PT  - JOURNAL ARTICLE
AU  - Hartman, J.B.
AU  - Moran, S.
AU  - Zhu, C.
AU  - Sharp, J.
AU  - Hippe, D.S.
AU  - Zamora, D.A.
AU  - Mossa-Basha, M.
TI  - Use of CTA Test Dose to Trigger a Low Cardiac Output Protocol Improves Acute Stroke CTP Data Analyzed with RAPID Software
AID  - 10.3174/ajnr.A7428
DP  - 2022 Mar 01
TA  - American Journal of Neuroradiology
PG  - 388--393
VI  - 43
IP  - 3
4099  - http://www.ajnr.org/content/43/3/388.short
4100  - http://www.ajnr.org/content/43/3/388.full
SO  - Am. J. Neuroradiol.2022 Mar 01; 43
AB  - BACKGROUND AND PURPOSE: Contrast curve truncation in CTP protocols may introduce errors. We sought to identify risk factors and design a protocol to avoid truncation while limiting radiation.MATERIALS AND METHODS: In an initial fixed-timing cohort, patients underwent a 65-second CTP with 2-second delay postcontrast injection. Multivariable analysis identified factors associated with truncation. A later case-specific cohort underwent either the original protocol or a low cardiac output protocol with a 7-second delay and 75-second scanning window, with selection determined by CTA test-dose enhancement upswing delay. Time-density curves were assessed for truncation and compared between the 2 groups, and the radiation dose was evaluated.RESULTS: From September 2017 through May 2018, one hundred fifty-three patients underwent the standard fixed-timing protocol. Age (OR, 1.82/10-year increase; P = .019), reduced left ventricle ejection fraction (OR, 9.23; P = .001), and hypertension (OR, 0.32; P = .06) were independently associated with truncation in an exploratory multivariable model. From May 2018 through April 2019, one hundred fifty-seven patients underwent either the standard (72 patients) or low cardiac output protocol (85 patients). The fixed-timing cohort had 15 truncations (9.8%) versus 4 in the case-specific cohort (2.5%; P = .009). If the low cardiac output protocol were applied to those with >10.6% predicted risk of truncation based on age, left ventricle ejection fraction, and hypertension, the number of truncations would have decreased from 15 to 4 in the fixed-timing cohort.CONCLUSIONS: Older age, left ventricle ejection fraction, and the absence of hypertension increase the risk of time-density curve truncation. However, a CTA test-dose-directed case-specific protocol can reduce truncation to ensure accurate data while mitigating radiation dose increases.AUCarea under the curveDLPdose-length productLCOlow cardiac outputrLVEFreduced left ventricular ejection fractionTDCtime density curve