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Title: [Applied research of "quadri-low" combined with automatic tube current modulation and iterative model reconstruction technology in head and neck CT angiography].
Author: Cai W, Hu CH, Wang XM, Hu S, Bao J, Gong JP, Fan GH, Zhang W, Shi D, Qian MH.
Journal: Zhonghua Yi Xue Za Zhi; 2018 Jan 02; 98(1):30-35. PubMed ID: 29343026.
Abstract:
Objective: To investigate the feasibility of low tube voltage, low contrast medium concentration, injection rate and volume (quadri-low) combined with automatic tube current modulation (ATCM) and iterative model reconstruction (IMR) technology in head and neck CT angiography (CTA). Methods: A total of 70 patients whose body mass index (BMI)<25 kg/m(2) underwent head and neck CTA and digital subtraction angiography (DSA) from January to July 2017 were enrolled in this prospective study. According to random number table, patients were divided into two groups: group A (n=35) was scanned according to the protocol of 120 kV, 150 mAs, 50 ml and 5 ml/s iopromide (370 mg/ml) and filtered back projection (FBP) reconstruction; group B (n=35) was scanned with 80 kV, ATCM with mean tube current of 100 mAs, 30 ml and 3 ml/s iohexol (300 mg/ml) and IMR; the other parameters kept consistent between the two groups. The maximum transverse neck diameter at the level of the hyoid bone, artery CT value and image noise were measured, signal to noise ratio (SNR), contrast to noise ratio (CNR) and figure of merit (FOM) were calculated, and the image quality was evaluated subjectively and compared with those reconstructed by DSA. Scan length, volume CT dose index (CTDIvol) and dose length product (DLP) were recorded, and the effective dose (ED) was calculated. The chi-square and independent-sample t tests were used to compare the inter-group differences in these aforementioned data. Resutls: No significant difference was found in general information between the two groups. No significant difference existed in artery CT value, image noise, SNR and CNR between the two groups (t=-1.170-1.365, all P>0.05); however, the FOM of group B (74±40) was significantly higher than that in group A (12±4) (Z=-7.195, P=0.000). The image quality of the two groups met the requirement of clinical diagnosis[(4.1±0.7) vs (4.2±0.8) points, Z=-0.592, P>0.05], no significant difference was found in subjective evaluation and diagnostic efficacy. The CTDIvol, DLP and ED in group B were all significantly lower than those in group A (Z=-7.728, -7.202, -7.206, all P<0.05). The iodine load and iodine delivery rate (IDR) of group B was lower than that of group A (18.5 g vs 9.0 g, 1.85 mg/s vs 0.90 mg/s), and they were reduced for 51.4% in group B. Conclusions: For patients of BMI <25 kg/m(2,) low tube voltage, low contrast medium concentration, injection rate and volume combined with ATCM and IMR technology can significantly decrease radiation dose, iodine load and IDR while maintain the image quality in head and neck CTA examination. 目的： 探讨低电压和低对比剂浓度、注射速率及注射剂量的"四低"技术，联合自动管电流调节(ATCM)和全模型迭代重建(IMR)技术在头颈部CT血管成像(CTA)中的可行性。 方法： 2017年1至7月于苏州大学附属第一医院前瞻性收集70例因需行头颈部CTA和数字减影血管造影(DSA)检查且体质指数(BMI)<25 kg/m(2)的患者纳入研究。按随机数字表将受试者分为A、B两组，每组各35例。A组采用120 kV、固定管电流为150 mAs、50 ml及5 ml/s对比剂碘普胺(含碘370 mg/ml)和滤波反投影(FBP)重建；B组采用80 kV、平均管电流为100 mAs的ATCM技术、30 ml及3 ml/s对比剂碘海醇(含碘300 mg/ml)和IMR；其余扫描参数2组一致。测量并计算舌骨层面最大直径、动脉CT值、噪声、信噪比(SNR)、对比噪声比(CNR)和图像灵敏度(FOM)，并对图像质量进行主观评价及与DSA结果对照。记录扫描长度、容积CT剂量指数(CTDIvol)和剂量长度乘积(DLP)，计算有效剂量(ED)。对2组间数据结果分别采用χ(2)检验、两独立样本t检验来进行比较。 结果： 2组患者一般资料具有可比性。2组图像动脉CT值、噪声、SNR和CNR差异均无统计学意义(t＝－1.170～1.365，均P>0.05)；但B组FOM明显高于A组(74±40比12±4，Z＝－7.195，P＝0.000)。2组图像质量均符合临床诊断要求[(4.1±0.7)比(4.2±0.8)分，Z＝－0.592，P>0.05]，主观评价及诊断效能的差异均无统计学意义。B组CTDIvol、DLP和ED均低于A组，差异均有统计学意义(Z＝－7.728、－7.202、－7.206，均P<0.05)；A、B组对比剂碘摄入量分别为18.5、9.0 g，对比剂碘流率分别为1.85、0.90 mg/s，B组较A组均减少51.4%。 结论： 对于BMI<25 kg/m(2)患者，采用低电压和低对比剂浓度、注射速率及注射剂量联合ATCM和IMR技术行头颈部CTA检查，在保证图像质量的同时明显降低了辐射剂量和对比剂碘摄入量及碘流率。.

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