A new postprocessing algorithm was developed for the diagnosis of breast cancer using electrical impedance scanning. This algorithm automatically recognizes bright focal spots in the conductivity map of the breast. Moreover, this algorithm discriminates between malignant and benign/normal tissues using two main predictors: phase at 5 kHz and crossover frequency, the frequency at which the imaginary part of the admittance is at its maximum. The thresholds for these predictors were adjusted using a learning group consisting of 83 carcinomas and 378 benign cases. In addition, the algorithm was verified on an independent test group including 87 carcinomas, 153 benign cases and 356 asymptomatic cases. Biopsy was used as gold standard for determining pathology in the symptomatic cases. A sensitivity of 84% and a specificity of 52% were obtained for the test group.
Cathartic bowel preparation as part of CT colonography examination (CTC) can be uncomfortable or even dangerous for certain patient groups. Noncathartic CT colonography (i.e. without cathartic cleansing) including contrast-material fecal tagging can offer significant clinical advantages and can increase the screening compliance for colorectal cancer. Current techniques of conventional CTC with fecal tagging use "electronic cleansing" algorithms to remove the remaining tagged colonic contents from the images. In such cases these methods can give satisfactory results, but they face serious problems with the inferior tagging quality of noncathartic protocols. To overcome this fundamental problem, a completely new approach is proposed using both a two-layer dual~energy MDCT and a dedicated algorithmic cleansing method that utilizes the spectral information. Feasibility study was performed with a two-layer dual-energy MDCT which was utilized in clinical studies with oral intake of both iodine and barium contrast agents. The new method was compared to a conventional electronic cleansing technique. We show that the new approach is better at detecting highly dilute contrast agents in the colon, particularly where the tagged colonic content is mixed or adjacent to air regions. Therefore, the new technique may surmount the need for cathartic bowel preparation in CTC. I. FEASIBILITY STUDY AND THE ALGORITHMT HE study was performed on a prototype, single source dualenergy MDCT (Philips Healthcare) based on simultaneous acquisition of two-layer detectors. The first layer mainly absorbs the lower x-ray energy spectrum, while the second layer absorbs the rest, mainly the higher energy spectrum. Each layer has 32 detector rows and 50 cm full field of view. ).The data from each layer are independently reconstructed. In addition, a standard-like full spectrum CT image is reconstructed from the weighted raw signals of the two layers. The dual energy images contribute to better material separation. Practically, in low radiation dose the spectral information is sensitive to image noise. However, complementary information about densities and structures can be obtained from the full spectrum images with lower noise.We developed an algorithm that utilizes the three image sets to properly balance between compound identification, image noise and morphology preservation. The results are used in a segmentation process that subtracts the colonic content leaving it empty of residues. In addition, a superior identification of the colon walls is obtained. A key principle in the algorithm ( fig. I) is enforcing a priori partial correlation between the spectral and the morphological information sets since in many practical situations they are related. The correlation and filtration features are empirically controlled and optimized via a special form of an adaptive non-linear diffusion filter. We note that the concept of using the correlation between "functional" information and anatomical or morphological information is useful in several multimoda...
Contemporary reconstruction algorithms yield the potential of reducing radiation exposure by denoising coronary computed tomography angiography (CCTA) datasets. We aimed to assess the reliability of coronary artery calcium score (CACS) measurements with an advanced adaptive statistical iterative reconstruction (ASIR-CV) and model-based adaptive filter (MBAF2) designed for a dedicated cardiac CT scanner by comparing them to the gold-standard filtered back projection (FBP) calculations. We analyzed non-contrast coronary CT images of 404 consecutive patients undergoing clinically indicated CCTA. CACS and total calcium volume were quantified and compared on three reconstructions (FBP, ASIR-CV, and MBAF2+ASIR-CV). Patients were classified into risk categories based on CACS and the rate of reclassification was assessed. Patients were categorized into the following groups based on FBP reconstructions: 172 zero CACS, 38 minimal (1–10), 87 mild (11–100), 57 moderate (101–400), and 50 severe (400<). Overall, 19/404 (4.7%) patients were reclassified into a lower-risk group with MBAF2+ASIR-CV, while 8 additional patients (27/404, 6.7%) shifted downward when applying stand-alone ASIR-CV. The total calcium volume with FBP was 7.0 (0.0–133.25) mm3, 4.0 (0.0–103.5) mm3 using ASIR-CV, and 5.0 (0.0–118.5) mm3 with MBAF2+ASIR-CV (all comparisons p < 0.001). The concomitant use of ASIR-CV and MBAF2 may allow the reduction of noise levels while maintaining similar CACS values as FBP measurements.
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