AJR 2004; 183:1469-1473
© American Roentgen Ray Society
Detection of Meniscal Tears and Marrow Lesions Using Coronal MRI
Thomas Magee1,2 and
David Williams1
1 Department of Radiology, Neuroskeletalimaging, 255 Sykes Creek Pkwy., Merritt
Island, FL 32953.
2 Department of Radiology, Neuroimaging Institute, 27 E Hibiscus Blvd.,
Melbourne, FL 32901.
Received March 9, 2004;
accepted after revision April 19, 2004.
Address correspondence to T. Magee
(tmageerad{at}cfl.rr.com).
Abstract
OBJECTIVE. The usefulness of coronal images in addition to sagittal
images for detection of additional meniscal injuries or bone lesions has been
questioned. Some authors believe meniscal tears are rarely seen only in the
coronal plane. We performed a retrospective review of coronal and sagittal MR
images of the knee to determine whether coronal imaging resulted in the
detection of any additional meniscal tears or bone lesions when compared with
sagittal MRI of the knee alone.
MATERIALS AND METHODS. Two musculoskeletal radiologists
retrospectively reviewed 200 consecutive sets of MR images of the knee by
consensus. Both observers recorded their retrospective findings on sagittal
proton density images, sagittal and coronal T2-weighted images, and coronal
T1-weighted images. Findings recorded were those of meniscal tears, bone
marrow abnormalities, and bone lesions.
RESULTS. On these 200 consecutive sets of MR images of the knee, 114
meniscal tears were shown. Ninety-three meniscal tears were shown on sagittal
proton density images only. One hundred fourteen meniscal tears were seen on
sagittal proton density and coronal T1- and T2-weighted images. Use of coronal
images resulted in the confident detection of 21 additional meniscal tears not
well seen on sagittal proton density images alone. Twelve of the 21 additional
meniscal tears were seen on coronal T1- and T2-weighted images. Nine of the 21
additional meniscal tears were seen only on coronal T1-weighted images. Most
of these additional meniscal tears were in the body of the meniscus. These 21
additional meniscal tears were confirmed arthroscopically. Eight marrow
lesions were well characterized only on coronal T1-weighted images. Five were
osteochondral lesions, one was an intraosseous hemangioma, and two were
microfractures.
CONCLUSION. Coronal MR images of the knee allowed better detection
and characterization of some meniscal tears than sagittal images alone. Radial
meniscal tears, bucket-handle tears, and horizontal tears in the body of the
meniscus may be difficult to characterize in the sagittal plane alone. Use of
coronal T1-weighted images, rather than coronal T2-weighted or sagittal proton
density images alone, allows accurate characterization of some additional
marrow lesions. The addition of a T1-weighted sequence in the coronal plane
adds only 1 min 30 sec to the scanning time.
Introduction
MRI has been shown to be accurate in the detection and characterization of
meniscal tears
[1–4].
These studies did not separate the accuracy of meniscal tear detection in the
sagittal rather than the coronal MRI plane. Some authors
[5] have stated that virtually
all meniscal tears are detected and characterized on sagittal plane imaging
only. Kaplan et al. [6] have
stated that obtaining short TE sequences of the knee in the coronal plane is
unnecessary because no additional significant information regarding meniscal
tears or marrow lesions is attained. To our knowledge, there has been no
published study indicating whether coronal MR images, and specifically
short-TE coronal images, of the knee allow more sensitive and specific
detection and characterization of meniscal tears or marrow lesions. Studies
indicating that coronal MR images of the knee may be useful for some specific
findings, such as radial meniscal tears
[7], loss of articular
cartilage [8,
9], and collateral ligament
injuries [10], have been
published.
We undertook a retrospective review of 200 consecutive sets of MR images of
the knee to determine whether coronal MR images yielded additional information
regarding meniscal tears or marrow lesions when compared with sagittal
images.
Materials and Methods
Two hundred consecutive sets of MRI examinations of the knee performed
between June and July 2003 at our institution were reviewed retrospectively.
The age range of the 200 patients was 12–73 years (mean, 41 years).
All patients underwent MRI of the knee in coronal, axial, and sagittal
planes on a 1.5-T Symphony scanner (Siemens Medical Solutions). Coronal turbo
spin-echo T1-weighted (TR/TE, 749/10), coronal and sagittal turbo spin-echo
fat-saturated T2-weighted (3,950/51), proton density sagittal (1,800/12), and
T2-weighted fast low-angle shot axial (905/18) images, with fields of view of
15 cm on coronal and sagittal images and 16 cm on axial images, were used.
Slice thickness on each sequence was 4 mm with a 10% interslice gap. All MRI
sequences had an image matrix of 256 x 192. A quadrature extremity coil
was used.
Two musculoskeletal radiologists retrospectively reviewed by consensus the
200 consecutive MRI examinations of the knee. One hundred forty-two of the 200
patients had undergone arthroscopy. Findings recorded were those of meniscal
tears, bone marrow abnormalities, and bone lesions. Meniscal tears were
defined as areas of abnormal intrameniscal signal extending to an articular
surface or truncation or abnormal morphology of the meniscus. Both observers
recorded retrospective findings on each of the following: sagittal proton
density sequences, sagittal T2-weighted images, and coronal T1- and
T2-weighted images. Retrospective consensus analysis of meniscal tears was
performed with evaluation of sagittal images only on one interpretation and
with evaluation of sagittal and coronal images together at a separate
interpretation. Consensus interpretation was achieved when both observers
agreed that a meniscal tear or bone lesion was present or absent on an MR
image.
Statistical analysis of sensitivity and specificity for detection of
meniscal tears on MRI compared with arthroscopy was performed. The sensitivity
and specificity of sagittal MRI alone were compared with those of sagittal and
coronal MRI together.
Results
In these 200 consecutive MRI examinations, 114 meniscal tears were shown.
Ninety-three meniscal tears were shown on sagittal proton density images only.
One hundred fourteen meniscal tears were shown on sagittal proton density and
coronal T1- and T2-weighted images. Use of coronal images resulted in the
detection of 21 additional meniscal tears not seen on proton density sagittal
images alone. Nine of the 21 additional meniscal tears were seen only on
coronal T1-weighted images. These nine additional meniscal tears were
horizontal tears in the body of the meniscus (Figs.
1A,
1B and
2A,
2B). Twelve of the 21
additional meniscal tears were seen on coronal T1- and T2-weighted images. Of
the 12 meniscal tears seen on both coronal T1- and T2-weighted images, 10 were
radial meniscal tears well seen only on the coronal plane and two were
bucket-handle meniscal tears well characterized only in the coronal plane
(Figs. 3A,
3B and
4A,
4B,
4C). All 21 additional meniscal
tears were confirmed arthroscopically. The sensitivity of sagittal MR images
of the knee alone, compared with arthroscopy, was 77%. Ninety-three meniscal
tears were seen with sagittal MRI of the knee only, compared with 121 meniscal
tears seen on arthroscopy. The sensitivity of sagittal and coronal MR images,
compared with arthroscopy, was 94%. One hundred fourteen meniscal tears were
seen on sagittal and coronal MRI of the knee, compared with 121 meniscal tears
seen on arthroscopy. In this series, no false-positive interpretations of
meniscal tears were made on MRI, unlike with arthroscopy.
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Fig. 2A. —42-year-old woman with knee pain and surgically proven
meniscal tear. Coronal turbo spin-echo T1-weighted MR image (TR/TE, 749/10)
shows findings consistent with meniscal tear (arrow).
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Fig. 2B. —42-year-old woman with knee pain and surgically proven
meniscal tear. Sagittal proton density MR image (1,800/12) shows
intrasubstance signal but no evidence of meniscal tear (arrow).
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Fig. 3A. —44-year-old man with knee pain and surgically proven radial
meniscal tear. Coronal T2-weighted MR image (TR/TE, 3,050/105) shows linear
area of abnormal increased signal in body of meniscus consistent with radial
tear (arrow).
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Fig. 4A. —39-year-old woman with knee pain and surgically proven
bucket-handle meniscal tear. Coronal turbo spin-echo T1-weighted MR image
(TR/TE, 749/10) shows findings consistent with bucket-handle tear
(arrow). In original MRI report, this was described as displaced
meniscal flap tear, but at arthroscopy it was described as displaced meniscal
bucket-handle tear.
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Fig. 4B. —39-year-old woman with knee pain and surgically proven
bucket-handle meniscal tear. Coronal T2-weighted MR image (3,050/105) shows
findings consistent with meniscal bucket-handle tear (arrow).
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Eight marrow lesions were well characterized only on coronal T1-weighted
images. Five were osteochondral lesions, one was an intraosseous hemangioma,
and two were microfractures (Figs.
5A,
5B,
6A,
6B,
7A,
7B,
8A,
8B).
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Fig. 6A. —12-year-old boy with knee pain. Coronal turbo spin-echo
T1-weighted MR image (TR/TE, 749/10) shows findings consistent with
microfracture of tibia (thin arrow) and avulsion of epiphysis
(thick arrow).
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Discussion
Coronal MR images allowed confident detection of some additional meniscal
tears not well characterized on sagittal proton density images alone. Twelve
of these were seen on coronal T1- and T2-weighted images. Of these 12, 10 were
radial meniscal tears that were seen only in the coronal plane. Depending on
the orientation of radial tears, they may be seen only in the coronal plane
because they are often small. The sagittal proton density sequences used in
this study were 4 mm thick. Small radial tears may be subject to volume
averaging with adjacent structures, making them difficult to see.
Two bucket-handle meniscal tears were well characterized on coronal images
only. In these two cases, a bucket-handle fragment was displaced into the
intracondylar region and on sagittal images was not well seen presumptively
because of volume averaging with the surrounding soft tissues.
Nine of twenty-one meniscal tears seen on coronal images were well seen
only on coronal T1-weighted images. All of these were horizontal tears in the
body of the meniscus. In all cases, intrasubstance signal could be seen on
sagittal images but a definitive diagnosis of meniscal tear (i.e., abnormal
signal touching an articular surface) could not be made. These tears were most
likely not well seen on sagittal images because of the orientation of such
tears and volume averaging.
Coronal T1-weighted images allowed more accurate characterization of some
marrow lesions not well shown on coronal T2-weighted or sagittal proton
density images alone. Five osteochondral injuries or defects were better
characterized on T1-weighted sequences, presumptively because such lesions
were sub-acute or old with no marrow edema shown in that area on fat-saturated
T2-weighted sequences. Two microfractures were better characterized on coronal
T1-weighted sequences. A linear area of dark signal on T1-weighted sequences
clearly showed a microfracture in these cases. On fat-saturated T2-weighted
sequences, diffuse nonspecific marrow edema was shown. One patient had an
intraosseous hemangioma better characterized on T1-weighted sequences than on
fat-saturated T2-weighted sequences.
In our practice, most referrals for MRI examinations of the knee come from
orthopedic surgeons, which may result in a high prevalence of positive
findings. This high prevalence of positive findings in our practice may
increase the importance of added sensitivity from coronal imaging in the
detection of meniscal tears, when compared with a population with a low
prevalence of positive findings.
Proton density–weighted coronal images are commonly used for
detection of meniscal tears and osteochondral injuries. In our practice, we
use coronal T1-weighted images for this purpose because the imaging time for
T1-weighted imaging is significantly less than for proton
density–weighted imaging.
In conclusion, coronal MR images of the knee allow better detection and
characterization of some meniscal tears than do sagittal images alone.
Meniscal tears that may be difficult to characterize in the sagittal plane
alone include radial meniscal tears, bucket-handle tears, and horizontal tears
in the body of the meniscus. Coronal T1-weighted images allow more accurate
characterization of some additional marrow lesions not well characterized on
fat-saturated T2-weighted sequences. The addition of a coronal T1-weighted
image adds only 1 min 30 sec to the scanning time.
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Abstract
Introduction
