Abstract:
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Purpose: Multiple Sclerosis (MS) plaques are best demonstrated with MRI
using FLAIR sequences. Patient management decisions are often based on the
plaque load and the degree of plaque enhancement. This study was undertaken to
assess whether plaque load and the enhancement characteristics of MS plaques
are the same if measured using high and low field strength magnets.
Methods and Materials: Patients with MS scheduled for a high field (1.5T) MRI
scan of the brain with contrast were considered eligible for this study. After
giving their informed consent, patients were also scanned with contrast at low
field strength (0.2T). For their high field exam, patients received a standard
0.1 mmol/kg dose of gadopentetate dimeglumine (Magnevist, Berlex Labs, Wayne, NJ).
For their low field exam, patients were given a standard 0.1 mmol/kg dose of
gadoteridol (ProHance, Bracco Diagnostics Inc, Princeton, NJ) followed at 15
minutes by a second 0.1 mmol/kg dose of gadoteridol. Plaque volume was measured
using a computational program as well as by direct comparison by two
experienced neuroradiologists.
Results: Twenty patients were enrolled in the study. Plaque volume on FLAIR
imaging was not statistically different on low field versus high field imaging,
based both on automated calculation of plaque volume and on comparison review
by two neuroradiologists. However, in those patients with active plaques
showing enhancement the intensity of enhancement after a standard 0.1 mmol/kg
dose was less at low field strength than at high field strength. With a double
dose of contrast (0.2 mmol/kg) at low field strength, enhancement intensity was
similar to that seen with single dose enhancement at high field strength.
Conclusion: The volume of MS plaques on FLAIR MR imaging is similar at both low
and high field strength. However, standard dose contrast enhancement at low
field strength is inferior to standard dose at high field strength. Double dose
contrast is required at low field strength to achieve a similar enhancement
intensity as seen at high field strength with standard dose. These findings
have management implications for patients with MS, especially if they receive
scans at different field strengths. (R.G.B. is a speaker for and received a
grant from Bracco Diagnostics.)
Questions about this event email: barrr@attglobal.net
Barr MD, PhD, R,
Comparison of Multiple Sclerosis Plaque Volume on Low and High Field Enhanced MRI. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3106281.html
