show a general logistic decrease in the amount of CSF from infancy to twenty-one years of age. Large CSF variation between individuals of the same age was observed; thus, future studies should utilize a longitudinal cohort study to control for individual differences in CSF. Sexual dimorphism in the size and shape of the CSF layer should also be investigated.

Age and gender based biomechanical shape and size analysis of the pediatric brain.

Injuries caused by motor vehicle crashes (MVCs) are the leading cause of head injury and death for children in the United States. This study aims to describe the shape and size (morphologic) changes of the cerebrum, cerebellum, brainstem, and ventricles of the pediatric occupant to better predict injury and assess how these changes affect finite element model (FEM) response. To quantify morphologic differences in the brain, a Generalized Procrustes Analysis (GPA) with a sliding landmark method was conducted to isolate morphologic changes using magnetic resonance images of 63 normal subjects. This type of geometric morphometric analysis was selected for its ability to identify homologous landmarks on structures with few true landmarks and isolate the shape and size of the individuals studied. From the resulting landmark coordinates, the shape and size changes were regressed against age to develop a model describing morphologic changes in the pediatric brain as a function of age. The most statistically significant shape change was in the cerebrum with p-values of 0.00346 for males and 0.00829 for females. The age-based model explains over 80% of the variation in size in the cerebrum. Using size and shape models, affine transformations were applied to the SIMon FEM to determine differences in response given differences in size and size plus shape. The geometric centroid of the elements exceeding 15% strain was calculated and compared to the geometric centroid of the entire structure. Given the same Haversine pulse, the centroid location, a metric for the spatial distribution of the elements exceeding an injury threshold, varied based on which transformation was applied to the model. To assess the overall response of the model, three injury metrics were examined to determine the magnitude of the metrics each element sustained and the overall volume of elements that experienced that value. These results suggested that the overall response of the model was driven by the variation in size, with little variation due to changes in shape. This study demonstrates a new methodology to quantify the shape and size variation of the brain from infancy to adulthood. The use of the changes in shape and size when applied to a FEM suggests that there are differences in the spatial distribution of the elements that exceed a specific threshold based on shape but the overall volume of elements experiencing the specified magnitude was more dependent on the changes in the size of the model with little change due to shape.

Geometric scaling factors for the pediatric brainstem.

Injuries caused by motor vehicle crashes (MVCs) are the leading cause of death for children in the United States as well as the leading cause of head injury. Improved finite element models that integrate the correct shape of the pediatric brain with current injury prediction metrics would improve occupant response prediction for the pediatric occupant. The focus of this study is the improvement of geometric scaling factors for the brainstem to adapt current adult brain models to a pediatric model. The method used to assess shape change for this study was a geometric morphometric analysis technique. A sliding landmark form of a general Procrustes analysis was selected for its ability to compare curved structures with few true landmarks. The dataset consisted of fifty-nine individuals ranging in age from newborn to twenty-one years of age with groups specified at newborn, three months, six months, one year, three years, six years, ten years, fifteen years, and twenty-one years of age. Data was collected by outlining the structure on transverse and sagittal scans of magnetic resonance images and then creating a landmark dataset with a user-defined number of points for each individual. Once all individuals had the same number of landmarks, these points are allowed to slide on planes tangent to the surface until a value described as bending energy is minimized relative to an iteratively computed mean configuration from a Generalized Procrustes Analysis. A General Procrustes Analysis was completed for this data set to determine the shape differences between the age groups. Then, the coordinate locations were regressed onto age, and this analysis resulted in a model that predicted landmark locations based on age. From this model, the dimensions of the brainstem were calculated using the specified age groups. The final step was taking the dimensions of the predicted twenty-one year old model as the base and calculating a geometric scaling factor for shape, without including changes in size, for each age group. To assess the statistical significance of the process, permutation tests with 100,000 iterations were performed with resulting p-values of 0.17177 for a linear regression and 0.13467 for a quadratic regression of landmark location as a function of age.

Age thresholds for increased mortality of three predominant crash induced head injuries.

Trauma in the US's increasingly aged population will pose medical, engineering, and legislative challenges in the coming decade. This study sought to identify the age threshold of maximal risk for patients with the three most common isolated types of head injuries from motor vehicle crashes (MVCs). Receiver-operator characteristic analysis was used to identify the quantitative age threshold associated with increased mortality for the three most common MVC-induced types of head injuries. For each injury, an algorithm using multivariable logistic regression modeling was implemented to examine mortality as a function of age, adjusted for the GCS motor score and patient gender. The age threshold that maximized the area under the receiver operator characteristic curve (AUROC) was identified and the curve examined. The increased adjusted odds ratio (AOR) for death associated with each threshold was estimated along with 95% confidence intervals. Data used was from the American College of Surgeons National Trauma Data Bank (NTDB) version 7, Motor Vehicle Crash cases from Jan 1, 2001 to Dec 31, 2006. Three types of head injuries were of a sufficiently high incidence and severity level to be included in the study; the AIS 140684.3 (Cerebrum, Subarachnoid Hemorrhage, n=499), AIS 140650.4 (Cerebrum, Subdural Hematoma NFS, n=273), and AIS 140629.4 (Hematoma/Hemorrhage, Not Further Specified, n=123). The age thresholds are 58 (AOR=4.12, 95% CI 1.21-14.07, p=0.024), 54 (AOR=4.71, 95% CI 1.08-20.46, p=0.039) and 47 (AOR=15.44, 95% CI 2.94-81.2, p=0.001), respectively. Maximal AUROC values ranged from 0.89-0.93. This data along with data on injury mechanism has been used to provide information on the ideal 'threshold' beyond which age becomes an important factor for these three types of head injuries. This is the first study to quantitatively estimate the mortality threshold age for common isolated head injuries. This study has potential implications in the arena of safety design for the elderly, automated crash notification, and auto safety legislation.

Analysis of pediatric head anthropometry using computed tomography for application to head injury prediction.

Motor vehicle accidents are the leading cause of death of people between one and thirty-four years of age in the U.S., and head trauma is a significant lethal injury in such cases. During a motor vehicle crash, the head often experiences blunt force trauma from impacts with seat backs, steering wheels, windows, and dashes. The resulting injuries can cause skull fractures, concussions, bleeding and swelling of the brain. Crash test dummies and finite element models are often used to study the nature and likelihood of injury during a crash, but these are currently based on scaled versions of a standard, 50th percentile male. This approach fails to accurately capture the size and shape variation in even the adult population, but may be especially inappropriate for modeling pediatric head injuries where, for instance, infants have fontanelles and reduced bone structure. In this presentation, an approach for modification of a finite element model of the human head based on 50th percentile male dimensions and representing the skull, brain, dura/CSF layer, and Falx Celebri, that will incorporate the anatomical and nonlinear morphological changes observed in pediatric skulls during ontogeny. Using 96 CT scans of normal pediatric skulls, landmark coordinate points are identified to map the changes in skull shape and size as aging occurs. The pediatric skull changes rapidly in size and shape during the first two years of age. Using this information, a pediatric finite element head model will be created, using parametric mesh generation software, to measure head injury in children in a motor vehicle crash.