Coronary artery disease
Usefulness of 64-Slice Multidetector Computed Tomography for Detecting Drug Eluting In-Stent Restenosis

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The aim of this study was to evaluate the accuracy of a new-generation spiral multidetector computed tomographic scanner (the Brilliance 64) in the diagnosis of coronary in-stent restenosis (ISR). Forty-one patients with 87 coronary stents (70 drug-eluting stents) implanted were examined. Patients underwent multidetector computed tomography (MDCT) 6.7 ± 6.9 days before scheduled invasive coronary angiography, using intravenous contrast enhancement. Images were reconstructed in multiple formats using retrospective electrocardiographic gating. Stents were viewed in their long and short axes and were visually classified for the presence or absence of binary ISR (diameter reduction >50%), including the 5-mm borders proximal and distal to the stent. ISR was found by invasive coronary angiography in 13 of the stented segments (15%) and in 8 patients (19%). Of these, 11 cases of ISR were correctly detected by MDCT; additionally, 1 severely calcified stented segment was considered as occluded by MDCT (sensitivity 84%, 95% confidence interval [CI] 54% to 98%). Seventy-three of 74 stented segments without ISR were correctly classified by MDCT (specificity 97%, 95% CI 93% to 100%), whereas 2 stented segments were classified as false-negative ISR. The positive predictive value was 92% (95% CI 84% to 97%), the negative predictive value was 97% (95% CI 90% to 99%), and predictive accuracy was 96% (95% CI 90% to 99%). After the exclusion of the calcified stented segment, the sensitivity, specificity, positive predictive value, negative predictive value, and predictive accuracy were 84% (95% CI 74% to 91%), 100% (95% CI 96% to 100%), 100% (95% CI 96% to 100%), 97% (CI 90% to 99%), and 98% (95% CI 92% to 99%), respectively. In conclusion, even with improved scanner technology, the sensitivity for the detection of ISR was moderate (84%). Thus, further studies are needed to determine whether MDCT will be a clinically useful and cost-effective tool for the evaluation of ISR in the clinical arena.

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Methods

From November 2005 to August 2006, 57 consecutive patients with previous stent implantation who were scheduled for ICA were included in the study to compare multidetector computed tomography (MDCT) with the gold standard, ICA. We excluded patients with the following characteristics: previous allergic reaction to iodinated contrast agent, impaired renal function (serum creatinine >1.6 mg/dl), contraindication to β blockers (high-degree heart block, poor left ventricular function, asthma, or

Results

Two of the 45 patients selected for the study had technically inadequate scans: the first for scan failure, and the second for arrhythmia during the scan. Moreover, 1 patient was excluded from the study because of an allergic reaction to iodinated contrast agent after MDCT and another because of refused participation. The remaining 41 patients constituted the study population. The baseline clinical and angiographic characteristics of these patients are listed in Table 1, and the stent (n = 87)

Discussion

Although the reported accuracy for 16- and 64-slice MDCT in the assessment of stenoses in nonstented coronary arteries is high, the visualization of the lumen within coronary artery stents is more challenging, because the stents produce artifacts by increasing the strut thickness (partial volume artifacts) and thereby artificially reducing the intrastent lumen. Only a small number of studies, performed using 16-slice MDCT, have evaluated the value of MDCT to detect ISR.1, 2, 3, 4, 5 In these

Acknowledgment

We would like to acknowledge the expert assistance of Antonella Pastorini, anesthesiologist; Daniela Roberto, Lapo Caratelli, and Sergio Armeli, radiologist technicians; and Paola Baldini and Fabio Torrini, technicians, in the performance of this study.

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