Charles M. Maxfield

CT with a Computer-Simulated Dose Reduction Technique for Detection of Pediatric Nephroureterolithiasis: Comparison of Standard and Reduced Radiation Doses

OBJECTIVE The purpose of this study was to compare the diagnostic capabilities of standard- and reduced-dose CT in the detection of nephroureterolithiasis in children. MATERIALS AND METHODS Forty-five patients 20 years old or younger divided into two groups weighing 50 kg or less and more than 50 kg underwent unenhanced 16-MDCT in the evaluation of acute flank pain. An investigational computer-simulated tube current reduction tool was used to produce additional 80- and 40-mA examination sets (total number of image sets=135). Three independent blinded readers ranked random images for stones (confidence scale, 1-5, least to most), hydronephrosis, noise-based image quality, and presence of nonrenal lesions. RESULTS Compared with the standard tube current used for the original CT scans, there was no significant reduction (p=0.37) in detection of renal stones at the 80-mA setting (mean dose reduction, 67%; range, 43-81%); and at the 40-mA setting (mean dose reduction, 82%; range, 72-90%), the detection rate was significantly lower (p=0.05). At the 40-mA setting, there was no significant difference among the children weighing 50 kg or less (p=0.4). Detection of ureteral stones and hydronephrosis was not significantly different at 80 and 40 mA; however, disease frequency was low, and no definite conclusion can be made. CONCLUSION Simulated dose reduction is a useful tool for determining diagnostic thresholds for MDCT detection of renal stones in children. Use of the 80-mA setting for all children and 40 mA for children weighing 50 kg or less does not significantly affect the diagnosis of pediatric renal stones.

Renal candidiasis in neonates with candiduria.

BACKGROUND Candida species commonly cause urinary tract infection in infants admitted to neonatal intensive care units. The purpose of this study was to describe the natural history of renal candidiasis as evidenced by sonography in infants with candiduria. METHODS The medical records of all infants who developed candiduria during their neonatal intensive care hospitalization between 1982 and 1993 were reviewed. Candiduria was defined as the isolation of Candida from (1) one or more specimens obtained by bladder catheterization or suprapubic aspiration, (2) one or more voided specimens and concurrent positive cultures from another sterile body site or (3) one or more voided specimens and changes on renal ultrasound consistent with renal candidiasis. Renal ultrasounds were retrospectively reviewed by one pediatric radiologist. Nonshadowing echogenic foci were considered evidence of renal fungus balls. RESULTS Forty-one infants with candiduria were identified. Thirty-six infants underwent 1 or more renal imaging studies (ultrasonography, 35; computerized tomography, 1). The incidence of renal candidiasis in neonates with candiduria, defined as renal fungus balls or renal fungal abscess, was 42%. Of the 13 patients who had sonographic abnormalities suggestive of renal fungus balls, 7 had abnormalities on the first ultrasound obtained after the discovery of candiduria, whereas 6 patients developed abnormalities between 8 and 39 days later. CONCLUSIONS Serial renal ultrasounds are required to reliably detect late appearing renal fungus balls in neonates with candiduria. Complications requiring surgical intervention, like urinary tract obstruction, were uncommon.

Neurodevelopmental Outcome of Infants With Unilateral or Bilateral Periventricular Hemorrhagic Infarction

OBJECTIVE: Periventricular hemorrhagic infarction (PVHI) is a major contributing factor to poor neurodevelopmental outcomes in preterm infants. We hypothesized that surviving infants with unilateral PVHI would have more favorable outcomes than those with bilateral PVHI. METHODS: This was a multicenter, retrospective study of infants who were admitted to 3 NICUs in North Carolina from 1998 to 2004. The clinical course and late neuroimaging studies and neurodevelopmental outcomes of 69 infants who weighed <1500 g and had confirmed PVHI on early cranial ultrasonography were reviewed. A predictive model for Bayley Scales of Infant Development, Second Edition, Mental Developmental Index (MDI) <70 was constructed by using radiologic and clinical variables. RESULTS: Infants with unilateral PVHI had higher median MDI (82 vs 49) and Psychomotor Developmental Index (53 vs 49) than infants with bilateral PVHI. Infants with unilateral PVHI were less likely to have severe cerebral palsy (adjusted odds ratio: 0.15 [95% confidence interval (CI): 0.05–0.45]) than infants with bilateral PVHI. Infants who had unilateral PVHI and developed periventricular leukomalacia and retinopathy of prematurity that required surgery had an increased probability of having MDI <70 compared with those without these complications (probability of MDI <70: 89% [95% CI: 0.64–1.00] vs 11% [95% CI: 0.01–0.28]). CONCLUSIONS: Infants with unilateral PVHI had better motor and cognitive outcomes than infants with bilateral PVHI. By combining laterality of PVHI, periventricular leukomalacia, and retinopathy of prematurity it is possible to estimate the probability of having an MDI <70, which will assist clinicians when counseling families.

Pediatric MDCT: Towards Assessing the Diagnostic Influence of Dose Reduction on the Detection of Small Lung Nodules

RATIONALE AND OBJECTIVES The purpose of this study was to evaluate the effect of reduced tube current (dose) on lung nodule detection in pediatric multidetector array computed tomography (MDCT). MATERIALS AND METHODS The study included normal clinical chest MDCT images of 13 patients (aged 1-7 years) scanned at tube currents of 70 to 180 mA. Calibrated noise addition software was used to simulate cases as they would have been acquired at 70 mA (the lowest original tube current), 35 mA (50% reduction), and 17.5 mA (75% reduction). Using a validated nodule simulation technique, small lung nodules of 3 to 5 mm in diameter were inserted into the cases, which were then randomized and rated independently by three experienced pediatric radiologists for nodule presence on a continuous scale ranging from zero (definitely absent) to 100 (definitely present). The observer data were analyzed to assess the influence of dose on detection accuracy using the Dorfman-Berbaum-Mets method for multiobserver, multitreatment receiver-operating characteristic (ROC) analysis and the Williams trend test. RESULTS The areas under the ROC curves were 0.95, 0.91, and 0.92 at 70, 35, and 17.5 mA, respectively, with standard errors of 0.02 and interobserver variability of 0.02. The Dorfman-Berbaum-Mets method and the Williams trend test yielded P values for the effect of dose of .09 and .05, respectively. CONCLUSION Tube current (dose) has a weak effect on the detection accuracy of small lung nodules in pediatric MDCT. The effect on detection accuracy of a 75% dose reduction was comparable to interobserver variability, suggesting a potential for dose reduction.

Global Health Training in Radiology Residency Programs

RATIONALE AND OBJECTIVES To measure perceptions of radiology residents regarding the imaging needs of the developing world and the potential role of an organized global health imaging curriculum during residency training. MATERIALS AND METHODS An electronic survey was created and then distributed to residents in accredited US radiology residency. RESULTS Two hundred ninety-four residents responded to the survey. A majority (61%) planned to pursue future international medical aid work, even though a similar proportion (59%) believed that they would be ill-prepared with their current training to pursue this career goal. The vast majority (91%) of respondents stated that their residency program offers no opportunities to participate in global health imaging experiences. Most surveyed residents felt that an organized global health imaging curriculum would improve understanding of basic disease processes (87%) and cost-conscious care (82%), prepare residents for lifelong involvement in global health (80%), and increase interpretative skills in basic radiology modalities (73%). If such a curriculum were available, most (62%) of surveyed residents stated that they would be likely or very likely to participate. Many (58%) believed the availability of such a program would have influenced their choice of residency program; a similar proportion of residents (75%) believed that the availability of a global health imaging curriculum would increase recruitment to the field of radiology. CONCLUSION Many radiology residents are motivated to acquire global health imaging experience, with most survey respondents planning to participate in global health initiatives. These data demonstrate an imbalance between the level of resident interest and the availability of global health imaging opportunities, and support the need for discussion on how to implement global health imaging training within radiology residency programs.

Voiding Cystography Practices and Preferences of North American Pediatric Urologists

PURPOSE Little consensus exists regarding the choice of a specific modality of voiding cystography in the evaluation and management of vesicoureteral reflux. We hypothesized that choices of pediatric urologists are based on technical factors of the studies themselves, as well as institutional factors unique to their hospital(s). Therefore, we surveyed pediatric urologists to determine their current practices and preferences of modalities of voiding cystography. MATERIALS AND METHODS We mailed an anonymous survey of 40 questions to all fellows of the American Academy of Pediatrics Section on Urology. RESULTS Surveys were returned from 186 of 301 fellows (62%). Of the respondents 57% were in academic, 30% in private and 13% in mixed practices. Given a choice of fluoroscopic voiding cystourethrography, radionuclide cystography and voiding ultrasonography, fluoroscopic voiding cystourethrography was preferred by 98% and 96% of respondents for initial evaluation of urinary tract infection in males and females, respectively, 96% for assessment of prenatal hydronephrosis, 54% for followup of vesicoureteral reflux, 59% for screening siblings, and 63% and 66%, respectively, after open and endoscopic correction of vesicoureteral reflux. Voiding ultrasonography was preferred by less than 10% of respondents in all groups, and radionuclide cystography was preferred by the remainder. Voiding images of the urethra, child-friendliness of staff, sensitivity and accuracy were factors most important in choosing a test. Of the respondents 83% reported full-time access to pediatric radiologists at their primary hospital, although a minority had full-time access to pediatric radiologists at additional institutions. Sedation was used in some or most cases by 29%, rarely by 56% and never by 15% of respondents. CONCLUSIONS Pediatric urologists prefer fluoroscopic voiding cystography in all situations to evaluate vesicoureteral reflux but the proportion varies by indication. Diagnostic and patient issues are of greater concern than radiation dose. Variability in access to pediatric radiologists and ability to obtain the desired study may also alter ordering practices.

Predictors of an Academic Career on Radiology Residency Applications

RATIONALE AND OBJECTIVES To evaluate radiology residency applications to determine if any variables are predictive of a future academic radiology career. MATERIALS AND METHODS Application materials from 336 radiology residency graduates between 1993 and 2010 from the Department of Radiology, Duke University and between 1990 and 2010 from the Department of Radiology, Stanford University were retrospectively reviewed. The institutional review boards approved this Health Insurance Portability and Accountability Act-compliant study with a waiver of informed consent. Biographical (gender, age at application, advanced degrees, prior career), undergraduate school (school, degree, research experience, publications), and medical school (school, research experience, manuscript publications, Alpha Omega Alpha membership, clerkship grades, United States Medical Licensing Examination Step 1 and 2 scores, personal statement and letter of recommendation reference to academics, couples match status) data were recorded. Listing in the Association of American Medical Colleges Faculty Online Directory and postgraduation publications were used to determine academic status. RESULTS There were 72 (21%) radiologists in an academic career and 264 (79%) in a nonacademic career. Variables associated with an academic career were elite undergraduate school (P = .003), undergraduate school publications (P = .018), additional advanced degrees (P = .027), elite medical school (P = .006), a research year in medical school (P < .001), and medical school publications (P < .001). A multivariate cross-validation analysis showed that these variables are jointly predictive of an academic career (P < .001). CONCLUSIONS Undergraduate and medical school rankings and publications, as well as a medical school research year and an additional advanced degree, are associated with an academic career. Radiology residency selection committees should consider these factors in the context of the residency application if they wish to recruit future academic radiologists.

Lung nodule detection in pediatric chest CT: Quantitative relationship between image quality and radiologist performance

PURPOSE To determine the quantitative relationship between image quality and radiologist performance in detecting small lung nodules in pediatric CT. METHODS The study included clinical chest CT images of 30 pediatric patients (0-16 years) scanned at tube currents of 55-180 mA. Calibrated noise addition software was used to simulate cases at three nominal mA settings: 70, 35, and 17.5 mA, resulting in quantum noise of 7-32 Hounsfield Unit (HU). Using a validated nodule simulation technique, lung nodules with diameters of 3-5 mm and peak contrasts of 200-500 HU were inserted into the cases, which were then randomized and rated independently by four experienced pediatric radiologists for nodule presence on a continuous scale from 0 (definitely absent) to 100 (definitely present). The receiver operating characteristic (ROC) data were analyzed to quantify the relationship between diagnostic accuracy (area under the ROC curve, AUC) and image quality (the product of nodule peak contrast and displayed diameter to noise ratio, CDNR display). RESULTS AUC increased rapidly from 0.70 to 0.87 when CDNR display increased from 60 to 130 mm, followed by a slow increase to 0.94 when CDNR display further increased to 257 mm. For the average nodule diameter (4 mm) and contrast (350 HU), AUC decreased from 0.93 to 0.71 with noise increased from 7 to 28 HU. CONCLUSIONS We quantified the relationship between image quality and the performance of radiologists in detecting lung nodules in pediatric CT. The relationship can guide CT protocol design to achieve the desired diagnostic performance at the lowest radiation dose.]

A pattern-based approach to bowel obstruction in the newborn

Intestinal obstruction is common in newborns, and the radiologist plays a critical role in the care of these children. Diagnosing and managing the potentially obstructed newborn can be challenging, especially given the myriad underlying pathologies that range from benign to acutely life-threatening. A familiarity with the most common diagnoses is essential, but equally important to the radiologist is a systematic approach to management of the child in this setting. We propose an approach based on the recognition of eight radiographic patterns, five upper gastrointestinal examination (UGI) patterns and four contrast enema patterns. Recognition of these patterns directs further imaging when necessary and allows triage of children who can be managed medically, those requiring elective or urgent surgery and those requiring emergent surgery.

Residency Postinterview Communications: More Harm Than Good?

T he National Resident Matching Program (NRMP) was designed to provide a fair, reproducible, and confidential means of matching medical students and graduate medical education programs. During the recruitment process, residency programs and applicants actively communicate with one another to gather information to make more informed decisions. When these communications occur after interviews, but before rank order lists are submitted, they are termed ‘‘postinterview communications.’’ To prevent abuse, the NRMP provides strict regulations regarding the content of these communications. Its official policy states, ‘‘Both applicants and programs may express their interest in each other; however, they shall not solicit verbal or written statements implying a commitment.’’ Additionally, neither party can suggest that his or her own rank order is contingent on promises from the other party (ie, the residency program promises to rank an applicant to match if the applicant promises to rank the program No. 1). Unfortunately, postinterview communications are frequently misleading, as applicants and training programs make false or ambiguous statements in order to garner some perceived benefit from the other party. Previously, the nature and prevalence of postinterview communications were presented from the perspective of the applicant. To address the alternative perspective, in 2014, we surveyed residency program directors in multiple specialties within our institution and nationally via specialty mailing lists about postinterview communications and the influence they have on the recruitment process. We achieved an overall response rate of 23.2% (268 of 1156), with 107 responses from pediatrics programs, 58 from diagnostic radiology, 45 from internal medicine, 26 from internal medicine–pediatrics, 17 from pathology, and 9 responses from other specialties (with 6 nonresponses). Communications From Applicants to Residency Programs