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Coronary CT angiography using dual source CT Naofumi Matsunaga Department of Radiology, Yamaguchi University Graduate School of Medicine Talk outline • Temporal resolution is 83 msec of dual source CT Faster shutter chance •Introduction of newly developed Somatom Definition Flash DSCT Improvement of Temporal Resolution Dual Source CT needs only 90 deg. rotation Single Source CT 330 ms / 2 = 165 ms (FWHM) Page 3 Dual Source CT 330 ms / 4 = 83 ms (FWHM) Cardiac cycle 1) Isovolumetric ventricular contraction 3) Isovolumetric ventricular relaxation 2) Ejection Diastasis （0-300ms） （80-120ms） 4) Rapid filling 5) Atrial contraction Time resolution needed for 64MSCT Isovolumetric relaxation time and Diastasis ECG Isovolumetric relaxation time （80-120ms） Diastasis （0-300ms） outflow inflow In two phases, the heart is free-motion, Time resolution of dual source CT is 83 msec, and sufficient for data acqusition. Simply speaking, two phase of best shutter chance. Cardiac cycle During the isovolumetric relaxation phase, semilunar and AV valves sets of valves are closed .-------Æmotion free Cited from Human Physiology, Mosby 1993, p374, Isovolumic relaxation time(ＩＲＴ) and Diastasis evaluated by dual doppler echo Ａ A normal case Outflow HR＝60 bpm IRT＝90msec more than 83msec Diastasis＝300msec more than 83msec ＩＲＴ diastasis Inflow Ａ A normal case Ｅ Outflow Inflow ＩＲＴ diastasis HR＝80 bpm IRT＝100msec more than 83msec Diastasis＝0msec less than 83msec Courtesy of Dr Miura, Yamaguchi University Isovolumic relaxation time(ＩＲＴ) and Diastasis evaluated by dual doppler echo Ａ Ｅ A normal case HR＝60 bpm IRT＝90msec more than 83msec Diastasis＝300msec more than 83msec diastasis ＩＲＴ Ｅ ＩＲＴ Ａ diastasis A case of congestive heart failure HR＝60 bpm IRT＝110msec more than 83msec Diastasis＝0msec less than 83msec Courtesy of Dr Miura, Yamaguchi University Change of IRT and Diastasis by heart rate Time (msec) IRT Diastasis ＊：P<0.01 VS HR≦60 200 165 ＊ 100 ＊ 83 0 SSCT DSCT HR≦60 (N=７) 60＜HR≦65 （N=10） Courtesy of Dr Fujimura, Yamaguchi University 65＜HR≦75 （N=8） 75≦HR HR(/min) （N=7） RSNA 2008, Education Exhibit No β blocker in dual source CT １．No need to consideration of contraindication of β blocker. hypersensitivity to β blocker、diabetic ketoacidosis、metabolic acidosis、marked bradycardia、AV block、 SA block 、sick sinus syndrome、cardiogenic shock、pulmonary hypertension、congestive heart failure、severe peripheral vascular disease、hypotension、 bronchial asthma、pheochromocytoma ２．No waiting time after administration of β blocker # Ｕｓｅ ｏｆ β blocker is stressful for the radiologist and cardiologist in the CT room. Diagnostic accuracy according to heart rate Brodoefel H, et al: Radiology 247;346-355 Good image quality without use of β blocker even if the heart rate is 97bpm RCA LAD LCX SOMATOM Definition Flash Flash speed. Lowest dose. SOMATOM Definition Flash Flash speed. Lowest dose. Dual Source CT on Next Stage Dual Source CT Cardiac Imaging ¾ 83msec Temporal Resolution ¾ no β-blocker ¾ Low Dose Dual Energy Imaging SOMATOM Definition Flash Flash speed. Lowest dose. Specifications X-Ray Tube Power Detector Gantry Rotation Temporal Resolution Spatial Resolution FOV (A /B system) Straton x 2 100kw x 2 128 slice x 2 0.28Sec/rot. 75ms 0.33mm 500/330mm 78cm 780 mm gantry aperture 2000 mm scan range 200cm S can Range SOMATOM Definition Flash Flash speed. Lowest dose. Single source CT Result: Single Single sourcesource CT @ high CT isscan limited to slow speed pitch would andcause slow scan acquisition speed gaps DSCT Flash Spiral High-Pitch Double Spiral Solution: Flash spiral enables pitch 3.2 for fastest speed of 43 cm/sec without any gaps SOMATOM Definition Flash Flash speed. Lowest dose. Conventional Technology Thorax: 5 s, breath hold Triple rule-out: 20 s, 20 mSv Pediatric: > 4s, sedation Whole body: > 10 s DSCT Flash Spiral Thorax: 0.6 s, no breath hold Triple rule-out: 0.6 s, < 5 mSv Pediatric: < 1s, no sedation Whole body: 4 s SOMATOM Definition Flash Flash speed. Lowest dose. Conventional Technology Scan Thorax: 5 s, breath hold Triple rule-out: 20 s, 20 mSv Pediatric: > 4s, sedation Whole body: > 10 s 4D dynamic scans: 16 cm DSCT Flash Spiral Scan Thorax: 0.6 s, no breath hold Triple rule-out: 0.6 s, < 5 mSv Pediatric: < 1s, no sedation Whole body: 4 s 4D dynamic scans: 48 cm SOMATOM Definition Flash Sub-mSv heart DSCT Cardio Flash Spiral Conventional CTA 135-175 ms temporal resolution 5-10 s scan time Slow pitch for overlapping acquisition Segment Reconstruction 8-40 mSv dose High-Pitch Double Spiral 75 ms temporal resolution 250 ms scan time (quarter beat) Breath hold optional Down to < 1 mSv dose SOMATOM Definition Flash Flash speed. Lowest dose. Headline SOMATOM Definition Flash Flash speed. Lowest dose. HR independent temp res. 75 ms Coll. 128 x 0.6 mm Spatial res. 0.33 mm 250 ms for 110 mm Rotation 0.25 s 100 kV, 320 mAs / rotation 0.8 mSv 0.25s for 110 mm 0.8mSv Courtesy of Friedrich-Alexander University Erlangen-Nuermberg - Institute of Medical Physics / Erlangen, Germany SOMATOM Definition Flash ImageSpiral Cardio Flash SOMATOM Definition Flash Flash speed. Lowest dose. HR independent temp res. 75 ms Coll. 128 x 0.6 mm Spatial res. 0.33 mm 280 ms for 120 mm Rotation 0.28 s 100 kV, 320 mAs / rotation 0.95mSv 0.28s for 120 mm 0.95mSv Courtesy of Friedrich-Alexander University Erlangen-Nuermberg - Institute of Medical Physics / Erlangen, Germany SOMATOM Definition Flash Low Dose Triple Rule-Out Headline SOMATOM Definition Flash Flash speed. Lowest dose. HR independent temp res. 75 ms Coll. 128 x 0.6 mm Spatial res. 0.33 mm 670 ms for 290 mm Rotation 0.28 s 100 kV 97 kg, BMI 29.9 1.6mSv 0.67s for 290 mm 1.6mSv Courtesy of Friedrich-Alexander University Erlangen-Nuermberg - Institute of Medical Physics / Erlangen, Germany SOMATOM Definition Flash Flash speed. Lowest dose. Courtesy of Friedrich-Alexander University Erlangen-Nuermberg - Institute of Medical Physics / Erlangen, Germany Summary • Temporal resolution of DSCT is 83msec. • Isometric relaxation time is always constant,irrespective of heart rate or decreased cardiac function, • In this period, the heart is stopped, and 83msec is always sufficient for the best chance for reconstruction. • Therefore, dual source CT is widely available in the patients from high to low heart rate without premedication of βblocker. Summary • Recently, innovative dual source scanner (FLASH) is developed; fast scan time less than 1 second, double spiral scan. • However, improvement of spatial resolution is expected for more detailed evaluation. Acknowledgement • With the courtesy of Siemens In Corporation. • Thank you for your attention.
