EARLY DYNAMIC MAGNETIC-RESONANCE-IMAGING OF LIVER METASTASES WITH 0.3AND 0.6 MMOL KG GADOTERIDOL INJECTION/

RATIONALE AND OBJECTIVES. The potential for improvement in liver-lesio n conspicuity on early dynamic scans after bolus intravenous gadoliniu m (Gd) chelate administration was evaluated using gadoteridol (Gd-HP-D O3A; Prohance) at doses of 0.3 and 0.6 mmol/kg, METHODS. Five New Zeal and white rabbits with focal VX-2 adenocarcinoma liver metastases were studied on a 1.5-tesla Siemens Vision scanner, Each rabbit was imaged twice (on two separate days), after injections of 0.3 mmol/kg and 0.6 mmol/kg Gd-HP-DO3A. The contrast dose (0.3 or 0.6 mmol/kg) was given as a single intravenous injection. The order of injection for the two doses was randomized, with the two studies (in any one rabbit) separat ed by 24 hours to allow for clearance, Contrast was administered using an autoinjector at a rate of 1.5 mL/second, Turbo-fast low-angle shot scans were obtained before and at 6, 12, 19, 25, 31, 60, 120, 180, 24 0, 300, and 600 seconds after contrast injection, The lesions were con firmed, after killing the rabbit, by gross and microscopic examination , RESULTS. The enhancement of normal liver parenchyma, assessed by (SI t - SIo)/SIo . 100, (SI = signal intensity) peaked at 32% +/- 4% 19 se conds after injection of 0.3 mmol/kg and at 38% +/- 5% 31 seconds afte r injection of 0.6 mmol/kg, The difference in maximum parenchymal enha ncement achieved, comparing the 0.3 and 0.6 mmol/kg doses, was statist ically significant (P < 0.03), Lesion conspicuity, specifically (SIliv er - SIlesion/noise), increased from 4.5 +/- 2.3 precontrast to a maxi mum of 6.8 +/- 1.2 at 19 seconds postcontrast using a dose of 0.3 mmol /kg, with the difference statistically significant (P < 0.03), The inc rease with a dose of 0.6 mmol/kg was from 4.2 +/- 0.7 to 6.5 +/- 1.9, with this difference also statistically significant (P < 0.02), There was no statistically significant difference in lesion conspicuity betw een the doses of 0.3 and 0.6 mmol/kg. CONCLUSIONS. Conspicuity of live r metastases can be improved substantially with dynamic magnetic reson ance imaging and rapid intravenous bolus contrast injection with a dos e of 0.3 mmol/kg, No further improvement is noted at a dose of 0.6 mmo l/kg, despite greater positive contrast enhancement of normal liver pa renchyma.