SUMMARY

OBJECTIVE:

The aim of this study was to investigate the correlation of fibrosis stages in cases of chronic hepatitis by comparing shear wave elastography and diffusion-weighted magnetic resonance imaging.

METHODS:

A total of 46 chronic hepatitis patients with an age range of 20-50 years were classified into three groups based on their fibrosis stages. Comparison group 1: the presence of fibrosis (S0 and S1≤); comparison group 2: the presence of significant fibrosis (≤S2 and S3≤); and comparison group 3: the presence of cirrhosis (≤S4 and S6). Shear wave velocities were measured by acoustic radiation force impulse elastography. Diffusion-weighted magnetic resonance imaging was performed on a 3.0 Tesla MRI device.

RESULTS:

In comparison group 1 (S0 and S1≤), the area under the curve, sensitivity, and specificity of acoustic radiation force impulse values were 0.784, 87, and 60%, respectively, while these values were 0.718, 80, and 66%, respectively, for apparent diffusion coefficient . In comparison group 2 (≤S2 and S3≤), the area under the curve, sensitivity, and specificity of acoustic radiation force impulse values were 0.917, 80, and 86%, respectively, and the apparent diffusion coefficient values were 0.778, 90, and 66%, respectively. In comparison group 3, the area under the curve, sensitivity, and specificity of acoustic radiation force impulse values were 0.977, 100, and 95%, respectively. There was no statistically significant difference between the apparent diffusion coefficient values of the cases in the three groups (p=0.132).

CONCLUSION:

Noninvasive methods are gaining importance day by day for staging hepatic fibrosis. Acoustic radiation force impulse elastography was evaluated as a more reliable examination than diffusion-weighted magnetic resonance imaging in revealing the presence of fibrosis, determining significant fibrosis, and diagnosing cirrhosis.

KEYWORDS:
Hepatitis; Elastography; ARFI imaging; Diffusion weighted MRI

INTRODUCTION

Hepatic fibrosis occurs as a result of chronic liver diseases. In response to liver injury, hepatic lobules collapse, fibrous septa form, and hepatocyte regeneration nodules form. Fibrosis, for which acute pathologies are reversible, progresses to portal hypertension and cirrhosis. Factors that cause liver fibrosis are viral hepatitis (B, C, and D), metabolic causes (hemochromatosis, alpha-1 antitrypsin deficiency, Wilson disease, galactosemia, tyrosinemia, and type IV glycogen storage disease), hepatic venous obstruction, toxins and drugs (alcohol, amiodarone, methotrexate, etc.), primary biliary cirrhosis, autoimmune hepatitis, helminths (schistosomiasis), cryptogenic cirrhosis, and nonalcoholic steatohepatitis, which is a risk factor for the development of hepatocellular carcinoma¹1. Guyot C, Lepreux S, Combe C, Doudnikoff E, Sage PB, Balabaud C, et al. Hepatic fibrosis and cirrhosis: the (myo)fibroblastic cell subpopulations involved. Int J Biochem Cell Biol. 2006;38(2):135-51. https://doi.org/10.1016/j.biocel.2005.08.021
https://doi.org/https://doi.org/10.1016/... ^,22. Friedman SL. Molecular regulation of hepatic fibrosis, an integrated cellular response to tissue injury. J Biol Chem. 2000;275(4):2247-50. https://doi.org/10.1074/jbc.275.4.2247
https://doi.org/https://doi.org/10.1074/... ^,33. Ascha MS, Hanouneh IA, Lopez R, Tamimi TA, Feldstein AF, Zein NN. The incidence and risk factors of hepatocellular carcinoma in patients with nonalcoholic steatohepatitis. Hepatology. 2010;51(6):1972-8. https://doi.org/10.1002/hep.23527
https://doi.org/https://doi.org/10.1002/... ^,44. Toman D, Sengul I, Pelikán A, Sengul D, Vavra P, Ihnat P, et al. A narrative review on nonalcoholic fatty liver disease and nonalcoholic steatohepatitis versus hepatocellular carcinoma: do you mind? Rev Assoc Med Bras. 2022;68(6):871-4. https://doi.org/10.1590/1806-9282.20220268
https://doi.org/https://doi.org/10.1590/... . The incidence of hepatocellular carcinoma increases in patients who develop fibrosis and cirrhosis⁵5. Parkin DM, Bray F, Ferlay J, Pisani P. Global cancer statistics, 2002. CA Cancer J Clin. 2005;55(2):74-108. https://doi.org/10.3322/canjclin.55.2.74
https://doi.org/https://doi.org/10.3322/... ^,66. Toman D, Sengul I, Pelikán A, Sengul D, Vavra P, Ihnát P, et al. Hepatocellular carcinoma versus nonalcoholic fatty liver disease: metabolic, environmental, and genetic association? De facto? Rev Assoc Med Bras. 2022;68(5):708-11. https://doi.org/10.1590/1806-9282.20220147
https://doi.org/https://doi.org/10.1590/... . Additionally, recent studies have reported that nonalcoholic fatty liver disease may be a potential risk factor for the development of hepatocellular carcinoma⁶6. Toman D, Sengul I, Pelikán A, Sengul D, Vavra P, Ihnát P, et al. Hepatocellular carcinoma versus nonalcoholic fatty liver disease: metabolic, environmental, and genetic association? De facto? Rev Assoc Med Bras. 2022;68(5):708-11. https://doi.org/10.1590/1806-9282.20220147
https://doi.org/https://doi.org/10.1590/... ^,77. Dongiovanni P, Romeo S, Valenti L. Hepatocellular carcinoma in nonalcoholic fatty liver: role of environmental and genetic factors. World J Gastroenterol. 2014;20(36):12945-55. https://doi.org/10.3748/wjg.v20.i36.12945
https://doi.org/https://doi.org/10.3748/... . Noninvasive fibrosis grading imaging techniques have recently gained much attention, as advanced diagnostic tools are important in slowing the fibrosis development process and therefore in mitigating the incidence of hepatocellular carcinoma.

Ultrasound (US) is generally the preferred imaging method for radiological evaluation of the liver. US elastography plays an important role in the characterization of diffuse liver diseases and focal liver lesions⁸8. Sporea I, Raţiu I, Sirli R, Popescu A, Bota S. Value of transient elastography for the prediction of variceal bleeding. World J Gastroenterol. 2011;17(17):2206-10. https://doi.org/10.3748/wjg.v17.i17.2206
https://doi.org/https://doi.org/10.3748/... .

Acoustic radiation force impulse (ARFI) is an up-to-date method that has been widely used in recent years. It provides information for tissue characterization according to the response of tissues to applied force. The fact that US elastography can be used to image tissues was first demonstrated in 1987⁹9. Krouskop TA, Dougherty DR, Vinson FS. A pulsed Doppler ultrasonic system for making noninvasive measurements of the mechanical properties of soft tissue. J Rehabil Res Dev. 1987;24(2):1-8. PMID: 3295197^,1010. Onur MR, Poyraz AK, Ucak EE, Bozgeyik Z, Özercan IH, Ogur E. Semiquantitative strain elastography of liver masses. J Ultrasound Med. 2012;31(7):1061-7. https://doi.org/10.7863/jum.2012.31.7.1061
https://doi.org/https://doi.org/10.7863/... .

Diffusion-weighted magnetic resonance imaging (DW-MRI) can provide additional information about many pathologies in addition to conventional MRI sequences.

Determining the stage of fibrosis development in chronic hepatitis patients is of great importance in terms of preventing the progression to cirrhosis with appropriate treatment methods and determining the response to the treatment applied. Today, percutaneous liver biopsy remains the gold standard diagnostic test for staging fibrosis. Therefore, this study aimed to investigate the correlation between fibrosis stages in cases of chronic hepatitis by comparing shear wave elastography and DW-MRI.

METHODS

Patient selection

Between September 2014 and May 2015, 46 patients (40 males and 6 females) who were followed up with after receiving a diagnosis of histopathologically proven viral hepatitis (HBV and HCV), steatohepatitis, or autoimmune hepatitis across the various clinics of Health Sciences University, Gulhane School of Medicine, were evaluated prospectively. US examinations, measurement of ARFI values, and DW-MRI examinations were conducted for all patients at least 1 week before biopsy. The patients were classified into three groups as follows: comparison group 1, presence of fibrosis (S0 and S1≤); comparison group 2, presence of significant fibrosis (≤S2 and S3≤); and comparison group 3, presence of cirrhosis (≤S4 and S6).

Approval for this study was obtained from the Institutional Ethical Review Board (dated May 30, 2014, decision no. 8000-259-14/1560), and the study followed the tenets of the Declaration of Helsinki.

Acoustic radiation force impulse elastography analysis

B-mode US and ARFI elastography measurements were evaluated on a Siemens Acuson S3000 device (Siemens Medical Solutions, Mountain View, CA, USA) using a 6C1 HD convex probe with Virtual Touch Quantification (VTQ) software.

The values were obtained in m/s units using a 10×5 mm region of interest (ROI) placed at least 2 cm away from the Glisson capsule. The median values of 10 shear wave velocities measured were used (Figure 1A).

Magnetic resonance imaging protocol

A Sense-XL Torso coil in a 3.0 Tesla (T) superconductive MR (Philips 3T Achieva Release 3.2.3.0) was used. DW images were obtained using the following parameters: eco-planar spin echo, the fat suppression technique, and breath hold: 1241/52 repetition time (TR)/echo time (TE); 90° flip angle; 375×302×255 mm field of view (FOV); 124×100 matrix; and 7 mm thickness. The acquisition time for the images was 3 min and 12 s. Diffusion gradient b values of 0, 100, and 800 were used in DW-MRI. These values were applied to minimize diffusion anisotropy in three orthogonal directions (x, y, and z).

The images obtained were transferred to a separate workstation (DynaCAD Version 2.1.6), and measurements from apparent diffusion coefficient (ADC) maps were made at this station (Figure 1B).

Magnetic resonance imaging analysis

ADC values were measured using circular ROIs of approximately 1 cm² from the right liver lobe. ADC values were measured in mm²/s from the right liver lobe parenchyma. ROIs at least 1 cm away from the Glisson capsule, where there were no main vascular structures, focal lesions, or artifacts, were placed on ADC maps simultaneously.

Evaluation of liver biopsy

The Ishak scoring system¹¹11. Ishak K, Baptista A, Bianchi L, Callea F, Groote J, Gudat F, et al. Histological grading and staging of chronic hepatitis. J Hepatol. 1995;22(6):696-9. https://doi.org/10.1016/0168-8278(95)80226-6
https://doi.org/https://doi.org/10.1016/... was used to stage fibrosis. Accordingly, stage (S)0 was evaluated as no fibrosis, S1-S2 as mild fibrosis, S3-S4 as moderate fibrosis, and S5-S6 as advanced-stage fibrosis¹¹11. Ishak K, Baptista A, Bianchi L, Callea F, Groote J, Gudat F, et al. Histological grading and staging of chronic hepatitis. J Hepatol. 1995;22(6):696-9. https://doi.org/10.1016/0168-8278(95)80226-6
https://doi.org/https://doi.org/10.1016/... .

Statistical analysis

SPSS for Windows version 15.00 (SPSS Inc., Chicago, IL, USA) was used. The t-test and the Fisher-corrected chi-squared test were used to determine intergroup differences. For each group, the area under the curve (AUC), according to the ARFI and ADC values, was measured at a 95% confidence interval (CI). p-Values less than 0.05 were considered statistically significant.

RESULTS

The mean age of the 46 patients was 34.52±9.6 years, and the mean body mass index (BMI) was 25.226±3.27. The disease distribution and fibrosis stages are shown in Table 1.

The comparison of patients in group 1 was performed to detect the presence of fibrosis between patients with S0 fibrosis and patients with fibrosis at any stage (S1≤). ARFI elastography was determined to be more effective than DW-MRI in detecting any stage of fibrosis. When the optimal cutoff value for ARFI elastography was determined to be 1.25 m/s in separating the two groups, the sensitivity was 87%, and the specificity was 60%. When the optimal cutoff value for DW-MRI was determined to be 1.110×10^-3 mm²/s, the sensitivity was 80%, and the specificity was 66%.

Comparison group 2 featured patients with S0-S2 (≤S2) fibrosis and was compared to patients with S3-S6 (S3≤) fibrosis to reveal the presence of significant fibrosis. ARFI elastography was determined to be more effective than DW-MRI in diagnosing significant fibrosis. When the optimal cutoff value for ARFI elastography was determined to be 1.52 m/s in separating the two groups, the sensitivity was 80%, and the specificity was 86%. When the optimal cutoff ADC value for DW-MRI was determined to be 1.063×10^-3 mm²/s, the sensitivity was 90%, and the specificity was 66%.

Comparison group 3 was created to compare patients with S0-S4 (S4≥) fibrosis and patients with S5 and S6 fibrosis (precirrhosis+cirrhosis) to distinguish cirrhosis cases. ARFI elastography was determined to be more effective than DW-MRI in diagnosing cirrhosis. In separating the two groups, when the optimal cutoff value for ARFI elastography was determined to be 1.8 m/s, the sensitivity was 100%, and the specificity was 95%.

The AUC, optimal cutoff value, sensitivity, specificity, positive predictive value, negative predictive value, and positive-negative likelihood ratio of all three groups are summarized in Table 2.

DISCUSSION

Image parameters, such as magnetic sensitivity, spatial resolution, signal-to-noise ratio, and pathophysiological factors (e.g., cellular density and tissue components), affect ADC¹²12. Woodhams R, Matsunaga K, Iwabuchi K, Kan S, Hata H, Kuranami M, et al. Diffusion-weighted imaging of malignant breast tumors: the usefulness of apparent diffusion coefficient (ADC) value and ADC map for the detection of malignant breast tumors and evaluation of cancer extension. J Comput Assist Tomogr. 2005;29(5):644-9. https://doi.org/10.1097/01.rct.0000171913.74086.1b
https://doi.org/https://doi.org/10.1097/... . In comparing the 3.0T MRI device to a 1.5T device, a high magnetic field was shown to increase the signal-to-noise ratio and spatial resolution while decreasing imaging time¹³13. Matsuoka A, Minato M, Harada M, Kubo H, Bandou Y, Tangoku A, et al. Comparison of 3.0-and 1.5-tesla diffusion-weighted imaging in the visibility of breast cancer. Radiat Med. 2008;26(1):15-20. https://doi.org/10.1007/s11604-007-0187-6
https://doi.org/https://doi.org/10.1007/... . In our study, we aimed to benefit from these advantages by using the 3.0T MRI device.

In comparison group 1, the AUC value of the ARFI was 0.784, the sensitivity was 87%, and the specificity was 60%. Lupsor et al.¹⁴14. Lupsor M, Badea R, Stefanescu H, Sparchez Z, Branda H, Serban A, et al. Performance of a new elastographic method (ARFI technology) compared to unidimensional transient elastography in the noninvasive assessment of chronic hepatitis C. Preliminary results. J Gastrointestin Liver Dis. 2009;18(3):303-10. PMID: 19795024 reported AUC, cutoff, sensitivity, and specificity values of 0.709, 1.19 m/s, 62.07, and 85.7%, respectively, in 112 chronic hepatitis C cases with F0 and F1≤ fibrosis. The AUC values between Lupsor et al.’s¹⁴14. Lupsor M, Badea R, Stefanescu H, Sparchez Z, Branda H, Serban A, et al. Performance of a new elastographic method (ARFI technology) compared to unidimensional transient elastography in the noninvasive assessment of chronic hepatitis C. Preliminary results. J Gastrointestin Liver Dis. 2009;18(3):303-10. PMID: 19795024 study and the present study were similar. However, Lupsor et al.¹⁴14. Lupsor M, Badea R, Stefanescu H, Sparchez Z, Branda H, Serban A, et al. Performance of a new elastographic method (ARFI technology) compared to unidimensional transient elastography in the noninvasive assessment of chronic hepatitis C. Preliminary results. J Gastrointestin Liver Dis. 2009;18(3):303-10. PMID: 19795024 reported lower sensitivity and higher specificity values.

In comparison group 1, the AUC of the mean ADC, cutoff, sensitivity, and specificity values were 0.718, 1.110×10^-3 m²/s, 80, and 66%, respectively. Similar to the AUC and sensitivity values in this study, the study by Bonekamp et al.¹⁵15. Bonekamp S, Torbenson MS, Kamel IR. Diffusion-weighted magnetic resonance imaging for the staging of liver fibrosis. J Clin Gastroenterol. 2011;45(10):885-92. https://doi.org/10.1097/MCG.0b013e318223bd2c
https://doi.org/https://doi.org/10.1097/... accepted B values of 0-750 s/m² with a 1.5T system; the AUC, cutoff, sensitivity, and specificity values were 0.79, 1.51×10^-3 m²/s, 75.8, and 78.2%, respectively. The specificity in Bonekamp et al.’s study was found to be higher than in the present study. The different results in our study may be due to differences in the B values, acquisition parameters, susceptibility effects, and magnetic field strengths of the devices.

In comparison group 2, the AUC value of ARFI elastography was 0.917, and that of DW-MRI was 0.778. The sensitivity and specificity values were 80-86% for ARFI elastography and 90-66% for DW-MRI. Friedrich-Rust et al.¹⁶16. Friedrich-Rust M, Nierhoff J, Lupsor M, Sporea I, Fierbinteanu-Braticevici C, Strobel D, et al. Performance of acoustic radiation force impulse imaging for the staging of liver fibrosis: a pooled meta-analysis. J Viral Hepat. 2012;19(2):e212-9. https://doi.org/10.1111/j.1365-2893.2011.01537.x
https://doi.org/https://doi.org/10.1111/... reported that the AUC, cutoff, sensitivity, and specificity values were 0.87, 1.34 m/s, 79, and 85%, respectively. In the present study, similar sensitivity and specificity values were found.

A US liver elastography consensus statement¹⁷17. Barr RG, Wilson SR, Rubens D, Garcia-Tsao G, Ferraioli G. Update to the society of radiologists in ultrasound liver elastography consensus statement. Radiology. 2020;296(2):263-74. https://doi.org/10.1148/radiol.2020192437
https://doi.org/https://doi.org/10.1148/... claimed that most studies using ARFI report that a liver stiffness value of less than 1.5 m/s could help rule out significant fibrosis. For comparison group 2, we assumed that the cutoff value was 1.52 m/s, which is very similar to the value stated in this consensus¹⁷17. Barr RG, Wilson SR, Rubens D, Garcia-Tsao G, Ferraioli G. Update to the society of radiologists in ultrasound liver elastography consensus statement. Radiology. 2020;296(2):263-74. https://doi.org/10.1148/radiol.2020192437
https://doi.org/https://doi.org/10.1148/... .

Furthermore, in comparison group 2, the AUC of the mean ADC, cutoff, sensitivity, and specificity values were 0.778, 1.063×10^-3 m²/s, 90, and 66%, respectively. Bonekamp et al.¹⁵15. Bonekamp S, Torbenson MS, Kamel IR. Diffusion-weighted magnetic resonance imaging for the staging of liver fibrosis. J Clin Gastroenterol. 2011;45(10):885-92. https://doi.org/10.1097/MCG.0b013e318223bd2c
https://doi.org/https://doi.org/10.1097/... reported that the AUC, cutoff, sensitivity, and specificity values were 0.77, 1.33×10^-3 m²/s, 84.9, and 71.4%, respectively. Similar AUC, sensitivity, and specificity values were found in this study. Sandrasegaran et al.¹⁸18. Sandrasegaran K, Akisik FM, Lin C, Tahir B, Rajan J, Saxena R, et al. Value of diffusion-weighted MRI for assessing liver fibrosis and cirrhosis. AJR Am J Roentgenol. 2009;193(6):1556-60. https://doi.org/10.2214/AJR.09.2436
https://doi.org/https://doi.org/10.2214/... conducted a study using B values of 50-400 s/m² in a 1.5T system and reported that the AUC, cutoff, sensitivity, and specificity values were 0.686, 1.03×10^-3 m²/h, 72.6, and 59.3%, respectively. In our study, it was thought that the high sensitivity and specificity values may be due to the use of the 3.0T MRI.

In comparison group 3, there was no statistically significant difference between the ADC values. There may be several reasons why we found a much better result using ARFI elastography than DW-MRI in determining cirrhosis. One of these reasons is the absence of Ishak S5 patients and the fact that there were only two S6 patients. In the present study, although no statistically significant result was obtained with DW-MRI in this comparison group, in the study by Sandrasegaran et al.¹⁸18. Sandrasegaran K, Akisik FM, Lin C, Tahir B, Rajan J, Saxena R, et al. Value of diffusion-weighted MRI for assessing liver fibrosis and cirrhosis. AJR Am J Roentgenol. 2009;193(6):1556-60. https://doi.org/10.2214/AJR.09.2436
https://doi.org/https://doi.org/10.2214/... , when the cutoff value was 0.98×10^-3, the AUC, sensitivity, and specificity were 0.656, 51.7, and 71.4%, respectively.

ARFI elastography showed very good performance in distinguishing the cirrhosis group from the other fibrosis groups, with an AUC of 0.977. The sensitivity and specificity values were found to be 100 and 95%, respectively. In patients (4%) with Ishak S6, the mean ARFI values were found to be significantly higher (1.89 and 1.85 m/s). In the study by Friedrich-Rust et al.¹⁶16. Friedrich-Rust M, Nierhoff J, Lupsor M, Sporea I, Fierbinteanu-Braticevici C, Strobel D, et al. Performance of acoustic radiation force impulse imaging for the staging of liver fibrosis: a pooled meta-analysis. J Viral Hepat. 2012;19(2):e212-9. https://doi.org/10.1111/j.1365-2893.2011.01537.x
https://doi.org/https://doi.org/10.1111/... , the AUC of 0.93 was the highest compared to the other comparison groups. The cutoff value was 1.80 m/s, and the sensitivity and specificity values were 92-86%. In this study, the highest AUC was obtained for the differentiation of cirrhosis. Fierbinteanu-Braticevici et al.¹⁹19. Fierbinteanu Braticevici C, Sporea I, Panaitescu E, Tribus L. Value of acoustic radiation force impulse imaging elastography for non-invasive evaluation of patients with nonalcoholic fatty liver disease. Ultrasound Med Biol. 2013;39(11):1942-50. https://doi.org/10.1016/j.ultrasmedbio.2013.04.019
https://doi.org/https://doi.org/10.1016/... , Karlas et al.²⁰20. Karlas T, Pfrepper C, Wiegand J, Wittekind C, Neuschulz M, Mössner J, et al. Acoustic radiation force impulse imaging (ARFI) for non-invasive detection of liver fibrosis: examination standards and evaluation of interlobe differences in healthy subjects and chronic liver disease. Scand J Gastroenterol. 2011;46(12):1458-67. https://doi.org/10.3109/00365521.2011.610004
https://doi.org/https://doi.org/10.3109/... , and Nierhoff et al.²¹21. Nierhoff J, Chávez Ortiz AA, Herrmann E, Zeuzem S, Friedrich-Rust M. The efficiency of acoustic radiation force impulse imaging for the staging of liver fibrosis: a meta-analysis. Eur Radiol. 2013;23(11):3040-53. https://doi.org/10.1007/s00330-013-2927-6
https://doi.org/https://doi.org/10.1007/... found a sensitivity value of 100% in the differentiation of cirrhosis cases. In these studies, the values for the cirrhosis patient group compared to the whole patient group were reported to be 27¹⁹19. Fierbinteanu Braticevici C, Sporea I, Panaitescu E, Tribus L. Value of acoustic radiation force impulse imaging elastography for non-invasive evaluation of patients with nonalcoholic fatty liver disease. Ultrasound Med Biol. 2013;39(11):1942-50. https://doi.org/10.1016/j.ultrasmedbio.2013.04.019
https://doi.org/https://doi.org/10.1016/... , 26.5²⁰20. Karlas T, Pfrepper C, Wiegand J, Wittekind C, Neuschulz M, Mössner J, et al. Acoustic radiation force impulse imaging (ARFI) for non-invasive detection of liver fibrosis: examination standards and evaluation of interlobe differences in healthy subjects and chronic liver disease. Scand J Gastroenterol. 2011;46(12):1458-67. https://doi.org/10.3109/00365521.2011.610004
https://doi.org/https://doi.org/10.3109/... , and 6%²¹21. Nierhoff J, Chávez Ortiz AA, Herrmann E, Zeuzem S, Friedrich-Rust M. The efficiency of acoustic radiation force impulse imaging for the staging of liver fibrosis: a meta-analysis. Eur Radiol. 2013;23(11):3040-53. https://doi.org/10.1007/s00330-013-2927-6
https://doi.org/https://doi.org/10.1007/... , respectively.

In the US liver elastography consensus statement¹⁷17. Barr RG, Wilson SR, Rubens D, Garcia-Tsao G, Ferraioli G. Update to the society of radiologists in ultrasound liver elastography consensus statement. Radiology. 2020;296(2):263-74. https://doi.org/10.1148/radiol.2020192437
https://doi.org/https://doi.org/10.1148/... , a cutoff interval of 1.7-2.1 m/s for the ARFI value suggests advanced chronic liver disease, and further testing is required for confirmation. In our study, the cutoff value for this category (1.8 m/s) is compatible with this consensus statement¹⁷17. Barr RG, Wilson SR, Rubens D, Garcia-Tsao G, Ferraioli G. Update to the society of radiologists in ultrasound liver elastography consensus statement. Radiology. 2020;296(2):263-74. https://doi.org/10.1148/radiol.2020192437
https://doi.org/https://doi.org/10.1148/... .

There were inconsistent results regarding which b value is sufficient in DW-MRI images, especially due to the small number of studies performed with 3.0T MRI. Although a low b value is affected by capillary perfusion, the perfusion effect, especially above 300 s/m^², disappears²²22. Bruegel M, Holzapfel K, Gaa J, Woertler K, Waldt S, Kiefer B, et al. Characterization of focal liver lesions by ADC measurements using a respiratory triggered diffusion-weighted single-shot echo-planar MR imaging technique. Eur Radiol. 2008;18(3):477-85. https://doi.org/10.1007/s00330-007-0785-9
https://doi.org/https://doi.org/10.1007/... . Therefore, high b values may be more valuable in determining fibrosis²³23. Koinuma M, Ohashi I, Hanafusa K, Shibuya H. Apparent diffusion coefficient measurements with diffusion-weighted magnetic resonance imaging for evaluation of hepatic fibrosis. J Magn Reson Imaging. 2005;22(1):80-5. https://doi.org/10.1002/jmri.20344
https://doi.org/https://doi.org/10.1002/... .

This study has various limitations. First, a larger patient population could not be reached. In particular, the number of patients with advanced-stage fibrosis constituted 4% of the entire study group. The second limitation was that while the liver was evaluated by ADC and ARFI elastography, steatosis, possible effects of iron load, and histological activity index were not taken into account in the comparison. The third limitation was the difficulty in placing the ROI used in ARFI elastography measurements, the difficulty in placing the ROI used during ADC measurements in the same area, and the inability to place the ROI used in ARFI measurements deeper than 8 cm. Another limitation is that the disease groups were not homogeneous because of the inclusion of both viral and nonviral hepatitis patients.

CONCLUSION

Conducting new studies involving larger populations and patient groups using a 3.0 Tesla MRI device with a high signal-to-noise ratio, spatial resolution, and short imaging time will contribute to the diagnosis and treatment follow-up of especially early-stage patients.

REFERENCES

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