Diagnostic Performance of Attenuation to Stage Liver Steatosis with MRI Proton Density Fat Fraction as Reference: A Prospective Comparison of Three US Machines.

Background US tools to quantify liver fat content have recently been made clinically available by different vendors, but comparative data on their accuracy are lacking. Purpose To compare the diagnostic performances of the attenuation parameters of US machines from three different manufacturers (vendors 1, 2, and 3) in participants who underwent liver fat quantification with the MRI-derived proton density fat fraction (PDFF). Materials and Methods From July 2020 to June 2021, consecutive participants with chronic liver disease were enrolled in this prospective single-center study and underwent MRI PDFF quantification (reference standard) and US on the same day. US was performed with two different machines from among three vendors assessed. Areas under the receiver operating characteristic curve (AUCs) for the staging of liver steatosis (MRI PDFF: ≥5.5% for grade ≥S1 and ≥15.5% for grade ≥S2) were calculated in test and validation samples and then compared between vendors in the study sample. Results A total of 534 participants (mean age, 60 years ± 13 [SD]; 320 men) were evaluated. Failure of measurements occurred in less than 1% of participants for all vendors. Correlation coefficients with the MRI PDFF were 0.71, 0.73, and 0.54 for the attenuation coefficients of vendors 1, 2, and 3, respectively. In the test sample, AUCs for diagnosis of steatosis grade S1 and higher and grade S2 and higher were 0.89 and 0.93 for vendor 1 attenuation, 0.88 and 0.92 for vendor 2 attenuation, and 0.79 and 0.79 for vendor 3 attenuation, respectively. In the validation sample, a threshold value of 0.65 for vendor 1 and 0.66 for vendor 2 yielded sensitivity of 77% and 84% and specificity of 78% and 85%, respectively, for diagnosis of grade S1 and higher. Vendor 2 attenuation had greater AUCs than vendor 3 attenuation (P = .001 and P = .003) for diagnosis of grade S1 and higher and grade S2 and higher, respectively, and vender 2 had greater AUCs for attenuation than vendor 1 for diagnosis of grade S2 and higher (P = .04). For all vendors, attenuation was not associated with liver stiffness (correlation coefficients <0.05). Conclusion To stage liver steatosis, attenuation coefficient accuracy varied among US devices across vendors when using MRI proton density fat fraction quantification as the reference standard, with some demonstrating excellent diagnostic performance and similar cutoff values. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Dubinsky in this issue.

Learning curve of liver stiffness measurement using a new hybrid machine composed of transient elastography interfaced with ultrasound.

OBJECTIVES: To assess the learning curve for performing reliable liver stiffness measurements using a new hybrid machine composed of transient elastography (TE) interfaced with an ultrasound device for radiographers and radiologists with different levels of expertise in ultrasound imaging. METHODS: Ten novice operators who had never performed TE measurements were prospectively evaluated from April to October 2018: senior radiologists, young radiologists, fellows, radiographers, and residents, with different levels of experience in abdominal ultrasound imaging. All operators had a short theoretical training followed by a training session under supervision in three patients. Then, each operator had to perform TE in 50 consecutive patients with chronic liver disease, using beforehand ultrasound examination to select measurement area in the right liver lobe, and if needed, the XL probe. Percentages of failures and reliable measurements were compared. RESULTS: The rates of failures of measurements, poorly reliable, reliable, and very reliable results, were of 4.2% (21/500), 2.4% (12/500), 47.6% (238/500), and 45.8% (229/500), respectively. The rates of reliable plus very reliable results were excellent, ranging from 91 to 96% among all the subgroups. The rates of very reliable, reliable, and unreliable results did not differ between operator subgroups and especially between junior radiologists, senior radiologists, and radiographers. No breaking point was observed in the interquartile range/median values over time. CONCLUSION: TE interfaced with ultrasound in this hybrid machine presents no learning curve effect. After a short initial training session, a novice observer is able to perform high rates of reliable and very reliable TE measurements. KEY POINTS: • When performing liver stiffness measurements using a new hybrid machine composed of transient elastography interfaced with ultrasound, the rate of failures of measurements is very low, below 5%. • After a short training session and using ultrasound planning, a novice operator, whatever its expertise in ultrasound imaging, is capable of performing high rates of reliable and very reliable measurements. • No learning curve is needed for performing reliable liver stiffness measurements using this new hybrid machine.

Software-based assessment of tumor margins after percutaneous thermal ablation of liver tumors: A systematic review.

PURPOSE: The purpose of this study was to make a systematic review of clinical studies evaluating software-based tumor margin assessment after percutaneous thermoablation (PTA) of liver tumors. MATERIALS AND METHODS: A systematic literature search was performed through Pubmed/MEDLINE, Embase and the Cochrane Library. Original studies published in English that reported on software-based assessment of ablation margins (AM) following PTA of liver tumors were selected. Studies were analyzed with respect to design, number of patients and tumors, tumor type, PTA technique, tumor size, target registration error, study outcome(s) (subtypes: feasibility, comparative, clinical impact, predictive or survival), and follow-up period. RESULTS: Twenty-nine articles (one multi-center and two prospective studies) were included. The majority were feasibility (26/29, 89.7%) or predictive (23/29, 79.3%) studies. AM was a risk factor of local tumor progression (LTP) in 25 studies (25/29, 86.2%). In nine studies (9/29, 31%) visual assessment overestimated AM compared with software-aided assessment. LTP occurred at the location of the thinnest margin in nine studies (9/29, 31%). Time for registration and analysis was heterogeneously reported, ranging between 5-30 min. Mean target registration error was reported in seven studies (7/29, 24.1%) at 1.62 mm (range: 1.20-2.23 mm). Inter-operator reproducibility was high (kappa range: 0.686-1). Ascites, liver deformation and inconspicuous tumor were major factors of co-registration error. CONCLUSION: Available studies present a low level of evidence overall, since most of them are feasibility, retrospective and single-center studies.

Inter-platform Variability of Liver Elastography: Pairwise Comparisons of Four Devices.

This study was aimed at determining whether liver stiffness measurements by 2-D shear wave elastography using GE's (2D-SWE-GE) and Canon's (2D-SWE-Canon) newest apparatus and vibration-controlled transient elastography (VCTE) share the same distribution of values compared with Hologic Supersonic Imagine (2D-SWE-SSI). In participants with chronic liver disease recruited in two university centers from August 2020 to February 2021, liver stiffness was measured the same day by the same operator with 2D-SWE-SSI plus one of the following devices: 2D-SWE-GE (n = 314), 2D-SWE-Canon (n = 311), and VCTE-M probe (n = 812). VCTE-M and 2D-SWE-SSI values shared the highest correlation and concordance coefficients (0.933 and 0.920, respectively) and a coefficient of variation below 20%, whatever the range of values. 2D-SWE-GE had the lowest variations, with 2D-SWE-SSI values below 13 kPa. However, both 2D-SWE-GE and 2D-SWE-Canon exhibited a frank underestimation of the high percentiles' 2D-SWE-SSI values with coefficients of variation of -21.7% and -25.8% from 13- to 17-kPa values, and -44.3% and -32.4% from 17-kPa values, respectively. In conclusion, knowledge of the vendor-specific distribution of values is mandatory for interpreting results obtained with different machines. If all four techniques behave closely in low values allowing excluding advanced chronic liver diseases in larger populations, discrepancies are observed in high percentile values.

Liver venous deprivation versus portal vein embolization before major hepatectomy: future liver remnant volumetric and functional changes.

BACKGROUND: We previously showed that embolization of portal inflow and hepatic vein (HV) outflow (liver venous deprivation, LVD) promotes future liver remnant (FLR) volume (FLR-V) and function (FLR-F) gain. Here, we compared FLR-V and FLR-F changes after portal vein embolization (PVE) and LVD. METHODS: This study included all patients referred for liver preparation before major hepatectomy over 26 months. Exclusion criteria were: unavailable baseline/follow-up imaging, cirrhosis, Klatskin tumor, two-stage hepatectomy. 99mTc-mebrofenin SPECT-CT was performed at baseline and at day 7, 14 and 21 after PVE or LVD. FLR-V and FLR-F variations were compared using multivariate generalized linear mixed models (joint modelling) with/without missing data imputation. RESULTS: Baseline FLR-F was lower in the LVD (n=29) than PVE group (n=22) (P<0.001). Technical success was 100% in both groups without any major complication. Changes in FLR-V at day 14 and 21 (+14.2% vs. +50%, P=0.002; and +18.6% vs. +52.6%, P=0.001), and in FLR-F at day 7, 14 and 21 (+23.1% vs. +54.3%, P=0.02; +17.6% vs. +56.1%, P=0.006; and +29.8% vs. +63.9%, P<0.001) differed between PVE and LVD group. LVD (P=0.009), age (P=0.027) and baseline FLR-V (P=0.001) independently predicted FLR-V variations, whereas only LVD (P=0.01) predicted FLR-F changes. After missing data handling, LVD remained an independent predictor of FLR-V and FLR-F variations. CONCLUSIONS: LVD is safe and provides greater FLR-V and FLR-F increase than PVE. These results are now evaluated in the HYPERLIV-01 multicenter randomized trial.

Transarterial Chemoembolization of Hepatocellular Carcinoma with Idarubicin-Loaded Tandem Drug-Eluting Embolics.

: Objective: To describe the responses, toxicities and outcomes of HCC patients treated by transarterial chemoembolization (TACE) using idarubicin-loaded TANDEM beads. Materials and Methods: Seventy-two consecutive patients (mean age: 71 years (58-84 years)) with HCC were treated by TACE using idarubicin-loaded TANDEM in a first line, over a five-year period. Most patients (89%) had liver cirrhosis classified as Child-Pugh A (90%). BCLC B classification applied in 85% of cases. Baseline tumor burden was limited to one to three nodules in 92% of cases, unilobar in 88% cases, with a median tumor diameter of 55 mm (range: 13-150 mm). Toxicity was assessed using NCI CTC AE v4.0. Response was assessed using mRECIST criteria. Time-to-treatment failure (TTTF) and overall survival (OS) were also calculated based on Kaplan-Meier method. Result: Of 141 TACE sessions performed with bead sizes of 100 and 75 µm in 42 (29.8%) and 99 (70.2%) sessions, respectively. In 78% of all TACE sessions, the full dose of idarubicin-loaded beads was injected. Grade 3-4 AE were observed after 73 (52%) sessions, most of them being biological. Multi-organ failure was observed three days after the first TACE in a Child B patients, unfortunately leading to death. Overall, the best objective response rate (ORR) was 65%. Median follow-up lasted 14.3 months (95% CI: 11.2-18.8 months). Median TTTF and OS were 14.4 months (95% CI: 7.2-24.6 months) and 34.6 months (95% CI: 24.7-not reached) respectively. Conclusion: In this retrospective study involving well-selected HCC patients, high ORR and long TTTF and OS are observed after TACE using idarubicin-loaded TANDEM. A randomized trial is needed.

Radiation Exposure During Transarterial Chemoembolization: Angio-CT Versus Cone-Beam CT.

INTRODUCTION: Cone-beam computed tomography (CBCT) has been developed to improve reliability of many interventional radiology (IR) procedures performed with Angio system, such as transarterial chemoembolization (TACE). Angio-CT has emerged as a new imaging technology that combines a CT scanner with an Angio system in the same IR suite. The purpose of our study was to compare Angio system with CBCT capability and Angio-CT in terms of patient radiation exposure during TACE procedures. MATERIALS AND METHODS: Consecutive TACE procedures performed between January 2016 and September 2017 with the two imaging modalities (Artis Zeego defining the CBCT group and Infinix-i 4D-CT defining the Angio-CT group) were reviewed. TACE and patient's characteristics and patient radiation exposure parameters were collected. Dose-area products (DAP) and dose-length products (DLP) were converted into effective doses (ED) using conversion factors. Accuracy of tumor targeting and response was retrospectively assessed. RESULTS: A total of 114 TACE procedures in 96 patients were included with 57 procedures in each group. The total ED in the Angio-CT group was 2.5 times lower than that in the CBCT group (median 15.4 vs. 39.2 mSv, p < 0.001). Both 2D ED and 3D ED were lower in the Angio-CT group than in the CBCT group (5.1 vs. 20 mSv, p < 0.001, and 7.4 vs. 17.9 mSv, p < 0.001, respectively). There was no significant difference neither in terms of classes of tumor targeting (p = 0.509) nor in terms of classes of tumor response (p = 0.070) between both groups. CONCLUSION: Angio-CT provides significant decrease in patient effective dose during TACE procedures compared to Angio system with CBCT.