Quantitative accuracy of computed tomography perfusion under low-dose conditions, measured using a hollow-fiber phantom

• Published in: Japanese journal of radiology Vol. 35; no. 7; pp. 373 - 380
• Main Authors: Suzuki, Kazufumi, Hashimoto, Hiroyuki, Okaniwa, Eiji, Iimura, Hiroshi, Suzaki, Shingo, Abe, Kayoko, Sakai, Shuji
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 01.07.2017; Springer Nature B.V
• Subjects: Absorption; Accuracy; Algorithms; Blood flow; Blood volume; Brain; Cerebral blood flow; Cerebrovascular Circulation; Computed tomography; Computer simulation; Confidence intervals; Contrast Media; Cranium; Deconvolution; Dilution; Humans; Imaging; Medicine; Medicine & Public Health; Noise; Nuclear Medicine; Original Article; Perfusion; Phantoms, Imaging; Radiation Dosage; Radiology; Radiotherapy; Reproducibility of Results; Tomography; Tomography, X-Ray Computed - methods; Transit time; X-rays; Deconvolution algorithm; Phantom; Time-concentration curve; Computed tomography perfusion
• ISSN: 1867-1071; 1867-108X
• DOI: 10.1007/s11604-017-0642-y

Purpose The purpose of this study was to investigate the quantitative accuracy under low-dose conditions on computed tomography (CT) perfusion using a hollow-fiber phantom that had the theoretical absolute values of perfusion indices. Materials and methods Our phantom comprised two components, i.e., a hollow-fiber hemodialyzer to pump the diluted contrast material and a surrounding syringe-shaped X-ray-absorbing body to simulate the absorption of X-rays by a brain and cranium. We performed CTP scans on the phantom under various dose conditions ranging from 20 to 140 mA using a 64-row CT scanner, measuring experimental cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP) values using a deconvolution algorithm. Results The theoretical value of the CBV was within the 95% confidence interval of CBV values measured under 80 mA. The CBV measured under low-dose settings and all CBF values measured were smaller than the theoretically calculated ones, and all MTT values measured were larger. All measured values of the CBV, CBF, MTT, and TTP decreased with an increase in image noise under lower dose conditions. Conclusion It is difficult to define a low-dose limit in clinical scan conditions because of the complex characteristics of perfusion indices.