[en] Objective: To evaluate the degree of contrast enhancement, reduction of radiation exposure and contrast dose requirement of low-kV 64-slice CT angiography (MSCTA). Methods: Iopamidol solutions with 370 mgI/mL diluted to concentrations of 1.5% and 2.5% were placed in 30 rubber tubes each with tube diameter of 2 mm to simulate large blood vessels. The 30 tubes with 1.5% Iopamidol solution were scanned on a 64-slice CT scanner using the same tube current of 40 mA and varying tube voltages of 120 kV, 100 kV and 80 kV. All 1.25 mm-thick slices were transferred to an ADW4.3 workstation. The CT densities of different slices from the 30 tubes were measured ten times to calculate the average CT densities for the 3 different tube voltages. The radiation doses with different scanning parameters were recorded as CTDIvol The 30 tubes with 2.5% Iopamidol solution were then scanned and analyzed using the same scanning parameters and data processing method. Results: With 1.5% Iopamidol concentration, there was significant (P < 0.05) difference in the average CT densities among 120 kV (172.23 HU), 100 kV (208.64 HU) and 80 kV (262.05 HU). The same statistical trend was found with 2.5% Iopamidol concentration. The CTDIvol of 120 kV, 100 kV and 80 kV were 2.68 mGy, 1.66 mGy and 0,83 mGy, respectively. There was no significant difference between average CT densities of 1.5% Iopamidol concentration scanned at 80 kV (262.05 HU) and that of 2.5% Iopamidol scanned at 120 kV (267.35 HU). All rubber tubes had similar tube brightness, image detail and VR image definition. Conclusions: With decreasing kV in 64-slice CT scanning, the CT density increases whereas changing the tube current with constant tube voltage does not affect the CT density. Low kV scanning is important in reducing the dose of X-ray radiation and contrast agent. (authors)

[en] Objective: To evaluate the clinical role of ¹⁸F fluorodeoxyglucose(FDG)-positron emission tomography (PET) in the diagnosis of breast tumor. Methods: ¹⁸F-FDG PET/CT was performed on 45 patients with suspected breast cancer. The ¹⁸F-FDG PET/CT images were analyzed visually and semi-quantitatively by calculating the maximum standardized uptake values (SUVmax). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the two evaluating methods were compared with histology. Results: Of the 45 lesions, 8 were benign and 37 were malignant with lymphadenopathy in 17 patients. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 91.2%, 87.5%, 97.1%, 70%, 91.1%, respectively for cut-off SUVmax of 2.5 compared to 89.2%, 62.5%, 91.7%, 55.6%, 84.4% by visual assessment. Conclusions: PET/CT may be useful in differentiating benign and malignant breast tumors. (authors)