Assessment of In-Stent Restenosis Using Iodine Density Imaging With Spectral Cardiac Computed Tomography

A 47-year-old man presented with chest pain, but without obvious ST changes or T-wave flattening and serum myocardial enzymes were normal. Percutaneous coronary intervention for unstable angina 1 year earlier revealed 90% stenosis of the left anterior descending artery and a 2.25×24-mm Promus Premier (Boston Scientific, Natick, MA, USA) stent was implanted. At 6 months post-procedure, coronary angiography (CAG) was performed to assess chest pain, which revealed severe stenosis proximal to the stent. Another Promus Premier stent (2.5×16 mm) was implanted, overlapping the first stent. Subsequent cardiac computed tomography (CT) with spectral CT (IQon Spectral CT; 120 kV, 700 mAs, volume CT dose index: 63.4 mGy; Phillips Healthcare, Best, The Netherlands) was performed to determine the cause of the recurrent chest pain; however, assessment of the stent lumen was difficult (Figure A,B). Iodine density images showed thinly demarcated stent struts with in-stent restenosis (ISR) (Figure C,D). The guidelines state that it is reasonable to assess stents ≥3 mm in diameter with coronary CT angiography, but is not recommended for stents <3 mm in diameter because artifacts reduce the accuracy of the assessment.¹ Iodine density images are most commonly used to distinguish enhanced and non-enhanced lesions. In this case, an in-stent assessment of the 2.25-mm stent was possible. CAG, intravascular ultrasonography, and iodine densitometry findings (Figure E,F) were similar in this case of ISR.

Figure.

Curved planar reconstruction images: conventional (A) and cross-sectional (B). Spectral computed tomography (CT): curved planar reconstruction image (C) and cross-sectional iodine density image (D) showing shadowing on the stent in the left anterior descending artery (LAD), with severe stenosis (yellow arrow). Coronary angiography findings (E) were consistent with the CT findings (red arrow), leading to a diagnosis of in-stent restenosis by intravascular ultrasonography (F).

Acknowledgments / Conflict of Interest / Sources of Funding

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Reference

• 1.   Taylor AJ, Cerqueira M, Hodgson JMcB, Mark D, Min J, O’Gara P, et al. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 appropriate use criteria for cardiac computed tomography. J Am Coll Cardiol 2010; 56: 1864–1894, doi:10.1016/j.jacc.2010.07.005.