Role of Magnetic Ressonance Imaging – T2* in Hereditary Hemochromatosis.

Hereditary hemochromatosis (HH) is an autossomic recessive disorder characterized by increased iron absorption. Magnetic resonance imaging – T2* (MRI-T2*) has become a reliable and robust methodology to directly assess the iron burden, with better results in transfusional hemosiderosis compared to indirect methods, such as serum ferritin and transferrin saturation (TS). However, little is known about its role in HH.

Describe the demographic profile of HH type 1 patients as to the type of the HFE mutation and correlate laboratory parameters to MRI-T2*results.

We collected data from patients with a positive HFE gene mutation who performed abdominal and/or cardiac MRI-T2* in our institution from 2004 to 2011. Images retrieved from the digital archive were analyzed by two blinded independent radiologists using the Thalassemia-Tools software (Cardiovascular Imaging Solutions, London, UK). Laboratory data available within 6 months before or after the MRI study were analyzed using the t-Student test, Exact Fisher's test analysis and multivariate analyses.

We analyzed 81 patients, 76 (93%) males and 5 (6.2%) females, with a median age of 48 years (21–80). Liver, pancreatic and splenic MRI-T2*values and LIC calculation were performed in 80 patients, and cardiac T2* assessment in 57 patients. The inter-observer T2* variation coefficient was 5%. Serum ferritin was abnormal in 70 patients (90.9%), while TS was abnormal in 34% of the tests.

In our study sample, the H63D mutation was present in 70 patients (86.4%): 11 (13.6%) were homozygous, 59 (72.8%) heterozygous and 7 (8.6%) double heterozygous for C282Y/H63D. Only three patients (3.7%) were homozygous and 6 (7.4%) were heterozygous only for the C282Y mutation. The S65C mutation was detected in heterozygous state in 2 (2.5%) of cases.

Two out 57 cases had a positive T2* result and were classified as light cardiac overload (T2*:18.98 e 19.14 ms). Both had the H63D mutation (1 homozygous and 1 heterozygous). Thirty seven out of 80 patients (46.3%) had liver overload in abdominal MRI (T2*: 3.8–11.4ms), being 33 (41.3%) light overload and four (5%) moderate overload (T2*:1.8–3.8ms). We found that 77.8% of patients with liver overload were C282Y carriers, of which 57.2% had double mutation and 40.3% had H63D mutation in hetero or homozigosity. Pancreatic overload was found in 20 patients (25.1%), while 30 patients (37.5%) had splenic overload. There was a slight correlation (r: 0.365) between liver T2* and splenic T2* (p=0.001).

The presence of C282Y and H63D mutations was statistically associated with a higher frequency of abnormal liver T2* (p=0.017 and p=0.042, respectively). The H63D mutation was associated with iron accumulation in the liver (p=0,037) and homozygous carriers showed higher levels of liver overload (p=0,038).

In our study, serum ferritin was a better surrogate marker for iron overload than ST. In addition, up to 40.3% of patients with H63D mutation had evidence of hepatic iron overload by MRI. These findings differ from the currente literature. The higher RMI positivity might be due to a higher sensitivity to detect lower levels of organic iron. Despite the lack of a control group and laboratory tests or MRI in all the cases studied, our results suggest that RMI-T2* is a promising methodology to guide the therapeutic management of HH patients. The clinical impact of this finding must be investigated in further studies.

No relevant conflicts of interest to declare.