Living Donor Right Liver Lobes: Preoperative CT Volumetric Measurement for Calculation of Intraoperative Weight and Volume

Evaluation of Liver Volume Estimation Methods in Living Donor Liver Transplant: CT Volumetry vs MeVis, With Comparison of Open and Laparoscopic Surgery

BACKGROUND

Accurately assessing graft volume is crucial for donor and recipient safety in living donor liver transplantation. This can be performed using manual computed tomography volumetry (CTvol) or semiautomated methods (MeVis). We aimed to compare CTvol and MeVis in estimating the actual graft weight during LDLT, and analyse any differences in weight between laparoscopic and open donor hepatectomy.

METHODS

A retrospective study of living donors between 2015 and 2022 with complete imaging data was performed. Graft weights were estimated using (1) CT volumetry and (2) semiautomated MeVis software. The primary outcome was graft weight variance ([Predicted weight-Actual weight]/Predicted weight) × 100. The secondary outcome of interest was whether open or laparoscopic surgery affected graft weight variance.

RESULTS

Of the 33 donors, 52.6% were right liver without middle hepatic vein grafts. Nineteen donors (57.6%) underwent open hepatectomy. Both CTvol (r = 0.70; P < .001) and MeVis (r = 0.85; P < .001) showed strong correlation with actual graft weight. Weight variance using CTvol was -2.9% vs -15.3% (P = .04) for open vs laparoscopic, while the corresponding using MeVis was -0.9% vs -8.5% (P = .11). Actual graft-to-recipient weight ratio predicted by MeVis was similar between open and laparoscopic approaches (-0.01 vs 0.07; P = .12).

CONCLUSIONS

Both CT volumetry and MeVis showed strong correlation between predicted and actual graft weights. Laparoscopic hepatectomy showed greater variability in graft weight estimation using CT volumetry, but MeVis was similar across both open and laparoscopic surgery.

Morphometric traits to estimate brain and liver weight and their ratio for the diagnosis of intrauterine growth restriction in newborn piglets

Intrauterine growth restriction (IUGR) is defined as inadequate foetal growth during gestation. In response to placenta insufficiency, IUGR piglets prioritise brain development as a survival mechanism. This adaptation leads to a higher brain-to-liver weight ratio (BrW/LW) at birth. This study assessed the potential of using morphometric traits to estimate brain (BrW) and liver (LW) weights, enabling non-invasive diagnosis of IUGR in newborn piglets. At birth, body weight (BtW) of individual piglets (n = 144) was recorded. One day (± 1) after birth, BrW and LW were measured with computed tomography (n = 94) or by weighing the organs after natural death or euthanasia (n = 50). Additionally, 20 morphometric traits were captured from images of each piglet and correlated with the BrW and LW. The morphometric traits that showed a r ≥ 0.70 in linear correlation with the BrW or LW were selected. Each selected trait was combined as an independent variable with BtW to develop multiple linear regression models to predict the BrW and LW. Six models were chosen based on the highest adjusted R2 value: three for estimating BrW and three for LW. The dataset was then randomly divided into a training (75% of the data) and a testing (remaining 25%) subsets. Within the training subset, three equations to predict the BrW and three to predict the LW were extrapolated from the six selected models. The equations were then applied to the testing subset. The accuracy of the equations in predicting organ weight was assessed by calculating mean absolute and mean absolute percentage error (MAE and MAPE) between predicted and actual BrW and LW. To predict the BrW/LW, an equation including BtW and the two morphometric traits which better predicted BrW and LW was used. In the testing dataset, the equation combining ear distance and BtW better estimated the BrW. The equation performed with a MAE of 1.95 and a MAPE of 0.06 between the true and estimated weight of the brain. For the liver, the equation combining the abdominal area delimited by a square and BtW displayed the best performance, with a MAE of 9.29 and a MAPE of 0.17 between the true and estimated weight. Finally, the MAE and MAPE between the actual and estimated BrW/LW were 0.14 and 0.17, respectively. These findings suggest that specific morphometric traits can be used to estimate brain and liver weights, facilitating accurate and non-invasive identification of IUGR in newborn piglets.

Is an intraoperative liver function assessment possible? Application of the 13C-methacetin-breath-test during major liver resections - a pilot study

BACKGROUND

As prevention of posthepatectomy-liver-failure is crucial, there is need of dynamic assessment of liver function, even intraoperatively. 13C-methacetin-breath-test estimates the organ's microsomal functional capacity. This is its first intraoperative evaluation in major liver surgery.

METHODS

30 patients planed for resection of ≥3 liver segments, between March-November 2019, were prospectively enrolled in this "single-center", pilot study. Using the 13C-methacetin-breath-test, liver function was assessed four times: preoperatively, intraoperatively before and after resection and postoperatively. The resulted maximum-liver-function-capacity (LiMAx)-values and delta-over-baseline (DOB)-curves were compared, further analyzed and correlated to respective liver volumes.

RESULTS

The intraoperative LiMAx-values before resection were mostly lower than the preoperative ones (-11.3% ± 28%). The intraoperative measurements after resection resulted to mostly higher values than the postoperative ones (42.35% ± 46.19%). Pharmacokinetically, an interference between the two intraoperative tests was observed. There was no strong correlation between residual liver volume and function with a percentual residual-LiMAx mostly lower than the percentual residual volume (-17.7% ± 4.1%).

CONCLUSIONS

Intraoperative application of the 13C-methacetin-breath-test during major liver resections seems to deliver lower values than the standard preoperative test. As multiple intraoperative tests interfere significantly to each other, a single intraoperative measurement is suggested. Multicentric standardized measurements could define the "normal" range for intraoperative measurements and control their predictive value.

Liver volumetric and anatomic assessment in living donor liver transplantation: The role of modern imaging and artificial intelligence

The shortage of deceased donor organs has prompted the development of alternative liver grafts for transplantation. Living-donor liver transplantation (LDLT) has emerged as a viable option, expanding the donor pool and enabling timely transplantation with favorable graft function and improved long-term outcomes. An accurate evaluation of the donor liver's volumetry (LV) and anatomical study is crucial to ensure adequate future liver remnant, graft volume and precise liver resection. Thus, ensuring donor safety and an appropriate graft-to-recipient weight ratio. Manual LV (MLV) using computed tomography has traditionally been considered the gold standard for assessing liver volume. However, the method has been limited by cost, subjectivity, and variability. Automated LV techniques employing advanced segmentation algorithms offer improved reproducibility, reduced variability, and enhanced efficiency compared to manual measurements. However, the accuracy of automated LV requires further investigation. The study provides a comprehensive review of traditional and emerging LV methods, including semi-automated image processing, automated LV techniques, and machine learning-based approaches. Additionally, the study discusses the respective strengths and weaknesses of each of the aforementioned techniques. The use of artificial intelligence (AI) technologies, including machine learning and deep learning, is expected to become a routine part of surgical planning in the near future. The implementation of AI is expected to enable faster and more accurate image study interpretations, improve workflow efficiency, and enhance the safety, speed, and cost-effectiveness of the procedures. Accurate preoperative assessment of the liver plays a crucial role in ensuring safe donor selection and improved outcomes in LDLT. MLV has inherent limitations that have led to the adoption of semi-automated and automated software solutions. Moreover, AI has tremendous potential for LV and segmentation; however, its widespread use is hindered by cost and availability. Therefore, the integration of multiple specialties is necessary to embrace technology and explore its possibilities, ranging from patient counseling to intraoperative decision-making through automation and AI.

Estimation of right lobe graft weight for living donor liver transplantation using deep learning-based fully automatic computed tomographic volumetry

This study aimed at developing a fully automatic technique for right lobe graft weight estimation using deep learning algorithms. The proposed method consists of segmentation of the full liver region from computed tomography (CT) images, classification of the entire liver region into the right and left lobes, and estimation of the right lobe graft weight from the CT-measured right lobe graft volume using a volume-to-weight conversion formula. The first two steps were performed with a transformer-based deep learning model. To train and evaluate the model, a total of 248 CT datasets (188 for training, 40 for validation, and 20 for testing and clinical evaluation) were used. The Dice similarity coefficient (DSC), mean surface distance (MSD), and the 95th percentile Hausdorff distance (HD95) were used for evaluating the segmentation accuracy of the full liver region and the right liver lobe. The correlation coefficient (CC), percentage error (PE), and percentage absolute error (PAE) were used for the clinical evaluation of the estimated right lobe graft weight. The proposed method achieved high accuracy in segmentation for DSC, MSD, and HD95 (95.9% ± 1.0%, 1.2 ± 0.4 mm, and 5.2 ± 1.9 mm for the entire liver region; 92.4% ± 2.7%, 2.0 ± 0.7 mm, and 8.8 ± 2.9 mm for the right lobe) and in clinical evaluation for CC, PE, and PAE (0.859, - 1.8% ± 9.6%, and 8.6% ± 4.7%). For the right lobe graft weight estimation, the present study underestimated the graft weight by - 1.8% on average. A mean difference of - 21.3 g (95% confidence interval: - 55.7 to 13.1, p = 0.211) between the estimated graft weight and the actual graft weight was achieved in this study. The proposed method is effective for clinical application.

CT volume analysis in living donor liver transplantation: accuracy of three different approaches

OBJECTIVES

The aim of this retrospective study is to compare and evaluate accuracy of three different approaches of liver volume quantification in living donor transplantations.

METHODS

This is a single-center, retrospective study of 60 donors. The total and right lobe liver volumes were analyzed in the portal-venous phase by two independent radiologists who estimated the volumes using manual, semi-automated and automated segmentation methods. The measured right lobe liver volume was compared to the real weight of the graft after back-table examinations.

RESULTS

The mean estimated overall liver volume was 1164.4 ± 137.0 mL for manual, 1277.4 ± 190.4 mL for semi-automated and 1240.1 ± 108.5 mL for automated segmentation. The mean estimated right lobe volume was 762.0 ± 122.4 mL for manual, 792.9 ± 139.9 mL for semi-automated and 765.4 ± 132.7 mL for automated segmentation. The mean graft weight was 711.2 ± 142.9 g. The manual method better correlated with the graft weight (r = 0.730) in comparison with the semi-automated (r = 0.685) and the automated (r = 0.699) methods (p < 0.001). The mean error ratio in volume estimation by each application was 12.7 ± 16.6% for manual, 17.1 ± 17.3% for semi-automated, 14.7 ± 16.8% for automated methods. There was a statistically significant difference between the mean error ratio of the manual and the semi-automated segmentations (p = 0.017), and no statistically significant difference between the manual and the automated applications (p = 0.199).

CONCLUSION

Volume analysis application better correlates with graft weight, but there is no obvious difference between correlation coefficients of all three methods. All three modalities had an error ratio, of which the semi-automated method showed the highest value.

CRITICAL RELEVANCE STATEMENT

Volume analysis application was more accurate, but there is no drastic difference between correlation coefficients of all three methods.

Machine learning improves the accuracy of graft weight prediction in living donor liver transplantation

Precise graft weight (GW) estimation is essential for planning living donor liver transplantation to select grafts of adequate size for the recipient. This study aimed to investigate whether a machine-learning model can improve the accuracy of GW estimation. Data from 872 consecutive living donors of a left lateral sector, left lobe, or right lobe to adults or children for living-related liver transplantation were collected from January 2011 to December 2019. Supervised machine-learning models were trained (80% of observations) to predict GW using the following information: donor's age, sex, height, weight, and body mass index; graft type (left, right, or left lateral lobe); computed tomography estimated graft volume and total liver volume. Model performance was measured in a random independent set (20% of observations) and in an external validation cohort using the mean absolute error (MAE) and the mean absolute percentage error and compared with methods currently available for GW estimation. The best-performing machine-learning model showed an MAE value of 50 ± 62 g in predicting GW, with a mean error of 10.3%. These errors were significantly lower than those observed with alternative methods. In addition, 62% of predictions had errors <10%, whereas errors >15% were observed in only 18.4% of the cases compared with the 34.6% of the predictions obtained with the best alternative method ( p  < 0.001). The machine-learning model is made available as a web application ( http://graftweight.shinyapps.io/prediction ). Machine learning can improve the precision of GW estimation compared with currently available methods by reducing the frequency of significant errors. The coupling of anthropometric variables to the preoperatively estimated graft volume seems necessary to improve the accuracy of GW estimation.

Accuracy and Efficiency of Right-Lobe Graft Weight Estimation Using Deep-Learning-Assisted CT Volumetry for Living-Donor Liver Transplantation

CT volumetry (CTV) has been widely used for pre-operative graft weight (GW) estimation in living-donor liver transplantation (LDLT), and the use of a deep-learning algorithm (DLA) may further improve its efficiency. However, its accuracy has not been well determined. To evaluate the efficiency and accuracy of DLA-assisted CTV in GW estimation, we performed a retrospective study including 581 consecutive LDLT donors who donated a right-lobe graft. Right-lobe graft volume (GV) was measured on CT using the software implemented with the DLA for automated liver segmentation. In the development group (n = 207), a volume-to-weight conversion formula was constructed by linear regression analysis between the CTV-measured GV and the intraoperative GW. In the validation group (n = 374), the agreement between the estimated and measured GWs was assessed using the Bland–Altman 95% limit-of-agreement (LOA). The mean process time for GV measurement was 1.8 ± 0.6 min (range, 1.3–8.0 min). In the validation group, the GW was estimated using the volume-to-weight conversion formula (estimated GW [g] = 206.3 + 0.653 × CTV-measured GV [mL]), and the Bland–Altman 95% LOA between the estimated and measured GWs was −1.7% ± 17.1%. The DLA-assisted CT volumetry allows for time-efficient and accurate estimation of GW in LDLT.

A simplified CT-volumetry method for the canine liver

Computed tomographic (CT) liver volumetry using the slice addition technique is an accurate, but a time-consuming method. Commonly used DICOM-viewing software only allows contouring of one area per image, which can be troublesome in the transverse plane as different lobes are separated. In this prospective, experimental, methods comparison study, we aimed to determine if hepatic contouring using sagittal reformatting and a reduced number of images would yield accurate results. Computed tomographic studies were performed in five canine cadavers and reviewed using sagittal reformatting. For each dog, the number of images that included the liver was used to create four stacks with progressively fewer images in which the liver would be contoured, each with the following median number of images: A: 60, B: 31, C: 16, and D: 9. Liver volume was calculated by three observers using the different stacks of images. After CT examination, the cadavers were dissected, the liver was removed, and its volume was determined by water displacement. Single score intraclass correlation coefficient was calculated to assess interobserver agreement. Kruskal-Wallis test was used to compare water displacement and CT-based volumes. There was excellent agreement between observers (intraclass correlation coefficient = 0.957; 95% confidence interval, 0.908-0.982, P < 0.0001). No significant difference was found between the volumes obtained by CT-volumetry using each of the stacks and the volumes obtained by water displacement. Using sagittally reformatted images and hepatic contouring in as few as nine images can be an accurate and simple method for CT-volumetry of the canine liver.

Hepatic volume profiles in potential living liver donors with anomalous right-sided ligamentum teres

PURPOSE

In living liver donors with rare anatomical anomaly of right-sided ligamentum teres (RSLT), right or left hemiliver procurement is commonly contraindicated. The purpose of this study was to evaluate the hepatic volume profiles in potential donors with RSLT using semi-automated CT volumetry (CTV).

METHODS

Among 5535 potential donor candidates in our institution between April 2003 and May 2019, 23 cases of RSLT (0.4%) were included. Proportional liver volumes were measured using semi-automated CTV and compared with those of manual volumetry and intraoperative graft weights (seven surgical cases).

RESULTS

The mean percentage volume of the right posterior section was significantly larger than that of the left hemiliver (38.5 ± 8.4% vs. 23.3 ± 5.7%, P < 0.001). Particularly in independent right lateral type, the mean percentage volume of the right posterior section was about two times larger to that of the left hemiliver (41.5% ± 6.5% vs. 21.9% ± 4.4%, P < 0.001), whereas the volume proportions of these two parts were similar between the two parts in bifurcation and trifurcation types (P = 0.810 and 0.979, respectively). Semi-automated CTV of corresponding whole liver, right posterior section, right anterior section, and left hemiliver showed strong correlations with manual CTV (r = 0.989-0.998; P < 0.001). For the seven surgical cases, the graft weights estimated by semi-automated CTV showed a significant correlation with intraoperative graft weights (r = 0.972; P < 0.001).

CONCLUSION

In independent right lateral type of RSLT, the right posterior section tends to be significantly larger than left hemiliver, and may be an alternative option for graft in potential living liver donors with this rare anatomical anomaly.

Impact of Graft Weight Change During Perfusion on Hepatocellular Carcinoma Recurrence After Living Donor Liver Transplantation

BACKGROUNDS

Inadequate liver volume and weight is a major source of morbidity and mortality after adult living donor liver transplantation (LDLT). The purpose of our study was to investigate HCC recurrence, graft failure, and patient survival according to change in right liver graft weight after histidine-tryptophan-ketoglutarate (HTK) solution perfusion in LDLT.

METHODS

Two hundred twenty-eight patients underwent LDLT between 2013 and 2017. We calculated the change in graft weight by subtracting pre-perfusion graft weight from post-perfusion graft weight. Patients with increased graft weight were defined as the positive group, and patients with decreased graft weight were defined as the negative group.

RESULTS

After excluding patients who did not meet study criteria, 148 patients underwent right or extended right hepatectomy. The negative group included 89 patients (60.1%), and the positive group included 59 patients (39.9%). Median graft weight change was -28 g (range; -132-0 g) in the negative group and 21 g (range; 1-63 g) in the positive group (P<0.001). Median hospitalization time was longer for the positive group than the negative group (27 days vs. 23 days; P=0.048). There were no statistical differences in tumor characteristics, postoperative complications, early allograft dysfunction, or acute rejection between the two groups. Disease-free survival, death-censored graft survival, and patient survival were lower in the positive group than the negative group. Additionally, the positive group showed strong association with HCC recurrence, death-censored graft survival, and patient survival in multivariate analysis.

CONCLUSION

This study suggests that positive graft weight change during HTK solution perfusion indicates poor prognosis in LDLT.

A Validation Study of Liver Volumetry Estimation by a Semiautomated Software in Patients Undergoing Hepatic Resections

Purpose The purpose of this study was to validate the use of a semiautomated software for liver volumetry preoperatively by comparing it with the volume of resected specimen in patients undergoing hepatic resections.

Materials and Methods This is a single-center retrospective study of patients who underwent estimation of future liver remnant (FLR) using Myrian XP-Liver which is a semiautomated software for hepatectomy. The estimated resection volume, which is the sum of volume of normal liver to be resected and tumor volume, was compared with actual specimen weight to calculate the accuracy of the software. The statistical analysis was performed with SPSS software version 24.

Results Data on FLR estimation using the semiautomated software was available for 200 out of 388 patients who underwent formal hepatic resections. The median resected volume of surgical specimen was 650 mL (interquartile range [IQR] 364–950), while the median estimated volume using the Myrian software was 617 mL (IQR 362–979). There was significant correlation between estimated resection volume calculated using the semiautomated method and actual specimen weight (p-value < 0.0001) with the Spearman’s correlation value of 0.956.

Conclusion The estimated volume of liver to be resected as calculated by the semiautomated software was accurate and correlated significantly with the volume of resected specimen, and hence, the estimation of FLR volume may likely correlate with the true postoperative residual liver volume. In addition, the software-based liver segmentation, FLR estimation, and color-coded three-dimensional images provide a clear road map to the surgeon to facilitate safe resection.

What is a precise anatomic resection of the liver? Proposal of a new evaluation method in the era of fluorescence navigation surgery

BACKGROUND/PURPOSE

Indocyanine green (ICG) fluorescence navigation has been adapted for anatomic liver resection (AR) but an objective method for evaluation of its validity is required. This pilot study aimed to propose a new method to evaluate the accuracy of parenchymal division along the plane between hepatic segments and estimate the real-time navigation efficacy for AR by the Medical Imaging Projection System (MIPS), which continuously demonstrates the transection plane using projection mapping with ICG fluorescence.

METHODS

Ten patients who underwent open AR using liver segmentation with ICG fluorescence technique between August 2016 and July 2019 were included: six patients under MIPS guidance (MIPS group), while four using only conventional ICG fluorescence technique before parenchymal resection (non-MIPS group). Densitometry of the captured fluorescence image was performed to evaluate the fluorescence area ratio of each transection plane. The accurate fluorescence area ratio was calculated by subtracting the fluorescence area rate on the resected side from that on the remnant side.

RESULTS

The accurate fluorescence area ratio of the MIPS group and the non-MIPS group was 23.0 ± 12.6% and 5.6 ± 9.5%, respectively (P = .038).

CONCLUSIONS

Based on the results of our new method, real-time navigation using the MIPS may facilitate performing AR along the plane between hepatic segments.

Reproducibility and reliability of computed tomography volumetry in estimation of the right-lobe graft weight in adult-to-adult living donor liver transplantation: Cantlie's line vs portal vein territorialization

BACKGROUND/PURPOSE

In living-donor liver transplantation (LDLT), liver volume assessment is a mandatory step in determining donor appropriateness. This study aimed to compare reliability and reproducibility between two major methods to define virtual hepatectomy plane, based on Cantlie's line (CTV-Cantlie) and portal vein territorialization (CTV-PVT) for right-lobe graft weight estimation in LDLT.

METHODS

A total of 188 donors who underwent preoperative CT scans were included. The liver was divided into right and left lobes using CTV-Cantlie and CTV-PTV measurements by two readers. Intraclass correlation coefficient (ICC) was used to determine interreader variability of hepatic weight measured using each CTV method. Intraoperative graft weight (IOW) was used as reference standard of right-lobe graft weight. Pearson correlation test was performed to determine correlation coefficients between presumed graft weight by each CTV method and IOW.

RESULTS

Intraclass correlation coefficients for total liver weight were roughly equivalent between the two CTV methods (CTV-Cantlie: 0.965 [95% CI, 0.954-0.974], CTV-PVT: 0.977 [0.970-0.983]). However, ICCs of right-and left-lobe weights between two readers were higher with CTV-PVT (0.997 and 0.850) than with CTV-Cantlie (0.829 and 0.668). The IOW was 716.0 ± 162.0 g. Correlation coefficients between presumed graft weight by CTV-Cantlie or CTV-PVT and IOW were 0.722 and 0.807, respectively (both P < .001).

CONCLUSIONS

For estimation of the right-lobe graft weight in LDLT, CTV-PVT may provide higher reliability and reproducibility than CTV-Cantlie.

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.

Estimation of the Right Posterior Section Volume in Live Liver Donors: Semiautomated CT Volumetry Using Portal Vein Segmentation

RATIONALE AND OBJECTIVES

To determine the accuracy of semiautomated CT volumetry using portal vein (PV) segmentation to estimate volume of the right posterior section (RPS) graft compared to intraoperative measured weight (W) in live liver donors.

MATERIALS AND METHODS

Among 23 donors who donated RPS grafts for liver transplantation in our institution from April 2003 to August 2016, 17 donors with CT scans within 3 months of liver procurement and PV anatomy of type I-III were included. RPS volumes were retrospectively evaluated by semiautomated CT volumetry (RPSV_CTV) and by measurement of standard liver volume (SLV) and PV area ratio (RPSV_SLV). RPS volumes were compared to W for correlation coefficients, (absolute) difference, and (absolute) percentage deviation. Linear fitting was performed to identify the method that yielded the greatest correlation with W.

RESULTS

Mean values of RPSV_CTV, RPSV_SLV, and W were 503.4 ± 97.8 mL (346.6-686.0), 516.54 ± 146.20 (274.06-776.32), and 518.8 ± 122.4 (370.0-789.0), respectively. RPSV_CTV was strongly correlated with W (r = 0.9414; p < 0.0001), whereas RPSV_SLV was only moderately did (r = 0.5899; p = 0.0127). RPSV_CTV showed a significantly smaller absolute difference (35.20 ± 30.82 vs. 104.79 ± 60.27, p = 0.004) and absolute percentage deviation (6.61 ± 4.90 vs. 19.92 ± 10.37, p < 0.0001) from W. Equation correlating RPSV_CTV and W was W = -74.7191 + 1.1791 RPSV_CTV (R² = 0.8862; p < 0.001).

CONCLUSION

RPSV_CTV yields smaller absolute difference than RPSV_SLV for estimating intraoperative measured weight of RPS in live liver donors. Semiautomated CT volumetry using PV segmentation is feasible for the estimation of the volume of the RPS of the liver, and RPSV_CTV was strongly correlated with W (r = 0.9414; p < 0.0001).

Three-Dimensional Volumetric Assessment of Graft Volume in Living Donor Liver Transplantation: Does It Minimise Errors of Estimation?

BACKGROUND

Accurate volumetric assessment of graft and remnant liver is essential in living donor liver transplantation (LDLT) for optimal clinical outcome in both donors and recipients. Recently, three-dimensional (3D) volumetry is proposed over conventional computed tomography (CT) volumetry to minimise errors. The aim of this study is to assess the correlation of estimated graft volume (EGV) by both the methods with actual graft weight (AGW).

METHODS

One hundred fifty-four consecutive donors were enrolled prospectively. Conventional CT volumetry (semiautomatic) and 3D volumetry were performed using Myrian software. Total liver volume (TLV), EGV, and remnant liver volume (RLV) were assessed using both methods and correlated with intraoperatively measured AGW as the reference standard. Error of estimation was calculated accordingly.

RESULTS

One hundred eighteen donors underwent right hepatectomy excluding middle hepatic vein (MHV), twenty-nine donors had left hepatectomy including MHV and six donors underwent left lateral sectionectomy. The median EGV on CT and 3D volumetry was 628.5 ml (140-1300) and 634.5 ml (156-1349), respectively. The median AGW was 647 gm (200-1004). Both CT and 3D volumetry showed strong correlation with AGW (correlation coefficients: 0.834 and 0.856, respectively). Linear correlation is as follows: (a) AGW = 99.75 + 0.818 × EGV (CT) and (b) AGW = 96.03 + 0.835 × EGV (3D). The mean percentage error for CT and 3D volumetry was 14.2 ± 12.5% and 12.2 ± 11.8%, respectively. The overall accuracy of estimation of EGV improved using 3D software (P=0.015). For the subgroup of types of graft, the difference did not reach statistical significance (P=0.062, 0.214 and 0.463 for right, left and left lateral grafts, respectively).

CONCLUSION

Both conventional CT and 3D volumetric methods strongly correlate with AGW in donors of LDLT, whereas overall accuracy of estimation of graft weight improved marginally by 3D volumetry.

Two-dimensional ultrasound: can it replace computed tomography in liver volume assessment?

Background

Liver volume estimation is considered as an integral part in preoperative evaluation in patients undergoing liver transplantation; computed tomography and magnetic resonance imaging are considered the gold standard methods for liver volume estimation, and both are reliable and valid in determination of liver volume via manual and semi-automated methods. Reliable and accurate set of three simple measurement planes using two-dimensional ultrasound for volumetric assessment of liver was determined, and predictive equation using these three simple measurements was performed, which is simple to perform and easy to calculate, in order to evaluate liver volume and validate these measurements against CT images. Our aim in this study was to evaluate the efficacy and validity of two-dimensional ultrasound in liver volume estimation compared to CT volumetry as a gold standard.

Results

A strong linear positive correlation with no statistical significant difference was found between 2D US and semi-automated CT volumetric, and result was r = 0.7402 and p > 0.05, with an average liver volume of 1572.10 (± 326.43) cm3 and 1559.30 (± 381.02) cm3 respectively.

No statistically significant difference was found also between the two modalities in different age groups and different sexes.

Conclusion

Simple linear two-dimensional ultrasound could be considered an efficient, accurate, and trustable tool for liver volume measurement in clinical practice.

Quantitative and qualitative analysis of bone flap resorption in patients undergoing cranioplasty after decompressive craniectomy

OBJECTIVE: Autologous bone cranioplasty after decompressive craniectomy entails a notable burden of difficult postoperative complications, such as infection and bone flap resorption (BFR), leading to mechanical failure. The prevalence and significance of asymptomatic BFR is currently unclear. The aim of this study was to radiologically monitor the long-term bone flap survival and bone quality change in patients undergoing autologous cranioplasty. METHODS: The authors identified all 45 patients who underwent autologous cranioplasty at Oulu University Hospital, Finland, between January 2004 and December 2014. Using perioperative and follow-up CT scans, the volumes and radiodensities of the intact bone flap prior to surgery and at follow-up were calculated. Relative changes in bone flap volume and radiodensity were then determined to assess cranioplasty survival. Sufficient CT scans were obtainable from 41 (91.1%) of the 45 patients. RESULTS: The 41 patients were followed up for a median duration of 3.79 years (25th and 75th percentiles = 1.55 and 6.66). Thirty-seven (90.2%) of the 41 patients had some degree of BFR and 13 (31.7%) had a remaining bone flap volume of less than 80%. Patients younger than 30 years of age had a mean decrease of 15.8% in bone flap volume compared with the rest of the cohort. Bone flap volume was not found to decrease linearly with the passing of time, however. The effects of lifestyle factors and comorbidities on BFR were nonsignificant. CONCLUSIONS: In this study BFR was a very common phenomenon, occurring at least to some degree in 90% of the patients. Decreases in bone volume were especially prominent in patients younger than 30 years of age. Because the progression of resorption during follow-up was nonlinear, routine follow-up CT scans appear unnecessary in monitoring the progression of BFR; instead, clinical follow-up with mechanical stability assessment is advised. Partial resorption is most likely a normal physiological phenomenon during the bone revitalization process.

Use of Computed Tomography Volumetry to Assess Liver Weight in Patients With Cirrhosis During Evaluation Before Living-Donor Liver Transplant

OBJECTIVES

Computed tomography liver volumetry has been widely used to detect total and segmental liver volume in living-donor liver transplantation. However, use of this technique to evaluate the cirrhotic liver remains unclear. In this study, we evaluated the accuracy of freehand computed tomography volumetry to assess total liver volume by comparing weights of total hepatectomy specimens in patients with cirrhosis. For our analyses, we considered the density of a cirrhotic liver to be 1.1 kg/L.

MATERIALS AND METHODS

Liver volume was measured using a freehand computed tomography technique in 52 patients with cirrhosis from different causes and who had no solid lesions before transplant. Measurements were made with a 16-slice multidetector computed tomography scanner (Siemens Somatom Sensation 16, Erlangen, Germany). For volumetric measurements, 10-mm-thick slices with 10-mm reconstruction intervals were preferred. Total hepatectomy weights of explant livers and computed tomography volumetry data were compared.

RESULTS

We excluded 3 cirrhotic patients with Budd-Chiari syndrome due to wide variations in scatterplot results. In the 49 patients included in the final analyses, average estimated liver volume by computed tomography was 721 ± 398 mL and actual cirrhotic liver weight was 727.8 ± 415 g. No significant differences were shown between these measurements. A simple regression analysis used to analyze correlations between estimated liver volume by computed tomography and real cirrhotic liver weight showed correlation of 0.957 (P < .001). When computed tomography liver volumetry as the independent variable and cirrhotic liver weight as dependent variable were considered, regression analyses showed R2 = 0.915.

CONCLUSIONS

Freehand computed tomography liver volumetry can be confidently used to evaluate liver volume in cirrhotic liver patients similar to use of this technique to estimate actual weights in normal livers. This technique can also be valuable during pretransplant and liver resection evaluations to ensure a more successful outcome.

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.

PREOPERATIVE COMPUTED TOMOGRAPHY VOLUMETRY AND GRAFT WEIGHT ESTIMATION IN ADULT LIVING DONOR LIVER TRANSPLANTATION

Background:

Computed tomography volumetry (CTV) is a useful tool for predicting graft weights (GW) for living donor liver transplantation (LDLT). Few studies have examined the correlation between CTV and GW in normal liver parenchyma.

Aim:

To analyze the correlation between CTV and GW in an adult LDLT population and provide a systematic review of the existing mathematical models to calculate partial liver graft weight.

Methods:

Between January 2009 and January 2013, 28 consecutive donors undergoing right hepatectomy for LDLT were retrospectively reviewed. All grafts were perfused with HTK solution. Estimated graft volume was estimated by CTV and these values were compared to the actual graft weight, which was measured after liver harvesting and perfusion.

Results:

Median actual GW was 782.5 g, averaged 791.43±136 g and ranged from 520-1185 g. Median estimated graft volume was 927.5 ml, averaged 944.86±200.74 ml and ranged from 600-1477 ml. Linear regression of estimated graft volume and actual GW was significantly linear (GW=0.82 estimated graft volume, r²=0.98, slope=0.47, standard deviation of 0.024 and p<0.0001). Spearman Linear correlation was 0.65 with 95% CI of 0.45 - 0.99 (p<0.0001).

Conclusion:

The one-to-one rule did not applied in patients with normal liver parenchyma. A better estimation of graft weight could be reached by multiplying estimated graft volume by 0.82.

Quantification of Hepatic Lipid Using 7.0T Proton Magnetic Resonance Spectroscopy and Computed Tomography in Mild Alcoholic Steatotic Mice

Background:

In vivo proton magnetic resonance spectroscopy (¹H MRS) has been used to semi-quantify hepatic lipids in preclinical and clinical studies of fatty liver disease. Quantifying absolute amount of liver lipids utilizing ¹H MRS and computerized tomography (CT) is essential to accurately interpret hepatic steatosis.

Purpose:

To establish reliable parameters to convert relative hepatic lipid levels obtained by 1H-MRS and liver volumes by CT to the absolute amount of liver lipids in a mild hepatic steatosis, and to determinate the correlation between these absolute liver lipids with liver triglyceride (TG) and cholesterol (Chol) measured by biochemistry assays.

Methods:

Mild steatosis was induced in mice by a 3 week ethanol diet containing standard lipids. Evaporated liver water was measured after baking liver tissues and volume of liver was measured using water displacement. 1H MRS semiquantitation of hepatic lipids and CT measurement of liver volume were performed and then used to calculate amount of liver lipids. These data were compared with liver TG and Chol.

Results:

Percentage of liver water and liver density were persistent in two groups and were used to convert the percentage of liver lipids to liver water by 1H-MRS to the absolute amount of liver lipids per gram of liver or per milliliter of CT volume. Using 1H-MRS and biochemical assays, an increase of liver lipids was confirmed in mild steatosis mice compared to controls (P<0.01). The amounts of imaging detected liver lipids were strongly correlated to liver TG and Chol measured by biochemical assays in mild steatosis mice.

Conclusion:

1H MRS and CT liver imaging techniques are able to quantify absolute hepatic lipid levels utilizing relative persistent parameters percentage of liver water and liver density in a preclinical mild steatosis setting.

An Overview of the Current Management of Bilobar Colorectal Liver Metastases

Bilobar colorectal liver metastases (BCRLM) present a challenging scenario for liver surgeons globally. The following article aims to provide an overview of the different strategies which may be utilised in order to successfully manage advanced BCRLM.

Resection plane-dependent error in computed tomography volumetry of the right hepatic lobe in living liver donors

Background/Aims

Computed tomography (CT) hepatic volumetry is currently accepted as the most reliable method for preoperative estimation of graft weight in living donor liver transplantation (LDLT). However, several factors can cause inaccuracies in CT volumetry compared to real graft weight. The purpose of this study was to determine the frequency and degree of resection plane-dependent error in CT volumetry of the right hepatic lobe in LDLT.

Methods

Forty-six living liver donors underwent CT before donor surgery and on postoperative day 7. Prospective CT volumetry (V_P) was measured via the assumptive hepatectomy plane. Retrospective liver volume (V_R) was measured using the actual plane by comparing preoperative and postoperative CT. Compared with intraoperatively measured weight (W), errors in percentage (%) V_P and V_R were evaluated. Plane-dependent error in V_P was defined as the absolute difference between V_P and V_R. % plane-dependent error was defined as follows: |V_P–V_R|/W∙100.

Results

Mean V_P, V_R, and W were 761.9 mL, 755.0 mL, and 696.9 g. Mean and % errors in V_P were 73.3 mL and 10.7%. Mean error and % error in V_R were 64.4 mL and 9.3%. Mean plane-dependent error in V_P was 32.4 mL. Mean % plane-dependent error was 4.7%. Plane-dependent error in V_P exceeded 10% of W in approximately 10% of the subjects in our study.

Conclusions

There was approximately 5% plane-dependent error in liver V_P on CT volumetry. Plane-dependent error in V_P exceeded 10% of W in approximately 10% of LDLT donors in our study. This error should be considered, especially when CT volumetry is performed by a less experienced operator who is not well acquainted with the donor hepatectomy plane.

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%.

The error analysis of Lobular and segmental division of right liver by volume measurement

The aim of this study is to explore the inconsistencies between right liver volume as measured by imaging and the actual anatomical appearance of the right lobe. Five healthy donated livers were studied. The liver slices were obtained with hepatic segments multicolor-infused through the portal vein. In the slices, the lobes were divided by two methods: radiological landmarks and real anatomical boundaries. The areas of the right anterior lobe (RAL) and right posterior lobe (RPL) on each slice were measured using Photoshop CS5 and AutoCAD, and the volumes of the two lobes were calculated. There was no statistically significant difference between the volumes of the RAL or RPL as measured by the radiological landmarks (RL) and anatomical boundaries (AB) methods. However, the curves of the square error value of the RAL and RPL measured using CT showed that the three lowest points were at the cranial, intermediate, and caudal levels. The U- or V-shaped curves of the square error rate of the RAL and RPL revealed that the lowest value is at the intermediate level and the highest at the cranial and caudal levels. On CT images, less accurate landmarks were used to divide the RAL and RPL at the cranial and caudal layers. The measured volumes of hepatic segments VIII and VI would be less than their true values, and the measured volumes of hepatic segments VII and V would be greater than their true values, according to radiological landmarks. Clin. Anat. 30:585-590, 2017. © 2017 Wiley Periodicals, Inc.

Comparison of MRI- and CT-based semiautomated liver segmentation: a validation study

PURPOSE

To compare the repeatability, agreement, and efficiency of MRI- and CT-based semiautomated liver segmentation for the assessment of total and subsegmental liver volume.

METHODS

This retrospective study was conducted in 31 subjects who underwent contemporaneous liver MRI and CT. Total and subsegmental liver volumes were segmented from contrast-enhanced 3D gradient-recalled echo MRI sequences and CT images. Semiautomated segmentation was based on variational interpolation and Laplacian mesh optimization. All segmentations were repeated after 2 weeks. Manual segmentation of CT images using an active contour tool was used as the reference standard. Repeatability and agreement of the methods were evaluated with intra-class correlation coefficients (ICC) and Bland-Altman analysis. Total interaction time was recorded.

RESULTS

Intra-reader ICC were ≥0.987 for MRI and ≥0.995 for CT. Intra-reader repeatability was 30 ± 217 ml (bias ± 1.96 SD) (95% limits of agreement: -187 to 247 ml) for MRI and -10 ± 143 ml (-153 to 133 ml) for CT. Inter-method ICC between semiautomated and manual volumetry were ≥0.995 for MRI and ≥0.986 for CT. Inter-method segmental ICC varied between 0.584 and 0.865 for MRI and between 0.596 and 0.890 for CT. Inter-method agreement was -14 ± 136 ml (-150 to 122 ml) for MRI and 50 ± 226 ml (-176 to 276 ml) for CT. Inter-method segmental agreement ranged from 10 ± 47 ml (-37 to 57 ml) to 2 ± 214 ml (-212 to 216 ml) for MRI and 9 ± 45 ml (-36 to 54 ml) to -46 ± 183 ml (-229 to 137 ml) for CT. Interaction time (mean ± SD) was significantly shorter for MRI-based semiautomated segmentation (7.2 ± 0.1 min, p < 0.001) and for CT-based semiautomated segmentation (6.5 ± 0.2 min, p < 0.001) than for CT-based manual segmentation (14.5 ± 0.4 min).

CONCLUSION

MRI-based semiautomated segmentation provides similar repeatability and agreement to CT-based segmentation for total liver volume.

Assessment of Volumetric versus Manual Measurement in Disseminated Testicular Cancer; No Difference in Assessment between Non-Radiologists and Genitourinary Radiologist

BACKGROUND

The aim of this study was to assess the feasibility and reproducibility of semi-automatic volumetric measurement of retroperitoneal lymph node metastases in testicular cancer (TC) patients treated with chemotherapy versus the standardized manual measurements based on RECIST criteria.

METHODS

21 TC patients with retroperitoneal lymph node metastases of testicular cancer were studied with a CT scan of chest and abdomen before and after cisplatin based chemotherapy. Three readers, a surgical resident, a radiological technician and a radiologist, assessed tumor response independently using computerized volumetric analysis with Vitrea software® and manual measurement according to RECIST criteria (version 1.1). Intra- and inter-rater variability were evaluated with intra class correlations and Bland-Altman analysis.

RESULTS

Assessment of intra observer and inter observer variance proved non-significant in both measurement modalities. In particularly all intraclass correlation (ICC) values for the volumetric analysis were > .99 per observer and between observers. There was minimal bias in agreement for manual as well as volumetric analysis.

CONCLUSION

In this study volumetric measurement using Vitrea software® appears to be a reliable, reproducible method to measure initial tumor volume of retroperitoneal lymph node metastases of testicular cancer after chemotherapy. Both measurement methods can be performed by experienced non-radiologists as well.

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.

Liver graft hyperperfusion in the early postoperative period promotes hepatic regeneration 2 weeks after living donor liver transplantation: A prospective observational cohort study

Hepatic regeneration is essential to meet the metabolic demands of partial liver grafts following living donor liver transplantation (LDLT). Hepatic regeneration is promoted by portal hyperperfusion of partial grafts, which produces shear stress on the sinusoidal endothelium. Hepatic regeneration is difficult to assess within the first 2 weeks after LDLT as the size of liver graft could be overestimated in the presence of postsurgical graft edema. In this study, we evaluated the effects of graft hyperperfusion on the rate of hepatic regeneration 2 weeks after LDLT by measuring hepatic hemodynamic parameters. Thirty-six patients undergoing LDLT were enrolled in this study. Hepatic hemodynamic parameters including peak portal venous flow velocity (PVV) were measured using spectral Doppler ultrasonography on postoperative day 1. Subsequently, we calculated the ratio of each velocity to 100 g of the initial graft weight (GW) obtained immediately after graft retrieval on the day of LDLT. Ratios of GW to recipient weight (GRWR) and to standard liver volume (GW/SLV) were also obtained. The hepatic regeneration rate was defined as the ratio of the regenerated volume measured using computed tomographic volumetry at postoperative week 2 to the initial GW. Correlations of the hemodynamic parameters, GRWR, and GW/SLV with the hepatic regeneration rate were assessed using a linear regression analysis. The liver grafts regenerated to approximately 1.7 times their initial GW (1.7 ± 0.3 [mean ± standard deviation]). PVV/100 g of GW (r = 0.224, β1 [slope coefficient] = 2.105, P = 0.004) and velocities of the hepatic artery and vein per 100 g of GW positively correlated with the hepatic regeneration rate, whereas GRWR (r = 0.407, β1 = -81.149, P < 0.001) and GW/SLV (r = 0.541, β1 = -2.184, P < 0.001) negatively correlated with the hepatic regeneration rate. Graft hyperperfusion demonstrated by increased hepatic vascular velocities and a small-sized graft in the early postoperative period contributes to hepatic regeneration 2 weeks after LDLT.

Modified Hepatic Venous Plane: A Key Factor for Improving Preoperative MDCT Donor Volume Prediction in Living-Donor Liver Transplantation

OBJECTIVE

The aim of this work was to present our experience using a modified hepatic venous plane in multidetector computerized tomography (MDCT) for reducing the discrepancy between preoperative liver volume estimation and intraoperative weight (IOW) measurement in living-donor liver transplantation (LDLT).

METHODS

We retrospectively reviewed the medical records of 57 consecutive living donors with the use of MDCT as a modality for volumetric assessment for LDLT from May 2007 to January 2015. We divided living donors into 2 groups according to surgical methods: right hepatectomy (RH) and left hepatectomy (LH). Initial liver volumetric measurement (group I) was assessed. After discussions with radiologist, the transplantation surgeon used a modified hepatic venous plane for surgical significant middle hepatic venous variants (>5 mm) in 16 living donors and applied the initial surgical plane in the remaining for the modified donor liver volumetric measurement (group II). We then compared the correlations of these 2 groups with the use of IOW.

RESULTS

The overall correlation (r) between group I and IOW was 0.947. The correlations (r) between group I and IOW were 0.872 and 0.955 for RH and LH, respectively. Compared with group I, group II showed better correlation with IOW: r = 0.949 and 0.981 for RH and LH, respectively. The overall correlation (r) between group II and IOW was 0.980, and the error ratio was 5.95 ± 5.05%.

CONCLUSIONS

Our study showed that using a modified hepatic venous plane in preoperative MDCT, after good communication between transplant surgeon and radiologist, can provide more accurate liver volume estimation and achieve a better correlation with IOW in LDLT.

Computer-aided liver volumetry: performance of a fully-automated, prototype post-processing solution for whole-organ and lobar segmentation based on MDCT imaging

PURPOSE

To evaluate the performance of a prototype, fully-automated post-processing solution for whole-liver and lobar segmentation based on MDCT datasets.

MATERIALS AND METHODS

A polymer liver phantom was used to assess accuracy of post-processing applications comparing phantom volumes determined via Archimedes' principle with MDCT segmented datasets. For the IRB-approved, HIPAA-compliant study, 25 patients were enrolled. Volumetry performance compared the manual approach with the automated prototype, assessing intraobserver variability, and interclass correlation for whole-organ and lobar segmentation using ANOVA comparison. Fidelity of segmentation was evaluated qualitatively.

RESULTS

Phantom volume was 1581.0 ± 44.7 mL, manually segmented datasets estimated 1628.0 ± 47.8 mL, representing a mean overestimation of 3.0%, automatically segmented datasets estimated 1601.9 ± 0 mL, representing a mean overestimation of 1.3%. Whole-liver and segmental volumetry demonstrated no significant intraobserver variability for neither manual nor automated measurements. For whole-liver volumetry, automated measurement repetitions resulted in identical values; reproducible whole-organ volumetry was also achieved with manual segmentation, p(ANOVA) 0.98. For lobar volumetry, automated segmentation improved reproducibility over manual approach, without significant measurement differences for either methodology, p(ANOVA) 0.95-0.99. Whole-organ and lobar segmentation results from manual and automated segmentation showed no significant differences, p(ANOVA) 0.96-1.00. Assessment of segmentation fidelity found that segments I-IV/VI showed greater segmentation inaccuracies compared to the remaining right hepatic lobe segments.

CONCLUSION

Automated whole-liver segmentation showed non-inferiority of fully-automated whole-liver segmentation compared to manual approaches with improved reproducibility and post-processing duration; automated dual-seed lobar segmentation showed slight tendencies for underestimating the right hepatic lobe volume and greater variability in edge detection for the left hepatic lobe compared to manual segmentation.

Gd-EOB enhanced MRI T1-weighted 3D-GRE with and without elevated flip angle modulation for threshold-based liver volume segmentation

BACKGROUND

Despite novel software solutions, liver volume segmentation is still a time-consuming procedure and often requires further manual optimization. With the high signal intensity of the liver parenchyma in Gd-EOB enhanced magnetic resonance imaging (MRI), liver volume segmentation may be improved.

PURPOSE

To evaluate the practicability of threshold-based segmentation of the liver volume using Gd-EOB-enhanced MRI including a customized three-dimensional (3D) sequence.

MATERIAL AND METHODS

A total of 20 patients examined with Gd-EOB MRI (hepatobiliary phase T1-weighted (T1W) 3D sequence [VIBE]; flip angle [FA], 10° and 30°) were enrolled in this retrospective study. The datasets were independently processed by two blinded observers (O1 and O2) in two ways: manual (man) and threshold-based (thresh; study method) segmentation of the liver each followed by an optimization step (man+opt and thresh+opt; man+opt [FA10°] served as reference method). Resulting liver volumes and segmentation times were compared. A liver conversion factor was calculated in percent, describing the non-hepatocellular fraction of the total liver volume, i.e. bile ducts and vessels.

RESULTS

Thresh+opt (FA10°) was significantly faster compared to the reference method leading to a median volume overestimation of 4%/8% (P < 0.001). Using thresh+opt (FA30°), segmentation was even faster (P < 0.001) and even reduced median volume deviation of 0%/2% (O1/O2; both P > 0.2). The liver conversion factor was found to be 10%.

CONCLUSION

Threshold-based liver segmentation employing Gd-EOB-enhanced hepatobiliary phase standard T1W 3D sequence is accurate and time-saving. The performance of this approach can be further improved by increasing the FA.

Conditioning With Sevoflurane in Liver Transplantation: Results of a Multicenter Randomized Controlled Trial

BACKGROUND

During times of organ scarcity and extended use of liver grafts, protective strategies in transplantation are gaining importance. We demonstrated in the past that volatile anesthetics such as sevoflurane attenuate ischemia-reperfusion injury during liver resection. In this randomized study, we examined if volatile anesthetics have an effect on acute graft injury and clinical outcomes after liver transplantation.

METHODS

Cadaveric liver transplant recipients were enrolled from January 2009 to September 2012 at 3 University Centers (Zurich/Sao Paulo/Ghent). Recipients were randomly assigned to propofol (control group) or sevoflurane anesthesia. Postoperative peak of aspartate transaminase was defined as primary endpoint, secondary endpoints were early allograft dysfunction, in-hospital complications, intensive care unit, and hospital stay.

RESULTS

Ninety-eight recipients were randomized to propofol (n = 48) or sevoflurane (n = 50). Median peak aspartate transaminase after transplantation was 925 (interquartile range, 512-3274) in the propofol and 1097 (interquartile range, 540-2633) in the sevoflurane group. In the propofol arm, 11 patients (23%) experienced early allograft dysfunction, 7 (14%) in the sevoflurane one (odds ratio, 0.64 (0.20 to 2.02, P = 0.45). There were 4 mortalities (8.3%) in the propofol and 2 (4.0%) in the sevoflurane group. Overall and major complication rates were not different. An effect on clinical outcomes was observed favoring the sevoflurane group (less severe complications), but without significance.

CONCLUSIONS

This first multicenter trial comparing propofol with sevoflurane anesthesia in liver transplantation shows no difference in biochemical markers of acute organ injury and clinical outcomes between the 2 regimens. Sevoflurane has no significant added beneficial effect on ischemia-reperfusion injury compared to propofol.

Validation of a semiautomated liver segmentation method using CT for accurate volumetry

RATIONALE AND OBJECTIVES

To compare the repeatability and agreement of a semiautomated liver segmentation method with manual segmentation for assessment of total liver volume on CT (computed tomography).

MATERIALS AND METHODS

This retrospective, institutional review board-approved study was conducted in 41 subjects who underwent liver CT for preoperative planning. The major pathologies encountered were colorectal cancer metastases, benign liver lesions and hepatocellular carcinoma. This semiautomated segmentation method is based on variational interpolation and 3D minimal path-surface segmentation. Total and subsegmental liver volumes were segmented from contrast-enhanced CT images in venous phase. Two image analysts independently performed semiautomated segmentations and two other image analysts performed manual segmentations. Repeatability and agreement of both methods were evaluated with intraclass correlation coefficients (ICC) and Bland-Altman analysis. Interaction time was recorded for both methods.

RESULTS

Bland-Altman analysis revealed an intrareader agreement of -1 ± 27 mL (mean ± 1.96 standard deviation) with ICC of 0.999 (P < .001) for manual segmentation and 12 ± 97 mL with ICC of 0.991 (P < .001) for semiautomated segmentation. Bland-Altman analysis revealed an interreader agreement of -4 ± 22 mL with ICC of 0.999 (P < .001) for manual segmentation and 5 ± 98 mL with ICC of 0.991 (P < .001) for semiautomated segmentation. Intermethod agreement was found to be 3 ± 120 mL with ICC of 0.988 (P < .001). Mean interaction time was 34.3 ± 16.7 minutes for the manual method and 8.0 ± 1.2 minutes for the semiautomated method (P < .001).

CONCLUSIONS

A semiautomated segmentation method can substantially shorten interaction time while preserving a high repeatability and agreement with manual segmentation.

Computerized segmentation of liver in hepatic CT and MRI by means of level-set geodesic active contouring

Computerized liver volumetry has been studied, because the current "gold-standard" manual volumetry is subjective and very time-consuming. Liver volumetry is done in either CT or MRI. A number of researchers have developed computerized liver segmentation in CT, but there are fewer studies on ones for MRI. Our purpose in this study was to develop a general framework for liver segmentation in both CT and MRI. Our scheme consisted of 1) an anisotropic diffusion filter to reduce noise while preserving liver structures, 2) a scale-specific gradient magnitude filter to enhance liver boundaries, 3) a fast-marching algorithm to roughly determine liver boundaries, and 4) a geodesic-active-contour model coupled with a level-set algorithm to refine the initial boundaries. Our CT database contained hepatic CT scans of 18 liver donors obtained under a liver transplant protocol. Our MRI database contains 23 patients with 1.5T MRI scanners. To establish "gold-standard" liver volumes, radiologists manually traced the contour of the liver on each CT or MR slice. We compared our computer volumetry with "gold-standard" manual volumetry. Computer volumetry in CT and MRI reached excellent agreement with manual volumetry (intra-class correlation coefficient = 0.94 and 0.98, respectively). Average user time for computer volumetry in CT and MRI was 0.57 ± 0.06 and 1.0 ± 0.13 min. per case, respectively, whereas those for manual volumetry were 39.4 ± 5.5 and 24.0 ± 4.4 min. per case, respectively, with statistically significant difference (p < .05). Our computerized liver segmentation framework provides an efficient and accurate way of measuring liver volumes in both CT and MRI.

Safety and efficacy of splenic artery embolization for portal hyperperfusion in liver transplant recipients: a 5-year experience

Severe portal hyperperfusion (PHP) after liver transplantation has been shown to cause intrahepatic arterial vasoconstriction secondary to increased adenosine washout (hepatic artery buffer response). Clinically, posttransplant PHP can cause severe cases of refractory ascites and hydrothorax. In the past, we reported our preliminary experience with the use of splenic artery embolization (SAE) as a way to reduce PHP. Here we present our 5-year experience with SAE in orthotopic liver transplantation (OLT). Between January 2007 and December 2011, 681 patients underwent OLT at our institution, and 54 of these patients underwent SAE for increased hepatic arterial resistance and PHP (n=42) or refractory ascites/hepatic hydrothorax (n=12). Patients undergoing SAE were compared to a control group matched by year of embolization, calculated Model for End-Stage Liver Disease score, and liver weight. SAE resulted in improvements in hepatic artery resistive indices (0.92±0.14 and 0.76±0.10 before and after SAE, respectively; P<0.001) and improved hepatic arterial blood flow (HAF; 15.6±9.69 and 28.7±14.83, respectively; P<0.001). Calculated splenic volumes and spleen/liver volume ratios were correlated with patients requiring SAE versus matched controls (P=0.002 and P=0.001, respectively). Among the 54 patients undergoing SAE, there was 1 case of postsplenectomy syndrome. No abscesses, significant infections, or bleeding was noted. We thus conclude that SAE is a safe and effective technique able to improve HAF parameters in patients with elevated portal venous flow and its sequelae.

Validation of computed tomography for measuring lung weight

Background

Lung weight characterises severity of pulmonary oedema and predicts response to mechanical ventilation. The aim of this study was to evaluate the accuracy of quantitative analysis of thorax computed tomography (CT) for measuring lung weight in pigs with or without pulmonary oedema.

Methods

Thirty-six pigs were mechanically ventilated with different tidal volumes and positive end-expiratory pressures that did or did not induce pulmonary oedema. After 54 h, they underwent thorax CT (CT_{in vivo}) and were then sacrificed and exsanguinated. Fourteen pigs underwent a second thorax CT (CT_post-exsang.) after exsanguination. Lungs were excised and weighed with a balance (balance_post-exsang.). Agreement between lung weights measured with the balance (considered as reference) and those estimated by quantitative analysis of CT was assessed with Bland-Altman plots.

Results

One animal unexpectedly died before CT_{in vivo}. In 35 pigs, lung weight measured with balance_post-exsang. was 371 ± 184 g and that estimated with CT_{in vivo} was 481 ± 189 g (p < 0.001). Bias between methods was −111 g (−35%) and limits of agreement were −176 (−63%) and −46 g (−8%). Measurement error was similar in animals with (−112 ± 45 g; n = 11) or without (−110 ± 27 g; n = 24) pulmonary oedema (p = 0.88). In 14 pigs with thorax CT after exsanguination, lung weight measured with balance_post-exsang. was 342 ± 165 g and that estimated with CT_post-exsang. was 352 ± 160 g (p = 0.02). Bias between methods was −9 g (−4%) and limits of agreement were −36 (−11%) and 17 g (3%). Measurement errors were similar in pigs with (−1 ± 26 g; n = 11) or without (−12 ± 7 g; n = 3) pulmonary oedema (p = 0.12).

Conclusions

Compared to the balance, CT obtained in vivo constantly overestimated the lung weight, as it included pulmonary blood (whereas the balance did not). By contrast, CT obtained after exsanguination provided accurate and reproducible results.

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.

Manual contouring based volumetric evaluation for colorectal cancer with liver limited metastases: a comparison with RECIST

BACKGROUND

To compare response evaluation criteria in solid tumours (RECIST) and volumetric evaluation (VE) for colorectal cancer with liver-limited metastasis.

PATIENTS AND METHODS

VE of liver metastases was performed by manual contouring before and after chemotherapy on 45 pairs of computed tomography (CT) images in 36 patients who suffered from metastatic colorectal cancer (mCRC) with liver metastasis only. Cohen kappa was used to compare the agreement between VE and RECIST. Pearson correlation was performed for their comparison after cubic root transformation of the aggregate tumor volumes. Logistic regression was done to identify clinical and radiographic factors to account for the difference which may be predictive in overall response (OR).

RESULTS

There were 16 partial response (PR), 23 stable disease (SD) and 6 progressive disease (PD) cases with VE, and 14 PR, 23 SD and 8 PD with RECIST. VE demonstrated good agreement with RECIST (κ=0.779). Discordant objective responses were noted in 6 pairs of comparisons (13.3%). Pearson correlation also showed excellent correlation between VE and RECIST (r2=0.966, p<0.001). Subgroup analysis showed that VE was in slightly better agreement with RECIST for enlarging lesions than for shrinking lesions (r2=0.935 and r2=0.780 respectively). No factor was found predictive of the difference in OR between VE and RECIST.

CONCLUSIONS

VE exhibited good agreement with RECIST. It might be more useful than RECIST in evaluation shrinking lesions in cases of numerous and conglomerate liver metastases.

Hemodynamics of a hydrodynamic injection

The hemodynamics during a hydrodynamic injection were evaluated using cone beam computed tomography (CBCT) and fluoroscopic imaging. The impacts of hydrodynamic (5 seconds) and slow (60 seconds) injections into the tail veins of mice were compared using 9% body weight of a phase-contrast medium. Hydrodynamically injected solution traveled to the heart and drew back to the hepatic veins (HV), which led to liver expansion and a trace amount of spillover into the portal vein (PV). The liver volumes peaked at 165.6 ± 13.3% and 165.5 ± 11.9% of the original liver volumes in the hydrodynamic and slow injections, respectively. Judging by the intensity of the CBCT images at the PV, HV, right atrium, liver parenchyma (LP), and the inferior vena cava (IVC) distal to the HV conjunction, the slow injection resulted in the higher intensity at PV than at LP. In contrast, a significantly higher intensity was observed in LP after hydrodynamic injection in comparison with that of PV, suggesting that the liver took up the iodine from the blood flow. These results suggest that the enlargement speed of the liver, rather than the expanded volume, primarily determines the efficiency of hydrodynamic delivery to the liver.

Hemodynamics of a hydrodynamic injection

The hemodynamics during a hydrodynamic injection were evaluated using cone beam computed tomography (CBCT) and fluoroscopic imaging. The impacts of hydrodynamic (5 seconds) and slow (60 seconds) injections into the tail veins of mice were compared using 9% body weight of a phase-contrast medium. Hydrodynamically injected solution traveled to the heart and drew back to the hepatic veins (HV), which led to liver expansion and a trace amount of spillover into the portal vein (PV). The liver volumes peaked at 165.6 ± 13.3% and 165.5 ± 11.9% of the original liver volumes in the hydrodynamic and slow injections, respectively. Judging by the intensity of the CBCT images at the PV, HV, right atrium, liver parenchyma (LP), and the inferior vena cava (IVC) distal to the HV conjunction, the slow injection resulted in the higher intensity at PV than at LP. In contrast, a significantly higher intensity was observed in LP after hydrodynamic injection in comparison with that of PV, suggesting that the liver took up the iodine from the blood flow. These results suggest that the enlargement speed of the liver, rather than the expanded volume, primarily determines the efficiency of hydrodynamic delivery to the liver.