Registration of phase-contrast images in propagation-based X-ray phase tomography.

X-ray phase tomography aims at reconstructing the 3D electron density distribution of an object. It offers enhanced sensitivity compared to attenuation-based X-ray absorption tomography. In propagation-based methods, phase contrast is achieved by letting the beam propagate after interaction with the object. The phase shift is then retrieved at each projection angle, and subsequently used in tomographic reconstruction to obtain the refractive index decrement distribution, which is proportional to the electron density. Accurate phase retrieval is achieved by combining images at different propagation distances. For reconstructions of good quality, the phase-contrast images recorded at different distances need to be accurately aligned. In this work, we characterise the artefacts related to misalignment of the phase-contrast images, and investigate the use of different registration algorithms for aligning in-line phase-contrast images. The characterisation of artefacts is done by a simulation study and comparison with experimental data. Loss in resolution due to vibrations is found to be comparable to attenuation-based computed tomography. Further, it is shown that registration of phase-contrast images is nontrivial due to the difference in contrast between the different images, and the often periodical artefacts present in the phase-contrast images if multilayer X-ray optics are used. To address this, we compared two registration algorithms for aligning phase-contrast images acquired by magnified X-ray nanotomography: one based on cross-correlation and one based on mutual information. We found that the mutual information-based registration algorithm was more robust than a correlation-based method.

[Computer-assisted diagnostic procedure for multislice computed tomography for assessment of the pulmonary arterial circulation. Clinical relevance]. / Computerassistiertes Diagnoseverfahren für die Mehrschichtcomputertomographie zur Beurteilung der pulmonalarteriellen Strombahn. Klinische Bedeutung.

BACKGROUND: A recently developed CAD software which highlights intravascular thrombotic structures from multislice computed tomography (MSCT) data was tested regarding feasibility, interobserver reliability and effect on radiology reports. MATERIAL AND METHODS: The CAD system ImageChecker® CT-Lung was tested in a randomized double-blinded study on 160 MSCT datasets (standardized technical conditions) performed for suspected pulmonary embolism (PE). The CAD data and images were analyzed by three radiologists in an independent and blinded fashion. RESULTS: The data from all 160 cases could be analyzed and 604 CAD prompts were set. Using the CAD analysis significantly more PEs were found in the peripheral pulmonary arterial circulation than described in the initial report. In 38 cases the 3 radiologists in consensus scored the images with the CAD adjunct as PE positive in peripheral vessels, which were initially reported as negative. Despite differences in the evaluation between two radiologists the amended assessment of the imaging data using the CAD softwear was reliable. There was a significant correlation between D-dimer values and the number of embolic structures detected by the CAD analysis. CONCLUSION: The recently developed CAD system is a useful adjunct as second reader to detect subtle emboli in peripheral vessels of MSCT datasets.

Renal ablation in patients with end-stage renal disease.

BACKGROUND: Transarterial catheter embolization of the kidneys (TAE) is a minimally invasive, image-guided procedure. In this study outcome and TAE-related complications of the patients who underwent TAE of the kidneys were evaluated retrospectively. PATIENTS AND METHODS: Between August 2003 and August 2009, 11 patients underwent selective percutaneous transarterial renal embolization for end stage renal disease associated with uncontrolled hypertension, nephrotic syndrome, bleeding or malignancy. TAE of renal arteries was performed using different embolization agents. RESULTS: Successful renal embolization was possible in all 21 kidneys. All patients became anuric. Non-target embolization was not detectable. Nevertheless, all patients developed some degree of postembolization symptoms including nausea, vomiting, fever or pain. A typical finding after embolization was an increase in the C-reactive protein. CONCLUSIONS: Renal embolization is rarely done but should be considered as an alternative to surgical nephrectomy in patients with end stage renal disease due to the lesser invasiveness. Our study confirms the safety and effectivity of percutaneous renal embolization in patients with ESRD. We were able to control the hypertension, nephrotic syndrome, and bleeding caused by ESRD.

Transarterial catheter embolization of a sarcoma for preoperative conditioning.

This paper presents a case of an undifferentiated pleomorphic sarcoma/NOS (not otherwise specified; former pleomorphic - storiform malignant fibrous histiocytoma) of the lower leg, of a huge tumor causing ulceration of the cutaneous surface. To improve preoperative conditions, selective transarterial devascularization of the tumor feeders was performed. At operation the tumor was completely ischaemic allowing for clear tumor demarcation with little blood loss during surgery.

[Diagnostic pitfalls with Cushing's syndrome]. / Diagnostische Fallstricke beim Cushing-Syndrom.

Adrenal cortical carcinoma is a rare diagnosis and may present with hormone secretion. A histological differentiation between an adrenal cortical adenoma and carcinoma can be very difficult. However, a fast diagnosis including staging and complete surgical resection is pivotal for the prognosis of an adrenal cortical carcinoma. Metastasing adrenal cortical carcinoma should be treated with a mitotane based chemotherapy, and inclusion in the "firm-act study" is highly recommended. The present case report demonstrates the diagnostic pitfalls in a female patients with Cushing's syndrome who suffered from metastasing adrenal cortical carcinoma.

Effects of long-term immobilisation on cortical bone mass after traumatic amputation of the phalanges estimated by digital X-ray radiogrammetry.

UNLABELLED: Osteopenia of the cortical and trabecular bone partition is a common finding after immobilisation. Digital X-ray radiogrammetry (DXR) seems to quantify cortical demineralisation caused by circular saw amputation already few days after accident. INTRODUCTION: The study analyses the extent of demineralisation caused by immobilisation in patients with digital amputation after a circular saw injury, and elucidates the period of time which discloses a significant deprivation of bone mineral density estimated at the metacarpalia II-IV using DXR. METHODS: Twenty-eight patients with digital amputations underwent measurements of bone mineral density, cortical thickness, bone width and metacarpal index using DXR-technology in a follow-up up to 902 days. RESULTS: The data showed a significant decline of bone mineral density (-10.47%), the metacarpal index (-4.38%), the bone width (-12.06%) and the cortical thickness (-7.04%) after trauma-related amputation. The cortical demineralisation of the metacarpals could already be revealed in two patients after the second day, according to the amputation of phalanges (-3.65%). CONCLUSIONS: The inhibition of the periosteal bone formation detected by DXR-technique seems to be a specific finding caused by amputation, which thus differs from normal age-related (i.e., endosteal) bone loss and from demineralisation following acute immobilisation (i.e., trabecular osteopenia).

31P-MR spectroscopic imaging in hypertensive heart disease.

Hypertensive heart disease (HHD) causes structural changes (e.g., fibrosis) that result in diastolic and systolic myocardial dysfunction. Alterations of (31)P metabolism and cardiac energy impairments were assessed in patients with HHD by MR spectroscopy (MRS) and correlated with left ventricular systolic function. Thirty-six patients with HHD and 20 healthy controls (mean age 35.2+/-10.7 years) were examined with (31)P-MRS at 1.5 T by using an ECG-gated CSI sequence. Twenty-five patients (mean age 64.3+/-9.3 years) had diastolic dysfunction, but preserved systolic function (HHD-D), whereas 11 patients (62.3+/-11.4 years) suffered from additional impaired systolic function (HHD-S). In both patient groups, the PCr/gamma-ATP ratio was lower than in the controls (controls: 2.07+/-0.17; P<0.001), and in HHD-S was lower than in HHD-D (1.43+/-0.21 vs. 1.65+/-0.25; P=0.012). PCr/gamma-ATP ratios were linearly correlated with LVEF (Pearson's r: 0.39; P=0.025). In the HHD-S group, the PDE/gamma-ATP ratio was significantly lower (0.56+/-0.36) than in the controls (1.14+/-0.42; P=0.001). In contrast to the group of HHD-D patients, whose slightly decreased PCr/gamma-ATP ratios compared to controls may be explained by age differences, the more distinct changes observed in HHD-S patients indicate an altered energy metabolism. The observed metabolic changes were related to functional impairments, as indicated by a reduced LVEF. Reduced PDE/ATP ratios indicate changes in the phospholipid metabolism.

Digital radiogrammetry as a new diagnostic tool for estimation of disease-related osteoporosis in rheumatoid arthritis compared with pQCT.

OBJECTIVES: To investigate the potential of a new osteogeometric technology based on digital X-ray radiogrammetry (DXR) as a diagnostic tool for quantification of severity-dependent osteoporosis, and to distinguish between inflammation-mediated and corticoid-induced variations of bone mineralisation in patients suffering from rheumatoid arthritis. METHODS: Ninety-six patients (duration of disease: <18 months) underwent retrospective calculations of bone mineral density (DXR-BMD) and metacarpal index (MCI) by DXR, which were calculated from plain radiographs of the non-dominant hand. For comparison, pQCT-calculated BMD (total, cortical-subcortical and trabecular partition of bone tissue) was done on the distal radius. Severity was classified using Ratingen Score by two independent radiologists, and divided into three main groups. In addition, the patients were separated into those with corticoid medication (n=44; 5 mg/day over a half year period) and a control group (n=52) without any corticoid therapy. RESULTS: Correlations between DXR-BMD and MCI versus pQCT parameters were all significant (0.36

[Influence of body constitution on bone mineral density measured by digital radiogrammetry]. / Einfluss der Körperkonstitution auf die mittels digitaler Radiogrammetrie evaluierte Knochenmineraldichte.

PURPOSE: In addition to many established osteodensitometric techniques, digital radiogrammetry (DXR) is considered to be a reliable method for measuring the cortical bone mineral density (DXR-BMD). This study investigates the influence of body constitution on BMD of healthy adults as calculated by DXR. MATERIALS AND METHODS: In a prospective study, 246 adults without bone affecting diseases in their clinical history underwent DXR for analysis and calculations of bone mineral density and determination of metacarpal index (MCI) and porosity index (PI). Height, weight and body mass index (BMI) were recorded for each patient. RESULTS: For all individuals and for all BMI subgroups, both height (0.55 < R < 0.70, p < 0.01) and body weight (0.56 < R < 0.78, p < 0.01) correlated closely with DXR-BMD. Only in the over-weight group, no significant correlation was found between body weight and DXR-BMD. In addition, a significant reduction of the relative DXR-BMD and MCI values was observed between the over-weight and the under-weight group as well as between normal-weight and under-weight individuals (p < 0.01). Otherwise, cortical porosity decreased with increasing body weight. CONCLUSION: Similar to Dual Energy X-ray Absorptiometry-based studies (DXA), digital radiogrammetry measures an increase in BMD with increasing body weight. Therefore DXR, which provides a precise technique without influence of soft tissue, seems to be a promising technique for quantifying marginal alterations in cortical BMD as well for following the course of osteoporosis.

Noninvasive measurements of cardiac high-energy phosphate metabolites in dilated cardiomyopathy by using 31P spectroscopic chemical shift imaging.

Dilated cardiomyopathy (DCM) is accompanied by an impaired cardiac energy metabolism. The aim of this study was to investigate metabolic ratios in patients with DCM compared to controls by using spectroscopic two-dimensional chemical shift imaging (2D-CSI). Twenty volunteers and 15 patients with severe symptoms (left ventricular ejection fraction, LVEF<30%) and ten patients with moderate symptoms (LVEF>30%) of DCM were investigated. Cardiac 31P MR 2D-CSI measurements (voxel size: 40x40x100 mm3) were performed with a 1.5 T whole-body scanner. Measurement time ranged from 15 min to 30 min. Peak areas and ratios of different metabolites were evaluated, including high-energy phosphates (PCr, ATP), 2,3-diphosphoglycerate (2,3-DPG) and phosphodiesters (PDE). In addition, we evaluated how PCr/ATP ratios correlate with LVEF as an established prognostic factor of heart failure. The PCr/gamma-ATP ratio was significantly decreased in patients with moderate and severe DCM and showed a linear correlation with reduced LVEFs. PDE/ATP ratios were significantly increased only in patients with severe DCM as compared to volunteers. Applying 31P MRS with commonly-available 2D-CSI sequences is a valuable technique to evaluate DCM by determining PCr/ATP ratios noninvasively. In addition to reduced PCr/ATP ratios observed in patients suffering from DCM, significantly-increased PDE/ATP ratios were found in patients with severe DCM.

[Clinical trial for differentiation between corticoid-induced osteoporosis and periarticular demineralization via digital radiogrammetry in patients suffering from rheumatoid arthritis]. / Versuch der Differenzierung zwischen kortikoidinduzierter Osteopenie und periartikulärer Demineralisation mit Hilfe der Digitalen Radiogrammetrie (DXR) bei Patienten mit rheumatoider Arthritis.

PURPOSE: To investigate a new bone densitometric technology based on digital radiogrammetry (DXR) with respect to its ability to measure severity-dependent variations of bone mineral density (BMD) in patients with rheumatoid arthritis and to differentiate between corticoid-induced and periarticular bone mineral density loss. PATIENTS AND METHODS: A total of 153 randomly selected patients suffering from verified rheumatoid arthritis underwent digitally performed plain radiographs of the non-dominant hand and also measurements of dual-energy X-ray absorptiometry (DXA) regarding total femur and lumbar spine in 102 patients and peripheral quantitative computed tomography (pQCT) regarding the distal radius in 51 patients. Using DXR the radiographs of the non-dominant hand were analyzed for cortical bone mineral density calculation. The severity was classified in the DXA group using the Ratingen score. Furthermore, both study populations were divided into patients with and without corticoid therapy. RESULTS: Correlations between BMD determined by DXR and by DXA (R=0.44 for lumbar spine and R=0.61 for total femur) versus pQCT (0.46

The impact of technical conditions of X-ray imaging on reproducibility and precision of digital computer-assisted X-ray radiogrammetry (DXR).

OBJECTIVE: To evaluate the reproducibility of imaging and analysis for bone mineral density (BMD) determination using digital computer-assisted X-ray radiogrammetry (DXR; Pronosco X-posure, version V.2, Sectra Pronosco, Denmark); to verify potential factors that influence BMD extrapolation such as tube voltage, film-focus distance (FFD), film quality and brand (Kodak T-MAT-Plus, Konika SRH, Agfa Scopix), imaging technology (conventional, digital), imaging system (Kodak, Agfa) and exposure level (mAs); and to clarify whether DXR analysis based on printouts of digital images is comparable to analysis of conventional images. DESIGN AND PATIENTS: The hand of a cadaver was X-rayed using varied parameters: 4-8 mAs, 40-52 kV, 90-130 cm FFD. Radiographs under standardised conditions were performed 10 times using a conventional machine (Philips Super 80 CP) and the printouts of a digital system (Digital Diagnost Philips Optimus) for the analysis of reproducibility. One image was scanned and analysed 10 times additionally for imaging reproducibility. RESULTS: Reliability error of the system for the imaging process using conventional radiographs-rays was 0.49% (standard conditions: 6 mAs, 40 kV, 1 m FFD), using printouts of digital images was 2.89% (4 mAs, 42 kV, 1 m FFD) and regarding the analysis process was 0.22%. BMD calculation is not affected by alterations in FFD (precision error 1.21%), mAs (0.83%) or film quality/brand (0.38%), but differs significantly depending on tube voltage (2.70%). The system was not able to analyse conventional images with tube voltages of 49/52 kV. CONCLUSION: DXR technology is stable with most of the tested parameters. Normative data should exclusively be used for calculations using similar tube voltage or correction factors. All other parameters had no significant influence on the BMD calculation. Reproducibility is high. For technical reasons it is not recommended to use the printouts of digital images for BMD determination.

[Evaluation of the primary diagnosis with a CAD-system in mammography]. / Evaluation der Primärbefundung durch ein CAD-System in der Mammadiagnostik.

PURPOSE: To assess the capability of the computer assisted detection (CAD) system to classify calcifications that are histologically verified as malignant and benign or are proven benign by magnification and follow up mammography. MATERIALS AND METHODS: Three groups of microcalcifications (MC) with and without associated masses were enrolled in the study. The cancer group included 141 screen-detected breast cancer cases. One benign group comprised 109 cases with histologically benign specimens obtained through a minimally invasive breast biopsy. A second benign group included 72 lesions with MC that appeared benign on magnification/compression views and were confirmed to be benign on follow-up mammograms over a period of at least 1.5 years. All mammograms were evaluated with a CAD system (Second Look version 3.5, CADx Medical Systems, Canada). RESULTS: CAD correctly detected 125 of 141 (89 %) cancer cases. Of the 16 false negative cases, CAD marked the location of the MC (which were associated with malignant mass) with a mass mark in 12 cases. For benign cases, CAD did not correctly mark the microcalcifications in 59 of the 109 lesions confirmed benign histologically (54.1 %) and in 39 of the 72 lesions established benign mammographically (54.2 %). Adenosis introduced the highest rate of falsely marked microcalcifications (62 %). CONCLUSION: Due to its limited specificity, CAD can still not be recommended for the primary classification of microcalcifications as malignant or benign. Nevertheless, the low false negative rate and rather high detection rate of malignant findings indicate some value of CAD for an independent second reading.

[Quantification of macrophages and granulocytes at the joint cartilage-pannus junction in rheumatoid arthritis]. / Quantifizierung der Makrophagen und Granulozyten an der Gelenkknorpel-Pannus-Grenze bei Rheumatoid-Arthritis.

Rheumatoid-Arthritis (RA) is a systemic disease with chronic joint inflammation caused by complex immune mechanisms. Aim of our study was the analysis of the distributions of macrophages and neutrophils at the cartilage-pannus junction in order to assess the possible functional relationship of both cell types in cartilage damage. We used 39 samples of synovectomies from patients suffering from RA. The samples were stained by histological (Hematoxilin-Eosin, HE), enzymehistological (Naphtol-ASD) and immunohistochemical (Peroxidase-antiperoxidase, alkaline phosphatase-antialkaline phosphatase) techniques and examined by light microscopy. Lysozyme alpha-1-antitrypsin and alpha-1-antichymotrypsin were stained with peroxidase-antiperoxidase-technique, the monoclonal antibody for macrophages CD 68 were used in alkaline phosphatase-antialkaline phosphatase technique. We found a clear domination of macrophages at the cartilage-pannus junction compared to the number of neutrophils. Over 90% of the analyzed cells were identified as macrophages, which were presumably activated macrophages. The macrophages accumulated directly underneath the erosion front and infiltrated the cartilage. The cartilage showed erosions with clear infiltrations by macrophages. We conclude that this distribution is a clear sign of active cartilage destruction by macrophages and emphasize their role in perpetuation of the rheumatoid inflammation.