Association of fractal dimension and other retinal vascular network parameters with cognitive performance and neuroimaging biomarkers: The Multi-Ethnic Study of Atherosclerosis (MESA).

INTRODUCTION: Retinal vascular network changes may reflect the integrity of the cerebral microcirculation, and may be associated with cognitive impairment. METHODS: Associations of retinal vascular measures with cognitive function and MRI biomarkers were examined amongst Multi-Ethnic Study of Atherosclerosis (MESA) participants in North Carolina who had gradable retinal photographs at Exams 2 (2002 to 2004, n = 313) and 5 (2010 to 2012, n = 306), and detailed cognitive testing and MRI at Exam 6 (2016 to 2018). RESULTS: After adjustment for covariates and multiple comparisons, greater arteriolar fractal dimension (FD) at Exam 2 was associated with less isotropic free water of gray matter regions (ß = -0.0005, SE = 0.0024, p = 0.01) at Exam 6, while greater arteriolar FD at Exam 5 was associated with greater gray matter cortical volume (in mm3 , ß = 5458, SE = 20.17, p = 0.04) at Exam 6. CONCLUSION: Greater arteriolar FD, reflecting greater complexity of the branching pattern of the retinal arteries, is associated with MRI biomarkers indicative of less neuroinflammation and neurodegeneration.

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.

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.

Study of the Natural Crystalline Lens Characteristics Using Dual-Energy Computed Tomography.

There is a paucity of radiologic literature regarding age-related cataract, and little is known about any differences in the imaging appearance of the natural crystalline lens on computed tomography (CT) exams among different demographic groups. In this retrospective review of 198 eyes in 103 adults who underwent dual-energy computed tomography (DECT) exams of the head, regions of interest spanning 3−5 mm were placed over the center of the lens, and the x-ray attenuation of each lens was recorded in Hounsfield Units (HU) at 3 energy levels: 40 keV, 70 keV, and 190 keV. Generalized estimating equations (GEEs) were used to assess the association of clinical or demographic data with lens attenuation. The mean HU values were significantly lower for the older vs. younger group at 40 keV (GEE p-value = 0.022), but there was no significant difference at higher energy levels (p > 0.05). Mean HU values were significantly higher for females vs. males and non-whites vs. non-Hispanic whites at all 3 energy levels in bivariate and multivariable analyses (all p-value < 0.05). There was no significant association between lens attenuation and either diabetes or smoking status. The crystalline lens of females and non-whites had higher attenuation on DECT which may suggest higher density or increased concentration of materials like calcium and increased potential for cataract formation. Given the large scope of cataracts as a cause of visual impairment and the racial disparities that exist in its detection and treatment, further investigation into the role of opportunistic imaging to detect cataract formation is warranted.

Cranial Nerve Anatomy Using a Modular and Multimodal Radiologic Approach.

Introduction: Medical students often struggle with learning cranial nerve anatomy. Typically, cranial nerve anatomy is taught using didactic lectures and textbook illustrations, often leaving students frustrated. Methods: We developed a multimodal radiologic approach to teaching cranial nerve anatomy. First, 150 students were presented with carefully curated preclass material from which to prepare. Next, they received a didactic lecture that was recorded for them to revisit on their own time. Last, students worked in groups in a lab setting with expert radiologists to identify the cranial nerves and related anatomy and learn about some basic pathophysiology. We used a pretest and posttest to examine the effectiveness of our teaching methods and a survey to measure students' satisfaction. Results: Student knowledge of cranial nerve structure was significantly improved after our module, with quiz scores increasing from 4.6 to 6.8 out of 9.0 (p < .001). In addition, students reported feeling more confident in their knowledge of the material and offered high satisfaction scores. Discussion: The breadth of knowledge covered during the preclinical training years continues to expand despite stable or even contracted durations of training, requiring knowledge to be delivered in an ever more efficient manner. Ultimately, the multimodal pedagogy used by our resource leads to students who are more confident and engaged in their learning, resulting in increased knowledge.

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.

The imaging diagnosis of cholecystitis in the adult ED: a comparative multi-reader, multivariable analysis of CT and US image features.

PURPOSE: The purposes of this study are (1) to utilize multivariable logistic regression in order to evaluate which image feature combination is most predictive in the diagnosis of cholecystitis for computed tomography (CT) and ultrasound (US) in adult ED patients and (2) to use these results to compare the accuracy of CT and US. METHODS: For RUQ pain patients undergoing US and CT at the same visit, multiple image features were evaluated independently by 2 radiologists blinded to additional data. Inter-reader variability was measured with the Kappa statistic. Sonographic Murphy's sign (SMS) information was obtained from original reports. Multivariable logistic regression was utilized to develop optimal predictive models for each modality. For US, models with/without SMS were compared to establish its relative value. RESULTS: 446 patients met inclusion criteria. For CT, the combination of cholelithiasis, short-axis gallbladder diameter > 3 cm, pericholecystic fluid or inflammation, and mural thickening > 3 mm provided the optimal model for both readers. For US, the optimal model included cholelithiasis, short-axis diameter > 3 cm, mural heterogeneity/striation, and sludge/debris for both readers. Kappa = 0.79-0.96 for included image features. For both readers, CT and US models had equivalent diagnostic performances; the SMS did not contribute significantly to US models. CONCLUSION: For a diagnosis of cholecystitis in the ED, (1) the optimal image feature combination for CT is cholelithiasis, short-axis diameter > 3 cm, pericholecystic fluid or inflammation, mural thickening > 3 mm; and cholelithiasis, short-axis diameter > 3 cm, mural heterogeneity/striation, sludge/debris for US; (2) CT and US have equivalent diagnostic performance; (3) inter-reader reliability is substantial to excellent for utilized image features; (4) the SMS does not affect US model accuracy.

Role of Ultrasound and CT in the Workup of Right Upper Quadrant Pain in Adults in the Emergency Department: A Retrospective Review of More Than 2800 Cases.

OBJECTIVE. The purpose of this study was to compare ultrasound and CT in the diagnostic evaluation of right upper quadrant pain in adults in the emergency department. MATERIALS AND METHODS. A retrospective review was conducted of adult emergency department encounters for right upper quadrant pain over a 5-year period, excluding those for prior cholecystectomy, current pregnancy, and trauma. Imaging study reports were reviewed for gallbladder and nongallbladder explanations of right upper quadrant pain and were considered positive for cholecystitis when two or more supportive features were present. Encounter outcomes were evaluated on the basis of pathology data and clinical management. RESULTS. Among the encounters, 2859 met the study inclusion criteria, and 18% met the study definition of cholecystitis by pathologic or clinical criteria. The following metrics showed no statistically significant difference between ultrasound and CT, respectively: sensitivity, 61% and 55%; specificity, 91% and 92%; positive predictive value, 63% and 63%; and negative predictive value, 91% and 90%. Both modalities were performed in 20% of encounters. In the subgroup analysis, ultrasound showed an acute nongallbladder abnormality that was missed at a preceding CT examination in only 1 of 238 cases (0.4%). CT showed an acute nongallbladder abnormality missed at a preceding ultrasound examination in 103 of 322 cases (32%). CONCLUSION. CT is noninferior to ultrasound in both ruling in and ruling out the diagnosis of cholecystitis in adult patients undergoing emergency evaluation of right upper quadrant pain and offers the advantage of depicting acute nongallbladder abnormalities.

How accurate is the label "allergic to iodinated contrast agents"?

BACKGROUND: Iodinated contrast agents (ICAs) are crucial to the use of many imaging studies. Reported allergies to ICAs in the medical record can interfere with optimal diagnostic imaging workups. PURPOSE: To investigate the accuracy with which the label "allergic to ICAs" is applied. MATERIAL AND METHODS: The medical records of 500 patients labeled "allergic to ICAs" at a single tertiary care hospital were reviewed. Patients were separated into three groups based on documentation in their medical records, as follows: Group 1, documented hypersensitivity reaction to ICAs; Group 2, documented ICA exposure with non-hypersensitivity adverse event (Group 2a) or without documented reaction (Group 2b); and Group 3, no documented prior exposure to an ICA. We then further reviewed the EMR to determine whether or not patients had subsequent administration of an ICA, whether or not they were given specific premedication, and whether or not they had a subsequent ICA-related event. RESULTS: A total of 16.6% of patients (n = 83) listed as "allergic to ICAs" had a documented hypersensitivity reaction following ICA administration (Group 1) while 58.6% (n = 293) of patients (Group 2) had a documented exposure to ICAs with either: (i) a non-hypersensitivity adverse event (23.5%, n = 69) or (ii) no record of a reaction to ICAs (76.5%, n = 224). The remaining 24.8% (n = 124), Group 3, had no record of exposure to an ICA, yet still carried the label. CONCLUSION: The majority of patients carrying the label "allergic to ICAs" had no record of a prior hypersensitivity reaction to ICAs.

Computed tomography fluoroscopy versus conventional computed tomography guidance for biopsy of intrathoracic lesions: a retrospective review of 1143 consecutive procedures.

PURPOSE: To compare the success rates, complication rates, and radiation doses of conventional computed tomography (CCT) versus computed tomography with fluoroscopy (CTF) during image-guided percutaneous needle biopsies of intrathoracic lesions. MATERIALS AND METHODS: We conducted a retrospective analysis of 1143 consecutive intrathoracic biopsies performed under computed tomography guidance at a single tertiary care center. For each procedure we recorded patient age and sex, lesion size and location, and radiation dose administered to the patient. Thereafter, appropriate tests of statistical significance were applied to compare rates of success, complications, and radiation between CCT and CTF guidance. RESULTS: After correcting for lesion size, CTF was associated with an odds ratio (OR) of 6.07 [95% confidence interval (CI): 2.23-16.50] for technical procedural success, an OR of 0.79 (95% CI: 0.55-1.15) for fine-needle aspiration success, an OR of 2.11 (95% CI: 1.02-4.38) for core-needle biopsy success, and an OR of 1.45 (95% CI: 1.00-2.21) for overall success when compared with CCT. CTF was associated with an OR of 1.10 (95% CI: 0.35-3.48) for complications when compared with CCT. Mean dose-length product per procedure was 1332 mGy cm for CCT and 1730 mGy cm for CTF (P=0.027). CONCLUSIONS: CCT and CTF are both valuable tools for intrathoracic biopsy. CTF improves technical and core-needle biopsy success at the expense of higher radiation doses to the patient. Operator confidence with CCT and CTF in light of lesion characteristics should guide the choice to select one over the other.

Searching for the optimal data partitioning strategy in mitochondrial phylogenomics: a phylogeny of Acridoidea (Insecta: Orthoptera: Caelifera) as a case study.

One of the main challenges in analyzing multi-locus phylogenomic data is to find an optimal data partitioning strategy to account for variable evolutionary histories of different loci for any given dataset. Although a number of studies have addressed the issue of data partitioning in a Bayesian phylogenetic framework, such studies in a maximum likelihood framework are comparatively lacking. Furthermore, a rigorous statistical exploration of possible data partitioning schemes has not been applied to mitochondrial genome (mtgenome) data, which provide a complex, but manageable platform for addressing various challenges in analyzing phylogenomic data. In this study, we investigate the issue of data partitioning in the maximum likelihood framework in the context of the mitochondrial phylogenomics of an orthopteran superfamily Acridoidea (Orthoptera: Caelifera). The present study analyzes 34 terminals representing all 8 superfamilies within Caelifera, which includes newly sequenced partial or complete mtgenomes for 11 families. Using a new partition-selection method implemented in the software PartitionFinder, we compare a large number of data partitioning schemes in an attempt to identify the most effective method of analyzing the mtgenome data. We find that the best-fit partitioning scheme selected by PartitionFinder is superior to any a priori schemes commonly utilized in mitochondrial phylogenomics. We also show that over-partitioning is often detrimental to phylogenetic reconstruction. A comparative analysis of mtgenome structures finds that the tRNA gene rearrangement between cytochrome c oxidase subunit II and ATP synthase protein 8 does not occur in the most basal caeliferan lineage Tridactyloidea, suggesting that this gene rearrangement must have evolved at least in the common ancestor of Tetrigoidea and Acridomorpha. We find that mtgenome data contain sufficient phylogenetic information to broadly resolve the relationships across Acridomorpha and Acridoidea.

Uncovering historical signature of mitochondrial DNA hidden in the nuclear genome: the biogeography of Schistocerca revisited.

Inadvertent coamplification of nuclear mitochondrial pseudogenes (numts) is a serious problem in mitochondrial systematics, but numts can also be a valuable source of information because they represent ancient forms of mtDNA. We present a conceptual framework of numt accumulation, which states that in a given species there can be two types of numts, synaponumts and autaponumts, resulting from integration occurring respectively before and after a speciation event. In a given clade, a species that diverged early can only have its own autaponumts as well as synaponumts that were already present in the genome of the last common ancestor. A species that diverged more recently may, however, have many different synaponumts integrated at each different divergence as well as its own autaponumts. Therefore it is possible to decipher the evolutionary history of a species based on the phylogenetic distribution of numts in a simultaneous analysis of numts and extant mtDNA. In this study, we test this idea empirically in the context of addressing a controversial question regarding the biogeography of the grasshopper genus Schistocerca Stål (Orthoptera: Acrididae), based on numts of the cytochrome c oxidase subunit I (COI) gene. We find that our empirical data can be explained adequately by our conceptual framework, and that the phylogenetic distribution of COI numts reveals intricate evolutionary histories about past speciation events that are otherwise difficult to detect using conventional markers. Our study strongly favours the Old World origin of the desert locust, Schistocerca gregaria and the New World Schistocerca species are descendants from an ancestral gregaria-like species that colonized the New World via westward transatlantic flight. However, the phylogenetic distribution of S. gregaria numts raises a distinct possibility that there might have been multiple founding events from Africa to America to give rise to the present-day diversity of the genus. This is a case study for a creative use of numts as molecular fossils, and we demonstrate that numts provide an interesting and powerful phylogenetic signal, much more than what extant mtDNA or nuclear gene sequences might be able to provide.

Mitochondrial genomics in Orthoptera using MOSAS.

We present complete mitochondrial genomes (mitogenomes) for three orthopterans (Xyleus modestus, Physemacris variolosa, and Ellipes minuta) and describe MOSAS (manipulation, organization, storage, and analysis of sequences), software we developed to facilitate annotation and analysis. We analyze the base composition, start and stop codons, non-coding regions, and gene order among these and 18 other orthopteran mitogenomes from GenBank and reconstruct a phylogeny of Orthoptera. We propose a tetranucleotide start codon for cox1, and hypothesize that the tRNA(Asp)-tRNA(Lys) rearrangement is a synapomorphy for Acridomorpha, but not Caelifera. We further describe MOSAS, user-friendly software we used for this analysis. MOSAS streamlines sequence data storage, organization, annotation, and alignment, and provides convenient search tools for dataset construction and a robust annotation engine particularly suited to annotating mitogenomes (available at http://mosas.byu.edu).