Usage of 64-detector-row spiral computed tomography volumetry in preoperative volume prediction in living donor liver transplantation in children

Platelet recovery correlates parenchymal volume recovery after liver resection

AIM

Platelet count seems to assess liver function and predict liver regeneration, but factors associated with liver regeneration remain unclear. This study analyzed the relationship between platelet recovery and postresection liver regeneration.

METHODS

Data from 343 candidates from 1245 consecutive patients with liver resection of more than Couinaud's segments were analyzed. Patients were divided into a low-platelet-recovery rate (LPRR) group (lowest 25%) or a control group on the basis of the platelet recovery rate on postoperative day (POD)7. Data were matched before analysis to adjust for operation scale. Trends in liver functional recovery were assessed, and liver volume recovery and remnant ischemic area was calculated using computed tomography volumetry. Factors predicting liver regeneration were analyzed.

RESULTS

In 78 matched-pair patients, the all-complications rate (42.3% vs. 26.9%, P = 0.002) and infectious complications rate (21.8% vs. 9.0%, P = 0.027) were significantly higher in the LPRR group than in controls. Trends in liver functional recovery did not differ significantly, whereas significant differences remained for platelet recovery. Parenchyma volume recovery was delayed in the LPRR group from POD7 (84.5% vs. 78.1, P < 0.01) to POD30 (92.5% vs. 85.6, P < 0.01). Platelet recovery rate on POD7 correlated negatively with ischemic liver volume as evaluated on POD2 by computed tomography (r = 0.691). Postoperative ischemic volume on POD2 (5.41 [1.98-11.21], P < 0.001), infectious complications (3.48 [1.44-7.37], P < 0.001), and multiple resection (1.67 [1.10-4.11], P = 0.011) predicted delayed platelet recovery rate on multivariate analysis.

CONCLUSION

Platelet recovery correlated with liver volume recovery and occurrence of complications. Large ischemic area might negatively impact regeneration after liver resection.

Comparison Between Pre-operative Radiologic Findings and the Actual Operative Findings of the Graft in Adult Living Donor Liver Transplantation

BACKGROUND

Computed tomography (CT) volumetry and magnetic resonance cholangiopancreatography (MRCP) are mandatory steps for the evaluation of potential donors in living donor liver transplantation. The aim of this study is to compare the preoperative CT volumetry and biliary orifices of the donor graft to the actual operative findings.

METHODS

Between December 2013 and December 2017, 45 donors (27 men and 18 women) with a mean age of 27.3 years (range, 19-41 years) were evaluated preoperatively by CT volumetry and MRCP at the National Hepatology and Tropical Medicine Research Institute in Cairo, Egypt. Of the donors, 43 out of 45 underwent intraoperative cholangiography before and after bile duct division. The right hepatectomies for all donors, as well as the actual weight and apparent biliary orifices in the graft, were documented.

RESULTS

The mean estimated graft volume (EGV) preoperatively by CT volumetry was 894.9 ± 184.2 mL (range, 480-1687 mL), whereas the actual graft weight (AGW) intraoperatively after washout was 862.6 ± 124.4 g (range, 676-1110 g). The correlation coefficient between the EGV and AGW was significantly linear (Y = 0.96X, r² = 0.72, slope: 0.96, P < .001). The accuracy of the MRCP in preoperative biliary mapping was 76.7% whereas the accuracy of the MRCP in predicting the number of graft biliary orifices was 74.4% compared with the intraoperative cholangiography (IOC), which was 95.3% (P < .001).

CONCLUSION

The weight of the right lobe of the liver graft in living donor liver transplants (LDLTs) can be accurately predicted preoperatively by multiplying the EGV by 0.96. Also, the IOC is an essential technique for LDLT.

Accuracy of preoperative CT liver volumetry in living donor hepatectomy and its clinical implications

Background

An accurate preoperative volumetric assessment of donor liver is essential for successful living donor liver transplant by ensuring adequate remnant and graft recipient weight ratio (GRWR).

Methods

The study cohort consisted of 744 right lobe (RL), 65 left lobe (LL) and 33 left lateral sector (LLS) grafts from July 2010 to January 2014. A semi-automated interactive commercial software called AW Volume share 6 was used for volumetry. Bland Altman plot was used for assessing the agreement between estimated graft weight (EGW) and actual graft weight (AGW).

Results

There was no statistically significant difference between EGW and AGW for RL graft weight (722±134 vs. 717±126 gm; P=0.06). Although Bland Altman graph showed that 95% limits of agreement was more in LL (-164 to +110) than RL (-156 to +147) and LLS grafts (-137 to +239), CT scan significantly overestimated LL graft weight (EGW =460±118 gm vs. AGW =433±102 gm; P=0.003) and underestimated LLS graft weight (EGW =203±48 gm vs. AGW =254±49 gm; P<0.001).

Conclusions

CT volumetry overestimate LL graft and underestimate LLS graft weight. This should be factored in when selecting LL graft by taking higher GRWR.

CT evaluation of living liver donor: Can 100-kVp plus iterative reconstruction protocol provide accurate liver volume and vascular anatomy for liver transplantation with reduced radiation and contrast dose?

We evaluated whether donor computed tomography (CT) with a combined technique of lower tube voltage and iterative reconstruction (IR) can provide sufficient preoperative information for liver transplantation.We retrospectively reviewed CT of 113 liver donor candidates. Dynamic contrast-enhanced CT of the liver was performed on the following protocol: protocol A (n = 70), 120-kVp with filtered back projection (FBP); protocol B (n = 43), 100-kVp with IR. To equalize the background covariates, one-to-one propensity-matched analysis was used. We visually compared the score of the hepatic artery (A-score), portal vein (P-score), and hepatic vein (V-score) of the 2 protocols and quantitatively correlated the graft volume obtained by CT volumetry (graft-CTv) under the 2 protocols with the actual graft weight.In total, 39 protocol-A and protocol-B candidates showed comparable preoperative clinical characteristics with propensity matching. For protocols A and B, the A-score was 3.87 ± 0.73 and 4.51 ± 0.56 (P < .01), the P-score was 4.92 ± 0.27 and 5.0 ± 0.0 (P = .07), and the V-score was 4.23 ± 0.78 and 4.82 ± 0.39 (P < .01), respectively. Correlations between the actual graft weight and graft-CTv of protocols A and B were 0.97 and 0.96, respectively.Liver-donor CT imaging under 100-kVp plus IR protocol provides better visualization for vascular structures than that under 120-kVp plus FBP protocol with comparable accuracy for graft-CTv, while lowering radiation exposure by more than 40% and reducing contrast-medium dose by 20%.

Preoperative evaluation of liver volume in living donor liver transplantation

OBJECTIVE:

The aim of the present study was to retrospectively evaluate the difference between the preoperative estimated volume and the actual intraoperative graft volume determined in donor right hepatectomies and to evaluate the possible effect of age, gender, and body mass index on the difference.

METHODS:

A total of 225 donor hepatectomies performed at the center between 2016 and 2017 were evaluated for the study. Left hepatectomies and left lateral segmentectomies were excluded from the analysis. As a result, 174 donor right hepatectomies were included in the study. Volumetric analysis was performed with dynamic hepatic computed tomography (CT), including non-contrast analysis, followed by non-ionic, contrast-enhanced arterial, portal, and hepatic-phase, thin-slice scanning. Volumetric analysis was performed based on the CT images using automatic volume calculating software.

RESULTS:

The mean preoperatively estimated graft volume was 800±112 g and the mean intraoperatively measured actual graft volume was 750±131 g. There was a statistically significant difference (p=0.003). Age and body mass index had a significant impact on the discrepancy between the predicted and actual graft volume, while gender did not.

CONCLUSION:

A thorough preoperative evaluation of the donor graft volume should be performed in order to prevent donor morbidity and mortality, as well as small-for-size and large-for-size phenomena in the implanted grafts. Physicians working in the field of transplantation should be aware of the fact that a difference of 10% between the predicted and the actual graft volume is usually encountered.

Accuracy of estimation of graft size for living-related liver transplantation: first results of a semi-automated interactive software for CT-volumetry

OBJECTIVES

To evaluate accuracy of estimated graft size for living-related liver transplantation using a semi-automated interactive software for CT-volumetry.

MATERIALS AND METHODS

Sixteen donors for living-related liver transplantation (11 male; mean age: 38.2±9.6 years) underwent contrast-enhanced CT prior to graft removal. CT-volumetry was performed using a semi-automated interactive software (P), and compared with a manual commercial software (TR). For P, liver volumes were provided either with or without vessels. For TR, liver volumes were provided always with vessels. Intraoperative weight served as reference standard. Major study goals included analyses of volumes using absolute numbers, linear regression analyses and inter-observer agreements. Minor study goals included the description of the software workflow: degree of manual correction, speed for completion, and overall intuitiveness using five-point Likert scales: 1--markedly lower/faster/higher for P compared with TR, 2--slightly lower/faster/higher for P compared with TR, 3--identical for P and TR, 4--slightly lower/faster/higher for TR compared with P, and 5--markedly lower/faster/higher for TR compared with P.

RESULTS

Liver segments II/III, II-IV and V-VIII served in 6, 3, and 7 donors as transplanted liver segments. Volumes were 642.9±368.8 ml for TR with vessels, 623.8±349.1 ml for P with vessels, and 605.2±345.8 ml for P without vessels (P<0.01). Regression equations between intraoperative weights and volumes were y = 0.94x+30.1 (R2 = 0.92; P<0.001) for TR with vessels, y = 1.00x+12.0 (R2 = 0.92; P<0.001) for P with vessels, and y = 1.01x+28.0 (R2 = 0.92; P<0.001) for P without vessels. Inter-observer agreement showed a bias of 1.8 ml for TR with vessels, 5.4 ml for P with vessels, and 4.6 ml for P without vessels. For the degree of manual correction, speed for completion and overall intuitiveness, scale values were 2.6±0.8, 2.4±0.5 and 2.

CONCLUSIONS

CT-volumetry performed with P can predict accurately graft size for living-related liver transplantation while improving workflow compared with TR.

Liver volumetry: Is imaging reliable? Personal experience and review of the literature

The amount of the future liver remnant volume is fundamental for hepato-biliary surgery, representing an important potential risk-factor for the development of post-hepatectomy liver failure. Despite this, there is no uniform consensus about the amount of hepatic parenchyma that can be safely resected, nor about the modality that should be chosen for this evaluation. The pre-operative evaluation of hepatic volume, along with a precise identification of vascular and biliar anatomy and variants, are therefore necessary to reduce surgical complications, especially for extensive resections. Some studies have tried to validate imaging methods [ultrasound, computed tomography (CT), magnetic resonance imaging] for the assessment of liver volume, but there is no clear evidence about the most accurate method for this evaluation. Furthermore, this volumetric evaluation seems to have a certain degree of error, tending to overestimate the actual hepatic volume, therefore some conversion factors, which should give a more reliable evaluation of liver volume, have been proposed. It is widespread among non-radiologists the use of independent software for an off-site volumetric analysis, performed on digital imaging and communications in medicine images with their own personal computer, but very few studies have provided a validation of these methods. Moreover, while the pre-transplantation volumetric assessment is fundamental, it remains unclear whether it should be routinely performed in all patients undergoing liver resection. In this editorial the role of imaging in the estimation of liver volume is discussed, providing a review of the most recent literature and a brief personal series of correlations between liver volumes and resection specimens’ weight, in order to assess the precision of the volumetric CT evaluation.

Estimation of the congestion area volume in potential living donor remnant livers

BACKGROUND

Living donor liver transplantation is widely performed in adult patients. One of the problems in this setting is a small-for-size graft, which results in dysfunction and poor prognosis of a transplantation. A right liver graft was devised to overcome this problem; furthermore, inclusion of the middle hepatic vein (MHV) has been suggested to greatly improve recipient outcomes. However, extended right hepatectomy involves a surgical risk for the living donor in terms of congestion of the left paramedian sector. The volume of the venoocclusive region of a living donor liver possibly varies depending on the collateral patterns of veins draining the cranial part of segment 4 (S4).

PATIENTS AND METHODS

We were analyzed the normal livers of 50 patients who underwent triphasic contrast-enhanced multidetector row computed tomography during preoperative and postoperative examinations. The patient pathologies consisted of gastric cancer (n = 25), colon cancer (n = 1), or renal cancer (n = 24). We calculated the volume of the entire liver as well as those of the right graft and left remnant lobes for comparison with the drainage volume of each hepatic vein and its branches.

RESULTS

On the basis of the anatomic venous drainage of the cranial part of S4 (V4sup), we classified hepatic veins as group A (n = 31), the V4sup joined the left hepatic vein or the MHV distal to the vein draining S8 area (MV8), or group B (n = 19), V4sup joined the MHV proximal to MV8. The mean volume of the congested area was 6.9% in group A and 15.9% in group B. The venoocclusive areas in the remnant livers were estimated to be larger in group B (P < .001).

CONCLUSION

The collateral pattern of V4sup and MV8 as well as preoperative volumetric analysis are important for graft selection to decide the line of transection.

Can donor liver left lateral sector weight be predicted from anthropometric variables?

Most of the pediatric LT grafts consist in a LLS. Liver graft size matching is one of the major factors determining a successful outcome. The aim of our study was to assess whether anthropometric parameters can be used to estimate the LLS weight. A total of 122 donors (48F/74M) from two transplantation centers were retrospectively reviewed. Eighteen were living related donors (LRLT) and 104 DDs. The donor age was 28.2 yr (range 15-63). The BW and height were, respectively, 70.1 kg (range 45-111) and 172.7 cm (range 152-197). The WLW (n = 66) was 1462 g (range 921-2340), and the liver-to-BW ratio was 2% (range 1.45-2.8%). The LLS graft weight was 313 g (range: 183-537 g). The ratio between LLS and BW was 0.452% (range 0.27-0.74). The LLS represented 22.3% of the WLW with a large variability (range 15.4-31.3%). None of the developed models (linear, nonlinear, or multiple) was clinically usable. The LLS weight is highly variable and is not predictable using simple anthropometric variables. When available, we propose that ultrasonographic estimation of the liver volume should be performed when a liver splitting is considered.