Changes in portal hemodynamics and acute rejection in the first 2 weeks after orthotopic liver transplantation. A prospective Doppler ultrasound study

Usefulness of Diffusion-Weighted Imaging in Evaluating Acute Cellular Rejection and Monitoring Treatment Response in Liver Transplant Recipients

Acute cellular rejection (ACR) is a significant immune issue among recipients following liver transplantation. Although diffusion-weighted magnetic resonance imaging (DWI) is widely used for diagnosing liver disease, it has not yet been utilized for monitoring ACR in patients after liver transplantation. Therefore, the aim of this study was to evaluate the efficacy of DWI in monitoring treatment response among recipients with ACR. This study enrolled 25 recipients with highly suspected ACR rejection, and all subjects underwent both biochemistry and DWI scans before and after treatment. A pathological biopsy was performed 4 to 24 h after the first MRI examination to confirm ACR and degree of rejection. All patients were followed up and underwent a repeated MRI scan when their liver function returned to the normal range. After data acquisition, the DWI data were post-processed to obtain the apparent diffusion coefficient (ADC) map on a voxel-by-voxel basis. Five regions of interest were identified on the liver parenchyma to measure the mean ADC values from each patient. Finally, the mean ADC values and biochemical markers were statistically compared between ACR and non-ACR groups. A receiver operating characteristic (ROC) curve was constructed to evaluate the performance of the ADC and biochemical data in detecting ACR, and correlation analysis was used to understand the relationship between the ADC values, biochemical markers, and the degree of rejection. The histopathologic results revealed that 20 recipients had ACR, including 10 mild, 9 moderate, and 1 severe rejection. The results demonstrated that the ACR patients had significantly lower hepatic ADC values than those in patients without ACR. After treatment, the hepatic ADC values in ACR patients significantly increased to levels similar to those in non-ACR patients with treatment. The ROC analysis showed that the sensitivity and specificity for detecting ACR were 80% and 95%, respectively. Furthermore, the correlation analysis revealed that the mean ADC value and alanine aminotransferase level had strong and moderate negative correlation with the degree of rejection, respectively (r = -0.72 and -0.47). The ADC values were useful for detecting hepatic ACR and monitoring treatment response after immunosuppressive therapy.

Serial measurement of Doppler hepatic hemodynamic parameters for the diagnosis of acute rejection after live donor liver transplantation

To elucidate the role of Doppler hepatic hemodynamic parameters as surrogate markers of acute rejection (AR) after live donor liver transplantation (LDLT), serial Doppler measurements were prospectively performed during the first 2 weeks after LDLT to compare the longitudinal hepatic hemodynamic changes between patients with histologically proven AR and patients without histologically proven AR. Forty-six patients that had undergone adult-to-adult LDLT using a right lobe graft were enrolled in this study. The portal venous maximum velocity (PVV; cm/second), portal venous flow volume, hepatic arterial peak systolic velocity, hepatic arterial pulsatility index, hepatic venous maximum velocity, hepatic venous pulsatility index, and splenic arterial pulsatility index were measured. Fourteen patients were diagnosed by biopsy to have clinically relevant AR. Markedly increased PVV was seen soon after surgery and gradually decreased in both patients with clinically relevant AR and patients without clinically relevant AR. This serial change of decreasing PVV was significantly greater in patients with clinically relevant AR (P < 0.0001). After postoperative day 6, the PVV in patients with clinically relevant AR was significantly lower than that in patients without clinically relevant AR (PVV on postoperative day 6: 35.6 +/- 21.3 versus 58.3 +/- 27.1 cm/second, respectively, P = 0.0080). A PVV cutoff value of 20.2 cm/second demonstrated the best accuracy for predicting clinically relevant AR. The sensitivity and specificity for predicting clinically relevant AR were 92.9% and 87.1%, respectively. The area under the curve was 0.94. In conclusion, serial Doppler measurement of hepatic parameters in LDLT is useful for the diagnosis of clinically relevant AR. Clinically relevant AR should therefore be suspected when a marked unexpected decrease in the PVV is observed.

CT perfusion at early stage of hepatic diffuse disease

AIM: To determine the validity of the non-invasive method of CT perfusion (CTP) in rat model of hepatic diffuse disease.

METHODS: Twenty-eight Wistar rats were divided into two groups. Liver diffuse lesions were induced by diethyln-itrosamine in 14 rats of test group. Rats in control group were bred with pure water. From the 1^st to 12^th wk after the test group was intervened, both groups were studied every week with CTP. CTP parameters of liver parenchyma in different periods and pathologic changes in two groups were compared and analyzed.

RESULTS: The process of hepatic diffuse lesions in test groups was classified into three stages or periods according to the pathologic alterations, namely hepatitis, hepatic fibrosis, and cirrhosis. During this period, hepatic artery flow (HAF) of control group declined slightly, mean transit time (MTT), blood flow (BF) and volume (BV) increased, but there were no significant differences between different periods. In test group, HAF tended to increase gradually, MTT prolonged obviously, BV and BF decreased at the same time. The results of statistical analysis revealed that the difference in the HAF ratio of test group to control group was significant. The ratio of BV and BF in test group to control group in stage of hepatitis and hepatic cirrhosis, hepatic fibrosis and early stage of hepatic cirrhosis was significantly different, but there was no significant difference between hepatitis and hepatic fibrosis. The main pathological changes in stage of hepatitis were swelling of hepatic cells, while sinusoid capillarization and deposition of collagen aggravated gradually in the extravascular Disse’s spaces in stage of fibrosis and early stage of cirrhosis.

CONCLUSION: The technique could reflect some early changes of hepatic blood perfusion in rat with liver diffuse disease and is valuable for their early diagnosis.

Acute Liver Rejection: Accuracy and Predictive Values of Doppler US Measurements—Initial Experience

PURPOSE

To prospectively evaluate accuracy and predictive values of Doppler ultrasonographic (US) measurement of portal blood velocity (PBV) and splenic pulsatility index (SPI) in diagnosis of clinically relevant acute rejection in patients with clinicobiochemical hepatic dysfunction after orthotopic liver transplantation (OLT).

MATERIALS AND METHODS

Study was approved by the institutional review board, and protocol conformed to ethical guidelines of Declaration of Helsinki. Patient informed consent was obtained. In 27 patients with OLT (23 men, four women; mean age, 48 years; range, 27-64 years), PBV and SPI were measured at Doppler US within 48 hours before or after liver biopsy for clinically suspected acute rejection. Biopsy specimens were assigned scores according to Banff method, and rejection activity index (RAI) was calculated. RAI score of 4 or greater was considered clinically relevant acute rejection. Doppler US parameters were analyzed as absolute values and as percentage point changes with respect to values obtained at last examination before rejection was suspected. Information from two Doppler US parameters was combined; Doppler US composite index was calculated. Statistical tests were conducted to assess accuracy, sensitivity, specificity, and predictive values of Doppler US parameters in diagnosis of graft rejection.

RESULTS

Clinically relevant acute rejection was diagnosed in nine patients. Median time from OLT until histologic diagnosis of acute rejection was 8 days (range, 5-20 days). Rejection was associated with a marked reduction in mean PBV (-43% +/- 5 [standard error of the mean]) and a slight increase in SPI (+12% +/- 16). The calculated Doppler US composite index was strictly related to severity of rejection (P < .001). When applied retrospectively, this index had good accuracy (88%) for prediction of rejection (specificity, 89%; sensitivity, 86%; negative predictive value, 94%).

CONCLUSION

During the first weeks after OLT, a marked decrease in PBV associated with increased SPI supports suspicion of clinically relevant acute rejection.

Orthotopic liver transplants in children: change in hepatic venous Doppler wave pattern as an indicator of acute rejection

PURPOSE

To determine whether a change in hepatic venous flow pattern can be seen during hepatic graft rejection and if it is reversible with treatment.

MATERIALS AND METHODS

Thirty-nine children received 42 liver allografts during a 10-year span. Doppler ultrasonographic (US) recordings of hepatic venous wave patterns were reviewed. Nine children (ten grafts) with continuously monophasic flow were not included in the study. Changes from triphasic to monophasic flow were recorded and correlated with clinical findings in all 30 patients and biopsy findings in 25. Biopsy results were compared with US data recorded within 24 hours of biopsy. Standard statistical tests were conducted to assess value of Doppler US in diagnosis of graft rejection. Significance was assessed with chi(2) statistics.

RESULTS

Of 113 Doppler US recordings in 30 children, 74 showed an episode of change in flow from triphasic to monophasic in 27 patients; biopsy correlation existed for 39 episodes. Thirty-five episodes were due to acute graft rejection (true-positive results). Thirty-nine episodes were due to a variety of pathologic causes (determined with biopsy results for 12 and by clinical means for 27) (false-positive results). Thirty-six assessments were true-negative (US and biopsy results negative for rejection); three were false-negative. When US results were evaluated against clinical and biopsy data, analysis revealed that change to monophasic flow predicted rejection with sensitivity of 92% (35 of 38) and specificity of 48% (36 of 75). Negative predictive value of evidence of persistent triphasic flow was 92% (36 of 39). In the subgroup of US findings with biopsy correlation, specificity increased from 48% (36 of 75) to 75% (36 of 48). It was zero (0 of 27) for the group with clinical correlation only.

CONCLUSION

Change of hepatic venous flow pattern from triphasic to monophasic is sensitive but nonspecific for detection of graft rejection. Evidence of persistent triphasic flow helps eliminate the possibility of graft rejection with a high negative predictive value.