The Correlation between the CT Liver Volume and the Actual Weight of the Resected Cirrhotic Liver in Transplantation Patients

Objective: Volumetric assessment with computed tomography (CT), known as CT volumetry, is the preferred method for estimating future liver remnant. However, the data regarding the usage of CT volumetry to estimate future liver remnant of the diseased liver is still lacking. This study was designed to evaluate the correlation between the liver volume, calculated by CT, and the actual weight of the resected liver in patients who underwent orthotopic liver transplantation.Material and Methods: A total of 32 patients having underwent liver transplantation; from March 2009 to June 2015, were included. A radiologist retrospectively reviewed the pre-operative CT and performed the volume measurement. Statistical analysis was performed to determine the relationship between the estimated liver volume and the actual liver weight.Results: The estimated liver volume was significantly different among the cirrhosis of different etiology (p-value=0.001 for the total liver volume and p-value=0.003 for the functional liver volume). Compared with the total liver volume, the functional liver volume had a stronger correlation with the actual weight of the resected liver (r=0.955 vs. r=0.786). The following formula can be used to accurately estimate the expected weight of the resected liver (expected liver weight: ELW), based on the estimated functional liver volume (FLV) derived by CT volumetry: ELW=489.531+(0.618*FLV). The R-squared for this regression model was 0.914.Conclusion: CT volumetry is reliable and accurate in predicting the actual amount of the resected liver parenchyma in cirrhotic patients.

Comparison of CT Volumetry versus Nuclear Renography for Predicting Remaining Kidney Function After Uninephrectomy in Living Kidney Donors

Computed tomography (CT) and nuclear renography are used to determine kidney procurement in living kidney donors (LKDs). The present study investigated which modality better predicts kidney function after donation. This study included 835 LKDs and they were divided into two subgroups based on whether the left-right dominance of kidney volume was concordant with kidney function (concordant group) or not (discordant group). The predictive value for post-donation kidney function between the two imaging modalities was compared at 1 month, 6 months, and > 1 year in total cohort, concordant, and discordant groups. Split kidney function (SKF) measured by both modalities showed significant correlation with each other at baseline. SKFs of remaining kidney measured using both modalities before donation showed significant correlation with eGFR (estimated glomerular filtration rate) after donation in the total cohort group and two subgroups, respectively. CT volumetry was superior to nuclear renography for predicting post-donation kidney function in the total cohort group and both subgroups. In the discordant subgroup, a higher tendency of kidney function recovery was observed when kidney procurement was determined based on CT volumetry. In conclusion, CT volumetry is preferred when determining procurement strategy especially when discordance is found between the two imaging modalities.

Assessing the role of the pelvic canal in supporting the gut in humans

The human pelvic canal (true pelvis) functions to support the abdominopelvic organs and serves as a passageway for reproduction (females). Previous research suggests that these two functions work against each other with the expectation that the supportive role results in a narrower pelvic midplane, while fetal passage necessitates a larger opening. In this research, we examine how gut size relates to the size and shape of the true pelvis, which may have implications on how gut size can influence pelvic floor integrity. Pelves and in vivo gut volumes were measured from CT scans of 92 adults (48 female, 44 male). The true pelvis was measured at three obstetrical planes (inlet, midplane, outlet) using 11 3D landmarks. CT volumetry was used to obtain an individual’s gut size. Gut volume was compared to the pelvic planes using multiple regression to evaluate the relationship between gut size and the true pelvis. We find that, in males, larger gut sizes are associated with increased mediolateral canal dimensions at the inlet and midplane. In females, we find that larger gut sizes are associated with more medially-projecting ischial spines and an anteroposteriorly longer outlet. We hypothesize that the association of larger guts with increased canal width in males and increased outlet length in females are adaptations to create adequate space for the gut, while more medially projecting ischial spines reduce the risk of pelvic floor disorders in females, despite its possible spatial consequences for fetal passage.

CT Volumetry of Convoluted Objects—A Simple Method Using Volume Averaging

Accurate measurement of object volumes using computed tomography is often important but can be challenging, especially for finely convoluted objects with severe marginal blurring from volume averaging. We aimed to test the accuracy of a simple method for volumetry by constructing, scanning and analyzing a phantom object with these characteristics which consisted of a cluster of small lucite beads embedded in petroleum jelly. Our method involves drawing simple regions of interest containing the entirety of the object and a portion of the surrounding material and using its density, along with the densities of pure lucite and petroleum jelly and the slice thickness to calculate the volume of the object in each slice. Comparison of our results with the object’s true volume showed the technique to be highly accurate, irrespective of slice thickness, image noise, reconstruction planes, spatial resolution and variations in regions of interest. We conclude that the method can be easily used for accurate volumetry in clinical and research scans without the need for specialized volumetry computer programs.

Prevention of Liver Failure in Extended Hepatic Resection

Background. Postoperative failure is a major cause of adverse outcomes in extensive liver resection. Post-resection liver failure requires intensive, including extracorporeal, care. Issues in correcting liver failure warrant novel approaches to prevent severe cases.Materials and methods. A retrospective analysis of 228 various-extent liver resections included minor (55.7 %), major (26.8 %) and extended (17.5 %) operations for malignant, benign and parasitic liver lesions. The post-resection liver failure rate has ben graded according to ISGLS.Results and discussion. Postoperative hepatic failure developed in 58 (25.4 %) cases, including 5 of 127 minor (3.9 %) resections, 18 major (29.5 %) and 35 of 40 extended resections (87.5 %). Mild class A liver failures were reported in 12.3 %, and severe classes B and C — in 9.2 % and 3.9 % cases, respectively.CT volumetry in place of the number of resected segments is suggested as a criterion to grade the expected post-resection residual liver, with >70 % defining a minor, 36–70 % — major and 25–35 % — extended expected residual liver.A two-staged extended hepatic resection approach is proposed to reduce postoperative liver failure, with vascular radiology-guided right portal vein embolisation (RPVE) or associating liver partition and portal vein ligation (ALPPS) at stage 1.A comparison of extended hepatic resection outcomes (n = 40) showed a significantly higher rate and severity of liver failure in single- vs. two-staged operations (p < 0.05).Conclusion. Liver failure is a leading cause of death in major and extended hepatic resection. Preoperative CT volumetry allows a more accurate volumetric control of expected post-resection residual liver. Two-staged extended hepatic resection can reliably reduce the rate and severity of postoperative liver failure.

Accuracy of the end-expiratory lung volume measured by the modified nitrogen washout/washin technique: a bench study

Background The functional residual capacity (FRC) determines the oxygenating capacity of the lung and is heavily affected in the clinical context of the acute respiratory distress syndrome. Nitrogen-wash-in/wash-out methods have been used to measure FRC. These methods have rarely been validated against exactly known volumes. The aim of the study was to assess the accuracy and precision of the N2 washout/washin method in measuring FRC, by comparing it with set volumes in a lung simulator. Methods We conducted a diagnostic bench study in the Intensive Care Unit and Radiology Department of a tertiary hospital in Switzerland. Using a fully controllable high fidelity lung simulator (TestChest®), we set the functional residual capacity at 1500 ml, 2000 ml and 2500 ml and connected to the GE Carestation respirator, which includes the nitrogen washout/washin technique (INview™ tool). FRC was then set to vary by different levels of PEEP (5, 8, 12 and 15 cmH2O). The main outcome measures were bias and precision of the TestChest® when compared to the results from the washout/washin technique, according to the results of a Bland Altman Analysis. We verified our findings with volumetric computed tomography. Results One hundred and thirty-five nitrogen-wash-in/wash-out measurements were taken at three levels of FIO2 (0.4, 0.5, 0.6). The CT volumetry reproduced the set end-expiratory volumes at the Simulator with a bias of 4 ml. The nitrogen-wash-in/wash-out method had a bias of 603 ml with acceptable limits of agreement (95% CI 252 to − 953 ml). Changes were detected with a concordance rate of 97%. Conclusions We conclude that the TestChest® simulator is an accurate simulation tool, concerning the simulation of lung volumes. The nitrogen wash-in/wash out method correlated positively with FRC changes, despite a relatively large bias in absolute measurements. The reference volumes in the lung simulator verified with CT volumetry were very close to their expected values. The reason for the bias could not be determined.