Computer vision analysis of collagen fiber bundles in the adventitia of human blood vessels

Numerical simulations, which are based on reliable biomechanical models of blood vessels, can help to get a better understanding of cardiovascular diseases such as atherosclerosis, and can be used to develop optimal medical treatment strategies.The adventitia is the outer most layer of blood vessels and its mechanical properties are essentially determined by the three-dimensional, structural arrangement of collagen fibre bundles embedded in the tissue. Global information such as the orientation statistics of the fibre bundles as well as detailed information as the crimp of the single fibres within the bundles is of particular interest in biomechanical modeling.In order to obtain a sufficiently large amount of data for biomechanical modeling, a fully automatic method for the structural analysis of the soft tissue is required. In this contribution we present methods based on computer vision to fulfill this task. We start by discussing proper tissue preparation and imaging techniques that have to be used to obtain data, which reliably represents the real three-dimensional tissue structure. The next step is concerned with algorithms that robustly segment the collagen fibre bundles and cope with various kinds of artifacts. Novel segmentation techniques for robust segmentation of individual fibril bundles and methods for estimation of their parameters, such as location, shape, mean fibril orientation, crimp of fibrils, etc, is discussed. The proposed algorithms are based on novel perceptual grouping methods operating on the extracted orientation data of fibrils.Finally, we demonstrate the results obtained by our fully automatic method on real data. In addition, for a more quantitative assessment, we introduce a generative structural model that enables the synthesis of three-dimensional fibre bundles with well-defined characteristics.

Anisotropic Mechanical Properties of Tissue Components in Human Atherosclerotic Plaques

Knowledge of the biomechanical properties of human atherosclerotic plaques is of essential importance for developing more insights in the pathophysiology of the cardiovascular system and for better predicting the outcome of interventional treatments such as balloon angioplasty. Available data are mainly based on uniaxial tests, and most of the studies investigate the mechanical response of fibrous plaque caps only. However, stress distributions during, for example, balloon angioplasty are strongly influenced by all components of atherosclerotic lesions. A total number of 107 samples from nine human high-grade stenotic iliac arteries were tested; associated anamnesis of donors reported. Magnetic resonance imaging was employed to test the usability of the harvested arteries. Histological analyses has served to characterize the different tissue types. Prepared strips of 7 different tissue types underwent cyclic quasistatic uniaxial tension tests in axial and circumferential directions; ultimate tensile stresses and stretches were documented. Experimental data of individual samples indicated anisotropic and highly nonlinear tissue properties as well as considerable interspecimen differences. The calcification showed, however, a linear property, with about the same stiffness as observed for the adventitia in high stress regions. The stress and stretch values at calcification fracture are smaller (179±56 kPa and 1.02±0.005) than for each of the other tissue components. Of all intimal tissues investigated, the lowest fracture stress occurred in the circumferential direction of the fibrous cap (254.8±79.8 kPa at stretch 1.182±0.1). The adventitia demonstrated the highest and the nondiseased media the lowest mechanical strength on average.

Single lamellar mechanics of the human lumbar anulus fibrosus

The mechanical behavior of the entire anulus fibrosus is determined essentially by the tensile properties of its lamellae, their fiber orientations, and the regional variation of these quantities. Corresponding data are rare in the literature. The paper deals with an in vitro study of single lamellar anulus lamellae and aims to determine (i) their tensile response and regional variation, and (ii) the orientation of lamellar collagen fibers and their regional variation. Fresh human body-disc-body units (L1-L2, n=11) from cadavers were cut midsagittally producing two hemidisc units. One hemidisc was used for the preparation of single lamellar anulus specimens for tensile testing, while the other one was used for the investigation of the lamellar fiber orientation. Single lamellar anulus specimens with adjacent bone fragments were isolated from four anatomical regions: superficial and deep lamellae (3.9+/-0.21 mm, mean +/- SD, apart from the outer boundary surface of the anulus fibrosus) at ventro-lateral and dorsal positions. The specimens underwent cyclic uniaxial tensile tests at three different strain rates in 0.15 mol/l NaCl solution at 37 degrees C, whereby the lamellar fiber direction was aligned with the load axis. For the characterization of the tensile behavior three moduli were calculated: E(low) (0-0.1 MPa), E(medium) (0.1-0.5 MPa) and E(high) (0.5-1 MPa). Additionally, specimens were tested with the load axis transverse to the fiber direction. From the second hemidisc fiber angles with respect to the horizontal plane were determined photogrammetrically from images taken at six circumferential positions from ventral to dorsal and at three depth levels. Tensile moduli along the fiber direction were in the range of 28-78 MPa (regional mean values). Superficial lamellae have larger E(medium) (p=0.017) and E(high) (p=0.012) than internal lamellae, and the mean value of superficial lamellae is about three times higher than that of deep lamellae. Tensile moduli of ventro-lateral lamellae do not differ significantly from the tensile moduli of dorsal lamellae, and E(low) is generally indifferent with respect to the anatomical region. Tensile moduli transverse to the fiber direction were about two orders of magnitude smaller (0.22+/-0.2 MPa, mean +/- SD, n=5). Tensile properties are not correlated significantly with donor age. Only small viscoelastic effects were observed. The regional variation of lamellar fiber angle phi is described appropriately by a regression line |phi|=23.2 + 0.130 x alpha (r(2)=0.55, p<0.001), where alpha is the polar angle associated with the circumferential position. The single anulus lamella may be seen as the elementary structural unit of the anulus fibrosus, and exhibits marked anisotropy and distinct regional variation of tensile properties and fiber angles. These features must be considered for appropriate physical and numerical modeling of the anulus fibrosus.

Discrepancies in current practice of pathological evaluation of sentinel lymph nodes in breast cancer. Results of a questionnaire based survey by the European Working Group for Breast Screening Pathology

AIMS

To evaluate aspects of the current practice of sentinel lymph node (SLN) pathology in breast cancer via a questionnaire based survey, to recognise major issues that the European guidelines for mammography screening should address in the next revision.

METHODS

A questionnaire was circulated by mail or electronically by the authors in their respective countries. Replies from pathology units dealing with SLN specimens were evaluated further.

RESULTS

Of the 382 respondents, 240 European pathology units were dealing with SLN specimens. Sixty per cent of these units carried out intraoperative assessment, most commonly consisting of frozen sections. Most units slice larger SLNs into pieces and only 12% assess these slices on a single haematoxylin and eosin (HE) stained slide. Seventy one per cent of the units routinely use immunohistochemistry in all cases negative by HE. The terms micrometastasis, submicrometastasis, and isolated tumour cells (ITCs) are used in 93%, 22%, and 71% of units, respectively, but have a rather heterogeneous interpretation. Molecular SLN staging was reported by only 10 units (4%). Most institutions have their own guidelines for SLN processing, but some countries also have well recognised national guidelines.

CONCLUSIONS

Pathological examination of SLNs throughout Europe varies considerably and is not standardised. The European guidelines should focus on standardising examination. They should recommend techniques that identify metastases > 2 mm as a minimum standard. Uniform reporting of additional findings may also be important, because micrometastases and ITCs may in the future be shown to have clinical relevance.

Consistency of staining and reporting of oestrogen receptor immunocytochemistry within the European Union—an inter-laboratory study

To assess the variability of oestrogen receptor (ER) testing using immunocytochemistry, centrally stained and unstained slides from breast cancers were circulated to the members of the European Working Group for Breast Screening Pathology, who were asked to report on both slides. The results showed that there was almost complete concordance among readers (kappa=0.95) in ER-negative tumours on the stained slide and excellent concordance among readers (kappa=0.82) on the slides stained in each individual laboratory. Tumours showing strong positivity were reasonably well assessed (kappa=0.57 and 0.4, respectively), but there was less concordance in tumours with moderate and low levels of ER, especially when these were heterogeneous in their staining. Because of the variation, the Working Group recommends that laboratories performing these stains should take part in a external quality assurance scheme for immunocytochemistry, should include a tumour with low ER levels as a weak positive control and should audit the percentage positive tumours in their laboratory against the accepted norms annually. The Quick score method of receptor assessment may also have too many categories for good concordance, and grouping of these into fewer categories may remove some of the variation among laboratories.

The course of serum HER-2/neu levels as an independent prognostic factor for survival in metastatic breast cancer

The purpose of this study was to determine the impact of serum HER-2/neu level dynamics during the course of disease and treatment on the prognosis of patients with metastatic breast cancer. Two thousand and thirty-eight serum samples collected sequentially after disease relapse in 286 patients with metastatic breast cancer were measured by Bayer Immuno 1 trade mark assay retrospectively for serum HER-2/neu (cut-off level 15 ng/ml). One hundred and five patients (37%) presented with serum HER-2/neu continuously </=15 ng/ml after disease recurrence, 71 (25%) had continuously elevated levels and 110 patients (38%) had both non-elevated and elevated values in the course of metastatic breast cancer. Patients with continuously elevated serum HER-2/neu levels had a significantly poorer survival after disease recurrence compared to patients with continuously or temporarily non-elevated serum HER-2/neu values (log-rank test: p<0.001). Including the number of palliative antitumor therapies and therapy response in Cox regression analysis, serum HER-2/neu dynamics revealed to be an independent prognostic factor for survival. In conclusion, 63% of 286 patients with metastatic breast cancer demonstrated either continuously or temporarily elevated serum HER-2/neu levels. Decrease of elevated serum HER-2/neu to levels </=15 ng/ml and levels continuously </=15 ng/ml during the course of disease correlated significantly with longer survival.

Bilateral carcinomas of the breast with local recurrence: analysis of genetic relationship of the tumors

Local recurrence of bilateral breast carcinomas is rare, but of biological interest, since it is unclear as to which tumor the local recurrence is related to, the ipsilateral or the contralateral, or whether it is an independent neoplasm. The aim of this study was to investigate the genetic relationship of bilateral breast carcinomas to each other and to their local recurrences. Eight cases of bilateral breast carcinomas, five with and three without local recurrence were analyzed using a microsatellite assay for 13 microsatellite loci. The presence of loss of heterozygosity and microsatellite instability in the various tumors was used for clonal analysis. All eight bilateral breast carcinomas showed divergent alterations in at least two microsatellite loci, which ruled out a genetic relationship. Four of five local recurrences were genetically related to the ipsilateral tumor and unrelated to the contralateral tumor. Only one local recurrence that occurred 11.8 years after the surgery of an infiltrative lobular carcinoma simultaneously with distant metastases was genetically related to the contralateral breast carcinoma. Although the number of cases in our study is limited, there is evidence that local recurrence of bilateral breast carcinoma frequently arises from the ipsilateral tumor.

Expression of androgen receptors in benign and malignant endometrial stromal neoplasms

Several studies have shown that endometrial stromal neoplasms express estrogen and progesterone receptors (ER, PR). To our knowledge, the presence or absence of androgen receptors (AR) in these rare uterine neoplasms has not been investigated. Tumors ( n=20)-3 endometrial stromal nodules, 14 low-grade endometrial stromal sarcomas (ESS, low grade), and 3 high-grade endometrial sarcomas (undifferentiated endometrial sarcoma, UES)-were studied. Immunohistochemical analyses for ER, PR, and AR were performed on formalin-fixed, paraffin-embedded archival material. Positive immunoreactions for ER and PR were observed in 14 (70%) and 17 (85%) cases, respectively. Furthermore, 9 cases (45%) were positive for AR. Among 17 ESS and UES cases, 7 (41%) revealed positivity for AR. Two of three benign stromal nodules were also positive for AR. Moreover, one of the three high-grade sarcomas (undifferentiated endometrial sarcoma) was negative for both ER and PR, but showed positive reaction for AR. In summary, ARs are expressed in 45% of endometrial stromal neoplasms. In addition to determination of ER and PR, the results of immunohistochemical examination of AR in these rare uterine tumors may have some impact on the postoperative management of the patients.

Cytopathology in Austria

Cervical cancer screening developed rapidly during the 1970s. Today, approximately 1.5 million smears are taken annually, so 50% of the target population are screened every year, 30% are cytologically underserved (24% never had a smears, 6% only once). This figure correlates with the fact that there are still 30% deaths from cervical cancer compared with 1960. Since 1998 a voluntary quality assurance programme was introduced by the Austrian Society of Cytology, based on comparison of results reported from participating laboratories.

Change of HER-2/neu status in a subset of distant metastases from breast carcinomas

It is assumed that HER-2/neu status remains consistent in breast carcinoma during metastatic spread, but in most previous studies primary tumours were compared with concurrent regional lymph node metastases. The present study investigated 31 breast carcinomas and their corresponding lymph node and distant metastases for HER-2/neu status by immunohistochemistry (HercepTest) and fluorescence in situ hybridization (FISH) (PathVysion). In 14 cases, serum HER-2/neu (SHER-2) was measured sequentially using the Bayer Immuno 1 HER-2/neu assay. Comparing HER-2/neu immunohistochemistry of primary tumours and distant metastases case by case, increased HER-2/neu expression was found in the distant metastases in 15 cases (48.4%), three (9.7%) of which showed an increase from score 0 to score 3+. In contrast, lymph node metastases showed the same HER-2/neu expression as the primary tumours, confirmed by FISH. Two cases, which showed HER-2/neu score 3+ and HER-2/neu amplification in the primary tumours, revealed increased SHER-2 levels above 50 ng/ml at the first measurement. Five of the 14 cases (36%) showed an increase of SHER-2 above 50 ng/ml towards the end of the patients' life. On the basis of these results, there is evidence that in a subset of breast carcinomas, HER-2/neu amplification and overexpression occur de novo in distant metastases at a late disease stage.

Androgen receptors frequently are expressed in breast carcinomas: potential relevance to new therapeutic strategies

BACKGROUND

Several studies have demonstrated the biologic and therapeutic significance of estrogen and progesterone receptors (ER and PR) in breast carcinomas. The aim of the current study was to examine the presence of androgen receptors (AR) in breast carcinomas.

METHODS

Two hundred cases of breast carcinoma, consisting of 145 invasive and 55 noninvasive (ductal carcinoma in situ [DCIS]) lesions, were examined using a monoclonal antibody against AR on formalin-fixed, paraffin-embedded archival material. The results were analyzed for correlations with immunohistochemically determined ER, PR, and HER-2/neu expression.

RESULTS

Eighty-seven of the 145 cases (60%) of invasive carcinoma and 45 of the 55 cases (82%) of DCIS were AR-positive according to internationally standardized guidelines. The vast majority of Grade 1 carcinomas were positive for AR (90% of invasive Grade 1 carcinomas and 95% of Grade 1 DCIS), whereas in Grade 3 invasive carcinomas and DCIS, positive immunoreactions for AR were observed in 46% and 76% of cases, respectively. Among the cases of Grade 3 carcinoma, 33 invasive carcinomas (39%) and 17 DCIS lesions (68%) were ER-negative but AR-positive. Among Grade 1 carcinomas (invasive and DCIS), not a single case was positive for HER-2/neu, but most cases were intensely positive for AR. In contrast, many invasive Grade 3 carcinomas exhibited agreement between AR status and HER-2/neu status (AR-positive and HER-2/neu-positive, 30.5%; AR-negative and HER-2/neu-negative, 42.5%).

CONCLUSIONS

Androgen receptors are commonly expressed in DCIS and in invasive breast carcinoma. A significant number of poorly differentiated carcinomas are ER-negative and PR-negative but AR-positive. Immunohistochemical examination of AR would be desirable because it would provide additional information about steroid receptors in breast carcinomas.

Pathological work-up of sentinel lymph nodes in breast cancer. Review of current data to be considered for the formulation of guidelines

Controversies and inconsistencies regarding the pathological work-up of sentinel lymph nodes (SNs) led the European Working Group for Breast Screening Pathology (EWGBSP) to review published data and current evidence that can promote the formulation of European guidelines for the pathological work-up of SNs. After an evaluation of the accuracy of SN biopsy as a staging procedure, the yields of different sectioning methods and the immunohistochemical detection of metastatic cells are reviewed. Currently published data do not allow the significance of micrometastases or isolated tumour cells to be established, but it is suggested that approximately 18% of the cases may be associated with further nodal (non-SN) metastases, i.e. approximately 2% of all patients initially staged by SN biopsy. The methods for the intraoperative and molecular assessment of SNs are also surveyed.

How to improve microscopic images obtained with consumer-type digital cameras

AIM

Digital imaging is useful in conventional photography because it immediately provides images, and the image quality can be improved afterwards by the use of computer programs. The major disadvantages of consumer-type digital cameras mounted on microscopes are (i) unequal illumination through the image, and (ii) a coloured background. A computer program was specifically adapted and refined to improve images obtained with consumer-type digital cameras mounted on microscopes.

METHODS AND RESULTS

An approach using a division operation between the specimen image and a background image leads to homogeneous illumination throughout the image, with automatically corrected brightness and white background. The correct colour spectrum is preserved by correction of the histogram. This approach was obtained from the freeware computer program 'Image Arithmetic'. In a test, three different consumer-type digital cameras (Sony, Nikon, Olympus) on different microscopes were used to obtain images of different types of histological specimens (cervical smear, bone marrow biopsy, and colonic biopsy). The computer program dramatically improved the quality of images obtained with all tested cameras.

CONCLUSION

Using this approach, even low-cost digital cameras mounted on microscopes produce brilliant images with homogeneous illumination and a white background, the image quality being comparable with expensive cameras especially designed for microscopes.

Quality assurance for detection of estrogen and progesterone receptors by immunohistochemistry in Austrian pathology laboratories

Steroid hormone receptors are important prognostic and predictive factors in breast carcinomas. Thus their determination is of essential importance. The aims of this study were to assess the quality of the immunohistochemical assays, and to assess the interlaboratory and interobserver variability performed by different laboratories in Austria. Ten unstained slides for interlaboratory variability evaluation and ten immunohistochemically prestained slides for interobserver variability evaluation from breast carcinomas known to show different degrees of steroid hormone receptor expressions were sent to 32 surgical pathology laboratories in Austria (participation rate 97%). The participants were requested to perform their in-house immunohistochemistry (IHC) technique for estrogen receptors (ERs) and progesterone receptors (PRs) on the unstained slides. All slides were evaluated by estimating percentage and intensity of stained nuclei semiquantitatively. From these data the Reiner, Remmele and the Allred scores were calculated. A less than 10% cut-off level was chosen as threshold for positive cases. Regarding the series of prestained slides, both sensitivity and specificity were very high (>96.88%); false-positive and -negative rates were low (<3.31%). Interobserver variability showed moderate multirater kappa values concerning the ER (Reiner score: kappa=0.57) and PR scores (Reiner score: kappa=0.53). The agreement among observers was better for negative cases than positive cases. In-house slides representing interlaboratory variability showed fair to moderate kappa values concerning the ER and PR scores (kappa for ER Reiner score=0.41; PR=0.32). In this slide series, sensitivity and specificity were high (>82.2%) and false-positive or -negative rates were low in ER cases (<3.03) and moderately low in PR cases (17.46%). These results demonstrate that variability is higher when participants use their own staining method. In more detailed analysis, the automated IHC techniques showed an advantage over manual techniques concerning interlaboratory variability. There exists no difference in reproducibility with respect to scoring systems for steroid hormone receptor estimation.

Microsatellite analysis of breast carcinoma and corresponding local recurrences

Local recurrence is a serious complication of breast carcinoma that reduces quality of life and influences prognosis. The aim of this study was to determine whether local recurrences of breast carcinoma are genetically related to the primary tumours. Forty cases of locally recurrent breast carcinomas (median onset: 3.6 years after primary surgery) were analysed: 22 patients had undergone breast-conserving therapy and 18 mastectomy. Eighteen microsatellites on chromosomes 2p, 3p, 5q, 10q, 11p, 11q, 13q, 17q, 17p, 18p were amplified by PCR using fluorescent-labelled primers, automatically detected after polyacrylamide gel electrophoresis and analysed for loss of heterozygosity (LOH) or microsatellite instability (MSI). Follow-up data were available for 39 cases with a median value of 89 months. All LOH and MSI found in the primary tumours were also present in the corresponding recurrences, indicating that they are genetically related to the primary tumours and not secondary malignancies in the same breast. MSI was found in three cases, of which one harboured MSI at more than two loci. The median value of LOH per case was significantly higher in the recurrent (four per case) compared to the primary tumours (two per case; p < 0.001, Mann-Whitney test), reflecting the genotype of tumour progression. Early local recurrence was associated with specific LOH for TP53.15 (p = 0.018, log-rank test) in the primary tumours. LOH on D13S1699 or D17S855 was associated with lymph node metastases (p = 0.024 and p = 0.019, respectively; chi-square test). In addition, tumour grade, lack of oestrogen or progesterone receptor expression, young patient age and early appearance of local recurrence significantly correlated with poor survival. The development of local recurrence despite clear resection margins may result from residual DCIS distant from the invasive carcinoma, homing of circulating tumour cells, or genetically altered, histologically normal breast tissue not immediately adjacent to the invasive carcinoma.

Mechanics of the human femoral adventitia including the high-pressure response

Adventitial mechanics were studied on the basis of adventitial tube tests and associated stress analyses utilizing a thin-walled model. Inflation tests of 11 nonstenotic human femoral arteries (79.3 +/- 8.2 yr, means +/- SD) were performed during autopsy. Adventitial tubes were separated anatomically and underwent cyclic, quasistatic extension-inflation tests using physiological pressures and high pressures up to 100 kPa. Associated circumferential and axial stretches were typically <20%, indicating "adventitiosclerosis." Adventitias behaved nearly elastically for both loading domains, demonstrating high tensile strengths (>1 MPa). The anisotropic and strongly nonlinear mechanical responses were represented appropriately by two-dimensional Fung-type stored-energy functions. At physiological pressure (13.3 kPa), adventitias carry ~25% of the pressure load in situ, whereas their circumferential and axial stresses were similar to the total wall stresses (~50 kPa in both directions), supporting a "uniform stress hypothesis." At higher pressures, they became the mechanically predominant layer, carrying >50% of the pressure load. These significant load-carrying capabilities depended strongly on circumferential and axial in-vessel prestretches (mean values: 0.95 and 1.08). On the basis of these results, the mechanical role of the adventitia at physiological and hypertensive states and during balloon angioplasty was characterized.

Insulinoma of the pancreas with insular-ductular differentiation in its liver metastasis--indication of a common stem-cell origin of the exocrine and endocrine components

We describe an insulinoma of the pancreas in a 56-year-old patient, which showed insular-ductular differentiation in its liver metastasis. Although the primary tumor was uniformly endocrine in nature with insulin production, the metastasis contained two distinct cell types in organoid arrangement. One cell type was insulin-positive and was arranged in islet-like structures; the other was insulin-negative but distinctly pan-cytokeratin and cytokeratin 7 positive and arranged in ducts. In the primary tumor and the metastasis, the tumor cells were surrounded by a desmoplastic stroma. As to the histogenesis of the tumor and its metastasis, we discuss the following possibilities: (1) the tumor cells might derive from a common stem cell that matures into two phenotypically different cell lines, resembling the situation in embryogenesis and (2) one tumor cell type originates from the other by transdifferentiation (metaplasia). We conclude that the parallel occurrence of endocrine and ductal differentiation supports the concept that, under certain conditions, islet cells and ductular cells may also originate from islets and that mixed endocrine/exocrine pancreatic tumors do not necessarily arise from totipotent duct cells but might also have a primary endocrine cell origin.

Lack of Pseudomelanosis coli in colonic adenomas suggests different pathways of apoptotic bodies in normal and neoplastic colonic mucosa

Pseudomelanosis coli is characterized by pigment deposition in the lamina propria and caused by increased epithelial apoptosis. Pseudomelanosis coli is absent in colonic neoplasia. The aim of our studies was to investigate this phenomenon in more detail. Apoptotic fragments of epithelial cells and their distribution, cell proliferation (Ki-67, MIB 1 immunostaining), macrophages (CD68 immunostaining), Bcl-2 expression and apoptosis [terminal-deoxynucleotidyl-transferase mediated dUTP fluorescein nick end labeling (TUNEL) assay] were studied in adenomas arising in normal and melanotic colonic mucosa, in normal colonic mucosa and colonic mucosa with pseudomelanosis alone. In adenomas, we found 7.0 apoptotic bodies per 100 epithelial cells in the epithelial layer and only 0.2 apoptotic bodies per high power field (HPF) in the lamina propria. In contrast, in melanotic mucosa 1.7 apoptotic bodies per 100 epithelial cells in the epithelial layer and 2.5 per HPF in the lamina propria were found. Our results show that apoptotic fragments remain in the neoplastic (adenomatous) epithelium and do not reach (at least in higher amounts) the lamina propria. They can, therefore, not contribute to the development of pseudomelanosis in these lesions. However, macrophages are diminished in adenomas. Proliferation (Ki-67) and also Bcl-2 expression are highly increased in adenomas. The pathway of mucosal macrophages is also discussed.