CT Clinical Case Study CT Cardiac Coronary CTA Using SnapShot Pulse on Patient with 3 Coronary Stents

James Earls, M.D. Fairfax Radiological Consultants, PC. Fairfax, Virginia

Patient history

This 73-year-old has a long history of coronary artery disease. Seven years ago, after presenting with chest pain and having myocardial ischemia documented, he underwent coronary angiography and intervention. He had 2 RCA and one obtuse marginal stents placed. In the RCA a 3.0-mm x 8.0-mm Duet stent was placed in the distal RCA, and a 3.0-mm x 13.0-mm Duet stent was placed in the mid RCA. In the first obtuse marginal artery, a 2.5-mm x 23.0-mm Duet stent was also placed. He has done well with excellent exercise tolerance and had been asymptomatic since stent placement. A recent dual isotope myocardial perfusion exam showed possible inferior wall ischemia, so the patient was referred by his cardiologist for
a coronary CTA.

Patient physiological data
Average HR: 62 bpm
Height: 5' 5''
Weight: 133 lbs
BMI: 22.1

Acquisition protocol
Scanner: LightSpeed® VCT XT evaluation system
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: 350
Total X-ray exposure time: 0.8 second
Total scan time: 5 seconds
Total radiation dose: 0.86 mSv*†

Contrast injection parameters

• Contrast – 80 ml at 5.5 cc/second (15 second duration)
  0 second phase delay
• Saline – 50 ml at 5.5 cc/second (9 second duration)

Diagnosis
Clinical findings

The coronary CTA exam images helped the radiologist determine the following:

There were 3 intracoronary stents present. The position of these can be seen on the maximal intensity image (Figure 1).

There is a long stent present in the first obtuse marginal branch (Figure 2). This is consistent with the 2.5-mm x 23-mm Duet stent placed in 1999. The stent appears widely patent without evidence of restenosis. The remainder of the OMB1 and the left circumflex coronary artery were patent without stenoses.

The LAD and diagonals demonstrated mild nonobstructive atherosclerosis (Figure 3).

Two stents were depicted in the RCA (Figure 4). One was present in the mid vessel, the second was in the distal RCA at the origin of the PDA.

The stent in the mid vessel was consistent with the 3.0-mm x 13-mm Duet stent placed in 1999 (Figure 5). The stent appears widely patent without evidence of restenosis.The remainder of the proximal and mid RCA was patent without stenoses.

In the distal RCA the third stent was present; again it was consistent with the 3.0-mm x 8-mm Duet stent placed in
1999 (Figure 6). The stent appears widely patent without evidence of restenosis. The stent extended from the RCA
into the posterlateral branch, passing over the origin “jailing” the PDA. The PDA and PLB were both widely patent.

In conclusion, the patient has three widely patent intracoronary stents without evidence of restenosis. The remainder of his coronary arteries was also patent without obstructing atherosclerosis. The indeterminate myocardial perfusion
exam was therefore determined to be false positive.

Discussion

It is impressive that the LightSpeed VCT XT evaluation system is able to accurately image these stents and the remainder of the coronary tree with detailed accuracy. In this case, the high degree of confidence generated by review of these
images allowed the doctor to determine not to perform a follow-up angiogram.

The ability to accurately acquire a coronary angiogram and depict coronary stents in the range of 2.5 mm in diameter,
with a small effective dose is remarkable.

In the future, with the advent of LightSpeed VCT XT evaluation system with SnapShot Pulse, the referring cardiologist is considering performing CCTA every other year, alternating yearly with a nuclear myocardial perfusion exam.