Gating provides improved accuracy for differentiating artifacts from true lesions in equivocal fixed defects on technetium 99m tetrofosmin perfusion SPECT.
BACKGROUND
Because equivocal fixed perfusion defects on single photon emission computed tomography (SPECT) often cause a diagnostic dilemma in patients with suspected coronary artery disease (CAD), we used receiver-operating characteristic (ROC) curve analysis to evaluate the degree of increased accuracy provided by adding gated images for interpretation of such cases.


RESULTS
One hundred five (29%) of 365 consecutive patients undergoing technetium 99m tetrofosmin gated SPECT for evaluation of CAD demonstrated an equivocal fixed defect. Two independent observers graded the probability for true lesion with a 5-point system over 3 steps of interpretation: reviewing tomographic images alone (step 1), adding projection images (step 2), and adding gated cine images (step 3). Based on clinical criteria, 66 patients were categorized as disease negative and 25 as disease positive, while the final diagnosis was undetermined in 14 cases. Diagnostic performance was significantly higher at step 3 than at step 1 for both observers (p < 0.05 and < 0.0001) and at step 2 for observer B (p < 0.005). The maximum accuracy increased from 78.0% to 80.2% at step 2 to 84.6% to 86.8% at step 3. Moreover, the agreement of interpretation between the 2 observers was higher at step 3 (kappa = 0.53) than at step 1 (kappa = 0.29) or step 2 (kappa = 0.25).


CONCLUSIONS
In patients showing an equivocal fixed defect on 99mTc tetrofosmin SPECT, gated cine images provide improved differential accuracy and enhanced objectivity of interpretation by reducing interobserver variance.
Department of Nuclear Medicine and Cardiovascular Institute, Sung Kyun Kwan University College of Medicine, Samsung Medical Center, Seoul, Korea.
J Y
JY
Choi
K H
KH
Lee
S J
SJ
Kim
S E
SE
Kim
B T
BT
Kim
S H
SH
Lee
W R
WR
Lee
D016477:Artifacts; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000453:epidemiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods* / Q000706:statistics & numerical data
D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; C078700:technetium tc-99m tetrofosmin