Cost-Effectiveness of CT, CTA, MRI, and Specialized MRI for Evaluation of Patients Presenting to the Emergency Department With Dizziness.

BACKGROUND. Underlying stroke is often misdiagnosed in patients presenting with dizziness. Although such patients are usually ineligible for acute stroke treatment, accurate diagnosis may still improve outcomes through selection of patients for secondary prevention measures. OBJECTIVE. The purpose of our study was to investigate the cost-effectiveness of differing neuroimaging approaches in the evaluation of patients presenting to the emergency department (ED) with dizziness who are not candidates for acute intervention. METHODS. A Markov decision-analytic model was constructed from a health care system perspective for the evaluation of a patient presenting to the ED with dizziness. Four diagnostic strategies were compared: noncontrast head CT, head and neck CTA, conventional brain MRI, and specialized brain MRI (including multiplanar high-resolution DWI). Differing long-term costs and outcomes related to stroke detection and secondary prevention measures were compared. Cost-effectiveness was calculated in terms of lifetime expenditures in 2022 U.S. dollars for each quality-adjusted life year (QALY); deterministic and probabilistic sensitivity analyses were performed. RESULTS. Specialized MRI resulted in the highest QALYs and was the most cost-effective strategy with US$13,477 greater cost and 0.48 greater QALYs compared with noncontrast head CT. Conventional MRI had the next-highest health benefit, although was dominated by extension with incremental cost of US$6757 and 0.25 QALY; CTA was also dominated by extension, with incremental cost of US$3952 for 0.13 QALY. Non-contrast CT alone had the lowest utility among the four imaging choices. In the deterministic sensitivity analyses, specialized MRI remained the most cost-effective strategy. Conventional MRI was more cost-effective than CTA across a wide range of model parameters, with incremental cost-effectiveness remaining less than US$30,000/QALY. Probabilistic sensitivity analysis yielded similar results as found in the base-case analysis, with specialized MRI being more cost-effective than conventional MRI, which in turn was more cost-effective than CTA. CONCLUSION. The use of MRI in patients presenting to the ED with dizziness improves stroke detection and selection for subsequent preventive measures. MRI-based evaluation leads to lower long-term costs and higher cumulative QALYs. CLINICAL IMPACT. MRI, incorporating specialized protocols when available, is the preferred approach for evaluation of patients presenting to the ED with dizziness, to establish a stroke diagnosis and to select patients for secondary prevention measures.

CT With CTA Versus MRI in Patients Presenting to the Emergency Department With Dizziness: Analysis Using Propensity Score Matching.

BACKGROUND. CT with CTA is widely used to exclude stroke in patients with dizziness, although MRI has higher sensitivity. OBJECTIVE. The purpose of this article was to compare patients presenting to the emergency department (ED) with dizziness who undergo CT with CTA alone versus those who undergo MRI in terms of stroke-related management and outcomes. METHODS. This retrospective study included 1917 patients (mean age, 59.5 years; 776 men, 1141 women) presenting to the ED with dizziness from January 1, 2018, to December 31, 2021. A first propensity score matching analysis incorporated demographic characteristics, medical history, findings from the review of systems, physical examination findings, and symptoms to construct matched groups of patients discharged from the ED after undergoing head CT with head and neck CTA alone and patients who underwent brain MRI (with or without CT and CTA). Outcomes were compared. A second analysis compared matched patients discharged after CT with CTA alone and patients who underwent specialized abbreviated MRI using multiplanar high-resolution DWI for increased sensitivity for posterior circulation stroke. Sensitivity analyses were performed involving MRI examinations performed as the first or only neuroimaging examination and involving alternative matching and imputation techniques. RESULTS. In the first analysis (406 patients per group), patients who underwent MRI, compared with patients who underwent CT with CTA alone, showed greater frequency of critical neuroimaging results (10.1% vs 4.7%, p = .005), change in secondary stroke prevention medication (9.6% vs 3.2%, p = .001), and subsequent echocardiography evaluation (6.4% vs 1.0%, p < .001). In the second analysis (100 patients per group), patients who underwent specialized abbreviated MRI, compared with patients who underwent CT with CTA alone, showed greater frequency of critical neuroimaging results (10.0% vs 2.0%, p = .04), change in secondary stroke prevention medication (14.0% vs 1.0%, p = .001), and subsequent echocardiography evaluation (12.0% vs 2.0%, p = .01) and lower frequency of 90-day ED readmissions (12.0% vs 28.0%, p = .008). Sensitivity analyses showed qualitatively similar findings. CONCLUSION. A proportion of patients discharged after CT with CTA alone may have benefitted from alternative or additional evaluation by MRI (including MRI using a specialized abbreviated protocol). CLINICAL IMPACT. Use of MRI may motivate clinically impactful management changes in patients presenting with dizziness.

Clinical criteria to exclude acute vascular pathology on CT angiogram in patients with dizziness.

BACKGROUND: Patients presenting to the emergency department (ED) with dizziness may be imaged via CTA head and neck to detect acute vascular pathology including large vessel occlusion. We identify commonly documented clinical variables which could delineate dizzy patients with near zero risk of acute vascular abnormality on CTA. METHODS: We performed a cross-sectional analysis of adult ED encounters with chief complaint of dizziness and CTA head and neck imaging at three EDs between 1/1/2014-12/31/2017. A decision rule was derived to exclude acute vascular pathology tested on a separate validation cohort; sensitivity analysis was performed using dizzy "stroke code" presentations. RESULTS: Testing, validation, and sensitivity analysis cohorts were composed of 1072, 357, and 81 cases with 41, 6, and 12 instances of acute vascular pathology respectively. The decision rule had the following features: no past medical history of stroke, arterial dissection, or transient ischemic attack (including unexplained aphasia, incoordination, or ataxia); no history of coronary artery disease, diabetes, migraines, current/long-term smoker, and current/long-term anti-coagulation or anti-platelet medication use. In the derivation phase, the rule had a sensitivity of 100% (95% CI: 0.91-1.00), specificity of 59% (95% CI: 0.56-0.62), and negative predictive value of 100% (95% CI: 0.99-1.00). In the validation phase, the rule had a sensitivity of 100% (95% CI: 0.61-1.00), specificity of 53% (95% CI: 0.48-0.58), and negative predictive value of 100% (95% CI: 0.98-1.00). The rule performed similarly on dizzy stroke codes and was more sensitive/predictive than all NIHSS cut-offs. CTAs for dizziness might be avoidable in 52% (95% CI: 0.47-0.57) of cases. CONCLUSIONS: A collection of clinical factors may be able to "exclude" acute vascular pathology in up to half of patients imaged by CTA for dizziness. These findings require further development and prospective validation, though could improve the evaluation of dizzy patients in the ED.

Scenarios to improve CT head utilization in the emergency department delineated by critical results reporting.

PURPOSE: Increasing use of advanced imaging in the emergency department (ED) has resulted in higher cost without better outcomes. Our goal was to evaluate the yield of CT head exams by scenario to guide efforts at improving patient selection. METHODS: We performed a retrospective study at an academic medical center over 4 years (1/1/2014-12/31/2017). The chief complaint, imaging order, and exam result text were obtained for all adult ED encounters. For the 50 most common chief complaints leading to CT head exams, the ratio of exams to total encounters and ratio of critical results to imaging studies were calculated. Significant difference in "yield" was assessed via binomial test. RESULTS: Over 708,145 adult ED encounters, 58,783 CT head exams were ordered, with an overall critical result yield of 8.0%. The three most common chief complaints had higher yield (p < 0.05): altered mental status (9.8%), fall (9.7%), and new headache (10.1%). Lower yield (p < 0.05) was found for 19 chief complaints: dizziness (6.2%), falls in patients > 65 years old (7.1%), syncope (5.3%), seizure with known epilepsy (4.8%), chest pain (3.7%), head injury (4.9%), headache re-evaluation (7.0%), alcohol intoxication (2.5%), fatigue (6.5%), headache-recurrent or in the setting of known migraines (5.2%), hypertension (4.4%), lethargy (5.8%), loss of consciousness (5.3%), migraine (3.2%), psychiatric evaluation (2.9%), near syncope (4.6%), drug problem (3.1%), symptomatically decreased blood sugar (3.2%), and suicidal (1.7%). CONCLUSION: Our study provides a priority list of low yield scenarios of CT head use for improvement of patient selection.

Head and Neck CTA Utilization: Analysis of Ordering Frequency and Nonroutine Results Communication, With Focus on the 50 Most Common Emergency Department Clinical Presentations.

BACKGROUND. Utilization of head and neck CTA in the emergency department (ED) has grown disproportionately to other neuroimaging examinations. OBJECTIVE. The purpose of this article was to characterize utilization of head and neck CTA in the ED, comparing utilization and frequency of nonroutine results communication among patients' chief concerns. METHODS. All adult ED visits for a single health care system from January 2014 to December 2017 were retrospectively reviewed. Variables recorded included chief concerns, whether head and neck CTA was performed, and, if so, whether the report documented nonroutine results communication. The 50 chief concerns resulting in the highest number of head and neck CTA examinations were identified. Frequencies of head and neck CTA ordering and of nonroutine results communication were calculated. A subset of reports documenting nonroutine communication were manually reviewed. RESULTS. Head and neck CTA was ordered in 2.5% (17,903) of 708,145 ED visits in 236,476 patients (mean age, 49.8 ± 20.5 [SD] years; 110,952 men, 125,521 women, 3 unknown sex). Head and neck CTA was ordered for 833 distinct chief concerns. Nonroutine results communication was documented for 17.6% (3155/17,903) of examinations. Among the 50 chief concerns associated with the highest number of examinations, frequency of ordering head and neck CTA ranged from less than 0.5% (five concerns) to 55.2% (stroke code), and frequency of nonroutine communication ranged from 5.6% (transient ischemic attack) to 67.5% (unresponsive). Chief concerns not among the 50 most common accounted for 50.0% (8956/17,903) of examinations; these exhibited a collective frequency of nonroutine communication of 4.8% (429/8956). Manual review of 11.1% (350/3155) of reports with a nonroutine communication indicated an acute finding related to the indication in 51.1%, nonemergent but potentially explanatory finding in 14.0%, incidental finding in 28.0%, and communication of negative results in 6.9%. CONCLUSION. Head and neck CTA is ordered in 2.5% of ED visits for a wide range of chief concerns. Frequencies of ordering and of nonroutine results communication are highly variable among chief concerns. Acute indication-related findings account for half of nonroutine radiologist communications. CLINICAL IMPACT. Insight into patterns regarding head and neck CTA ordering and nonroutine results may help optimize patient selection and radiologist communications in the ED setting.

Pilot MRI-based strategies to improve the detection of stroke in patients with dizziness/vertigo.

Posterior strokes are frequently misdiagnosed as they present with non-specific complaints such as dizziness/vertigo. Emergency department (ED) practice often relies on CT/CTA to "exclude" infarct in such patients, providing false reassurance due to lower sensitivity of CT (42%) for stroke in the posterior circulation. We describe a pilot at our institution using a specialized MRI protocol with 95% sensitivity for posterior stroke, which may be used in place of CT/CTA or conventional MRI for stroke evaluation. Further development of this approach may help reduce the high rate of missed posterior stroke in patients presenting with dizziness.

Blind spots on CT imaging of the head: Insights from 5 years of report addenda at a single institution.

BACKGROUND: Errors of detection ("misses") are the major source of error in radiology. There is sparse prior literature describing patterns of detection error on CT head imaging. PURPOSE: The objective of this study was to gain insight to areas on CT head imaging where radiologists are most likely to miss clinically relevant findings. METHODS: We performed a cross-sectional study of consecutive reports of CT imaging of the head at a single institution spanning 5/1/2013-5/1/2018 (5 years). Detection errors described in addenda were categorized according to anatomic location, type of pathology, and potential impact on management. Blind spots were defined by the most common sites of missed findings. RESULTS: A total of 165,943 reports for CT head imaging were obtained. Addenda were found in 1658 (~1%) of reports, of which 359 (21.7%) described errors of detection. Within the extracranial soft tissues (n = 73) the most common "misses" were at incidentally imaged parotid glands and the frontal scalp. Within osseous structures (n = 149), blind spots included the nasal and occipital bones. Vascular lesions (n = 47) which passed detection were most common at the distal MCA, carotid terminus and sigmoid sinus/jugular bulb. No predisposition was seen for anatomic subsites within the CSF space (n = 60) and brain parenchyma (n = 65). CONCLUSIONS: Consistent patterns of blind spots are revealed. Radiologic teaching and search patterns to account for these sites of error may accelerate trainee competence and improve accuracy in the practice of radiology.

MRI of the Penis: Indications, Anatomy, and Pathology.

The purpose of this review is to discuss the role of magnetic resonance imaging (MRI) in the evaluation of penile pathology. Normal penile anatomy as well as the appearance of neoplastic and non-neoplastic entities on MRI will be reviewed. While ultrasound remains the first line imaging modality in evaluating most penile pathology, MR imaging has specific advantages owing to improved soft tissue resolution, ability to evaluate less accessible or complex anatomy (such as at the base of the penis), and the ability to detect subtle enhancement. Therefore, MRI is useful for when ultrasound and/or clinical findings are equivocal or incongruent. In addition, MR imaging is essential for preoperative surgical planning and is the imaging modality of choice in evaluating penile prostheses. The added value of MRI in these settings makes it an integral component to the management of many pathological entities affecting the penis.

Duodenal intussusception secondary to web presenting as recurrent pancreatitis in a 7-year-old girl.

Duodenal intussusception is a rare entity in children, with 32 cases reported in the English literature to our knowledge. Most reported cases are associated with endoluminal tubes or polyps, and the presenting symptoms are chronic and nonspecific. We report a case of duodenal intussusception in a 7-year-old girl secondary to a duodenal web and review the imaging findings.

P22 coat protein structures reveal a novel mechanism for capsid maturation: stability without auxiliary proteins or chemical crosslinks.

Viral capsid assembly and stability in tailed, dsDNA phage and Herpesviridae are achieved by various means including chemical crosslinks (unique to HK97), or auxiliary proteins (lambda, T4, phi29, and herpesviruses). All these viruses have coat proteins (CP) with a conserved, HK97-like core structure. We used a combination of trypsin digestion, gold labeling, cryo-electron microscopy, 3D image reconstruction, and comparative modeling to derive two independent, pseudoatomic models of bacteriophage P22 CP: before and after maturation. P22 capsid stabilization results from intersubunit interactions among N-terminal helices and an extensive "P loop," which obviate the need for crosslinks or auxiliary proteins. P22 CP also has a telokin-like Ig domain that likely stabilizes the monomer fold so that assembly may proceed via individual subunit addition rather than via preformed capsomers as occurs in HK97. Hence, the P22 CP structure may be a paradigm for understanding how monomers assemble in viruses like phi29 and HSV-1.