Background: Although many investigators have evaluated the accuracy
of ultrasonography and magnetic resonance imaging for the detection of full
and partial-thickness rotator cuff tears, few have directly compared the two
tests. The purpose of our study was to compare the accuracy of the two tests
for detection and measurement of the size of rotator cuff tears, with
arthroscopic findings used as the standard.
Methods: One hundred and twenty-four consecutive patients with
shoulder pain were prospectively studied with ultrasonography and magnetic
resonance imaging. Seventy-one had subsequent arthroscopy, and they formed the
study group. The arthroscopic diagnosis was a full-thickness tear in forty-six
patients, a partial-thickness tear in nineteen, and no tear in six. The
presence or absence of a full or partial-thickness tear and the tear size as
demonstrated by each imaging test and at the time of arthroscopy were
recorded. The findings of the imaging tests and arthroscopy were then compared
for each parameter.
Results: Ultrasonography correctly identified forty-five of the
forty-six full-thickness tears and magnetic resonance imaging, all forty-six.
Ultrasonography correctly identified thirteen of the nineteen
partial-thickness rotator cuff tears and magnetic resonance imaging, twelve of
the nineteen. The overall accuracy for both imaging tests was 87%.
Ultrasonography correctly predicted the degree of retraction of 73% of the
full-thickness tears and the length of 85% of the partial-thickness tears, and
magnetic resonance imaging correctly predicted the retraction and length of
63% and 75%, respectively. Ultrasonography correctly predicted the width of
87% of the full-thickness tears and 54% of the partial-thickness tears, and
magnetic resonance imaging correctly predicted the width of 80% and 75%,
respectively. No significant differences between ultrasonography and magnetic
resonance imaging were demonstrated (p > 0.05).
Conclusions: Ultrasonography and magnetic resonance imaging had
comparable accuracy for identifying and measuring the size of full-thickness
and partial-thickness rotator cuff tears. When an investigator has comparable
experience with both imaging tests, the decision regarding which test to
perform for rotator cuff assessment does not need to be based on accuracy
concerns. The choice can be based on other factors, such as the importance of
ancillary clinical information (regarding lesions of the glenoid labrum, joint
capsule, or surrounding muscle or bone), the presence of an implanted device,
patient tolerance, and cost.
Level of Evidence: Diagnostic study, Level I-1 (testing
of previously developed diagnostic criteria in series of consecutive patients
[with universally applied reference "gold" standard]). See
Instructions to Authors for a complete description of levels of evidence.