Incidental Findings in Head and Brain MRI of Military Pilots and Applicants: Consequences for Medical Flight Fitness.

INTRODUCTION: With improved imaging technology, the number of incidental findings detected in cerebral MRI is increasing. This is a challenge that the German Air Force has to deal with in the context of standardized MRI examinations of young pilot candidates and pilots.METHODS: The German Air Force Centre of Aerospace Medicine hosted a 2-d conference to develop recommendations and procedures for the handling of some of the most frequently encountered cerebral incidental findings.RESULTS: Radiological MRI findings from a total of 2724 routine examinations of the skull of pilots and pilot applicants (26.8 ± 10.6 yr old; range from 16 to 62; over 80% range from 17 to 33; 96% men) revealed that in 28.1% of the examinations, one or more incidental findings were discovered. For seven of the following categories of incidental findings, decision guidelines could be established: white matter hyperintensities (N = 393; prevalence 14.4%; 95% CI 13.11-15.75), pinealis cysts (317; 11.6%; 10.43-12.84), developmental venous anomalies (64; 2.3%; 1.78-2.92), cavernomas (15; 0.6%; 0.27-0.83), aneurysms (14; 0.5%; 0.25-0.78), cholesterol granulomas (22; 0.8%; 0.47-1.14), and heterotopias of the gray matter (6; 0.2%; 0.04-0.4).CONCLUSION: Considering pilots health and aviation safety, a waiver decision is often possible after thorough discussion, depending on the specific criteria of the incidental finding and of the type of license.Kühn S, Sönksen S-E, Noble H-J, Knopf H, Frischmuth J, Waldeck S, Müller-Forell W, Weber F, Bressem L. Incidental findings in head and brain MRI of military pilots and applicants: consequences for medical flight fitness. Aerosp Med Hum Perform. 2022; 93(5):450-457.

Incidental Finding Prevalences in 3-Tesla Brain and Spine MRI of Military Pilot Applicants.

INTRODUCTION: Incidental findings in brain and spine MRI are common. In aerospace medicine, pilot selection may be affected by improved sensitivity of modern MRI devices. We investigated the occurrence of medically unfit rates caused by incidental findings in military pilot applicants using a 3-Tesla scanner as compared to the outcomes of a lower field strength 1-Tesla device based on similar screening protocols.METHODS: A total of 3315 military pilot applicants were assessed by a standardized German Air Force Imaging Screening Protocol and retrospectively subdivided into two cohorts, one of which was assessed by 1-Tesla MRI (2012-2015; N 1782), while in the second cohort (2016-2019; N 1808), a 3-Tesla MRI was used. Cohorts were statistically analyzed relating to three entities of incidental findings: 1) intervertebral disc displacements, 2) intracerebral vessel malformations, and 3) other abnormal findings in the brain.RESULTS: Pooled prevalences of incidental findings in medically unfit applicants significantly increased by use of 3-Tesla MRI as compared to lower resolution 1-Tesla MRI. Regarding the spine, prevalences more than doubled (1.46 vs. 4.99%; P < 0.05) for intervertebral disc displacements. Similarly, prevalences of cerebral vessel malformations as well as other abnormal CNS incidental findings considerably increased by use of 3-Tesla MRI (0.28 vs. 1.67%; P < 0.05, and 5.12 vs. 9.80%; P < 0.05). Effect sizes and correlations were substantial in all conditions analyzed (Cohens d > 0.8; Pearsons r > 0.75).CONCLUSIONS: Our data suggest a strong dependency of incidental cerebrospinal findings on image resolution and sensitivity of MRI devices used for screening, which is enhanced by refined imaging protocols and followed by increased medical unfit rates in prospective aviators. Adjusted strategies in the assessment of such lesions are needed to redefine their natural history and physiological impact, and to optimize screening protocols for future pilot selection.Snksen S-E, Khn SR, Nobl H-J, Knopf H, Ehling J, Jakobs FM, Frischmuth J, Weber F. Incidental finding prevalences in 3-Tesla brain and spine MRI of military pilot applicants. Aerosp Med Hum Perform. 2021; 92(3):146152.

Incidental findings in magnetic resonance imaging of the brains of healthy young men.

BACKGROUND AND PURPOSE: To determine the frequency of serious intracranial abnormalities in a healthy young male population. METHODS: Cranial MRI of 2,536 healthy young males, mean age 20.5 years, all applicants for military flying duties in the German Air Force. RESULTS: The authors report a variety of morphological abnormalities in the brains of a large population of healthy young males, providing data on disease prevalence. Arachnoid cysts were found in 1.7% (95% CI 1.2 to 2.3%), vascular abnormalities in 0.51% (95% CI 0.29 to 0.9%), and intracranial tumors in 0.47% (95% CI 0.26 to 0.85%) of the applicants. No cerebral aneurysms were found. CONCLUSION: The prevalence of primary brain tumors seems to be higher, whereas the prevalence of intracranial aneurysms is lower than expected. Only a small percentage of the detected abnormalities require urgent medical attention.

Cranial MRI as a screening tool: findings in 1,772 military pilot applicants.

BACKGROUND: Beginning 1 January 2000, during the selection process, the German Air Force Institute of Aviation Medicine screens all applicants for flying duty using cranial MRI to rule out relevant intracranial abnormalities. Type and frequencies of abnormalities and aeromedical consequences are described. METHODS: An intracranial MRI is done on every applicant regardless of the findings of the physical examination. RESULTS: From 1 January 2001 to 31 December 2002 we investigated a total of 1,772 applicants with cranial MRI. All of these had normal findings in both the general medical and neurological examinations. We found that 81.7% (1,452) were normal, 9% (160) had variations of the norm, 8.4% (148) had findings of unknown significance (e.g., arachnoid cysts, white matter lesions, etc.), and only 0.7% (12) had definite abnormal findings (arteriovenous malformations, cavernomas, tumors). CONCLUSION: Evident pathological cases are rare. However, cranial MRI screening adds substantial new information, increasing the value of the initial examination and making it possible to extend the examination according to the clinical indications. This leads to a highly individualized appraisal of the applicant, thus increasing flight safety.