Research Presentation Session: Abdominal Viscera & GI Tract

RPS 1801 - From guidelines to new approaches in liver tumour imaging

March 2, 09:30 - 11:00 CET

6 min
Moderator introduction
Maria Carmen Ayuso Colella, Barcelona / Spain
7 min
Alternative surveillance using CT/MR improves clinical outcomes in high-risk patients with chronic hepatitis B
Dong Ho Lee, Seoul / Korea, Republic of
Author Block: D. H. Lee; Seoul/KR
Purpose: This study aimed to evaluate the outcome of alternative hepatocellular carcinoma (HCC) surveillance using CT/MR compared to US only in chronic hepatitis B (CHB) patients.
Methods or Background: We enrolled consecutive CHB patients undergoing regular HCC surveillance, classifying into two groups: US only group and alternative surveillance group. The risk estimation for HCC in CHB (REACH-B) score was calculated to categorise high and low risk. Outcomes included 10-year overall survival (OS), size and Barcelona Clinic Liver Cancer (BCLC) stage of HCC, and OS after HCC diagnosis.
Results or Findings: A total of 2,024 patients were enrolled with 1,012 patients in each group. There was no significant difference in OS (96.0% in US only versus 96.8% in alternative surveillance; P=0.379). In both groups, HCC occurred in 66 patients. Medium size of HCC in the alternative surveillance was significantly smaller than US only (1.6 cm versus 2.1 cm; P<0.001). The rate of BCLC 0 stage HCC was also significantly higher in alternative surveillance than US only (71.2% [47/66] versus 42.4% [28/66]; P=0.003). OS after HCC diagnosis in the alternative surveillance group was significantly better than that in the US only group (83.0% versus 67.0%; P=0.025). In the high-risk group including 970 patients, alternative surveillance provided significantly better OS (97.3% versus 93.6%; P=0.029) and OS after HCC diagnosis (83.0% versus 60.6%; P=0.010) than US only. However, there was no significant difference in both OS (P=0.202) and OS after HCC diagnosis (P=0.937) in 1,054 patients with low risk.
Conclusion: Alternative surveillance using CT/MR enabled the detection of HCC at an earlier stage, with smaller size, than US only and had potential to improve OS after HCC diagnosis, especially for patients with high risk.
Limitations: The retrospective study design, prone to selection bias, was an identified limitation.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was designed as a single-centre retrospective cohort study and approved by the institutional review board of Seoul National University Hospital (spproval number: H-2208-023-1346) with the waiver of requirement of informed consent.
7 min
A comprehensive study on the feasibility and diagnostic potential of fluctuation imaging (FLI) in liver tumour assessment
Dong Ho Lee, Seoul / Korea, Republic of
Author Block: D. H. Lee, J. Y. Lee; Seoul/KR
Purpose: B-mode ultrasound (US) is commonly used for liver disease imaging, although it has limitations in characterising liver masses. This study aims to assess the clinical potential of a newly developed US technique called fluctuation imaging (FLI).
Methods or Background: In this prospective exploratory study, we enrolled 65 patients diagnosed with liver tumours based on histopathology or typical imaging findings. All participants underwent US examination, which included FLI. FLI involved capturing approximately 100 frames of images during a 10-second breath-holding period to generate a color-coded FLI map. The presence of fluctuation signals within liver tumours on the FLI map was noted: the presence of increased fluctuation signal was represented as a yellow to red colour within the tumour. We compared the incidence of increased fluctuation signals using the chi-square test.
Results or Findings: FLI map creation was successful in 95.4% of cases (62/65), with three cases failing due to respiratory motion. Among the 62 analysed patients, 38 had 42 haemangiomas (median size: 1.9 cm), 13 had hepatocellular carcinoma (median size: 2.6 cm), two had cholangiocarcinoma (2.6 and 4.5 cm), and one each had cortical adenoma from hepato-adrenal fusion (3.0 cm), malignant mesothelioma (4.5 cm), and angiomyolipoma (6.1 cm). The remaining six participants had seven metastases from colon cancer (median size: 2.3 cm). Among the 42 haemangiomas, 23 (54.8%) exhibited increased fluctuation signals on the FLI map. In contrast, only three out of 25 non-haemangioma liver tumours (12.0%) showed increased fluctuation signals (54.8% for haemangioma's versus 12.0% for non-haemangiomas, P=0.001).
Conclusion: The acquisition of FLI maps during liver US examinations proved to be feasible, and the identification of increased fluctuation signals on the FLI map may assist in detecting haemangiomas.
Limitations: The small number of participants was an identified limitation.
Funding for this study: Canon Medical Systems supported this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The institutional review board of Seoul National University Hospital approved this prospective study.
7 min
Comparison of diagnostic guidelines for hepatocellular carcinoma on gadoxetic acid-enhanced liver magnetic resonance imaging
Jeong-Hee Yoon, Seoul / Korea, Republic of
Author Block: J-H. Yoon, Y. K. Kim, W. Chang, J-I. Choi, B. J. Park, J-Y. Choi, H. S. Park, C. H. Lee, J. M. Lee; Seoul/KR
Purpose: Non-invasive diagnostic guidelines for HCC vary, especially regarding hepatobiliary agent-enhanced magnetic resonance imaging (HBA-MRI). We evaluated the diagnostic performance of four guidelines and readers’ judgment in diagnosing HCC using HBA-MRI in high-risk patients.
Methods or Background: This retrospective study included treatment-naive patients at risk of HCC who underwent HBA-MRI from January 2015 to June 2018. Four radiologists, using a pre-programmed algorithm on a web-based platform, independently reviewed focal liver lesions (FLLs) according to four guidelines: American Association for the Study of Liver Diseases/Liver Imaging Reporting and Data System (AASLD/LI-RADS), Korean Liver Cancer Association-National Cancer Center (KLCA-NCC), European Association for the Study of the Liver (EASL), Asian Pacific Association for the Study of the Liver (APASL). Readers’ judgment was also recorded. The guidelines’ diagnostic performance was compared in all patients and subgroups. Additionally, the diagnostic odds ratio (DOR) was assessed.
Results or Findings: We analysed 2,445 FLLs in 2,237 patients; 69.3% (1,694/2,445) were HCC. KLCA-NCC demonstrated the highest accuracy (80.0%), followed by APASL, AASLD/LI-RADS (77.8%, 76.4%), and EASL (75.1%). APASL exhibited the highest sensitivity (89.1%), followed by KLCA-NCC (78.2%), while AASLD/LI-RADS displayed the highest specificity (89.6%), followed by EASL (88.1%). The DORs were 20.7 for AASLD/LI-RADS, 18.9 for KLCA-NCC, 16.8 for EASL, and 8.9 for APASL. The readers’ judgment demonstrated higher accuracy than the guidelines (86.0%, P<0.001). In small (<20 mm) FLLs, Eastern guidelines showed higher accuracy than Western guidelines (P<0.001). Diagnostic accuracy of guidelines was 71.8%–79.5% in cirrhosis and 75.2%–82.3% in chronic hepatitis B without cirrhosis.
Conclusion: Eastern guidelines demonstrated high sensitivity, while Western guidelines displayed high specificity. KLCA-NCC achieved the highest accuracy, and AASLD/LI-RADS exhibited the highest DOR.
Limitations: The retrospective design inevitably introduced bias which we attempted to minimise by including a large population.
Funding for this study: This work is financially supported by Bayer.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Institutional Review Board of Seoul National University Hospital and participating institutions.
7 min
Diagnostic performance of CT/MRI LI-RADS v2018 in non-cirrhotic steatotic liver disease
Justin Ruey Tse, Stanford / United States
Author Block: J. Cao, A. Shon, L. S. Yoon, J. R. Tse; Stanford, CA/US
Purpose: A substantial proportion of patients with steatotic liver disease (SLD) develop hepatocellular carcinoma (HCC) without cirrhosis. Our purpose was to assess the diagnostic performance of CT/MRI LI-RADS v2018 (LI-RADS) among patients with non-cirrhotic SLD.
Methods or Background: This IRB-approved, retrospective, single-centre study included 103 observations with histopathologic correlation from 77 adult patients who underwent liver CT/MRI from 2010-2023. All patients had histopathologic evidence of SLD without cirrhosis. Three board-certified abdominal radiologists (R1-R3) blinded to the tissue diagnoses assessed each observation by LI-RADS criteria and assigned a final category. Inter-reader agreements were assessed with Cohen’s kappa. The positive predictive value (PPV), sensitivity, specificity, and accuracy of identifying HCC and overall malignancy were calculated.
Results or Findings: Of 103 observations, 59 (57%) were benign and 44 (43%) were malignant. PPV for HCC was 0-0% for LR-1, 0-0% for LR-2, 0-11% for LR-3, 13-22% for LR-4, 75-88% for LR-5, 0-8% for LR-M, and 50-75% for LR-TIV. For malignancy (including HCC), PPV was 0-0% for LR-1, 0-12% for LR-2, 5-12% for LR-3, 19-33% for LR-4, 78-88% for LR-5, 65-91% for LR-M, and 100-100% for LR-TIV. For LR-5 in detecting HCC, sensitivity was 83%, 79%, 83% (R1-3, respectively), specificity was 89%, 96%, 92%, and accuracy was 87%, 91%, and 89%. For composite categories of LR-5, LR-M, or LR-TIV in detecting overall malignancy, sensitivity was 89%, 89%, and 86%, specificity was 86%, 95%, and 81%, and accuracy was 87%, 92%, and 84% respectively. Most common false positives for LR-5 were due to hepatocellular adenomas. Inter-reader agreements for major features ranged from 0.660-0.833 and was 0.751 for the final category.
Conclusion: CT/MRI LI-RADS v2018 can be applied to non-cirrhotic SLD patients with high but imperfect specificity.
Limitations: This was a single-centre, retrospective study with selection bias of histologically-proven observations.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study was approved by the university Institutional Review Board
7 min
Value of preoperative magnetic resonance imaging for diagnosis of LR‑3 and LR-4 lesions coexisting with main hepatocellular carcinoma
Yuyao Xiao, Shanghai / China
Author Block: Y. Xiao, C. Yang, M. Zeng; Shanghai/CN
Purpose: The diagnostic performance of magnetic resonance imaging (MRI) features favouring hepatocellular carcinoma (HCC) in LR-3 and LR-4 observations in high-risk patients have been evaluated in previous studies. Our objective was to explore which preoperative clinical data and conventional MRI findings may indicate the presence of HCC in LR-3 and LR-4 lesions of HCC patients.
Methods or Background: In this study, we enrolled 102 patients with histopathologically confirmed HCC coexisting with 110 LR-3 and LR-4 lesions (HCCs group [n = 66], non-HCCs group [n = 44]). Two radiologists retrospectively assessed the preoperative MRI features, and each lesion was assigned according to LI-RADS. Preoperative clinical data were also evaluated. Logistic regression analyses were used to assess the relative value of these parameters as potential predictors of HCC.
Results or Findings: On multivariate analysis, the presence of restricted diffusion (OR: 18.590, p<0.001), delayed enhancement (OR: 0.113, p<0.001), and T2WI mild-moderate hyperintensity (OR: 3.084, p=0.048) were found to be independent predictors for HCC diagnosis. The sensitivity and specificity of the above independent variables and their combination for the diagnosis of HCC ranged from 47.0–80.3% and 56.8–97.7%, respectively. Combining these three findings for the prediction of HCC resulted in a specificity greater than 97%, and the AUC further increased to 0.874.
Conclusion: The presence of restricted diffusion, delayed enhancement, and T2WI mild-moderate hyperintensity can be useful features in risk stratifying coexisting LR-3 and LR-4 lesions in HCC patients.
Limitations: Firstly, this was a single-centre retrospective study lacking longitudinal data. Secondly, the number of LR-4 lesions was also relatively small in our study, so our results might not represent the true spectrum of LR-3 and LR-4 observations in HCC patients.
Funding for this study: This study received funding from the National Natural Science Foundation of China (grant number: 82171897, 82272078).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This retrospective study was approved by the local Ethics Committee, and written informed consent was waived due to its retrospective design.
7 min
A new criterion for diagnosis of subcentimetre hepatocellular carcinoma in treatment-naive patients using tumour biomarker and gadoxetic acid-enhanced MRI features
Peng Huang, Shanghai / China
Author Block: P. Huang, F. Wu, C. Wang, Y. Xiao, G. Miao, C. Yang, M. Zeng; Shanghai/CN
Purpose: Based on imaging findings, current diagnostic criteria for subcentimetre hepatocellular carcinoma (HCC) have suboptimal diagnostic performances. The aim of the present study is to develop a diagnostic nomogram including gadoxetic acid-enhanced MRI features and tumour biomarkers.
Methods or Background: This study enrolled treatment-naive patients with chronic hepatitis B who had a solitary subcentimetre observation from April 2016 to March 2023. The final diagnosis was confirmed by pathology for HCC and pathology or follow-up for non-HCC controls. Logistic regression analysis for imaging features and tumour biomarkers was used to identify independent predictors associated with HCC that were then incorporated into the nomogram. Diagnostic performances of the new criterion were compared to wash-in and -out.
Results or Findings: A total of 224 patients (116 with HCC and 108 with non-HCC) were divided into a training cohort (including 155 patients) and temporal validation cohort (including 69 patients). The factors associated with HCC diagnosis were alpha-fetoprotein >20 ng/mL or des-gamma-carboxy prothrombin >40 IU/mL, T2WI mild-moderate hyperintensity, arterial-phase hyperenhancement, portal-phase washout, and transitional-phase hypointensity. Incorporating these 5 factors, the nomogram achieved good concordance indexes of 0.92 and 0.95 in diagnosing subcentimetre HCC in the training and temporal validation cohorts, respectively, and had well-fitted calibration curves. Using a nomogram score of 296 as a cut-off, the new criterion yielded higher sensitivity than wash-in and -out (training cohort: 72.0% versus 51.2%, P<0.001; validation cohort, 79.4% versus 47.1%, P<0.001) without a significant decrease in specificity (training cohort: 90.4% versus 91.8%, P>0.999; validation cohort, 91.4% versus 91.4%, P>0.999).
Conclusion: Including tumour biomarkers in the diagnostic algorithm may improve the diagnostic performance for subcentimetre HCC.
Limitations: Our results may be limited in their generalisability, especially in regions other than HBV-endemic areas.
Funding for this study: Funding was received from The Clinical Research Plan of SHDC (number: SHDC2020CR1029B), National Natural Science Foundation of China (number: 82171897), and National Natural Science Foundation of China (number: 82371923).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The institutional review board of Zhongshan Hospital, Fudan University (number: B2020-372R) approved this study.
7 min
Quantitative CT analysis of hepatocellular carcinoma nodules in liver transplant candidates: impact of volume of interest and contrast phase on recurrence prediction
Francesco Rizzetto, Rho / Italy
Author Block: F. Rizzetto, R. Manzini, L. Centonze, C. B. Monti, S. Garziano, J. Di Napoli, L. A. Carbonaro, A. Vanzulli; Milan/IT
Purpose: To evaluate how different lesion volumes-of-interest (VOIs) and contrast phases affect quantitative CT analysis of hepatocellular carcinoma (HCC) in liver transplant candidates.
Methods or Background: Liver transplant candidates from 2010 to 2019, with waitlist placement CT showing suspicious HCC nodules (LI-RADS=4-5) and no treatment, were retrospectively included. HCC nodules, with or without a peritumoural region of 5, 10, and 15 mm, and "background" liver parenchyma were contoured across arterial, venous, and delayed phases. Radiomic features (RFs), both directly extracted from segmentations and normalised for "background" parenchyma, were computed and compared for inter-VOIs and inter-phase relative change (RC), and autocorrelation using Spearman’s rho. RFs with RC<10% and rho>0.9 were considered redundant. Non-redundant RFs with different distribution in patients with and without post-transplant recurrence were selected to build multiple logistic regression models. Predictive capability for post-transplant recurrence was assessed comparing areas under the curve (AUC) from receiver operating characteristic analysis.
Results or Findings: The CT scans of 53 patients were selected, for a total of 1,260 segmentations from 105 nodules, with eight (15%) recurrence cases. Changing VOIs and phases, the number of redundant RFs was 14-26% and 16-34%, respectively, while 4% of RFs were autocorrelated. Selected non-redundant RFs allowed the building of eight predictive models (pseudo-r2=0.13-0.46), each comprising 5-12 RFs, with AUC ranging from 0.77 to 90 (p<0.02). Best performance was achieved when segmenting HCC nodules with or without 5 mm of peritumoural region in arterial phase. Venous and delayed phases showed predictive capability only for segmentations including 10-15 mm of peritumoural region after normalisation for background parenchyma.
Conclusion: Selection of optimal VOI and contrast phase combination is critical to maximize post liver transplant HCC recurrence prediction using quantitative CT imaging.
Limitations: The retrospective single-centre design and the limited sample size are the main limitations of the study.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The local ethics committee approved the retrospective data collection in an anonymous, aggregated form.
7 min
Development of the MIEM score to predict survival after recurrence in patients with recurrent HCC following curative resection
Hong Wei, Chengdu / China
Author Block: H. Wei, B. Song; Chengdu/CN
Purpose: This study aimed to create a predictive score for survival after recurrence (SAR) based on MRI features and clinical-pathological characteristics in patients with recurrent HCC following initial curative resection.
Methods or Background: This single-centre, retrospective study included consecutive patients who underwent contrast-enhanced MRI within one month before curative resection for primary HCC and developed recurrence during follow-up from December 2011 to June 2021. Clinical (i.e. age, sex, aetiology, BCLC stage, and AFP level), pathological (i.e. tumour differentiation, microvascular invasion, liver capsule invasion, and cirrhosis), and recurrence-related data (i.e. adjuvant therapy, early versus late recurrence, and intrahepatic versus extrahepatic recurrence) were collected. MRI images were independently reviewed by two radiologists in terms of all LI-RADS version 2018 imaging features and several non-LI-RADS imaging features. Uni- and multivariable Cox regression analyses were used to identify variables associated with SAR. A regression-based predictive model was constructed with five-fold cross-validation.
Results or Findings: A total of 151 patients with recurrent HCC were included (median age, 53 years; 135 men). During a median follow-up period of 55 months, 31% (47/151) of patients experienced death. Predictors for SAR included non-smooth tumour margin (hazard ratio [HR] =4.6), rim arterial phase hyperenhancement (HR=1.9), extrahepatic recurrence (HR=1.9), and male sex (HR=0.5). By incorporating the above predictors, the MIEM score demonstrated a C-index of 0.71 (95% confidence interval: 0.64, 0.79). Using 11 as the threshold of the MIEM score, all patients were categorised into prognostically distinct low- and high-risk groups (P<0.001).
Conclusion: The MIEM score may serve as a useful tool to help predict SAR for patients with recurrent HCC following hepatectomy.
Limitations: The single-centre nature of the study, the retrospective study design, and lack of external validation were identified as limitations.
Funding for this study: This work was supported by the National Natural Science Foundation of China (grant number: U22A20343).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: This study was approved by the Biomedical Ethics Review Committee of West China Hospital, Sichuan University (approval number: 2022-651). The requirement for informed consent was waived (due to the retrospective design) by the Biomedical Ethics Review Committee of West China Hospital, Sichuan University.
7 min
Nomogram development and validation based on Gd-EOB-DTPA-enhanced MRI to predict IDH1 mutation for intrahepatic cholangiocarcinoma
Xiaoqi Zhou, Guangzhou / China
Author Block: X. Zhou, M. Chen, D. Xu, S-T. Feng; Guangzhou/CN
Purpose: Isocitrate dehydrogenase 1 (IDH1) mutation inhibitors show promise for targeted therapy in intrahepatic cholangiocarcinoma (ICC), but only for IDH1 mutated tumours. The purpose of this study is to establish and validate a model to predict IDH1 gene mutation in ICC based on preoperative Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) images.
Methods or Background: A total of 85 ICCs were randomly assigned to the training set (n=59) and the test set (n=26). Next generation sequencing and immunohistochemical analysis were performed for IDH1 mutation status. Preoperative imaging features of Gd-EOB-DTPA-enhanced MRI were qualitatively and quantitatively reviewed by two radiologists. Nomograms were developed based on the significant variables for differentiating the IDH1-mutated and IDH1-unmutated ICCs in the training sets.
Results or Findings: The IDH1 mutation rate was 20% (17/85). After filtering the factors (p<0.1) based on univariate analysis, the serum AFP value (p=0.17), intratumoural vessel (p=0.01), location of liver lobe (p=0.14), T1 change ratio (p=0.004), T2 central brightness (p=0.01) and ADC value (p=0.008) were incorporated into the nomogram for predicting IDH1-mutated ICCs. Combing all six significant variables provided a diagnostic accuracy of 88%, sensitivity of 75%, and a specificity of 90% for identifying IDH1 mutation status in the test set. The area under the receiver operating characteristic curve value of the logistical regression coefficient-based nomogram was 0.927 (95% confidence intervals, 0.838-1.000) and 0.881 (95% confidence intervals, 0.690-1.000) for the training and test sets. The nomogram exhibited good calibration and clinical usefulness.
Conclusion: Gd-EOB-DTPA-enhanced MRI-based nomogram effectively predicts IDH1 mutation status in ICCs and may assist clinicians in pretreatment decisions.
Limitations: Firstly, this is a retrospective study with potential patient selection bias. Secondly, this was a single-centre study with a small sample size.
Funding for this study: Funding was received from the National Natural Science Foundation of China (82271958, 81971684).
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study was approved by the institutional review board and ethical committee of Sun Yat-sen University.
7 min
Prognostic role of CT and MRI of resectable intrahepatic mass forming cholangiocarcinoma
Silvia De Vizio, Rome / Italy
Author Block: S. De Vizio, E. Genco, F. M. Sessa, M. G. Brizi, E. Panettieri, F. Giuliante, E. Sala; Rome/IT
Purpose: Imaging is crucial for diagnosis as well as for prognosis of intrahepatic mass forming cholangiocarcinoma. In the last decade some studies focused on diffusion weighted imaging (MRI) and arterial enhancement's (CT and MRI) role in prognosis stratification of resectable intrahepatic cholangiocarcinoma. The aim of this retrospective study was to evaluate the best prognostic imaging biomarkers for resectable intrahepatic mass forming cholangiocarcinomas.
Methods or Background: We retrospectively evaluated 123 patients with histologically proven intrahepatic cholangiocarcinoma, surgically treated in our university hospital from 2010 to 2022.
Patients were divided in two groups: a multiphasic contrast-enhanced CT group and a multiphasic hepato-specific contrast-enhanced MR-DWI group. Each group was further divided into resectable lesion and unresectable lesion sub-groups.
The percentage of arterial enhancement at CT and MR was categorised as hypervascular (>50% of the lesion), peripherally enhancing (10-50%), or hypovascular (<10%); DWI was qualitatively evaluated on ADC maps and lesions graded as diffusion restriction (<1/3 of the lesion) and diffusion restriction (>1/3).
Analysis was performed by two expert readers.
Overall survival at 1-year and 3-years was assessed by Kaplan-Meyer curves whose differences were analysed by Cox analysis.
Results or Findings: A total of 26 patients were included in the MRI group (6 hypervascular, 14 peripheral, 6 hypovascular), and 35 in the CT group (7 hypervascular, 11 peripheral, 17 hypovascular); 62 patients were excluded because of poor quality of arterial phase and/or DWI images.
In both groups overall survival at 1-year was higher for the hypervascular group compared to the hypovascular group (87.3% versus 26.2%).
In the MRI group, 1-year survival was higher in the subgroup with diffusion restriction of <1/3 of the lesion.
At Cox proportional hazards model analysis, hypervascularity was associated with a better overall survival.
Conclusion: CT/MR hypervascularity and lower extent of diffusion restriction are both positive prognostic biomarkers.
Limitations: The retrospective study design was an identified limitation.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: No information provided by the submitter.
7 min
Photon-counting detector CT for liver lesion detection: optimising virtual monoenergetic images across different sizes and doses
Andre Euler, Baden / Switzerland
Author Block: D. Racine1, V. Mergen2, A. Viry1, T. Frauenfelder2, H. Alkadhi2, V. Vitzthum1, A. Euler3; 1Lausanne/CH, 2Zurich/CH, 3Baden/CH
Purpose: To evaluate the optimal energy level of virtual monoenergetic images (VMI) from photon-counting detector CT (PCD-CT) for the detection of liver lesions as a function of phantom size and radiation dose.
Methods or Background: An anthropomorphic abdominal phantom with liver parenchyma and lesions was imaged on a dual-source PCD-CT at 120 kVp. The lesions were hypo- or hyperattenuating and had diameters of 5-10 mm. Rings of fat-equivalent material were added to emulate medium- or large-sized patients. The medium size was imaged at 5, 2.5, and 1.25 mGy and the large size at 5 and 2.5 mGy, respectively. Each setup was imaged ten times. For each setup, VMIs from 40 to 80 keV at 5 keV increments were reconstructed with quantum iterative reconstruction at a strength level of 4 (QIR-4). Lesion detectability was measured as area under the receiver operating curve (AUC) using a channelised hotelling model observer with ten dense differences of Gaussian channels.
Results or Findings: Overall, highest detectability was found at 65 and 70 keV for both hypo- and hyperattenuating lesions in the medium and large phantom, independent of radiation dose (AUC range: 0.910-0.999 for the medium and 0.935-0.987 for the large phantom, respectively). Lowest detectability was found at 40 keV irrespective of the radiation dose and phantom size (AUC range: 0.784-0.993). Reducing radiation dose decreased lesion detectability more strongly at 40-50 keV as compared with 65-75 keV. At equal radiation dose, detection as a function of VMI energy differed more strongly for the large size as compared with the medium size phantom (12 % versus 6 %).
Conclusion: Detectability of hypo- and hyperattenuating liver lesions differed between VMI energies for different phantom sizes and radiation doses. VMI at 65 and 70 keV yielded highest detectability, independent of phantom size and radiation dose.
Limitations: The phantom study design was an identified limitation.
Funding for this study: No funding was received for this study.
Has your study been approved by an ethics committee? Not applicable
Ethics committee - additional information: Ethics committee approval was not needed because of the design as a phantom study.
7 min
Detection of spoke-wheel pattern in focal nodular hyperplasia with microvascular flow imaging in a preliminary study
Aladár David Rónaszéki, Gyömrő / Hungary
Author Block: B. Zsély, A. D. Rónaszéki, B. K. Budai, R. Surendranath, R. Stollmayer, Z. Zsombor, G. Györi, P. Maurovich-Horvat, P. N. Kaposi; Budapest/HU
Purpose: Microvascular flow imaging (MVFI) is a novel Doppler ultrasound (US) technique to detect slow flow in capillary vessels. The spoke-wheel vascularity pattern is characteristic of focal nodular hyperplasia (FNH), and it is consistently detectable with MVFI. The identification of the typical patterns of vascularity, including the spoke-wheel pattern with MVFI can expedite diagnosis, spare patients from unnecessary procedures, and reduce costs.
Methods or Background: This study retrospectively collected MVFI US images of 50 patients followed for known focal liver lesions (FLL). The lesions were diagnosed by contrast-enhanced ultrasound (CEUS), biopsy, or magnetic resonance imaging (MRI) with a liver-specific contrast agent. Patients were examined using a Samsung RS85 Prestige scanner. The vascularity of the lesions was evaluated with either conventional colour Doppler US or directional power Doppler imaging using the S-FlowTM application. We used the MV-FlowTM application for microvascular flow imaging by recording a 5-10 second-long video in a breath-hold.
The Wilk test was used to check the normality of the data. Continuous variables were analysed with the Mann-Whitney U-test, categorical variables with Fisher’s exact test, and chi-square test. A logistic regression analysis was performed with the individual morphological characteristics, the variables were characterised by odds ratio (OR) value, sensitivity, and specificity.
Results or Findings: The study patients included 21 FNHs, 7 haemangiomas, 9 hepatocellular carcinomas (HCC), and 13 liver metastases. The spoke-wheel pattern detectable with MVFI was detected in a higher number in cases of FNHs (OR>100 [95% CI: 45.365 - Inf]; p<0.001), which proved to be specific (1.0) and showed high sensitivity (0.955).
Conclusion: Our preliminary results show the spoke-wheel pattern can be easily detected with MVFI, even in the case of small FNHs, whose vascularisation pattern can help distinguish them from other FLLs.
Limitations: The retrospective study design was an identified limitation.
Funding for this study: The authors received no funding for this study.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: The study has been approved by the institutional ethics committee of our university (SE-RKEB 140/2020).

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