Purpose: To test whether a new quantitative measure, the tumor-to-vessel ratio, obtained from late post-iron-oxide-enhanced T1-weighted images allows for differentiating hemangiomas from liver metastases or all malignant liver lesions.
Material and Methods: Twenty-six patients (mean 57, range 33–79 years) were prospectively studied at 1.5T magnetic resonance imaging (MRI) with a T1-weighted 2D fast low-angle shot (FLASH) sequence (repetition time/echo time/flip angle; 200 ms/4.8 ms/90°) and a T2-weighted turbo spin-echo sequence (4072 ms/99 ms/180°). Imaging was carried out before and at intervals up to 18 min after IV injection of Ferucarbotran (Resovist®, Schering, Germany). In 19 patients, one representative malignant lesion was analysed. Eleven hemangiomas were evaluated in 7 patients. Two readers performed a consensus reading with a signal intensity measurement in a lesion, normal liver and hepatic veins, from which ratios were computed.
Results: On T1-weighted iron-oxide-enhanced MRI of 30 lesions, tumor-to-vessel signal intensity ratios were distinct in hemangiomas (median 1.04, range 0.99–1.10) as opposed to either metastases (0.64, 0.33–0.77; P<0.05) or all malignant lesions taken together (0.64, 0.33–0.98; P<0.05), while the tumor-to-liver ratio was not.
Conclusion: The tumor-to-vessel ratio may help to differentiate between hemangiomas and metastases. A ratio greater than 0.98 allowed differentiating hemangiomas from metastases with a wide safety margin.
