Accuracy of radiologists, nonradiologists, and laypeople for identifying children with cerebral cortical atrophy from "Mercator map" curved reconstructions of MRIs of the brain

Abstract

Background: Using text reports to communicate bilateral, symmetric, and zonal cortical brain atrophy in children with term hypoxic ischemic injury (HII) to parents and legal professionals contesting compensation rights can be difficult. Using standard cross-sectional images for explaining bilateral, regional brain imaging to laypeople is also challenging. A single flattened image of the brain surface, much like a map of the earth is derived from a globe, can be generated from curved reconstruction of magnetic resonance imaging (MRI) scans, i.e., a Mercator map. Laypeople's ability to identify abnormal "Mercator brain maps," without prior training, requires evaluation before use in nonmedical settings.

Aim: To determine the sensitivity and specificity of laypeople in detecting abnormal pediatric Mercator flat-earth maps of the brain, without prior training.

Methods and materials: 10 Mercator brain maps were provided to 111 participants individually. The maps comprised 5 HII, 1 cortical dysplasia, and 4 normal cases. Participants were required to identify the abnormal scans. Sensitivity and specificity overall and for participants' subgroups were calculated.

Results: Overall sensitivity and specificity were 67% and 80%, respectively. General radiologists (n = 12) had sensitivity and specificity of 91.2% and 94.6%, respectively. Laypeople (n = 54) had a sensitivity of 67% and specificity of 80%.

Conclusion: The high specificity and sensitivity of radiologists validated the technique for distinguishing abnormal scans, regarding cortical pathology. High specificity of laypeople for identifying abnormal brains using Mercator maps indicates that this is a viable communication tool for demonstrating cortical MRI abnormalities of HII in children to laypersons.

Keywords: Cerebral cortical atrophy; HII; MRI; Mercator map; curved reconstructions; hypoxic ischemic injury; laypeople.

Figure 1 (A and B)

(A and B) Pathway for creating a flat earth map and the layout of the anatomy. (A) The reconstruction pathway according to Simpson et al.[5] is plotted in a curved pathway along the outer centimeter of the brain at the level of the 3^rd ventricle on a coronal planning slice. (B) The resultant Mercator/flat earth map demonstrates the entire brain surface laid flat with the temporal lobes seen laterally (T) and separated from the frontal lobes by the Sylvian fissures (straight arrows), the parasagittal regions seen at the top of the image along each side of the midline (curved arrows), and the peri-Rolandic regions seen at the bottom of the image, on each side of the midline (dotted oval)

Figure 2

The grid of arbitrarily organized Mercator/flat earth images numbered from 1–10, which were shown to participants, who were asked to indicate any that they thought were abnormal. The grid comprises 10 children of varying ages, 5 of whom had suffered partial prolonged hypoxic ischemic injury (HII) at term (panels 2, 4, 5, 8, and 10), one child with peri-Sylvian cortical dysplasia (panel 7), and 4 children with “normal” MRI reports (1, 3, 6, and 9)

Figure 3 (A and B)

(A and B) Comparison of Mercator/flat earth map of a child with partial prolonged hypoxic ischemic injury with that of a child who had a normal MRI report. (A) The Mercator/flat earth map if this 2-year-old child with partial prolonged hypoxic ischemic injury at birth demonstrates bilateral atrophy (thinning) of the peri-Rolandic cortex (straight arrows), localized separation of the hemispheres due to anterior para-sagittal atrophy with associated ulegyria (curved arrows) and prominence of the Sylvian fissures due to peri-Sylvian atrophy (asterisks). (B) In contrast, the Mercator/flat earth map of the child with the normal MRI scan demonstrates closely apposed pre- and post-central gyri, closely apposed hemispheres along the falx cerebri, and closely apposed temporal and frontal lobes at the Sylvian fissures. There is no prominence of the surface markings, indicating normal volume of the brain at these specific locations