Preliminary In Vivo Validation of a Dedicated Breast MRI and Sonographic Coregistration Imaging System
Petrina A. Causer1,
Cameron A. Piron2,
Roberta A. Jong1 and
Donald B. Plewes3
1 Department of Medical Imaging, Sunnybrook Health Sciences Centre, University
of Toronto, 2075 Bayview Ave., MG166, Toronto, ON, M4N 3M5, Canada.
2 Sentinelle Medical, Toronto, ON, Canada.
3 Departments of Imaging Research and Medical Biophysics, Sunnybrook Health
Sciences Centre, University of Toronto, Toronto, ON, Canada.
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Fig. 1A —MRI–sonography coregistration system, prepared for MRI
and sonography. Photograph shows redesigned patient support and breast imaging
table set up for MRI. Table is docked in place of standard imaging table.
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Fig. 1B —MRI–sonography coregistration system, prepared for MRI
and sonography. Photograph shows redesigned patient support and breast imaging
table set up for MRI. Open aperture, covered by thin sonography-compatible
membrane (asterisk), allows ultrasound transducer access to image
breast. Breast MR receiver coil (arrow) is removable once MRI is
complete.
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Fig. 1C —MRI–sonography coregistration system, prepared for MRI
and sonography. Photograph shows MRI–sonography coregistration imaging
system set up for sonography. Outside magnet, MR coil is exchanged for
ultrasound transducer positioning stage (arrow). Once stage is set
according to calculated 5 df based on position of MRI target lesion,
ultrasound transducer is placed on stage (arrowhead).
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Fig. 2A —MRI–sonography coregistration images in 50-year-old
asymptomatic woman at high risk who presented with BI-RADS category 5 mass in
left breast detected on MRI screening examination, corresponding to invasive
ductal carcinoma. Sagittal fat suppressed T1-weighted 2D spoiled
gradient-recalled acquisition in steady-state MR image (TR/TE, 150/4.2) of
left breast shows 9-mm enhancing lobulated mass with irregular margins
(arrow) corresponding to target MRI mass lesion.
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Fig. 2B —MRI–sonography coregistration images in 50-year-old
asymptomatic woman at high risk who presented with BI-RADS category 5 mass in
left breast detected on MRI screening examination, corresponding to invasive
ductal carcinoma. Coregistered coronal sonogram shows irregular mass
(arrow) that is isoechoic to fat, with similar size and location from
the MRI calculated position. Echogenic fibroglandular tissue interfaces with
more hyperechoic fat surrounding mass are indicated by arrowheads and are
similar to those visible on coronal MR image in C. Measured three-plane
error from sonogram in this case was x error = 1.6 mm, y
error = 1.8 mm, and z error = -1.4 mm.
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Fig. 2C —MRI–sonography coregistration images in 50-year-old
asymptomatic woman at high risk who presented with BI-RADS category 5 mass in
left breast detected on MRI screening examination, corresponding to invasive
ductal carcinoma. Coronal T1-weighted 2D fast spoiled gradient-recalled echo
MR image (150/4.2) shows same mass (arrow) as in A and
B. Arrowheads indicate low-signal fibroglandular interfaces with
surrounding high-signal-intensity fat and are similar to those indicated on
sonogram in B. Breast parenchymal patterns were used in addition to
similar mass size to ensure lesion correlation between sonography and MRI.
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Fig. 3A —MRI–sonography coregistration images in 65-year-old
woman who presented initially with mass on mammography, confirmed as cyst on
sonography. Sagittal fat-suppressed T2-weighted fast spin-echo MR image
(TR/TE, 3,000/102) of left breast shows 8-mm cyst (arrow)
corresponding to target MRI lesion.
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Fig. 3B —MRI–sonography coregistration images in 65-year-old
woman who presented initially with mass on mammography, confirmed as cyst on
sonography. Coronal sonogram of MRI cystic target lesion (arrow),
obtained by positioning ultrasound transducer and stage according to
calculated stage position coordinates based on MRI; x (superoinferior
with respect to the patient) and z (depth from skin) directions are
shown on sonogram. Because lesion was anticipated to be centered in image,
x and z measurement errors were measured on sonogram, taking
difference between center of sonogram (asterisk) and actual center of
lesion displayed (circle) in both directions. Registration error was
measured in this case as x = 4 mm, y = 1 mm, and z
= 2.5 mm.
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Fig. 3C —MRI–sonography coregistration images in 65-year-old
woman who presented initially with mass on mammography, confirmed as cyst on
sonography. Coronal T1-weighted 2D fast spoiled gradient-recalled echo MR
image (150/4.2) of same cyst (arrow) as in A and B.
Coordinates of center of cyst (asterisk) were obtained to calculate
expected lesion position on sonography. In addition to lesion identification
on both MRI and sonography, breast parenchymal interfaces on coronal sonograms
and MR images (B) were identified to ensure lesion correlation. Amount
of fat between lesion and skin surface was measured as 11 mm in this case, as
shown, to calculate expected error introduced in z-plane by
differential speed of sound through fat compared with fibroglandular
tissue.
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Copyright © 2008 by the American Roentgen Ray Society.
