Evaluation of iron accumulation in liver tissue by T2* MR, serum ferritin and ARFI (Acoustic radiation force impulse) elastography parameters in children with beta thalassemia major

Aim: The aim of our study is to compare ARFI elastography with T2 * MR and serum ferritin in the evaluation of the severity of iron accumulation and accumulation in the liver in children with beta thalassemia major and to examine the relationship between them. Material and methods: In our study, 40 patients under the age of 18 who were followed up retrospectively between November 2018 and November 2019 by the pediatric hematology department of our hospital with the diagnosis of beta thalassemia major. All of the patients received transfusion and chelation therapy, also there were no signs of localized of liver or systemic additional disease locally in the clinic and laboratory. ARFI elastography examination was performed as a shear wave velocity measurement from 10 different examination areas selected from liver segment 5-8 using Virtual touch tissue quantification (VTQ) software and the mean ARFI velocity value was taken. MRI examination was done with 3Tesla MR device (Philips Ingenia 3T). The multi TE gradient echo (T2 *) sequence was used for iron deposition. To determine the iron load, measurements were made from 10 different examination areas selected from liver segment 5-8 with the help of ROI and the mean value was taken. Iron accumulation intensity was classified as normal-light-medium-heavy according to T2 * MR values. Serum ferritin values of each patient were reached using the hospital database. For serum ferritin values, the range of 10-58 µg / l was considered within normal limits. Relationships between T2 * MR, ARFI elastogtafi and serum ferritin values were evaluated statistically to evaluate iron accumulation in the liver. Findings: Of the patients included in our study, 14 were female and 26 were male. The mean age was 136.25 (± 38.97) months. There was no significant relationship between iron accumulation in the liver and age and gender (p = 0.638, p = 0,878). A negative moderate correlation was found between T2 * MR values and ARFI elastography and serum ferritin values (p = 0.001, p = 0.003). A positive strong correlation was detected between ARFI elastography and serum ferritin values (p = 0.001). When the patients were divided into groups according to the severity of iron accumulation in the liver, 4 patients (10%) had normal iron accumulation in 11 patients (27.5%) and moderate iron accumulation in 25 patients (62.5%). We did not have any patients with heavy iron accumulation. There was a significant difference between these patient groups in terms of mean ARFI elastography and mean serum ferritin values (p = 0.001, p = 0.007). Since the number of patients with normal iron accumulation was low, the normal and light groups were combined and compared with the middle group, and a statistically significant difference was found between these two groups in terms of ARFI elastography and serum ferritin values (p <0.001, p = 0.03). For ARFI elastography and serum ferritin values, the ROC curve was drawn and the area under the curve (AUC) values were obtained (Confidence interval: 95%). Accordingly, the optimal cut-off value of ARFI elastography in separating these two groups was determined to be 1.29 m / s with 88% sensitivity, 80% specificity to determine the parenchymal damage due to moderate iron accumulation in the liver. The optimal cut-off value of serum ferritin value in these two groups was determined as 1456 µg/l with 80% sensitivity and 73% specificity. Results: Since the risk of developing progressive liver damage is high in patients with moderate and severe hepatic iron accumulation, it is very important to identify these patient groups. Today, T2 * MR method is used to determine iron accumulation and degree of accumulation in the liver. However, considering the cost of T2 * MR method, difficulty of access and waiting times, ARFI elastography method can be used to predict the parenchymal effects of moderate iron accumulation in the liver in cases where there is no additional disease, in patients diagnosed with beta thalassemia major or in other cases that cause chronic blood transfusion and can be a guide in the regulation of chelation therapy. Key Words: T2* MR, ARFI, Beta Thalassemia Major