Phantom Study of In-Stent Restenosis at High-Spatial-Resolution CT

Abstract

Purpose To examine the diagnostic performance of high-spatial-resolution (HSR) CT with 0.25-mm section thickness for evaluating renal artery in-stent restenosis. Materials and Methods A 0.05-mm wire phantom and vessel phantoms with renal stents with in-stent stenotic sections of varying diameters were scanned with both an HSR CT scanner equipped with 160-section multi-detector rows (0.25-mm section thickness) and a conventional CT scanner. The wire phantom was used to analyze modulation transfer function (MTF). With the vessel phantoms, the error rates were calculated as the absolute difference between the measured diameters and true diameters divided by the true diameters at the narrowing sections. For qualitative evaluation, overall image quality and diagnostic accuracy for evaluating stenosis in three stages were assessed by two radiologists. Statistical analyses included the paired t test, Wilcoxon signed-rank test, and McNemar test. Results HSR CT achieved 24.3 line pairs per centimeter ± 0.5 (standard deviation) and 29.1 line pairs per centimeter ± 0.4 at 10% and 2% MTF, respectively; and conventional CT was 12.5 line pairs per centimeter ± 0.1 and 14.3 line pairs per centimeter ± 0.1 at 10% and 2% MTF, respectively. The mean error rate of the measured diameter at HSR CT (8.0% ± 5.8) was significantly lower than that at at conventional CT (16.9% ± 9.3; P < .001). Image quality at HSR CT was significantly better than that at conventional CT (P < .001), but HSR CT was not significantly superior to conventional CT in terms of diagnostic accuracy. Conclusion Compared with conventional CT, high-spatial-resolution CT achieved spatial resolutions of up to 29 line pairs per centimeter at 2% modulation transfer function and yielded improved measurement accuracy for the evaluation of in-stent restenosis in a phantom study of renal artery stents. Published under a CC BY 4.0 license.

Physical evaluation of an ultra-high-resolution CT scanner

“…[1], new electronic designs with lower noise [2] and, more recently, smaller detector elements [3]. The ability to visualise anatomy and pathology in greater detail has the potential to benefit the imaging of the lung, temporal bone, vasculature and stent structure, as well as visualisation of small tumours and structures [3][4][5][6]. Ultra-high spatial resolution capabilities may also lead to a reduction in artefacts such as blooming, as well as an increased ability to quantify features of anatomical and pathological structures.…”

Technical Note: Performance comparison of ultra‐high‐resolution scan modes of two clinical computed tomography systems

“…(a) and (c)]. According to a previous report using Detector‐UHR, the aperture ratio of the Aquilion Precision is almost equivalent to that of conventional CT, which is achieved by reduction of the detector septa; thus the notable SPF difference was considered to be because of the relationship between the detector‐row width and z‐directional focal spot size and possibly by inherent detector sensitivity.…”

“…This UHR scan mode was reported to offer excellent diagnostic image quality of the middle and inner ear . However, its spatial resolution performance quantified by the modulation transfer function (MTF) has not been reported, whereas that of the Aquilion Precision has been reported …”

“…A phantom study reported that this system could measure instent restenosis at about half the error compared to a conventional CT system. 5 On the other hand, a dual source CT (DSCT) scanner (Somatom Force, Siemens Healthineers) provides a UHR scan mode that achieves UHR scans using an attenuating comb filter, which can be arranged to partially cover the detector surface in advance of scanning. The comb filter improves the spatial resolution by reducing each detector cell's aperture width at the expense of dose efficiency.…”

“…6 However, its spatial resolution performance quantified by the modulation transfer function (MTF) has not been reported, whereas that of the Aquilion Precision has been reported. 5 Regarding CT images with spatial resolutions exceeding those of currently available multidetector CT (MDCT) systems, the trade-off between image noise and spatial resolution has to be carefully considered for the requirements of clinical applications. 7 Studies evaluating the diagnostic image qualities of UHR scans using a 0.25-mm detector and comb filter targeted high contrast objects of coronary stents and the inner ear, respectively, and thereby it is difficult to evaluate the trade-off relationship from the results.…”