[Semi-automatic measurements of hepatic lobes. Application to study of liver volumes. Analysis of 50 computed tomography of normal liver]

Prediction of liver remnant regeneration after living donor liver transplantation using preoperative CT texture analysis

PURPOSE

To predict the rate of liver regeneration after living donor liver transplantation (LDLT) using pre-operative computed tomography (CT) texture analysis.

MATERIALS AND METHODS

112 living donors who performed right hepatectomy for LDLT were included retrospectively. We measured the volume of future remnant liver (FLR) on pre-operative CT and the volume of remnant liver (LR) on follow-up CT, taken at a median of 123 days after transplantation. The regeneration index (RI) was calculated using the following equation: [Formula: see text]. Computerized texture analysis of the semi-automatically segmented FLR was performed. We used a stepwise, multivariable linear regression to assess associations of clinical features and texture parameters in relation to RI and to make the best-fit predictive model.

RESULTS

The mean RI was 110.7 ± 37.8%, highly variable ranging from 22.4% to 247.0%. Among texture parameters, volume of FLR, standard deviation, variance, and gray level co-occurrence matrices (GLCM) contrast were found to have significant correlations between RI. In multivariable analysis, smaller volume of FLR (ß - 0.17, 95% CI - 0.22 to - 0.13) and lower GLCM contrast (ß - 1.87, 95% CI - 3.64 to - 0.10) were associated with higher RI. The regression equation predicting RI was following: RI = 203.82 + 10.42 × pre-operative serum total bilirubin (mg/dL) - 0.17 × V_FLR (cm³) - 1.87 × GLCM contrast (× 100).

CONCLUSION

Volume of FLR and GLCM contrast were independent predictors of RI, showing significant negative correlations. Pre-operative CT with texture analysis can be useful for predicting the rate of liver regeneration in living donor of liver transplantation.

Reference values of liver volume in Caucasian population and factors influencing liver size

PURPOSE

To investigate factors influencing liver size and to determine reference values of liver volume (LV) for healthy subjects.

METHODS

2773 volunteers underwent magnetic resonance imaging (MRI) of the liver in the setting of the population based Study of Health in Pomerania. Based on measurement of maximum diameters in three orientations, LVs were calculated and correlated with demographic factors such as age, gender, and body mass index. In addition, LVs of healthy volunteers and participants with parenchymal liver diseases such as fatty liver disease, iron overload, fibrosis/cirrhosis were compared. Adjusted reference values of liver volumes were defined for the group of healthy participants.

RESULTS

In general, mean LV (mean ± standard deviation) was 1505 ± 385 cm³. Age, gender and body mass index correlated significantly with the liver volume (p ≤ 0.001). Parenchymal liver diseases significantly influence LV (with: 1624 ± 420 cm³, n = 1525 and without parenchymal liver diseases: 1360 ± 273 cm³; n = 1.248, p ≤ 0.001). Compared to LV of participants without liver diseases, LV was increased in volunteers with hepatic steatosis (1717 ± 419 cm³; n = 1111), liver iron overload (1558 ± 367 cm³; n = 553; p ≤ 0.001) as well as in participants with fibrosis/cirrhosis (1494 ± 459 cm³; n = 383).

CONCLUSIONS

LV is influenced by age, body mass index and parenchymal liver diseases. Reference values were established to aid in the diagnosis of parenchymal liver diseases.

Automatic liver segmentation on Computed Tomography using random walkers for treatment planning

Segmentation of the liver from Computed Tomography (CT) volumes plays an important role during the choice of treatment strategies for liver diseases. Despite lots of attention, liver segmentation remains a challenging task due to the lack of visible edges on most boundaries of the liver coupled with high variability of both intensity patterns and anatomical appearances with all these difficulties becoming more prominent in pathological livers. To achieve a more accurate segmentation, a random walker based framework is proposed that can segment contrast-enhanced livers CT images with great accuracy and speed. Based on the location of the right lung lobe, the liver dome is automatically detected thus eliminating the need for manual initialization. The computational requirements are further minimized utilizing rib-caged area segmentation, the liver is then extracted by utilizing random walker method. The proposed method was able to achieve one of the highest accuracies reported in the literature against a mixed healthy and pathological liver dataset compared to other segmentation methods with an overlap error of 4.47 % and dice similarity coefficient of 0.94 while it showed exceptional accuracy on segmenting the pathological livers with an overlap error of 5.95 % and dice similarity coefficient of 0.91.

Assessment of liver volume variation to evaluate liver function

In order to assess the value of liver volumetry in cirrhosis and acute liver failure (ALF) patients, we explored the correlation between hepatic volume and severity of the hepatic diseases. The clinical data of 48 cirrhosis patients with 60 normal controls and 39 ALF patients were collected. Computed tomography-derived liver volume (CTLV) and body surface area (BSA) of normal controls were calculated to get a regression formula for standard liver volume (SLV) and BSA. Then CTLV and SLV of all patients were calculated and grouped by Child-Turcotte-Pugh classification for cirrhosis patients and assigned according to prognosis of ALF patients for further comparison. It turned out that the mean liver volume of the control group was 1,058 ± 337 cm(3). SLV was correlated with BSA according to the regression formula. The hepatic volume of cirrhosis patients in Child A, B level was not reduced, but in Child C level it was significantly reduced with the lowest liver volume index (CTLV/SLV). Likewise, in the death group of ALF patients, the volume index was significantly lower than that of the survival group. Based on volumetric study, we proposed an ROC (receiver operating characteristic) analysis to predict the prognosis of ALF patients that CTLV/SLV < 83.9% indicates a poor prognosis. In conclusion, the CTLV/SLV ratio, which reflects liver volume variations, correlates well with the liver function and progression of cirrhosis and ALF. It is also a very useful marker for predicting the prognosis of ALF.

Liver volume variations as a parameter to assess therapy response in advanced metastatic liver disease

BACKGROUND

The aim of this study was to evaluate liver volume variations (LVV) as a parameter to assess the therapy response in patients with advanced liver metastasis (aLM).

METHODS

Patients with colorectal cancer and consecutive computed tomography (CT) scans were divided into a group with aLM receiving palliative chemotherapy (n = 24) and a control group (n = 21) being followed after curative therapy. Liver volumetry was performed manually. The therapy response was assessed according to the response evaluation criteria in solid tumors (RECIST, n = 69). LVV were compared between groups and to variations in the sum-of-longest-diameter (SLDV). Using receiver operating characteristic (ROC) analysis, LVV were evaluated for distinguishing between progressive disease (PD) and stable disease (SD)/partial remission (PR).

RESULTS

Median LVV between patients with aLM (10.0%) and the control group (4.0%) differed significantly (p < 0.01). PD led to a larger median LVV (26.8%) than PR/SD (5.0%, p < 0.01). LVV in aLM patients correlated positively with SLDV (r = 0.71, p < 0.01). A cut-off value of 9.5% allowed distinguishing between PD and SD/PR (sensitivity: 86%, specificity: 88%, p < 0.01).

CONCLUSION

LVV are helpful to assess PD in patients with aLM.

Clinical application of measurement of liver volume by multi-slice spiral CT

The volume of the liver can not only directly reflect the size of the liver, liver capacity and the quantity of liver cells, but also, to a certain extent, indirectly reflect blood perfusion and metabolic capability of the liver. Therefore, liver volume is an important parameter to evaluate hepatic reserve function. The accurate measurement of liver volume has great significance for the formulation of treatment program, prevention of liver failure, and prediction of prognosis. This article is to review the clinical application of measurement of liver volume by multi-slice spiral CT.

Liver regeneration at day 7 after right hepatectomy: global and segmental volumetric analysis by using CT

PURPOSE

To evaluate total and segmental liver regeneration by comparing preoperative computed tomographic (CT) volumetry and CT volumetry on postoperative day 7 following right hepatectomy and to study liver regeneration estimated by using CT volumetry in patients with different surgical indications and in whom the middle hepatic vein (MHV) was harvested or not harvested.

MATERIALS AND METHODS

Local medical ethics committee and state medical board approval and informed consent were obtained. Twenty-seven patients who had undergone right hepatectomy were imaged with multidetector CT preoperatively and at day 7 postoperatively. Fourteen patients (group 1) were living liver donors, including eight in whom the MHV was harvested. Thirteen patients (group 2) underwent right hepatectomy for other indications. Volumetric measurements were performed semiautomatically. Total volumes and segmental volumes were measured for total liver, future liver remnant (FLR), and liver remnant. Total and segmental early regeneration index, defined as [(V(LR) - V(FLR))/V(FLR)] x 100, where V(LR) is volume of the liver remnant and V(FLR) is volume of the FLR, were calculated. Comparisons were performed by using the Mann-Whitney test, and a P value of less than .05 was considered significant.

RESULTS

The liver remnant at day 7 showed a 64% increase in volume from the FLR, without a significant difference between groups 1 and 2. In the group with harvesting of MHV, volume and segmental regeneration index were significantly lower than in other patients, for both the caudate lobe (32 and 48 mL, respectively; P = .049) and liver segment IV (Couinaud) (206 and 334 mL, respectively; P = .008).

CONCLUSION

Segmental regeneration of the liver following right hepatectomy varies, depending on whether the MHV was harvested, and seems to be related to hepatic outflow.

Liver volume variation in patients with virus-induced cirrhosis: findings on MDCT

OBJECTIVE

The objective of our study was to establish a standard liver volume formula and explore the correlation between hepatic lobe variations in patients with virus-induced cirrhosis and the severity of disease by measuring the volume of the whole liver, the left lateral segment, and the caudate lobe using 16-MDCT.

MATERIALS AND METHODS

The volume and per-body surface area (BSA) volume of the whole liver, the left lateral segment, and the caudate lobe were calculated in 113 patients with normal livers and 101 patients with virus-induced cirrhosis who underwent volume CT. The proportion of the left lateral segment volume and the proportion of the caudate lobe volume to the total liver volume, the volume index, and the volume change ratio were also calculated, and these data were grouped by Child-Pugh classification and compared. The standard liver volume formula was constructed from body weight and body height or from BSA.

RESULTS

There was a positive correlation between liver volume (LV) and body height, body weight (BW) [LV (cm3) = 12.90 x BW (kg) + 437.91], and BSA [LV (cm3) = 882.08 x BSA (m2) - 308.12]. The total mean +/- standard error (SE) liver volume of the control group was 1,222.76 +/- 216.96 cm3. The mean volumes of the whole liver and of the left lateral segment were 798.01 +/- 203.64 and 213.04 +/- 74.84 cm3, respectively, for Child-Pugh class C patients, which was significantly smaller than those values for Child-Pugh class A and B patients (p < 0.05). The mean volume of the caudate lobe was 36.83 +/- 22.11 cm3 for Child-Pugh class A patients, which is significantly larger than those values for Child-Pugh class B and C patients (p < 0.05).

CONCLUSION

CT-measured liver volume and standard liver volume formulas were helpful in evaluating liver volume variations. Enlargement of the left lateral segment was absolute in Child-Pugh class A and B patients, but was relative in Child-Pugh class C patients; enlargement of the caudate lobe was absolute in Child-Pugh class A patients, but was relative in Child-Pugh class B and C patients.