Study on the Equation Between Liver MRI T2* Values and Liver Iron Concentration in Thalassemia Patients

Abstract

Background: The liver iron concentration (LICF) provided by FerriScan is already certified. But there are some restrictive factors. Therefore, we explored the relationship curves of LICF and MRI liver T2 *, and constructed the equations for both. Methods: Liver MRI T2* values of 273 thalassemia patients were measured by CMRtools/Thalassemia Tools (CMRtools) and divided into test and verification groups. The T2* values of the test group and LICF were used to build the equation, through which the T2* values of the validation group were converted to the liver iron concentration（LICe）. The relationship between LICe and LICF was explored. According to the clinical liver iron concentration grading, LICF and LICe were grouped to explore the relationship between the them in the validation group. Results: The equation built by the test group was LICF=37.393T2*^(-1.22)（R2=0.971，P＜0.05）. There was no statistical difference between LICe and LICF in the validation group（P＞0.05）; There was significant consistency（W=0.991, P＜0.05）and significant correlation（rs=0.983，P＜0.05） between them .There was no statistical difference in the clinical grading between LICe and LICF in the validation group （P＞0.05）. There was significant consistency between the clinical grading results（K=0.943，P＜0.05. Conclusion: Through the equation LICF=37.393T2*^(-1.22), after measuring the liver T2* value, the liver iron concentration (LIC) equivalent to LICF can be accurately calculated.

Narrative review of magnetic resonance imaging in quantifying liver iron load

“…As mentioned above, LIC reported by liver biopsy have long been used as the "gold standard" for clinical quantification of liver LIC (1,(3)(4)(5). However, due to different research centers or medical institutions, some factors may lead to discrepancies between LIC reported by liver biopsy, including the materials and methods used in the process of liver biopsy, and the heterogeneity of iron in liver tissue, etc.…”

“…So it is not suitable for repeated longitudinal detection in treatment (1,2). At present, most scholars and medical centers prefer to use non-invasive magnetic resonance imaging (MRI) technology for quantitative evaluation of LIC and monitoring of liver iron chelation efficacy (1,(3)(4)(5). With the continuous development of MRI equipment and imaging sequences, T 2 * technique based on MRI gradient recalled echo (GRE) imaging sequence has been identified as the non-invasive preferred method for quantifying tissue iron content (2,(4)(5)(6).…”

“…At present, most scholars and medical centers prefer to use non-invasive magnetic resonance imaging (MRI) technology for quantitative evaluation of LIC and monitoring of liver iron chelation efficacy (1,(3)(4)(5). With the continuous development of MRI equipment and imaging sequences, T 2 * technique based on MRI gradient recalled echo (GRE) imaging sequence has been identified as the non-invasive preferred method for quantifying tissue iron content (2,(4)(5)(6). Many centers have been using the T 2 * relaxation method, the corresponding calibration formula and different software techniques to measure the relevant relaxation parameters of organs, such as T 2 * and R 2 * (1,000/T 2 *) values, so as to indirectly obtain the estimates of LIC of organs (4,6).…”

“…With the continuous development of MRI equipment and imaging sequences, T 2 * technique based on MRI gradient recalled echo (GRE) imaging sequence has been identified as the non-invasive preferred method for quantifying tissue iron content (2,(4)(5)(6). Many centers have been using the T 2 * relaxation method, the corresponding calibration formula and different software techniques to measure the relevant relaxation parameters of organs, such as T 2 * and R 2 * (1,000/T 2 *) values, so as to indirectly obtain the estimates of LIC of organs (4,6). Currently, accurate quantification of organ iron content remains challenging, especially in patients with severe organ iron overload (1,4,6).…”

“…Many centers have been using the T 2 * relaxation method, the corresponding calibration formula and different software techniques to measure the relevant relaxation parameters of organs, such as T 2 * and R 2 * (1,000/T 2 *) values, so as to indirectly obtain the estimates of LIC of organs (4,6). Currently, accurate quantification of organ iron content remains challenging, especially in patients with severe organ iron overload (1,4,6). Therefore, scholars are still looking for a reliable, noninvasive, accurate and reproducible assessment method of organ iron overload (3).…”