A 76-year-old male patient was admitted to the hospital with an initial diagnosis of arrhythmia (atrial fibrillation and ventricular extrasystoles) and heart failure. He had been suffering from exertional dyspnea for the past year. This improved after rest but had aggravated over the past 4 days. A coronary CT angiography (cCTA) was requested for further evaluation.
cCTA images showed a right coronary artery (RCA) dominant system. Multiple calcified and non-calcified plaques were visualized in all coronary arteries (Figs. 1 and 3), causing severe stenoses in the proximal, middle and distal RCA, moderate to severe stenoses in the proximal left anterior descending artery (LAD), as well as mild stenoses in the left main artery (LM) and the circumflex artery (Cx). Both atria were significantly enlarged (Fig. 2).
Fig. 1:Curved MPR images show multiple calcified and non-calcified plaques in all coronary arteries, causing severe stenoses in the proximal, middle and distal RCA (Fig. 1a), moderate to severe stenoses in the proximal LAD (Fig. 1b) and mild stenoses in the LM and Cx (Fig. 1c).
Fig. 2:An axial image shows significantly enlarged atria.
Fig. 3:VRT images of the coronary tree show multiple calcified plaques in all coronary arteries in three dimensions.
cCTA is an established non-invasive and robust imaging assessment for coronary arteries. To achieve optimal image quality, appropriate scanning techniques need to be selected dependent upon the patient’s situation. In this case, the patient could not maintain a standard breath-hold command due to his dyspnea. The case was further complicated by the diagnosed heart failure and a highly arrhythmic heart rate (atrial fibrillation and ventricular extrasystoles). In such a critical situation, a so-called “Double Turbo Flash Spiral” scan mode – two consecutive spiral scans, prospectively ECG-triggered, using a high pitch of 3.2 (table movement speed of 736 mm/s) is performed. Each scan acquires images of the entire heart within one cardiac cycle, using a single bolus of intravenous contrast agent, and free breathing technique. Even though both scans are triggered in non-optimal cardiac phases (Fig. 4) due to the arrhythmia – the first was too late (80% to 1%), and the second was too early (23% to 42%) – both acquisitions yielded amazing image quality. It is reasonable to assume that this is due to the combination of a 66ms high temporal resolution Dual Source imaging and the less-prominent motion of the atria and the ventricles due to heart failure.
Alternatively, a prospectively ECG-triggered sequential scan mode with absolute delay could have been considered, however, artifacts due to the patient’s free breathing, would have probably occurred at the sequence stack transition images. It is also noteworthy that the trigger level is changed from 100 HU to 120 HU, since a prolonged time-to-peak due to heart failure is anticipated. The contrast injection rate was also reduced from 4.5 mL/s to 3.6 mL/s to achieve an extended plateau of the time-to-density curve, ensuring an optimal contrast enhancement for the second scan. This case demonstrates that optimal image quality for coronary assessment can be achieved, even under difficult circumstances, when the appropriate scan techniques are selected and applied.
Fig. 4:ECG recorded during the first (Fig. 4a) and second (Fig. 4b) scans show that both acquisitions were triggered in nonoptimal cardiac phases.
Double Turbo Flash Spiral
134.5 / 134.5 mm
Caudo-cranial / Cranio-caudal
0.18 / 0.18 s
90 / 80 kV
491 / 484 mAs
3.47 / 3.23 mGy
60.8 / 38.9 mGy cm
0.25 / 0.25 s
3.2 / 3.2
192 x 0.6 mm / 192 x 0.6 mm
0.75 / 0.75 mm
0.5 / 0.5 mm
Bv40 / Bv40
43-86 / 43-72 bpm
45 + 35 mL saline
Bolus tracking in the descending aorta at 120 HU with an additional 5s for the first scan / +6.2s after the first scan