Accurate measurement of the atrium of the lateral ventricle requires strict adherence to the correct imaging plane and caliper placement. Even small technical errors can change the measurement by 1–2 mm, potentially leading to misclassification.
Below are the most common mistakes encountered in clinical practice.
1️⃣ Measuring in the Wrong Plane
The atrial width must be measured in the true transventricular axial plane.
Common errors include:
- Measuring too superiorly (roof of the ventricle)
- Measuring too inferiorly (thalami level)
- Oblique slicing of the head
Oblique sections frequently exaggerate ventricular width.
2️⃣ Not Confirming CSP
The cavum septi pellucidi (CSP) should be clearly visualized in the correct plane.
If the CSP is not visible:
- The plane may be incorrect
- The gestational age may be too early
- There may be associated anomalies
Measurement without confirming the proper plane reduces reliability.
3️⃣ Incorrect Caliper Placement
The measurement must be:
- Inner edge to inner edge
- Perpendicular to the long axis of the ventricle
- Taken at the level of the glomus of the choroid plexus
Common mistakes:
- Including the outer wall
- Placing the caliper obliquely
- Measuring diagonal distance
4️⃣ Including the Choroid Plexus
The choroid plexus should not be included in the measurement.
The atrial width is measured across the ventricular cavity only.
High gain settings may make the choroid plexus appear fused with the wall, leading to underestimation or overestimation.
5️⃣ Measuring Only One Side
When the measurement is borderline (9–10 mm):
- Both ventricles should be assessed
- Re-measure after slight probe adjustment
- Confirm symmetry
Small angulation differences can change the result significantly.
6️⃣ Overreacting to a Single Borderline Measurement
A measurement of 10 mm does not automatically indicate pathology.
Proper follow-up and repeat measurement are often more important than immediate labeling.
Clinical Tip
Before reporting mild ventriculomegaly, always:
✔ Confirm the correct plane
✔ Re-measure after adjusting probe angle
✔ Ensure inner-to-inner caliper placement
✔ Check both sides
Precision reduces unnecessary parental anxiety.
