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Andrea Salica is a surgeon whose published work connects aortic root anatomy with aortic valve repair. His European Hospital profile identifies his specialty as cardiac surgery, and his full name appears beside Ruggero De Paulis on their 2019 anatomical exposition.^[ref][ref]

The coauthored article distinguishes several anatomical references often compressed into one casual description of an annulus. Its figures separate the basal reference through the low points of the valve attachments, the outward-bulging aortic sinuses and the sinotubular junction. The attachment of the aortic valve is crown-shaped rather than one flat circular line. These distinctions make aortic root measurement-plane dependence a substantive measurement issue.^[ref]

An original geometric example explains why naming a measured diameter is insufficient. A circular opening with diameter 24 mm has area $\pi (12{)}^2\approx 452\mathrm{m}{\mathrm{m}}^2$. An ellipse with full axis lengths 24 and 30 mm has area $\pi (12)(15)\approx 565\mathrm{m}{\mathrm{m}}^2$, 25% larger. One 24 mm diameter is compatible with both geometries. These are stipulated shapes, not anatomical reference values or dimensions reported for a patient.

The example motivates recording the measurement plane, axis and shape assumptions alongside the number. A root dimension also does not itself measure coaptation, the contact of valve tissues during closure. Spatial organization and observed valve function are related observations with different definitions. Salica's verified contribution here is to the joint anatomical account; its coauthor list alone does not allocate each illustration or observation to one author.

Aortic root measurement-plane dependence is the change in a reported dimension caused by selecting a different anatomical level or imaging direction. Basal, sinus and sinotubular junction measurements describe different structures. Even at a fixed level, an oblique observation need not equal a dimension obtained in a plane perpendicular to the local vessel direction.

The anatomical exposition illustrates separate root measurement levels in an echocardiography view and distinguishes the basal and sinotubular boundaries.^[ref] The three-dimensional crown of leaflet attachments also differs from a single flat ring.^[ref]

An original ideal circular cylinder example isolates obliquity. Let the true perpendicular radius be $R$. A plane whose normal is tilted by angle $\theta$ from the cylinder axis cuts an ellipse with semiaxesThe longest apparent diameter is $2R/\cos \theta$. For a stipulated perpendicular diameter 30 mm and tilt 30 degrees, it is approximately 34.64 mm, 15.5% larger despite unchanged material geometry.

The ellipse's area is $\pi R^2/\cos \theta$. If the longest diameter were instead inserted into a circular-area formula, the estimate would be $\pi R^2/{\cos }^2\theta$, 33.3% above the true perpendicular area at 30 degrees. Measuring the area of the oblique cut and assuming a circular area from its longest diameter introduce different geometric factors.

An actual aortic root is curved, sinus-bearing and time-dependent; it is not a uniform circular cylinder. The example demonstrates one source of measurement dependence rather than providing a universal correction for patient images. Anatomical asymmetry, selected landmarks and phase of the cardiac cycle must also be recorded.

A reproducible comparison therefore identifies the root level, imaging plane, direction of the reported dimension and cardiac phase. Two numbers should not be treated as a growth observation until their measurement definitions are compatible; a change in plane can change a number without an underlying change in root size.