Left ventricular wall motion abnormalities as well as reduced wall thickness can cause false positive results of...

Area of Science:

• Cardiology
• Nuclear Medicine
• Diagnostic Imaging

Background:

• The accuracy of single-photon emission computed tomography (SPECT) for detecting myocardial infarction is debated, particularly regarding false positives caused by non-ischaemic factors.
• Regional wall motion abnormalities and reduced wall thickness can mimic infarcts on SPECT imaging.

Purpose of the Study:

• To systematically evaluate the relationship between myocardial wall thickness, wall motion, and SPECT results for myocardial infarction detection.
• To determine if non-ischaemic wall motion abnormalities and reduced wall thickness lead to false positive SPECT findings.

Main Methods:

• Patients with left bundle branch block (LBBB) and no coronary artery disease (CAD) were analyzed using resting SPECT and cardiovascular magnetic resonance (CMR).
• SPECT findings were compared to CMR as the gold standard to identify false positive defects.
• A 72-segment model was used to correlate SPECT defects with wall motion and wall thickness abnormalities.

Main Results:

• All 19 patients without CAD showed fixed defects on SPECT, interpreted as myocardial infarction by observers.
• CMR confirmed that none of these SPECT defects represented actual myocardial infarcts.
• A strong correlation was found between SPECT defects and areas of abnormal wall motion (93% of dyskinetic segments were false positive) and reduced wall thickness (93% of segments 2 SD below mean thickness were false positive).

Conclusions:

• Abnormal myocardial wall motion and thickness can cause false positive results in resting SPECT myocardial perfusion imaging.
• These findings are significant in the absence of myocardial infarct scars and coronary artery disease.
• SPECT interpretation for myocardial infarction requires careful consideration of regional wall motion and thickness.