The Clinical Value Of128-Slice Spiral CT With The Technology Of Low Tube Voltage And Low Dosage Of Contrast In The Lower Extremity Arterial Diseases

Background Recently, with the ageing of the population and the popularity of diabetes, the incidence of lower limb arteriosclerosis disease has rised significantly. The lesions of lower extremity arteries were evaluated by means of digital subtraction angiography (DSA), the golden standard, but because of its high cost and complications such as faults, the diagnostic role of DSA has been increasingly replaced in lower limb vascular diseases. Ultrasound can also display lower limb blood vessels, but due to its low spatial resolution as well as being affected by the operator experiences, it fails to provide surgeons with the overall view of vessels picture, so it is difficult to carry on the accurate preoperative evaluation. Magnetic Resonance angiography (MRA) with noninvasive nature and no radiation will overestimate the vascular stenosis. The spatial resolution of small vessel the MRA is also significantly lower than that of the CTA. At the same time, more contraindication, longer operating time, and incapability to show vascular calcification also restricted MRA. Due to the spread of the multi slice spiral computed tomography (MSCT) because of its noninvasiveness, shorter acquisition time and image post-processing advantages, CT angiography (CTA) has become an important means to check lower extremity artery disease. However, due to the large range of CT scans, the effective radiation dose increases, leading to a potential risk to the patients. On the other hand, the contrast medium has the adverse reactions such as renal toxicity to human body, so reduction of the dosage of contrast agent is becoming more and more attentive. This research adopts the128slices spiral CT with low tube voltage and low contrast medium technology in patients with lower extremity artery disease in order to discuss the clinical value of the technology to reduce the radiation dose and the contrast agent.Objective Mainly to explore the clinical value of128-Slice spiral CT with the technology of low tube voltage and low dosage of contrast in the lower extremity arterial diseases; At the same time, we also focused on the application value of low contrast medium.,Methods Sixty patients with lower extremity arterial diseases underwent CTA examinations with the technology of low tube voltage and low dosage of contrast (80kV), including12cases performed with digital subtraction angiography (DSA) after one week. Transmit the images to the workstation for image post-processing, and the image quality is analysed. CT values of femoral artery, popliteal artery, posterior tibial artery rectus femoris and its standard deviation(SD) of every patient were recorded for three time and calculate the mean attenuation. To calculate the signal to noise ratios(SNR) and contrast-to-Noise ratios(CNR). We recorded CT dose volume index (CTDIvoI) and dose length product (DLP) to obtain the effective dose (ED). For comparison, SNR, CNR, CTDIvol, DLPandED of60cases with routine dose (120kv and150mAs) were counted up between January2012and November2012.Two radiologists evaluated the image quality with5points methods subjectively, including the clarity of lower limb artery cross section and all reconstruction image, display degree of blood vessels, the overall image quality, etc. We used SPSS17.0for statistical analysis, including independent samples t test, single factor variance test (one-way ANOVA).The scores were conducted consistency test with Kappa. On the basis of DSA, calculate the sensitivity, specific degrees, accuracy, positive predictive value, negative predictive value of the CTA of12patients with routine DSA examination. Results With low kV (80kV) scanning,39cases with double lower limbs arteriosclerosis and luminal stenosis, partial occlusion (ASO) were checked out, and4cases of arteriovenous fistula,15cases of thrombosis angiitis obliterans(TAO) of lower limb artery,1case of lower limb artery malformation,1case of forced bilateral popliteal fossa depression syndrome were found. Compared with DSA of12patients, the sensitivity of the CTA using lower tube voltage (80kV) in the diagnosis of lower limb artery stenosis and occlusion was99.3%, Specific degrees was95.2%, the accuracy was98.5%, positive predictive value was98.7%, negative predictive value of97.7%.The average CT values of80kV and120kV groups are:533.42±63.00HU,63.00±46.95HU, the former increased significantly compared with the latter. The mean values(80kV) of CTDIvoI, DLP and ED were4.88±0.00mGy、602.85±42.00mGy.cm、9.05±0.63mSv,and the mean values(120kV) of CTDIvoI, DLP, ED were10.07±0.00mGy,1282.80±61.81mGy. Cm,19.20±0.88mSv. The former radiation dose reduced nearly50%than the latter. The average scores of A physician to80kv and120kv group were4.32±0.54,4.37±0.58, and B physician’s average score were4.33±0.53,4.42±0.54, and the difference between80kV and120kV grouphas no statistical significance, and both of them have good consistency (Kappa=0.921,P=0.00).Conclusion The technology of low tube voltage and low dosage of contrast in the lower extremity arterial CTA examination significantly reduces the radiation dose and the dose of contrast medium, with the diagnosable images. Therefore, there is a great prospect in clinical application with regard to the diagnosis and follow-up of the lower extremity arterial diseases.