Low-Voltage, High-Pitch Computerized Tomography Angiography of the Infrarenal Aorta and Lower Extremity Vessels: Assessment of Radiation Dose, Image Quality With Hybrid Iterative Reconstruction, and Efficacy of Test Injection Using a Monitoring Scan at Knee Level.

OBJECTIVES: Our aim was to assess image quality and radiation dose of low-voltage high-pitch computed tomography angiography of the infrarenal aorta and lower extremities and evaluate the efficacy of test injection technique using a monitoring scan at knee level. METHODS: A total of 60 patients with suspected peripheral arterial disease were divided into 2 groups: group 1 (30 patients, 80 kVp, high pitch [3.2], and hybrid iterative reconstruction [sinogram-affirmed iterative reconstruction]) and group 2 (30 patients, 120 kVp, low pitch [1.0], and filtered back projection reconstruction). The test injection technique at knee level was used to determine the scan delay time in group 1. The image quality and radiation exposure were compared. RESULTS: There were significant differences between the 2 groups in mean (SD) arterial attenuation (80 vs 120 kVp: 507.78 [103.01] vs 317.54 [62.03] Hounsfield units, P < 0.001), mean (SD) signal-to-noise ratio (51.04 [20.29] vs 34.66 [9.94], P < 0.001), and contrast-to-noise ratio (44.83 [17.93] vs 28.26 [9.60], P < 0.001). No difference in subjective image quality was found between the 2 groups (all P > 0.05). The imaging time was significantly shorter in group 1 (2.70 [0.11] vs 14.65 [0.90s], P < 0.001). The mean (SD) effective dose was significantly lower in the 80 kVp group (0.76 [0.06] vs 4.29 [0.63] mSv, P < 0.001). CONCLUSIONS: The 80-kVp high-pitch computed tomography angiography of the lower limbs using sinogram-affirmed iterative reconstruction yields reduction of radiation exposure as well as obtains acceptable image quality if acquisition protocols are used in conjunction with the test injection technique using monitoring scan at knee level to determine the delay time.

[Associations of triple-phase enhancement multi-slice CT scan with histological differentiation and lymphovascular invasion in gastric cancer].

OBJECTIVE: To explore the associations of triple-phase enhancement multi-slice CT scan with histological differentiation and lymphovascular invasion in advanced gastric cancer. METHODS: Patients with gastric cancer undergoing surgical resection between January 2006 and December 2009 were included, all of whom underwent routine and two-phase contrast enhancement multi-slice CT examinations of the upper abdomen before surgery. Patients with incomplete data were excluded. Postoperative specimens were used for evaluation of histological differentiation, microscopic lymphovascular invasion, and CD34 and D2-40 expression. Associations between contrast enhancement ratio (CER) of triple-phase multi-slice CT scan and differentiation as well as lymphovascular invasion were analyzed. RESULTS: A total of 64 patients were included. There were significant associations between CER and tumor differentiation (P<0.05). Compared to those without microvascular invasion, CER of the arterial phase in gastric cancer with microvascular invasion was significantly higher (0.61±0.28 vs. 0.46±0.14, P<0.05), and that of the arterial-parenchymal phase was significantly lower(1.81±0.39 vs. 2.28±0.80, P<0.05). However, gastric cancers with lymphatic invasion were associated with significantly higher CER of the parenchymal phase than their counterparts(1.25±0.57 vs. 1.00±0.35, P<0.05). CONCLUSION: CER of triple-phase multi-slice CT scan can reveal the differentiation of gastric cancer and is associated with microvascular and lymphatic invasion.

Multi-slice CT contrast-enhanced presentations of advanced gastric cancer: associations with histo-differentiation and expression of p53 and P-glycoprotein.

BACKGROUND: This study aimed to investigate multi-slice CT contrast-enhanced presentation of gastric cancer and its correlation with histo-differentiation and p53 and P-glycoprotein (P-gp) expression. METHODS: Sixty-six patients with gastric cancer in the present study underwent a multi-slice CT preoperative routine and dual-phase contrast-enhanced examination of the upper abdomen; postoperative specimens were used to determine histo-differentiation and the expression of p53 and P-gp. The correlation of multi-slice CT contrast-enhanced presentation with histo-differentiation and expression of p53 and P-gp was analyzed. RESULTS: The dual-phase contrast-enhanced ratio (CER) was not correlated with the histo-differentiation of gastric cancer (P > 0.05). Positive expression of p53 and P-gp was significantly higher in the cases of layered or heterogeneous enhancement than in the cases of homogenous enhancement (P < 0.05). Positive expression of p53 was also correlated with the arterial phase CER, tumor size and lymph node metastasis (P < 0.05), but not with infiltration thickness of the gastric wall, nor was it correlated with the portal phase CER (P > 0.05). Positive expression of P-gp was only correlated with the portal phase CER (P = 0.005). CONCLUSIONS: Differently enhanced pattern and CER of the arterial and portal phase in gastric cancer correlate with its different histo-differentiation and expression of p53 and P-gp respectively. In addition, tumor size and lymph node metastasis of gastric cancer relate to the expression of p53.