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1. PUSHPAGIRI
CARDIOLOGY
14-03-2022
Basics of
Cardiac CT

2. GODFREY HOUNSFIELD
Father of CT Scan

3. CT Machine

4. 1. Gantry
2. Table
3. Console

6. • 1st generation- 4.5 min/image
• series of exposures - X-ray source moved laterally
• tube then rotated to a different position - sequence repeated
• 2nd generation - 2.5 min/image
• fan beam architecture – activate multiple detectors before moving to a new
position
• 3rd generation - 18 s/image
• rotating X-ray source coupled to rotating detectors
• 4th generation - 2 s/image
• rotating X-ray source with a fixed detector array

7. • EDCT
• MDCT (new)

8. • Sequential mode – Prospective Gating
• Helical mode – Retrospective Gating (Spiral)

10. The Detecter

11. Data Acquisition System (DAS)

12. The Console

15. Four slice at a time

16. Detecter configuration

19. Temporal Resolution

20. Table Feed

21. Spacial Resolution

22. ECG Gating

23. Best position – at Mid Diastole – less movement
HR < 65 / mt

24. Radiation is kept maximum at MID DIASTOLE only

25. Prostective ECG triggered axial
Scanning is initiated at a pre-defined time after the peak of R wave

26. One block per heart beat

27. Padding Data
• To compensate for error with moving heart rate

28. Applications in Cardiology

29. • Determine Atherosclerosis – by Coronary Calcium Scoring
• CT-CAG

31. Understanding the imaging planes

32. Volume rendered Image

41. CORONARIES

55. VALVES

64. LFET VENTRICLE

72. CORONARY PLAQUE
Calcium Scoring

73. • Coronary calcium is defined as a lesion above a threshold of 130 HU,
with an area of ≥3 adjacent pixels (at least 1mm2)

75. • CT-CAG
• Both Lumen and Vessel
• CAG
• Only Lumen

76. No Calcium

77. Has Calcium

88. Realtime Calcium Color coding
LAD – Orange
RCA - Green

89. CT CAG

90. • Lower Heart Rate
• Beta Blocker IV
• Dilate Coronaries
• Sub lingual nitrates
• Breath Hold
• 6-20 seconds
• Contrast
• 50-120 ml
• Radiation
• 3 – 15 mSv

91. Identifying the Vessels on CT-CAG

93. Curved Multiplanar Rendered Image

94. Ribbon
View

96. Straightened Multiplanar Rendered Image

97. PLAQUE MORPHOLOGY

102. IDENTIFYING HIGH RISK PLAQUE

103. We do not know the wall
and plaque characteristics

105. • Lumen
• Wall
• Composition of Wall

117. STENT PATENCY

118. • Metallic Stents – causes blooming artefacts
• Third generation stents – less artefacts
• Can be imaged

121. CT in Post CABG

123. CT in CTO Lesions

125. CT in Post MI

127. Other uses
• CT in EVEMF
• CT in Pericardial Diseases
• CT in PE (Triple Rule out)
• CT in TAVR

128. LIMITATIONS OF CT

129. • Does not have the same spatial or temporal resolution as CAG
• cannot be performed in all pts (e.g.arrhythmias)
• Purely diagnostic -doesn’t provide option for immediate intervention
• If the predicted necessity for an intervention is reasonably high, the
patient should proceed directly to CAG
• Obesity
• Small vessels, Collaterals, <1.5mm)

130. CT-CAG vs CAG

131. Cardiac CT – Gatekeeper to cathlab

132. THANK YOU