Earlobe Inferior Margin as a Landmark for Cerebellar Visualization in Brain Perfusion SPECT

Area of Science:

• Nuclear Medicine
• Radiology
• Neuroimaging

Background:

• Accurate interpretation of brain perfusion SPECT requires consistent cerebellar inclusion.
• The anatomical validity of external head landmarks for patient positioning in SPECT has not been quantitatively assessed.
• Reliable landmarks are needed for reproducible craniocaudal head positioning.

Purpose of the Study:

• To quantitatively evaluate the spatial relationships between external head landmarks and the cerebellar inferior margin.
• To identify a stable external landmark for reproducible head positioning in brain perfusion scintigraphy.

Main Methods:

• Retrospective analysis of 100 preoperative brain tumor CT studies.
• Measurement of z-coordinates for eyeball center, inferior earlobe margin, nasal base, external auditory meatus, and inferior cerebellar margin.
• Calculation of differences between landmark z-coordinates and a tilt index.

Main Results:

• The inferior margin of the earlobe was consistently located caudal to the cerebellum.
• The inferior earlobe margin exhibited low variability in its position relative to the cerebellum.
• The inferior earlobe margin showed the weakest association with variations in neck posture.

Conclusions:

• The inferior margin of the earlobe serves as a stable and reproducible landmark for craniocaudal head positioning.
• Utilizing the inferior earlobe margin can support consistent cerebellar coverage in brain perfusion scintigraphy.
• This finding aids in improving the accuracy of brain perfusion SPECT interpretations.