Ultrafast power Doppler imaging using subarray adaptive temporal multiply-and-sum (SA-TMAS) algorithm with phase compensation for blood flow preservation

High-lag autocorrelation estimation enhances noise suppression in ultrafast power Doppler imaging by exploiting the temporal coherence among Doppler ensembles. The temporal-multiply-and-sum (TMAS) algorithm can further suppress the noise level in high-lag power estimation but suffers from signal loss due to blood flow decorrelation. To overcome this, we propose a method to integrate phase compensation with subarray TMAS (SA-TMAS). In phase compensation, the phase shift of blood flow signal from different plane-wave transmit angles is corrected to improve the angular coherence within each ensemble. Moreover, the SA-TMAS helps to strengthen the temporal coherence among ensembles using a shorter temporal window to preserve the flow signals. Adaptive pt modulation in TMAS algorithm further avoids the excessive suppression of blood flow regions according to the correlation between the complementary transmit subset. The proposed SA-TMAS with phase compensation is validated using simulation and in-vivo datasets. Results show that the proposed SA-TMAS achieves noise suppression comparable to the original TMAS while effectively preserving vascular signals due to reduced flow decorrelation. Phase compensation further restores the power of high-velocity flow, enabling the high-contrast vascular images.