Thomas L. Slovis

Practice parameter: Neuroimaging of the neonate Report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society

Objective: The authors reviewed available evidence on neonatal neuroimaging strategies for evaluating both very low birth weight preterm infants and encephalopathic term neonates. Imaging for the preterm neonate: Routine screening cranial ultrasonography (US) should be performed on all infants of <30 weeks’ gestation once between 7 and 14 days of age and should be optimally repeated between 36 and 40 weeks’ postmenstrual age. This strategy detects lesions such as intraventricular hemorrhage, which influences clinical care, and those such as periventricular leukomalacia and low-pressure ventriculomegaly, which provide information about long-term neurodevelopmental outcome. There is insufficient evidence for routine MRI of all very low birth weight preterm infants with abnormal results of cranial US. Imaging for the term infant: Noncontrast CT should be performed to detect hemorrhagic lesions in the encephalopathic term infant with a history of birth trauma, low hematocrit, or coagulopathy. If CT findings are inconclusive, MRI should be performed between days 2 and 8 to assess the location and extent of injury. The pattern of injury identified with conventional MRI may provide diagnostic and prognostic information for term infants with evidence of encephalopathy. In particular, basal ganglia and thalamic lesions detected by conventional MRI are associated with poor neurodevelopmental outcome. Diffusion-weighted imaging may allow earlier detection of these cerebral injuries. Recommendations: US plays an established role in the management of preterm neonates of <30 weeks’ gestation. US also provides valuable prognostic information when the infant reaches 40 weeks’ postmenstrual age. For encephalopathic term infants, early CT should be used to exclude hemorrhage; MRI should be performed later in the first postnatal week to establish the pattern of injury and predict neurologic outcome.

Cancer Risks Associated With External Radiation From Diagnostic Imaging Procedures

The 600% increase in medical radiation exposure to the US population since 1980 has provided immense benefit, but increased potential future cancer risks to patients. Most of the increase is from diagnostic radiologic procedures. The objectives of this review are to summarize epidemiologic data on cancer risks associated with diagnostic procedures, describe how exposures from recent diagnostic procedures relate to radiation levels linked with cancer occurrence, and propose a framework of strategies to reduce radiation from diagnostic imaging in patients. We briefly review radiation dose definitions, mechanisms of radiation carcinogenesis, key epidemiologic studies of medical and other radiation sources and cancer risks, and dose trends from diagnostic procedures. We describe cancer risks from experimental studies, future projected risks from current imaging procedures, and the potential for higher risks in genetically susceptible populations. To reduce future projected cancers from diagnostic procedures, we advocate the widespread use of evidence‐based appropriateness criteria for decisions about imaging procedures; oversight of equipment to deliver reliably the minimum radiation required to attain clinical objectives; development of electronic lifetime records of imaging procedures for patients and their physicians; and commitment by medical training programs, professional societies, and radiation protection organizations to educate all stakeholders in reducing radiation from diagnostic procedures. CA Cancer J Clin 2012.

Perfect is the enemy of the very good.

ence on intelligent dose reduction in CT has been edited, references added, and, whenever possible, the names of those making comments inserted. The figures are discussed in the text and there are a few captions. The conference is presented in total as a baseline for information that all pediatric radiologists (and also all physicians taking care of children) should know. To us, the conference stressed these concepts:

Sonographic classification of intracranial hemorrhage. A prognostic indicator of mortality, morbidity, and short-term neurologic outcome

Sixty-two neonates diagnosed to have periventricular-intraventricular hemorrhage were classified by sonographic findings as follows: mild, confined to the subependymal region or accompanied by a small amount of blood in the normal-sized lateral ventricle (10); moderate, intermediate amount of blood in the enlarged lateral ventricle (26); and severe, hemorrhage filling the entire ventricle forming a cast (12) or intraventricular hemorrhage with an intracerebral extension (14). Twenty-six of 35 surviving neonates had posthemorrhagic hydrocephalus, and 11 infants required shunt insertion. The survival rate of neonates with periventricular-intraventricular hemorrhage and the incidence of posthemorrhagic hydrocephalus correlated with the severity of the hemorrhage (P less than 0.05). The highest mortality rate was seen in the group with ventricular casts. All surviving neonates with casts developed hydrocephalus. All surviving neonates with intracerebral hemorrhage developed porencephaly. The severity of the hemorrhage correlated with short-term neurologic outcome (P less than 0.05), the group most severely affected being the one with intracerebral extension of hemorrhage. The severity of the hemorrhage also correlated with abnormal ventricular size by sonography on follow-up (P less than 0.05). However, posthemorrhagic hydrocephalus and abnormal ventricular size on follow-up did not correlate with neurologic outcome in the moderate and severe hemorrhage groups.

Necrotizing enterocolitis in term infants

Despite the fact that necrotizing enterocolitis is considered a disease of premature infants, 20% of all affected infants at Babies Hospital over the past 20 years were products of term gestations. Two distinct subgroups of such infants were noted (1) five infants with congenital heart disease and/or congestive heart failure (e.g.hypoplastic left heart syndrome), all but one of whom developed the disease in the first week of life; (2) eight infants who developed the disease at a much later age after a protracted period of diarrhea. This histopathologic features of the disease in term infants are the same as those in premature infants. Further, the pathogenesis of the disease in term infants does not appear to differ basically from that in premature infants. These facts, lead away from the concept of NEC as a disease of simple etiology.

The ALARA concept in pediatric CR and DR: dose reduction in pediatric radiographic exams – A white paper conference Executive Summary

ALARA, an acronym for as low as reasonably achievable, is a philosophy of radiation-dose management. As the SPR continues to promote ALARA in pediatric CT, we have begun to examine other imaging modalities where the potential for dose reduction exists. Computed radiography (CR) and digital radiography (DR) are acquisition systems that replace conventional screen-film (SF) systems for projection radiography. In conventional radiography, the amount of radiation needed to produce an acceptable image is specific to the SF system and chemical processing conditions. In CR and DR, the acquisition process is separated from the display process, allowing these systems to produce acceptable images over a wide range of exposures. Unfortunately, the disconnection of acquisition from display also introduces the potential for systematic overexposure. In order to examine the risk that CR and DR pose in pediatric radiography and the potential for dose reduction, the SPR organized a second ALARA Conference. The conference, held in Houston, Texas, February 28, 2004 and was attended by 77 pediatric radiologists, medical physicists, radiologic technologists, imaging scientists, and engineers. The conference was made possible by unrestricted grants from 6 CR and DR manufacturers. The faculty consisted of four academic speakers, five industry speakers, and a speaker from the Food and Drug Administration. The industry speakers were provided a list of questions in order to focus their lectures on specific features of their products that were relevant to dose management in pediatric radiography.

Neuroimaging and Neurodevelopmental Outcome in Extremely Preterm Infants

BACKGROUND: Extremely preterm infants are at risk for neurodevelopmental impairment (NDI). Early cranial ultrasound (CUS) is usual practice, but near-term brain MRI has been reported to better predict outcomes. We prospectively evaluated MRI white matter abnormality (WMA) and cerebellar lesions, and serial CUS adverse findings as predictors of outcomes at 18 to 22 months’ corrected age. METHODS: Early and late CUS, and brain MRI were read by masked central readers, in a large cohort (n = 480) of infants <28 weeks’ gestation surviving to near term in the Neonatal Research Network. Outcomes included NDI or death after neuroimaging, and significant gross motor impairment or death, with NDI defined as cognitive composite score <70, significant gross motor impairment, and severe hearing or visual impairment. Multivariable models evaluated the relative predictive value of neuroimaging while controlling for other factors. RESULTS: Of 480 infants, 15 died and 20 were lost. Increasing severity of WMA and significant cerebellar lesions on MRI were associated with adverse outcomes. Cerebellar lesions were rarely identified by CUS. In full multivariable models, both late CUS and MRI, but not early CUS, remained independently associated with NDI or death (MRI cerebellar lesions: odds ratio, 3.0 [95% confidence interval: 1.3–6.8]; late CUS: odds ratio, 9.8 [95% confidence interval: 2.8–35]), and significant gross motor impairment or death. In models that did not include late CUS, MRI moderate-severe WMA was independently associated with adverse outcomes. CONCLUSIONS: Both late CUS and near-term MRI abnormalities were associated with outcomes, independent of early CUS and other factors, underscoring the relative prognostic value of near-term neuroimaging.

Upper airway obstruction in infants and small children. Improved radiographic diagnosis by combining filtration, high kilovoltage, and magnification.

Selective filtration, high kilovoltage, and fine focal spot magnification produce detailed radiographs of the airway of infants and small children. This technique has been applied to the study of upper airway obstruction in the glottic, subglottic, and supraglottic areas. Its great diagnostic yield is accompanied by a reduction in radiation dose compared to that of a nonfilter technique. The physical factors dictating choice of filter and film-screen combination are discussed.

Surveillance Computed Tomography Imaging and Detection of Relapse in Intermediate- and Advanced-Stage Pediatric Hodgkin's Lymphoma: A Report From the Children's Oncology Group

PURPOSE Children with Hodgkins lymphoma (HL) routinely undergo surveillance computed tomography (CT) imaging for up to 5 years after therapy, resulting in cost and radiation exposure, without clear benefit. The objective of this study was to determine the contribution of surveillance CT, as compared with clinical findings, to detection of disease recurrence. PATIENTS AND METHODS Two hundred sixteen patients, age ≤ 21 years old, were treated on the multicenter Pediatric Oncology Group 9425 trial. Data for patients who experienced relapse were retrospectively reviewed to determine whether imaging or clinical events prompted suspicion of disease recurrence. Correlation was made to disease stage, time to recurrence, relapse site, and overall survival (OS). Results With a median follow-up time of 7.4 years, 25 (11.6%) of 216 patients had experienced a relapse, of whom 23 experienced local relapse. Median time to relapse was 7.6 months (range, 0.2 to 48.9 months). Nineteen relapses (76%) were detected based on symptoms, laboratory or physical examination findings, and two relapses (8%) were detected by imaging within the first year after therapy. Only four patients (16%) had their recurrence detected exclusively by surveillance imaging after the first year. Six deaths occurred, all in patients who experienced relapse within the first year after therapy. No patient with a recurrence after 1 year off treatment has died, regardless of how the recurrence was detected. CONCLUSION The majority of pediatric HL relapses occurred within the first year after therapy or were detected based on change in clinical status. Detecting late relapse, whether by imaging or clinical change, did not affect OS. These findings indicate that CT is overused for routine surveillance of patients with HL.

Comparison of chloral hydrate and midazolam for sedation of neonates for neuroimaging studies.

In a crossover study of seven term neonates who had neuroimaging studies, chloral hydrate (75 mg/kg administered orally) was more efficacious (p<0.05) but similar with regard to toxic effects than midazolam (0.2 mg/kg administered intravenously). Thus newer drugs are not necessarily better, and monitoring is essential even after a single oral sedative dose.