Date Published: October 23, 2017
Publisher: Springer US
Author(s): Bo-wen Zheng, Ying-yi Tan, Bin-sheng Fu, Ge Tong, Tao Wu, Li-li Wu, Xiao-chun Meng, Rong-qin Zheng, Shu-hong Yi, Jie Ren.
Considering 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.
This 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.
The 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. Using 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.
A total of 1654 liver transplants were performed in patients between March 2004 and March 2015. Patients were included in the study if they underwent DUS and a follow-up computed tomography angiography (CTA) or digital subtraction angiography (DSA) within a 4-week interval at least 1 month after the LT for a targeted evaluation of the hepatic arteries based on the present diagnostic procedure at our institution, as mentioned above (Fig. 1). If there were multiple examinations, the earliest pair was selected for each liver. A total of 190 transplanted livers in 189 patients fulfilled the inclusion criteria. Examination pairs were excluded for the following reasons: undetectable flow signal in both left and right hepatic arteries or quantitative parameters derived despite the documentation of arterial flow (n = 13); and unavailability of angiographic images in our picture archiving and communication system (PACS) (n = 5). The remaining 172 transplanted livers in 171 patients (total mean age 47 years ± 12, age range 7–71 years), including 146 men (mean age 47 years ± 11, age range 7–71 years) and 25 women (mean age 44 years ± 13, age range 16–64 years) (P = 0.334 for sex difference), constituted our study population. One patient underwent two LTs in an interval of 56 months. Out of these patients, 161 underwent deceased-donor LT, and the remaining patients underwent living-donor LT using modified right-lobe (n = 8) or left-lobe (n = 1) grafts. Indications for LT included hepatocellular carcinoma (n = 88), liver cirrhosis associated with hepatitis B or C virus (n = 32), fulminant hepatic failure (n = 39), Wilson’s disease (n = 2), alcoholic liver disease (n = 3), autoimmune liver disease (n = 2), polycystic liver disease (n = 1), congenital cirrhosis (n = 1), hepatoblastoma (n = 1), biliary stricture (n = 2), and liver metastases (n = 1).
We found that applying the traditional TPW criterion defined by Dodd III et al.  as a TPW with RI < 0.5 and SAT > 0.08 s indeed led to a high false-positive rate of 18.1%, which is identical to that in previous studies [10, 18]. The high false-positive rate indicates that a number of patients with TPW should not require treatment or further examinations. To avoid unnecessary management, the combination of TPW and additional abnormal liver function (category 2) for depicting HAS is now applied at our institution (Fig. 1). The false-positive rate indeed decreased to 7.6%. However, sensitivity also decreased from 74.6% to 41.8%, possibly because of a slow progression of these HAS cases with unapparent evaluated liver function within a few days, which also caused delayed management for these high-risk patients in our research.