1 On a T2-weighted MRI, which would appear hyperintense?
A) Fat
B) Blood in the carotid
C) Bone
D) Vitreous
2 A 30-year-old man was hit in his left eye at work and complains of sudden visual loss. You
measure his best acuity to be light perception in this eye. Ophthalmic examination is normal.
Which test does not rely on the patient’s interpretation of visual information?
A) Red/green spectacles
B) Optokinetic nystagmus (OKN) drum
C) Stereo acuity
D) Color vision
Answers-
1-D) Vitreous
MRIs allow excellent soft tissue definition by varying radiofrequency pulse sequences and
measuring the resulting signal produced by the tissue. T1- and T2-weighted MRIs are able to
highlight structures by the intensity of the signal generated after the magnetic pulse. Table 4-1
lists some of the differences between T1- and T2-weighted images. Air, fast-moving blood, and
bone generally produce no signal and are thus hypointense on the MRI. Fat and vitreous are
opposite to one another in both the T1- and T2-weightings.
2-B) Optokinetic nystagmus (OKN) drum
A number of tests can be used to determine whether a patient has functional visual loss. Direct
tests do not require the patient to verbally respond or interpret the visual information. Tests
such as the swinging light test, OKN response, and mirror test make it very difficult for a patient
to feign disease. Indirect tests rely on the patient’s cooperation and allow more definite
measurement of visual acuity in the “injured” eye.
A) Fat
B) Blood in the carotid
C) Bone
D) Vitreous
2 A 30-year-old man was hit in his left eye at work and complains of sudden visual loss. You
measure his best acuity to be light perception in this eye. Ophthalmic examination is normal.
Which test does not rely on the patient’s interpretation of visual information?
A) Red/green spectacles
B) Optokinetic nystagmus (OKN) drum
C) Stereo acuity
D) Color vision
Answers-
1-D) Vitreous
MRIs allow excellent soft tissue definition by varying radiofrequency pulse sequences and
measuring the resulting signal produced by the tissue. T1- and T2-weighted MRIs are able to
highlight structures by the intensity of the signal generated after the magnetic pulse. Table 4-1
lists some of the differences between T1- and T2-weighted images. Air, fast-moving blood, and
bone generally produce no signal and are thus hypointense on the MRI. Fat and vitreous are
opposite to one another in both the T1- and T2-weightings.
2-B) Optokinetic nystagmus (OKN) drum
A number of tests can be used to determine whether a patient has functional visual loss. Direct
tests do not require the patient to verbally respond or interpret the visual information. Tests
such as the swinging light test, OKN response, and mirror test make it very difficult for a patient
to feign disease. Indirect tests rely on the patient’s cooperation and allow more definite
measurement of visual acuity in the “injured” eye.
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