Reliability and accuracy of straightforward measurements for liver volume determination in ultrasound and computed tomography compared to real volumetry

Variability in Liver Size Measurements Using Different View Angles in Ultrasound Imaging

PURPOSE

The aim of this study was to compare liver size measurements in different conventional B-mode ultrasound image (US) field views using magnetic resonance imaging (MRI) measurement as a reference.

METHODS

After receiving Institutional Review Board approval and informed consent, three operators measured the largest sagittal and transverse dimensions of adult livers on three US image field views (90°, 120°, and 140°) with a single curvilinear transducer. We analyzed the differences in liver size across three image field views using one-way analysis of variance (ANOVA) and examined the correlations between MRI and ultrasound measurements using Spearman regression. We used 95% Bland-Altman limits of agreement (95% LOA) to analyze the confidence interval for liver size measurements between MRI and US. Intra-observer and inter-observer reliability in measuring liver size were assessed using intraclass correlation coefficient (ICC).

RESULTS

Based on sagittal liver length, 28 adult participants (7 men and 21 women, mean age 43 years) were divided into Group 1 (<17 cm, n = 10) or Group 2 (≥17 cm, n = 18). There was a significant difference in the liver size measurements across the three image field views (P < .001) in both groups. The highest correlation in liver size measurements between MRI and US was with ultra-wide-view (R2 = .87 in sagittal; R2 = .79 in transverse). Bland-Altman LOA also indicated good agreement between MRI and ultra-wide-view measurements. Intra-observer and inter-observer reliability in measuring liver size were good (ICC = 0.82-0.98).

CONCLUSION

The study suggests that ultrasound ultra-wide-view provides the most accurate liver size measurement and good intra- and inter-operator reliability.

Comparative evaluation of volumetry estimation from plain and contrast enhanced computed tomography liver images

OBJECTIVES

Surgery planning for liver tumour is carried out using contrast enhanced computed tomography (CECT) images to determine the optimal resection strategy and to assess the volume of liver and tumour. Current surgery planning tools interpret even the functioning liver cells present within the tumour boundary as tumour. Plain CT images provide inadequate information for treatment planning. This work attempts to address two shortcomings of existing surgery planning tools: (i) to delineate functioning liver cells from the non-functioning tumourous tissues within the tumour boundary and (ii) to provide 3D visualization and actual tumour volume from the plain CT images.

METHODS

All slices of plain CT images containing liver are enhanced by means of fuzzy histogram equalization in Non-Subsampled Contourlet Transform (NSCT) domain prior to 3D reconstruction to clearly delineate liver, non-functioning tumourous tissues and functioning liver cells within the tumour boundary. The 3D analysis from plain and CECT images was carried out on five types of liver lesions viz. HCC, metastasis, hemangioma, cyst, and abscess along with normal liver.

RESULTS

The study resulted in clear delineation of functional liver tissues from non-functioning tumourous tissues within the tumour boundary from CECT as well as plain CT images. The volume of liver calculated using the proposed approach is found comparable with that obtained using Myrian-XP, a currently followed surgery planning tool in clinical practice.

CONCLUSIONS

The obtained results from plain CT images will undoubtedly provide valuable diagnostic assistance and surgery planning even for the subset of patients for whom CECT acquisition is not advisable.

Evaluation of body mass index, ponderal index, visceral cross-sectional area, subcutaneous fat cross-sectional area, and liver volume as predictive factors for obesity-related comorbidities: a retrospective cohort study

BACKGROUND

The body mass index (BMI) is an imperfect clinical measure of obesity that should be used in conjunction with other valid measures of weight-related risk. We studied whether there is a superior measure of obesity-related comorbidities.

METHODS

Records of bariatric clinic patients who had an abdominal computed tomography (CT) within 1 year of visit were reviewed. The presence of obesity-related comorbidities was determined at the time of the scan. BMI and ponderal index (PI) were calculated, and CT scans were reviewed to determine the visceral cross-sectional area (VCSA), subcutaneous fat cross-sectional area (SFCSA), and liver volume (LV). Data were analyzed using the Kruskal-Wallis test and Mann-Whitney U test.

RESULTS

A higher number of comorbidities were found to be associated with a larger BMI (P = .011), VCSA (P = .014), SFCSA (P = .007), and LV (P = .014), but not a larger PI (P = .11). Of the 16 comorbidities assessed, VCSA and LV were associated with more than BMI and SFCSA. However, each measure could be associated with different comorbidities. A higher BMI was associated with increased insulin use (P = .034), hypertension (P = .007), and history of obstructive sleep apnea (P = .015), none of which were associated with PI. BMI and PI were the only measures associated with a history of deep vein thrombosis/pulmonary embolism (both P < .01). Only SFCSA was found to be associated with gastroesophageal reflux disease (P = .029). VCSA (P = .038) and LV (P = .001) were associated with nonalcoholic fatty liver disease.

CONCLUSION

No measure could account for all obesity-related comorbidities, implying the need for targeted measurements. However, PI was the least effective measure.

Evaluation of Various Methods of Liver Measurement in Comparison to Volumetric Segmentation Based on Computed Tomography

Background: A reliable assessment of liver volume, necessary before transplantation, remains a challenge. Our work aimed to assess the differences in the evaluation and measurements of the liver between independent observers and compare different formulas calculating its volume in relation to volumetric segmentation. Methods: Eight researchers measured standard liver dimensions based on 105 abdominal computed tomography (CT) scans. Based on the results obtained, the volume of the liver was calculated using twelve different methods. An independent observer performed a volumetric segmentation of the livers based on the same CT examinations. Results: Significant differences were found between the formulas and in relation to volumetric segmentation, with the closest results obtained for the Heinemann et al. method. The measurements of individual observers differed significantly from one another. The observers also rated different numbers of livers as enlarged. Conclusions: Due to significant differences, despite its time-consuming nature, the use of volumetric liver segmentation in the daily assessment of liver volume seems to be the most accurate method.

Liver volumetry and liver-regenerative interventions: history, rationale, and emerging tools

BACKGROUND

Postoperative hepatic insufficiency (PHI) is the most feared complication after hepatectomy. Volume of the future liver remnant (FLR) is one objectively measurable indicator to identify patients at risk of PHI. In this review, we summarized the development and rationale for the use of liver volumetry and liver-regenerative interventions and highlighted emerging tools that could yield new advancements in liver volumetry.

METHODS

A review of MEDLINE/PubMed, Embase, and Cochrane Library databases was conducted to identify literature related to liver volumetry. The references of relevant articles were reviewed to identify additional publications.

RESULTS

Liver volumetry based on radiologic imaging was developed in the 1980s to identify patients at risk of PHI and later used in the 1990s to evaluate grafts for living donor living transplantation. The field evolved in the 2000s by the introduction of standardized FLR based on the hepatic metabolic demands and in the 2010s by the introduction of the degree of hypertrophy and kinetic growth rate as measures of the FLR regenerative and functional capacity. Several liver-regenerative interventions, most notably portal vein embolization, are used to increase resectability and reduce the risk of PHI. In parallel with the increase in automation and machine assistance to physicians, many semi- and fully automated tools are being developed to facilitate liver volumetry.

CONCLUSION

Liver volumetry is the most reliable tool to detect patients at risk of PHI. Advances in imaging analysis technologies, newly developed functional measures, and liver-regenerative interventions have been improving our ability to perform safe hepatectomy.

Inter- and Intra-Rater Reliability of Ultrasound Measurements of Superficial and Deep Fasciae Thickness in Upper Limb

Ultrasound (US) imaging is increasingly the most used tool to measure the thickness of superficial and deep fasciae, but there are still some doubts about its reliability in this type of measurement. The current study sets out to assess the inter-rater and intra-rater reliability of US measurements of superficial and deep fasciae thicknesses in the arm and forearm. The study involved two raters: the first (R1) is an expert in skeletal–muscle US imaging and, in particular, the US assessment of fasciae; the second (R2) is a radiologist resident with 1 year’s experience in skeletal–muscle US imaging. R2, not having specific competence in the US imaging of fasciae, was trained by R1. R1 took US images following the protocol by Pirri et al. 2021, and the US-recorded images were analyzed separately by the two raters in different sessions. Each rater measured both types of fasciae at different regions and levels of the arm and forearm. Intra- and inter-rater reliability was excellent for the deep fascia and good and excellent for the superficial fascia according to the different regions/levels (for example for the anterior region of the arm: deep fascia: Ant 1: ICC_2,2 = 0.95; 95% CI = 0.81–0.98; superficial fascia: Ant 1: ICC_2,2 = 0.85, 95% CI = 0.79–0.88). These findings confirm that US imaging is a reliable and cost-effective tool for evaluating both fasciae, superficial and deep.