Assessing the productivity of PAs and NPs.

ABSTRACT: The improvement of healthcare efficiency and productivity is of international interest. Following an expansion phase of physician associate/assistant (PA) and NPs employment, the Department of Veterans Affairs (VA) assessed how and where they were being used. Using data from 134 VA medical centers, annual productivity was examined across 30 medical and surgical specialties spanning primary care, mental health, and surgery. PA productivity differences averaged 82 relative value units per full-time employee per year more than NPs, a difference of 4%. In general, PAs were found in higher productivity ranges than NP counterparts. PAs and NPs have statistically similar productivity levels in primary care and mental health. In specialty medicine and surgery, PAs average higher annual productivity than NPs. This analysis provides some utility for managers regarding workforce composition, given the relative productivity of two types of clinicians.

The Effect of Telehealth Services on Provider Productivity.

BACKGROUND: Telehealth services historically have played a small role in the provision of health care in the United States. However during the coronavirus disease 2019 (COVID-19) pandemic, public and private insurers rapidly expanded access to telehealth in order to reduce exposure and avoid transmission. It is unknown whether telehealth will become a more regular substitute for in-person care beyond the pandemic. OBJECTIVE: Our objective was to provide evidence on the value of telehealth by comparing the productivity of physicians and other specialized clinicians who provide telehealth with the productivity of those who do not. RESEARCH DESIGN: We conducted a retrospective data analysis of 17,705 unique providers in the areas of internal medicine, cardiology, dermatology, psychiatry, psychology, and optometry practicing in the US veterans affairs health care system during the period 2015 to 2018. For each year, we measured individual providers productivity by the total number of relative value units (RVUs) per full-time equivalent (FTE). We estimated the impact of providing telehealth on RVUs/FTE using fixed effects regression models estimated on a panel dataset of 58,873 provider-year observations and controlling for provider and patient characteristics. RESULTS: Overall provider productivity increased in veterans affairs over the period, particularly in cardiology and dermatology. Providers of telehealth had above average productivity by 124 RVUs/FTE, or ∼4% of average total provider productivity. For the highest quartile of telehealth providers, average productivity was 188 RVUs/FTE higher than productivity of other providers. CONCLUSION: Strategies that encourage long-term integration of telehealth into provider practices may contribute to overall health care value.

COVID-19 and cardiac arrhythmias: a global perspective on arrhythmia characteristics and management strategies.

BACKGROUND: Cardiovascular and arrhythmic events have been reported in hospitalized COVID-19 patients. However, arrhythmia manifestations and treatment strategies used in these patients have not been well-described. We sought to better understand the cardiac arrhythmic manifestations and treatment strategies in hospitalized COVID-19 patients through a worldwide cross-sectional survey. METHODS: The Heart Rhythm Society (HRS) sent an online survey (via SurveyMonkey) to electrophysiology (EP) professionals (physicians, scientists, and allied professionals) across the globe. The survey was active from March 27 to April 13, 2020. RESULTS: A total of 1197 respondents completed the survey with 50% of respondents from outside the USA, representing 76 countries and 6 continents. Of respondents, 905 (76%) reported having COVID-19-positive patients in their hospital. Atrial fibrillation was the most commonly reported tachyarrhythmia whereas severe sinus bradycardia and complete heart block were the most common bradyarrhythmias. Ventricular tachycardia/ventricular fibrillation arrest and pulseless electrical activity were reported by 4.8% and 5.6% of respondents, respectively. There were 140 of 631 (22.2%) respondents who reported using anticoagulation therapy in all COVID-19-positive patients who did not otherwise have an indication. One hundred fifty-five of 498 (31%) reported regular use of hydroxychloroquine/chloroquine (HCQ) + azithromycin (AZM); concomitant use of AZM was more common in the USA. Sixty of 489 respondents (12.3%) reported having to discontinue therapy with HCQ + AZM due to significant QTc prolongation and 20 (4.1%) reported cases of Torsade de Pointes in patients on HCQ/chloroquine and AZM. Amiodarone was the most common antiarrhythmic drug used for ventricular arrhythmia management. CONCLUSIONS: In this global survey of > 1100 EP professionals regarding hospitalized COVID-19 patients, a variety of arrhythmic manifestations were observed, ranging from benign to potentially life-threatening. Observed adverse events related to use of HCQ + AZM included prolonged QTc requiring drug discontinuation as well as Torsade de Pointes. Large prospective studies to better define arrhythmic manifestations as well as the safety of treatment strategies in COVID-19 patients are warranted.

The gap between what patients know and desire to learn about their cardiac implantable electronic devices.

BACKGROUND: Advancement of digital technology now allows patients to have access to data from their cardiac implantable electronic devices (CIEDs). However, patients' understanding regarding CIED data and perceived personal usability remain unclear. The present study is a prospective survey to examine patients' understanding of their CIEDs and their perception of what is important. METHODS: We screened 400 patients between July and December 2018 who presented to our outpatient clinic for a CIED interrogation. Patients received a one-page questionnaire asking baseline demographics, their perception about their own knowledge about their device, and multiple-choice questions in seven basic categories: type of CIED, original indication, functionality, manufacturer, number of active leads, estimated battery life, and number of shocks received. We compared these answers to their interrogation reports to assess accuracy. We also asked participants what they would like to be aware of regarding their CIED. RESULTS: From this cohort, 344 of 400 (86%) (62.9 ± 12.8 years and 64 % males) agreed to take the survey and were included in the analysis. At baseline, 63.2% agreed or strongly agreed that they were knowledgeable about their devices. The overwhelming majority of patients demonstrated CIED knowledge deficits in at least one content area (n = 294, 86%), or more than two content areas (n = 176, 51%). Patients agreed or strongly agreed that they had a desire to have information regarding each of the following: battery life (84%), activity level (79%), heart rate trend (75%), and ventricular arrhythmias (74%). CONCLUSION: There is a large discrepancy in patients' level of knowledge regarding their CIEDs and their wish to know more details. Future technologies should satisfy providers' goals to educate their patients with basic information and fulfill patients' desire to obtain more data from their CIEDs.

Safety of Oral Dofetilide Reloading for Treatment of Atrial Arrhythmias.

BACKGROUND: Although dofetilide labeling states that the drug must be initiated or reinitiated with continuous electrocardiographic monitoring and in the presence of trained personnel, the risks of dofetilide reloading justifying repeat hospitalization have not been investigated. METHODS AND RESULTS: Patients admitted for dofetilide reloading for atrial arrhythmias were retrospectively reviewed. The need for dose adjustment and the incidence of torsades de pointes (TdP) were identified. The incidence of TdP in dofetilide reloading was compared with patients admitted for dofetilide initial loading. Of 138 patients admitted for dofetilide reloading for atrial arrhythmias, 102 were reloaded at a previously tolerated dose, 30 with a higher dose from a previously tolerated dose and 2 at a lower dose; prior dosage was unknown in 4 patients. Dose adjustment or discontinuation was required in 44 patients (31.9%). No TdP occurred in the same dose reloading group, but TdP occurred in 2 patients admitted to increase dofetilide dosage (0% versus 6.7%; P=0.050). Dofetilide dose adjustment or discontinuation was required in 30 of 102 patients (29.4%) reloaded at a previously tolerated dose and in 11 of 30 patients (36.7%) admitted for an increase in dose. CONCLUSIONS: Although no TdP occurred in patients admitted to reload dofetilide at the same dose as previously tolerated, dosage adjustments or discontinuation was frequent and support the need for hospitalization for dofetilide reloading. Patients admitted for reloading with a higher dose tended to be at higher risk for TdP than patients reloaded at a prior tolerated dose.

Cardiac Troponin Measurement in the Critically Ill: Potential for Guiding Clinical Management.

BACKGROUND: Elevated cardiac troponin (cTn) in the absence of acute coronary syndromes (ACS) is associated with increased mortality in critically ill patients. There are no evidence-based interventions that reduce mortality in this group. OBJECTIVES: We performed a retrospective investigation of the Veterans Administration Inpatient Evaluation Center database to determine whether drugs used in ACS (ß-blockers, aspirin, and statins) are associated with reduced mortality in critically ill patients. METHODS: Thirty-day mortality was determined for non-ACS patients admitted to any Veterans Administration Intensive Care Unit between October 1, 2007, and September 30, 2008, adjusted for severity of illness. Troponin assay values were normalized across institutions. RESULTS: Multivariate analyses for 30-day mortality showed an odds ratio (OR) of 1.82 for patients with high cTn (P < 0.0001, cTn > 10% coefficient of variation) and 1.18 for intermediate cTn (P = 0.0021, cTn between lowest limit detectable and 10% coefficient of variation) compared with patients with no elevation, adjusting for severity of illness (n = 19,979). Logistic regression models showed that patients with no or intermediate elevations of cTn taking statins within 24 hours of cTn measurement had a lower mortality than patients not taking statins (OR, 0.66; 95% confidence interval [95% CI], 0.53-0.82; P = 0.0003), whereas patients with high cTn had a lower mortality if they were taking ß-blockers or aspirin within 24 hours of cTn measurement compared to patients not taking ß-blockers or aspirin (ß-blockers: OR, 0.80; 95% CI, 0.68-0.94; P = 0.0077; aspirin: OR, 0.81;95% CI, 0.69-0.96; P = 0.0134). CONCLUSIONS: This retrospective study confirms an association between elevated troponin and outcomes in critically ill patients without ACS and identifies statins, ß-blockers, and aspirin as potential outcome modifiers in a cTn-dependent manner.

Safety of oral dofetilide for rhythm control of atrial fibrillation and atrial flutter.

BACKGROUND: Although dofetilide is widely used in the United States for rhythm control of atrial fibrillation, there is limited postapproval safety data in the atrial fibrillation population despite its known risk of Torsade de pointes (TdP). METHODS AND RESULTS: We conducted a retrospective chart review of a cohort of 1404 patients initially loaded on dofetilide for atrial fibrillation suppression at the Cleveland Clinic from 2008 to 2012 to evaluate the incidence and risk factors for in-hospital adverse events and the long-term safety of continued use. Of the 17 patients with TdP during loading (1.2%), 10 had a cardiac arrest requiring resuscitation (1 death), 5 had syncope/presyncope, and 2 were asymptomatic. Dofetilide loading was stopped for 105 patients (7.5%) because of QTc prolongation or TdP. Variables correlated with TdP were (1) female sex, 2) 500-µg dose, (3) reduced ejection fraction, and (4) increase in QTc from baseline. One-year all-cause mortality was higher in patients who continued dofetilide compared with those who discontinued use (hazard ratio, 2.48; 95% confidence interval, 1.08-5.71; P=0.03). Those patients who had a TdP event had higher one-year all-cause mortality than those who did not (17.6% versus 3% at 1 year; P<0.001). CONCLUSIONS: Dofetilide loading has a low but finite risk of TdP and other adverse events that warrant the current Food and Drug Administration-mandated practice of inpatient monitoring during drug loading. In this cohort, all-cause mortality was higher at 1 year in those patients continued on dofetilide and in those patients who experienced TdP while loading.

Capsule endoscopy in examination of esophagus for lesions after radiofrequency catheter ablation: a potential tool to select patients with increased risk of complications.

BACKGROUND: Esophageal injury can result from left atrial radiofrequency ablation (RFA) therapy, with added concern because of its possible relationship to the development of atrial-esophageal (A-E) fistulas. OBJECTIVE: Evaluate utility of esophageal capsule endoscopy to detect esophageal lesions as a complication of RFA therapy in the treatment of atrial fibrillation (AF). METHODS: Consecutive patients with AF who underwent left atrial RFA therapy and received capsule endoscopy within 48 hours postablation. Video was reviewed by a single gastroenterologist. The medical records were also reviewed for symptoms immediately postablation and at the 3-month follow-up. RESULTS: A total of 93 consecutive patients were included and 88 completed the study and were analyzed. The prevalence of esophageal lesions was 17% (15/88 patients). Nine percent (8/88) of these patients had lesions anatomically consistent with the location of the ablation catheter. Six patients with positive capsule findings had symptoms of chest pain (3/6, 50%), throat pain (2/6, 33%), nausea (1/6, 17%), and abdominal pain (1/6, 17%). An additional 24 patients were symptomatic postablation, but with normal capsule findings. All patients with identified lesions by capsule endoscopy received oral proton pump inhibitor therapy, and were instructed to contact the Cleveland Clinic in the event of worsening symptoms. No delayed complications were reported at the 3-month follow-up. CONCLUSION: This study supports the use of capsule endoscopy as a tool for the detection of esophageal injury post-RFA therapy. PillCam ESO is well tolerated and provides satisfactory images of the areas of interest in the esophagus without potential risk related to insufflation with regular esophagogastroduodenoscopy.

Upper airway volume segmentation analysis using cine MRI findings in children with tracheostomy tubes.

OBJECTIVE: The purpose of this study is to evaluate the airway dynamics of the upper airway as depicted on cine MRI in children with tracheotomy tubes during two states of airflow through the upper airway. MATERIALS AND METHODS: Sagittal fast gradient echo cine MR images of the supra-glottic airway were obtained with a 1.5T MRI scanner on seven children with tracheotomy tubes. Two sets of images were obtained with either the tubes capped or uncapped. The findings of the cine MRI were retrospectively reviewed. Volume segmentation of the cine images to compare the airway volume change over time (mean volume, standard deviation, normalized range, and coefficient of variance) was performed for the capped and uncapped tubes in both the nasopharynx and hypopharynx (Signed Rank Test). RESULTS: Graphical representation of the airway volume over time demonstrates a qualitative increased fluctuation in patients with the tracheotomy tube capped as compared to uncapped in both the nasopharyngeal and hypopharyngeal regions of interest. In the nasopharynx, the mean airway volume (capped 2.72 mL, uncapped 2.09 mL, p = 0.0313), the airway volume standard deviation (capped 0.42 mL, uncapped 0.20 mL, p = 0.0156), and the airway volume range (capped 2.10 mL, uncapped 1.09 mL, p = 0.0156) were significantly larger in the capped group of patients. In the hypopharynx, the airway volume standard deviation (capped 1.54 mL, uncapped 0.67 mL, p = 0.0156), and the airway volume range (capped 6.44 mL, uncapped 2.93 mL, p = 0.0156) were significantly larger in the capped tubes. The coefficient of variance (capped 0.37, uncapped 0.26, p = 0.0469) and the normalized range (capped 1.52, uncapped 1.09, p = 0.0313) were significantly larger in the capped tubes. CONCLUSION: There is a statistically significant change in airway dynamics in children with tracheotomy tubes when breathing via the airway as compared to breathing via the tracheotomy tube.

Comparison of lingual tonsil size as depicted on MR imaging between children with obstructive sleep apnea despite previous tonsillectomy and adenoidectomy and normal controls.

BACKGROUND: Cine MRI has become a useful tool in the evaluation of patients with persistent obstructive sleep apnea (OSA) despite previous surgical intervention and in patients with underlying conditions that render them susceptible to multilevel airway obstruction. Findings on cine MRI studies have also increased our understanding of the mechanisms and anatomic causes of OSA in children. OBJECTIVE: To compare lingual tonsil size between children with OSA and a group of normal controls. In addition, a subanalysis was made of the group of children with OSA comparing lingual tonsils between children with and without underlying Down syndrome. MATERIALS AND METHODS: Children with persistent OSA despite previous palatine tonsillectomy and adenoidectomy and controls without OSA underwent MR imaging with sagittal fast spin echo inversion-recovery images, and lingual tonsils were categorized as nonperceptible at imaging or present and measurable. When present, lingual tonsils were measured in the maximum anterior-posterior diameter. If lingual tonsils were greater than 10 mm in diameter and abutting both the posterior border of the tongue and the posterior pharyngeal wall, they were considered markedly enlarged. RESULTS: There were statistically significant differences between the OSA and control groups for the presence vs. nonvisualization of lingual tonsils (OSA 33% vs. control 0%, P=0.0001) and mean diameter of the lingual tonsils (OSA 9.50 mm vs. control 0.0 mm, P=0.00001). Within the OSA group, there were statistically significant differences between children with and without Down syndrome for the three lingual tonsil width categories (P=0.0070) and occurrence of markedly enlarged lingual tonsils (with Down syndrome 35% vs. without Down syndrome 3%, P=0.0035). CONCLUSIONS: Enlargement of the lingual tonsils is relatively common in children with persistent obstructive sleep apnea after palatine tonsillectomy and adenoidectomy. This is particularly true in patients with Down syndrome.

Obstructive sleep apnea: MR imaging volume segmentation analysis.

PURPOSE: To retrospectively determine airway wall motion with volume segmentation of transverse cine magnetic resonance (MR) images in children with obstructive sleep apnea (OSA). MATERIALS AND METHODS: Transverse fast gradient-echo cine MR images of the hypopharynx were obtained at 1.5 T in 31 children with OSA (eight girls, 23 boys; mean age, 11.3 years) and 21 children free of airway symptoms who underwent MR imaging for other clinical indications (11 girls, 10 boys; mean age, 3.5 years). Volume segmentation with a k-means clustering algorithm was applied to transverse cine MR images to quantify airway volumes at each time. Airway wall motion for each child was described with standard deviation and range. Coefficient of variance and normalized range, which are independent of airway size, were used to compare groups (Kruskal-Wallis test). RESULTS: Plots of airway volume over time demonstrated large fluctuations during respiration in children with OSA and minimal fluctuations in controls; findings were consistent with airway distention and airway collapse in OSA. Average airway transverse volume was larger in the group with OSA than in the control group (OSA group, 2.52 mL; control group, 0.936 mL; P <.001). Mean standard deviation (OSA group, 0.840 mL; control group, 0.17 mL; P <.001) and mean range of airway cross section (OSA group, 3.552 mL; control group, 0.864 mL; P <.001) were larger in the group with OSA. Coefficient of variance (OSA group, 0.32; control group, 0.17; P <.001) and normalized range (OSA group, 1.42; control group, 0.96; P <.001) indicate statistically significant difference in airway dynamics in children with OSA. CONCLUSION: Volume segmentation of transverse cine MR images of the hypopharynx aids in quantification of increased airway wall motion in children with OSA. Transverse MR imaging demonstrates both airway distention and collapse in children with OSA.

Oral contrast agents for CT of abdominal trauma in pediatric patients: a comparison of dilute hypaque and water.

OBJECTIVE: Dilute Hypaque Sodium is generally well accepted as an oral contrast agent for CT of pediatric patients who have experienced recent blunt abdominal trauma. However, Hypaque can cause complications. Using water as a substitute contrast agent eliminates these potential complications. The purpose of our study was to compare the performance of water with that of dilute Hypaque as an oral contrast agent. Our hypothesis was that we would find no significant difference in performance between the two agents in defining anatomic details of the hollow gastrointestinal tract. MATERIALS AND METHODS: We performed a retrospective review of 74 CT scans obtained in infants and children who had received blunt abdominal trauma, scoring the quality of visualization of bowel structures, the presence of non-bowel-related findings, and the confidence level in making each assessment. The date range of the scans reviewed overlapped with the period in which the oral contrast material used for scanning such patients was switched from dilute Hypaque to water. Of the 74 CT scans that we reviewed, 53 were obtained with dilute Hypaque and 21 were obtained with water. The sex distribution between the two groups was compared using a chi-square test, whereas the mean age was compared using a two-sample two-sided Student's t test. A two-sample one-sided Student's t test of equivalence was used to analyze the data. RESULTS: Sex distribution for the two groups of patients was not significantly different (69.81% of the group who received dilute Hypaque were boys; 68.18% of the group who received water were boys). Furthermore, the difference in the mean age for the two groups was not statistically significantly (dilute Hypaque group, 8.86 years; water group, 10.18 years). No statistically significant difference in performance of the contrast agents was found with respect to the detection of intraabdominal abnormality. As an oral contrast material, water performed as well as dilute Hypaque in facilitating visualization of all intraabdominal anatomic structures. CONCLUSION: In defining anatomic details of the hollow gastrointestinal tract, water is as effective as dilute Hypaque as an oral contrast agent for CT in the setting of acute blunt abdominal trauma in pediatric patients.

Trial of metronidazole vs. azithromycin for treatment of cyclosporine-induced gingival overgrowth.

Gingival overgrowth usually characterized by increased cellular growth of gingival fibroblasts appears to be multifactorial. In patients receiving CyA for more than 3 months, the incidence can approach 70% and can be attributed to pharmaceutical immunosuppression. Case reports have reported regression of overgrowth with both metronidazole and azithromycin. The goal of this study was to determine the efficacy of metronidazole and azithromycin in reducing CyA-induced gingival overgrowth. Twenty-five patients were included in this double-blinded randomized study. All patients were receiving CyA as medically indicated and diagnosed with gingival overgrowth by a dentist. Patients were randomized to receive either 5-days of azithromycin or 7-days of metronidazole given at baseline only. The extent of gingival overgrowth was measured at 0, 2, 4, 6, 12, and 24 wk. Fourteen patients at CCF and 11 patients at CCHMC were studied. Repeated measures anova was performed to assess differences within and between groups. Gingival overgrowth at baseline was not statistically different between groups. The mean degree of gingival overgrowth after treatment was different across all time intervals (p = 0.0049) showing azithromycin to be more effective than metronidazole. Therapy with azithromycin offers an effective alternative to the management of CyA-induced gingival overgrowth.

Diagnostic errors by radiology residents in interpreting pediatric radiographs in an emergency setting.

BACKGROUND: There are few data regarding the frequency and type of diagnostic errors made by radiology residents and fellows ("trainees"). However, increasing interest in reducing medical errors highlights the need to analyze which areas of medical knowledge are most problematic for physicians-in-training, including radiology trainees. Once these areas are identified, they can be emphasized during training. OBJECTIVE: To quantify the diagnostic errors made by radiology trainees interpreting radiographs from a pediatric emergency department. MATERIALS AND METHODS: A total of 23,273 dictations of emergency radiographs performed over a 1-year period at a pediatric hospital were analyzed for corrections after staff interpretation and for type and incidence of missed abnormalities by radiology trainees. Errors were categorized by type of pathology and anatomic region. RESULTS: Of the 80 errors detected, 90% were false negatives and 69% were recurrent. Most errors (69%) involved the diagnosis of fractures and/or dislocations. Sixty-one percent of all recurrent errors involved buckle, Salter II, avulsion, and transverse fractures-yet these cases constituted only 3% of all cases seen during the study period. CONCLUSION: The most common errors made by radiology trainees can be identified. By targeting these errors, training programs can improve the quality and relevance of the education they provide.

Incidence and severity of vesicoureteral reflux in children related to age, gender, race and diagnosis.

PURPOSE: We determine if the incidence and grade of vesicoureteral reflux (VUR) differs in children based on age, race and gender, and if the incidence and severity of VUR are related to race in girls younger than 7 years presenting for evaluation after urinary tract infection (UTI). MATERIALS AND METHODS: The records of all children who underwent a voiding cystourethrogram or radionuclide cystogram between 1993 and 2001 were retrospectively reviewed. Age, gender, race, clinical indication and highest grade of VUR were recorded for the first voiding cystourethrogram or radionuclide cystogram. Frequency tables and logistic regression were conducted to correlate demographics to incidence and severity of VUR. RESULTS: A total of 15,504 patients were included in the analysis. Overall, black children were a third as likely as white children (p <0.0001) and females were twice as likely as males (p <0.0001) to have VUR. Compared to children 0 to 2 years old, the occurrence of reflux was 0.5 times as likely in those 3 to 6 years old (p <0.0001), 0.3 times as likely in those 7 to 11 years old (p <0.0001) and 0.15 times as likely in those 12 to 21 years old (p <0.0001). When analyzing children with UTI, results were similar. Of the patients with VUR 65% were younger than 7 years. The incidence of VUR in black girls younger than 7 years with a diagnosis of UTI was less than 10% compared to white girls, and no black girl had high grade reflux. In young children referred for UTI the incidence and severity of VUR in black patients were significantly lower than those of white girls. CONCLUSIONS: This study validates previous observations regarding the low incidence of VUR in black children.

Using a phantom to compare MR techniques for determining the ratio of intraabdominal to subcutaneous adipose tissue.

OBJECTIVE: Patients who have a greater distribution of intraabdominal adipose tissue as compared with subcutaneous adipose tissue and an increased ratio of intraabdominal adipose tissue to subcutaneous adipose tissue are at greater risk for developing cardiovascular disease and type 2 diabetes mellitus. In previous MR investigations, researchers have used conventional T1-weighted spin-echo images to determine the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue. However, no investigation, to our knowledge, has been performed to determine the accuracy of using different MR sequences to estimate adipose distribution. The purpose of our investigation was to compare MR imaging and segmentation techniques in calculating the ratio of intraabdominal to subcutaneous adipose tissue using an adiposity phantom. MATERIALS AND METHODS: A phantom was created to simulate the distribution of subcutaneous and intraabdominal fat (with known volumes). Axial MR images were obtained twice through the phantom using a 5-mm slice thickness and zero gap for the following T1-weighted sequences: spin-echo, fast Dixon, and three-dimensional (3D) spoiled gradient-echo. An in-house computer software program was then used to segment the volumes of fat and calculate the volume of intraabdominal adipose tissue and subcutaneous adipose tissue and the ratio of intraabdominal to subcutaneous adipose tissue. Each imaging data set was segmented three times, so six sets of data were yielded for each imaging technique. The percentage predicted of the true volume was calculated for each MR imaging technique for each fat variable. The mean percentages for each variable were then compared using one-factor analysis of variance to determine whether differences exist among the three MR techniques. RESULTS: The three MR imaging techniques had statistically significant different means for the predicted true volume of two variables: volume of subcutaneous adipose tissue (p < 0.001) and volume of intraabdominal adipose tissue (p = 0.0426). Estimates based on fast Dixon images were closest to the true volumes for all the variables. All MR imaging techniques performed similarly in estimating the ratio of intraabdominal adipose tissue to subcutaneous adipose tissue (p = 0.9117). The acquisition time for the 3D spoiled gradient-echo images was 10-22 times faster than for the other sequences. CONCLUSION: Conventional T1-weighted spin-echo MR imaging, the current sequence used in practice for measuring visceral adiposity, may not be the optimal MR sequence for this purpose. We found that the T1-weighted fast Dixon sequence was the most accurate at estimating all fat volumes. The T1-weighted 3D spoiled gradient-echo sequence generated similar ratios of intraabdominal to subcutaneous adipose tissue in a fraction of the acquisition time.

Upper airway motion depicted at cine MR imaging performed during sleep: comparison between young Patients with and those without obstructive sleep apnea.

PURPOSE: To compare the patterns of dynamic airway motion depicted on cine magnetic resonance (MR) images obtained during sleep between young patients with and those without obstructive sleep apnea (OSA). MATERIALS AND METHODS: Fast gradient-echo sequences were performed in the sagittal midline by using a 1.5-T unit to create cine MR images. Cine MR images obtained during sleep in 16 young patients with OSA were compared with those obtained in 16 young patients with no airway symptoms of airway disease. The nasopharynx, oropharynx, and hypopharynx were characterized in terms of airway motion as static patent (SP), dynamic patent, intermittent collapsed (IC), or static collapsed (SC); and the maximal diameter and greatest change in diameter (in millimeters) of these airways were calculated. Adenoid tonsil size and mouth position (ie, opened or closed) were determined. Differences in the frequency of MR imaging parameters in the different anatomic regions were evaluated by using Fisher exact, chi 2, and sample t tests. RESULTS: There were statistically significant differences in the following parameters between the two groups: nasopharynx SP (P <.001) and IC (P <.001); hypopharynx SP (P <.001) and IC (P <.001); and mean change in airway diameter of the nasopharynx (P <.001) and hypopharynx (P <.001). The mean adenoid tonsil size in the patients with OSA was larger (P =.006). CONCLUSION: There are significant differences in the patterns of dynamic airway motion between young patients with and those without OSA.

In-plane bismuth breast shields for pediatric CT: effects on radiation dose and image quality using experimental and clinical data.

OBJECTIVE: The purpose of our study was to evaluate the amount of radiation dose reduction and its effect on image quality when using an in-plane bismuth breast shield for multidetector CT (MDCT) of the chest and abdomen in female pediatric patients. SUBJECTS AND METHODS: Fifty consecutive MDCT examinations (chest, 29; abdomen, 21) of female pediatric patients (mean age, 9 years; range, 2 months-18 years) were performed with a 2-ply (1.7 g of bismuth per square centimeter) bismuth shield (three sizes to accommodate patients of varying sizes) overlying the patient's breasts. MDCT images were evaluated for a perceptible difference in image quality in the lungs at the anatomic level under the shield as compared with nonshielded lung and whether the images were of diagnostic quality. In addition, 2-mm regions of interest were placed in the peripheral anterior and posterior portions of each lung in shielded and nonshielded areas, and noise (standard deviation in Hounsfield units) was measured in the regions. Differences among the regions in noise were compared for shielded versus nonshielded areas (paired t test). To measure differences in actual dose, we also evaluated the breast shield with an infant anthropomorphic phantom using thermoluminescent detectors in the breast tissue. The phantom was imaged with and without the breast shield using identical MDCT parameters. RESULTS: All MDCT scans of patients were of diagnostic quality with no perceptible difference in image quality in shielded versus nonshielded lung. We found no statistically significant difference in noise between the shielded and nonshielded lung regions of interest (shielded: mean noise, 17.3 H; nonshielded: mean noise, 18.8 H; p = 0.5180). Phantom measurements revealed a 29% reduction in radiation dose to the breast when a medium-dose MDCT protocol was used. CONCLUSION: Bismuth in-plane breast shielding for pediatric MDCT decreased radiation dose to the breast without qualitative or quantitative changes in image quality.

Low-tube-current multidetector CT for children with suspected extrinsic airway compression.

OBJECTIVE: The purpose of our study was to review the technical success achieved using low-tube-current multidetector CT for the evaluation of children with suspected extrinsic airway compression and to evaluate the need for sedation during this procedure. MATERIALS AND METHODS: We reviewed all CT examinations performed for the evaluation of extrinsic airway compression during the first year after installation of a multidetector CT scanner at a pediatric hospital. We recorded the technical parameters including tube current, kilovoltage, slice thickness, mode of study, sedation technique, and amount of contrast material and noted which postprocessing techniques were applied. Studies were evaluated for timing of contrast bolus, image quality, motion artifact, need for sedation, and the diagnoses made. RESULTS: Fifty-four studies were performed in 50 patients (30 boys, 20 girls; age range, 15 days to 17 years; mean age, 2.4 years). The mean tube current was 52.2 mA (range, 30-140 mA). Thirty-four studies (63%) were performed without sedation: 12 with sedation administered under supervision of the radiologist, six with general anesthesia supervised by an anesthesiologist, and two in patients who arrived in the radiology department already intubated. Imaging quality was excellent in 35 studies (65%), diagnostic in 19 studies (35%), and poor in none. Motion artifact was present on several slices in two examinations (4%). Contrast medium administration was well-timed in 49 studies (91%), early in three studies (5%), and late in two studies (4%). Airway abnormalities were detected in 26 (48%) of the studies and included extrinsic compression by vascular anomalies (n = 14) or nonvascular masses (n = 5) and intrinsic airway disease without extrinsic compression (n = 7). CONCLUSION: Evaluation for extrinsic compression of the airway in children can be accomplished using a low-tube-current multidetector CT protocol; in most pediatric patients, the examination can be performed without sedation.

Venous pressure monitoring does not accurately predict access failure in children.

Access failure is a significant cause of morbidity and mortality in hemodialysis patients. Routine monitoring of arteriovenous (AV) fistulas and grafts could increase access longevity. Dynamic venous pressure monitoring is a surveillance test advocated to detect early signs of vascular thrombosis. Venous pressure measurements obtained, per DOQI recommendations, in children undergoing hemodialysis with an AV fistula or graft were reviewed. Baseline venous pressures were established by calculating the mean of venous pressures obtained without an antecedent thrombosis. A paired t-test was performed comparing mean baseline pressure measurements with pressures immediately preceding each thrombosis episode. Since some patients had multiple thrombosis episodes, the assumption of independence was not met. A second paired t-test was performed comparing mean baseline pressures with the mean pressure measurement per individual, obtained immediately preceding a thrombosis episode; 335 venous pressures were collected in ten pediatric patients. Eighteen thromboses occurred in five patients, in whom a total of 241 venous pressures were measured. Venous pressures did not correlate with thrombotic events ( P=0.4284). Specific thrombotic events for each patient were correlated with mean patient-specific venous pressures and showed no correlation ( P=0.3229). Dynamic venous pressure monitoring is not an adequate predictor of access thrombosis in pediatric patients.