Quantitative breast tissue characterization using grating-based x-ray phase-contrast imaging.

X-ray phase-contrast imaging has received growing interest in recent years due to its high capability in visualizing soft tissue. Breast imaging became the focus of particular attention as it is considered the most promising candidate for a first clinical application of this contrast modality. In this study, we investigate quantitative breast tissue characterization using grating-based phase-contrast computed tomography (CT) at conventional polychromatic x-ray sources. Different breast specimens have been scanned at a laboratory phase-contrast imaging setup and were correlated to histopathology. Ascertained tumor types include phylloides tumor, fibroadenoma and infiltrating lobular carcinoma. Identified tissue types comprising adipose, fibroglandular and tumor tissue have been analyzed in terms of phase-contrast Hounsfield units and are compared to high-quality, high-resolution data obtained with monochromatic synchrotron radiation, as well as calculated values based on tabulated tissue properties. The results give a good impression of the method's prospects and limitations for potential tumor detection and the associated demands on such a phase-contrast breast CT system. Furthermore, the evaluated quantitative tissue values serve as a reference for simulations and the design of dedicated phantoms for phase-contrast mammography.

[Therapy monitoring of neoadjuvant therapy with MRI. RECIST and functional imaging]. / Therapiemonitoring im MRT unter neoadjuvanter Therapie. RECIST und funktionelle Bildgebung.

CLINICAL/METHODICAL ISSUE: Neoadjuvant chemotherapy is increasingly being applied in patients with operable breast cancer. Thus, an early prediction of response to neoadjuvant chemotherapy is of high relevance. STANDARD RADIOLOGICAL METHODS: The interobserver variability of clinical examination, mammography and ultrasonography in the assessment of response to neoadjuvant chemotherapy is high. METHODICAL INNOVATIONS: Magnetic resonance imaging (MRI) allows the assessment of functional parameters in addition to changes in tumor size and morphology. PERFORMANCE: A reliable therapy response monitoring aims at optimizing individualized patient care. ACHIEVEMENTS: This paper summarizes current guidelines for the assessment of response to neoadjuvant chemotherapy in breast cancer according to the response evaluation criteria in solid tumors (RECIST). Furthermore, the technical principles of MRI-based therapy monitoring are described and an overview of the clinical studies that have assessed the feasibility of functional MRI in response to treatment evaluation is given. PRACTICAL RECOMMENDATIONS: The technology of functional MRI offers promising results concerning therapy response monitoring. However, the level of evidence is not sufficiently evaluated for the technologies of functional MRI presented here.

[Phase contrast imaging of the breast. Basic principles and steps towards clinical implementation]. / Phasenkontrastbildgebung der Brust. Grundlagen und Schritte zur klinischen Implementierbarkeit.

CLINICAL/METHODICAL ISSUE: Breast cancer is the most common cancer and the leading cause of cancer deaths in women worldwide. STANDARD RADIOLOGICAL METHODS: Mammography is the only imaging technique approved for nationwide breast cancer screening. Digital full field mammography has improved mammographic image quality. Nevertheless, mammography has a low positive predictive value and a low sensitivity especially in mammographically dense breasts. One of the major limitations is the inherently low contrast between healthy breast parenchyma and breast cancer. METHODICAL INNOVATIONS: Phase contrast imaging is based on the phase shift that occurs when X-rays encounter a change in refractive index between different materials. PERFORMANCE: The improved soft tissue contrast makes the technology particularly promising for breast diagnostics. ACHIEVEMENTS: The studies presented here suggest that phase contrast imaging provides additional diagnostic information both using phase contrast mammography and phase contrast computed tomography (CT). PRACTICAL RECOMMENDATIONS: This paper provides an overview of the basic principles of the phase contrast imaging and describes recent developments towards in vivo and ex vivo phase contrast imaging of the breast.

X-ray phase-contrast imaging of the breast--advances towards clinical implementation.

Breast cancer constitutes about one-quarter of all cancers and is the leading cause of cancer death in women. To reduce breast cancer mortality, mammographic screening programmes have been implemented in many Western countries. However, these programmes remain controversial because of the associated radiation exposure and the need for improvement in terms of diagnostic accuracy. Phase-contrast imaging is a new X-ray-based technology that has been shown to provide enhanced soft-tissue contrast and improved visualization of cancerous structures. Furthermore, there is some indication that these improvements of image quality can be maintained at reduced radiation doses. Thus, X-ray phase-contrast mammography may significantly contribute to advancements in early breast cancer diagnosis. Feasibility studies of X-ray phase-contrast breast CT have provided images that allow resolution of the fine structure of tissue that can otherwise only be obtained by histology. This implies that X-ray phase-contrast imaging may also lead to the development of entirely new (micro-) radiological applications. This review provides a brief overview of the physical characteristics of this new technology and describes recent developments towards clinical implementation of X-ray phase-contrast imaging of the breast.

[Limits of mammography screening: current controversies and perspectives]. / Grenzen des Mammographiescreenings : Aktuelle Kontroversen und Perspektiven.

In recent years overdiagnosis has been claimed to be a major disadvantage of breast cancer screening. Studies estimating overdiagnosis have shown substantial discrepancies due to differences in the underlying epidemiological methods. Valid estimates based on studies with sufficient follow-up have shown a proportion of overdiagnosis of much less than 10 % of cancer detected by screening. Special attention should be given to intraductal carcinoma in situ as it is a precursor lesion of invasive cancer but the progression potential is poorly understood and it is currently treated similarly to invasive cancer. This highlights the urgent need for better stratification of the disease in research and clinical practice allowing individual risk-adapted appropriate therapy. In this respect new molecular and genetic biomarkers seem to be the most promising approach for predicting disease behavior.Interval carcinoma represents a limitation of breast cancer screening and the impact on screening effectiveness is still unknown. Recent studies have emphasized that interval carcinoma is more aggressive than cancer detected by screening. Hence the occurrence and distribution of interval cancer should be recorded accurately by national cancer registries and evaluated by the screening services. Quality assurance measures may help to reduce the rate of false negative cases to a minimum. Further research focusing on subgroups of screening participants with a higher risk for interval cancer occurrence seems to be a prerequisite for developing future prevention strategies.

[Certification of breast centers]. / Zertifizierung von Brustzentren.

The primary focus of the establishment and certification of specialized cancer centers in the context of the National Cancer Plan is to improve the quality of care for patients with various carcinoma entities. The era of organ center certification started with the establishment of specialized breast cancer centers in line with the high incidence of breast cancer, the high mortality rate and the high level of interdisciplinary cooperation in the diagnosis and therapy of breast cancer. The introduction of quality management and external monitoring aims to provide high quality care in the diagnosis and therapy of breast cancer and is expected to improve long-term quality data (disease-free survival and overall survival) and to reduce mortality rates by about 25-30%. Certification requires the implementation of a quality management system and care provision structures assuring diagnosis and therapy according to the quality guidelines and recommendations of the specialist societies. Basic requirements for improving the quality of breast cancer patient care are centralization, specialization and interdisciplinarity. It has been demonstrated that the improvement of overall survival is associated with an increasing annual case load of a center, an increasing case load per surgeon per year, study participation and interdisciplinarity. Tumor documentation will be harmonized in the future by the establishment of local clinical cancer registries and cross-linking them with the National Cancer Registry. The data collection and analysis of several quality markers and current follow-up and survival data for each breast cancer patient will allow direct comparison of participating institutions. Individual breast cancer centers may demonstrate quality improvement longitudinally. Both certification and specialization require additional services which are associated with a substantial increase in costs. Preliminary data suggest that certified breast cancer centers are dependent on cross-financing by the participating departments of a hospital. Up to now cost-effective analyses for certified breast cancer centers are not available due to a substantial lack of data defining the additional financial burden.

[Digital breast tomosynthesis : technical principles, current clinical relevance and future perspectives]. / Digitale Brusttomosynthese : Technische Grundlagen, aktuelle klinische Relevanz und Perspektiven für die Zukunft.

In recent years digital full field mammography has increasingly replaced conventional film mammography. High quality imaging is guaranteed by high quantum efficiency and very good contrast resolution with optimized dosing even for women with dense glandular tissue. However, digital mammography remains a projection procedure by which overlapping tissue limits the detectability of subtle alterations. Tomosynthesis is a procedure developed from digital mammography for slice examination of breasts which eliminates the effects of overlapping tissue and allows 3D imaging of breasts. A curved movement of the X-ray tube during scanning allows the acquisition of many 2D images from different angles. Subseqently, reconstruction algorithms employing a shift and add method improve the recognition of details at a defined level and at the same time eliminate smear artefacts due to overlapping structures. The total dose corresponds to that of conventional mammography imaging. The technical procedure, including the number of levels, suitable anodes/filter combinations, angle regions of images and selection of reconstruction algorithms, is presently undergoing optimization. Previous studies on the clinical value of tomosynthesis have examined screening parameters, such as recall rate and detection rate as well as information on tumor extent for histologically proven breast tumors. More advanced techniques, such as contrast medium-enhanced tomosynthesis, are presently under development and dual-energy imaging is of particular importance.

[Automated breast volume scanner (ABVS) : a new approach for breast imaging]. / Automated-breast-volume-Scanner (ABVS) : Eine neue Methode zur Mammadiagnostik.

The automated breast ultrasound technique has been known for a long time but did not play an important role in diagnostics due to its inferior sensitivity for small solid lesions with low frequency transducers and its uncomfortable examination technique with the patients in a supine position and the breast immersed in water. The automated breast volume scanner (AVBS) is a high-end ultrasound scanner which employs frequencies of 5-14 MHz and consists of a flexible arm with the transducer at the end, a touchscreen and a 3D workstation. The scan is performed with the patient in the prone position. Depending on the breast size, various presettings are available from which the examiner may select the most appropriate. AVBS has various major advantages, such as being independent from the experience of the operator as well as supplying consistent and reproducible results. Additionally, for the first time it became possible to obtain coronal images of the complete breast, which greatly assists the planning of surgical interventions. In this article the ABVS technique will be described and results will be illustrated by means of clinical examples.

[Importance of mammography, sonography and MRI for surveillance of neoadjuvant chemotherapy for locally advanced breast cancer]. / Wertigkeit von Mammographie, Sonographie und MRT zur Verlaufsbeurteilung der neoadjuvanten Chemotherapie bei lokal fortgeschrittenem Mammakarzinom.

PURPOSE: The aim of this study is to give an overview on the surveillance of response to neoadjuvant chemotherapy in locally advanced breast cancer with mammography, ultrasound and breast MRI. MATERIAL AND METHODS: The results of a recently presented study on surveillance in the course of chemotherapy with contrast-enhanced MRI are compared with ratings based on mammography and ultrasound. RESULTS: Contrast-enhanced MRI correlates best with the histological tumor size when compared with mammography and ultrasound. Tumors with a high HER2 score (2+ with positive FISH test or 3+) show a significantly higher response compared to tumors with a lower HER2 score: size p <0.01, maximum enhancement p <0.01 and area under the curve (AUC) p <0.05. Reduction of tumor size and enhancement are complementary parameters and are not correlated to each other (r=0.22). DISCUSSION: Contrast-enhanced MRI of the breast is a reliable method for quantification of the response to neoadjuvant chemotherapy. The reductions of tumor size and of tumor enhancement are not correlated. Therefore, it may be reasonable to take both aspects for quantification of therapy response into account. Further studies are needed for evaluation of the value of breast MRI as a prognostic factor.

[Modern gray-scale sonography of the breast]. / Moderne B-Bild-Sonographie der Mamma.

Recently, the diagnosis of breast diseases by ultrasound has changed radically. It is no longer a complementary modality to mammography but a separate method to investigate breast disease. Innovative high-resolution ultrasound allows more specific diagnosis of breast tumors. Tissue-harmonic imaging not only uses the transmitted, fundamental frequency to obtain an image but also the harmonic frequency. The harmonic signal is processed by the ultrasound system with the result of better delineation of tissue structures and spatial compounding assembles an image from multiple images taken from different angles of echo waves. The effect is the reduction of artifacts with optimized contrast. Finally the advanced speckle reduction technique is used to smooth and homogenize the image. Additionally continuous advancement of new high-resolution linear transducers is responsible for the essential improvement of image quality. In conclusion, it is recommended to integrate all of the described modalities in order to obtain diagnostically conclusive image quality. This article demonstrates the new techniques and applications exemplified using images.

[An unusual breast tumor]. / Ein ungewöhnlicher Mammatumor.

The presented case shows how difficult it can be to diagnose rare diseases if they present with masses in atypical locations. In an extensive further diagnostic workup other characteristic findings then point to the correct diagnosis.

[Interventional MRI of the breast. Indications, technique, results and perspectives]. / MR-gestützte Interventionen in der Mammadiagnostik. Indikationen, Techniken, Ergebnisse und Perspektiven.

With the use of diagnostic MR imaging of the breast MR guided minimal invasive interventions are increasingly needed to obtain histologic proof of lesions, that are occult at mammography and ultrasound. MR guided interventions are time consuming and expensive. Therefore it is necessary to insure, that the diagnostic MR examination of the referring institution establishing the indication for biopsy is of high quality.Assuming accurate patient selection percutaneous MR vacuum-assisted biopsy is a safe and accurate method for the evaluation of even small enhancing breast lesions. Up to now the imaging of the biopsy procedure itself is not possible due to a lack of compatibility of the biopsy needle. Careful reviewing of imaging and pathologic findings is therefore recommended. Several newly developed MR compatible devices will allow more precise placement and imaging of the biopsy needle. Procedure times will be reduced. For the evaluation of additional enhancing lesions in patients with breast carcinoma referred for operation the preoperative wire localization is remaining a wide-spread safe and simple method.

[Value of breast MRI as supplement to mammography and sonography for high risk breast cancer patients]. / Wertigkeit der Mamma-MRT als Ergänzung zu Mammographie und Sonographie bei Patientinnen mit erhöhtem Mammakarzinomrisiko.

PURPOSE: The aim of this study is to give an overview on early detection of breast cancer in patients with an increased risk of breast cancer. Sensitivities and diagnostic accuracies of breast MRI, mammography and ultrasound were compared. MATERIAL AND METHODS: A systematic literature search of the past 3 years was performed. Studies which compared breast imaging modalities and used image-guided biopsy results as standard of reference were included. Patients included had to have had an increased lifetime risk for breast cancer (>15%). RESULTS: Regarding sensitivity and diagnostic accuracy, breast MRI performed best in comparison to the other modalities within this collective of patients. Sensitivities ranged from 71-100%, 0-78%, and 13-65%, for MRI, mammography, and ultrasound, respectively CONCLUSION: Breast MRI is a well established tool for screening in patients at high risk for developing breast cancer and is a valuable supplement to mammography and ultrasound within this selected cohort of patients.

[Functional MR-pancreatography with secretin. A comparison of imaging quality and diagnostic value]. / Funktionelle MR-Pankreatikographie mit Sekretin--Intraindividueller Vergleich von Abbildungsqualität und Diagnoserelevanz.

PURPOSE: The aim of the present study was to assess imaging improvement and diagnostic value of secretin stimulated MR-pancreatography (MRP) compared to conventional MRP. MATERIALS AND METHODS: 50 patients were studied with a 1.0 T system using a single-shot-TSE sequence (RARE). Imaging quality and diameter of the different parts of the pancreatic tract and diagnoses were monitored before and after secretin. RESULTS: The visualization of the normal main pancreatic duct (MPD) was improved significantly in head, body and tail. Side branches were not depicted at all. Even in chronic pancreatitis a significant improvement of imaging quality could be observed, but only in patients without duct dilation before secretin. In advanced disease with duct dilation, secretin stimulation provided no further diagnostic improvement. CONCLUSIONS: In conclusion, secretin increases the diagnostic value of MRP especially in patients with normal or non-dilated native MPD and may help to avoid unnecessary invasive procedures such as ERCP.

[Chronic infections of the biliary system]. / Chronische Infektionen im Bereich des Gallensystems.

Chronic inflammation of the gallbladder and the biliary tract due to infections are rare, compared to common cholelithiasis and acute biliary inflammation. This group of diseases includes, besides of chronic cholecystitis with cholelithiasis, also chronic gallbladder inflammation without stones, gallbladder hydrops and porcelain gallbladder. The most common form of chronic biliary tract infection is primary sclerosing cholangitis, while infection due to parasites like oriental cholangiohepatitis is very rare in Europe. Using imaging modalities like ultrasonography, computed tomography and magnetic resonance imaging, normally, besides of porcelain gallbladder, only indirect signs of the disease may be documented. However, when i.v. cholangiography, endoscopic-retrograde cholangiography, percutaneous transhepatic cholangiography or MR-cholangiography are performed, depiction, especially of the biliary tree, is feasible. Differentiation of benign stricture and malignant tumor stenosis is problematic unrelated to the imaging modality used. Due to the unspecific signs of the disease, diagnosis may not be made from imaging alone, but a clinical suspicion may be strengthened.