Purpose: To determine the stability and quality of MR temperature mapping using the proton resonance frequency (PRF) method in the liver of hepatic tumor patients.Material and Methods: The standard deviation of a series of temperature maps was determined in 30 patients (21 cirrhotic livers with carcinoma, 9 non-cirrhotic livers with metastasis or angioma) and in 5 volunteers at normal body temperature under free breathing. A respiratory-gated segmented EPI sequence (3 slices in 1 expiration phase) was performed with SENSE acceleration on a 1.5 T scanner. Motion corrupted images were identified by calculation of the cross-correlation coefficient and discarded.Results: A T 2* range of 10-33 ms was found with especially low values in advanced cirrhotic livers. The mean temperature standard deviation in patients was 2.3°C (range 1.5-5.0°C). The stability in healthy livers was slightly better than that in cirrhotic livers, and it was higher in the right than in the left liver. The gaiting failed in 4 % of the images when the respiratory cycle was irregular, leading to motion artifacts and errors in the temperature maps.Conclusion: The achieved temperature stability and image quality makes real-time quantitative monitoring of thermal ablation of liver tumors feasible on a clinical scanner.Read less <