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BackgroundRadiofrequency ablation (RFA) is one of the most promising non-surgical treatments for hepatic tumors. The assessment of the therapeutic efficacy of RFA is usually obtained by visual comparison of pre- and post-treatment CT images, but no numerical quantification is performed.MethodsIn this work, a novel method aiming at providing a more objective tool for the evaluation of RFA coverage is described. Image registration and segmentation techniques were applied to enable the visualization of the tumor and the corresponding post-RFA necrosis in the same framework. In addition, a set of numerical indexes describing tumor/necrosis overlap and their mutual position were computed.ResultsAfter validation of segmentation step, the method was applied on a dataset composed by 10 tumors, suspected not to be completed treated. Numerical indexes showed that only two tumors were totally treated and the percentage of a residual tumor was in the range of 5.12%-35.92%.ConclusionsThis work represents a first attempt to obtain a quantitative tool aimed to assess the accuracy of RFA treatment. The possibility to visualize the tumor and the correspondent post-RFA necrosis in the same framework and the definition of some synthetic numerical indexes could help clinicians in ameliorating RFA treatment.
Aims and background Women with BRCA1 or BRCA2 germline mutations have an elevated risk of developing breast and/or ovarian cancer. Because of the early onset of the disease, screening of this group of women should start at an earlier age than in the general population. The association of breast magnetic resonance imaging (BMRI) and ultrasonography (US) with mammography (MX) and clinical breast examination (CBE) in the regular surveillance of these individuals has been proposed and seems to improve the early detection of breast cancer. Methods Within a multicenter study started by the Istituto Superiore di Sanita (Rome), at the Istituto Nazionale Tumori of Milan (INT) we enrolled 116 women at high genetic risk for breast cancer; they were either BRCA1 or BRCA2 mutation carriers or had a strong family history of breast cancer. They underwent CBE, MX, US and BMRI once a year. Results Between June 2000 and April 2005, at INT 12 cancers were detected among the 116 screened individuals (10%). In this subgroup, 1 patient refused BMRI and in 2 cases US was not performed. With BMRI we found 11 cancers and 6 of them were detectable only by this technique. In these 6 cases, the size of the disease was less than 1 cm and MX was false negative due to irregularly nodular parenchyma in 4 cases and scar tissue or prosthesis in the other 2. US was not performed in 2 cases and was false negative in 4 cases. Three false positive results were found with BMRI: 1 case was considered suspect but related to hormonal influences; 1 case with the same pattern was sent for second-look US, which gave a negative result and BMRI review after 6 months showed normalization of the parenchyma; in the third case histology revealed the presence of adenosis. No false positive results were registered for MX. Conclusions The aim of secondary prevention is the detection of cancer at its earliest stage. BMRI screening in women with BRCA1 or BRCA2 mutations or at high familiar risk appears to be highly sensitive and may detect mammographically occult disease. The accuracy of MR imaging is higher than that of conventional imaging but the technique is flawed by a lower specificity. In order to avoid unnecessary biopsies we believe that the combination of BMRI and conventional imaging can be very useful in screening women with a high genetic risk of breast cancer, especially with second-look evaluation by means of US when BMRI yields the only positive diagnostic result. Second-look US has been demonstrated to be of critical importance both in recognizing false positive BMRI results and in guiding biopsies, when necessary.
Due to its infiltrative growth associated to only limited connective tissue reaction, lobular carcinoma often encounters difficulties in mammographic diagnosis. In contrast, MRI can be very helpful in evaluating the true extension of the disease, especially when breast conservation is considered. Due to a more consistent fibrotic stroma, these lesions sometimes show a delayed enhancement, which suggests that more than one set of subtracted images should be evaluated during MRI analysis.
A fundamental question in surgery of only magnetic resonance imaging (MRI)-detected breast lesions is to ensure their removal when they are not palpable by clinical examination and surgical exploration. This is especially relevant in the case of small tumors, carcinoma in situ or lobular carcinoma. Thirty-nine patients were enrolled in the study, 21 patients with breast lesions detected by both conventional imaging and breast MRI (bMRI) and 18 patients with bMRI findings only. Preoperative bMRI allowed staging the disease and localizing the lesion. In the operating theater, contrast medium was injected 1 minute before skin incision. After removal, surgical specimens were submitted to ex vivo MRI, performed using a dedicated surface coil and Spair inversion recovery sequences for suppression of fat signal intensity. All MRI enhancing lesions were completely included within the surgical specimen and visualized by ex vivo MRI. In the first 21 patients, bMRI was able to visualize branching margins or satellite nodules around the core lesion, and allowed for better staging of the surrounding in situ carcinoma; in the last 18 patients, eight of whom were breast cancer type 1 susceptibility protein (BRCA) mutation carriers, bMRI identified 12 malignant tumors, otherwise undetectable, that were all visualized by ex vivo MRI. This is the first description of a procedure that re-enhances breast lesions within a surgical specimen, demonstrating the surgical removal of nonpalpable breast lesions diagnosed only with bMRI. This new strategy reproduces the morphology and the entire extension of the primary lesion on the specimen, with potentially better local surgical control, reducing additional unplanned surgery.
Although an overlap in the enhancement behavior of malignant and some benign lesions is clearly evident, a careful interpretation of MR images is helpful in detecting and mainly ruling out breast cancer combined with mammographically suspicious microcalcifications.
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