A Cross-Sectional MRI T2* Study of Pancreatic and Pituitary Hemosiderosis in 180 Thalassemia Major Patients in Hong Kong.

Background: The use of magnetic resonance imaging (MRI) for organ specific iron assessment has allowed better tailoring of chelation therapy. Since endocrine failure is common in thalassemia major (TM) patients, we explored the utility of rapid T2* MRI assessment of hemosiderosis in the pancreas and pituitary. The results were correlated with standard T2* heart and liver MRI assessments and clinical data.

Material and methods: A total of 180 TM patients (M:F = 91:89, median age, range 12–48) were scanned on a 1.5 T scanner. (Sonata, Siemens Medical, Erlanger, Germany). T2* myocardium was assessed by a cardiac gated single breath hold 8-echo sequence (CMRtools; London, UK). The T2* liver, pancreas and pituitary were performed by a breath hold 20-echo sequence. Subcutaneous deferoxamine was used for chelation, except for addition of deferiprone in 24 cases for 1 year.

Results: There was a high incidence of hemosiderosis of heart (severe T2*<12ms: 34%, mild-moderate <20ms, 15%) and liver (severe T2*<1.4ms, 14% mild-moderate <6.3ms, 63%). Iron overload above normal control was commonly found in the pancreas (T2*<23ms, 84%) and pituitary (T2*<5.9ms, 24%). Pancreatic T2* correlated with pituitary T2* (p=0.007, r=0.2), cardiac T2*(p<0.001, r=0.33), liver T2* (p<0.001, r=0.35), ferritin (p=0.004, r=−0.19) and age (p=0.033, r=0.16). Similarly pituitary T2* related to cardiac T2* (p<0.001, r=0.36) and liver T2* (p=0.026, r=0.17). On multivariate analysis, however, pancreatic T2* related to both heart T2* (p<0.001) and liver T2* (p=0.001), while pituitary T2* only related to heart T2* (p<0.001). Documented complications amongst the cases included heart failure (ejection fraction EF<55%, n=28, 16%), hypogonadism (n=84,47%), diabetes mellitus (n=44, 25%), hypoparathyroidism (n=16, 9%) and hypothyroidism (n=36, 20%), with hepatitis B and C carrier state in 2% and 25% respectively. On univariate and multivariate analysis, all 4 endocrine failures correlated with only cardiac T2* results (all p<0.001) and age (all p<0.001), but not with pituitary or pancreatic T2* results. The EF correlated with T2* of pituitary, pancreas and heart, but only MRI heart T2* correlation remained significant on multivariate analysis.

Conclusions: MRI pituitary and pancreatic evaluation is viable in a cohort of poorly chelated Chinese thalassemia major patients on subcutaneous deferoxamine treatment. However, an abnormal cardiac T2* result is a good surrogate for endocrine iron overload and appeared more relevant in predicting endocrine complications.