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Nakata Index
The Nakata index is a cross-sectional area of the left and right pulmonary artery in mm2 divided by total body surface area (BSA). Cross-sectional area is measured by (π × 2/diameter × magnification coefficient expressed for BSA). The cross-sectional area is calculated by using the formula, π × r2 × magnification coefficient where, r = radius or ½ of the measured PA diameters. Normal Nakata value is 330 +/− 30 mm2/BSA.
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Total Neo-pulmonary Artery Index [TNPAI]
Suggested as an indicator of postoperative RV/LV pressure ratio. TNPAI is calculated by determining the cross-sectional area of the PAs (as described by Nakata et.al.) and the MAPCAs and dividing the result by body surface area (mm2/m2). TNPAI = APC index + Nakata index / BSA Where, APC index is the sum of CSA of all usable APC’s N.B. − APC = aortopulmonary collaterals; CSA = Cross-sectional area