Case 12

Published on 02/03/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

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Case 12

A 65-year-old woman presents with recent onset of nonexertional chest pain. She has no coronary disease risk factors. She is referred for SPECT MPI.

She exercised on a Bruce protocol to a maximal workload of 10 METs. Peak heart rate was 155 beats/min (100% of maximal age-predicted heart rate). No exercise-induced symptoms were reported, and the blood pressure and ECG responses were normal.

Raw Planar Images

The rotating raw planar images demonstrate a prominent shadow produced by the right breast, but no left breast shadow is present. This patient has a history of breast cancer, and her prior treatment included left mastectomy. Mild patient motion is also present, and moderate GI tracer interference is evident on resting images.

SPECT Images

The poststress SPECT images demonstrate a mild defect in the inferior and inferolateral regions. Minimal defect reversibility is evident on resting images, suggestive of ischemia (but possibly the result of GI tracer interference). The perfusion pattern (highest tracer activity in the anterior and anterolateral regions, with relatively reduced activity in the inferior region) is a typical pattern in men. However, this perfusion pattern is not typical for a normal woman.

Quantitative Polar Maps

When the perfusion pattern is compared to a female-specific normal database, the perfusion in the inferior and inferolateral regions is identified as abnormal. Despite visually apparent defect reversibility, no significant reversibility was identified by quantitative assessment. The predominantly fixed perfusion defects could be consistent with prior infarction or soft-tissue attenuation artifact.

Gated SPECT Images

The poststress gated SPECT images demonstrate normal myocardial systolic thickening in all regions, with a computed LVEF of > 70%. These findings favor soft-tissue attenuation artifact (rather than infarction) as the cause of the observed inferior and inferolateral defects.

Teaching Points: Left Mastectomy

1 In women with left mastectomy, absence of the anterior attenuation produced by the left breast results in a male perfusion pattern (unopposed “diaphragmatic attenuation”).

2 Review of the raw planar images is important for identifying the absence of the left breast shadow.

3 Technologists should alert the interpreting physician to the history of left mastectomy.

4 In women with left mastectomy, use a male database for quantitative perfusion assessment.

Quantitative Polar Maps

When the perfusion pattern is compared to a male-specific normal database (right), the perfusion defects in the inferior and inferolateral regions are less extensive than the defects identified by comparison to the female-specific normal database (left). However, even compared to a male-specific normal database, the perfusion pattern remains mildly abnormal. Because of residual diagnostic uncertainty, confirmatory testing was performed (rubidium-82 PET MPI).

Quality-Control Display

The PET MPI quality-control display shows the rubidium-82 emission images (left), the germanium rod source transmission images (center), and an overlay of the emission and transmission images (right) to confirm proper registration (alignment). Note that the right breast is clearly identified on the transmission images, but the left breast is absent.

Dipyridamole Stress PET Images

The peak stress and resting PET images demonstrate normal rubidium-82 activity in all myocardial regions, including the inferior and inferolateral regions. PET MPI interpretation is less likely to be complicated by soft-tissue attenuation artifacts, because 100% of PET MPI studies are attenuation corrected.

Gated PET Images

The gated PET images demonstrate normal myocardial systolic thickening in all regions. The resting and peak stress LVEF was 57% and 63%, respectively. An increase in LVEF at peak dipyridamole stress (compared to resting LVEF) is commonly observed on gated PET imaging in the absence of ischemia. The ability to measure LVEF at rest and at peak stress (rather than after stress, as is done with gated SPECT) is a major advantage of PET MPI.

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