Imaging of Body Iron Stores in Transfusion-Dependent Patients By Liver Dual- Energy CT

[Background] Chronic red blood cell transfusions, leading to iron overload, cause hepatic, cardiac, and endocrine dysfunction. It is very important to monitor body iron stores and to start optimal iron chelation therapy. Serum ferritin, which is widely used as a surrogate marker of body iron stores, elevate under inflammation or liver injury. Therefore, reliable techniques to evaluate body iron stores are needed. The liver iron concentration (LIC) is thought to be an indicator of total body iron stores and measurement of the T2* value by MRI has been a standard noninvasive technique to evaluate LIC. It should be worthwhile using CT, which is lower cost and widely applied in clinical setting. Dual-energy CT (DECT) is a technique to obtain additional information regarding tissue composition compared with what single-energy CT can provide. This technique is based on the fact that substances show different densities by two different energies. However, the role of DECT in monitoring LIC remains to be clarified. We examined whether a DECT could be a new technique for the measurement of LIC.

[Patients and Methods] Eight transfusion-dependent patients underwent DECT. Patient 1 was a 54-year-old male with MDS (RCMD-RS). He received 66 U red blood cell transfusions in our hospital, and depended on transfusion in another hospital, but the total doses were not available. Patient 2 was a 37-year-old male with AML in 2^nd relapse. His total red blood cell transfusions were 54 U. Patient 3 was a 66-year-old female with AML with MRC in 1^st CR. She received 37 U red blood cell transfusions in our hospital, and depended on transfusion in another hospital, but total doses were not available. Patient 4 was a 47-year-old female who had received renal transplantation for chronic renal failure. She received 12 U red blood cell transfusions in our hospital, and had a long history of transfusion dependence in another hospital, but total doses were not available. Patient 5 was a 57-year-old male with MDS (RCMD). His total red blood cell transfusions were 148 U, and he received iron chelation therapy. Patient 6 was a 65-year-old male with AML with MRC. His total red blood cell transfusions were 82 U, and he received iron chelation therapy. Patient 7 was a 47-year-old male with AML in 3^rd CR. He received 28 U red blood cell transfusions in our hospital, and depended on transfusion in another hospital, but total doses were not available. Patient 8 was a 52-year-old female with AA. Her total blood cell transfusions were 92 U.

[Results] All patients were examined for serum ferritin and patients 1, 3, 4, 6, 7, and 8 also underwent liver MRI. Serum ferritin levels of patients 1, 3, 4, 6, 7, and 8 were 961, 2168, 7875, 795, 1921, and 5104 ng/ml, respectively. These patients showed hypointensity on MRI T2*-weighted images, and also showed liver iron deposition by DECT. Serum ferritin of patient 5 was 4042 ng/ml, and he showed liver iron deposition by DECT. Serum ferritin of patient 2 was 6113 ng/ml, and he did not show liver iron deposition by DECT.

[Conclusion] Our results suggest that liver DECT could visualize liver iron deposition of transfusion-dependent patients and could be a new technique for the measurement of LIC instead of MRI.