Can Doppler sonography discern between hemodynamically significant and insignificant portal vein stenosis after adult liver transplantation? AJR Am J Roentgenol. 2010;195:1438-1443. [PMID: 21098207 DOI: 10.2214/ajr.10.4636]

Grading portal vein stenosis following partial hepatectomy by high-frequency ultrasonography: an in vivo study of rats

PURPOSE

To evaluate the diagnostic value of ultrasound in grading portal vein stenosis (PVS) in a rat model of 70% partial hepatectomy (PH).

METHODS

A total of 96 Sprague-Dawley rats were randomly divided into a PH group and PVS groups with mild, moderate, and severe PVS following PH. Hemodynamic parameters were measured using high-frequency ultrasound (5-12 MHz high-frequency linear transducer), including pre-stenotic, stenotic, and post-stenotic portal vein diameters (PVDpre, PVDs, PVDpost); pre-stenotic and stenotic portal vein velocity (PVVpre, PVVs); hepatic artery peak systolic velocity (PSV); end-diastolic velocity; and resistive index. The portal vein diameter ratio (PVDR) and portal vein velocity ratio (PVVR) were calculated using the following formulas: PVDR=PVDpre/PVDs and PVVR=PVVs/PVVpre. The value of these parameters in grading PVS was assessed.

RESULTS

Portal vein hemodynamics showed gradient changes as PVS aggravated. For identifying >50% PVS, PVDs and PVDR were the best parameters, with areas under the curve (AUC) of 0.85 and 0.86, respectively. For identifying >65% PVS, PVDs, PVDR, and PVVR were relatively better, with AUCs of 0.94, 0.85, and 0.88, respectively. The AUC of hepatic artery PSV for identifying >65% PVS was 0.733.

CONCLUSION

High-frequency ultrasonography can be used to grade PVS in rats, with PVDs, PVDR, and PVVR being particularly useful. Hepatic artery PSV may help in predicting >65% PVS. These findings provide valuable information for PVS rat model research and offer an experimental basis for further studies on PVS evaluation in living-donor liver transplantation (LDLT).

CLINICAL SIGNIFICANCE

Ultrasonography serves as a first-line technology for diagnosing PVS following LDLT. However, the grading criteria for PVS severity remain unclear. Investigating the use of ultrasonic hemodynamics in the early diagnosis of PVS and grading stenosis severity is important for early postoperative intervention and improving recipient survival rates.

Ultrasound innovations in abdominal radiology: multiparametic imaging in liver transplantation

PURPOSE

Ultrasound plays a central role in liver transplant evaluation. Acute, subacute, and chronic complications can be readily identified using grayscale and color Doppler ultrasound. Contrast-enhanced ultrasound adds a new dimension to liver transplant evaluation, depicting vascular and parenchymal processes with exquisite detail. In addition, emerging evidence suggests that contrast-enhanced ultrasound may allow for localization of biliary leak in select patients. We aimed to assess the use of multiparametric ultrasound-including grayscale, color and spectral Doppler, and contrast-enhanced ultrasound-in the setting of liver transplantation.

METHODS

A literature review was performed using the MEDLINE bibliographic database through the National Library of Medicine. The following terms were searched and relevant citations assessed: "abdominal ultrasound," "contrast-enhanced ultrasound," "liver transplant," and "ultrasound."

RESULTS

Grayscale and color Doppler ultrasound represent the mainstay imaging modalities for postoperative liver transplant evaluation. The addition of contrast enhancement plays a complementary role and can provide valuable information related to the allograft vasculature, parenchyma, and biliary tree. The appropriate implementation of grayscale, color Doppler, and contrast-enhanced ultrasound can optimize sensitivity, specificity, and accuracy for the detection of liver transplantation complications, including hepatic artery stenosis, biliary leakage, and infection.

CONCLUSION

Multimodal sonographic evaluation is essential to identify postoperative complications in liver transplant recipients. Contrast-enhanced ultrasound may be of value in challenging cases, providing excellent anatomic delineation and reducing the risk of false-positive and false-negative diagnoses. A broad familiarity with appropriate applications of both nonenhanced and contrast-enhanced ultrasound may help radiologists optimize allograft assessment and improve patient outcomes.

Immediate and Late Complications After Liver Transplantation

Other than rejection, hepatic artery and portal vein thrombosis are the most common complications in the immediate postoperative period with hepatic arterial thrombosis more common and more devastating. Hepatic artery stenosis is more common 1 month after transplantation, whereas portal and hepatic vein stenosis is more often seen as a late complication. Ultrasound is the first-line imaging examination to diagnose vascular complications with contrast-enhanced CT useful if ultrasound findings are equivocal. MR cholangiography is often most helpful in diagnosing bile leaks, biliary strictures, and biliary stones.

Virtual Journal Club Beyond the Pandemic: An Enduring and Fluid Educational Forum

OBJECTIVE

Since its inception, journal club has been a cornerstone to the life-long process of medical education. The virtual journal club (VJC), initiated as a robust solution to many educational challenges encountered during COVID-19 pandemic-related distance learning, provides an enduring and fluid forum for multilevel teaching and learning.

MATERIALS AND METHODS

In this manuscript we share our institutions' reasoning and methods to implement a VJC for multi-level learners. A standardized format applicable to all VJC sessions was adopted to ensure reproducibility from presenter to presenter. Sessions were held via video conference platforms. Pedagogy regularly emphasized in undergraduate medical education was adopted. Informal assessment of each session's strengths and areas for improvement was performed.

RESULTS

A total of 30 sessions were held prior to manuscript submission, including discussion of 36 refereed journal articles from March 26, 2020, to April 20, 2021. The virtual journal club was very well received by all participants. The medical students and residents found the information current and engaging. The fellows stated that the journal club strengthened their knowledge base and enhanced communication and teaching skills. The attendings learned from its encouraged frank discussion of differing practice patterns. The format of these sessions offers an ideal setting to teach medical students and residents how to evaluate and employ evidence-based medicine and meets multiple LCME and ACGME requirements.

CONCLUSIONS

This VJC forum allows for development of essential nonclinical skills including lifelong active learning and analysis, peer collaboration, and technology adaptation and usage.

Multimodality Imaging after Liver Transplant: Top 10 Important Complications

Patients who have undergone liver transplant are now regularly seen in day-to-day radiology practice. All surgical techniques for liver transplant require arterial, portal venous, hepatic venous and caval, and biliary anastomoses. This review is focused on the 10 "not to be missed" complications of liver transplant that affect the health and life of the graft and graft recipient. Arterial complications are the most common and devastating. Early hepatic artery thrombosis may be catastrophic because the biliary tree is solely dependent on the hepatic artery after transplant and collateral vessels have not yet formed. In contrast, delayed hepatic artery thrombosis may be more insidious as collateral arteries develop. US findings of delayed hepatic artery thrombosis may be similar to those of hepatic artery stenosis and celiac artery stenosis. Splenic artery steal syndrome is an increasingly recognized cause of graft ischemia. Venous complications are much less common. Hepatic venous and caval complications are notable for their increased incidence in living-donor and pediatric transplants. Biliary complications often result from arterial ischemia. Biliary cast syndrome is a notable example in which ischemic biliary mucosa sloughs into and obstructs the duct lumens. Neoplasms also may occur within the hepatic graft and may be due to recurrent malignancy, posttransplant lymphoproliferative disorder, or metastases. US is the initial imaging modality of choice, particularly in the acute postoperative setting. Further evaluation with contrast-enhanced US, CT, or MRI; catheter angiography; endoscopic retrograde cholangiopancreatography; and/or nuclear medicine studies is performed as needed. An invited commentary by Bhargava is available online. Online supplemental material is available for this article. ^©RSNA, 2022.

Practice variation in the immediate postoperative care of pediatric liver transplant patients: Framework for a national consensus

Advancements in critical care management have led to improvement in pediatric LT outcomes. However, there are no specific guidelines for many aspects of immediate post-LT care. This survey examines practice variations in the immediate postoperative care of pediatric LT patients at a large number of active US centers. This study is a cross-sectional survey of medical directors at PALISI-affiliated PICU in the United States. Centers performing pediatric LT were analyzed. Study measures included PICU practices regarding staffing, composition of the multidisciplinary team, early post-LT graft and patient monitoring, and anticoagulation. Of the thirty-five responding centers, twenty-five had a LT program which accounted for one-half of all US pediatric LTs. For analysis, centers were categorized by volume: high (7), medium (11), and low (7). The majority of PICU teams included an intensivist (80%) and hepatologist (84%). High-volume centers were less likely to have 24-hour in-house attending coverage (29%, compared to 64% (medium) and 100% (low)). High-volume centers were most likely to have pre-printed orders, but least likely to have written PICU management protocols. Most centers utilize routine daily liver ultrasound. Routine prophylactic anticoagulation, and the agent of choice, was variable. There is marked inconsistency in post-LT practice across PALISI centers in regards to team composition and immediate post-LT management. A national US consensus for post-LT PICU practices would facilitate outcomes research and would establish a platform for multicenter studies.

Risk factors for portal vein stenosis in pediatric liver transplantation

OBJECTIVE

To analyze the incidence and risk factors of portal vein stenosis (PVS) in pediatric liver transplantation (LT).

METHODS

This retrospective analysis of 396 cases of pediatric LT (patients aged ≤ 14 years old) was conducted at the Liver Transplantation Center of Beijing Friendship Hospital (China) from June 2013 to December 2017. We collected relevant data and calculated the incidence. We analyzed a total of 23 risk factors for PVS children during the perioperative period.

RESULTS

The incidence of PVS in pediatric LT was 6.6%. The following were identified as risk factors for PVS in pediatric LT: Preoperative portal hypertension was complicated, weight (≤7 kg), recipients of portal vein diameter ≤4 mm, GRWR (≥3.5%), the use of cold preservation vein grafts, anastomosis in the region of superior mesenteric vein and splenic vein and reverse blood flow in the portal vein shown in preoperative ultrasound examination. Recipients of portal vein diameter ≤4 mm and the use cold preservation grafts were independent risks factors for PVS in pediatric LT.

CONCLUSION

For recipients with the risk factors identified in this study, we strongly recommend a strict follow-up and the provision of suitable interventions when indicated.

Ultrasonographic hemodynamics for prediction of poor liver regeneration induced by severe portal vein stenosis in rats

Background

Insufficient portal vein blood flow, such as portal vein stenosis (PVS), plays a significant influence on liver regeneration. Early prediction of poor liver regeneration induced by severe PVS is critical. Ultrasound serves as a first-line imaging technique in diagnosing PVS based on the changes of portal vein hemodynamics. However, there is still no consensus on the criteria for evaluating the degree of PVS. Moreover, which degree of PVS can induce poor liver regeneration still is unclear. Therefore, it is essential to determine the stenosis degree that leads to significantly poor liver regeneration and to evaluate the value of ultrasonographic hemodynamics for predicting poor liver regeneration induced by severe PVS.

Methods

Rats were randomly subjected to sham operation rats group (SOR), PH group (group A), and PVS groups with mild, moderate, or severe stenosis flowing PH (groups B-D). PH group was set up a model of 70% hepatectomy, and PVS groups were produced by different degrees of partial portal vein ligation following PH. In the SOR group and PH group, the portal vein diameter (PVD) and portal vein velocity (PVV) were measured by Ultrasound at preoperative and postoperative 1, 3, 7, and 14 d. In PVS groups, PVD and PVV at the stenotic (PVD_s, PVV_s) and pre-stenotic (PVD_pre, PVV_pre) sites were also detected on 1, 3, 7, and 14 d after surgery, calculating the diameter stenosis ratio (DSR) and accelerating blood flow velocity ratio (AVR). Rats were sacrificed at 1, 3, 7, and 14 d post-surgery, and the expression of proliferating cell nuclear antigen (PCNA) and the liver regeneration rate (LRR) at 14 d were evaluated. The PVV_s, DSR, and AVR in the different groups were analyzed combined with the status of liver regeneration, and receiver operating characteristic (ROC) analysis was also applied to assess the value of PVV_s, DSR, and AVR in diagnosing severe PVS and the resulting poor liver regeneration.

Results

Seventy-two rat models of different degrees of PVS were successfully set up following 70% PH. The stenosis ratios (SRs) of each PVS group were 45.16%±3.44%, 59.21%±3.83%, and 69.56%±2.16%, respectively. Poor liver regeneration appeared to be significant when PVS was greater than 65% (group D), of which the LRR at 14 d was significantly lower compared to PH group (group A) and PVS groups with SR ≤50% (group B) and SR >50-65% (group C), respectively (all P<0.05). Meanwhile, PCNA expression of group D was significantly lower compared to group C at 1 d and groups A-C at 3 d (all P<0.05). Differences were also detected at 3 d between groups A and B and groups A and C (both P<0.05). Among PVS groups, PVV_s accelerated dramatically, with significant differences demonstrated between group D and groups B and C at 1 d, as well as group B and groups C and D at 3 d (all P<0.05). At 1, 3, and 7 d, DSR of groups C and D were significantly higher than that of group A (all P<0.05). At 1 and 3 d, AVR of group D was significantly higher than that of groups B and C (all P<0.05). ROC analysis showed the AUC of PVV_s at 1 d in diagnosing severe PVS was 0.84, while at 3 d, it was unable to differentiate from mild-moderate or severe PVS by PVV_s (P>0.05 vs. AUC =0.50). At 1 and 3 d, the AUC of DSR and AVR in diagnosing severe PVS were all greater than 0.80, comparatively much better in AVR (AUC >0.95). The best cut-off points of AVR at 1 and 3 d were 6.91 and 5.36, with the sensitivity and specificity respectively 100%, 91.67% at 1 d, and 100%, 83.33% at 3 d.

Conclusions

Poor liver regeneration could be significantly induced when PVS was greater than 65%. Ultrasound can well prove the changes of portal vein hemodynamics in different degrees of PVS in rats. The parameters PVV_s could be regarded as a valid index for diagnosing PVS but were not applicable for evaluating the stenosis degree. Comparatively, the parameters DSR and AVR, especially AVR, proved to be useful for differentiating severe PVS (>65%) in the early postoperative period, predicting the resulting poor liver regeneration.

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.

Safety and Tolerance of Donor-Derived Mesenchymal Stem Cells in Pediatric Living-Donor Liver Transplantation: The MYSTEP1 Study

Background

Calcineurin inhibitors (CNI) have significantly improved patient and graft survival in pediatric liver transplantation (pLT). However, CNI toxicity leads to significant morbidity. Moreover, CNIs cannot prevent long-term allograft injury. Mesenchymal stem (stromal) cells (MSC) have potent immunomodulatory properties, which may promote allograft tolerance and ameliorate toxicity of high-dose CNI. The MYSTEP1 trial aims to investigate safety and feasibility of donor-derived MSCs in pLT.

Methods/Design

7 to 10 children undergoing living-donor pLT will be included in this open-label, prospective pilot trial. A dose of 1 × 10⁶ MSCs/kg body weight will be given at two time points: first by intraportal infusion intraoperatively and second by intravenous infusion on postoperative day 2. In addition, participants will receive standard immunosuppressive treatment. Our primary objective is to assess the safety of intraportal and intravenous MSC infusion in pLT recipients. Our secondary objective is to evaluate efficacy of MSC treatment as measured by the individual need for immunosuppression and the incidence of biopsy-proven acute rejection. We will perform detailed immune monitoring to investigate immunomodulatory effects.

Discussion

Our study will provide information on the safety of donor-derived MSCs in pediatric living-donor liver transplantation and their effect on immunomodulation and graft survival.

Correction of extrahepatic portal hypertension in pediatric patient after liver transplantation

Introduction. Liver transplantation is a multi-component and complex type of operative treatment. Patients undergoing such a treatment sometimes are getting various complications. One of these complications is a portal hypertension associated with portal vein stenosis.

Materials and methods. In 6 years after the left lateral section transplantation from living donor in a pediatric patient the signs of portal hypertension were observed. Stenosis of the portal vein was revealed. Due to this fact percutaneous transhepatic correction of portal vein stenosis was performed.

Results. As a result of the correction of portal blood flow in the patient a positive trend was noted. According to the laboratory and instrumental methods of examination the graft had a normal function, portal blood flow was adequate. In order to control the stent patency Doppler ultrasound and MSCT of the abdominal cavity with intravenous bolus contrasting were performed. Due to these examinations the stent function was good, the rate of blood flow in the portal vein due to Doppler data has reached 80 cm/sec, and a decrease of the spleen size was noted.

Conclusion. Diagnosis and timely detection of portal vein stenosis in patients after liver transplantation are very important for the preservation of graft function and for the prevention of portal hypertension. In order to do that, ultrasound Doppler fluorimetry examination needs to be performed to each patient after liver transplantation. In cases of violation of the blood flow in the portal vein CT angiography performance is needed. Percutaneous transhepatic stenting of portal vein is a minimally invasive and highly effective method of correction of portal hypertension. Antiplatelet therapy and platelet aggregation control are the prerequisites for successful stent function.

Clinical application of modern ultrasound techniques after liver transplantation

Liver transplantation has been established as a first-line therapy for a number of indications. Conventional ultrasound and contrast-enhanced ultrasound (CEUS) are methods of choice during the postoperative period as a safe and fast tool to detect potential complications and to enable early intervention if necessary. CEUS increases diagnostic quality and is an appropriate procedure for the examination of vessels and possibly bile ducts. This article presents the state of the art of ultrasound application during the early period after liver transplantation. It addresses common vascular complications and describes the identification of postoperative abnormal findings using ultrasound and CEUS.

Sonographic Evaluation of Post-transplantation Portal Vein Stenosis in Pediatric Living-donor Liver Transplant Recipients With Left-liver Grafts

INTRODUCTION

Portal vein (PV) stenosis is not uncommon in post-transplantation pediatric living-donor liver transplant (PLDLT) recipients. The purpose of this study was to identify specific ultrasound criteria that may be used to detect PV stenosis in PLDLT with left-liver grafts.

PATIENTS AND METHODS

From January 2010 to October 2014, 87 pediatric recipients underwent PLDLT with left lobes or left lateral segments at our hospital. All patients underwent routine liver Doppler ultrasound (DUS) as follow-up protocol. The morphologic narrowing and mean time averaged velocity (TAV) at the PV anastomotic site, change in anastomotic/pre-anastomotic TAV (ΔTAV), and the umbilical portal width were evaluated and analyzed. Ultrasound findings were correlated with computed tomography angiography where PV stenosis was suspected.

RESULTS

In the liver graft follow-up study, 80.4% (70 of 87 patients) of PV anastomosis was well visualized and measured by Doppler ultrasound. The optimal threshold values for TAV and ΔTAV were 49.6 cm/s and 30 cm/s, respectively, for significant PV anastomosis stenosis. In the other 19.5% (17/87), the PV anastomosis could not be identified properly. The PV anastomosis was not always visible with ultrasound; however, the optimal dilated umbilical portion of the PV indicating possible PV anastomosis narrowing threshold was umbilical portal width >1.5 cm.

CONCLUSIONS

Increased anastomotic TAV and ΔTAV are useful features for diagnosing PV stenosis. The identification of a dilated umbilical portion of the left PV helps in detection of PV stenosis in PLDLT recipients especially when the anastomotic narrowed region cannot be visualized.

Vascular complications after adult living donor liver transplantation: Evaluation with ultrasonography

Living donor liver transplantation (LDLT) has been widely used to treat end-stage liver disease with improvement in surgical technology and the application of new immunosuppressants. Vascular complications after liver transplantation remain a major threat to the survival of recipients. LDLT recipients are more likely to develop vascular complications because of their complex vascular reconstruction and the slender vessels. Early diagnosis and treatment are critical for the survival of graft and recipients. As a non-invasive, cost-effective and non-radioactive method with bedside availability, conventional gray-scale and Doppler ultrasonography play important roles in identifying vascular complications in the early postoperative period and during the follow-up. Recently, with the detailed vascular tracing and perfusion visualization, contrast-enhanced ultrasound (CEUS) has significantly improved the diagnosis of postoperative vascular complications. This review focuses on the role of conventional gray-scale ultrasound, Doppler ultrasound and CEUS for early diagnosis of vascular complications after adult LDLT.

Pediatric liver transplant portal vein anastomotic stenosis: correlation between ultrasound and transhepatic portal venography

The objective of this study was to determine which transabdominal ultrasound parameters correlate with portal vein stenosis (PVS) on percutaneous transhepatic portal venography in pediatric liver transplant patients. A retrospective review was performed of percutaneous transhepatic portal venograms performed between 2005 and 2013. The findings were compared to those from ultrasounds performed before venography and at the baseline. Patients were stratified on the basis of the presence of significant PVS (group 1, >50% stenosis; group 2, ≤50% stenosis) on portal venography. Findings were compared to those for age-matched controls. Twenty portal venograms were performed for 12 pediatric patients. Thirteen of the 20 patients (65%) demonstrated significant PVS (>50%). The mean peak anastomotic velocity (PAV) was 253.6±96 cm/s in group 1, 169.7±48 cm/s in group 2, and 51.3±20 cm/s in the control group. PAV (r=0.672, P=0.002) was the only ultrasound variable that correlated with the presence of significant PVS. A receiver operating characteristic curve was generated from PAV and PVS data (area under the curve=0.75, P=0.08). A threshold velocity of 180 cm/s led to a sensitivity of 83% and a specificity of 71% in predicting significant PVS on portal venography. At the baseline, the mean PAV was 155.8±90 cm/s for group 1 and 69.5±33 cm/s for group 2 (P=0.08); for control subjects, it was 78.9±53 cm/s (P=0.06). PAV is the only measured ultrasound parameter that correlates with significant PVS on portal venography in pediatric liver transplant patients. An elevated baseline PAV may increase the risk of developing PVS.

Spleen stiffness measurements by acoustic radiation force impulse imaging after living donor liver transplantation in children: a potential quantitative index for venous complications

BACKGROUND

Living donor liver transplantation in children often results in venous complications, leading to portal hypertension. Spleen stiffness measurements have been recently proposed as a new, noninvasive parameter for portal hypertension in cirrhotic patients.

OBJECTIVE

To evaluate the diagnostic value of spleen stiffness measurements by acoustic radiation force impulse (ARFI) imaging in diagnosing venous complications after pediatric living donor liver transplantation.

MATERIALS AND METHODS

We prospectively enrolled 69 patients after pediatric living donor liver transplantation using a left-side liver allograft. Around the time of the protocol liver biopsy examination, spleen stiffness measurements by ARFI imaging were performed via the left intercostal space at the center of the spleen parenchyma and repeated five times. Imaging examinations around the time of the spleen stiffness measurements were retrospectively reviewed. Regarding venous complications, significant portal and hepatic venous stenosis was defined as >50% stenosis on multiphasic computed tomography.

RESULTS

After post hoc exclusion, 62 patients were studied. Portal and hepatic venous stenosis was identified in three and two patients, respectively. The median spleen stiffness values were 2.70 and 4.00 m/s in patients without and with venous complications, respectively (P < 0.001). Spleen stiffness measurements showed good diagnostic power for venous complications, and the cutoff value was determined as 2.93 m/s, with 100% sensitivity and 78.9% specificity. Spleen stiffness measurements decreased with the relief of venous stenosis resulting from an interventional radiology procedure.

CONCLUSION

Spleen stiffness measurements by ARFI imaging might provide a useful quantitative index for venous complications after pediatric living donor liver transplantation.

UltraFast Doppler ultrasonography for hepatic vessels of liver recipients: preliminary experiences

Purpose:

The purpose of this study was to investigate the value of UltraFast Doppler ultrasonography (US) for evaluating hepatic vessels in liver recipients.

Methods:

Thirty-nine liver Doppler US sessions were conducted in 20 liver recipients. Each session consisted of UltraFast and conventional liver Doppler US in a random order. We compared the velocities and phasicities of the hepatic vessels, duration of each Doppler study, occurrence of technical failures, and differences in clinical decisions.

Results:

The velocities and resistive index values of hepatic vessels showed a strong positive correlation between the two Doppler studies (mean R=0.806; range, 0.710 to 0.924). The phasicities of the hepatic vessels were the same in both Doppler US exams. With respect to the duration of the Doppler US exam, there was no significant difference between the UltraFast (251±99 seconds) and conventional (231±117 seconds) Doppler studies (P=0.306). In five poor breath-holders, in whom the duration of conventional Doppler US was longer, UltraFast Doppler US (272±157 seconds) required a shorter time than conventional Doppler US (381±133 seconds; P=0.005). There was no difference between the two techniques with respect to technical failures and clinical decisions.

Conclusion:

UltraFast Doppler US is clinically equivalent to conventional Doppler US with advantages for poor breath-holders during the post-liver transplantation work-up.

Radiologic assessment of hepatobiliary surgical complications

The complexity of hepatobiliary procedures continues to evolve at a rapid rate, with an increasing number of living donor liver transplants and extensive cancer resections being performed. The associated complications are a significant cause of morbidity and mortality, and are often complex injuries, involving both vascular and biliary structures. In this paper we describe the complications associated with laparoscopic cholecystectomy, liver transplant surgery, and hepatic resection. Focus is on the classical imaging appearances, imaging modality options, and varying management strategies for these injuries, to show how the radiologist's role is vital in ensuring the correct diagnosis is made and the appropriate treatment is instigated.

Clinical course of idiopathic intracranial hypertension with transverse sinus stenosis

OBJECTIVE

Transverse sinus stenosis (TSS) is common in idiopathic intracranial hypertension (IIH), but its effect on the course and outcome of IIH is unknown. We evaluated differences in TSS characteristics between patients with IIH with "good" vs. "poor" clinical courses.

METHODS

All patients with IIH seen in our institution after September 2009 who underwent a high-quality standardized brain magnetic resonance venogram (MRV) were included. Patients were categorized as having a good or poor clinical course based on medical record review. The location and percent of each TSS were determined for each patient, and were correlated to the clinical outcome.

RESULTS

We included 51 patients. Forty-six patients had bilateral TSS. The median average percent stenosis was 56%. Seventy-one percent of patients had stenoses >50%. Thirty-five of the 51 patients (69%) had no final visual field loss. Eight patients (16%) had a clinical course classified as poor. There was no difference in the average percent stenosis between those with good clinical courses vs those with poor courses (62% vs. 56%, p = 0.44). There was no difference in the percent stenosis based on the visual field grade (p = 0.38). CSF opening pressure was not associated with either location or degree of TSS.

CONCLUSION

TSS is common, if not universal, among patients with IIH, and is almost always bilateral. There is no correlation between the degree of TSS and the clinical course, including visual field loss, among patients with IIH, suggesting that clinical features, not the degree of TSS, should be used to determine management in IIH.

Treatment-emergent adverse events after infusion of adherent stem cells: the MiSOT-I score for solid organ transplantation

BACKGROUND

Cellular therapy after organ transplantation is emerging as an intriguing strategy to achieve dose reduction of classical immunosuppressive pharmacotherapy. Here, we introduce a new scoring system to assess treatment-emergent adverse events (TEAEs) of adherent stem cell therapies in the clinical setting of allogeneic liver transplantation (for example, the MiSOT-I trial Eudract CT: 2009-017795-25).

METHODS

The score consists of three independent modalities (set of parameters) that focus on clinically relevant events early after intravenous or intraportal stem cell infusion: pulmonary toxicity, intraportal-infusional toxicity and systemic toxicity. For each modality, values between 0 (no TEAE) and 3 (severe TEAE) were defined. The score was validated retrospectively on a cohort of n=187 recipients of liver allografts not receiving investigational cell therapy between July 2004 and December 2010. These patients represent a control population for further trials. Score values were calculated for days 1, 4, and 10 after liver transplantation.

RESULTS

Grade 3 events were most commonly related to the pulmonary system (3.5% of study cohort on day 4). Almost no systemic-related TEAEs were observed during the study period. The relative frequency of grade 3 events never exceeded 5% over all modalities and time points. A subgroup analysis for grade 3 patients provided no descriptors associated with severe TEAEs.

CONCLUSION

The MiSOT-I score provides an assessment tool to score specific adverse events that may occur after adherent stem cell therapy in the clinical setting of organ transplantation and is thus a helpful tool to conduct a safety study.

Hemodynamics of portal venous stenosis before and after treatment in pediatric liver transplantation: evaluation with Doppler ultrasound

AIM

The aim of this study was to evaluate portal vein stenosis (PVS) in pediatric liver transplantation (PLT) using Doppler ultrasound (DUS) before and after interventional management for hemodynamic changes.

MATERIALS AND METHODS

From 2000 to 2010, we encountered 11 PVS cases among 180 PLT that were evaluated using DUS and computed tomography (CT) angiography (CTA); all underwent portal stenting. DUS was used to monitor portal hemodynamics. For the diagnosis of PVS, we investigated multiple parameters including stenotic size (SS), stenotic ratio (SR) (SR [%]=PRE-SS/PRE [PRE=stenotic size]), portal flow velocity ratio (VR) (VR=VS/PRE [PRE=velocity at prestenotic site; VS=peak velocity at stenotic site]), spleen size, and platelet count.

RESULTS

The incidence of PVS was 5.6% (11/180). The PV was 2.5 mm using DUS and 2.7 mm using CTA. The average SR was 65% fitting the criterion. Low prestenotic portal flow<12 cm/sec and high peak velocity in the stenotic segment (up to 147 cm/sec) were observed in 6 cases. The VR value was high at 7.5:1 and there was splenomegaly with thrombocytopenia. After portal vein stenting, hyperperfusion occurred might after reopening the stenosis: the flow increased to an average of 34 cm/sec and then flow decreased slowly to a stable level 2 weeks later. The size of the spleen decreased from 17 to 12 cm and the thrombocytopenia also improved with platelet counts increasing from 67×10(3) to 178×10(3)/μl at 2 months follow-up. The changes in portal flow, portal vein size, spleen size, and platelet count were significant (P<.05).

CONCLUSION

PVS is diagnosed using DUS by increased intrahepatic PV dilatation, peak flow at the stenotic site, discrepant VR. Early portal stenting showed a better prognosis. DUS is essential and effective for hemodynamic monitoring and management of PVS.

Pre- and postoperative imaging and interventions for the meso-Rex bypass in children and young adults

The meso-Rex bypass is a physiological and anatomical bypass procedure for relief of extrahepatic portal vein obstruction and restoration of mesenteric venous return to the liver. Most patients who are candidates for the bypass are children or young adults with portal hypertension and hypersplenism secondary to cavernous transformation of the portal vein. Most frequently, the bypass utilizes an autologous venous graft to connect the intrahepatic left portal vein to the infrapancreatic superior mesenteric vein (SMV) re-establishing first-pass portal perfusion. We describe the preoperative imaging of the 92 bypass candidates, the surgical anatomy as reflected in postoperative imaging, and the imaging of bypass complications at our institution.Preoperative imaging with US, CT and MR is directed to demonstrate patency and size of the left portal vein and SMV, to define the extent of cavernous transformation and splanchnic collaterals, and to assess for any associated abdominal vascular or solid organ abnormalities. Postoperative imaging is aimed at diagnosing meso-Rex bypass stenosis or occlusion and the interventional management of these complications.

Multimodality imaging of normal hepatic transplant vasculature and graft vascular complications

Orthotopic liver transplantation is an important treatment option for patients with end-stage liver disease. Advances in surgical technique, along with improvements in organ preservation and immunosuppression have improved patient outcomes. Post-operative complications, however, can limit this success. Ultrasound is the primary imaging modality for evaluation of hepatic transplants, providing real-time information about vascular flow in the graft. Graft vascular complications are not uncommon, and their prompt recognition is crucial to allow for timely graft salvage. A multimodality approach including CT angiography, MRI, or conventional angiography may be necessary in cases of complex transplant vascular anatomy or when sonography and Doppler are inconclusive to diagnose the etiologies of these complications. The purpose of this article is to familiarize radiologists with the normal post-transplant vascular anatomy and the imaging appearances of the major vascular complications that may occur within the hepatic artery, portal vein, and venous outflow tract, with an emphasis on ultrasound.