The basics of cardiac CT imaging
Posted on by Marc N. Katz

Coronary CT for Cardiology Fellows

My notes on coronary computerized tomography (CT).

Anatomy

  • Coronary artery segmentation
    Coronary artery segmentation
  • Normal coronary course
    Normal coronary course
  • Normal anatomy on CT
    Normal anatomy on CT
  • Common anomalous coronary arteries
    Common anomalous coronary arteries
  • Common anomalous coronary arteries
    Common anomalous coronary arteries

Classification of anomalous coronary arteries

  1. Anomalies of:
    1. Origin (>LCX from right coronary sinus most common)
    2. Course
    3. Intrinsic anatomy
    4. Termination
  2. Hemodynamic consequence: non/significant
  3. Coronary fistula
  4. Complete myocardial bridging (>LAD most common)
  5. Association with higher risk of sudden cardiac death (SCD)

Normal Anatomy

  • A normal CTCA has a high negative predictive value (98– 100%) for excluding CAD
  • Indications for CTCA:
    • Low-to-intermediate risk patients with acute chest pain and non-diagnostic ECG and serum biomarkers
    • Low-to-intermediate probability of CAD and unable to exercise or with inconclusive functional test results

Malignant Anatomy: associated with chest pain, myocardial ischemia, or sudden cardiac death

  1. RCA arising from left sinus
  2. Left main coronary artery (LMCA) arising from right coronary sinus
  3. LMCA arising from the pulmonary artery

RCA arising from left side- generally better prognosis

  • Right coronary artery originating from the left coronary sinus. RCA in red, Left main coronary artery yellow. The proximal RCA's acute angle take off passes through the pulmonary trunk and aortic root causing moderate compression.
    Right coronary artery originating from the left coronary sinus. RCA in red, Left main coronary artery yellow. The proximal RCA’s acute angle take off passes through the pulmonary trunk and aortic root causing moderate compression.
  • Myocardial bridging of the mid LAD
    Myocardial bridging of the mid LAD
  • Pulmonary trunk level showing LMCA originating from pulmonary artery (red asterisk)
    Pulmonary trunk level showing LMCA originating from pulmonary artery (red asterisk)
  • Aorta gives rise to RCA. Pulmonary artery gives rise to LMCA, now dilated
    Aorta gives rise to RCA. Pulmonary artery gives rise to LMCA, now dilated
  • Again showing aorta gives rise to RCA. Pulmonary artery gives rise to LMCA, now dilated
    Again showing aorta gives rise to RCA. Pulmonary artery gives rise to LMCA, now dilated
  • Again showing aorta gives rise to RCA. Pulmonary artery gives rise to LMCA, now dilated
  • Anomalous left coronary from the pulmonary artery (ALPACA or Balnd-White-Garland syndrome)
    Anomalous left coronary from the pulmonary artery (ALPACA or Balnd-White-Garland syndrome). Poor prognosis. Infant type worse as no time for collaterals and die within first year of life without surgical intervention. Adults can develop robust collaterals with giant tortuous vessels

Ischemic Cardiomyopathy (ICM)

High risk calcification features associated with higher event rates:

  • Low attenuation plaque: <30 Hounsfield units
  • Positive remodeling: lesion with vessel area >10% larger than a proximal normal reference site (remodeling index >1.1)
  • Napkin-ring sign: low-attenuation core surrounded by a rim-like area of higher attenuation (but less than 130 HU)
  • Spotty calcification: <3 mm length calcifications comprising <90°
  • CTA plaque phenotype features
    CTA plaque phenotype features
  • CTA plaque phenotype features
    CTA plaque phenotype features
  • CAD-RADS scoring and modifiers
    CAD-RADS scoring and modifiers

Coronary artery calcium score (CACS) of 0

  • Asymptomatic, independent of Framingham risk score: very low risk of events (0.10% per year), safety window of at least 5 years
  • No benefit from aspirin for primary prevention
  • Patients with abnormal lipid profile but CACS 0 have little benefit from statin
  • Stable symptomatic patients with low-to-intermediate pretest likelihood of CAD, a CACS 0 can safely exclude flow-limiting coronary disease
  • CACS of 0
    CACS of 0
  • CACS of 0. Minimal calcium in the aortic root and aortic valve
    CACS of 0. Minimal calcium in the aortic root and aortic valve

Abnormal coronary artery calcium score (CACS)

  • Symptomatic patients with CACS> 400 are at high risk of events (>2% per year), independent of risk factors and functional tests.
  • CACS>1000, even if normal stress testing, have significantly higher risk of major adverse events
  • CACS 1832
    Extensive coronary calcifications (CACS 1832) in 97th age and sex matched percentile. Diffuse in D1 and dRCA, concentric in mRCA, and spotty at ostial LAD and LCX. Very high likelihood of CV events and high likelihood of obstructive CAD.
  • Bicuspid AV with aortic dilation, and non-obstructive mixed plaque with evidence of positive remodeling`
    Bicuspid AV with aortic dilation, and non-obstructive mixed plaque with evidence of positive remodeling
  • pLAD, mLAD, dLAD in cross section
    pLAD, mLAD, dLAD in cross section
  • Obstructive CAD in LAD
    Obstructive CAD in LAD

Coronary Dissection

  • Linear low-density intraluminal image suggestive of focal dissection
    Linear low-density intraluminal image suggestive of focal dissection
  • Moderate ostial RCA stenosis. PRedominantly non-calcified eccentric lesion with low-attenuation core
    Moderate ostial RCA stenosis. PRedominantly non-calcified eccentric lesion with low-attenuation core
  • Moderate ostial RCA stenosis. PRedominantly non-calcified eccentric lesion with low-attenuation core
    Moderate ostial RCA stenosis. PRedominantly non-calcified eccentric lesion with low-attenuation core

LAD calcification

  • Calcified LAD with severe dLAD lesion
    Calcified LAD with severe dLAD lesion
  • Severe focal, eccentric, predominantly non-calcified lesion in mid-to-distal LAD with low attenuation core, positive remodeling, and napkin ring sign
    Severe focal, eccentric, predominantly non-calcified lesion in mid-to-distal LAD with low attenuation core, positive remodeling, and napkin ring sign

CTO of LCX with RCA collaterals in patient with discordant normal SPECT but abnormal ECG stress (2mm ST-depressions) sent for CTCA to evaluate coronary anatomy

  • Diffuse calcification of D1 and CTO of LCX
    Diffuse calcification of D1 and CTO of LCX

Suggested Reading

  1. The Complete Guide to Cardiac CT
  2. Clinical Atlas of Cardiac and Aortic CT and MRI by Patricia M. Carrascosa, Carlos M. Capuñay, Alejandro Deviggiano, Gaston A. Rodriguez-Granillo