Affected person inhabitants
This retrospective research was permitted by the Institutional Assessment Board, and all affected person necessities for knowledgeable consent had been waived. From June to July 2023, 47 sufferers who underwent CTP at our establishment for numerous causes, together with follow-ups for suspected stroke and/or intravascular ailments, had been reviewed. The exclusion standards had been as follows: (1) had a historical past of iodine allergy; (2) being pregnant(3) had extreme cardiac, hepatic, pulmonary, or renal dysfunction or hematological problems; and (4) had vital imaging artifacts. Affected person intercourse, age, physique weight, and top had been assessed and documented.
Scan protocols and reconstruction strategies
The acquisitions had been carried out utilizing a 320-row detector CT scanner (Aquilion ONE Genesis Version, Canon Medical Programs, Japan). The affected person was positioned in a supine place with their arms resting on each side of the physique and head in a complicated place and was instructed to stay nonetheless all through the examination. The CTP scanning parameters and the distinction agent administration protocol are summarized in Desk 1. In accordance with our customary CTP protocol, all sufferers obtained a set 40-mL intravenous bolus of Iomeron, 370 mg iodine per mL, adopted by a 30-mL bolus of saline at an injection charge of 5 mL/s [15]. The CTP acquisition comprised 19 phases, together with one noncontrast scan (430 mA), three scans throughout the early arterial section (300 mA, each 2 s), six scans throughout the arterial section (420 mA, each 2 s), 4 scans throughout the late arterial section (300 mA, each 2 s), and 5 scans throughout the venous section (300 mA, each 5 s). CTP photos from every section had been reconstructed utilizing adaptive iterative dose discount through three-dimensional processing [AIDR 3D, kernel FC41].
Knowledge processing
The CTP information had been transferred to a devoted workstation (Canon console, Canon Medical Programs, Japan), the place a radiologist with 4 years of expertise in head and neck CTA imaging performed the picture processing. Following movement correction, the time decay curves of the center cerebral artery had been generated from the CTP information, leading to three distinct photos: a single-phase picture representing the height time level (CTApeak) and a time-resolved most depth projection picture (CTAtMIP), which displayed the three phases with the best intensification, and a time-resolved common picture (CTAtAve). Subsequently, the improved photos obtained on the time factors of single-phase peak enhancement had been imported into devoted software program (CE-boost, SURESubtraction Iodine map, Canon Medical Programs, Japan) to generate CE-boost photos.
Picture evaluation
Quantitative picture evaluation
The quantitative picture evaluation was carried out by a radiologist with 4 years of expertise in deciphering head and neck CTA photos. In every reconstruction sequence, 4 areas of curiosity (ROI) had been constantly positioned on the similar anatomical location by copying and pasting, together with the basilar artery (BA), proper and left inner carotid artery (ICAs), and mind stem (BS). The scale of the ROIs was optimized to reduce the impact of artifacts and arterial calcification whereas maximizing their protection space. Vessel noise and brainstem noise had been outlined as the usual deviations (SDs) of those measurements and had been recorded because the SDvessel and SDbrainstem, respectively. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) had been calculated utilizing the next formulation:
$$textual content{SNR }= {textual content{CT}}_{textual content{vessel}}/{textual content{SD}}_{textual content{vessel}}$$
$$textual content{CNR }= left({textual content{CT}}_{textual content{vessel}}-{textual content{CT}}_{textual content{brainstem}}proper)/{textual content{SD}}_{textual content{brainstem}}$$
Qualitative picture evaluation
The photographs had been independently evaluated by two radiologists specializing in head and neck CTA imaging, with 4 and 12 years of expertise respectively. The five-point Likert scale standards (Desk 2) [16] had been used to evaluate picture high quality. The radiologists had been blinded to the reconstruction approaches throughout picture analysis. Pictures from the 4 CT picture units had been randomly organized and reviewed after blinding affected person info. Standardized window width and stage settings had been utilized throughout all reconstruction sequences for every affected person. In circumstances the place a discrepancy occurred within the evaluation of picture high quality scores between the 2 readers throughout the collaborative studying course of, they engaged in deliberations to achieve a remaining consensus.
Radiation dose
The CT dose index (CTDIvol) and the dose size product (DLP) had been recorded for every affected person, whereas the efficient dose (ED) was calculated by multiplying the DLP with a conversion coefficient okay issue of 0.0021 (mSv•mGy−1•cm−1) particularly designed for head examinations [17].
Statistical evaluation
Statistical analyses had been carried out utilizing R software program (model 3.6.1). The normality of the information distribution was assessed utilizing the Shapiro–Wilk check. For nonnormally distributed information, the Friedman check was employed, adopted by a number of comparisons utilizing the Wilcoxon signed rank check. One-way repeated evaluation of variance (ANOVA) was utilized to check steady variables with a traditional distribution, and paired-samples t exams had been used for the next a number of comparisons. Bonferroni correction was utilized for these a number of comparisons. Statistical significance was thought of as a p worth < 0.05. The interobserver settlement of subjective picture evaluation was evaluated utilizing kappa statistics, with the next standards: 0–0.20, poor; 0.21–0.40, truthful; 0.41–0.60, average; 0.61–0.80, good; and 0.81–1.00, glorious.
