Ramgren Birgitta, Björkman-Burtscher Isabella M, Holtås Stig, Siemund Roger
Center for Medical Imaging and Physiology, Skåne University Hospital, Lund, Sweden.
Acta Radiol. 2012 Oct 1;53(8):929-34. doi: 10.1258/ar.2012.120218. Epub 2012 Aug 17.
Computed tomography angiography (CTA) of intracranial arteries has high demands on image quality. Important parameters influencing vessel enhancement are injection rate, concentration of contrast media and tube voltage.
To evaluate the impact of an increase of contrast media concentration from 300 to 400 mg iodine/mL (mgI/mL) and the effect of a decrease of tube voltage from 120 to 90 kVp on vessel attenuation and image quality in CT angiography of intracranial arteries.
Sixty-three patients were included into three protocol groups: Group I, 300 mgI/mL 120 kVp; Group II, 400 mgI/mL 120 kVp; Group III, 400 mgI/mL 90 kVp. Hounsfield units (HU) were measured in the internal carotid artery (ICA) and the M1 and M2 segments of the middle cerebral artery. Image quality grading was performed regarding M1 and M2 segments, volume rendering and general image impression.
The difference in mean HU in ICA concerning the effect of contrast media concentration was statistically significant (P = 0.03) in favor of higher concentration. The difference in ICA enhancement due to the effect of tube voltage was statistically significant (P < 0.01) in favor of lower tube voltage. The increase of contrast medium concentration raised the mean enhancement in ICA with 18% and the decrease of tube voltage raised the mean enhancement with 37%. Image quality grading showed a trend towards improved grading for higher contrast concentration and lower tube voltage. Statistically significant better grading was found for the combined effect of both measures except for general impression (P 0.01-0.05).
The uses of highly concentrated contrast media and low tube voltage are easily performed measures to improve image quality in CTA of intracranial vessel.
颅内动脉计算机断层血管造影（CTA）对图像质量要求很高。影响血管强化的重要参数包括注射速率、造影剂浓度和管电压。
评估颅内动脉CT血管造影中造影剂浓度从300毫克碘/毫升（mgI/mL）增加以及管电压从120千伏峰值（kVp）降低对血管衰减和图像质量的影响。
63例患者被纳入三个方案组：第一组，300 mgI/mL 120 kVp；第二组，400 mgI/mL 120 kVp；第三组，400 mgI/mL 90 kVp。在内颈动脉（ICA）以及大脑中动脉的M1和M2段测量亨氏单位（HU）。对M1和M2段、容积再现和总体图像印象进行图像质量分级。
关于造影剂浓度的影响，ICA中平均HU的差异具有统计学意义（P = 0.03），有利于较高浓度。由于管电压的影响，ICA强化的差异具有统计学意义（P < 0.01），有利于较低管电压。造影剂浓度的增加使ICA中的平均强化提高了18%，管电压的降低使平均强化提高了37%。图像质量分级显示，较高造影剂浓度和较低管电压的分级有改善趋势。除总体印象外，两种措施的联合效果在统计学上有显著更好的分级（P 0.01 - 0.05）。
使用高浓度造影剂和低管电压是提高颅内血管CTA图像质量的简便易行的措施。
