Myocardial CT perfusion imaging for the detection of obstructive coronary artery disease: multisegment reconstruction does not improve diagnostic performance

Abstract

Background: Multisegment reconstruction (MSR) was introduced to shorten the temporal reconstruction window of computed tomography (CT) and thereby reduce motion artefacts. We investigated whether MSR of myocardial CT perfusion (CTP) can improve diagnostic performance in detecting obstructive coronary artery disease (CAD) compared with halfscan reconstruction (HSR).

Methods: A total of 134 patients (median age 65.7 years) with clinical indication for invasive coronary angiography and without cardiac surgery prospectively underwent static CTP. In 93 patients with multisegment acquisition, we retrospectively performed both MSR and HSR and searched both reconstructions for perfusion defects. Subgroups with known (n = 68) or suspected CAD (n = 25) and high heart rate (n = 30) were analysed. The area under the curve (AUC) was compared applying DeLong approach using ≥ 50% stenosis on invasive coronary angiography as reference standard.

Results: Per-patient analysis revealed the overall AUC of MSR (0.65 [95% confidence interval 0.53, 0.78]) to be inferior to that of HSR (0.79 [0.69, 0.88]; p = 0.011). AUCs of MSR and HSR were similar in all subgroups analysed (known CAD 0.62 [0.45, 0.79] versus 0.72 [0.57, 0.86]; p = 0.157; suspected CAD 0.80 [0.63, 0.97] versus 0.89 [0.77, 1.00]; p = 0.243; high heart rate 0.46 [0.19, 0.73] versus 0.55 [0.33, 0.77]; p = 0.389). Median stress radiation dose was higher for MSR than for HSR (6.67 mSv versus 3.64 mSv, p < 0.001).

Conclusions: MSR did not improve diagnostic performance of myocardial CTP imaging while increasing radiation dose compared with HSR.

Trial registration: CORE320: clinicaltrials.gov NCT00934037, CARS-320: NCT00967876.

Keywords: Coronary angiography; Coronary artery disease; Multidetector computed tomography; Myocardial perfusion imaging; Sensitivity and specificity.

Fig. 1

Flow chart showing the patient selection strategy for comparison of diagnostic performance and radiation dose of MSR and HSR of myocardial CTP imaging datasets in patients with suspected or known CAD. The study population for intraindividual comparison of diagnostic performance consisted of 93 of 134 patients with multisegment acquisition of stress CTP allowing both HSR and MSR. The remaining 41 of 134 patients had predefined single-segment acquisition due to heart rates < 65 bpm, and only HSR was possible. These patients served as a control group for interindividual radiation dose comparison. bpm Beats per minute, CAD Coronary artery disease, CTP Computed tomography perfusion, HSR Halfscan reconstruction, MSR Multisegment reconstruction

Fig. 2

Technical background for generating temporal reconstruction windows of MSR and HSR (a) and their dependency on patient’s heart rate (b). a The minimum partial scan raw data needed to reconstruct a volume require half a gantry rotation (+ fan angle). HSR uses partial scan raw data acquired within one heart beat (illustrated on the left in light grey) and consequently generates a per-segment temporal reconstruction window of half a gantry rotation. MSR uses partial scan raw data of approximately half a gantry rotation acquired in at least two successive heart beats, illustrated on the right for two segments in dark grey (segment one) and black (successive segment two). The resulting minimum per-segment temporal reconstruction window of MSR can be calculated as follows: Temporal reconstruction window = gantry rotation time / (2 × number of acquired segments). Thereby, acquiring more segments improves the per (heart)-segment temporal reconstruction window of MSR compared with HSR by up to the same factor as the number of segments acquired [see references [–11]] at the cost of a higher radiation dose [see references [8, 12]]. b Line graphs showing the per-segment temporal reconstruction window of MSR and HSR depending on individual patient’s heart rate for a 350-ms gantry rotation time and acquisition of up to four segments. The temporal reconstruction window of HSR is always 175 ms, whereas the temporal reconstruction window of MSR ranges from 44 to 175 ms depending on heart rate. Data by courtesy of the equipment vendor. HSR Halfscan reconstruction, MSR Multisegment reconstruction

Fig. 3

HSR and two-segment MSR of stress myocardial CTP in a 55-year-old man with suspected coronary artery disease and typical angina pectoris in comparison with invasive coronary angiography. a HSR shows a moderate perfusion defect in the left anterior descending artery territory (arrow), which is also suggested by moderate hypoattenuation in the corresponding area (circle) of the polar myocardial attenuation map; CTP with HSR was considered positive. b MSR shows only very slightly reduced perfusion (arrowhead) and only weak hypoattenuation in the corresponding area (dotted circle) of the polar myocardial attenuation map; CTP with MSR was considered negative. c Invasive coronary angiography reveals visually high-grade diameter stenosis (*) of the left anterior descending artery with 61% stenosis in quantitative invasive coronary angiography (**), corresponding to a true-positive CTP with HSR (a) and a false-negative CTP with MSR (b). Contrast-enhanced CTP in mid-heart short-axis view with 8-mm slice thickness and rainbow-red colour preset using a predefined window level/window width of 200/400. CTP Computed tomography perfusion, HSR Halfscan reconstruction, MSR Multisegment reconstruction

Fig. 4

All patients: receiver operating characteristic areas under the curve for comparison of MSR and HSR of myocardial competed tomography perfusion in per-patient (a) and per-territory analysis (b) using 50% diameter stenosis detected on quantitative coronary angiography as a reference standard. In all 93 patients, the area under the curve of MSR was inferior to that of HSR for both levels of analysis (p < 0.001). HSR Halfscan reconstruction, MSR Multisegment reconstruction

Fig. 5

Boxplots showing estimated radiation dose in mSv of stress computed tomography perfusion in patients with multisegment acquisition, which allowed both MSR and HSR (93 patients), and in patients with HSR only (41 patients). Boundaries of boxes represent the lower and upper quartiles and horizontal lines in boxes the medians. Outliers are depicted as individual open circles. In the HSR-only group, MSR was not possible in 9 patients despite multisegment acquisition of two segments. Mean radiation dose of patients with both MSR and HSR was higher than that of patients with HSR (p < 0.001). HSR Halfscan reconstruction, MSR Multisegment reconstruction