Accuracy and significance of pretransplant liver volume measured by magnetic resonance imaging

Utility of Longitudinal Measurement of the Liver With Ultrasound in Comparison to Computed Tomography Liver Volume in Assessing Hepatomegaly

ABSTRACT

The purpose of the study is to retrospectively compare the longitudinal measurement of the liver on ultrasound (US) with liver volume as measured on computed tomography (CT). This institutional review board-approved retrospective study with prospective image analysis included adult patients with US examinations of the liver and CT examinations of the abdomen performed within 2 weeks of each other from January 1, 2010, to April 30, 2016. We recorded the dome-to-tip longitudinal length measurement of the right lobe of the liver on the US study. The liver volume was calculated using manual 3-dimensional segmentation of the CT data set. Additional linear liver measurements and qualitative assessments were retrospectively made on the US and CT images. Hepatomegaly was defined as a liver volume 2000 mL or greater. The sample had 302 patients including 140 males and 162 females. Liver length measured on US had a moderate positive correlation with liver volume measured on CT, with a Pearson correlation coefficient of 0.7078. The optimum cutoff of liver length (US) was found to be 17 cm by Youden index, with a sensitivity of 76.0% and specificity of 73.4% for hepatomegaly. Additional linear measurements and qualitative assessments of the liver did not significantly improve the diagnosis of hepatomegaly. In conclusion, liver length measured with US has only a moderate correlation with liver volume. Commonly used US liver length maximum values of 16 to 18 cm produce a significant number of false-negatives and false-positives for the diagnosis of hepatomegaly.

Clinical and ultrasonographic investigations of 30 water buffaloes (Bubalus bubalis) with hepatomegaly

Background and Aim:

Knowledge of normal ultrasonographic dimensions of the liver and associated vascular structures is an important indicator for the diagnosis of hepatic diseases. Enlargement of the liver beyond its normal dimensions is the term of hepatomegaly and ultrasonography is the primary and the suitable diagnostic technique for this condition. Therefore, this study aimed to describe the clinical and ultrasonographic findings of liver diseases causing hepatomegaly in 30 buffaloes as well as to provide a range of liver dimensions and its blood vessel measurements in normal and diseased buffaloes.

Materials and Methods:

The study population included 30 buffaloes that were admitted to the clinic of the Faculty of Veterinary Medicine – Zagazig University for investigation of clinical signs associated with gastrointestinal diseases such as anorexia, chronic weight loss, and variable degrees of diarrhea or constipation. The animals were subjected to thorough clinical and ultrasonographic investigations. In addition, 10 healthy buffaloes were investigated ultrasonographically and post-slaughtering for comparison of liver dimensions and physical appearance.

Results:

Three conditions causing hepatomegaly were identified in this study as multiple focal hepatic lesions, diffuse fatty liver, and hepatic congestion. Clinically, it was difficult to differentiate between each condition while ultrasonography was the ideal tool for diagnosis after comparing with necropsy as a gold standard tool. Hepatomegaly was recorded in all affected animals with a significant decrease in the size of the portal vein (PV) and caudal vena cava (CVC) in animals affected with multiple focal hepatic lesions and fatty liver disease while the size of the PV and CVC was significantly increased in buffaloes with hepatic congestion.

Conclusion:

Ultrasonography can aid to accurately identify buffaloes with hepatomegaly and differentiate between different lesions involved.

Assessing the Non-tumorous Liver: Implications for Patient Management and Surgical Therapy

INTRODUCTION

Hepatic resection is performed for various benign and malignant liver tumors. Over the last several decades, there have been improvements in the surgical technique and postoperative care of patients undergoing liver surgery. Despite this, liver failure following an extended hepatic resection remains a critical potential postoperative complication. Patients with underlying parenchymal liver diseases are at particular risk of liver failure due to impaired liver regeneration with an associated mortality risk as high as 60 to 90%. In addition, live donor liver transplantation requires a thorough presurgical assessment of the donor liver to minimize the risk of postoperative complications.

RESULTS AND CONCLUSION

Recently, cross-sectional imaging assessment of diffuse liver diseases has gained momentum due to its ability to provide both anatomical and functional assessments of normal and abnormal tissues. Various imaging techniques are being employed to assess diffuse liver diseases including magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound (US). MRI has the ability to detect abnormal intracellular and molecular processes and tissue architecture. CT has a high spatial resolution, while US provides real-time imaging, is inexpensive, and readily available. We herein review current state-of-the-art techniques to assess the underlying non-tumorous liver. Specifically, we summarize current approaches to evaluating diffuse liver diseases including fatty liver alcoholic or non-alcoholic (NAFLD, AFLD), hepatic fibrosis (HF), and iron deposition (ID) with a focus on advanced imaging techniques for non-invasive assessment along with their implications for patient management. In addition, the role of and techniques to assess hepatic volume in hepatic surgery are discussed.

New formula for predicting standard liver volume in Chinese adults

AIM

To obtain a reference range of morphological indices and establish a formula to accurately predict standard liver volume (SLV) in Chinese adults.

METHODS

Computed tomography (CT)-estimated total liver volume (CTLV) was determined in 369 Chinese adults. Age, sex, body weight, body height, body mass index, and body surface area (BSA) were recorded using CT. Total splenic volume, portal venous diameter (PVD), splenic venous diameter (SVD), and portal venous cross-sectional area (PVCSA) were also measured by CT. Stepwise multiple linear regression analysis was performed to evaluate the impact of each parameter on CTLV and to develop a new SLV formula. The accuracy of the new formula was compared with the existing formulas in a validation group.

RESULTS

The average CTLV was 1205.41 ± 257.53 cm³ (range, 593.80-2250.10 cm³). The average of PVD, SVD and PVCSA was 9.34 ± 1.51 mm, 7.40 ± 1.31 mm and 173.22 ± 48.11 mm², respectively. The CT-estimated splenic volume of healthy adults varied markedly (range, 46.60-2892.30 cm³). Sex, age, body height, body weight, body mass index, and BSA were significantly correlated with CTLV. BSA showed the strongest correlation (r = 0.546, P < 0.001), and was used to establish a new model for calculating SLV: SLV (cm³) = 758.259 × BSA (m²)-124.272 (R² = 0.299, P < 0.001). This formula also predicted CTLV more accurately than the existing formulas, but overestimated CTLV in elderly subjects > 70 years of age, and underestimated liver volume when CTLV was > 1800 cm³.

CONCLUSION

Our new BSA-based formula is more accurate than other formulas in estimating SLV in Chinese adults.

Changes in Liver Volume in Patients with Chronic Hepatitis C Undergoing Antiviral Therapy

AIM

Liver volumetric analysis has not been used to detect hepatic remodelling during antiviral therapy before. We measured liver volume (LV) changes on volumetric magnetic resonance imaging during hepatitis C antiviral therapy.

METHODS

22 biopsy-staged patients (median [range] age 45(19-65) years; 9F, 13M) with chronic hepatitis C virus infection were studied. LV was measured at the beginning, end of treatment and 6 months post-treatment using 3D T1-weighted acquisition, normalised to patient weight. Liver outlines were drawn manually on 4 mm thick image slices and LV calculated. Inter-observer agreement was analysed. Patients were also assessed longitudinally using biochemical parameters and liver stiffness using Fibroscan™.

RESULTS

Sustained viral response (SVR) was achieved in 13 patients with a mean baseline LV/kg of 0.022 (SD 0.004) L/kg. At the end of treatment, the mean LV/kg was 0.025 (SD 0.004, P = 0.024 cf baseline LV/kg) and 0.026 (SD 0.004, P = 0.008 cf baseline LV/kg) 6 months post-treatment (P = 0.030 cf baseline, P = 0.004). Body weight-corrected end of treatment LV change was significantly higher in patients with SVR compared to patients not attaining SVR (P = 0.050). End of treatment LV change was correlated to initial ALT (R (2) = 0.479, P = 0.037), but not APRI, AST, viral load or liver stiffness measurements. There was a correlation of 0.89 between observers for measured slice thickness.

CONCLUSIONS

LV increased during anti-viral treatment, while the body weight-corrected LV increase persisted post-antiviral therapy and was larger in patients with SVR.

Liver volume in the cirrhotic patient: does size matter?

BACKGROUND

While it is established that cirrhosis results in a decrease in liver volume (LV), whether LV itself predicts patient survival is unknown. We hypothesize that estimated LV is an important prognostic indicator in patients with cirrhosis.

METHODS

Data was gathered retrospectively from consecutive patients evaluated for a liver transplant from January 2001 to June 2006. Of 500 patients identified, 323 patients met both inclusion and exclusion criteria. LV per ideal body weight (IBW) was used to correct for body size, and LV/IBW was stratified by median split for survival analyses. Patients were classified into one of three clinical groups: hepatocellular disease (n = 229), cholestatic disease (n = 56), and miscellaneous (n = 38). One of three possible clinical outcomes (survival, liver transplantation, or death) was recorded during the 5-year follow-up, the latter two grouped together as "transplant/death."

RESULTS

Transplant/death occurred in 283 (88 %) subjects. Overall, there was a significant increase in transplant/death in those with lower LV/IBW (χ(2) = 5.27, p = 0.022). When considering the subset with hepatocellular disease, lower LV/IBW was a robust predictor of transplant/death (χ(2) = 9.62, p = 0.002). In multivariate analyses, the LV/IBW trended toward predicting transplant/death (ExpB = 0.943, p = 0.053) independent of Model for End stage Liver Disease (MELD) (ExpB = 1.13, p = 0.001).

DISCUSSION

LV has important predictive value in patients with cirrhosis from hepatocellular disease. This observation appears to be independent of MELD, suggesting LV may impart important prognostic information that is not captured by the MELD score alone. Thus, LV may serve as an important adjunct to the MELD score in patients with hepatocellular disease.

Prospectively estimating the recoverability of renal function after relief of unilateral urinary obstruction by measurement of renal parenchymal volume

RATIONALE AND OBJECTIVES

Renal parenchymal volume (RPV) has been suggested as an indicator of the potential functional residual capacity for a given kidney. The goal of this study was to determine whether the recoverability of renal function could be predicted by RPV as estimated by computed tomography (CT) before an operation.

MATERIAL AND METHODS

Eighty-two adult patients diagnosed with long-term chronic unilateral ureteral obstruction and a normal contralateral kidney were recruited for evaluation. RPV was measured by nonenhanced CT. Glomerular filtration rate (GFR) was measured by radioisotope renal scan. Animal models were used to validate use of the CT method to measure RPV. RPV and GFR values for all patients were obtained before surgical relief of the urinary obstruction and compared with those values obtained at 12 months postsurgery.

RESULTS

There was no statistically significant difference found between RPV measured by CT or by the water displacement method. Among patient age, sex, and pre-RPV and pre-GFR of obstructed and contralateral kidney, pre-RPV and pre-GFR of obstructed kidney were the independent factors that best indicated recoverability of renal function. Pre-RPV correlated well with post-GFR (r = 0.68, P < .01). The cut-off point of pre-RPV to predict recoverability of renal function after the relief operation was 58.2 mL, as determined by receiver operating characteristic curve analysis.

CONCLUSION

Pre-RPV was the independent factor that determines recoverability of renal function. Renal function may stabilize or improve after relief of urinary obstruction when the pre-RPV value is ≥58.2 mL.

A simple method for accurate liver volume estimation by use of curve-fitting: a pilot study

In this paper, we describe the effectiveness of our curve-fitting method by comparing liver volumes estimated by our new technique to volumes obtained with the standard manual contour-tracing method. Hepatic parenchymal-phase images of 13 patients were obtained with multi-detector CT scanners after intravenous bolus administration of 120-150 mL of contrast material (300 mgI/mL). The liver contours of all sections were traced manually by an abdominal radiologist, and the liver volume was computed by summing of the volumes inside the contours. The section number between the first and last slice was then divided into 100 equal parts, and each volume was re-sampled by use of linear interpolation. We generated 13 model profile curves by averaging 12 cases, leaving out one case, and we estimated the profile curve for each patient by fitting the volume values at 4 points using a scale and translation transform. Finally, we determined the liver volume by integrating the sampling points of the profile curve. We used Bland-Altman analysis to evaluate the agreement between the volumes estimated with our curve-fitting method and the volumes measured by the manual contour-tracing method. The correlation between the volume measured by manual tracing and that estimated with our curve-fitting method was relatively high (r = 0.98; slope 0.97; p < 0.001). The mean difference between the manual tracing and our method was -22.9 cm(3) (SD of the difference, 46.2 cm(3)). Our volume-estimating technique that requires the tracing of only 4 images exhibited a relatively high linear correlation with the manual tracing technique.

Variation in hepatic segmental volume distribution according to different causes of liver cirrhosis: CT volumetric evaluation

OBJECTIVE

To investigate if there is difference in hepatic segmental volume distribution according to causes of liver cirrhosis (LC) using computed tomography volumetric analysis.

METHODS

On computed tomographic scans, hepatic segmental volumes were measured in 90 patients with LC of 4 different causes (alcohol, hepatitis B virus (HBV), hepatitis C virus (HCV), and cryptogenic cirrhosis). The volumetric indices were compared.

RESULTS

The volume proportion of the lateral segment in the liver in patients with HBV was significantly higher than in the patients with HCV (P = 0.038). Hepatic volume distribution in alcoholic LC showed differences: larger caudate lobe volume than HBV- and HCV-induced LC (P = 0.029 and P = 0.031), larger right lobe volume (P = 0.043) and smaller proportion of the lateral segment in the liver (P = 0.003) than in HBV-induced LC.

CONCLUSIONS

Computed tomography volumetric analysis showed differences in hepatic segmental volume distribution in cirrhotic patients according to causes of LC.

Freehand liver volumetry by using an electromagnetic pen tablet: accuracy, precision, and rapidity

The purpose of this study is to assess the accuracy, precision, and rapidity of liver volumes calculated by using a freehand electromagnetic pen tablet contourtracing method as compared with the volumes calculated by using the standard optical mouse contourtracing method. The imaging data used as input for accuracy and precision testing were computed by software developed in our institution. This computer software can generate models of solid organs and allows both standard mouse-based and electromagnetic pen-driven segmentation (number of data sets, n = 70). The images used as input for rapidity testing was partly computed by modeling software (n = 70) and partly selected from contrast-enhanced computed tomography (CT) examinations (n = 12). Mean volumes and time required to perform the segmentation, along with standard deviation and range values with both techniques, were calculated. Student's t test was used to assess significance regarding mean volumes and time calculated by using both segmentation techniques on phantom and CT data sets. P value was also calculated. The mean volume difference was significantly lower with the use of the freehand electromagnetic pen as compared with the optical mouse (0.2% vs. 1.8%; P < .001). The mean segmentation time per patient was significantly shorter with the use of the freehand electromagnetic pen contourtracing method (354.5 vs. 499.1 s on phantoms; 457.4 vs. 610.0 s on CT images; P < .001). Freehand electromagnetic pen-based volumetric technique represents a technologic advancement over manual mouse-based contourtracing because of the superior statistical accuracy and sensibly shorter time required. Further studies focused on intra- and interobserver variability of the technique need to be performed before its introduction in clinical application.

Hepatic volume measurements in dogs with extrahepatic congenital portosystemic shunts before and after surgical attenuation

BACKGROUND

In dogs with congenital portosystemic shunts (CPSS), the ability of the hypoplastic liver to grow is considered important for recovery after surgical shunt attenuation.

OBJECTIVES

This study investigated hepatic growth after extrahepatic shunt attenuation in dogs using magnetic resonance imaging (MRI) and computed tomography (CT).

ANIMALS

Ten client-owned dogs with single extrahepatic CPSS.

METHODS

Abdominal MRI, CT, or both were performed before and 8 days, 1, and 2 months after shunt attenuation. Liver volumes were calculated from the areas of the MRI or CT images.

RESULTS

Before surgery, median liver volume was 18.2cm3/kg body weight. Liver volume increased significantly after surgery. Growth was highest between days 0 and 8 and decreased afterward. Median liver volume was 28.8 cm3/kg at 2 months after attenuation. No significant differences in growth were found between dogs with complete or partial shunt closure or between dogs with complete or incomplete metabolic recovery. Volumes measured from consecutively performed MRI and CT images correlated well (r = 0.980), but volumes from MRI images were significantly larger than volumes from CT images (6.8%; P = .008).

CONCLUSION AND CLINICAL IMPORTANCE

After shunt attenuation, rapid normalization of liver size was observed. Hepatic growth was not decreased in dogs after partial closure of CPSS or in dogs with subclinical, persistent shunting 2 months after surgery. CT is the preferred imaging method for volumetric estimation because of speed.

An assessment of the accuracy of hepatic and splenic size based upon a clinician's physical examination, a radiologist's impression and the actual liver and spleen volumes calculated by CT scanning

OBJECTIVES

In this study, a radiologist's impression of liver and spleen size based on computed tomography (CT) images, calculated liver and spleen volumes as determined radiologically, and findings of a hepatologist were compared.

METHODS

One hundred and ninety-four consecutive subjects seen by a hepatologist were evaluated clinically and radiologically. Liver and spleen volumes were calculated based on CT images and compared to radiologist's impression and to expected liver volume based on body weight. Covariate analysis was used to determine the relationships between different variables, and a value of P < 0.05 was considered to be significant.

RESULTS

Liver volume calculated on the basis of CT scans correlated to liver size based on the hepatologist's clinical exam but not to the radiologist's impression of liver size. In contrast, spleen volume based on CT scans, splenic size based upon radiologist's impression, and clinician's assessment all correlated well.

CONCLUSIONS

A variety of biases determine and/or affect the radiologist's assessment of liver size but not of splenic size.

Preoperative weight loss with a very-low-energy diet: quantitation of changes in liver and abdominal fat by serial imaging

BACKGROUND

A very-low-energy diet (VLED) can result in substantial, rapid weight loss and is increasingly prescribed before obesity surgery to minimize risk and difficulty by reducing liver size and abdominal adiposity. Despite its growing popularity, a VLED in this setting has received little attention.

OBJECTIVE

The aim of this study was to investigate the efficacy and acceptability of a preoperative VLED.

DESIGN

In a prospective observational study, 32 subjects (n = 19 men and 13 women) with a mean (+/-SD) age of 47.5 +/- 8.3 y and a body mass index (in kg/m(2)) of 47.3 +/- 5.3 consumed a VLED for 12 wk. Primary outcomes included changes in liver volume (LV) and in visceral and subcutaneous adipose tissue (VAT/SAT). Changes in body weight, anthropometric measures, and biochemical variables were also recorded, and compliance with, acceptability of, and side effects of treatment were assessed. Changes in LV and VAT/SAT area were measured by computed tomography and magnetic resonance imaging at baseline and weeks 2, 4, 8, and 12.

RESULTS

Mean (+/-SD) LV, VAT/SAT, and body weight decreased significantly (P < 0.001 for all). The degree of LV reduction was directly related to the reduction in relative body weight (r = 0.54, P = 0.001) and initial LV (r = 0.43, P = 0.015). Eighty percent of the reduction in LV occurred between weeks 0 and 2 (P < 0.001). Reductions in body weight and VAT were uniform over the 12-wk period. Attrition was 14%. Acceptability was adequate but waned over time, and mild transitory side effects occurred.

CONCLUSIONS

Given the observed early reduction in LV and the progressive reduction in VAT, we suggest that the minimum duration for a preoperative VLED be 2 wk. Ideally, the duration should be 6 wk to achieve maximal LV reduction and significant reductions in VAT and body weight without compromising compliance and acceptability.

Portal vein embolisation prior to hepatic resection for colorectal liver metastases and the effects of periprocedure chemotherapy

Portal vein embolisation (PVE) is an effective method of increasing future liver remnant (FLR) but may stimulate tumour growth. The effect of periprocedure chemotherapy has not been established. 15 consecutive patients underwent PVE prior to hepatic resection for colorectal liver metastases with a FLR <30% of tumour-free liver (TFL). Liver and tumour volumes pre-PVE and 6 weeks post-PVE were calculated by CT or MRI volumetry and correlated with the periprocedure chemotherapy regimen. PVE increased the FLR from 18+/-5% of TFL to 27+/-8% post-PVE (p<0.01). Post-PVE chemotherapy did not prevent hypertrophy of the FLR but the volume increase with chemotherapy (median 89 ml, range 7-149 ml) was significantly reduced (median 135 ml, range 110-254 ml without chemotherapy) (p = 0.016). Tumour volume (TV) decreased in those receiving post-PVE chemotherapy (median TV decrease 8 ml, range -77 ml to +450 ml) and increased without chemotherapy (median TV increase 39 ml, range -58 ml to +239 ml). Of the 15 patients, eight underwent resection; four were not resected due to disease progression and three due to insufficient hypertrophy of the FLR. PVE increased the FLR by an average of 9% allowing resection in 50% of patients. Periprocedure chemotherapy did not prevent but did reduce hypertrophy. A trend towards tumour regression was observed.

Accuracy of sonographic volume measurements of kidney transplant

PURPOSE

Sonographic measurement of renal volume is one of the parameters used in the diagnosis of renal transplant dysfunction and in follow-up of patients with renal transplant. The aim of this study was to compare the prolate ellipsoid formula with a new formula in calculating the volume of a transplanted kidney.

METHODS

The renal volumes in 24 patients with a stable renal transplant were determined sonographically with the ellipsoid formula and via helical CT with the voxel-count method, which is the gold standard. A new formula that uses renal length and the cross-sectional area at the maximum transverse section has been evaluated in a small series of transplanted kidneys.

RESULTS

Renal volume was underestimated with the sonographic ellipsoid formula and the new formula. The new formula yielded the lowest underestimation of the mean renal volume, and the measurements obtained with it were not significantly different from those obtained with CT.

CONCLUSIONS

The use of sonography is appropriate for accurate calculation of renal volume, and the new formula that uses only 2 ultrasound parameters best represents the volume of a renal transplant.

Liver and Spleen Volumetry with Quantitative MR Imaging and Dual-Space Clustering Segmentation

The purpose of this HIPAA-compliant, institutional review board-approved study was to assess the liver and spleen volumes calculated by using a semiautomated dual-space clustering segmentation technique, as compared with the volumes calculated by using the manual contour-tracing method. The quantitative magnetic resonance (MR) imaging data used as input were computed from images acquired by using a mixed fast spin-echo pulse sequence that was implemented with respiratory triggering. Linear regression analysis was used to assess agreement regarding the volumes calculated by using both segmentation techniques. There was strong agreement regarding the regression parameters for the liver (r = 0.98, P < .001) and the spleen (r = 0.99, P < .001) and the mean percentage volume differences for the liver (1.2%) and the spleen (0.9%). The mean segmentation time per patient was significantly shorter with use of the dual-space clustering method (P < .001).

Assessment of the optimum section thickness for the estimation of liver volume using magnetic resonance images: a stereological gold standard study

Estimation of liver volume using magnetic resonance (MR) images has been described previously. We have, however, not found a gold standard study, which analyzes the effect of section thickness on the estimation of liver volume. In the present study, five normal cadaveric livers were scanned in the horizontal plane using a 1.5 T MR machine (Signa 1.5T SYS#GEMSOW General Electronic, Wisconsin, USA). Consecutive sections at a thickness of 10, 7.5, 5 and 2.5 mm were used to estimate the total volume of the livers by means of the Cavalieri principle. The point counting and planimetry were used for the volume estimates. With a view to evaluating the accuracy of two techniques, all the estimations were done by the same observer. The estimated volumes concur with the actual volume of the livers obtained by the fluid displacement technique (p > 0.05). However, the section thickness has an over- or under-projection effect on the estimated volume. The obtained volume estimation results were analyzed to reveal the deviation principles of the estimates based on the section thickness. The most suitable section thickness for the liver volume estimation was assessed to be 4-5 mm. There were no significant differences between the estimation results of two methods (p > 0.05). The point-counting technique did, however, take less time than planimetry for estimating liver volume from MR images. Results also showed that the effect of section thickness on volume estimates using the two approaches could not be omitted and the values obtained could be calibrated using the proposed regression formula presented in this study.

Liver volume in thalassaemia major: relationship with body weight, serum ferritin, and liver function

BACKGROUND

It is not known whether body weight alone can adjust for the volume of liver in the calculation of the chelating dose in beta-thalassaemia major patients, who frequently have iron overload and hepatitis.

OBJECTIVE

The hypothesis is that liver volume in children and adolescents suffering from beta-thalassaemia major is affected by ferritin level and liver function.

MATERIALS AND METHODS

Thirty-five beta-thalassaemia major patients aged 7-18 years and 35 age- and sex-matched controls had liver volume measured by MRI. Serum alanine aminotransferase (ALT) and ferritin levels were obtained in the thalassaemia major patients.

RESULTS

Body weight explained 65 and 86% of the change in liver volume in beta-thalassaemia major patients and age-matched control subjects, respectively. Liver volume/kilogram body weight was significantly higher (P < 0.001) in thalassaemia major patients than in control subjects. There was a significant correlation between ALT level and liver volume/kilogram body weight (r = 0.55, P = 0.001). Patients with elevated ALT had significantly higher liver volume/kilogram body weight (mean 42.9 +/- 12 cm3/kg) than control subjects (mean 23.4 +/- 3.6 cm3/kg) and patients with normal ALT levels (mean 27.4 +/- 3.6 cm3/kg).

CONCLUSIONS

Body weight is the most important single factor for liver-volume changes in thalassaemia major patients, but elevated ALT also has a significant role. Direct liver volume measurement for chelation dose adjustment may be advantageous in patients with elevated ALT.

Evaluation of Living Liver Transplant Donors: Method for Precise Anatomic Definition by Using a Dedicated Contrast-enhanced MR Imaging Protocol

Liver transplantation from a living donor involves removal of part of the donor liver in a fashion that does not endanger its vascular supply or metabolic function. The radiologist plays an important role in evaluation of the living donor to define the conditions under which graft donation is contraindicated and to identify anatomic variations that may alter the surgical approach. In the past, diagnostic work-up of the donor involved costly and invasive tests. Currently, dynamic contrast material-enhanced computed tomography and magnetic resonance (MR) imaging are the imaging tests performed, each of which has advantages and limitations. MR imaging performed with liver-specific and extravascular contrast agents may be used as a single imaging test for comprehensive noninvasive evaluation of living liver transplant donors. MR imaging provides valuable information about variations in the vascular and biliary anatomy and allows evaluation of the hepatic parenchyma for diffuse or focal abnormalities.

Comparison of two volumetric techniques for estimating liver volume using magnetic resonance imaging

PURPOSE

To compare the conventional technique of manual planimetry with the point counting technique for estimating liver volume from magnetic resonance imaging (MRI) data.

MATERIALS AND METHODS

This study comprised abdominal MR examinations of 38 consecutive patients. Evaluation of the images showed that liver size appeared normal in 27 patients and increased in 11. Liver volume was estimated using the techniques of planimetry and point counting. Both techniques were used in combination with the Cavalieri method of modern design stereology. A systematic slice sampling procedure was performed to estimate liver volumes using both volumetric techniques. The point counting technique was optimized by altering the point spacing of the grid. The agreement between the two techniques was found. Measurement repeatability of both volumetric techniques was also evaluated.

RESULTS

Both techniques allowed the same degree of optimization through the procedure of systematic section sampling. The application of a point spacing of 2.5 cm reduced the time measurement by a factor of 3.5 in relation with the time needed with planimetry. An excellent agreement was observed between the two volumetric techniques with mean differences (+/-SD) of 2.4 +/- 41.6 cm(3) and 8.5 +/- 49.8 cm(3) for the patients presenting normal and increased liver sizes, respectively. Both techniques were highly reproducible.

CONCLUSION

The point counting technique could be considered a more efficient approach than planimetry for estimating liver volume from MRI, due to its speed and simplicity.

Imaging of hepatic transplantation

Hepatic transplantation has become the treatment of choice for advanced irreversible liver disease. More than 4,000 hepatic transplantations were performed in the United States in 1997 and more than 11,000 are awaiting transplantation. Graft endurance and overall patient survival has been steadily improving, and between 1992 and 1994, 82% of the patients who received a liver transplant survived for at least a year. Today, liver transplant patients have a five-year survival rate of approximately 75%. The improvement in survival can be attributed to better patient selection and preparation, advances in organ preservation, improved immunosuppressive therapy agents and refinement of surgical techniques. In this article, we will address the hepatic parenchyma and vascular structures that should be evaluated prior to and following liver transplantation, the range of expected anomalies and abnormalities, and the utility of each of the three main imaging modalities, namely ultrasonography, computed tomography and magnetic resonance imaging in this assessment.

Preoperative portal vein embolisation for primary and metastatic liver tumours: volume effects, efficacy, complications and short-term outcome

BACKGROUND

The aim of portal vein embolisation is to induce hyperplasia of normal tissue when resection of a cancerous portion of the liver is contraindicated only by the volume of liver that would remain following operation.

METHODS

Eight patients with inoperable liver tumours (3 women and 5 men, median age 69.5 years, 3 colorectal hepatic metastasts, 2 choloangiocarcinomas and 3 hepatocellular cancers) were selected for portal vein embolisation. Selected portal branches were occluded with microparticles and coils. Liver volumes were determined by magnetic resonance imaging (MRI) before embolisation and again before operation.

RESULTS

Embolisation was successfully performed in all 8 patients, 7 by the percutaneous-transhepatic route, while one patient required open cannulation of a mesenteric vein. Management was altered in 6 patients who proceded to 'curative' resection; projected remaining liver volumes increased (Wilcoxon's matched pairs test p=0.02) from a median of 361 cc to a median of 550 cc; two patients had disease progression such that operation was no longer indicated. In one patient a misplaced coil unintentionally occluded a portal branch to normal liver.

CONCLUSIONS

Portal vein embolisation produced appreciable hyperplasia of the normal liver and extended the option of 'curative' operation to 6 out of the 8 cases attempted. Complications can occur. The long-term results following operation are unknown.

Accuracy and significance of computed tomographic scan assessment of hepatic volume in patients undergoing liver transplantation

BACKGROUND

A small liver volume is considered to be a poor prognostic factor in cirrhosis, often indicative of advanced liver disease. Radiologic assessment of liver volume before liver transplant is routinely performed in many transplant centers. We sought to assess the accuracy and significance of computed tomographic (CT) scanning in hepatic volumetric analysis by correlating CT-derived estimation of liver volume with that of corresponding liver explants.

METHODS

A chart review of all patients aged 17 years or older undergoing liver transplant at Mount Sinai Medical Center between 1989 and 1995 was performed. Each patient underwent conventional CT scanning with measurement of liver volume (CTLV). Recipient liver volume (RLV) was defined as weight of liver explant after all attached ligaments, portal structures, and gallbladder were dissected free. Expected liver volume was calculated pretransplant based on age, gender, height, and weight. Patients were categorized into three groups based on etiology of liver disease: (1) hepatocellular (e.g., viral hepatitis, alcohol-related), (2) cholestatic (e.g., primary biliary cirrhosis), and (3) cryptogenic. The ratio of CTLV to RLV was used as a measure of the accuracy of CT volumetric analysis.

RESULTS

A total of 579 patients was studied (group 1=376, group 2=139, group 3=64). All three groups were statistically similar with regard to age, prothrombin time and total bilirubin. Median CT liver volume was 1308 ml (range: 338-3847), 1651 ml (range: 641-3861), and 1210 ml (range: 348-2575) in groups 1-3, respectively; median ratio of CTLV to RLV was 1.02 (range: 0.50-2.31), 1.05 (range: 0.52-2.22), and 1.05 (range: 0.50-1.56) for groups 1-3, respectively. When RLV was small, it tended to be overestimated by CTLV. In contrast, when RLV was large, it was often underestimated. Clinical features such as history of esophageal variceal bleed, encephalopathy or ascites, and laboratory data did not influence accuracy of CT volumetric analysis.

CONCLUSIONS

CT-derived estimation of liver volume appears to correlate closely with actual weight of liver explant regardless of the etiology of chronic liver disease. With extremes in CT volumetric analysis, actual liver volume tends to be under- or overestimated. For patients with end-stage liver disease, both CT-derived and actual liver volume are greater in cholestatic than in hepatocellular disorders.

Renal volume measurements: accuracy and repeatability of US compared with that of MR imaging

PURPOSE

To determine the accuracy and repeatability of ultrasonography (US) with the ellipsoid formula in calculating the renal volume.

MATERIALS AND METHODS

The renal volumes in 20 volunteers aged 19-51 years were determined by using US with the ellipsoid formula and magnetic resonance (MR) imaging with the voxel-count method by two independent observers for each modality. The observers performed all measurements twice, with an interval between the first and second examinations. The voxel-count method was the reference standard. Repeatability was evaluated by calculating the SD of the difference (method of Bland and Altman).

RESULTS

Renal volume was underestimated with US by 45 mL (25%) on average. A comparable underestimation was found when the ellipsoid formula was applied to MR images. This indicates that the inaccuracy of US renal volume measurements (a) occurred because the kidney does not resemble an ellipsoid and (b) was not primarily related to the imaging modality. Intra- and interobserver variations in US volume measurements were poor; the SD of the difference was 21-32 mL. For comparison, the SD of the difference in reference-standard measurements was 5-10 mL.

CONCLUSION

Use of US with the ellipsoid formula is not appropriate for accurate and reproducible calculation of renal volume.