Ductoscopic biopsy of papillary tumors in women with nipple discharge.
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Biopsy, Needle↗
Biomedical subjects
Peter M Schlag
Publications and source records attributed to Peter M Schlag.
Prognostic value of cytokeratin-positive bone marrow cells of gastric cancer patients.
BACKGROUND: Epithelial cells in the bone marrow of patients with gastric cancer suggest tumor dissemination; however, their prognostic implications are controversial. We prospectively evaluated the correlation of bone marrow findings, recurrence rate, and disease-free survival after long-term follow-up. METHODS: Bone marrow were aspirated from both iliac crests and stained with monoclonal cytokeratin (CK)-18 antibody in 209 patients before their initial operation. Patients were followed up for a median of 56 months. RESULTS: Overall, 39 (19%) of 209 patients and 15 (14%) of 109 R0-resected patients had CK-positive cells. CK-positive patients had more local, regional, and distant recurrence than CK-negative patients (P < .05). We found a significantly shorter disease-free survival (P < .05) in the patients with >2 CK-positive cells per 2 x 10(6) bone marrow cells (mean, 35 months) than in patients with 2 CK-positive cells per 2 x 10(6) bone marrow cells was an independent prognostic factor for tumor-related death (P < .05). CONCLUSIONS: Not only the mere presence of CK-positive epithelial cells in bone marrow, but also the cell number, correlates with prognosis. Our findings suggest that classifying CK-positive bone marrow cells in these patients will facilitate future studies.
Aged↗
The metastasis-associated gene S100A4 is a novel target of beta-catenin/T-cell factor signaling in colon cancer.
BACKGROUND & AIMS: Activation of the Wnt/beta-catenin pathway is frequently observed in colorectal cancers. Our aim was to elucidate the impact of gain-of-function beta-catenin on the metastasis-associated gene S100A4 in human colon cancer cell lines and tumors. METHODS: We analyzed cell lines heterozygous for gain-of-function and wild-type beta-catenin, and variants homozygous for gain- or loss-of-function mutation in beta-catenin, for S100A4 expression, cell motility, and in vivo metastasis. beta-catenin-mediated S100A4 promoter activation was tested by reporter assays. For human colon carcinomas, S100A4 expression, beta-catenin genotype, and metachronous metastasis were correlated. RESULTS: We identified S100A4 as the most regulated gene by gain-of-function beta-catenin using a 10K microarray. Cell lines with gain-of-function beta-catenin expressed up to 60-fold elevated S100A4 levels, displayed strongly increased migration and invasion in vitro, and induced metastasis in mice. S100A4 small interfering RNA, beta-catenin small interfering RNA, or dominant negative T-cell factor (TCF) knocked down S100A4 and blocked biological effects. S100A4 complementary DNA transfection increased migration and invasion. We identified a TCF binding site within the S100A4 promoter and demonstrated the direct binding of heterodimeric beta-catenin/TCF complexes. Reporter assays confirmed the beta-catenin-induced S100A4 promoter activity. Furthermore, S100A4 mRNA expression was increased in primary colon cancers, which later developed distant metastases, compared to non-metastasizing tumors. Colon tumors heterozygous for gain-of-function beta-catenin showed concomitant nuclear beta-catenin localization, high S100A4 expression, and metastases. CONCLUSIONS: S100A4 is a direct beta-catenin/TCF target, induces migration and invasion in vitro and metastasis in vivo, and has value for prognosis of metastasis formation in colon cancer patients.
Cell Movement↗
Ductoscopy and intraductal vacuum assisted biopsy in women with pathologic nipple discharge.
BACKGROUND: Fiberoptic ductoscopy is increasingly used to evaluate pathologic nipple discharge. A major limitation of this technique is the inability to obtain tissue samples from suspicious intraductal lesions. We present a novel technique for ductoscopic biopsy of intraluminal tumors. METHODS: From 2002 to 2005 ductoscopy was performed in 38 women with nipple discharge using a rigid gradient index microendoscope (diameter 0.7 mm) and a special needle for intraductal vacuum assisted biopsy. Results of preoperative biopsy were correlated with the histology of the resection specimen RESULTS: Cannulation of the discharging duct was successful in 37 of 38 patients (97%). Intraductal lesions were diagnosed in 29 women (78%). The sensitivity of ductoscopy and galactography in the detection of intraductal lesion was comparable (96% vs. 89%). Ductoscopic biopsy of intraductal lesions was technically successful in all but one case. Generally, the quality of the biopsy samples was good. Diagnostic biopsy samples were obtained in 26 of 28 patients (93%). Two samples contained necrosis and were considered to be non-representative. Histological analysis of the biopsy specimens showed 22 papilloma, 2 in situ carcinoma and 2 invasive carcinoma. Histology of the resection specimens confirmed the diagnosis in all cases, but there was one case with additional carcinoma lobulare in situ. CONCLUSIONS: Ductoscopic vacuum assisted biopsy is a new technique for tissue sampling of intraductal breast lesions. This method may improve preoperative evaluation of pathologic nipple discharge in selected patients, but it should not be considered as a method for screening of early breast cancer.
Adult↗
Genetic dissection of apoptosis and cell cycle control in response of colorectal cancer treated with preoperative radiochemotherapy.
BACKGROUND: In previous analyses we identified therapy-induced upregulation of the CDK inhibitor p21CIP/WAF-1 and consequently decreased tumor cell proliferation or loss of Bax as adverse factors for survival in rectal cancer treated with radiochemotherapy. Here, we address the individual role of p53 and its transcriptional targets, p21CIP/WAF-1 and Bax, on apoptosis induced by individual components of multimodal anticancer therapy, i.e. 5-fluorouracil (5-FU), ionising gamma-radiation (IR) and heat shock/hyperthermia. METHODS: We analysed tumor samples 66 patients with rectal carcinoma treated by a neoadjuvant approach with radiochemotherapy +/- heat shock/hyperthermia for the expression and mutation of p53 and the expression of p21CIP/WAF-1 and Bax. These data were correlated with the tumor response. The functional relevance of p53, p21CIP/WAF-1 and Bax was investigated in isogeneic HCT116 cell mutants treated with 5-FU, IR and heat shock. RESULTS: Rectal carcinoma patients who received an optimal heat shock treatment showed a response that correlated well with Bax expression (p = 0.018). Local tumor response in the whole cohort was linked to expression of p21CIP/WAF-1 (p < 0.05), but not p53 expression or mutation. This dichotomy of p53 pathway components regulating response to therapy was confirmed in vitro. In isogeneic HCT116 cell mutants, loss of Bax but not p53 or p21CIP/WAF-1 resulted in resistance against heat shock. In contrast, loss of p21CIP/WAF-1 or, to a lesser extent, p53 sensitized predominantly for 5-FU and IR. CONCLUSION: These data establish a different impact of p53 pathway components on treatment responses. While chemotherapy and IR depend primarily on cell cycle control and p21, heat shock depends primarily on Bax. In contrast, p53 status poorly correlates with response. These analyses therefore provide a rational approach for dissecting the mode of action of single treatment modalities that may be employed to circumvent clinically relevant resistance mechanisms in rectal cancer.
Antimetabolites, Antineoplastic↗
Long-term morbidity of patients with early breast cancer after sentinel lymph node biopsy compared to axillary lymph node dissection.
BACKGROUND AND OBJECTIVES: Sentinel lymph node biopsy (SLNB) is widely accepted as an excellent method in the management of early breast cancer in patients with clinically negative axillary lymph nodes. Since SLNB requires less traumatic surgery to the axilla than axillary lymph node dissection (ALND), it was assumed to result in reduced shoulder/arm morbidity. However, data on long-term morbidity after SNLB are sparse. The present study was set up to compare long-term arm/shoulder morbidity as well as oncological outcome after SLNB versus ALND in patients with early breast cancer. METHODS: Oncological outcome, objective shoulder/arm morbidity, and subjective complaints after SLNB or ALND for T1 breast cancer were assessed after a minimum follow-up of 20 months. RESULTS: One hundred thirty four patients were included in the study. Thirty-one patients underwent SNLB only, 103 patients had SLNB followed by ALND or ALND only. Loss of strength and hypaesthesia were less frequent after SLNB. No lymph oedema occurred after SNLB without adjuvant radiotherapy. Subjective complaints concerning pain, hypaesthesia, and paresthesia were more common in the ALND group. No axillary recurrence developed in either group. CONCLUSIONS: Isolated SLNB in node-negative pT1 breast cancer patients is a highly efficient tool to reduce postoperative long-term morbidity without compromising the local control of the disease. The reported ameliorations should favour SLNB as staging and treatment modality in patients suffering from early breast cancer.
Adult↗
Correlation of visinin-like-protein-1 expression with clinicopathological features in squamous cell carcinoma of the esophagus.
EF-hand Ca(2+)-sensor proteins are key molecules for transducing Ca(2+) signals into physiological answers and changes in cytosolic Ca(2+) concentration control a variety of cellular responses, including proliferation, migration, and differentiation, which are relevant for tumor progression. The Ca(2+)-sensor visinin-like protein-1 (VILIP-1) has recently attracted major interest due to its putative tumor suppressor function. Whereas VILIP-1 is expressed in normal skin, it is downregulated in skin tumors in a murine tumor model. The aim of this study was to investigate the expression of the Ca(2+)-sensor VILIP-1 in squamous cell carcinoma of the esophagus and to correlate expression levels with clinicopathological features of the tumor. We examined VILIP-1 expression in 54 specimens of esophageal squamous cell carcinomas and 24 normal esophagus tissues, with immunohistochemical staining and immunofluorescence co-staining techniques. VILIP-1 expression was completely lost or significantly reduced in esophageal tumor tissue compared with normal squamous epithelium. Correlation with clinicopathological features indicated that there was significantly less VILIP-1 expression in lymph node positive (N = 1) versus lymph node negative (N = 0) tumors (P = 0.002). Although there was no significant difference between highly (G(1)), moderately (G(2)) and poorly differentiated (G(3)) tumors (P = 0.177), VILIP-1 expression in tumors is significantly correlated with the depth of tumor invasion (P = 0.028 between T1, T2, T3, and T4). In contrast, co-staining with the proliferation marker Ki-67 indicated no significant correlation with proliferation rates in tumors (Ki-67 index of the tumor). In summary, the expression of the Ca(2+)-sensor VILIP-1 was found to be lost during development of squamous cell carcinoma of the esophagus. The protein expression level significantly correlates with invasive features, such as depth of tumor invasion and local lymph node metastasis, but not with proliferation rate of tumor cells.
Aged↗
Gastric cancer surgery in elderly patients.
BACKGROUND: To investigate the value of individual risk-adapted therapy in geriatric patients, we performed a consecutive analysis of 363 patients undergoing potentially curative surgery for gastric cancer. PATIENTS AND METHODS: All patients underwent extensive preoperative workup to assess surgical risk. The following criteria were evaluated in 3 age groups (<60 years, 60-75 years, and >75 years): comorbidity, tumor characteristics, type of resection, postoperative morbidity and mortality, recurrence rate, overall survival, and disease-free survival. RESULTS: There was an increased rate of comorbidity in the higher age groups (51% vs 76% vs 83%; P<0.05). Cardiovascular and pulmonary diseases were most common. There was a decrease in the rate of both total gastrectomy (74%, 54%, 46%; P<0.05) and D2 lymphadenectomy (78%, 53%, 31%; P<0.05). The 30-day mortality in the 3 age groups was 0%, 1%, and 8%, respectively (P<0.05). There was only a slight difference in tumor recurrence rate (35%, 37%, and 27%; P=0.437), with no significant difference in 5-year cancer-related survival (61%, 53%, 61%; P=0.199). CONCLUSIONS: Patient selection and risk-adapted surgery in elderly patients can result in acceptable therapeutic results comparable to younger patients. Limited surgery in elderly gastric cancer patients with high comorbidity does not necessarily compromise oncological outcome.
Age Factors↗
Intraoperative ductoscopy in women undergoing surgery for breast cancer.
BACKGROUND: Extensive intraductal disease represents an important clinical problem in the management of patients with invasive or in situ breast cancer. The purpose of this study was to determine the value of intraoperative ductoscopy for detection of intraductal neoplasia in women with breast cancer. METHODS: Intraoperative ductoscopy was performed in 54 women undergoing operation for breast cancer. A rigid gradient index microendoscope (0.7 mm) was used for all examinations. Ductoscopy findings were documented prospectively and correlated with preoperative mammography and histology of the resection specimen. RESULTS: Fifty of 54 (92%) patients were examined successfully. Ductoscopy identified intraductal lesions (ie, red patches, ductal obstruction, or microcalcifications) in 25 of 50 (50%) patients. Abnormal ductoscopic appearance was found in 19 of 23 patients with extensive intraductal disease (82%). Mammographic microcalcifications were observed in 15 of those 19 patients and in 3 patients with normal ductoscopy (78%). The combined sensitivity of both methods was 95%. Patients with an abnormal ductal appearance on ductoscopy, compared with those with a normal ductal appearance, had a greater incidence of extensive intraductal spread of cancer (76% vs 16%) and a greater incidence of positive surgical margins (44% vs 12%). CONCLUSIONS: High-resolution ductoscopy is able to detect extensive intraductal disease in a considerable number of women with breast cancer. In selected patients, a combination of both preoperative imaging and intraoperative ductoscopy may help to avoid incomplete resections and re-excisions.
Adult↗
Pre- and postoperative cytokine release after in vitro whole blood lipopolysaccharide stimulation and frequent toll-like receptor 4 polymorphisms.
In a prospective cohort study, we examined 62 patients undergoing major surgical cancer therapy for Toll-like receptor 4 (TLR4) gene polymorphisms (Asp299Gly and Thr399Ile) and their influence on cytokine levels pre- and postoperatively, as well as cytokine levels after whole blood lipopolysaccharide (LPS) stimulation. Incidence of the TLR4 gene single nucleotide polymorphism (SNP) Asp299Gly/Thr399Ile was 14.5% (9/62). Overall, mortality was unaffected by the TLR4 SNP. Preoperative cytokine levels were low, with most of the values of cytokines being below the detection levels. After preoperative stimulation of whole blood with 50 pg/mL LPS, TNF-alpha and IL-6 values increased significantly in both groups. However, no significant influence was detectable between the TLR4 SNP group and the wild type group (WT group). Postoperative IL-6 levels, but not TNF-alpha levels, were significantly increased in both groups. Postoperative LPS stimulation resulted in significantly lower TNF-alpha levels compared with preoperative induction, with a more than 2.3-fold decrease in the TLR4 SNP group: 310.83 pg/mL (SD: 117.53) to 134.08 pg/mL (SD: 91.49; P < 0.001) and a 2.2-fold decrease in the WT group: 422.97 pg/mL (SD: 662.57) to 191.68 pg/mL (SD:147.26; P = 0.031). IL-6 levels after stimulation were comparably decreased with similarly no significant difference between the two groups. We conclude that the TLR4 polymorphism Asp299Gly/Thr399Ile has no influence on cytokine release after LPS stimulation in the early and late course after major surgery. The LPS adaptation effect of cytokine release after surgery is furthermore not affected by the presence of the TLR4 polymorphism Asp299Gly/Thr399Ile.
Amino Acid Substitution↗
Virtual hospital and digital medicine--why is the GRID needed?
The promise of telemedicine to enable equal access to high-level medical care can only be realised by the development of virtual hospitals, digital medicine and a bridging of the digital divide between the various regions of the world. For this, the concept of the Grid should be integrated with other communication networks and platforms. A promising approach is the implementation of service-oriented architectures for an invisible grid, hiding complexity for both application developers and end-users. Therefore integrated Grid Tools Suites for application programmers must be developed. Thus enhancing development and deployment of Grid applications can bring us closer to the simplicity of use that is desired for grid infrastructures not only within the medico-clinical field.
Databases as Topic↗
New trends in the virtualization of hospitals--tools for global e-Health.
The development of virtual hospitals and digital medicine helps to bridge the digital divide between different regions of the world and enables equal access to high-level medical care. Pre-operative planning, intra-operative navigation and minimally-invasive surgery require a digital and virtual environment supporting the perception of the physician. As data and computing resources in a virtual hospital are distributed over many sites the concept of the Grid should be integrated with other communication networks and platforms. A promising approach is the implementation of service-oriented architectures for an invisible grid, hiding complexity for both application developers and end-users. Examples of promising medical applications of Grid technology are the real-time 3D-visualization and manipulation of patient data for individualized treatment planning and the creation of distributed intelligent databases of medical images.
Artificial Intelligence↗
Vascular endothelial growth factor-D and its receptor VEGFR-3: two novel independent prognostic markers in gastric adenocarcinoma.
PURPOSE: Vascular endothelial growth factor (VEGF)-D and its homolog VEGF-C influence lymphangiogenesis through activation of VEGF receptor 3 (VEGFR-3), and have been implicated in lymphatic tumor spread. Nodal dissemination of gastric adenocarcinomas critically determines clinical outcome and therapeutic options of affected patients. Therefore, we analyzed expression and prognostic significance of VEGF-D along with VEGF-C, and VEGFR-3 in gastric adenocarcinomas. MATERIALS AND METHODS: VEGF-C, VEGF-D, and VEGFR-3 were analyzed in 91 R(0)-resected primary gastric adenocarcinomas, corresponding noncancerous gastric mucosa, and lymph node metastases employing immunohistochemistry and/or in situ hybridization. Blood and lymph vessel densities were assessed after staining with CD31 and LYVE-1-specific antibodies. RESULTS: VEGF-D and VEGF-C were detected in 67.0% and 50.5% of gastric cancers, respectively. Healthy gastric mucosa was negative for VEGF-C and in 12.5% positive for VEGF-D. Presence of VEGF-D (P = .005) or VEGF-C (P = .006) was correlated with lymphatic metastases and decreased survival (VEGF-D, P < .05; VEGF-C, P < .05). VEGFR-3 was correlated with reduced carcinoma-specific survival (P < .05), and Cox multivariate regression analysis qualified VEGF-D and VEGFR-3, but not VEGF-C, as independent prognostic parameters. In lymph node-positive gastric cancers, presence of VEGF-D/VEGFR-3 was associated with poor survival, whereas absence of VEGF-D/VEGFR-3 defined a subgroup of patients with clearly favorable prognosis. CONCLUSION: VEGF-D and VEGFR-3 are novel independent prognostic marker molecules aiding to identify patients with poor prognosis after curative resection of gastric adenocarcinomas. Combined analysis of the VEGF-C/VEGF-D/VEGFR-3 system can be useful to identify patients with unfavorable clinical outcome and thereby may help to refine therapeutic decisions in gastric cancer.
Adenocarcinoma↗
Nonviral jet-injection gene transfer for efficient in vivo cytosine deaminase suicide gene therapy of colon carcinoma.
Jet-injection technology has developed into an efficient gene delivery system for nonviral in vivo gene transfer. In this study the jet-injector system was used for the intratumoral gene transfer of small volumes of naked DNA encoding the Escherichia coli cytosine deaminase (CD) suicide gene. In our in vivo studies human colon carcinoma (patient-derived tumor model Colo5734 and SW480 colon carcinoma)-bearing NMRI-nu/nu male mice received four jet injections (10 microl per injection) of the CD-gene-carrying plasmid, representing 40 microg plasmid DNA per animal. Forty-eight hours after jet-injection, treatment of tumors with 5-fluorocytosine (5-FC; 500 mg/kg ip) was started and during treatment tumor volumes were measured. Starting from day 5 of 5-FC treatment inhibition of tumor growth was seen in the CD-gene-transduced tumors compared to the respective control groups, which lasted for the entire observation time. Expression analysis at the mRNA and protein levels revealed efficient expression of the CD gene in the jet-injected tumors. Therefore, in this in vivo study jet-injection gene transfer of 40 microg CD-expressing naked plasmid DNA leads to a significant tumor growth inhibition. This study demonstrates the applicability of the jet-injection technology for in vivo gene transfer into tumors to achieve efficient tumor gene therapy.
Animals↗
YB-1 facilitates basal and 5-fluorouracil-inducible expression of the human major vault protein (MVP) gene.
Vaults have been suggested to play a direct role in multidrug resistance (MDR) to anticancer drugs. The human major vault protein (MVP) also known as lung resistance-related protein (LRP) represents the predominant component of vaults that may be involved in the defense against xenobiotics. Here, we demonstrate that besides MDR-related cytostatics, also the non-MDR-related drug 5-fluorouracil (5-FU) was able to induce MVP mRNA and protein expression. Treatment with 5-FU amplified the binding activity and interaction of the transcription factor Y-box binding protein-1 (YB-1) with the Y-box of the human MVP gene promoter in a time-dependent manner. 5-FU also induced reporter expressions driven by a panel of newly generated MVP promoter deletion mutants. Interestingly, stably YB-1 overexpressing cell clones showed enhanced binding of YB-1 to the Y-box motif, associated with enhanced basal as well as 5-FU-inducible MVP promoter-driven reporter expressions. Moreover, transduction of YB-1 cDNA led to increased expression of endogenous MVP protein. Under physiological conditions, we observed a strong coexpression of MVP and YB-1 in human colon carcinoma specimen. In summary, our data demonstrate a direct involvement of YB-1 in controlling basal and 5-FU-induced MVP promoter activity. Therefore, YB-1 is directly linked to MVP-mediated drug resistance.
Antimetabolites, Antineoplastic↗
Time-domain scanning optical mammography: I. Recording and assessment of mammograms of 154 patients.
Using a triple wavelength (670 nm, 785 nm, 843/884 nm) scanning laser-pulse mammograph we recorded craniocaudal and mediolateral projection optical mammograms of 154 patients, suspected of having breast cancer. From distributions of times of flight of photons recorded at typically 1000-2000 scan positions, optical mammograms were derived displaying (inverse) photon counts in selected time windows, absorption and reduced scattering coefficients or total haemoglobin concentration and blood oxygen saturation. Optical mammograms were analysed by comparing them with x-ray and MR mammograms, including results of histopathology, attributing a subjective visibility score to each tumour assessed. Out of 102 histologically confirmed tumours, 72 tumours were detected retrospectively in both optical projection mammograms, in addition 20 cases in one projection only, whereas 10 tumours were not detectable in any projection. Tumour contrast and contrast-to-noise ratios of mammograms of the same breast, but derived from measured DTOFs by various methods were quantitatively compared. On average, inverse photon counts in selected time windows, including total photon counts, provide highest tumour contrast and contrast-to-noise ratios. Based on the results of the present study we developed a multi-wavelength, multi-projection scanning time-domain optical mammograph with improved spectral and spatial (angular) sampling, that allows us to record entire mammograms simultaneously at various offsets between the transmitting fibre and receiving fibre bundle and provides first results for illustration.
Breast Neoplasms↗
Time-domain scanning optical mammography: II. Optical properties and tissue parameters of 87 carcinomas.
Within a clinical trial on scanning time-domain optical mammography reported on in a companion publication (part I), craniocaudal and mediolateral projection optical mammograms were recorded from 154 patients, suspected of having breast cancer. Here we report on in vivo optical properties of the subset of 87 histologically validated carcinomas which were visible in optical mammograms recorded at two or three near-infrared wavelengths. Tumour absorption and reduced scattering coefficients were derived from distributions of times of flight of photons recorded at the tumour site employing the model of diffraction of photon density waves by a spherical inhomogeneity, located in an otherwise homogeneous tissue slab. Effective tumour radii, taken from pathology, and tumour location along the compression direction, deduced from off-axis optical scans of the tumour region, were included in the analysis as prior knowledge, if available. On average, tumour absorption coefficients exceeded those of surrounding healthy breast tissue by a factor of about 2.5 (670 nm), whereas tumour reduced scattering coefficients were larger by about 20% (670 nm). From absorption coefficients at 670 nm and 785 nm total haemoglobin concentration and blood oxygen saturation were deduced for tumours and surrounding healthy breast tissue. Apart from a few outliers total haemoglobin concentration was observed to be systematically larger in tumours compared to healthy breast tissue. In contrast, blood oxygen saturation was found to be a poor discriminator for tumours and healthy breast tissue; both median values of blood oxygen saturation are the same within their statistical uncertainties. However, the ratio of total haemoglobin concentration over blood oxygen saturation further improves discrimination between tumours and healthy breast tissue. For 29 tumours detected in optical mammograms recorded at three wavelengths (670 nm, 785 nm, 843 nm or 884 nm), scatter power was derived from transport scattering coefficients. Scatter power of tumours tends to be larger than that of surrounding healthy breast tissue, yet the 95% confidence intervals of both medians overlap.
Breast Neoplasms↗
Reconstruction of optical properties of phantom and breast lesion in vivo from paraxial scanning data.
We report on the reconstruction of absorption and reduced scattering coefficients of breast tissue in vivo of a patient with mastopathic disease. Distributions of times of flight of photons through the compressed breast were recorded by paraxial scanning. From data measured at four different source-detector offsets optical properties were reconstructed within the linear Rytov approximation by a fast inverse Fourier space method. Low-pass filtering in Fourier space was employed to remove excessive noise from high spatial frequency components and to reduce the computational efforts by a factor of 3, typically. The mammograms displaying reconstructed absorption and reduced scattering coefficients were compared with projection mammograms either obtained by time-window analysis of experimental data or based on average absorption and reduced scattering coefficients which were derived from measured temporal point spread functions within a simple homogeneous model. All inhomogeneities which were visible in the projection mammograms and which could be associated with specific breast tissue compartments could be correlated with inhomogeneities in the reconstructed absorption coefficient. In particular, the mastopathic disease was detected in the reconstructed absorption mammogram. In order to assess reliability of optical properties reconstructed from data obtained by paraxial scanning, corresponding phantom experiments and reconstructions of phantom optical properties were carried out. Because of the limited angular range sampled by the in vivo and phantom measurements, considerable blurring of the absorption coefficient occurs along the compression direction, compromising longitudinal resolution.
Algorithms↗