Tardus parvus waveforms in Doppler ultrasonography for hepatic artery stenosis after liver transplantation: can a new cut-off value guide the next step?

Abstract

PurposeConsidering the high false-positive diagnosis of the tardus parvus waveform (TPW) in Doppler ultrasonography (DUS) for hepatic artery stenosis (HAS) after liver transplantation (LT), this study aimed to determine clinical features and new cut-off values to help guide treatment.Materials and methodsThis retrospective study was approved by an Institutional Review Board. A total of 171 LT recipients were included and underwent DUS and either computed tomography angiography or digital subtraction angiography with an interval < 4 weeks at least 1 month post-LT. The DUS of 69 patients exhibited TPW [defined as resistive index (RI) < 0.5 and systolic acceleration time (SAT) > 0.08 s]. A multilevel likelihood ratio (LR) analysis was used to explore new cut-off values for DUS. In addition, abnormal liver function was considered additional evidence (defined as any liver enzyme > 3-fold of the upper limit of normal level or 2-fold increased). The results were stratified into three categories, category 1 (subjects with traditional TPW), category 2 (subjects with traditional TPW and abnormal liver function), and category 3 (subjects with traditional TPW and abnormal liver function, or with new cut-off values), and the diagnostic performance of each category was analyzed.ResultsThe LR analysis revealed new cut-off values of RI < 0.4 (LR = 10.58) or SAT > 0.12 s (LR = 16.46). The false-positive rates for categories 2 and 3 were significantly lower (7.6% vs. 18.1%, P = 0.038; 1.9% vs. 18.1%, P < 0.001, respectively) than those for category 1, while the sensitivity for category 2 was significantly lower (41.8% vs. 74.6%, P < 0.001; 41.8% vs. 61.2%, P = 0.038, respectively) than that for categories 1 and 3.ConclusionUsing either (1) RI < 0.4 or SAT > 0.12 s, or (2) traditional TPW (RI < 0.5 and SAT > 0.08 s) in the presence of abnormal liver functions as the DUS criteria for HAS will significantly decrease the false-positive rate compared to traditional TPW without a significant increase in the false-negative rate.

Prognostic value of ultrasound in early arterial complications post liver transplant

“…The specificity of the tardus-parvus waveform for diagnosing HAS is approximately 81.9%[ 16 ]. However, it should be borne in mind that a tardus-parvus waveform does not necessarily confirm the presence of HAS, as it can be observed in various conditions such as severe aortic atherosclerosis, arteriovenous fistulas, artery-bile duct fistulas, extensive collateral circulation, large-area hepatic necrosis, or systemic hypotension[ 17 ]. A more reliable diagnostic criterion for HAS is the measurement of high-velocity blood flow above 200 cm/s near the hepatic artery anastomosis (Figure 2 ).…”