Quantitative analysis of elastography images in the detection of breast cancer.

PURPOSE: The aim of this study was to develop a quantitative method for breast cancer diagnosis based on elastosonography images in order to reduce whenever possible unnecessary biopsies. The proposed method was validated by correlating the results of quantitative analysis with the diagnosis assessed by histopathologic exam. MATERIAL AND METHODS: 109 images of breast lesions (50 benign and 59 malignant) were acquired with the traditional B-mode technique and with elastographic modality. Images in Digital Imaging and COmmunications in Medicine format (DICOM) were exported into a software, written in Visual Basic, especially developed to perform this study. The lesion was contoured and the mean grey value and softness inside the region of interest (ROI) were calculated. The correlations between variables were investigated and receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic accuracy of the proposed method. Pathologic results were used as standard reference. RESULTS: Both the mean grey value and the softness inside the ROI resulted statistically different at the t test for the two populations of lesions (i.e., benign versus malignant): p<0.0001. The area under the curve (AUC) was 0.924 (0.834-0.973) and 0.917 (0.826-0.970) for the mean grey value and for the softness respectively. CONCLUSIONS: Quantitative elastosonography is a promising ultrasound technique in the detection of breast cancer but large prospective trials are necessary to determine whether quantitative analysis of images can help to overcome some pitfalls of the methodic.

A mathematical approach for evaluating the influence of dose heterogeneity on TCP for prostate cancer brachytherapy treatment.

The low-dose-rate brachytherapy technique has proven suitable for the management of prostate cancer. However, published data generally report the clinical outcome and the minimum peripheral dose (mPD) to the target volume and not the actual dose distribution in patients. To this end, modern guidelines recommend the use of specific dose and volume indices describing dose distribution throughout the target. The introduction of a method, based on the standard linear quadratic model and Poisson statistics, entitled the F-factor allows the TCP from different DVHs to be calculated, by using the TCP from a uniform dose distribution as the reference. The F-factor sensitivity against radiobiological parameters and influence of the DVH were evaluated. We applied the F-formula on the post-plan DVHs of 58 patients treated with (125)I permanent seed implant brachytherapy for localized prostate cancer. F shows a strong correlation with dosimetric parameters already reported as significant predictors of the biochemical outcome.

The breast dynamic contrast enhanced MRI: preliminary results of a quantitative analysis.

The objective of our study was to apply a quantitative analysis to the dynamic contrast enhanced MR imaging of the breast. Automated criteria increase the objectivity and reproducibility of the diagnostic interpretation of the imaging for differentiating benign and malignant lesions. The validation of this applied method was evaluated by analysing the time- signal intensity curves and the performance of the extracted enhancement parameters. The performance of some extracted parameters was evaluated by ROC (Receiver Operating Characteristic) analysis. These parameters were found to be particularly accurate in differentiating lesions.

A possible quality control protocol for Doppler ultrasound for organizational time optimization.

Acceptance tests quantitatively determine equipment performance characteristics. Before a new probe is accepted, performance tests can be also used to compare performance of other probes. Routine performance tests verify device operational stability over the time. We developed an efficient and effective testing programme aiming to demonstrate changes in imaging performance relevant to clinical quantitative use of pulsed and colour Doppler. For each scanner-transducer tested, we introduced some quantitative and semi-quantitative parameters in relation to the clinical request for which the equipment was chosen. The proposed quantitative tests may also be used as qualitative tests, when it is suspected that scanner performance is deteriorating. The measurements, obtained with different units, differed also in the case of probes operating at the same depth and peak velocity. Without a quality control (QC) program, significant variations are likely to be reported when peak velocity of the same flow is measured with different instruments. Our experience suggests that modern digital equipments used in serial measurements may be stable over the time and that calibrated phantom may enable preventive identification of corrective action to units and probes. Manufacturers and independent laboratories applying a quality control protocol can increase our experience to recognize and deal with the involved problems.

MRI quality control tools for procedures and analyses.

Quality control in MRI includes acceptance tests on the installation of a new scanner and tests representative of the system's performance during clinical practice. The first tests are time consuming and carried out to evaluate the agreement of the system with the prescribed procurement specifications. The second tests identify the equipment malfunction requiring maintenance are not time consuming and are suited to a busy clinical scanner. The paper evaluates the feasibility of the AAPM protocols (1,2) and proposes procedures and practical tools to achieve this purpose. The MRI images, captured from the scanner and transferred in DICOM (Digital Imaging and Communications in Medicine) format by a local network, are analyzed by computerized worksheets and commercial software.

Electromagnetic interference by GSM cellular phones and UHF radios with intensive-care and operating-room ventilators.

The aim of this study was to evaluate the risks deriving from the interference by radio handsets (GSM cellular phones and UHF radios) with intensive-care and operating-room ventilators. Tests were conducted in three hospitals in Rome on 22 lung ventilators in accordance with the recommended practice ANSI C63.18-1997. When electromagnetic interference (EMI) effects occurred, the authors determined maximum interference distances. They also evaluated the distances at which the use of a given handset would result in a 5% and a 95% probability of interference. The degree of risk posed by each observed event was estimated, and safe distances are suggested. EMI events of varying degrees and natures were observed even with transmitters placed at a considerable distance. All observed effects were temporary. Only three ventilators of a certain model stopped working altogether and had to be reset.

A simple method to calculate the influence of dose inhomogeneity and fractionation in normal tissue complication probability evaluation.

PURPOSE: Since volumetric dose distributions are available with 3-dimensional radiotherapy treatment planning they can be used in statistical evaluation of response to radiation. This report presents a method to calculate the influence of dose inhomogeneity and fractionation in normal tissue complication probability evaluation. METHODS: The mathematical expression for the calculation of normal tissue complication probability has been derived combining the Lyman model with the histogram reduction method of Kutcher et al. [14] and using the normalized total dose (NTD) instead of the total dose. RESULTS: The fitting of published tolerance data, in case of homogeneous or partial brain irradiation, has been considered. For the same total or partial volume homogeneous irradiation of the brain, curves of normal tissue complication probability have been calculated with fraction size of 1.5 Gy and of 3 Gy instead of 2 Gy, to show the influence of fraction size. The influence of dose distribution inhomogeneity and alpha/beta value has also been simulated: considering alpha/beta = 1.6 Gy or alpha/beta = 4.1 Gy for kidney clinical nephritis, the calculated curves of normal tissue complication probability are shown. CONCLUSION: Combining NTD calculations and histogram reduction techniques, normal tissue complication probability can be estimated taking into account the most relevant contributing factors, including the volume effect.

Practical experience in electromagnetic hyperthermia quality control procedures within the context of international guidelines.

Recent international guidelines on hyperthermia (HT) quality assurance have pointed out the necessity of defining standard operative procedures and technical checks to guarantee an accurate performance of HT treatments. In the present paper, experience is described of quality control procedures that are performed in agreement with the more general guidelines concerning thermometry, sensor positioning, phantoms, applicator characterisation, and electromagnetic (EM) radiation leakage. This practical experience comes from the use of equipment for superficial and loco-regional HT working in the range 13.56-915 MHz.