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Large variation in blood flow between left ventricular segments, as detected by adenosine stress dynamic CT perfusion
Jakob De Geer1, Marcus Gjerde2, Lars Brudin3
1Faculty of Health Sciences, Department of Medical and Health Sciences, Department of Radiology in Linköping, Center for Medical Image Science and Visualization (CMIV), Linköping University, County Council of Östergötland, Linköping, Sweden.
Insights
Dynamic cardiac CT perfusion (CTP) shows a weak correlation with SPECT for assessing blood flow. Significant variations in CTP measurements indicate its current limitations for detecting ischemic segments.
Area of Science:
- Cardiovascular Imaging
- Radiology
- Nuclear Medicine
Background:
- Dynamic cardiac CT perfusion (CTP) is an emerging imaging technique.
- It requires further validation for clinical use.
Purpose of the Study:
- To compare dynamic CTP blood flow during adenosine stress with (99m) Tc SPECT.
- To evaluate manual versus automatic segmentation in CTP analysis.
Main Methods:
- Seventeen patients with coronary artery disease underwent dynamic stress CTP and stress/rest SPECT.
- CTP blood flow was analyzed per segment and compared to SPECT.
- Manual and automated segmentation results were compared.
Main Results:
- CTP demonstrated a positive but weak correlation with SPECT (r=0.38-0.41, P<0.0001).
- No significant difference was found between manual and automated segmentation correlations.
- Significant variations in CTP blood flow values were observed within and across patients.
Conclusions:
- A weak correlation exists between dynamic CTP and SPECT for myocardial blood flow.
- High variability in CTP measurements suggests limitations in detecting ischemic segments using cut-off values.
- Limited coverage of dynamic CTP impacts its diagnostic utility.
Background:
Dynamic cardiac CT perfusion (CTP) is based on repeated imaging during the first-pass contrast agent inflow. It is a relatively new method that still needs validation.
Purpose:
To evaluate the variation in adenosine stress dynamic CTP blood flow as compared to (99m) Tc SPECT. Secondarily, to compare manual and automatic segmentation.
Methods:
Seventeen patients with manifest coronary artery disease were included. Nine were excluded from evaluation for various reasons. All patients were examined with dynamic stress CTP and stress/rest SPECT. CTP blood flow was compared with SPECT on a per segment basis. Results for manual and automated AHA segmentation were compared.
Results:
CTP showed a positive correlation with SPECT, with correlation coefficients of 0·38 and 0·41 for manual and automatic segmentation, respectively (P<0·0001). There was no significant difference between the correlation coefficients of the manual and automated segmentation procedures (P = 0·75). The average per individual global CTP blood flow value for normal segments varied by a factor of 1·9 (manual and automatic segmentation). For the whole patient group, the CTP blood flow value in normal segments varied by a factor of 2·9/2·7 (manual/automatic segmentation). Within each patient, the average per segment blood flow in normal segments varied by a factor of 1·3-2·0/1·2-2·1 (manual/automatic segmentation).
Conclusion:
A positive but rather weak correlation was found between CTP and (99m) Tc SPECT. Large variations in CTP blood flow suggest that a cut-off value for stress myocardial blood flow is inadequate to detect ischaemic segments. Dynamic CTP is hampered by a limited coverage.