153 research outputs found
Chemotherapy-induced suppression to adenoma or complete suppression of the primary in patients with stage IV colorectal cancer: report of four cases
No full textBackground Although modern chemotherapy of stage IV advanced colorectal cancer (CRC) has impressively improved overall survival, the response of the primary tumor has not been studied because surgical resection of the primary continues to be the standard procedure in stage IV CRC. Aim Long-term follow-up of the primary in patients with stage IV CRC under chemotherapy. Methods and results Here we report on the histological changes in the primary tumor in four patients suffering from stage IV CRC. Systemic chemotherapy was started immediately after endoscopic tumor debulking in three cases. In one case no endoscopic intervention was performed before chemotherapy. Neither macroscopic nor histological evidence for malignant tumor growth was found at the former site of the primary after 6, 23, 26 or 48 months, respectively. Two patients had a complete suppression of the primary, two patients had an adenoma at the former site of the primary. To date, three patients have died because of progression of liver metastases and one patient is still alive with no signs of tumor growth. Conclusion The four cases illustrate that today's chemotherapy may effectively induces suppression of the primary in CRC. The development of CRC may follow different pathways
3D MR angiography of the entire aorta: modified application of the body-phased array coil for a single-shot technique
No full textObjective: Evaluation of different contrast-enhanced MR angiography imaging protocols for visualization of the entire aorta in breath-hold technique. Methods ann patients: Three different CE (0.15 mmol/kg) MRA protocols were evaluated by phantom and patient studies: (1) two separate MRA with conventional application of the body-phased array coil; (2) a single-shot MRA with modified application of the body-phased array coil; (3) a single-shot MRA with the body coil. Duplex sonography, CTA and DSA were used as standard of reference. Results: In all examinations the entire aorta could be visualized. The best SNR was acquired with protocol (1). The SNR of protocol (2) was reduced if the sagittal body diameter of the patient was greater than 20 cm and decreased significantly with diameters over 30 cm. By the use of protocol (3) the SNR was notably poor. The quality scored for the visualization of the entire aorta was 97.5% (protocol 1), 92.5% (protocol 2); and 80.0% (protocol 3). Conclusion: In most cases the modified application of the body-phased array coil allows the imaging of the entire aorta as a single-shot 3D CE MRA in diagnostic quality. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved
Implant detectibility of intervertebral disc spacers in post fusion MRI: evaluation of the MRI scan quality by using a scoring system - an in vitro study
No full textIntroduction Intervertebral spacers for anterior spine fusion are made of different materials, such as titanium and cobalt chromium alloys and carbon fiber-reinforced polymers. Implant-related susceptibility artifacts can decrease the quality of MRI scans. The aim of this cadaveric study was to demonstrate the extent that implant-related MRI artifacting affects the postfusion differentiation of determined regions of interest (ROIs). Methods In six cadaveric porcine spines, we evaluated the postimplantation MRI scans of a titanium, cobalt-chromium and carbon spacer that differed in shape and surface qualities. A spacer made of human cortical bone was used as a control. A defined evaluation unit was divided into ROIs to characterize the spinal canal as well as the intervertebral disc space. Considering 15 different MRI sequences read independently by an interobserver-validated team of specialists the artifact-affected image quality of the median MRI slice was rated on a score of 0-3. A maximum score of 18 points (100%) for the determined ROIs was possible. Results Turbo spin echo sequences produced the best scores for all spacers and the control. Only the control achieved a score of 100%. For the determined ROI maximum scores for the cobalt-chromium, titanium and carbon spacers were 24%, 32% and 84%, respectively. Conclusion By using favored T1 TSE sequences the carbon spacer showed a clear advantage in postfusion spinal imaging. Independent of artifact dimensions, the scoring system used allowed us to create an implant-related ranking of MRI scan quality in reference to the bone control
Impact of breast density on computer-aided detection in full-field digital mammography
No full textThe goal of this study was to evaluate the performance of a computer-aided detection (CAD) system in full-field digital mammography (Senographe 2000D, General Electric, Buc, France) in finding out carcinomas depending on the parenchymal density. A total of 226 mediolateral oblique (MLO) and 186 craniocaudal (CC) mammographic views of histologically proven cancers were retrospectively evaluated with a digital CAD system (ImageChecker V2.3 R2 Technology, Los Altos, CA, USA). Malignant tumors were detected correctly by CAD in MLO view in 84.85% in breasts with parenchymal tissue density of the American College of Radiology (ACR) type 1, in 70.33% of the ACR type 2, in 68.12% of the ACR type 3, and in 69.70% of the ACR type 4. For the CC view, similar results were found according to the ACR types. Using the chi-square and McNemar tests, there was no statistical significance. However, a trend of better detection could be seen with decreasing ACR type. In conclusion, there seems to be a tendency for breast tissue density to affect the detection rate of breast cancer when using the CAD system
Preclinical evaluation by flat-panel detector-based volumetric CT versus MRI of intervertebral spacers implanted in a porcine model
No full textBACKGROUND CONTEXT: Image quality and implant detectability by conventional imaging methods are suboptimal for perioperative spinal diagnostics, primarily limited by implant-related artifacts. PURPOSE: To evaluate the imaging quality of various intervertebral spacers examined by flat-panel detector-based volumetric computed tomography (FD-VCT) versus magnetic resonance imaging (MRI). STUDY DESIGN/SETTING: A preclinical comparative study on an experimental porcine model. The study was performed at a university research facility. METHODS: Three different intervertebral spacer types (titanium, carbon fiber-reinforced polymer, cobalt-chrome-molybdenum) were implanted in a cadaveric porcine spine and then examined by MRI using T1-weighted spin echo (T1w-SE) and turbo spin echo (T1w-TSE) sequences. Comparative imaging was performed with an experimentally approved FD-VCT prototype featuring two-dimensional and three-dimensional imaging and high isotropic spatial resolution. Data analysis focused on spacer shape, implant positioning, and implant-bone interface. RESULTS: Compared with MRI, and despite the use of T1w-SE and T1w-TSE sequences, the image quality and delectability of all target characteristics were better with FD-VCT absent the usual artifacts. Using its option for implant-specific imaging, the experimental FD-VCT imager allowed reliable determination of additional variables such as dimension and volume. CONCLUSIONS: This experimental study provides initial evidence that FD-VCT produces excellently sharp, high-accuracy, artifact-free imaging quality that is superior to MRI in distinguishing key characteristics of intervertebral implants in a preclinical setting. (c) 2007 Elsevier Inc. All rights reserved
Chemotherapy-induced suppression to adenoma or complete suppression of the primary in patients with stage IV colorectal cancer: report of four cases
No full textBackground Although modern chemotherapy of stage IV advanced colorectal cancer (CRC) has impressively improved overall survival, the response of the primary tumor has not been studied because surgical resection of the primary continues to be the standard procedure in stage IV CRC. Aim Long-term follow-up of the primary in patients with stage IV CRC under chemotherapy. Methods and results Here we report on the histological changes in the primary tumor in four patients suffering from stage IV CRC. Systemic chemotherapy was started immediately after endoscopic tumor debulking in three cases. In one case no endoscopic intervention was performed before chemotherapy. Neither macroscopic nor histological evidence for malignant tumor growth was found at the former site of the primary after 6, 23, 26 or 48 months, respectively. Two patients had a complete suppression of the primary, two patients had an adenoma at the former site of the primary. To date, three patients have died because of progression of liver metastases and one patient is still alive with no signs of tumor growth. Conclusion The four cases illustrate that today's chemotherapy may effectively induces suppression of the primary in CRC. The development of CRC may follow different pathways
Semi-automatic classification of skeletal morphology in genetically altered mice using flat-panel volume computed tomography.
No full textRapid progress in exploring the human and mouse genome has resulted in the generation of a multitude of mouse models to study gene functions in their biological context. However, effective screening methods that allow rapid noninvasive phenotyping of transgenic and knockout mice are still lacking. To identify murine models with bone alterations in vivo, we used flat-panel volume computed tomography (fpVCT) for high-resolution 3-D imaging and developed an algorithm with a computational intelligence system. First, we tested the accuracy and reliability of this approach by imaging discoidin domain receptor 2- (DDR2-) deficient mice, which display distinct skull abnormalities as shown by comparative landmark-based analysis. High-contrast fpVCT data of the skull with 200 microm isotropic resolution and 8-s scan time allowed segmentation and computation of significant shape features as well as visualization of morphological differences. The application of a trained artificial neuronal network to these datasets permitted a semi-automatic and highly accurate phenotype classification of DDR2-deficient compared to C57BL/6 wild-type mice. Even heterozygous DDR2 mice with only subtle phenotypic alterations were correctly determined by fpVCT imaging and identified as a new class. In addition, we successfully applied the algorithm to classify knockout mice lacking the DDR1 gene with no apparent skull deformities. Thus, this new method seems to be a potential tool to identify novel mouse phenotypes with skull changes from transgenic and knockout mice on the basis of random mutagenesis as well as from genetic models. However for this purpose, new neuronal networks have to be created and trained. In summary, the combination of fpVCT images with artificial neuronal networks provides a reliable, novel method for rapid, cost-effective, and noninvasive primary screening tool to detect skeletal phenotypes in mice
Flat-panel-detector-based volumetric CT: performance evaluation of imaging for skeletal structures of small animals in comparison to multislice CT
No full textObjectives: The aim of this study was to compare the image performance of silicon-based flat-panel-detector-based volumetric computed tomography (fpVCT) to multislice spiral computed tomography (MSCT) for the visualization and detail delectability of skeletal structures in rodents of different development stages. Materials and Methods: Rodents of different development stages were imaged with fpVCT (GE prototype with circular gantry with two 1024 x 1024, 200-mu m pixel size, amorphous silicon/Cesium lodid (Csl) flat-panel detector) and eightslice MSCT (LightSpeed Ultra). Imaging parameters (80 kVp, 100 mA) and the position of the rodents were identical in both techniques. Image quality, detail delectability, and contour of skeletal structures were judged by two observers in consensus using a 4-point scale (1=unsatisfactory... 4=good). Findings were displayed and evaluated in axial slices, multiplanar reconstructions (MPR), maximum intensity projections (MIP) and volume rendering technique (VRT) in both modalities. Mean and standard of error of mean were calculated. Results: In axial slices, visualization and detail delectability of very subtle skeletal structures, e.g., the basis of the skull was better in fpVCT than in MSCT (4 vs. 2 points). The MPRs of fpVCT showed less artifacts and more details than those of the MSCT. The MIPs and VRTs of the fpVCT demonstrated best image quality in all rodents of different development stages, whereas MSCT showed significant artifacts. Conclusion: fpVCT outperformed MSCT in imaging of small rodents. Due to the truly isotropic volume data set with high spatial resolution, fpVCT is a powerful tool in evaluating detailed skeletal structures. (c) 2007 Elsevier Inc. All rights reserved
The approximate planimetric method: a simple, rapid and reliable method for estimation of lesion size in acute ischemic stroke
No full textMagnetic resonance imaging is increasingly used in stroke trials for early diagnosis and follow-up of lesion size. Since volumetric measurement remains a laborious and time-consuming task, a rapid and reliable method for the assessment of lesion size has been developed and validated in diffusion weighted imaging (DWI) and fluid attenuated inversion recovery (FLAIR) sequences. These were serially obtained in 40 patients less than 8 h after the onset of symptoms of a middle cerebral artery territory stroke (day 1), as well as on days 3 and 18. For each of 16 (DWI) or 20 (FLAIR) transverse sections obtained on each occasion, lesion size was estimated as a percentage of the total hemisphere. Percentage values from all sections were summed up and expressed as arbitrary units. Results obtained using this approximate planimetric method (APM) were compared with those from a standard volumetric approach. Lesion volumes as determined by both methods were highly correlated (DWI: r=0.966, FLAIR: r=0.979, p<0.001). To conclude, the APM is simple, rapid and reliable for the estimation of lesion size in acute ischemic stroke. It can be recommended for broader application in clinical trials
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