|
Coronary CTA Using SnapShot Pulse to Evaluate Etiology of Chest Pain
James Earls, M.D.
Fairfax Radiological Consultants, PC.
Fairfax, Virginia
|
|
Patient history
|
Clinical findings
A 65-year-old female patient came in for a work up due to
complaints of atypical chest pain which radiated to her back.
Although she had numerous cardiac risk factors, she had no
previous cardiac history. This patient is obese with a
BMI > 37. Body mass index (BMI) is a measure of body fat
based on height and weight that applies to both adult men
and women.
|
BMI categories
-
Underweight: <18.5
-
Normal weight: 18.5-24.9
-
Overweight: 25-29.9
-
Obesity: BMI ³ 30
|
|
The patient’s cardiac risk factors include a history of high cholesterol,
positive family history, hypertension and insulin-dependent diabetes.
Her calcium score of 101 is broken down as follows:
-
Left main: 0
-
Left anterior descending: 85
-
Left circumflex: 0
-
Right coronary: 16
-
Posterior descending: 0
-
Total calcium score: 101
-
Age/sex matching score percentile: 80
|
|
Patient physiological data
-
Average HR: 45 bpm
-
Height: 5' 5''
-
Weight: 225 lbs
-
BMI 37.4
|
|
Acquisition protocol
-
Scanner: LightSpeed® VCT XT
-
Scan type: Cardiac SnapShot™ Pulse
-
Rotation speed: 0.35 second
-
Detector configuration: 64 x 0.625 mm
-
Slice thickness: 0.625 mm
-
kVp: 120
-
mA: 750
-
Total X-ray exposure time: 1.0 second
-
Total scan time: 5 seconds
-
Total radiation dose: 2.33 mSv*
|
Contrast injection parameters
Visipaque™ contrast injection parameters:
-
Timing dose: 20 cc at 5.5 cc/second followed by 50 cc saline at 5.5 cc/second
-
Diagnostic dose: 80 cc at 5.5 cc/second followed by 50 cc saline
at 5.5 cc/second
|
Diagnosis
|
Clinical findings
The left main coronary artery is patent with evidence of
mild atherosclerosis (Figure 1).
The left anterior descending (LAD) and diagonals are
patent although there is evidence of mild nonobstructing
atherosclerosis (Figure 1).
The left circumflex coronary artery (LCx) and marginal
branches are patent. Again, there is evidence of mild
nonobstructing atherosclerosis.
The right coronary artery (RCA) is a very prominent vessel
(Figure 2, a and b). It has a maximum diameter of 7.0 mm
proximally (b). This is seen over the proximal several centimeters
of the vessel. Several small plaques are identified throughout
the nonobstructed vessel.
The posterior descending artery (PDA) arises from the right
coronary artery. The vessel is patent without obstruction
(Figure 3).
Based on the findings, the patient has mild atherosclerosis
seen in her LAD, LCx and RCA. She has a very prominent
proximal right coronary artery with a widely patent PDA.
The atherosclerosis, while being mild in nature, will warrant
observation in the coming years for further progression.
|
Discussion
|
The benefits of SnapShot Pulse on the LightSpeed VCT XT are
demonstrated with this large BMI study. We are now able to
provide diagnostic quality coronary CT images with
substantially reduced radiation exposure to the patient as
compared to helical techniques.
Currently in clinical practice, patients with known coronary
artery disease are frequently followed with serial nuclear
myocardial perfusion imaging (MPI) studies. These can have
radiation doses to the patient that, in the case of thallium
MPI studies, approach 50 mSv per study. In addition, women
and obese patients have a higher incidence of false-positive
MPI studies due to breast or diaphragmatic attenuation,
often obligating that a diagnostic invasive coronary
catheterization be performed.
This new low-dose coronary CTA technique provides the
clinician with new possibilities for following a patient’s
disease process because of the lower dose exposure.
* Obtained by EUR-16262 EN using chest factor of 0.017*DLP
|
|
|
