The Value of Attenuation Correction in Hybrid Cardiac SPECT/CT on Inferior Wall According to Body Mass Index

Comparison of positional artifacts in myocardial perfusion imaging in supine and semi-reclining position using dedicated D-SPECT cardiac camera: validation using CT based attenuation correction

BACKGROUND

Soft-tissue attenuation remains a major limitation of SPECT-MPI which interferes with the diagnosis of CAD. The current study aims to evaluate the pattern of attenuation artifacts in supine and semi-reclining positions on CZT cardiac camera and their interaction with gender, BMI and stress protocols.

METHODS

We prospectively analysed 150 patients acquired in supine and semi-reclining positions on CZT camera. The images were evaluated for severity and extent of defect using 17-segment model. An additional CT scan was acquired to generate AC image in the first 50 patients studied to assist investigator learning for comparison of artifact vs true defects in the two SPECT systems. The defects present in one position or showing change in severity within two positions were considered as positional artifacts and further validated using CTAC supine image.

RESULTS

In overall analysis, higher extent and severity of positional artifacts were observed more in semi-reclining position affecting the apex, apico-inferior, inferolateral and inferoseptal segments. Females showed more positional artifacts than males with inferior wall attenuation in the semireclining position and anterior wall attenuation in the supine position. A positive correlation of the extent and severity of positional artifacts was noted with an increasing BMI. In patients with BMI > 30, mid inferior and inferolateral segments were most affected followed by anterior wall segments. Highest correction of artifactual perfusion defects by CTAC was noted in inferior wall followed by inferolateral segments.

CONCLUSION

The incidence of positional artifacts was greater in semi-reclining position in females, higher BMI groups and adenosine stress subsets. Knowledge of the pattern of positional artifacts appears to be a reliable alternative of CTAC for correct interpretation of myocardial perfusion images.

Myocardial blood flows and reserves on solid state camera: Correlations with coronary history and cardiovascular risk factors

OBJECTIVES

Study designed to test association between stress-induced myocardial blood flow (sMBF), resting MBF (rMBF), and MBF reserve (MFR) and coronary artery disease (CAD) in a population of CAD and non-coronary patients. Secondary objectives were to confront visual analysis and dynamic analysis and to explore potential association between MBF and several cardiovascular risk factors METHODS: A total of 155 patients who underwent dynamic myocardial perfusion imaging on a CZT camera were included. sMBF, rMBF, and MFR were evaluated, and cardiovascular risk was assessed.

RESULTS

Significantly lower total sMBF and MFR were observed in CAD patient vs non-CAD patient. In comparison with visual analysis, lower sMBF were found in pathologic territory, lower rMBF in necrotic territory and lower MFR in necrotic ones. A significant correlation between total sMBF, rMBF and diabetes was found.

CONCLUSION

sMBF and MFR as assessed on CZT gamma-cameras can be used to determine the coronary state. Low total sMBF might be an independent risk factor of coronaropathy. An inverse correlation was suggested between total sMBF and rMBF with diabetes.

Impact of attenuation correction for CZT-SPECT measurement of myocardial blood flow

OBJECTIVES

Most of cardiac dedicated CZT-SPECT systems are not equipped with CT, whereas PET systems are. We evaluated the impact of AC correction on CZT-SPECT myocardial blood flow (MBF) and myocardial flow reserve (MFR) measurements.

METHODS

104 patients were included. SPECT data were acquired on cadmium zinc telluride (CZT)-based pinhole cardiac camera in listmode using a stress (250 ± 17 MBq)/rest (511 ± 23 MBq) 1-day Tc-99m-tetrofosmin protocol. Low-dose CT was acquired on another SPECT/CT camera in the same position. All analysis was performed using Corridor4DM.

RESULTS

Stress and rest MBF were significantly lower when AC was applied (P < 0.001). For regional and global MFR, there was no significant difference between AC and NAC measurements (P > 0.25 at least). Mean global LV MFR was 2.43 ± 0.87 and 2.33 ± 0.89, respectively, for NAC and AC measurements. Using a threshold of 2, 86 patients (83%) remained classified as normal and abnormal regarding global LV MFR whether AC was applied or not. Mean difference between NAC and AC values for the 18 other patients was 0.3.

CONCLUSION

AC correction does not significantly affect MFR measurement both in regional and global LV analyses.