Dark, diamond-shaped spots seen on inner ear magnetic resonance imaging (MRI) scans do not always indicate disease. Instead, they may simply reflect how a patient’s head is positioned inside the scanner. A pilot study conducted at Karl Landsteiner University of Health Sciences (KL Krems) demonstrates that these characteristic “flow void” artifacts become significantly more pronounced when the head is tilted backward and diminish when the chin is tilted downward. Notably, some participants also experienced mild dizziness when their heads were extended.
The findings support the hypothesis that strong magnetic fields can induce fluid motion within the inner ear. Importantly, they also highlight the need to consider head position when interpreting brain and inner ear MRI scans—and when optimizing patient comfort during high-field imaging.
Understanding Magnetic Effects in High-Field MRI
Today, high-field MRI at 3 Tesla (3T) and above represents the standard in neuroradiology. At these higher field strengths, the static magnetic field interacts with tiny ionic currents in the inner ear fluids. As a result, so-called Lorentz forces arise.
These forces can trigger nystagmus—uncontrolled rhythmic eye movements—and vertigo in individuals with a healthy vestibular system. At the same time, MRI sequences used to visualize the inner ear’s labyrinth remain highly sensitive to even subtle fluid motion.
Earlier observations in Krems identified small, sharply defined low-signal areas in the vestibule that did not correspond to any known anatomical structure. Researchers labeled these areas as hypointensities or “flow voids.” Therefore, the new study systematically examined whether these findings truly represent flow-related artifacts and whether they vary consistently with head pitch.
Designing a Controlled Pilot Study
A multidisciplinary team jointly led by Prof. Dr. Domagoj Javor, Head of the Institute of Diagnostic and Interventional Radiology, and Dr. Béla Büki from the Division of Otorhinolaryngology at University Hospital Krems examined 20 healthy adults without known vestibular disorders.
As per the press release, the researchers intentionally kept the sample size small and described the work as a proof-of-principle rather than a definitive clinical trial. Each volunteer underwent two high-resolution inner ear scans in a 3T MRI scanner using a T2-weighted SPACE sequence.
First, participants positioned their chins toward their chests (head flexion). Then, they repeated the scan with their heads tilted backward (head extension). The team reconstructed the images in the plane of the horizontal semicircular canal.
Subsequently, two experienced radiologists independently and blindly assessed the images. They measured the proportion of the vestibule occupied by the hypointense “flow void” areas.
Head Extension Increases the Artifact
The results revealed a consistent pattern. When participants tilted their heads backward, the low-signal area within the vestibule increased by approximately 15 percentage points on both sides compared with the chin-down position.
Moreover, three out of the 20 volunteers—about 15 percent—reported mild vertigo while their heads were extended. In contrast, none experienced dizziness during head flexion.
According to Prof. Dr. Javor, these findings confirm that the small, dark vestibular spots do not represent fixed anatomical features. Instead, they vary with head position in the magnetic field. Consequently, this behavior strongly supports the interpretation of these findings as benign, position-dependent artifacts rather than pathological inner ear lesions.
The Physics Behind the Phenomenon
From a physical standpoint, the observations align with established models of magnetic vestibular stimulation. When a patient tilts the head backward, the primary direction of ionic currents within the inner ear becomes more perpendicular to the scanner’s magnetic field.
This orientation increases the Lorentz force acting on the ions. As a result, endolymph fluid movement intensifies, particularly in the utricle and the lateral semicircular canal.
Such fluid motion can deflect the cupulae—gelatinous structures involved in balance perception—thereby contributing to vertigo. Simultaneously, the motion can disrupt MRI signal acquisition, leading to more prominent flow void artifacts.
Clinical Implications and Practical Recommendations
Given these findings, the authors propose a practical strategy for daily clinical practice. If a suspicious hypointensity appears in the vestibule on a T2-weighted spin-echo sequence, radiologists should assess whether the finding changes with head position or differs across MRI sequence types.
For example, gradient-echo sequences—less sensitive to slow fluid motion—can serve as a useful comparison. Additionally, documenting head pitch on sagittal localizer images and reconstructing scans in the plane of the horizontal semicircular canal can improve left–right comparisons.
As Dr. Béla Büki emphasizes, this characteristic diamond-shaped hypointensity often increases with head extension and decreases with flexion. Therefore, when seen in isolation, it may mimic a focal lesion—but in many cases, it simply reflects fluid motion induced by a strong magnetic field.
Recognizing the Study’s Limitations
Despite its internal consistency, the study has important limitations. Researchers conducted it at a single center using one 3T scanner and one specific T2 SPACE protocol. Furthermore, they examined only 20 healthy volunteers.
The design of the head coil restricted the range of head positions. In addition, the team did not directly measure eye movements or inner ear fluid dynamics.
For these reasons, the authors stress that their work represents a pilot investigation rather than a new standard of care. Larger studies at different field strengths—and, crucially, investigations involving patients with vestibular disorders—will be necessary to validate and extend these findings.
Interdisciplinary Collaboration Driving Insight
Nevertheless, the study demonstrates how collaboration between radiology, otorhinolaryngology, and vestibular research can transform a physical side effect of modern MRI into practical clinical guidance.
At KL Krems and University Hospital Krems, clinicians already incorporate these insights into teaching, protocol planning, and patient management. Ultimately, by recognizing position-dependent MRI artifacts, radiologists can avoid misdiagnosis, refine imaging protocols, and improve patient comfort during high-field scanning.