Background: Hereditary hemorrhagic telangiectasia (HHT) is marked by arteriovenous fusion comprising hepatic vascular malformations (HVaMs) with the chance of bleeding. Aims: We investigated HVaMs in HHT patients by combination of contrast-enhanced ultrasound (CEUS) with perfusion imaging quantification to be able to sub-classify a high risk cohort of asymptomatic HHT patients. Methods: The imaging characteristics on CEUS in 34 patients (aged 21–84 years; mean 58.9) with HHT were retrospectively evaluated. Real-time contrast harmonic imaging, sulfur hexafluoride-filled microbubbles and motion adjustment were utilized. Cine loops of the liver were digital stored, perfusion was quantified using a software reading DICOM data`s. Results: HVaMs were diagnosed in 31 out of 34 patients. Significant uppermost peak enhancement (PE), wash-in area under the curve (WiAUC) and wash-in perfusion index (WiPI) were identified in the shunt region (100%), next in the hilar region (PE 32.6%; WiAUC 33.9%; WiPI 34.1%), and the lowest in the hepatic parenchyma (PE 10.2%; WiAUC 12.0%; WiPI 9.5%). The perfusion parameters in the shunt region compared to the other regions were significantly increased in one subgroup of patients. Consistent with this, the intrahepatic portal vein diameter and Buscarini grading was significantly higher, while portal vein peak velocity was significantly lower in this patient subset. By statistical analysis, we could correlate PE and WiPI to these clinical parameters, while WiAUC showed no clinical association. Conclusions: For the first time we combined CEUS findings with motion adjustment software to quantitative determine perfusion parameters of a cohort of HHT patients. Hereby, we could identify a subset of HHT patients with two markedly increased parameter values in the shunt region compared to the hilus/hepatic parenchyma. This could contribute to sub-classify a high-risk group of HHT patients with therapeutic indication.
Keywords: Research Article; Biology and life sciences; Anatomy; Cardiovascular anatomy; Blood vessels; Veins; Portal veins; Medicine and health sciences; Diagnostic medicine; Diagnostic radiology; Ultrasound imaging; Research and analysis methods; Imaging techniques; Radiology and imaging; Magnetic resonance imaging; Mathematical and statistical techniques; Statistical methods; Regression analysis; Physical sciences; Mathematics; Statistics; Gastroenterology and hepatology; Liver diseases; Portal hypertension; Physiology; Cardiovascular physiology; Blood circulation; Microcirculation; Arteries
Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominantly transmitted disorder affecting small mucocutaneous blood vessels and/or the vasculature of various viscera [[
Hepatic vascular malformations (HVaMs) represent the most frequent type of visceral involvement, demonstrated in approximately 78% of HHT patients, however only 8% being symptomatic [[
The emergence of contrast-enhanced ultrasound (CEUS) has exceptionally improved the ability to image the circulation in some disease circumstances (e.g. in confined liver lesions [[
To be able to sub-classify a high risk cohort of asymptomatic HHT patients with potential therapeutic indication, we improved the technical preconditions by implementation of motion adjustment in VueBox mode, and detection is fitted for every image to equalise for breathing artifacts. Moreover, we now examined a substantially bigger cohort of 34 patients (31 of them presenting HvAMs).
CEUS imaging information of 34 cases were retrospectively studied. Diagnostic analysis was made taking account of the Curaçao criteria. The database was browsed for every patient in the years 2015–2017 who has undergone CEUS screening after being diagnosed with HHT in the Ear-Nose-Throat (ENT) department of the University Hospital of Regensburg (UKR).
This investigation was approved specifically by the ethical committee of the UKR (approval number: 15-104-0233), all patients agreeing by written informed consent to injection of contrast agent for CEUS examination. The ethical committee waived the requirement for informed consent regarding the patient records used in this retrospective study.
Each CEUS examination was performed with a high-end US scanner (LOGIQ E9, GE Healthcare, Milwaukee, USA). The frequency of the convex transducers straddled from 1.0 to 6.0 MHz, each being constructed for abdominal application. Contrast harmonic imaging (CHI) in the form of amplitude modulation (AM) or pulse inversion harmonic imaging (PIHI) was implemented in the US device. A sulfur hexafluoride-filled microbubble contrast agent (SonoVue, Bracco, Milan, Italy) was utilized in this study. A capacity of 1.0 to 2.4 ml of this agent was applied intravenously as a bolus in the antecubital vein, followed by application of 10 ml of 0.9% NaCl.
Each CEUS examination was conducted by one radiologist with more than five years of expert knowledge in CEUS and who evaluated more than 3000 US/year across more than 15 years. Homogenous imaging configurations were utilized and all the US examinations were conducted according to standard procedure. Complete screening of the liver was accomplished by B-Mode examination previous to CEUS for every patient. Then, using CCDS, flow parameters from the portal vein, the hepatic artery (center, right and left part of the liver) and the liver veins were documented. For CEUS a sweep technology was applied for assessment of contrast enhancement in the center and the peripheral parenchymal regions. The mechanical index (MI) was decreased below 0.2, which permits efficient tissue annulment to generate almost pure microbubble pics and impede their corrosion. CEUS operating mode and a chronograph were initiated simultaneously when contrast agent was administered. The CEUS clips until 120 s following application were recorded continously, neither in any change in the machine configurations nor movement of the tansducer. After 120 s the transducer was stired to examine the entire liver. For repeated evaluations Baseline US images and CEUS movie clips were stored digitally on the hard disks of the US device and transferred to an archiving software for evaluation.
All US images and clips were analyzed retrospectively as stored DICOM by two impartial scientists who were not involved in the examination process and were uninformed about pertinent clinical, laboratorial, histopathological data and the results of other imaging techniques. Different opinions on the enhancement pattern and intensity were solved by consent. The results were examined concerning the proposed sonographic criteria by Caselitz [[
The CEUS phase was subdivided into arterial phase (10–45 s from contrast agent administration), portal venous phase (45–120 s) and late phase (121–360 s) [[
The digital stored DICOM cine loops (up to 1 min) were uploaded and opened for blinded and impartial evaluation by an external software in the VueBox (BRACCO, Italy) on a different computer. The development of VueBox diminishes current limitations and facilitates quantification in a standardized manner. VueBox is color-coded, off-line, general-purpose perfusion program for dynamic CEUS investigations that utilizes automatic in-plane movement adjustment [[
The VueBox display is partitioned into four quadrants: the primordial image with the ROIs is posted in the upper left quadrant, the correlatively parametric image is shown in the upper right quadrant, the associated TICs [[
The VueBox can linearize and normalize intensity values acquired with various US devices, transducers and post-processing configurations, utilizing certain calibration files. Whereas the recorded cine clips were imported, the details oft the device and configuration that are utilized are inscribed from a preseted list of adjustments or read self-acting from the file header (ASR function disposable for certain devices). Calibration files for the US device and for the configuration that are utilized are supplied by Bracco [[
The statistical analysis was performed applying Prism 6 software (Graphpad, La Jolla, CA, USA). The continuous values were indicated as mean ± standard error of the mean (SEM). The relation between numerical data was examined utilizing one- way ANOVA. P-values below 0,05 were considered statistically significant. Correlation between data was made by regression analysis. Regression formula and coefficient of determination (R
The patients were 11 men and 23 women, with a mean age of 59.3 years (range, 21–84 years) at the moment of HVaM diagnosis. HVaMs could be proved in 31 out of 34 patients. Malignant lesions were not detectable in any of the cases (Table 1).
Table 1: Basic characteristics of 34 patients with HHT.
case no. gender (M/F) age (years) HVaMs (yes/no) malignant lesions (yes/no) group (1/2) peak enhancement hilus/shunt(%) portal vein diameter (cm) portal vein peak velocity (cm/s) Buscarini grading 1 F 83 Yes No 2 66.0 - 45 3 2 F 60 Yes No 1 27.1 13.8 - 4 3 F 75 Yes No 1 5.2 15.6 20 - 4 F 50 Yes No 1 6.2 - 20 3 5 F 36 Yes No 1 7.8 - - - 6 F 75 Yes No 1 19.8 - - 4 7 F 58 Yes No 2 90.6 10.4 40 - 8 F 65 Yes No 2 69.0 - - - 9 F 66 Yes No 1 9.7 - 23 3 10 F 52 Yes No 2 55.8 - - 2 11 F 76 Yes No 1 11.9 11.5 20 - 12 F 49 Yes No 1 12.4 - 27 - 13 F 55 Yes No 1 30.7 - - 3 14 M 72 Yes No 1 11.1 - 25 3 15 F 21 Yes No 2 56.9 9.5 - 1 16 M 69 Yes No 1 1.2 - 25 3 17 F 62 Yes No 1 8.1 - - 3 18 F 46 Yes No 2 49.0 10.2 30 - 19 F 38 No No - - - - - 20 M 76 Yes No 1 17.6 - - - 21 M 57 No No - - - - - 22 F 69 Yes No 2 132.5 - - - 23 M 66 Yes No 2 45.0 - 40 - 24 M 51 No No - - - - - 25 F 45 Yes No 1 29.1 - - 3 26 M 75 Yes No 1 24.1 - - 3 27 F 31 Yes No 1 6.4 - - - 28 F 48 Yes No 2 75.6 - - - 29 F 84 Yes No 2 50.0 - - - 30 M 62 Yes No 2 51.3 - - - 31 F 57 Yes No 1 9.7 - - - 32 F 42 Yes No 1 20.6 - - 3 33 M 73 Yes No 1 25.8 - - - 34 M 72 Yes No 2 76.7 - 30 2
Marked significant differences (p < .0001) in all perfusion parameter values were identified between the three regions, to the effect that uppermost values were found in the shunt region (100%), next in the hilar region (PE 32.6%; WiAUC 33.9%; WiPI 34.1%), and the lowest in the hepatic parenchyma (PE 10.2%; WiAUC 12.0%; WiPI 9.5%). The relative differences between the regions were alike for PE, WIAUC and WiPI (Fig 2).
In our study, the perfusion parameter values varied among the patients but it was obviously that the relative difference between PE, WIAUC and WiPI values in the shunt region compared to hilus and hepatic parenchyma was dramatically and significantly increased in one group of patients (group 1: hilus PE 12.1%; WiAUC 15.1%; WiPI 17.2%; liver parenchyma PE 7.2%; WiAUC 8.7%; WiPI 7.4%) vs. the other (group 2: hilus PE 69.8%; WiAUC 73.5%; WiPI 69.6%; liver parenchyma PE 15.5%; WiAUC 18.9%; WiPI 14.9%). We choose 40% as cut-off value and the shunt region/hilus region ratio as decisive for distribution of patient data to group 1 respectively 2, this means that all patients with perfusion parameters lower than 40% in hilus region compared to shunt region were repartitioned to group 1, the other to group 2. Beyond the differences to the shunt region, in group 1 the hilus region and the hepatic parenchyma showed similar perfusion patterns, while in group 2 the hilar perfusion values were evidently higher compared to the liver parenchyma. Moreover, PE, WIAUC and WiPI in the hepatic parenchyma was decreased in group 1 compared to group 2 (Fig 3).
Aditionally, we screened the patient files for clinical data to provide evidence for correlation to the parameter results. As shown in Fig 4, in group 1 the intrahepatic portal vein diameter was significantly higher (p<0.05), while portal vein peak velocity was significantly lower (p<0.001) than in group 2. Moreover, Buscraini grading was significantly elevated (p<0.01) in group 1 compared to group 2. By performing regression analysis (Fig 5), we could provide evidence for the association between these data and PE or WiPI, to the effect that the best correlation could be evidenced to portal vein peak velocity (PE: R
HHT is an uncommon autosomal dominantly transmitted disorder characterized by systemic vascular dilatation leading to arteriovenous fusion in the form of telangiectases or major vascular malformations, implying the chance of hemorrhagic incidents [[
HVaMs can be diagnosed in the majority of HHT cases, however rarely (8%) being symptomatic [[
In our latest study we evaluated for the first time HVaMs in a cohort of patients (n = 18) using CEUS and adding quantitative perfusion analysis. Our results revealed significant differences in TTP and AUC values in four selected regions: hepatic artery, shunt region, portal vein and hepatic parenchyma.
This time, we ameliorated the preconditions by implementation of the VueBox mode and by evaluation of a considerably bigger cohort of 34 patients. HVaMs could be ascertained in 91% of the patients, thus in higher percentage than in literature (78%) [[
Performed by an expert, CEUS is a reasonable examination to investigate the dynamic microcirculation in liver disorders [[
Our analyses revealed significant highest PE, WiAUC and WiPI in the shunt region, subsequently in the hilar region, and the lowest in the liver parenchyma. Interestingly, the relative differences between the regions were uniform for PE, WIAUC and WiPI, so that measuring of one parameter could be enough for diagnosis and follow-up of HHT.
One marker parameter could be PE which was implyed also by our group in the evaluation of successful treatment after percutaneous interventional procedures for liver tumors [[
The group with markedly enhanced perfusion intensity could be the high risk cohort of HHT patients with the highest benefit regarding angiogenesis inhibitors like bevacizumab for HVaM treatment. To strengthen this presumption, we examined the available patient files for clinical information to provide evidence for linkage to the parameter findings. Portal hypertension is one of the most common complications of HHT. It is associated with higher portal vein diameter [[
By regression analysis, we could provide evidence for the association between these data and PE or WiPI, while surprisingly WiAUC values could not be correlated to the above mentioned clinical parameters. Therefore, we conclude that not every TIC parameter which is significantly increased in the shunt region, compared to other regions of the liver, has obligatory clinical significance.
Of course, these presumptions have to be tested in prospective trials correlating CEUS findings with clinical parameters (liver parameters, high-output cardiac failure, portal hypertension, iron deficiency anemia). This will be also necessary for better selection of the perfusion parameter cut-off values when repartitioning them to the two groups. We arbitrary have chosen 40% hilus/shunt region as cut-off value in this study to show the existence of at least two distinct groups with different perfusion patterns.
Thus far, there are no contraindications for recurrent injections of SonoVue. Nevertheless, allergic responses towards this contrast agent can emerge [[
A limitation is that VueBox is not incorporated in the US device. This sophisticated investigation needs both an exercised investigator and extra-equipage. The examination with VueBox is time consuming requiring nearly 30 minutes per examination.
A previous critical point, that a lot of ultrasound investigations cannot be evaluated because of movement and breathing artifacts, is eliminated by VueBox thanks to the incorporated motion compensation [[
As another limitation of this study, information about clinical parameters was missing in many cases because the patients are mainly treated in hospitals far away from the University Hospital of Regensburg and are coming only for specialized evaluation in our ENT department and for CEUS examination in our US Center.
The expertise about US properties of HVaMs augmented in the last years, particularly by applying CCDS- and PD-US but there is few knowledge about quantitative perfusion characteristics. Our study showed significant differences in PE, WiAUC and WiPI values in the three determined areas: shunt region, hilus and hepatic parenchyma. Besides, the relative perfusion parameter values in the shunt region compared to other areas were significantly elevated in one subset of patients. As to that, we could correlate PE and WiPI to clinical parameters (portal vein diameter, portal vein peak velocity, Buscarini grading). These novel results could be utilized to sub-classify a high risk cohort of asymptomatic patients with therapeutic indication. Moreover, with novel upcoming therapeutic modalities like angiogenesis inhibitor bevacizumab, treatment of HVaMs and their complications will get more appealing in future. Thus, CEUS investigation is able to fill the hole of necessary precise cost-effective screening methods in HHT patients with HVaMs.
S1 Table. The values (extracted from images) behind the means, standard deviations and other measures reported used to build graphs. (XLSX)
DIAGRAM: Fig 1: Arteriovenous hepatic malformations (shunts) in one exemplary case with HHT. CEUS image and TIC-analysis illustrating peak enhancement. Intrahepatic tortuos vascularization in segment IV and VIII of the liver being appreciable by early hyperenhancement in the course of the arterial phase following injection of 2.0 ml contrast agent. For TIC analysis three regions of interest (ROIs) were positioned in the shunt region (yellow), hilus region (purple) and hepatic parenchyma (white). TIC analysis demonstrated significant highest PE in the shunt region, next in the hilus and lowest in the hepatic parenchyma. The VueBox screen is segmented in four quadrants: the original image with the ROIs is showed in the upper left quadrant, the corresponding parametric image is depicted in the upper right quadrant, the corresponding TICs are displayed in the lower left quadrant in the color corresponding to the ROI in the image above and the numeric values of the chosen curve parameter is shown in the lower right quadrant.
DIAGRAM: Fig 2: Quantitative perfusion data (TIC) analyzed by CEUS combinend with VueBox color-coded perfusion software within shunt region, hilus region and hepatic parenchyma in 31 patients with diagnosed HHT. Percentage in relation to PE (A), WiAUC (B) and WiPI (C) of the shunt region (100%). Marked significant distinctions (p<0.0001) in PE, WiAUC and WiPI values was identified between the three regions, to the effect that uppermost values were detected in the shunt region (100%), next up in the hilus (PE 32.6%; WiAUC 33.9%; WiPI 34.1%) and the lowest were demonstrated in the liver parenchyma (PE 10.2%; WiAUC 12.0%; WiPI 9.5%).
DIAGRAM: Fig 3: Subset analysis of quantitative perfusion data (TIC) evaluated by CEUS combinend with VueBox color-coded perfusion software within shunt region, hilus region and hepatic parenchyma in 31 patients with diagnosed HHT. Percentage in relation to PE (A), WiAUC (B) and WiPI (C) of the shunt region (100%). Marked significant distinctions (p<0.0001) in PE, WiAUC and WiPI values was identified between the two groups concerning the three selected regions, to the effect that in group 1 (hilus PE 12.1%; WiAUC 15.1%; WiPI 17.2%; liver parenchyma PE 7.2%; WiAUC 8.7%; WiPI 7.4%) obvious lower perfusion parameters could be demonstrated when compared to group 2 (hilus PE 69.8%; WiAUC 73.5%; WiPI 69.6%; liver parenchyma PE 15.5%; WiAUC 18.9%; WiPI 14.9%).
DIAGRAM: Fig 4: Clinical parameters in group 1 vs. group 2 of our patient cohort. Intrahepatic portal vein diameter in cm (A), portal vein peak velocity in cm/s (B) and Buscarini grading (C) in group 1 compared to group 2 of our patient cohort. Significant distinctions (A: p<0.05; B: p<0.001; C: p<0.01) was identified between the two groups, to the effect that in group 1 the intrahepatic portal vein diameter was significantly higher (13.6 cm vs. 10.0 cm; n = 3), while portal vein peak velocity was significantly lower (22.8 cm/s vs. 37.0 cm/s; n = 5–7) than in group 2. Moreover, Buscraini grading was significantly elevated in group 1 compared to group 2 (3.2 vs. 2.0; n = 4–11).
DIAGRAM: Fig 5: Correlation between clinical parameters and TIC parameters of our study cohort. Regression analysis showing the relationship between portal vein diameter (in cm), portal vein peak velocity (in cm/s), Buscarini grading and PE (A-C), WiAUC (D-F), WiPI(G-I) (each: hilus/shunt in %). Regression formula and coefficient of determination (R2) is indicated for each diagram.
By Roland C. Schelker, Writing – review & editing; Kornelia Andorfer, Writing – review & editing; Franz Putz, Writing – review & editing; Wolfgang Herr, Writing – review & editing and Ernst-Michael Jung, Writing – review & editing