Combined evaluation of myocardial perfusion and coronary morphology in the identification of subclinical CAD

Summary

Purpose: To evaluate the mean effective radiation dose of ¹³N-ammonia PET/CT and ECGpulsing CT angiography (CTA) in the evaluation of myocardial perfusion, myocardial blood flow (MBF) and coronary morphology for the identification of subclinical CAD. Patients, material, methods: Following rest-stress ¹³N-ammonia PET/CT perfusion imaging and MBF quantification, ECG-pulsing CTA at a pulse window of 70% of the R-R cycle was performed in ten healthy controls and in sixteen individuals with cardiovascular risk factors. Individual radiation dose exposure for ECG-pulsing CTA was estimated from the dose-length product. Results: PET demonstrated normal perfusion in all study individuals, while hyperemic MBFs during dipyridamole stimulation and the myocardial flow reserve (MFR) in cardiovascular risk individuals were significantly lower than in healthy controls (1.34 ± 0.26 vs. 2.28 ± 0.47 ml/g/min and 1.48 ± 0.39 vs. 3.24 ± 0.81, both p . 0.0001). Further, ECG-pulsing CTA identified mild calcified and non-calcified coronary plaque burden in 7 (43%) individuals of the cardiovascular risk group. Rest-stress ¹³N-ammonia PET/CT perfusion study yielded a mean effective radiation dose of 3.07 ± 0.06 mSv (2.07 ± 0.06 mSv from the rest-stress ¹³N-ammonia injections and 1.0 mSv from the 2 CT transmission scans), while ECG-pulsing CTA was associated with 5.57 ± 2.00 mSv. The mean effective radiation dose of the combined ¹³N-ammonia PET/CT and ECG-pulsing CTA exams in the evaluation of myocardial perfusion and coronary morphology was 8.0 ± 1.5 mSv. Conclusion: ¹³N-ammonia PET/CT and ECG-pulsing CTA affords cardiac hybrid imaging studies in the evaluation of subclinical CAD with a relatively low mean effective radiation exposure of 8.0 ± 1.5mSv.

Zusammenfassung

Ziel: Erfassung der mittleren effektiven Strahlendosis bei kombinierter Anwendung der kardialen ¹³N-Ammoniak PET/CT und EKG-getriggerten CTAngiographie (CTA) zur Bestimmung der myokardialen Perfusion, des myokardialen Blutflusses (MBF), und der koronaren Morphologie für die Identifizierung einer subklinischen koronarer Herzerkrankung (KHK). Patienten, Methoden: Bei 10 Gesunden (Kontrollen) und 16 Personen mit kardiovaskulären Risikofaktoren wurde im Anschluss einer Ruhe-Stress-¹³N-Ammoniak-PET/CT-Perfusions- und MBF-Untersuchung, eine EKG-getriggerte CTA mit einem Trigger-Fenster von 70% des R-R-Zyklus durchgeführt. Die individuelle Strahlendosis-Exposition für die EKGgetriggerte CTA wurde mittels Dosis-Längen- Produkt ermittelt. Ergebnisse: Die PET-Untersuchung ermittelte bei allen Personen eine normale myokardiale Perfusion, wohingegen der hyperämische MBF-Anstieg während Dipyridamol-Stimulation und die myokardiale Flussreserve (MFR) in der kardiovaskulären Risiko-Gruppe im Vergleich zu Kontrollen deutlich vermindert waren (1,34 ± 0,26 vs. 2,28 ± 0,47 ml/g/min und 1,48 ± 0,39 vs. 3,24 ± 0,81, beide p ≤ 0,0001). Des Weiteren wurden mittels EKG-getriggerte CTA kalzifizierte und nicht-kalzifizierte koronare Plaque-Bildung in 7 (43%) der kardiovaskulären Risko-Gruppe identifiziert. Die Ruhe-Stress- ¹³N-Ammoniak-PET/CT-Untersuchung ergab eine mittlere effektive Strahlendosis von 3,07 ± 0,06 mSv (2,07 ± 0,06 mSv von den Ruhe- Stress ¹³N-Ammoniak Injektionen und 1,0 mSv von den 2 CT Transmissions-Scans), während die EKG-getriggerte CTA mit eine Strahlenbelastung von 5,57 ± 2,00 mSv assoziiert war. Die kombinierte Anwendung einer kardialen ¹³N-Ammoniak- PET/CT und EKG-getriggerten CTA zur Bestimmung der myokardialen Perfusion und der koronaren Morphologie ergab schlussendlich eine mittlere effektive Strahlendosis von 8.0 ± 1.5 mSv. Schlussfolgerung: Die kombinierte Anwendung einer kardialen ¹³N-Ammoniak PET/CT und EKG-getriggerten CTA erlaubt kardiale Hybrid- Untersuchungen für die Identifizierung einer subklinischen KHK mit relativ geringer mittlerer effektiver Strahlenbelastung von 8.0 ± 1.5 mSv.

Keywords

Low dose - computed tomography coronary angiography - coronary circulation - feasibility - myocardial blood flow - retrospective gating - positron emission tomography

Schlüsselwörter

CT-Angiographie - Koronarkalk - Hybridbildgebung - Myokardperfusion - myokardiale Flussreserve - ¹³N-Ammoniak - PET-CT - Strahlenbelastung

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