[Double-dose Gd-DTPA: detectability of intraparenchymal brain metastasis]

The aim of this study was to assess the efficacy of double-dose (0.2 mmol/kg cumulative dose) gadopentetate dimeglumine (Gd-DTPA) in patients with intraparenchymal brain metastasis.

We studied 119 patients using an incremental-dose technique. After precontrast T1- and T2-weighted spin-echo studies were performed, each patient received an initial injection of 0.1 mmol/kg body weight and an additional dose of 0.1 mmol/kg 6-8 minutes later.

Fifty-five cases (65 examinations) showed abnormal findings suggestive of intraparenchymal metastatic brain tumor and were included in the efficacy analysis. More enhancing lesions were detected with double-doses than with a single dose in 39 of 65 examinations (60%). With a single dose of Gd-DTPA. 562 definite and 111 equivocal lesions were found in brain parenchyma, and with an additional dose. 923 definite and 145 equivocal lesions were detected. In three cases, intraparenchymal metastatic brain tumors were detected only with double doses, and in five cases the lesion was solitary with a single dose but multiple after double doses. Based on our results. MR imaging with double doses had a statistical advantages over 0.1 mmol/kg examination in detecting early and/or small metastases. There is no statistical difference between at 0.5T and 1.0-1.5T in improving detectability of metastatic brain tumors after a double dose. We have not experienced any adverse effects of Gd-DTPA in this patient series.

In surveying brain metastatsis, contrast-enhanced MR imaging with double doses is more useful in detecting lesions than with a single dose of Gd-DTPA.