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Septal perfusion and wall thickening in patients with left bundle branch block assessed by technetium-99m-sestamibi
H Sugihara1, N Tamaki, M Nozawa
1Takashima General Hospital, Shiga-ken, Japan.
Insights
Septal hypoperfusion in left bundle branch block (LBBB) patients on myocardial perfusion imaging can be an artifact. ECG-gated sestamibi SPECT, especially end-diastolic images, can eliminate this artifact caused by reduced wall thickening.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Septal hypoperfusion is a common finding in patients with complete left bundle branch block (LBBB) during myocardial perfusion imaging.
- Abnormal septal wall motion in LBBB can lead to artifactual perfusion abnormalities.
- Assessing the impact of wall thickening on myocardial perfusion imaging is crucial for accurate diagnosis.
Purpose of the Study:
- To evaluate the effect of abnormal wall thickening on myocardial perfusion images in patients with LBBB.
- To determine if ECG-gated sestamibi SPECT can differentiate true hypoperfusion from artifact in LBBB patients.
Main Methods:
- 12 patients with LBBB and 10 normal subjects underwent rest ECG-gated sestamibi SPECT.
- 740 MBq of 99mTc-sestamibi was injected at rest, with SPECT imaging 60 minutes later.
- Cardiac cycle was divided into eight frames for gated analysis.
Main Results:
- Septal hypoperfusion was observed in 10/12 LBBB patients on nongated and 11/12 on end-systolic (ES) images, but only 2/12 on end-diastolic (ED) images.
- The septal to lateral wall count ratio was lower in LBBB patients (0.72) vs controls (0.84) on nongated images (p < 0.01), but similar on ED images (p > 0.05).
- Reduced septal wall thickening (25% count increase ED-ES) in LBBB patients compared to the lateral wall (48%) and controls (p < 0.01).
Conclusions:
- Reduced septal wall thickening in LBBB patients can mimic myocardial hypoperfusion on standard imaging.
- ECG-gated 99mTc-sestamibi SPECT, particularly using ED images, effectively eliminates this artifact.
- This technique improves the accuracy of myocardial perfusion assessment in LBBB patients.
Unlabelled:
Septal hypoperfusion is often observed in patients with complete left bundle branch block (LBBB) in myocardial perfusion imaging. Abnormal wall motion in the septal region may potentially cause artifactual perfusion abnormalities. To assess the effect of abnormal wall thickening on myocardial perfusion images, ECG-gated sestamibi SPECT was performed on 12 patients with LBBB and 10 normal subjects used as controls.
Methods:
After administration of 740 MBq 99mTc-sestamibi injection at rest, ECG-gated SPECT was obtained 60 min later with division of the cardiac cycle into eight frames.
Results:
Septal hypoperfusion was noted in 10 patients on nongated images and 11 patients on end-systolic (ES) images, whereas only two patients showed abnormalities on end-diastolic (ED) images. The septal to lateral wall count ratio in the LBBB group was lower (0.72 +/- 0.09) than in the control group (0.84 +/- 0.09) (p < 0.01) at nongated images, while it was similar at ED images (0.84 +/- 0.11 versus 0.86 +/- 0.12; ns). In addition, the count increase from ED to ES during a cardiac cycle in the septal region was smaller compared with the lateral region in the LBBB patients (25% +/- 19% in the septal region, versus 48% +/- 14% in the lateral region; p < 0.01), indicating less wall thickening in the septal region.
Conclusion:
Smaller count increase due to reduced wall thickening in the septal region may mimic hypoperfusion in patients with LBBB. This artifact can be eliminated with ECG-gated 99mTc-sestamibi SPECT, particularly with ED images.