Incidental findings on routine brain MRI scans in preterm infants

Neuroimaging at Term Equivalent Age: Is There Value for the Preterm Infant? A Narrative Summary

Advances in neuroimaging of the preterm infant have enhanced the ability to detect brain injury. This added information has been a blessing and a curse. Neuroimaging, particularly with magnetic resonance imaging, has provided greater insight into the patterns of injury and specific vulnerabilities. It has also provided a better understanding of the microscopic and functional impacts of subtle and significant injuries. While the ability to detect injury is important and irresistible, the evidence for how these injuries link to specific long-term outcomes is less clear. In addition, the impact on parents can be profound. This narrative summary will review the history and current state of brain imaging, focusing on magnetic resonance imaging in the preterm population and the current state of the evidence for how these patterns relate to long-term outcomes.

An assessment of prevalence and expenditure associated with discharge brain MRI in preterm infants

To assess national expenditure associated with preterm-infant brain MRI and potential impact of reduction per Choosing Wisely campaign 2015 recommendation to “avoid routine screening term-equivalent or discharge brain MRIs in preterm-infants”. Cross-sectional U.S. trend data from the Agency for Healthcare Research and Quality (AHRQ), Healthcare Cost and Utilization Project (HCUP) Kids’ Inpatient Database (KID) database (2006, 2009, 2012, 2016) was used to estimate overall national expenditure associated with brain MRI among infants with gestational age (GA) ≤36 weeks, and also when classified as ‘not indicated’ (NI-MRI) i.e., equivalent to routine use without clinical indications and regarded as low-value service (LVS). Associated cost was determined by querying CMS-database for physician-fee-schedules to find the highest global procedure-cost per cycle, then adjusting for inflation. Sensitivity-analyses were conducted to account for additional clinical charges associated with NI-MRI. 3,768 (0.26%) of 1,472,236 preterm-infants had brain MRI across all cycles (inflation-adjusted total $3,690,088). Overall proportion of brain MRIs increased across 2006–2012 from 0.25%-0.33% but decreased in 2016 to 0.16% (P<0.001). Inflation-adjusted overall expenditure by cycle was: 2006, $1,299,130 (95% CI: $987,505, $1,610,755); 2009, $1,194,208 (95% CI: $873,487, $1,516,154); 2012, $931,836 (95% CI: $666,114, $1,197,156); and 2016, $264,648 (95% CI: $172,061, $357,280). Prevalence for NI-MRI in 2006, 2009, 2012 and 2016 was 86% (n = 809), 88% (n = 940), 89% (n = 1028) and 50% (n = 299), respectively; and 70% were in infants 35–36 weeks GA. NI-MRI prevalence was not different over time by payer-type (Medicaid, private), sex or race/ethnicity (white, black, Hispanic); larger hospital size was significantly associated across 2006–2012 but this declined for all sizes in 2016, with most decline in larger hospitals (P for interaction <0.05). NI-MRI expenditure sensitivity-analysis with addition of cycle median total-admission-charge to inflation-adjusted CMS-fee was $1,190,919/$518,343, for 2012/2016 cycles respectively. National MRI prevalence in preterm infants (both overall and LVS) and associated expenditure decreased substantially post recommendation; however, annual savings are modest and unlikely to be >$1.2 million.

Neonatal Developmental Venous Anomalies: Clinicoradiologic Characterization and Follow-Up

BACKGROUND AND PURPOSE

Although developmental venous anomalies have been frequently studied in adults and occasionally in children, data regarding these entities are scarce in neonates. We aimed to characterize clinical and neuroimaging features of neonatal developmental venous anomalies and to evaluate any association between MR imaging abnormalities in their drainage territory and corresponding angioarchitectural features.

MATERIALS AND METHODS

We reviewed parenchymal abnormalities and angioarchitectural features of 41 neonates with developmental venous anomalies (20 males; mean corrected age, 39.9 weeks) selected through a radiology report text search from 2135 neonates who underwent brain MR imaging between 2008 and 2019. Fetal and longitudinal MR images were also reviewed. Neurologic outcomes were collected. Statistics were performed using χ², Fisher exact, Mann-Whitney U, or t tests corrected for multiple comparisons.

RESULTS

Developmental venous anomalies were detected in 1.9% of neonatal scans. These were complicated by parenchymal/ventricular abnormalities in 15/41 cases (36.6%), improving at last follow-up in 8/10 (80%), with normal neurologic outcome in 9/14 (64.2%). Multiple collectors (P = .008) and larger collector caliber (P < .001) were significantly more frequent in complicated developmental venous anomalies. At a patient level, multiplicity (P = .002) was significantly associated with the presence of ≥1 complicated developmental venous anomaly. Retrospective fetal detection was possible in 3/11 subjects (27.2%).

CONCLUSIONS

One-third of neonatal developmental venous anomalies may be complicated by parenchymal abnormalities, especially with multiple and larger collectors. Neuroimaging and neurologic outcomes were favorable in most cases, suggesting a benign, self-limited nature of these vascular anomalies. A congenital origin could be confirmed in one-quarter of cases with available fetal MR imaging.

The efficacy of routine brain MRI for term neonates admitted to neonatal intensive care unit

OBJECTIVE

The efficacy of routine brain MRI for term infants admitted to a neonatal intensive care unit (NICU) has not been well studied. This study aimed to investigate the types and frequencies of abnormal findings on routine brain MRI and the predictors of abnormality for term infants in an NICU setting.

METHODS

We examined the results of routine brain MRI of 239 term infants who were hospitalized in the NICU. Data on the perinatal factors were also collected, and the association with MRI abnormalities was assessed.

RESULTS

Of the 239 MRI scans, we found abnormal findings in 52 (21.8%) patients. Intracranial hemorrhage accounted for 74% of the abnormal findings, including subdural, intraparenchymal, cerebellar, and subependymal hemorrhages. Twenty-six percent of these were ischemic lesions, including cerebral infarction, white matter abnormal intensities, and cystic periventricular leukomalacia (PVL). Five (2.1%) MRI scans required detailed examination or were known to be associated with a poor neurological prognosis. No patient needed treatment for the findings. An Apgar score ≤7 points at 5 min was identified as a perinatal factor significantly associated with abnormal MRI findings (adjusted OR = 3.034, 95% CI: 1.107-8.315, p = .031).

CONCLUSION

The efficacy of routine brain MRI for term infants admitted to the NICU was limited. Routine brain MRI is not recommended for this population.

Prevalence and Risk Factors of Incidental Findings in Brain MRIs of Healthy Neonates-The FinnBrain Birth Cohort Study

Background: Birth is a traumatic event with molding forces directed to the fetal skull, which may result in intracranial hemorrhages. However, the knowledge on prevalence and risk factors of incidental brain magnetic resonance imaging (MRI) findings in infants is still inconclusive.

Methods: The prevalence and nature of incidental MRI findings were assessed in a birth cohort of 175 asymptomatic infants. The role of delivery method as well as other potential risk factors for intracranial hemorrhages were evaluated. The infants underwent 3T MRI at the age of 2–5 weeks, and the neurological status of the infants with an incidental finding was evaluated by a pediatric neurologist. Information on the delivery method, duration of delivery, parity, used anesthesia, oxytocin induction, and Apgar score was gathered to evaluate their association with the prevalence of hemorrhages.

Results: Incidental intracranial hemorrhages were detected in 12 infants (6.9%), all following spontaneous or assisted vaginal delivery. Vacuum-assistance was found to be a risk factor for subdural hemorrhages with an odds ratio (OR) of 4.7 (95% CI [1.18; 18.9], p = 0.032). All infants were evaluated to develop normally by their clinical status.

Conclusions: Incidental intracranial hemorrhages are relatively common among infants born by vaginal delivery. They are often of little clinical significance within the first years of life and have unlikely consequences for later neurodevelopment either. Despite their benign character, investigators should be prepared to share this information with parents competently as the findings can cause parental anxiety, and especially as the popularity of MRI as a research tool is increasing.

Incidental Findings on Brain Magnetic Resonance Imaging in Preterm Infants

BACKGROUND

In recent years, many neonatal intensive care units have adopted the practice of routinely performing brain magnetic resonance imaging (MRI) of extremely preterm (EP) infants at term-equivalent age (TEA). This practice may result in increased identification of incidental findings (IF).

OBJECTIVES

To determine the prevalence and clinical significance of incidental findings on routine MRI of EP infants.

METHODS

We retrospectively reviewed findings on routine brain MRI on 165 EP infants at TEA (gestation < 28 weeks) admitted between June 2015 and December 2017.

RESULTS

Incidental findings were detected in 16/165 (9.7%) infants. This included 9 cases that were clinically significant: 7 (with upper spinal cord abnormalities in 3, a choroid plexus lesion in 1, a pituitary abnormality in 1, and cerebral aqueduct narrowing in 2) required diagnostic intervention, and 2 (1 with an extramedullary arachnoid cyst and 1 with endolymphatic sac dilatation with a hypoplastic cochlear nerve) required diagnostic and therapeutic interventions. The incidental findings in the other 7 cases (a venous anomaly in 2, corpus callosum dysgenesis in 1, an absent septum pellucidum in 2, a frontal scalp mass in 1, and a nasal septum cyst in 1) were not clinically significant.

CONCLUSIONS

Incidental findings were not uncommon on routine brain MRI of EP infants at TEA in our cohort. While most were clinically insignificant, some did require further diagnostic and therapeutic interventions. Prospective large studies on the prevalence and clinical significance of incidental findings on routine brain MRI of EP infants at TEA are required for developing evidence-based management plans and for counselling parents.

Torcular pseudomass: a potential diagnostic pitfall in infants and young children

BACKGROUND

Incidental findings on brain MRI may constitute a diagnostic pitfall. We observed an incidental extra-axial midline rounded pseudomass between the torcular Herophili and the occipital squama, with spontaneous resolution, which we called "torcular pseudomass."

OBJECTIVE

We investigated the frequency, imaging features, natural history and developmental background of this finding in a large group of infants and young children.

MATERIALS AND METHODS

We conducted a single-center retrospective study by reviewing all brain MRIs performed in children younger than 3 years between 2007 and 2013 in a specialized pediatric hospital. We looked for soft tissue (minimum 2 mm thick) interposed between the torcula and the occipital squama on midsagittal T1 and T2 images; we recorded the maximal diameters and outcome.

RESULTS

Of 2,283 the children who had brain MRIs during the study period, 291 (12.7%, 95% confidence interval [CI] 0.11, 0.14) presented with a torcular pseudomass (median age 4 months, range 0 days to 35 months, 56% male). MRI features were the same in all of these children: T1 isointensity and T2 hyperintensity to the cerebral cortex, facilitated diffusion on diffusion-weighted imaging and apparent diffusion coefficient maps, and contrast enhancement. The median diameters were: anteroposterior, 5.8 mm; transverse, 10.5 mm; cranio-caudal, 20.6 mm. Follow-up MRI was available in 34.7% (95% CI: 0.20, 0.40) of the children; median follow-up time was 18 months. Among these children, 35.6% (95% CI: 0.26, 0.45) had total involution, 52.5% (95% CI: 0.26, 0.62) had partial involution and 4.1% (95% CI: 0.05, 0.18) showed stability.

CONCLUSION

Redundant soft tissue in the torcular region, or torcular pseudomass, is not an infrequent finding in infants and young children. It should be considered a physiological tissue, reflecting the postnatal developmental process of the brain and cranial vault, without the need for further investigation or follow-up imaging studies.