Usefulness of the virtual monochromatic image in dual-energy spectral CT for decreasing renal cyst pseudoenhancement: a phantom study.
AJR Am J Roentgenol 2013;
199:1316-9. [PMID:
23169724 DOI:
10.2214/ajr.12.8660]
[Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE
The purpose of this study was to determine the effect that dual-energy spectral CT has on renal cyst pseudoenhancement with a renal cyst phantom.
MATERIALS AND METHODS
Two renal compartments within a CT phantom were filled with 40- and 240-HU solutions of diluted contrast material, mimicking the nonenhanced phase and nephrographic phase of MDCT, respectively. A saline-filled tapering cylindric cyst model was used, simulating cysts of varying diameters (range, 0.7-3.0 cm) suspended in the renal compartments. The phantom was scanned using dual-energy CT (DECT) (80 and 140 kVp) and conventional, single-energy CT (120 kVp) with the same 64-MDCT scanner. Attenuation increase was measured for a cyst model within 40- and 240-HU dilutions. We compared the attenuation increase obtained on virtual monochromatic images from DECT with conventional, single-energy MDCT images using a paired Student t test.
RESULTS
Pseudoenhancement occurred in the conventional single-energy CT acquisitions, with water attenuation increase of 42.44 ± 4.03 HU measured at 120 kVp. In virtual monochromatic images of DECT, we observed less pseudoenhancement with water attenuation increase of 21.51 ± 6.18 HU at 70 keV. Both acquisitions yielded a p value less than 0.0001.
CONCLUSION
We achieved less pseudoenhancement of renal cysts with virtual monochromatic images of DECT compared with conventional single-energy CT. This method may be useful when an accurate differentiation between small renal cysts and solid masses is critical.
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