Expenditure mapping of pediatric imaging costs using a resource utilization band analysis of claims data.

OBJECTIVE: To segregate imaging expenditures from claims data by resource utilization bands (RUBs) and underlying conditions to create an "expenditure map" of pediatric imaging costs. METHODS: A Claims data for children enrolled in a commercial value-based plan were categorized by RUB 0 non-user, 1 healthy user, 2 low morbidity, 3 moderate morbidity, 4 high morbidity, & 5 very high morbidity. The per member per year (PMPY) expense, total imaging spend, and imaging modality with the highest spend were assessed for each RUB. Diagnosis categories associated with high imaging costs were also evaluated. RESULTS: There were 40,022 pediatric plan members. 14% had imaging-related claims accounting for approximately $2.8 million in expenditures. Member distribution and mean PMPY expenditure RUB was respectively: RUB 0 (3,037, $0), RUB 1 (6,604, $7), RUB 2 - 13,698, $27), RUB 3 - 13,341, $87), RUB 4 (2,810, $268), RUB 5 (532, $841). RUB 3 had the largest total imaging costs at $1,159,523. The imaging modality with the greatest mean PMPY expense varied by RUB with radiography highest in lower RUBs and MRI highest in higher RUBs. The top 3 diagnoses associated with the highest total imaging costs were developmental disorders ($443,980), asthma ($388,797), and congenital heart disease ($294,977) and greatest mean PMPY imaging expenditures malignancy/leukemia ($3,100), transplant ($2,639), and tracheostomy ($1,661). DISCUSSION: Expense mapping using claims data allows for a better understanding of the distribution of imaging costs across a covered pediatric population. This tool may assist organizations in planning effective cost-reduction initiatives and learning how imaging utilization varies by patient complexity in their system.

The American Board of Radiology B. Leonard Holman Research Pathway to Initial Certification: Opportunities Lost for Diagnostic Radiology.

OBJECTIVE: In 1998, the American Board of Radiology introduced the B. Leonard Holman Research Pathway (HRP) to initial certification for trainees in diagnostic radiology (DR) and radiation oncology (RO) motivated to pursue research-oriented careers in academic DR and RO. CONCLUSION: The HRP Committee anticipated that there would be a relatively even distribution between DR and RO participants, but with 18 years of experience that has not been the case. This article focuses on the HRP and DR.

Practical Application of the International Neuroblastoma Risk Group Staging System: A Pictorial Review.

Because of issues with the previous staging system, the International Neuroblastoma Risk Group Staging System (INRG-SS) was created in 2009. The INRG-SS is based on preoperative imaging, rather than surgical, staging and emphasizes Imaging-Defined Risk Factors as the determining factors between L1 and L2 stages. Like with the introduction of any new tool, based on the authors' experience, there has been a time-lag related to adoption of the INRG-SS staging system by radiologists. This pictorial essay offers a practical approach to learning and utilizing the INRG system, emphasizing use of the descriptive terms which determine the presence or absence of imaging-defined risk factors.

Magnetic resonance imaging of obstructive sleep apnea in children.

Sleep-disordered breathing has a spectrum of severity that spans from snoring and partial airway collapse with increased upper airway resistance, to complete upper airway obstruction with obstructive sleep apnea during sleeping. While snoring occurs in up to 20% of children, obstructive sleep apnea affects approximately 1-5% of children. The obstruction that occurs in obstructive sleep apnea is the result of the airway collapsing during sleep, which causes arousal and impairs restful sleep. Adenotonsillectomy is the first-line treatment of obstructive sleep apnea and is usually effective in otherwise healthy nonsyndromic children. However, there are subgroups in which this surgery is less effective. These subgroups include children with obesity, severe obstructive sleep apnea preoperatively, Down syndrome, craniofacial anomalies and polycystic ovarian disease. Continuous positive airway pressure (CPAP) is the first-line therapy for persistent obstructive sleep apnea despite previous adenotonsillectomy, but it is often poorly tolerated by children. When CPAP is not tolerated or preferred by the family, surgical options beyond adenotonsillectomy are discussed with the parent and child. Dynamic MRI of the airway provides a means to identify and localize the site or sites of obstruction for these children. In this review the authors address clinical indications for imaging, ideal team members to involve in an effective multidisciplinary program, basic anesthesia requirements, MRI protocol techniques and interpretation of the findings on MRI that help guide surgery.

Radiographic appearance and clinical significance of fidget spinner ingestions.

BACKGROUND: According to anecdotal press reports, there have been medically significant ingestions of fidget spinner toys, including ingestions that required endoscopic intervention. Fidget spinners have been marketed to improve attention and have been suggested as a therapeutic alternative to medications in children with attention deficit hyperactivity disorder (ADHD). OBJECTIVE: To describe the radiographic appearance and features of ingested fidget spinner components. To evaluate clinical significance via rates of endoscopic intervention, incidence in patients on ADHD medications, and mean age compared to other accidental foreign body ingestions. MATERIALS AND METHODS: A nested retrospective case control study analyzed pediatric accidental foreign body ingestions identified via electronic medical record search between March 1, 2017, and Feb. 28, 2018. Radiographic identifiability, component type and maximum diameter of ingested fidget spinner components were described. A nested cohort of non-fidget spinner ingestions between May 1 and Aug. 31, 2017, was compared with the fidget spinner ingestions for rates of endoscopic intervention (a), concomitant use of ADHD medication (b) and mean age (c) using the Fisher exact test (a and b) and independent samples t-test (c). RESULTS: There were 1,095 unintentional foreign body ingestions. Ten were ingested fidget spinner component ingestions. Eight of the 10 ingested components were radiographically identifiable. Compared with the nested cohort of non-fidget spinner ingestions, fidget spinner ingestions were more likely to undergo endoscopic intervention (P=0.009, 5/10 fidget spinner ingestions vs. 54/383 other ingestions). Fidget spinner patients were more likely to be on ADHD medication (P=0.011, 2/10 fidget spinners vs. 5/383 other). Fidget spinner mean patient age was significantly older than other ingestions (P=0.015, mean: 7.1 years fidget spinner ingestions vs. 4.0 years for other ingestions). CONCLUSION: Compared with other foreign body ingestions, patients who ingested fidget spinner components were more likely to undergo endoscopic intervention, had a higher rate of ADHD medication use and were older. Familiarity with the radiographic appearance of ingested fidget spinner components is important for patient management.

Key Concepts of Patient Safety in Radiology.

Harm from medical error is a difficult challenge in health care, including radiology. Modern approaches to patient safety have shifted from a focus on individual performance and reaction to errors to development of robust systems and processes that create safety in organizations. Organizations that operate safely in high-risk environments have been termed high-reliability organizations. Such organizations tend to see themselves as being constantly bombarded by errors. Thus, the goal is not to eliminate human error but to develop strategies to prevent, identify, and mitigate errors and their effects before they result in harm. High-level reliability strategies focus on systems and organizational culture; intermediate-level reliability strategies focus on establishment of effective processes; low-level reliability strategies focus on individual performance. Although several classification schemes for human error exist, modern safety researchers caution against overreliance on error investigations to improve safety. Blaming individuals involved in adverse events when they had no intent to cause harm has been shown to undermine organizational safety. Safety researchers have coined the term just culture for the successful balance of individual accountability with accommodation for human fallibility and system deficiencies. Safety is inextricably intertwined with an organization's quality efforts. A quality management system that focuses on standardization, making errors visible, building in quality, and constantly stopping to fix problems results in a safer environment and engages personnel in a way that contributes to a culture of safety.

Radiation dose metrics in CT: assessing dose using the National Quality Forum CT patient safety measure.

PURPOSE: The National Quality Forum (NQF) is a nonprofit consensus organization that recently endorsed a measure focused on CT radiation doses. To comply, facilities must summarize the doses from consecutive scans within age and anatomic area strata and report the data in the medical record. Our purpose was to assess the time needed to assemble the data and to demonstrate how review of such data permits a facility to understand doses. METHODS AND MATERIALS: To assemble the data we used for analysis, we used the dose monitoring software eXposure to automatically export dose metrics from consecutive scans in 2010 and 2012. For a subset of 50 exams, we also collected dose metrics manually, copying data directly from the PACS into an excel spreadsheet. RESULTS: Manual data collection for 50 scans required 2 hours and 15 minutes. eXposure compiled the data in under an hour. All dose metrics demonstrated a 30% to 50% reduction between 2010 and 2012. There was also a significant decline and a reduction in the variability of the doses over time. CONCLUSION: The NQF measure facilitates an institution's capacity to assess the doses they are using for CT as part of routine practice. The necessary data can be collected within a reasonable amount of time either with automatic software or manually. The collection and review of these data will allow facilities to compare their radiation dose distributions with national distributions and allow assessment of temporal trends in the doses they are using.

Quality improvement initiative to reduce serious safety events and improve patient safety culture.

BACKGROUND AND OBJECTIVE: Many thousands of patients die every year in the United States as a result of serious and largely preventable safety events or medical errors. Safety events are common in hospitalized children. We conducted a quality improvement initiative to implement cultural and system changes with the goal of reducing serious safety events (SSEs) by 80% within 4 years at our large, urban pediatric hospital. METHODS: A multidisciplinary SSE reduction team reviewed the safety literature, examined recent SSEs, interviewed internal leaders, and visited other leading organizations. Senior hospital leaders provided oversight, monitored progress, and helped to overcome barriers. Interventions focused on: (1) error prevention; (2) restructuring patient safety governance; (3) a new root cause analysis process and a common cause database; (4) a highly visible lessons learned program; and (5) specific tactical interventions for high-risk areas. Our outcome measures were the rate of SSEs and the change in patient safety culture. RESULTS: SSEs per 10000 adjusted patient-days decreased from a mean of 0.9 at baseline to 0.3 (P < .0001). The days between SSEs increased from a mean of 19.4 at baseline to 55.2 (P < .0001). After a worsening of patient safety culture outcomes in the first year of intervention, significant improvements were observed between 2007 and 2009. CONCLUSIONS: Our multifaceted approach was associated with a significant and sustained reduction of SSEs and improvements in patient safety culture. Multisite studies are needed to better understand contextual factors and the significance of specific interventions.

Improving patient safety in radiology.

OBJECTIVE: Both horizontally oriented interventions (aimed at improving culture and environment in an effort to reduce the number of human errors potentially leading to patient harm) and vertically oriented (aimed at a specific area of errors) are needed to create a comprehensive safety program in radiology. Our objective is to describe horizontal interventions introduced to improve safety in radiology. CONCLUSION: Horizontal interventions--such as operational rounds with radiology leadership, safety coach programs, error prevention training, and a lessons-learned communication program--can successfully improve the safety culture and performance in radiology.

Findings on MR sleep studies as biomarkers to predict outcome of genioglossus advancement in the treatment of obstructive sleep apnea in children and young adults.

OBJECTIVE: Genioglossus advancement, an operation to pull the tongue anteriorly, is a treatment of obstructive sleep apnea (OSA) secondary to glossoptosis. MRI predictors to identify which children will benefit from genioglossus advancement would be helpful for planning. We reviewed imaging findings on MR sleep studies as biomarkers to predict success or failure of genioglossus advancement in the treatment of OSA in children and young adults. MATERIALS AND METHODS: Twenty-eight patients who had undergone genioglossus advancement and preoperative MRI were identified. For each subject, genioglossus advancement, which was performed to treat OSA, was categorized as a success or failure on the basis of polysomnography and clinical criteria. Static and dynamic cine MR sequences were retrospectively evaluated for multiple parameters including measurements of the size of the tongue and of the bony confines of the supraglottic airway, the ratio of tongue size to bony confines size, static size and dynamic changes of the retroglossal airway, tonsil size, and soft palate thickness. Radiologists were blinded to the outcome of genioglossus advancement (i.e., success or failure category). Numeric biomarkers were compared in an analysis-of-covariance model adjusting for patient age. RESULTS: Genioglossus advancement was successful for the treatment of OSA in 17 patients and failed in 11 patients. The relative size of the tongue (tongue-bony confines ratio) was larger in patients with a successful surgical outcome than in those for whom the procedure failed (mean ratio, 0.51 vs 0.46; p = 0.023). Smaller adenoids were associated with a successful outcome (mean size of adenoids, 9.1 vs 12.4 mm; p = 0.049). No other biomarker-including absolute tongue size and airway size or dynamic airway motion-was significant. CONCLUSION: The relative (not absolute) tongue size and small size of the adenoid tonsils on MRI were predictors of success of genioglossus advancement for the treatment of glossoptosis causing OSA. These findings may be helpful in guiding surgical decision making in children with OSA.

Improving patient safety in radiology: concepts for a comprehensive patient safety program.

A comprehensive safety program can have a positive influence on safety performance and safety culture within a department of radiology. The program should include both vertical interventions aimed at specific areas of potential safety errors as well as horizontal interventions aimed at improving safety culture and decreasing the baseline rate of human error. In our opinion, the key cultural transformations that must occur to improve safety culture include recognition that safety is an issue, emphasis that everyone is accountable for patient safety, and creating a culture where people are expected and encouraged to speak up in the face of uncertainty. The article describes the horizontal interventions to improve patient safety used in our department.

Magnetic resonance sleep studies in the evaluation of children with obstructive sleep apnea.

Magnetic resonance (MR) sleep studies have been shown to be a useful tool in the evaluation and surgical planning of children with persistent obstructive sleep apnea. MR sleep studies include sequences to evaluate both static anatomic and well as dynamic motion information about the airway. The combination of the information about anatomic abnormalties and patterns of collapse can help in surgical decision making. The most common identified entities include recurrent enlargement of the adenoid tonsils, enlargement of the lingual tonsils, abnormal soft palate, glossoptosis, and hypopharyngeal collapse. This review discusses multiple aspects of MR sleep studies including indications, patient preparation, MR protocols, and commonly made diagnoses.

CT predictors for differentiating benign and clinically worrisome pneumatosis intestinalis in children beyond the neonatal period.

PURPOSE: To determine whether computed tomographic (CT) findings can help differentiate between benign and clinically worrisome causes of pneumatosis intestinalis (PI) in children. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board, and requirement for informed consent was waived. Data were stored in a secured and HIPAA-compliant fashion. CT reports from an 8-year period (July 2000-July 2008) were reviewed to determine all cases with a diagnosis of PI. In these cases, demographic information, clinical presentation, underlying medical condition, and CT findings were reviewed. The cases were grouped into one of two final diagnostic groups: clinically worrisome versus benign PI (diagnosis of exclusion, resolution documented at serial imaging without therapeutic intervention). In each case, the CT findings reviewed included distribution (small bowel, large bowel), extent (mild, moderate, extensive), and morphologic characteristics (linear, cystic, both) of the PI and associated findings such as soft-tissue bowel wall thickening, periintestinal soft-tissue stranding, free air, free fluid, portal venous gas, small-bowel obstruction, and bowel dilatation. Associations between CT findings and benign or clinically worrisome PI were assessed with logistic regression models. RESULTS: There were 44 cases identified. Final diagnostic categories for PI included benign (n = 15) and associated underlying bowel disease (n = 29; definitive in 26 and suspected but not defined in three). The following findings were significant (expressed as percentage of clinically worrisome PI vs percentage of benign): soft-tissue bowel wall thickening (51.2% vs 13.3%, P = .0167), free peritoneal fluid (82.8% vs 33.3%, P = .002), extent of PI (extensive 17.2% vs 69%, P < .001), and periintestinal soft-tissue stranding (55.2% vs 20.0%, P = .0228). Distribution, free peritoneal air, and characteristic morphology (linear vs cystic) were not associated with clinically worrisome PI (all P > .05). CONCLUSION: The cystic or linear pattern of pneumatosis in children is not a useful CT sign to differentiate benign from clinically worrisome PI. CT findings that include soft-tissue thickening of the bowel wall, free fluid, periintestinal soft-tissue stranding, and the extent of PI can be useful in differentiating these entities.

Improving patient safety: effects of a safety program on performance and culture in a department of radiology.

OBJECTIVE: Emphasis is being placed on improving the safety performance of the health care delivery system. The purpose of this study was to evaluate the effects of a program on safety performance and culture in a pediatric radiology department. MATERIALS AND METHODS: A comprehensive safety program implemented in a department of radiology included error prevention training for all employees, a safety coach program, safety awards, Crucial Conversations training, and operational rounds with radiology leaders. The number of serious safety events (events with deviation from best practice, patient harm, and causation) that in part involved radiology were compared for 2 years after implementation of the program and the previous 2 years (baseline). A U.S. Agency for Healthcare Research and Quality safety culture survey was distributed to radiology employees, and the responses were compared for periods early in the program and after full implementation of the program. Fisher's exact test was used to evaluate for statistically significant differences (p < 0.05) in the survey responses and the frequency of serious safety events. RESULTS: Before introduction of the safety program, radiology contributed to a serious safety event an average of once every 200 days as opposed to once in 780 days after implementation of the program (one event in more than two academic years) (p = 0.37). Improvement was found in all 12 dimensions of the culture survey after implementation of the program. Radiology scored higher than hospital averages in 10 of 12 dimensions of the survey. CONCLUSION: The safety program had a positive effect on safety culture. Although it is early in the process and proving statistical significance for rare events such as serious safety events is difficult, the mean number of days between serious safety events has increased from 200 to 780. We conclude that the program is having a positive effect on safety performance.

Prenatal MRI findings of fetuses with congenital high airway obstruction sequence.

OBJECTIVE: To define the MRI findings of congenital high airway obstruction sequence (CHAOS) in a series of fetuses. MATERIALS AND METHODS: Prenatal fetal MR images were reviewed in seven fetuses with CHAOS at 21 to 27 weeks of gestation. The MRI findings were reviewed. The MRI parameters evaluated included the appearance of the lungs and diaphragm, presence or absence of hydrops, amount of amniotic fluid, airway appearance, predicted level of airway obstruction, and any additional findings or suspected genetic syndromes. RESULTS: All the fetuses viewed (7 of 7) demonstrated the following MRI findings: dilated airway below the level of obstruction, increased lung signal, markedly increased lung volumes with flattened or inverted hemidiaphragms, massive ascites, centrally positioned and compressed heart, as well as placentomegaly. Other frequent findings were anasarca (6 of 7) and polyhydramnios (3 of 7). MRI identified the level of obstruction as laryngeal in five cases and tracheal in two cases. In four of the patients, surgery or autopsy confirmed the MRI predicted level of obstruction. Associated abnormalities were found in 4 of 7 (genetic syndromes in 2). Postnatal radiography (n = 3) showed markedly hyperinflated lungs with inverted or flattened hemidiaphragms, strandy perihilar opacities, pneumothoraces and tracheotomy. Two fetuses were terminated and one fetus demised in utero. Four fetuses were delivered via ex utero intrapartum treatment procedure. CONCLUSION: MRI shows a consistent pattern of abnormalities in fetuses with CHAOS, accurately identifies the level of airway obstruction, and helps differentiate from other lung abnormalities such as bilateral congenital pulmonary airway malformation by demonstrating an abnormally dilated airway distal to the obstruction.

CT findings in children with Meckel diverticulum.

BACKGROUND: Approximately 0.04% of the general population will present with a complication related to Meckel diverticulum. The classic teaching is that symptomatic children with Meckel diverticulum present with painless rectal bleeding and are evaluated with a radionuclide scan. Our subjective experience is that we see children with Meckel diverticulum who present with abdominal pain and are evaluated by CT. OBJECTIVE: We reviewed the findings on CT in children with pathologically proven Meckel diverticulum to identify characteristic patterns of presentation. MATERIALS AND METHODS: Databases were searched (2004-2008) for all children who had a pathologic diagnosis of Meckel diverticulum and a CT scan performed prior to surgery. Demographics, pathology, and CT features were reviewed. CT features reviewed included: soft-tissue stranding, abnormal calcifications, bowel obstruction, free air, free peritoneal fluid, cystic mass, intussusception, obvious lead point, location, and whether a normal appendix was identified. The frequency of Meckel diverticulum encountered on CT scans was compared to that found during the same period of time on technetium pertechnetate studies. RESULTS: The review identified 16 subjects (mean age 9.5 years, M:F 9:7). CT findings included: soft-tissue stranding in nine (56%), small-bowel obstruction (SBO) in nine (56%), intussusception in three (19%), free fluid in ten (63%), cystic mass in four (25%), calcification in none (0%), free air in one (6%), and no abnormalities in two (13%). A normal appendix was identified in only five children (31%). There were three basic patterns of presentation of abnormalities: SBO only in five, intussusception with SBO in three, or cystic mass with inflammatory stranding in four (one with SBO). Also, 2.3 times more Meckel diverticulum was encountered on CT than on technetium pertechnetate studies. CONCLUSION: Meckel diverticulum is currently more commonly encountered in children on CT performed for abdominal pain than on technetium pertechnetate studies. There are three categories of appearance on CT: SBO only, intussusception, or a cystic inflammatory mass.

Postoperative pelvic MRI of anorectal malformations.

OBJECTIVE: Patients operated on for anorectal malformations can experience technical complications related to the initial corrective surgery. Many of these complications may necessitate reoperation. Pelvic MRI is part of the evaluation to assess the position of the pulled-through bowel, the sphincter muscles, and the critical area of the posterior urethra. This article reviews the various pelvic MRI findings in these patients. CONCLUSION: Pelvic MRI is a valuable tool in the assessment of postoperative anorectal malformations that may necessitate additional surgery.

The frequency of lingual tonsil enlargement in obese children.

OBJECTIVE: Enlargement of the lingual tonsils is being increasingly recognized as a not uncommon and treatable cause of obstructive sleep apnea, particularly in patients with Down syndrome who have undergone palatine tonsillectomy and adenoidectomy. We have recognized an increasing number of patients who are obese and have obstructive sleep apnea with enlarged lingual tonsils. The purpose of this study was to evaluate the frequency of enlarged lingual tonsils in obese children. SUBJECTS AND METHODS: Seventy-one obese children (mean body mass index = 41.6 kg/m(2)) underwent sagittal fast spin-echo inversion recovery imaging. Lingual tonsils were identified and measured in the greatest anteroposterior diameter. Lingual tonsils > 10 mm were considered markedly enlarged. The subgroup with absent palatine tonsils (previous tonsillectomy) (n = 41) were compared with those with palatine tonsils present (n = 30). RESULTS: Forty-four (62%) of the obese children had measurable lingual tonsils, which is greater than the frequency previously reported in normal subjects (0%), subjects with obstructive sleep apnea (33%), or subjects with Down syndrome and obstructive sleep apnea (50%). Ten (14%) had lingual tonsils > 10 mm. Obese subjects with absent palatine tonsils (previous tonsillectomy) had a higher prevalence of measurable lingual tonsils than those with palatine tonsils (78% vs 22%, respectively; p < 0.001) and a higher prevalence of lingual tonsils > 10 mm (90% vs 10%, p < 0.001). CONCLUSION: Obese children have a high frequency of enlargement of the lingual tonsils with a significantly higher prevalence in those with previous tonsillectomy. Enlarged lingual tonsils may play a role in the pathogenesis of obstructive sleep apnea in obese children.

Computational modeling of upper airway before and after adenotonsillectomy for obstructive sleep apnea.

Adenotonsillectomy, the first-line surgical treatment for obstructive sleep apnea (OSA) in children, is successful in only 50% of obese children. Computational fluid dynamics tools, which have been applied to differentiate OSA patients from those without OSA based on the airway flow characteristics, can be potentially used to identify patients likely to benefit from surgical intervention. We present computational modeling of the upper airway before and after adenotonsillectomy in an obese female adolescent with OSA. The subject underwent upper airway imaging on a 1.5 Tesla magnetic resonance imaging (MRI) scanner, and three-dimensional airway models were constructed using airway boundary coordinates from cross-sectional MRI scans. Our results using computational simulations indicate that, in an obese child, the resolution of OSA after adenotonsillectomy is associated with changes in flow characteristics that result in decreased pressure differentials across the airway walls and thus lower compressive forces that predispose to airway collapse. Application of such findings to an obese child seeking surgical treatment for OSA can potentially lead to selection of the surgical procedure most likely to result in OSA resolution. Effective intervention for OSA in this high-risk group will result in reduction in morbidity and the public health concerns associated with OSA.

CT findings for blebs and bullae in children with spontaneous pneumothorax and comparison with findings in normal age-matched controls.

BACKGROUND: Spontaneous pneumothorax (SPTX) is a relatively common condition. In patients with SPTX, CT has been advocated to identify blebs and bullae (BB) to help in management planning. PURPOSE: The study was designed to assess our experience with CT evaluation for underlying BB in children with SPTX as compared to normal controls. MATERIALS AND METHODS: Forty-three children (mean age 16 years, range 13-19 years) with 50 SPTX events with both chest radiographs and CT scans were reviewed. CT findings were compared with those seen in 29 age- and gender-matched controls without SPTX. The parameters evaluated included size, number, location, and ipsi-/contralateral BB; apical lines; and surgical correlation. RESULTS: In the study group, BB were identified in 14 imaged events (28%) (size 2.5-45 mm, one to six BB) with contralateral BB in 11 of the 14 (78.6%). All BB were confined to the apices. BB were sometimes difficult to differentiate from "apical lines"--a suspected normal variant seen in 28 imaged events (56%). Of blebs seen at surgery, 59% were identified on CT, and there were no false-positive CT findings. In the control group, no BB were identified but "apical lines" were seen in eight children (28%). CONCLUSION: BB were seen by CT in 28% of imaged events in children with SPTX and were always confined to the apices. When present, BB were commonly bilateral (78.6%). BB should not be confused with "apical lines," which were not only seen in 56% of imaged events in the SPTX group but also in 28% of the normal controls.