H.-K. Wang

Hepatic Venous Congestion After Living Donor Liver Transplantation: Quantitative Assessment of Liver Stiffness Using Shear Wave Elastography—A Case Report

We report a 49-year-old right lobe liver transplant recipient, who developed a significant anastomotic stenosis of the right hepatic vein shortly thereafter. Shear wave elastography (SWE) was applied to investigate liver stiffness quantitatively. It showed increased stiffness in the anterior compared with the posterior segment of right lobe graft. The stenotic right hepatic venous anastomosis was then managed by angioplasty with stent placement. SWE after angioplasty showed a gradual decrease in stiffness of the anterior segment, which was almost equal to the posterior segment at 2 weeks thereafter. Our experience suggested that SWE may be a noninvasive tool to assess alterations in liver stiffness secondary to hepatic venous congestion after liver transplantation.

Minimization or withdrawal of immunosuppressants in pediatric liver transplant recipients.

BACKGROUNDnWe aimed to minimize the dose of tacrolimus in pediatric patients undergoing liver transplantation prospectively.nnnMETHODSnPediatric liver transplant recipients with stable graft function >1year (transplant at <1year of age), or 2years (transplant at >1year of age) post transplant were screened. After baseline graft biopsy, patients were enrolled into our protocol for elective tacrolimus dose reduction. Patients were assessed by liver function test and protocol biopsy during and after tacrolimus dose reduction.nnnRESULTSnFrom January 2011 to December 2012, 16 patients were recruited, of whom 15 completed follow-up at a mean 40.75±5.98months. Six patients were preliminarily weaned off tacrolimus, and five remained tacrolimus-free for more than 2years. Of the 10 patients who were not weaned off tacrolimus, six experienced seven episodes of clinical rejection. Five patients had a reduction in tacrolimus dosage to an undetectable trough level, another five to a trough level <4ng/ml, including one patient who was off the study. At the last patient visit, all of the patients had normal liver function test results with no graft loss. Three patients had low-grade graft fibrosis. The patients with metabolic liver disease (p=0.039) and who were recruited earlier after transplantation (p=0.028) were more likely to be weaned off tacrolimus.nnnCONCLUSIONnTacrolimus withdrawal is feasible in select pediatric liver transplant recipients, and long-term follow-up for these patients is suggested.

Correlation of histopathologic and dynamic tissue perfusion measurement findings in transplanted kidneys

BackgroundCortical perfusion of the renal transplant can be non-invasively assessed by color Doppler ultrasonography. We performed the Dynamic Tissue Perfusion Measurement (DTPM) of the transplant’s renal cortex using color Doppler ultrasonography (PixelFlux technique), and compared the results with the histopathological findings of transplant biopsies.MethodsNinety-six DTPM studies of the renal transplant’s cortex followed by transplant biopsies were performed in 78 patients. The cortical perfusion data were compared with the parameter of peritubular inflammatory cell accumulation (PTC 0 to 3) based on Banff-classification system.ResultsA significant decrease of cortical perfusion could be demonstrated as the inflammatory cells accumulation in peritubular capillaries increased. Increasing peritubulitis caused a perfusion loss from central to distal layers of 79% in PTC 0, of 85% in PTC 1, of 94% in PTC 2, and of 94% in PTC 3. Furthermore, the perfusion loss due to peritubular inflammation was more prominent in the distal cortical layer. The extent of perfusion decline with increasing peritubulitis (from PTC 0 to PTC 3) was 64% in proximal 20% cortical layer (p20), 63% in proximal 50% cortical layer (p50), increased to 76% in distal 50% cortical layer (d50), and peaked at 90% in the distal 20% cortical layer (d20). For those without peritubulitis (PTC 0), the increase in the the Interstitial Fibrosis/Tubular Atrophy (IF/TA) score was accompanied by a significantly increased cortical perfusion. A Polyomavirus infection was associated with an increased cortical perfusion.ConclusionsOur study demonstrated that the perfusion of the renal transplant is associated with certain pathological changes within the graft. DTPM showed a significant reduction of cortical perfusion in the transplant renal cortex related to peritubular capillary inflammation.

Early Postoperative Spectral Doppler Parameters of Renal Transplants: The Effect of Donor and Recipient Factors

BACKGROUNDnThe objective of this study was to explore the donor and recipient factors related to the spectral Doppler parameters of the transplant kidney in the early posttransplantation period.nnnMETHODSnThis retrospective study included 76 patients who underwent renal transplantation assessed using Doppler ultrasonography (US) on the first postoperative day. We compared spectral Doppler parameters (peak systolic velocity [PSV] and resistive index [RI]) of the segmental artery of the transplant kidney according to the type of renal transplant, level of serum creatinine (SCr) of donor prior to organ donation, and donor/recipient age.nnnRESULTSnRI was significantly higher in deceased-donor kidney transplantation (DDKT) as compared with living-donor kidney transplantation (LDKT; 0.73 ± 0.10 vs 0.66 ± 0.11; P = .007). In the DDKT recipients, multivariate analysis showed donor SCr was the only factor affecting PSV (P = .023), whereas recipient age was the only factor affecting RI (P = .035). In the LDKT recipients, multivariate analysis showed recipient age was the only factor affecting both PSV (P = .009) and RI (P = .018).nnnCONCLUSIONnSpectral Doppler parameters in the early posttransplantation period are related to the type of renal transplant, donor renal function, and recipient age. These factors should be taken into consideration when interpreting the results of spectral Doppler US.

Suppressor of cytokine signaling (SOCS) 1 is down-regulated in renal transplant recipients with rejection.

The role of suppressor of cytokine signaling (SOCS) in maintaining the immunotolerance of renal allograft is unknown. To clarify this, peripheral blood mononuclear cells (PBMCs) from renal transplant patients with or without rejection were analyzed for the expression of SOCS family proteins by cell culture, immunoblot, flowcytometry and quantitative reverse transcription-polymerase chain reaction (qPCR). Patients with renal graft rejection expressed lower levels of SOCS1 while those without rejection showed a higher SOCS1 expression in the PBMC either on stimulation or not. In addition, SOCS1 was constitutively expressed in normal individuals as well as renal transplant patients with graft tolerance while patients with rejection exhibited down-regulation of the SOCS1 but not SOCS3. The qPCR tests and flowcytometric measurements have also showed that the reduction of SOCS1 expression in rejection could be quantitatively evaluated. These results have suggested that down-regulation of SOCS1 may be regarded as a biomarker for early detection of renal allograft rejection.

Comparison of Two Devices for Intraoperative Portal Venous Flow Measurement in Living-Donor Liver Transplantation: Transit Time Ultrasound and Conventional Doppler Ultrasound

BACKGROUNDnIntraoperative portal venous flow measurement provides surgeons with instant guidance for portal flow modulation during living-donor liver transplantation (LDLT). In this study, we compared the agreement of portal flow measurement obtained by 2 devices: transit time ultrasound (TTU) and conventional Doppler ultrasound (CDU).nnnMETHODSnFifty-four recipients of LDLT underwent intraoperative measurement of portal flow after completion of vascular anastomosis of the implanted partial liver graft. Both TTU and CDU were used concurrently. Agreement of TTU and CDU was assessed by intraclass correlation coefficient using a model of 2-way random effects, absolute agreement, and single measurement. A Bland-Altman plot was applied to assess the variability between the 2 devices.nnnRESULTSnThe mean, median, and range of portal venous flow was 1456, 1418, and 117 to 2776 mL/min according to TTU; and 1564, 1566, and 119 to 3216 mL/min according to CDU. The intraclass correlation coefficient of portal venous flow between TTU and CDU was 0.68 (95% confidence interval, 0.51-0.80). The Bland-Altman plots revealed an average variation of 4.8% between TTU and CDU but with a rather wide 95% confidence interval of variation ranging fromxa0-57.7% to 67.4%.nnnCONCLUSIONSnIntraoperative TTU and CDU showed moderate agreement in portal flow measurement. However, a relatively wide range of variation exists between TTU and CDU, indicating that data obtained from the 2 devices may not be interchangeable.

Increased Stiffness of the Remnant Right Lobe Liver After Left Lobectomy or Lateral Segmentectomy in Donors of Living-Donor Liver Transplantation

BACKGROUNDnLiver stiffness is associated with the degree of fibrosis along with other factors. Abrupt change of liver perfusion after hepatectomy is one such factor. In this study, we performed ultrasound elastography to explore the stiffness of the right lobe liver before and after hepatectomy in donors who underwent resection of left lobe or lateral segment of liver.nnnMETHODSnA total of 32 left lobe liver donors (18 male and 14 female; age range, 21-55 years; mean age, 35.1 years; 19 left lobectomy with middle hepatic reserved for graft and 13 lateral segmentectomy with middle hepatic vein reserved in the remnant liver) were included in this study. Liver stiffness was measured by means of ultrasound elastography with the use of acoustic radiation force impulse imaging. Stiffness of the right lobe liver was obtained by means of right intercostal approach.nnnRESULTSnThe stiffness of remnant right lobe liver significantly increased after hepatectomy (1.24 ± 0.18 vs 1.10 ± 0.13 m/s; Pxa0= .001). Donors of left lobe liver showed higher stiffness in the remnant right lobe liver compared with donors of lateral segment (1.30 ± 0.18 vs 1.15 ± 0.14 m/s; Pxa0= .027). There was no significant correlation between the remnant right lobe liver stiffness, postoperative liver function, and flow parameters of hepatic artery and portal vein.nnnCONCLUSIONSnThe stiffness of remnant liver significantly increased after hepatectomy. Furthermore, the stiffness was higher in donors undergoing left lobectomy compared with those undergoing lateral segmentectomy.

Acoustic Radiation Force Impulse Imaging of the Transplant Kidney: Correlation Between Cortical Stiffness and Arterial Resistance in Early Post-transplant Period

BACKGROUNDnAcoustic radiation force impulse (ARFI) imaging is a noninvasive imaging modality for quantitative assessment of tissue stiffness. This study utilized ARFI imaging toxa0assess the stiffness of a transplant renal cortex within the first month after renal transplantation and to explore the correlation between the cortical stiffness and arterial resistance of the transplant kidney.nnnMETHODSnForty renal transplant recipients (male/femalexa0= 26/14; mean age: 45.3 years; deceased donor/living related donorxa0= 27/13) were included in this study. ARFI imaging with virtual touch tissue imaging quantification was applied to assess the stiffness of the transplant renal cortex by using a linear ultrasound transducer. Arterial resistance was acquired by spectral Doppler examination of the main artery and intrarenal arteries of the transplant kidney using a curvilinear ultrasound transducer.nnnRESULTSnThe stiffness of transplant renal cortex was expressed as shear wave velocity (m/s). The mean value of cortical stiffness was 3.19 ± 1.01 m/s (range: 1.55-5.54). The stiffness of transplant renal cortex was positively correlated with the resistance index of the main renal artery (rxa0= 0.55, Pxa0= .001), segmental artery (rxa0= 0.43, Pxa0= .005), and interlobar artery (rxa0= 0.42, Pxa0= .006).nnnCONCLUSIONnThe stiffness of a transplant renal cortex is positively correlated with the arterial resistance of the renal transplant in the early post-transplant period. This result indicates that, in addition to renal fibrosis, the stiffness of the transplant renal cortex is also influenced by the hemodynamics of the transplant kidney.

Enlarging vascular stents after pediatric liver transplantation

BACKGROUNDnEndovascular intervention with stent placement to treat portal vein (PV) and hepatic vein (HV) stenosis after pediatric liver transplantation (LT) is still controversial in small children owing to the potential risk of functional stenosis after growth. The aim of this study is to evaluate the safety and efficacy of stent placement in this population.nnnMETHODSnBetween 2004 and 2016, 6 children (all <3 years) received HV (n = 2) and PV (n = 4) stents placement among 46 pediatric LT patients at our institution. The clinical outcome and patency rate were followed. Morphologic changes of stents were assessed from plain films by a new index: the stent diameter ratio (SDR).nnnRESULTSnThe median age of the patients at LT was 8.9 months. The patency rate was 100% without functional stenosis during a median follow-up period of 65.5 months. The stent growth phenomenon was demonstrated by SDR with significant resolution of hourglass deformity 2 years after stent placement (p for trend <.001).nnnCONCLUSIONnVascular stent placement is a safe and effective method for the management of PV and HV stenosis following pediatric LT because these stents will enlarge as children grow.nnnTYPE OF STUDYnCase Series with no Comparison Group LEVEL OF EVIDENCE: Level IV.