Noise correlation.

Abstract:

:Calculations and experiments that provide support for our previously stated theorem are presented: If two coils simultaneously receiving magnetic resonance signals from the same anatomic region exhibit zero mutual inductance, there can be no correlation of the noise. It is shown that correlation does not exist even in the presence of mutual inductance unless the two signal paths have amplifiers prior to signal combination. It is further found that in the presence of mutual inductance with ideal amplifiers (0 dB noise figure) in the two signal paths, there is no correlation of noise. In order to satisfy the condition of zero mutual inductance, it may be necessary to employ a decoupling circuit external to the body. A novel coil assembly, which was used in the experiments, places a single-turn surface coil in the median plane between the two loops of a counter rotating current coil. The signal-to-noise ratio can be improved by combining signals. This is in analogy to quadrature receiving coils, where the mutual inductance is zero because vector reception fields are perpendicular. In the present geometry, vector reception fields are collinear, but are parallel and antiparallel on the two sides of the coil assembly, resulting in zero mutual inductance.

journal_name

Magn Reson Med

authors

Jesmanowicz A,Hyde JS,Froncisz W,Kneeland JB

doi

10.1002/mrm.1910200105

subject

Has Abstract

pub_date

1991-07-01 00:00:00

pages

36-47

issue

1

eissn

0740-3194

issn

1522-2594

journal_volume

20

pub_type

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