In 124 patients with CCTA and invasive coronary angiography (ICA) within 30 days, diagnostic performance of PCCT CCTA was similar with and without sublingual nitroglycerin. Per-patient sensitivity was 90.3% vs 90.9%, and NPV was 86.4% vs 88.9%, with no significant differences between groups.
The non-nitroglycerin group was numerically better for several diagnostic metrics—specificity 80.0% vs 63.3%, PPV 83.3% vs 71.8%, and accuracy 85.7% vs 77.0%—although none reached statistical significance. Likewise, no significant differences were found across LAD, LCx, or RCA analyses, so the findings remain hypothesis-generating rather than practice-changing.
Nitroglycerin increased left-main attenuation (634 ± 169 vs 546 ± 147 HU, p = 0.029) but did not improve SNR or CNR. The authors also raise the possibility that vasodilation of healthy reference segments may exaggerate percentage stenosis relative to diseased segments, potentially contributing to false-positive CCTA findings.
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Figure 3. Representative case demonstrating potential nitroglycerin-related overestimation of coronary stenosis severity. A 73-year-old man presenting with chest pain underwent photon-counting CCTA following administration of 0.4 mg sublingual nitroglycerin. (A) Curved multiplanar reformatted CCTA image demonstrates a proximal coronary artery diameter of 3.5 mm, a stenotic segment diameter of 1.8 mm, and a distal reference diameter of 3.0 mm. Based on CCTA findings, the lesion was classified as moderate stenosis (CAD-RADS 3, obstructive disease). (B) Invasive coronary angiography demonstrated slightly smaller reference vessel diameters and a slightly larger residual lumen at the stenotic segment, with measurements of 3.3 mm proximally, 1.9 mm at the stenosis, and 2.7 mm distally. Consequently, the lesion was classified as mild stenosis (non-obstructive disease) by invasive coronary angiography. The discrepancy is likely attributable to nitroglycerin-induced vasodilation of adjacent healthy coronary segments, resulting in approximately 10% enlargement of the reference vessel diameter without substantial dilation of the diseased segment. This differential vasodilatory response increases the apparent percentage stenosis on CCTA and may contribute to overestimation of stenosis severity.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Scan area | Coronary arteries / CCTA |
Acquisition mode | PCCT CCTA |
Tube voltage [kV] | 120 |
IQ level | 64 |
Dose modulation | Automated tube current modulation |
Rotation time [s] | 0.25 |
Detector slice collimation | 120 × 0.4 mm |
Prospective ECG acquisition | HR <75 bpm with regular rhythm; acquisition window centered at 60–80% of RR |
Retrospective ECG acquisition | HR >75 bpm or irregular rhythm; full radiation at 30–50% of RR, reduced to 10% during remainder |
Reconstruction slice thickness [mm] | 0.4 |
Reconstruction increment [mm] | 0.3 |
Matrix | 512 × 512 |
FOV | Dedicated cardiac FOV optimized for coronary assessment |
Kernel | Bv44 smooth and Bv60 sharp |
Iterative reconstruction | QIR 3 |
Contrast | Iohexol, Omnipaque 350 |
Contrast volume | BMI <25: 50–60 mL; BMI 25–30: 60–70 mL; BMI >30: 70–80 mL |
Injection rate | 5 mL/s |
Bolus triggering | Descending aorta; monitoring begins 8 s after injection onset; 100-HU threshold |
Post-trigger delay | 6 s |
Mixed bolus | 30 mL of 50% contrast/saline at 5 mL/s |
Saline chaser | 30 mL at 5 mL/s |
Venous access | 18-gauge IV |
Heart-rate control | IV metoprolol 5-mg increments every 5 min, maximum 25 mg; target HR <75 bpm |
Nitroglycerin comparison | 0.4 mg sublingual nitroglycerin vs no nitroglycerin |
Key Results
Parameter | Main finding |
|---|
Study population | 124 patients: 61 nitroglycerin / 63 no nitroglycerin |
Sensitivity | 90.3% vs 90.9%, p = 0.940 |
Specificity | 63.3% vs 80.0%, p = 0.160 |
PPV / NPV | 71.8% / 86.4% vs 83.3% / 88.9% |
Overall accuracy | 77.0% vs 85.7%, p = 0.220 |
Objective image quality | LM attenuation higher with nitroglycerin (634 vs 546 HU, p = 0.029), but SNR and CNR unchanged |
Source:
Kabakus IM, Maisuria DM, Chamberlin JH, Mencken IL, Lopez Rodriguez CG, Sagatelian MM, Burt JR, Baruah D. Is nitroglycerin still necessary for coronary CT angiography in the era of photon-counting CT? Journal of Cardiovascular Computed Tomography. 2026. In Press, Corrected Proof. Available online August 22, 2026. doi:10.1016/j.jcct.2026.08.007.
