Photon-counting detector CT angiography to evaluate carotid and subclavian artery stents and compared to ultrasound and angiography - an in-vivo study with spectral reconstructions

Abstract

PurposeTo evaluate the potential of Photon-Counting Detector CT Angiography (PCD-CTA) for the assessment of carotid and subclavian artery stents compared to digital subtraction angiography (DSA) and Duplex ultrasound (DUS).MethodsThis study is a single-center, retrospective analysis of consecutive patients treated with a stent for high grade stenosis of the extra-cranial carotid and the subclavian artery between April 2023 and May 2024. Polyenergetic images (PE), iodine and virtual monoenergetic images were performed at different keV levels (40 and 80) and with two body vascular reconstruction kernels (Bv56 and 72) with and without iterative metal artifact reduction. Three independent readers assessed image quality using a 5-point Likert scale and region of interest analysis. A blinded, independent reading was performed to determine in-stent vessel stenosis.ResultsA total of 19 patients (64.3 ± 10.3 (mean patient age in years ± SD); 9 women) with carotid or subclavian artery stents and available DSA, DUS and PCD-CTA were analyzed. Virtual monoenergetic images (VMI) reconstructed with Bv56 at 40 keV, PE and IOD reconstructed with Bv56 scored higher and achieved higher SNRs and CNRs in the in-stent vessel lumen compared with Bv72 reconstructions (p < 0.001). In 2/19 cases with elevated flow velocities (>250 cm/s) in the in-stent vessel lumen, the subsequently performed PCD-CTA and DSA could rule out a high-grade stenosis.ConclusionPCD-CTA with spectral reconstructions allows a reliable non-invasive assessment of the in-stent vessel lumen in patients after carotid artery or subclavian artery stenting.

Keywords: CT-angiography; DSA; duplex sonography; photon counting CT; stent.

Figure 1.

Illustration of reconstruction protocol for polyenergetic (PE) and iodine (IOD) reconstructions with two different kernels. In the first row PE and in the second row IOD are listed and in the three columns, from left to right Bv56 kernel without iMAR, Bv56 with iMAR and Bv72. In detail: a = Bv56, PE; b = Bv56 with iMAR, PE; c = Bv72, PE; d = Bv56, IOD; e = Bv56 with iMAR, IOD; f = Bv72, IOD. Abbreviations: Bv: Body vascular kernel, iMAR: iterative metal artifact reduction.

Figure 2.

Illustration of reconstruction protocol for polyenergetic (PE) and iodine (IOD) reconstructions with two different kernels. In the first row PE and in the second row IOD are listed and in the three columns, from left to right Bv56 kernel without iMAR, Bv56 with iMAR and Bv72. In detail: a = Bv56, PE; b = Bv56 with iMAR, PE; c = Bv72, PE; d = Bv56, IOD; e = Bv56 with iMAR, IOD; f = Bv72, IOD. Abbreviations: Bv: Body vascular kernel, iMAR: iterative metal artifact reduction.

Figure 3.

Postinterventional PCD-CTA with VMI and iodine reconstructions of an in-stent stenosis treated with a second carotid stent in a patient with calcified plaques at the carotid bifurcation. The patient has two carotid WallStents^® (double layer) in the right carotid artery. A is an iodine reconstruction with Bv56; B is an VMI with Bv56 at 40 keV with Bv56 of the right carotid artery; C is a p.a. 2D projections of the right carotid artery. Abbreviations: Bv: Body vascular kernel, keV: kiloelectron-volt, PCD-CTA: Photon-counting detector CT-Angiography, VMI: Virtual Monoenergetic Imaging.