Proton MR Spectroscopic Features According to Change of Hepatic Parenchymal Iron Content after SPIO Injection

PURPOSE: To determine the effect of iron on proton MR spectra (1H-MRS) by evaluating changes in 1H-MRS of the liver according to changes in hepatic parenchymal iron content. MATERIALS AND METHODS: We evaluated serial changes in 1H-MRS of the liver after intravenous infusion of SPIO in 40 rabbits. These were divided into eight groups of five, and in each group, respectively, 1H-MRS and T2WI MR images were acquired prior to SPIO infusion, just after infusion, and at 15 minutes and 1, 2, 4, 24 and 96 hours after infusion. MR spectra were evaluated with particular attention to the curve pattern observed at specific times after the infusion of SPIO, and the results were correlated with the signal intensity observed on T2W1 images and the histologic giade of ilon content of samples of resected liver parenchyma. RESULTS: As observed on T2WI, the mean signal intensity of rabbit liver in its pre-SPIO infusion state, just after infusion, at 15 minutes, and at 1, 2, 4, 24 and 96 hours after SPIO infusion was 121.3 +/-15.5, 41.5 +/-12.7, 30.3 +/-7.9, 31.3 +/-3.5, 33.6 +/-9.4, 45.5 +/-10.9, 80.3 +/-15.7 and 110.4 +/-22.9, respectively(p<0.05). Mean standard deviation of the ratio of the area of the peak (3.9-4.1 ppm) / lipid peak (1.3 ppm) peak at each of the above times except for the pre-infusion state was 1.10 +/-0.13, 1.86 +/-0.21, 1.80 +/-0.30, 1.76 +/-0.27, 1.74 +/-0.20, 0.07 +/-0.02 and 0.03 +/-0.01, respectively(p<0.05). The hepatic parenchymal iron content increased rapidly from just after SPIO infusion, reaching its maximal level (as revealed by histologic specimens) at 15 minutes, sustaining this for up to 4 hours, and then decreasing gradually over periods of 24 and 96 hours. These results show that serial changes in patterns of MR spectra and the signal intensity seen on T2WI images correlate closely with changes in hepatic parenchymal iron content. CONCLUSION: Elevated hepatic parenchymal iron content leads to increases in the relative intensity of unknown peaks at around 4.0 ppm and decreases in the relative intensity of lipid peaks.

CT Finding of Transfusional Hemosiderosis in Patients with Chronic Renal Failure: Clinical Correlation

PURPOSE: To evaluate whether there is any correlation between the CT features of hemosiderosis and clinical findings in patients with chronic renal failure who have received multiple blood transfusions. MATERIALS AND METHODS: Among chronic renal failure patients who had undergone long-term dialysis and received multiple blood transfusions, CT findings in 16 cases in which increased liver attenuation was seen on images obtained for other purpose, were analyzed by three radiologic specialists. The attenuation values of liver, spleen and pancreas compared with that of back muscle were correlated with the amount and duration of transfusion, and blood ferritin level. RESULTS: In 15 of these 16 case, blood ferritin level was examined; 14 showed more than 300ng/ml. Increased attenuation of the spleen was noted in 11 cases, and of the pancreas, in six. All these six also showed increased value for the spleen; the amount of blood transfusion was less than 40 units in three case and more than 40 units in the other three. None showed glucose intolerance. Between the two groups, there were no statistically significant difference in the amount and duration of transfusion, or blood ferritin level. CONCLUSION: There is no correlation between the CT features of hemosiderosis and clinical findings. In patients with chronic renal failure and no clinical symptoms, the status of iron overload was relatively easily detected on CT. Close observation of CT findings is thus thought to prevent significant permanent functional deformity of organs in patients with chronic renal failure who have received multiple blood transfusions.