Influence of preoperative portal hypertension and graft size on portal blood flow velocity in recipient after living donor liver transplantation with right-lobe graft

Value of Doppler ultrasonography in predicting clinical outcomes for patients with acute cellular rejection after liver transplantation

PURPOSE

This study investigated the value of Doppler ultrasonography in predicting clinical outcomes after antirejection treatment for patients with acute cellular rejection (ACR) following liver transplantation (LT).

METHODS

This retrospective study included 84 patients who were pathologically diagnosed with ACR and received antirejection treatment within 90 days following LT. Two radiologists searched for abnormal Doppler parameters at ACR diagnosis and within 7 days after antirejection treatment initiation, including portal blood velocity (PBV) <20 cm/s, hepatic artery resistive index <0.5, and a monophasic hepatic vein flow pattern. Interval PBV changes were also evaluated. The frequencies of abnormal Doppler parameters and PBV changes were compared by treatment outcome.

RESULTS

The frequency of abnormal PBV in the early post-treatment phase (PBVearly post-treatment) was significantly higher among poor responders (50.0% [10/20]) than among good responders (7.8% [5/64]) (P<0.001). The sensitivity, specificity, and accuracy of abnormal PBVearly post-treatment as a predictor of poor response to antirejection treatment were 50.0% (10/20), 92.2% (59/64), and 82.1% (69/84), respectively. A decrease (>10%) from the PBV at event (PBVevent) to PBVearly post-treatment was significantly more common among poor responders (50.0% [10/20]) than among good responders (20.3% [13/64]) (P=0.019). The sensitivity, specificity, and accuracy of this PBV decrease in predicting poor treatment response were 50.0% (10/20), 79.7% (51/64), and 72.6% (61/84), respectively.

CONCLUSION

Abnormal PBVearly post-treatment and a decrease between PBVevent and PBVearly post-treatment were significantly associated with poor treatment response in patients with ACR after LT. Consequently, Doppler ultrasonography may be useful for predicting clinical outcomes in these patients.

A Single-Center Experience in Portal Flow Augmentation in Liver Transplantation With Prior Large Spontaneous Splenorenal Shunt

Large portosystemic shunts may cause portal steal syndrome in liver transplantation (LT). Because of the possible devastating consequences of the syndrome, the authors recommend perioperative management of these large shunts. Fourteen adult recipients who underwent portal flow augmentation, including left renal vein ligation (LRVL), renoportal anastomosis (RPA), shunt ligation (SL), and splenic vein ligation (SVL) for large spontaneous splenorenal shunt (SSRS), are included in this study, and the results were analyzed. A total of 13 patients had a large SSRS, and in 1 patient, the large shunt was placed between the superior mesenteric vein and the right renal vein. LDLT was performed in 13 patients. LRVL (n = 5), SVL (n = 6), RPA (n = 2), SL (n = 1) were performed to the patients as graft inflow augmentation. The graft-recipient weight ratios (GRWR) were less than 0.8% in 5 patients (35.7%): 2 had LRVL, and 3 had SVL. Small-for-size syndrome (SFSS) occurred only in these 2 patients with LRVL (GRWR ≤0.8%) and, splenic artery ligation was performed for graft inflow modulation. No mortality or serious complications were reported during follow-up. We consider that in patients with large SSRS and small-for-size grafts, SVL can be performed safely and with satisfactory outcomes.

Indirect Doppler ultrasound abnormalities of significant portal vein stenosis after liver transplantation

PURPOSE

To determine indirect Doppler ultrasound (DUS) abnormalities associated with significant portal vein (PV) stenosis (PVS) in recipients of liver transplantation (LT).

METHODS

This retrospective study was approved by our institutional review board. Between February 2006 and May 2017, 41 LT recipients were diagnosed with significant PVS, defined as having more than 50% narrowing of PV diameter for any reason, including thrombosis or flow disturbance associated with prominent collateral vessels on portal venography. We reviewed the DUS findings of hepatic arteries (HAs) as well as PVs of them, before and after treatment of PVS, and in comparison, with a one-to-one case-matched control. Inter-group comparison of frequency in DUS abnormalities was performed using Chi square (χ²) with Fisher's exact test and McNemar's test. Diagnostic values of each abnormal DUS finding and combinations were also evaluated.

RESULTS

DUS of significant PVS showed "no demonstrable color flow," either at recipient PVs or anastomoses (26.7%), and showed turbulence (66.7%) and hepatofugal portal flow (HFPF; 20.0%) at the graft PVs. HFPF was more frequently observed in those with "no demonstrable color flow" at recipient PVs or anastomoses (p = 0.006). DUS of graft HAs revealed tardus-parvus waveforms (20.9%) and prolonged systolic acceleration times (16.3%), more commonly in the "no demonstrable color flow" group (p = 0.012). These indirect DUS abnormalities disappeared and resolved on follow-up DUS after treatment. In the control group, such Doppler abnormalities were less frequently shown than in the PVS group (p ≤ 0.01, respectively). When one of the portal-blood flow velocity (PFV)-related index abnormalities (such as increased time average velocity [TAV] at anastomosis and TAV ratio between recipient PV and anastomosis) or "no demonstrable color flow" were shown in DUS as well as one of the indirect DUS abnormalities, sensitivity, and specificity was 71.11 and 97.78%, respectively.

CONCLUSION

In addition to PFV-related abnormalities, DUS occasionally shows "no demonstrable color flow" either at recipient PVs or anastomoses, and indirect Doppler abnormalities such as turbulence, HFPF at graft PVs, and abnormal waveforms at graft HAs in LT recipients with significant PVS. The combination of PFV-related abnormalities and indirect DUS abnormalities would be helpful for diagnosis of PVS.

N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein after portosystemic collateral embolization in liver transplantation recipient: what is the clinical significance?

Background An N-butyl-2 cyanoacrylate (NBCA) embolus in the graft portal vein was frequently observed after an intraoperative embolization of portosystemic collaterals performed to prevent portal steal in liver transplant (LT) recipients. The radiological and clinical features of NBCA emboli have not yet been described. Purpose To describe radiological and clinical features of NBCA embolus in graft portal vein after portosystemic collateral embolization in LT recipients. Material and Methods A total of 165 consecutive LT recipients who had undergone intraoperative NBCA embolization of varix were found in single institution's computerized databases of a clinical cohort of LT. Patients were evaluated for NBCA emboli (categorized into major and minor emboli according to location) on first postoperative computed tomography (CT). All electronic medical records and radiologic studies including follow-up was evaluated to determine any radiological and clinical abnormality associated with NBCA embolus. Results NBCA emboli were found in 24% (39/165) of recipients. Although most patients had minor emboli (77%, 30/39) without remarkable ultrasonography (US) abnormalities, seven (78%) of nine recipients with major emboli showed intraluminal echogenic lesions in graft portal vein on grayscale US, and five of them (71%) showed partial portal flow obstruction, although none exhibited any abnormality on contrast-enhanced US. Recipients with NBCA portal emboli showed no significant clinical abnormalities and were discharged safely. NBCA embolus eventually disappeared mostly within six months (82%, 32/39). Conclusion NBCA emboli are frequently observed after portosystemic collateral embolization in LT recipients and are not associated with poor clinical outcome. They may mimic ordinary thromboemboli on US.

Clinically severe portal hypertension: role of multi-detector row CT features in diagnosis

BACKGROUND AND AIM

To explore the CT signs which permit estimation of clinically severe portal hypertension (PH) [≥ 12 of hepatic vein pressure gradient (HVPG)].

METHODS

One-hundred and seven consecutive patients who underwent HVPG measurement in the PH group and 52 controls were included. The diameters of main portal vein (øMPV), superior mesenteric vein (øSMV), splenic vein (øSV), and left gastric vein, øMPV/øSV, øSMV/øSV, as well as estimated spleen volumes were evaluated on the CT scan. The grade of varix and ascites were also evaluated semi-quantitatively. We explored the statistically significant CT features related to severe PH and performed a logistic regression analysis for an estimation model for severe PH.

RESULTS

øMPV/øSV and øSMV/øSV tended to gradually increase as the PH became severer, and the difference between severe and not severe groups was statistically significant (p = 0.015 and 0.038, respectively). According to the regression analysis, øSMV/øSV and the grade of esophageal varix and ascites were finally included as related variables for predicting severe PH. The odds ratio (OR) of øSMV/øSV was 4.596, and large esophageal varix (OR 4.135) and mild (OR 3.051) and large amount of ascites (OR 21.781) were statistically significantly related to severe PH.

CONCLUSION

Changing diameters of portal system, the grades of esophageal varices and ascites on multi-detector row computed tomography might be indicative features for clinically severe PH.

Quantitative portal vein velocity of liver cancer patients with transcatheter arterial chemoembolization on angiography

Objective. We applied optical flow method (OFM) to quantify relative velocities of blood flow using digital subtraction angiography (DSA) in the vascular analysis of hepatocellular carcinoma (HCC) patients who underwent transarterial chemoembolization (TACE) treatment. Methods. A total of 40 HCC patients treated by TACE were analyzed in this study. DSA imaging with a 12-inch field of view, 1024 × 1024 pixels and 4 frames/second was acquired. OFM developed for motion estimation is applied for blood flow estimation. Two acrylic phantoms were built to validate the method. Results. The relationship between the OFM and Doppler measurements was found linear with R² = 0.99 for both straight and curved tube phantoms. Quantitative blood flow distribution images of the portal vein region were presented. After TACE, the minimum, maximum and mean velocities in the portal vein all decreased (P < 0.05). Additionally, the velocity in the portal vein is significantly lower with a higher Child-Pugh score (P < 0.01). Conclusions. The present technique provides add-on quantitative information of flows to DSA and the hemodynamic analysis in relative quantifications of blood flow in portal vein of hepatocellular carcinoma patients using DSA.

Doppler sonography of patients with and without acute cellular rejection after right-lobe living donor liver transplantation

OBJECTIVES

To compare percent interval changes in the portal blood flow velocity (%PBV) and venous pulsatility index (%VPI), as determined by Doppler sonography, in patients with and without acute cellular rejection after right-lobe living donor liver transplantation.

METHODS

Forty-seven patients with biopsy-proven acute cellular rejection underwent Doppler sonography. The control group consisted of 47 age- and sex-matched patients without acute cellular rejection. Doppler spectrograms of the portal vein and right hepatic vein were used to calculate mean peak PBVs and VPIs for the first 3 days after right-lobe living donor liver transplantation, defined as PBV(Baseline) and VPI(Baseline). The PBV and VPI closest in time to biopsy in the patient group or at a matched time in the control group were determined as PBV(Event) and VPI(Event), and %PBV and %VPI values were calculated.

RESULTS

The mean PBV(Baseline) values ± SD in the rejection and control groups were 46.0 ± 21.8 and 44.4 ± 20.5 cm/s, respectively; the PBV(Event) values were 32.2 ± 14.5 and 34.4 ± 17.1 cm/s; and the %PBV values were 19.4% ± 39.9% and 2.2% ± 75.4% (P = .73; P = .38; P = .17, respectively). The VPI(Baseline) values were 0.92 ± 0.34 and 0.93 P = .94; P < .001); and the ± 0.38; the VPI(Event) values were 0.46 ± 0.33 and 0.84 ± 0.44 (%VPI values were 45.5% ± 40.1% and 5.6% ± 47.3%, with a greater than 50% VPI observed more frequently in the rejection than in the control group (61.7% versus 12.8%; P < .001).

CONCLUSIONS

The VPI(Event) was significantly lower and a greater than 50% VPI was significantly more frequent in patients with than without acute cellular rejection after right-lobe living donor liver transplantation.