Biomedical subjects

C D Claussen

Publications and source records attributed to C D Claussen.

At least 55 records · Page 3Linked to original sources

PubMed2005

[A preparation technique for quantitative investigation of SPIO-containing solutions and SPIO-labelled cells by MRI].

UNLABELLED: PURPOSE. This work aims to present a preparation technique for ex-vivo MR examination of SPIO (superparamagnetic iron oxide) containing solutions or SPIO labeled cells. Accumulations of SPIO particles and labeled cells were prepared in different concentrations using agar gel phantoms. Signal extinction around accumulations of magnetic material was examined systematically by gradient echo sequences with variable echo times and spatial resolution. The correlation between local iron concentration and diameter of signal extinction in MR gradient echo images was investigated. METHODS: Resovist, (SHU 555A) was used as superparamagnetic contrast medium. Different concentrations of SPIO-containing solutions (0.75 - 15 mg Fe/10 ml) and magnetically labeled SK-Mel28 cells (25,000-1,000,000 cells/10 ml) were accommodated inside a defined volume in an agar matrix. Diameters of signal void were assessed in dependence on local iron concentration, echo time (5-25 ms) and isotropic spatial resolution (length of voxel 0.25 - 0.60 mm). Measurements were performed on a clinical MR whole body scanner (3 Tesla) using a spoiled gradient echo sequence (FLASH). RESULTS: For the present experimental conditions sensitivity to detect the magnetic label was maximized using TE 25 ms. In contrast, the area of signal cancellation was minimized using TE 5 ms and isotropic resolution of 0.25 mm. In the latter case the image indicated the area of magnetic material most precisely. Diameter of signal cancellation was a logarithmic function on local iron concentration. In the presented set-up detection of concentrations as low as 0.75 mg Fe/10 ml in SPIO-containing solution or 1.25 mg Fe/10 ml in SPIO-labeled SK-Mel28 cells was certainly possible. CONCLUSION: The proposed preparation strategy with a well defined spatial distribution of the magnetic material in an agar gel phantom produced reliable results and appears clearly superior compared to set-ups with randomly distributed material in glass tubes. The diameter of the signal extinction in gradient echo images was significantly affected by the choice of echo time and spatial resolution. The calibration of signal cancellation versus iron concentrations may be valuable to assess SPIO concentrations and possibly numbers of labeled cells under specific conditions in vitro or even in vivo.

Cell Line, Tumor↗

PubMed2005

Low-cost data transfer from a questionnaire to standard software using a barcode pen.

Computer-aided transfer of questionnaire data simplifies the analysis of questionnaires. We present a solution based on an inexpensive barcode pen and its decoder, the software tool Barcode Wizard included in CorelDRAW, and a self-developed application written using Microsoft Visual Basic for Applications. The barcode may be provided on the questionnaire or on a transparency. Error correction is done by means of two different procedures. The present solution can be applied while looking over the completed questionnaire and thus allows time-saving, economic, and precise data transfer from the completed questionnaire directly into computer software.

Computer Peripherals↗

PubMed2005

Drug coated stents for carotid intervention.

Carotid endarterectomy has demonstrated its superiority over medical treatment of symptomatic as well as asymptomatic stenosis of the extracranial carotid artery. Although minimally invasive methods initially failed to produce similar results, stent implantation is becoming an alternative technique for stroke prophylaxis with technical advances, cerebral protection and careful patient selection. Even though restenosis does not seem to be a major limitation compared to coronary interventions, in-stent restenosis might occur more frequently with an increasing number of procedures performed and longer follow-up periods. Drug eluting stents have shown to attenuate this complication. Currently, no clinical data on drug eluting stents in carotid arteries are available. This article discusses the current literature on carotid artery stenting and the potential role of drug eluting stents in this field.

Antineoplastic Agents, Phytogenic↗

PubMed2004

[Radiofrequency ablation of liver metastases].

The liver is the second only to lymph nodes as the most common site of metastatic disease irrespective of the primary tumor. Up to 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improvement of the survival time, only approximately 20% of the patients are eligible for surgical intervention. Radiofrequency (RF) ablation represents one of the most important alternatives as well as complementary methods for the therapy of liver metastases. RF ablation can lead in a selected patient group to a palliation or to an increased life expectancy. RF ablation appears either safer (vs. cryotherapy) or easier (vs. laser) or more effective (percutaneous ethanol instillation [PEI], transarterial chemoembolisation [TACE]) in comparison with other minimal invasive procedures. RF ablation can be performed percutaneously, laparoscopically or intraoperatively and may be combined with chemotherapy as well as with surgical resection. Permanent technical improvements of RF systems, a better understanding of the underlying electrophysiological principles and an interdisciplinary approach will lead to a prognosis improvement in patients with liver metastases.

Catheter Ablation↗

PubMed2004

[Possibilities of whole-body MRI for investigating musculoskeletal diseases].

This contribution outlines possibilities and limitations of whole-body MRI for investigating musculoskeletal diseases. Benefits and drawbacks of the novel whole-body MRI technology are discussed and a possible whole-body MRI sequence protocol for musculoskeletal examinations is proposed. Muscle, joint and bone diseases are discussed in which the application of whole-body MRI may be of advantage. Particularly, polymyositis, muscledystrophy, rheumatoid arthritis, spondylitis ancylosans, multiple trauma, skeletal metastases, multiple myeloma and malignant lymphoma are mentioned. Whole-body MRI opens new advantages for the examination of multifocal musculoskeletal diseases. The clinical benefit of this method for particular diseases has to be evaluated in further studies, however.

Acquired Hyperostosis Syndrome↗

PubMed2004

[Oncologic screening with whole-body MRI: possibilities and limitations].

In the last decade the interest in radiological screening examination increased among informed laymen enormously. Independent from the evidence of whole-body examinations for cancer prevention the discussion about screening must again be considered again due to the newest technical developments, since MRI of the whole-body with high spatial resolution is feasible now within one single examination. The newest system permits simultaneous connection of up to 76 coil elements and signal reception from 32 independent receiving channels. Whole-body MRI including magnetic resonance colonography (MRC) is feasible within 60 min. In this review potential investigation protocols will be presented. Potentials, challenges and limitations of whole-body MRI in the prevention of the malignancies most frequently leading to death are discussed on the basis own experiences examples and the literature.

Aged↗

PubMed2004

Diffusion characteristics of large molecules assessed by proton MRS on a whole-body MR system.

Methods for examinations of diffusion of large molecules of the size of fatty acids or triglycerides were developed for whole body MR units. Samples of aliphatic molecules were examined to study the influence of chain length. Feasibility under in vivo conditions was tested on lard samples at 37 degrees C and on human subjects Three stimulated echo sequences with maximum b-values of 2000 s/mm(2), 20000 s/mm(2), and 80000 s/mm(2) were used to assess a wide range of mobility. Sequence timing was optimized to minimize relaxation losses of fatty tissue. Apparent diffusion coefficients (ADC) were determined from five spectra with different diffusion weighting. In-vitro experiments were performed on butanol, decanol, and oleic acid to study the influence of chain length. In vivo conditions were mimicked using lard at 37 degrees C representing a composition of substances of various chain lengths. Subcutaneous fat and tibial bone marrow were studied in three healthy volunteers. ADC of muscular lipids of the lower leg was determined in two subjects. ADC values of pure aliphatic substances were in the range between 3.2 x 10(-5) mm(2)/s for oleic acid and 37.8 x 10(-5) mm(2)/s for butanol. In vivo investigations revealed ADC values of 1.11-1.24 x 10(-5) mm(2)/s for tibial bone marrow and 1.21-2.05 x 10(-5) mm(2)/s for subcutaneous fat. Diffusion coefficients of extra- and intramyocellular lipids were 1.83-3.65 x 10(-5) mm(2)/s and 2.22-3.60 x 10(-5) mm(2)/s, respectively. The proposed technique enables determination of ADC values of relatively large molecules and of lipid tissue compartments under in vivo conditions. Diffusion properties in several human lipid compartments are reported for the first time. Incoherent voxel motion influences the in vivo results to an unknown degree because of high motion sensitivity. In vitro experiments revealed ADC values depending on the chain length of the substances, indicating a residual dependence of measured ADC's on sequence timing.

1-Butanol↗

PubMed2004

[Chemoembolization of hepatocellular carcinomas: which factors determine therapeutic response and survival?].

PURPOSE: To determine independent prognostic factors influencing the survival of patients with hepatocellular carcinoma (HCC) treated with transcatheter arterial chemoembolization (TACE). MATERIALS AND METHODS: Ninety-one patients with unresectable HCC were treated with 269 repetitive TACE. The dosages of epirubicin (40-60 mg) and ethiodized oil (8-20 ml) were adjusted to tumor size and liver function. The impact of tumor size, macroscopic tumor type, tumor location, portal vein infiltration, capsular infiltration, tumor vascularization, uptake of ethiodized oil within the tumors, Child-Pugh-Class and Okuda-Stage on patient survival were evaluated by means of univariate and multivariate regression analysis. RESULTS: The following independent prognostic factors were found: tumor type (nodular vs. infiltrating, p = 0 008), tumor size (p = 0.01), Child-Pugh-Class (A vs. B; p = 0.02) and grade of tumor vascularization (p = 0.04). In 57 patients with HCC of the nodular type, the median survival time was significant longer than in 32 patients with HCC of the infiltrating type (17.0 months vs. 7.9 months; p < 0.003; 2 tumors could not be classified). The 1-, 2- and 3-year-survival rates were significantly higher in 57 patients with Okuda-Stage I disease, compared to 34 patients with Okuda-Stage II and III disease (73%, 31% and 8% vs. 23%, 6% and 4% p < 0.0001). CONCLUSIONS: Tumor type, tumor size and grade of liver cirrhosis have an independent impact on prognosis of patients with HCC treated by TACE. An appropriate selection of patients is necessary to improve patients survival.

Adult↗

PubMed2004

[Observation and control of hepatic specimens with MRI and MRS].

PURPOSE: The purpose of this study was to observe the process of fixation in liver specimens non-invasively by means of magnetic resonance. The fixation process of several formaldehyde-containing solutions was monitored with MRI and MRS at two different temperatures. MATERIALS AND METHODS: Liver specimens were conserved in aqueous fixative solutions containing formaldehyde concentrations of 0.7, 1.8, 4 and 7.2 % and at different temperatures of 5 degrees C and 20 degrees C. MRI was performed with T1-, T2- and PD-weighted TSE sequences, a 2D FLASH-sequence with and without magnetization transfer, and a FISP 3D-sequence on a clinical 1.5 Tesla MR whole-body unit, and MRS with (1)H-spectroscopic methods (STEAM-sequence) on a 3 Tesla MR whole-body unit. RESULTS: The diffusion of formaldehyde into the tissue was best identified on PD- and T1-weighted images as a band under the liver surface with increasing thickness, penetrating especially fast during the first three days. Spectroscopic measurements revealed the rising formaldehyde concentration in the inner part of the organs. Temperature had no significant influence on the velocity of immersing, but cooling conditions produced less gas-filled caverns due to reduced undesired decomposition processes. CONCLUSION: The spatial and temporal process of ongoing fixation in the liver can be monitored by MRI. MRS confirms a rising concentration of formaldehyde during ongoing fixation.

Fixatives↗

PubMed2004

[Dose dependent effects of the combined beta-gamma-emitter 188Rhenium on the growth of human vessel wall cells].

PURPOSE: To evaluate the dose of (188)Re that completely suppresses growth and clonogenic activity of human aortic smooth muscle cells (haSMC) since these cells are mainly responsible for restenosis occurring after PTA. For comparison, growth and clonogenic activity of endothelial cells (EC) were investigated with corresponding doses. MATERIALS AND METHODS: Two days after plating, haSMC and EC were incubated with (188)Re for five days. The doses applied ranged from 4 to 16 Gy. Cell growth was observed for a period of 20 days (EC) or 30 days (haSMC), respectively. Clonogenic activity was monitored over a period of 20 days for both cell lines. RESULTS: Irradiation caused dose-depend-ent inhibition of cell growth and clonogenic activity both in haSMC and in EC. HaSMC growth was completely blocked with 8 Gy, while EC still showed some proliferation even with 16 Gy. The clonal activity of haSMC was also completely blocked with 8 Gy while EC still showed little clonal activity even with 16 Gy. CONCLUSION: Cell growth of both haSMC and EC can be effectively suppressed in a dose-dependent manner. Only haSMC showed a complete growth arrest with 8 Gy while EC were able to proliferate even with 16 Gy. HaSMC colony formation was completely suppressed after application of 8 Gy, while the EC still showed colony formation activity with 16 Gy. (188)Re has some advantageous properties for intravascular irradiation in comparison to other radionuclides making it an interesting radionuclide for stent coating to prevent restenosis.

Angioplasty, Balloon↗

PubMed2004

[TrueFISP MR imaging to determine the influence of hemodialysis on the myocardial functional parameters in patients with terminal renal insufficiency].

PURPOSE: To assess the characteristic signs of uremic cardiomyopathy in patients with chronic renal failure (CRF) in comparison with healthy volunteers and to determine changes of left ventricular (LV) functional parameters in patients undergoing hemo-dialysis (HD). METHODS AND MATERIALS: Using a 1.5 T Magnetom Sonata system (Siemens, Erlangen), cardiac MR imaging was performed on 26 patients (20 men, 6 women, mean age 54.7 years) and 14 volunteers (8 men, 6 women, mean age 27.7 years). Single-slice true FISP sequences (TR 3.2 ms, TE 1.6 ms, flip angel 58 degrees, matrix 256 x 208, slice thickness 5 mm) were used to obtain contiguous short axis slices covering the whole left ventricle. Patients were examined before and immediately after HD. Cardiodynamic parameters [end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass (MM), cardiac output (CO)] were calculated using the modified Simpson's rule (Argus Software, Siemens). Patient data were compared to reference values taken from healthy volunteers. RESULTS: As a consequence of HD, significant differences (p < 0.01) were observed for EDV (150 + 47 ml/114 + 49 ml), ESV (71 + 46 ml/60 + 56 ml), SV (79 + 25 ml/57 + 27 ml) and CO (3.6 + 1.0 l/min*m (2)/2.6 + 1.1 l/min*m (2)). Although EF (56 + 15 %/53 + 18 %) was decreased after HD, values did not differ significantly (p > 0.05). MM (148 + 47 g/148 + 52 g) and myocardial mass index (80.7 +/- 27.4 g/m (2)/80.1 +/- 9.1 g/m (2)) did not change before and after HD. In all patients, signs of LV-hypertrophy (LVH) and increased CO were diagnosed compared to reference values. In 8 of 26 patients, additional pathology, such as valvular dysfunction or global cardiac insufficiency, was detected. CONCLUSION: Cardiac MRI is an accurate tool to identify uremic cardiomyopathy in patients with chronic renal failure undergoing HD. LV functional parameters could be monitored reliably.

Adult↗

PubMed2004

[Radiologic-histopathologic correlation of microcalcifications from 11g vacuum biopsy: analysis of 3196 core biopsies].

PURPOSE: To perform a statistical evaluation of microcalcifications (MC) from suspicious breast lesions detected by radiography and histopathology. MATERIALS AND METHODS: Histological and radiological detection of calcifications were compared from 116 biopsies in 96 women. Lesions with identical description of calcifications detected in histopathology and radiography were considered concordant, patients with obvious discrepancies discordant. If histological and radiological groups of calcifications were identical in number but differed in location, the case was considered pseudo-concordant. RESULTS: Histopathology classified 24 of 116 lesions as malignant and 92 as benign. A total of 3196 core biopsies were examined, 851 of these contained groups of calcifications or single calcifications. Both modalities detected 579 calcifications, with 169 exclusively detected by radiography and 103 exclusively by histopathology. In 35 cases (30 %) radiologic and pathologic results were concordant, in 6 cases pseudo-concordant (4 %) and in 75 cases (65 %) discordant. The case-based Kappa coefficient was - 0.09 (- 0.24 to 0.07). The 122 calcifications not detected by histopathology were few or single calcifications at the edge of the core that were probably lost during processing, 18 were possible artefacts. Six cores contained calcium oxalate, 3 contained milk of calcium. In 6 cases malignant disease was found after the first examination, hence the cores were not searched thoroughly for the missing calcifications. In the remaining 14 cases, no calcifications were found despite complete processing of the tissue. In 49 of 103 cases of radiologically undetected microcalcifications, the retrospect analysis showed dense tissue areas that probably contained the calcification. The remaining 54 cases contained calcifications, which were too small to be detected radiologically. SUMMARY: Discordant results from pathological and radiological examinations of biopsies can mainly be explained by calcifications at the edge of the specimen lost during processing, which are therefore not detected in histopathology, and calcifications too small to be visualized radiologically.

Adult↗

PubMed2004

3.0 T high-resolution MR imaging of carpal ligaments and TFCC.

PURPOSE: To determine the diagnostic value of 3.0 Tesla MRI for imaging carpal ligaments and triangular fibrocartilage complex (TFCC). Image quality of different optimized MRI sequences is evaluated for high resolution wrist anatomy. MATERIALS AND METHODS: Ten healthy volunteers were examined at 3.0 T and 1.5 T using following sequences: T1 SE, fat-saturated PD-/T2-TSE, TIRM, 3D T1/T2* DESS, 3D-CISS, 2D and 3D T2* MEDIC. Voxel size varied from 0.2 x 0.2 x 1.5 mm (2D sequences) to 0.33 mm (3) and 0.26 mm (3) (3D sequences). Image quality (signal-to-noise-ratio, contrast-to-noise-ratio, artifacts) and carpal ligament/TFCC detection rate were judged by a score. The results obtained from the 3.0 T and 1.5 T devices were compared. RESULTS: With identical voxel size, image matrix and FOV, 3.0 T MRI provided significantly better image quality and ligament detection rates for all sequences in comparison with 1.5 T. The 2D and 3D MEDIC sequences yielded best image quality and detection rates. Excellent image quality and visualization of ligament structures by the fat-suppressed PD-TSE sequence were compromised by a relatively high susceptibility to pulsation and motion artifacts. T1 SE and 3D DESS sequences gave moderate image quality and allowed only partial differentiation between ligament structures. TIRM, T2-TSE and 3D-CISS sequence proved to be unsuitable for examining ligaments at 3.0 T due to their poor image quality and detection rate. CONCLUSION: 3.0 T MRI of the wrist proved to be superior to 1.5 T MRI for high-resolution imaging of carpal ligaments and TFCC using 2D and 3D T2* MEDIC sequences. Clinical studies investigating ligament injuries or carpal instability are recommended for evaluating clinical relevance of high-resolution MRI of the wrist.

Cartilage, Articular↗

PubMed2004

Two-dimensional parallel acquisition technique in 3D MR colonography.

PURPOSE: In-vitro and in-vivo examinations to investigate the influence of one (1D)- and two-dimensional (2D) parallel acquisition techniques (PAT) on contrast-to-noise ratio (CNR) and image quality for bright-lumen 3D MR colonography. MATERIALS AND METHODS: In-vitro measurements were performed on a 1.5 T whole-body MR scanner (MAGNETOM AVANTO(R), Siemens AG, Erlangen) with a standard spoiled 3D gradient-echo (3D GRE) sequence and a volume interpolated 3D GRE (VIBE) sequence using a home-built colon phantom. The relative CNR was determined and image quality evaluated for different acceleration factors (PAT factors). A bright-lumen 3D MR colonography with PAT factors 2, 3, 4 and 6 was performed on a 39-year-old volunteer. The 3D data sets were compared with regard to image quality. RESULTS: The mean relative CNR values for the in-vitro measurements were 1, 0.81, 0.73, 0.52 and 0.4 (3D GRE) and 1, 0.8, 0.65, 0.45 and 0.3 (VIBE) for the PAT factors 1, 2, 3, 4 and 6, respectively. Residual aliasing artifacts not affecting image quality in a distinct manner were visible for 2D PAT, especially for the VIBE sequence. Increasing the PAT factor up to 6 and decreasing the acquisition time down to 10 seconds for the bright-lumen 3D MR colonography could achieve adequate image quality with significantly reduced image artifacts caused by peristalsis and pulsations. DISCUSSION: Even for high PAT factors up to 6, 2D PAT only leads to a moderate CNR loss. For a 3D MR colonography, distinct shorter acquisition times can be achieved with identical resolution.

Colon↗

PubMed2004

[Possibilities of the prophylaxis of arterial restenoses with dexamethasone -- an in-vitro study of human aortic smooth muscle cells].

PURPOSE: To evaluate the effect of dexamethasone on the growth of cultured human aortic smooth muscle cells in an in-vitro model depending on the dose applied. MATERIALS AND METHODS: Commercially available human aortic smooth muscle cells (haSMC) were incubated with different doses of dexamethasone (10(-6), 10(-8), 10(-10) mol/l). For 20 days, the dose-depending effects of dexamethasone on cell growth were studied by analyzing cell proliferation, clonogenic activity as well as cell cycle distribution. In addition, the migratory ability of haSMC was evaluated using a two compartment in-vitro model. RESULTS: Cell growth was reduced in a dose dependent manner. An applied dose of 10(-6) M dexamethasone effectively inhibited cell growth for the follow-up period of 20 days. Cell cycle analysis revealed a G1-phase block which was dose dependent and significant for a dose of 10(-6) M. Also a reduction of haSMC clonogenic activity could be found in the colony formation assays. Finally, dexamethasone reduced the migratory ability of the treated cells significantly for doses of 10(-6) and 10(-8) M. CONCLUSION: Depending on the dose applied, incubation with dexamethasone results in a significant growth reduction of cultured haSMC, which may be due to a drug induced G1-phase block. Dexamethasone also reduces the clonogenic activity as well as the migratory ability of cultured haSMC.

Angioplasty, Balloon↗

PubMed2004

[Evaluation of different 16-row CT colonography protocols using a porcine model].

PURPOSE: To develop and to test an easily produced biological colon model with simulated polypoid lesions. Application of this phantom for the selection of an optimized scan protocol of 16-row CT colonography (CTC) for clinical use. METHODS AND MATERIAL: Six polypoid lesions (1 - 6 mm) were simulated with sutures on the inner face of a porcine colon segment (20 cm). After distending the colon segment with air, the phantom was placed in a water quench and CT scans were performed on a MDCT-scanner (Somatom Sensation 16, Siemens, Forchheim). At constant values for collimation (16x0.75 mm) and voltage (120 kV), 54 different combinations of mAs values (50, 75 and 100 mAs), pitch factors (1, 1.25 and 1.5) and slice thicknesses (0.75, 1.0, 1.5, 2.0, 3.0 and 5.0 mm) were tested systematically. The phantom was scanned in the longitudinal and transverse axis to simulate the different orientation of the colon in the abdomen. Axial slice images and virtual endoscopic views of all data sets were presented separately to 2 radiologists who independently determined number and size of detectable polyps. Dose exposure was measured with an Alderson phantom. RESULTS: The colon model offered a realistic imitation of a polyp-covered, human colon. The experimental set-up allowed a systematic evaluation of polyp detection related to lesion size, orientation of the colon and CTC parameters, with other influencing factors mostly excluded. Polyps were significantly better detected in the longitudinal than in the transverse orientation of the colon. For the detection of lesions of at least 3 mm, a low dose (50 mAs) 16-row CTC should be combined with a pitch of 1.5 and a maximum slice thickness of 3 mm. For the depiction of polyps smaller than 3 mm, slice thickness and pitch should amount to 1 mm and 1.0, respectively. Effective dose of this low dose protocol is 4.08 mSv. CONCLUSION: The porcine colon phantom represents a realistic and easily produced alternative to other colonography models. It allows a preselection of a CTC-protocol for subsequent clinical testings. If the high in vitro performance of the low-dose 16-row CTC-protocol is confirmed on a human collective, the use of 16-row technique would represent a big step for CTC toward a screening method.

Animals↗

PubMed2004

[Clinical value of mammography, ultrasound and MR imaging during the first year after breast conserving therapy of breast cancer].

PURPOSE: To compare the accuracy of lesion detection and characterization and to determine the agreement of observers, methods and timing of mammography (MX), ultrasound (US) and MR imaging (MRI) during the first year after breast conserving therapy. MATERIALS AND METHODS: The study included 20 patients diagnosed with breast cancer of stages equal or inferior to T2 N1bi M0 after breast conserving therapy and subsequent radiotherapy. Patients with any history of breast diseases in the affected or contralateral breast were excluded. Patients were examined before and at 3, 6 and 12 months after adjuvant radiotherapy with MX, US and dynamic MR mammography. Additional US and MRI were performed 3 months after radiotherapy. All 220 examinations were retrospectively read in a randomized order by two independent readers, blinded for the results of the other examinations. The outcome after 2.5 years of follow-up was used as gold standard. Histological examination was available in one case. Lesion detection and specificity were assessed including kappa values for different reliabilities between observers, timing and methods. The kappa values were used to characterize the degree of agreement as follows: > 0.8 very good; 0.6 - 0.8 good; 0.4 - 0.6 fair; 0.2 - 0.4 minimal; and < 0.2 negligible. RESULTS: Based on the interpretation of all available findings (clinical examination, MX, US, MRT and histology in one case), 20 patients observed for a mean period of 2.5 years had no evidence of intramammary recurrence. Therefore the sensitivity of the various methods could not be assessed. The reading of certainly no lesion was given by MRI in 43 %, by MX in 30 % and by US in 5 % of all examinations (p < 0.05). True negative findings were observed by MRI in 94.4 %, by MX in 90.4 % and by US in 82.5 %. Reliability between observers, timing and imaging methods was 0.496, 0.411, and 0.215 for lesion detection and 0.303, 0.282, and 0.030 for lesion characterization. CONCLUSION: Within the first year after breast conserving therapy, MRI was the most confident method for the exclusion of lesions and presented the highest true negative rate. The assessment of dignity of a particular lesion was difficult by all imaging methods, reflected by the weak agreement between observers, methods and timing. The difference between times of readings were marginal in the first year after therapy. Agreement between the different diagnostics methods was minimal to negligible.

Adult↗

PubMed2004

[Clinical implication of parameter-optimized 3D-FISP MR angiography (MRA) in children with aortic coarctation: comparison with catheter angiography].

PURPOSE: To implement parameter-optimized 3D-FISP MR angiography (MRA) with interleaved double-slab excitation and to compare the result with catheter angiography in children with aortic coarctation. MATERIALS AND METHODS: Eighteen children aged 2 - 15 years (mean 9.1 years) underwent MR imaging on a 1.5T body scanner (Magnetom Vision, Siemens, Germany). All patients had undergone correlative catheter angiography. T1-weighted turbo spin echo (TSE) images (TR 600 ms, TE 17 ms, flip 160 degrees, slice thickness 2 - 4 mm) were obtained in axial and parasagittal orientation, followed by an optimized 3D-FISP MR angiography in a sagittal plane (TR 12.5 ms, TE 5.5 ms, flip 22 degrees, matrix 256 x 256, slice thickness 1.25 mm). All children were sedated but on spontaneous breathing. Image quality was graded by two experienced reviewers using a 4-point scoring system. Source images and reformatted maximum intensity projections (MIP) were analyzed for blood-tissue contrast as well as size and focal stenoses of the aortic arch. RESULTS: Aortic coarctation was found in 13 of 18 patients, using the 3D-FISP MRA. A high correlation value (r = 0.96) was found compared to catheter angiography. Image quality was high in 94 % with well defined blood-tissue contrast in all cases. The sensitivity to flow and breathing motion was low. Examination time was about 15 minutes depending on volume of interest and heart rate. Diagnostic accuracy has shown improvement using a combined analysis of source and MIP images. The mentioned technique has provided an excellent display of thoracic vasculature. CONCLUSION: MR imaging represents an excellent tool for non-invasive examination of the cardiovascular system of children. The 3D-MRA allows the recording of a large 3D data set without the use of contrast agent and within an adequate measurement period, particularly in small infants unable to hold their breath. In addition, hemodynamic significance of aortic coarctation, the existence of collateral vessels and other congenital heart diseases can be described reliably by using this technique.

Adolescent↗