Magnetization transfer and high-dose contrast in early brain infection on magnetic resonance.
OBJECTIVE
The authors studied the effect of contrast dose, use of magnetization transfer (MT), and temporal delay on the visualization of contrast enhancement with gadoteridol (Gd HP-DO3A) in a canine brain abscess model.


METHODS
Alpha streptococcus brain abscesses were studied in five dogs at 1.5 tesla (T) 1 and 5 days after implantation. Scans were performed 1, 11, and 21 minutes after contrast was administered, using an initial dose of 0.1 mmol/kg. A supplemental contrast injection of 0.2 mmol/kg was given (for a cumulative dose of 0.3 mmol/kg), with scans repeated at 31, 41, and 51 minutes.


RESULTS
Lesion conspicuity on day 1 was greater at high-contrast doses (0.3 mmol/kg) compared with standard doses (0.1 mmol/kg), regardless of whether imaging was performed without (0.89 +/- 0.02 compared with 0.26 +/- 0.08) or with (0.97 +/- 0.04 compared with 0.28 +/- 0.06) MT. High-dose, MT, and a delay after contrast was injected all produced a statistically significant improvement. On blinded review of films obtained 11 and 14 minutes after injection, enhancement of the lesion could not be identified with certainty in two of five dogs at a dose of 0.1 mmol/kg, regardless of whether MT was used. Enhancement was seen consistently in all lesions at 0.3 mmol/kg. On day 5, results were comparable, with greater absolute enhancement.


CONCLUSIONS
In early brain infection, high-contrast doses (0.3 mmol/kg), MT, and a moderate delay after injection all improve visualization of lesion enhancement.
Runge
V M
VM
University of Kentucky, Lexington 40536-0098, USA.
Wells
J W
JW
Kirsch
J E
JE
D000818:Animals; D001922:Brain Abscess / Q000175:diagnosis*; D003287:Contrast Media / Q000008:administration & dosage; D004195:Disease Models, Animal; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005069:Evaluation Studies as Topic; D005682:Gadolinium / Q000008:administration & dosage; D006571:Heterocyclic Compounds / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D009942:Organometallic Compounds / Q000008:administration & dosage; D013997:Time Factors
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C062402:gadoteridol; D005682:Gadolinium