Biomedical subjects

M F Reiser

Publications and source records attributed to M F Reiser.

At least 55 records · Page 3Linked to original sources

PubMed2004

[PET-CT interventional tumour therapy].

Multifocal metastatic spread of solid tumours is often a diagnostic and therapeutic challenge. Those patients often cannot undergo curative surgery. Since several years, various types of interventional tumour therapy have been introduced, which may represent a promising option in those cases. In some cases morphological imaging is not able to assess the viability of a previously treated lesion. The combination of computed tomography and positron emission tomography has the potential to ease planning and guiding of interventional procedures and to improve postinterventional control. Due to its higher sensitivity and specificity, PET/CT enables for a more precise selection of patients for interventional tumor therapy. The success of a particular therapy could be assessed with greater accuracy using PET/CT as compared with the separate modalities. PET/CT was also able to improve planning and guiding interventional therapy. As of yet, no data are available concerning the success rate and long-term survival of PET/CT associated interventional procedures.

Adult↗

PubMed2004

[Modern visualization of the liver with MRT. Current trends and future perspectives].

This contribution provides an overview and imparts basic knowledge on pertinent technical developments in magnetic resonance imaging (MRI) of the liver: 3D sequences, respiratory triggering, parallel imaging, and 3 Tesla (3T). 3D sequences can be used as T1-weighted (T1w) sequences for analyzing dynamics of contrast enhancement or as T2w sequences for MR cholangiography. Consistent improvements in respiratory triggering make it possible to obtain good image quality on T2w scans even in patients unable to hold their breath. Parallel imaging as a universal technique to accelerate image acquisition is particularly appropriate for MRI of the liver, and it has been shown that the reduced acquisition time is not achieved at the expense of image quality. Further progress in MRI of the liver can be expected with use of the 3T systems, but hitherto irrelevant problems must still be solved. Overall the innovations presented here, applied alone or in combination, facilitate rapid, robust, and high-quality MRI diagnostic assessment of the liver.

Algorithms↗

PubMed2004

[Value of electron beam tomography (EBT)].

Electron beam tomography (EBT) has been scientifically evaluated to a much lesser degree for non-cardiac indications than for cardiac purposes. Therefore, four groups of investigators in Berlin (2), Mannheim and Munchen, which were supported by the Deutsche Forschungsgemeinschaft (DFG), included applications outside the heart in their evaluation of EBT technology. EBT has proven useful to look for pulmonary embolism and to assess other vessels (aorta, aortic branches, and intracranial arteries). Imaging of the lung parenchyma benefits from its intrinsic high contrast and from the fast data acquisition of EBT. Limited photon efficiency, higher radiation exposure, increased noise levels and other artifacts, however, markedly reduce the value of EBT for imaging of low contrast objects compared to conventional spiral CT and multislice CT (MSCT), compromising, in particular, the morphologic depiction of parenchymal abdominal organs and the brain. Consequently, scientific studies to further evaluate EBT for scanning of the brain and parenchymal abdominal organs were not pursued. Radiation exposure for non-cardiac EBT studies is up to three times higher than that for respective spiral CT studies, and in children EBT can only be advocated in select cases. Radiation exposure for the various prospectively triggered cardiac examination protocols of EBT is lower than that for conventional coronary angiography. Radiation exposure in cardiac multislice CT exceeds severalfold that of EBT, but the dose efficiency of EBT and MSCT are similar due to higher spatial resolution and less image noise of MSCT. In addition, modifications of MSCT (ECG pulsing) can further reduce radiation exposure to the level of EBT. Technical improvements of the EBT successor scanner "e-Speed" enable faster data acquisition at higher spatial resolution. Within comparative studies, the "e-Speed" will have to prove its value and competitiveness, particularly in comparison with multislice CT. After profound scientific assessment in a multicenter evaluation supported by the Deutsche Forschungsgemeinschaft (DFG) and regardless of the specific suitability of electron beam tomography for various cardiac and some non-cardiac indications, the investigators unanimously find the electron beam tomograph Evolution C150 XP not suitable as a whole body CT scanner.

Age Factors↗

PubMed2004

[Diagnostic value of electron-beam computed tomography (EBT). I. Cardiac applications].

Electron beam tomography (EBT) directly competes with other non-invasive imaging modalities, such as multislice computed tomography, magnetic resonance imaging, and echocardiography, in the diagnostic assessment of cardiac diseases. EBT is the gold standard for the detection and quantification of coronary calcium as a preclinical sign of coronary artery disease (CAD). Its standardized examination protocols and the broad experience with this method favor EBT. First results with multislice CT indicate that this new technology may be equivalent to EBT for coronary calcium studies. The principal value of CT-based coronary calcium measurements continues to be an issue of controversy amongst radiologists and cardiologists due to lack of prospective randomized trials. Coronary angiography with EBT is characterized by a high negative predictive value and, in addition, may be indicated in some patients with manifest CAD. It remains to be shown whether coronary angiography with multislice CT is reliable and accurate enough to be introduced into the routine work-up, to replace some of the many strictly diagnostic coronary catheterizations in Germany and elsewhere. Assessment of coronary stent patency with EBT is associated with several problems and in our opinion cannot be advocated as a routine procedure. EBT may be recommended for the evaluation of coronary bypasses to look for bypass occlusions and significant stenoses, which, however, can be equally well achieved with multislice CT. Quantification of myocardial perfusion with EBT could not replace MRI or other modalities in this field. EBT has proven to be accurate, reliable and in some instances equivalent to MRI, which is the gold standard for the quantitative and qualitative evaluation of cardiac function. Some disadvantages, not the least of which is the limited distribution of electron beam scanners, favor MRI for functional assessment of the heart.

Adult↗

PubMed2004

Crohn disease of the small bowel proximal to the terminal ileum: detection by MR-enteroclysis.

BACKGROUND: Although Crohn disease (CD) can affect the entire alimentary tract, the proportion of patients with small-bowel inflammation proximal to the terminal ileum is still unclear. Magnetic resonance imaging (MRI) combined with small-bowel enteroclysis can detect inflammatory lesions of the small bowel. Hence, we applied MR-enteroclysis to assess the percentage of patients with small-bowel inflammation proximal to the terminal ileum among patients with CD and abdominal pain. METHODS: Twenty-five consecutive patients with low, active CD of the colon and/or terminal ileum and episodes of abdominal pain were examined by both MR-enteroclysis and conventional enteroclysis. The findings of MR-enteroclysis were compared with endoscopic and histological results in the terminal ileum and conventional enteroclysis in the small bowel proximal to the terminal ileum. RESULTS: In 13 of the 25 patients, inflammation of the small bowel proximal to the terminal ileum was shown by MR-enteroclysis, whereas in only 4 of the 25 patients, signs of inflammation of the small bowel proximal to the terminal ileum were shown by conventional enteroclysis, all of which were demonstrated by MR-enteroclysis. MR-enteroclysis confirmed the findings in 22 of 25 patients in whom endoscopy and histology had shown inflammation (16 of 18) or no inflammation (6 of 7) of the terminal ileum. CONCLUSION: In symptomatic patients with CD even of low activity, inflammation of the small bowel proximal to the terminal ileum is frequent.

Adult↗

PubMed2003

[Value of various imaging modalities for diagnostic work-up of tumors of the adrenal gland].

OBJECTIVE: This paper describes the value of various imaging modalities for diagnostic work-up of tumors of the adrenal gland. METHODS: Results of the literature are reviewed. An optimized examination protocol for computed tomography (CT) and magnetic resonance imaging (MRI) is shown for assessment and differentiation of unclear lesions of the adrenal gland. RESULTS: Measurements of attenuation in the native examination as well as delayed enhancement are the cornerstones in the CT diagnostics of tumors of the adrenal gland. In MRI, chemical-shift imaging and evaluation of signal characteristics in T1- and T2-weighted images are most important for characterization even in unclear cases. CONCLUSION: CT and MRI play the major role in imaging of adrenal gland tumors. Whereas CT is less expensive and widely available,MRI provides advantages in unclear cases because of the excellent tissue contrast and the superior characterization.

Adrenal Cortex Neoplasms↗

PubMed2003

[Assessment of axonal degeneration on Alzheimer's disease with diffusion tensor MRI].

PURPOSE: Alzheimer disease (AD) causes cortical degeneration with subsequent degenerative changes of the white matter. The aim of this study was to investigate the extent of white matter tissue damage of patients with Alzheimer's disease in comparison with healthy subjects using diffusion tensor MRI (DTI). The value of integrated parallel imaging techniques (iPAT) for reduction of image distortion was assessed. MATERIAL AND METHODS: We studied 9 patients with mild AD and 10 age and gender matched healthy controls. DTI brain scans were obtained on a 1.5 tesla system (Siemens Magnetom Sonata) using parallel imaging (iPAT) and an EPI diffusion sequence with TE/TR 71 ms/6000 ms. We used an 8-element head coil and a GRAPPA reconstruction algorithm with an acceleration factor of 2. From the tensor, the mean diffusivity (D), the fractional anisotropy (FA), and the relative anisotropy (RA) of several white matter regions were determined. RESULTS: FA was significantly lower (p <0,05) in the white matter of the genu of corpus callosum from patients with AD than in the corresponding regions from healthy controls. There was a trend observed for slightly higher ADC values in the AD group (p=0,06). No significant changes were observed in the regions of the splenium, internal capsule, pericallosal areas, frontal, temporal, parietal, and occipital lobe. The images obtained with iPAT contained substantially less susceptibility artefacts and were less distorted than images acquired with non-parallel imaging technique. CONCLUSIONS: DTI is a method with potential to assess early stages of white matter damage in vivo. The altered FA and ADC values in the genu of corpus callosum of patients with AD presumably reflect the microscopic white matter degeneration. Acquisition time can be reduced by iPAT methods with less image distortion from susceptibility artefacts resulting in a more accurate calculation of the diffusion tensor.

Adult↗

PubMed2003

[Technique and methods in uterine leiomyoma embolization].

OBJECTIVE: Uterine leiomyomas are the most common benign tumors of the female urogenital tract. Beside the classic surgical treatment options the minimal-invasive embolization therapy of the leiomyomas increasingly gains importance world-wide. Technique, complications, and results of uterine leiomyoma embolization will be presented. METHODS: After careful evaluation of indications for embolization the procedure is mostly performed under conscious sedation. A single-sided femoral access route together with cross-over technique generally allows for a flow-directed embolization via both uterine arteries. After embolizing the vessels supplying the tumor, the uterine arteries should be still patent. RESULTS: The success rate of embolization of uterine leiomyomas ranges between 85 and 100%, whereas a reduction in size of the tumors in 42 to 83% and a relief of symptoms in up to 96% can be achieved. The total complication rate is about 10% with mainly "minor complications". Worldwide only three deaths following embolization of uterine leiomyomas were reported. CONCLUSION: The high technical and clinical success rate together with a low complication rate make the embolization of uterine leiomyomas a minimally-invasive alternative to the classic treatment. As long term results are not available indication to embolization of uterine leiomyomas must be carefully established in consensus with gynecologists.

Adult↗

PubMed2003

[State and development of uterine myoma embolization in Germany].

BACKGROUND: To evaluate the current situation and implementation of embolization of uterine leiomyomas into the treatment concept in women with symptomatic uterine leiomyomas in Germany. MATERIAL AND METHODS: A questionnaire addressing the clinical background of uterine myomas, recommended treatment concepts, preclinical evaluation, technical approach and complications was sent to 164 departments of gynecology and radiology in Germany. RESULTS: 33 radiological departments and 19 gynecological departments submitted a completed questionnaire. Only 7 departments of radiology reported to have own experience with embolization of uterine leiomyomas, while only 2 departments of gynecology considered embolization as an alternative treatment option in patients with symptomatic leiomyomas. 18/33 radiological departments offer this treatment option but get no patient referrals. Agreement was found concerning the indications for treatment, preclinical evaluation by ultrasound and MRI, preferable location of treatable fibroids, technical approach and pain management. CONCLUSION: The embolization of uterine leiomyomas in patients with symptomatic myomas is regardless of the well documented high efficacy and low complication rate not yet an established treatment option in Germany. Interventional radiologists and gynecologists have to evaluate the indications for the embolization of uterine leiomyomas together before the procedure is advised to the patient, because it seems mandatory to add this procedure to the standard armamentarium of treatment options in uterine myomas.

Adult↗

PubMed2003

[Percutaneous vertebroplasty (pv): indications, contraindications, and technique].

PURPOSE: Percutaneous vertebroplasty (pv) is a worldwide increasingly performed interventional therapeutic procedure. This article addresses indications, patient preparation, technical requirements and approach as well as possible complications of percutaneous vertebroplasty. TECHNIQUE: Percutaneous vertebroplasty is a technique consisting in an injection of bone cement into a vertebral body under imaging guidance. This procedure is performed to relief pain and support the mechanical stability in partially collapsed vertebral bodies. RESULTS: In the management of spinal compression fractures secondary to osteoporosis, myeloma, osteolytic metastases and aggressive hemangiomas, percutaneous vertebroplasty yields analgesic effect, and provides additional fortification in weakened segments of the vertebral column. Contraindications include major bleeding disorders, radicular pain and pain caused by compression of the myelon. DISCUSSION: Percutaneous vertebroplasty results in prompt pain relief and rapid rehabilitation. In experienced hands, using correct technique, pv is a safe and effective procedure for treating pain, caused either by osteoporotic or malignant vertebral compression fractures.

Aged↗

PubMed2003

[Vertebroplasty in osteoporotic vertebral compression].

BACKGROUND AND PURPOSE: Osteoporotic vertebral compression fractures are a frequently encountered clinical problem. We aimed to perform a critical, structured review of the current literature and to compare the results with our own experiences. MATERIAL AND METHODS: A structured review of 7 studies about vertebroplasty in osteoporotic compression fractures was performed; each study assessed at least 16 patients and was published in English since 1997. The results were compared to our own experience in 22 patients treated in 2002. RESULTS: Over the past decade, vertebroplasty has increasingly been performed for the treatment of painful osteoporotic vertebral body compression fractures. In good correlation with our own results, all authors reported a significant improvement of pain immediately after treatment and a reduction of pain of up to 90% within 24 h after vertebroplasty. Furthermore, a significant reduction in the use of analgetics and a substantial improvement of functional status has been described in recent studies. In our own evaluation, we were also able to demonstrate a significant improvement of pain after vertebroplasty in 17 of 22 (77%) of our patients. 18 of 22 (82%) patients were able to diminish or even discontinue their analgesic medication. DISCUSSION: Reported results for vertebroplasty have demonstrated a rapid improvement in pain and physical functioning in patients with osteoporotic vertebral compression fractures. Percutaneous vertebroplasty has proven to provide a valuable treatment option for osteoporotic vertebral compression fractures.

Bone Cements↗

PubMed2003

[Congenital malformations of the cerebral brain. 1: Malformations of the cerebral cortex].

Disorders of supratentorial cortical development are usually divided into disorders of neuronal proliferation, neuronal migration and cortical organization. Based upon molecular biologic discoveries, a modified classification has recently been proposed. The category of malformations of abnormal neuronal and glial proliferation and apoptosis now includes microlissencephalies, megalencephalies, hemimegalencephalies and cortical dysplasias with balloon cells. Malformations due to abnormal neuronal migration now subsume the lissencephaly spectrum including the subcortical band heterotopias, the cobblestone complex and the group of heterotopias. Malformations due to abnormal cortical organization include the spectrum of polymicrogyria and schizencephaly as well as cortical dysplasias without balloon cells. High-resolution magnetic resonance imaging (MRI) has led to an increasing awareness of these malformations. This article aims to illustrate the classification, MRI presentation and relevant clinical features of the most commonly encountered disorders of cortical development.

Brain↗

PubMed2003

[Congenital malformations of the brain. 2: Malformations of the corpus callosum and holoprocencephalies].

The corpus callosum is formed between the 7th and the 20th gestational week. If this process is disrupted, partial or complete callosal agenesis may ensue. As large parts of the supra- and infratentorial brain are created during this critical period, associated anomalies need always to be searched for when callosal agenesis is present. Associations with neuro-genetic syndromes also exist. The corpus callosum is generally formed from front to back ("front-to-back rule"). Therefore, a partial callosal agenesis usually involves the posterior portion of the corpus callosum, while a secondary lesion of the corpus callosum does not follow this rule. Holoprosencephalies are a notable exception to this rule, as the frontal part of the corpus callosum is absent in spite of their classification as congenital malformations. They represent a disturbance of the differentiation and cleavage of the prosencephalon with a disruption of the separation of the cerebral hemispheres. Holoprosencephalies can be due to genetic causes, but also to intrauterine infections or other teratogenic causes. The holoprosencephalies are subdivided into alobar, semilobar and lobar holoprosencephalies. This article aims to describe the most important features of callosal agenesis and holoprosencephalies highlighting the respective imaging characteristics.

Abnormalities, Multiple↗

PubMed2002

Reproducibility of coronary calcium quantification in repeat examinations with retrospectively ECG-gated multisection spiral CT.

High reproducibility is a key requirement for coronary calcium scoring in follow-up examinations. We investigated the inter-examination reproducibility of calcium scoring with retrospectively ECG-gated multisection spiral CT (MSCT). Fifty patients were examined twice with MSCT. Slices were reconstructed with retrospective ECG gating in the diastolic phase with 3-mm slice width and up to 125-ms temporal resolution. We calculated the Agatston score, calcium volume with and without isotropic interpolation, and calcium mass, and derived the mean and median variability. We investigated the change of variability with use of 3-mm non-overlapping and overlapping increments (2, 1.5, 1 mm). Use of overlapping increment results in considerably reduced interscan variability. We observed a minimum mean variability of 12% and a minimum median variability of 9% for the Agatston score. For volume and mass quantification we obtained a minimum mean variability of 7.5% and a minimum median variability of 5%. Multisection spiral CT enables coronary calcium quantification with high reproducibility in follow-up examinations mainly founded on image data with reduced partial-volume errors due to overlapping increment.

Adult↗

PubMed2002

[Diagnostic evaluation of the craniocervical vascular system with a 16-slice multi-detector row spiral CT. Protocols and first experiences].

PURPOSE: The newly developed 16-slice multi detector row computed tomography (MDCT) allows for isotropic imaging at rotation times under 500 ms. We aim to describe our first experiences with this novel technology in the diagnostic imaging of the craniocervical vascular system. METHODS: The craniocervical vascular system of 8 consecutive patients was examined with a standardized protocol with the new 16-slice MDCT. The volume covered included the carotid arteries from their origin at the aortic arch and the intracranial arterial and venous vessels in their entirety. Homogeneity of contrast, contrast-to-parenchyma ratios, image quality and radiation doses were assessed. RESULTS: A homogeneous vessel-to-parenchyma ratio was reached in the carotids as well as in the intracranial arterial and venous vessels. Image quality was rated as excellent in all patients. The estimated mean effective radiation dose amounted to 2.31 mSv +/-0.57, the mean dose length product to 608 mGy*cm +/-151. CONCLUSION: The newly developed 16-slice MDCT technology appears to be a promising tool in the diagnostic assessment of the cervicocranial vessels.

Aged↗

PubMed2002

[CT angiography of the coronary arteries with a 16-row spiral tomograph. Effect of spatial resolution on image quality].

PURPOSE: To evaluate image quality of coronary CT angiography with retrospectively ECG-gated 16 multi-slice spiral CT (MSCT), reconstructed with 0.75 mm slice thickness for optimal spatial resolution and with 1.3 mm slice thickness, to produce spatial resolution comparable to a 4-MSCT. MATERIALS AND METHODS: Ten patients underwent coronary CT angiography with a 16-MSCT (Siemens Sensation 16, Forchheim, Germany) with 0.75 mm detector collimation. Raw helical CT data were retrospectively reconstructed using two different settings. Setting A: B20f smooth kernel, axial MPR with 1.3 mm slice thickness and 0.7 mm increment. Setting B: B35f "HeartView" medium-smooth kernel, 0.75 mm slice thickness, 0.5 mm increment. In the axial slices two regions of interest (ROIs) were placed in the area of the aortic root (AR) and more caudal in the area of the left ventricle (LV). Image noise was determined by the standard deviation of the CT numbers.Two readers determined visibility of coronary arteries by standardized maximum intensity projections (MIP) post-processing in left, right anterior and left anterior oblique projection plane from setting A and B. Each projection was rated on a five point rating scale concerning plaque delineation. Points determined for each data set were summed up and used for comparison. RESULTS: No significant difference between the CT-numbers was found for setting A and B (A: 283.0 in AR/295.9 in LV and B: 282,9 in AR/297.2 in LV; p >0.2). However, the image noise was significantly different for setting A and B (A: 4.46 in AR/1.67 in LV and B: 8.16 in AR/7.38 in LV; p <0.01). Better delineation of the coronary arteries and atherosclerotic lesions could be achieved from MIP projections in setting B compared to setting A. CONCLUSION: Higher image noise is present in coronary 16-MSCT with thin-slice reconstruction compared to simulated 4-MSCT. However the MIP-reconstructions benefit most from the higher spatial resolution.

Coronary Angiography↗

PubMed2002

[Radiation dose and dose reduction in multidetector row CT (MDCT)].

Since its introduction a few years ago, multidetector row CT (MDCT) has become a widely used diagnostic procedure and has been proven to be a valuable tool for various indications. A major issue using this new modality is the inherent risk of applying increased radiation exposure, when compared to single-slice CT or other imaging modalities.However, MDCT offers some valuable options to save radiation exposure, such as choosing optimized exposure parameters or its superior dose efficiency in comparison to single-slice CT. Multi-phasic examinations should be restricted to indications where definitely necessary. Modern scanners offer intelligent tools for further reduction of radiation dose, such as ECG- or bodyshape-based realtime dose modulation. A new field of applications is the low-dose CT for early detection of diseases. While acquiring thin slices with high spatial resolution, the dose can be reduced to similar values as in conventional radiography, especially when examining under high-contrast conditions. Using all these various options available, radiation exposure can sometimes even be lower than using a conventional single-slice helical CT.

Artificial Intelligence↗

PubMed2002

[New abdominal CT angiography protocol on a 16 detector-row CT scanner - first results].

PURPOSE: Purpose of this study was the implementation of a new abdominal CT angiography protocol on a 16 detector-row CT scanner and the comparison to selective catheter angiography. METHODS: 76 patients with various vascular disorders underwent abdominal CT angiography on a recently developed 16 detector-row CT scanner using submillimeter slice collimation (16 x 0.75 mm). Results were compared with mesenteric and/or hepatic angiography in 17 patients performed during tumor embolization. Opacification was provided using individually tailored contrast application with a test bolus setting. To evaluate the contrast injection protocol density measurements within the vessel lumen were performed. RESULTS: Diagnostic image quality was achieved in all patients with angiographic comparison (n = 17). Within the hepatic and mesenteric vasculature up to 4th generation vessels could be identified. Compared to selective angiography CT angiography provided equivalent morphologic information up to the detectable vessel generation. With the applied contrast application regimen there were no significant differences in vessel enhancement along the abdominal aorta and iliac arteries. CONCLUSION: 16 detector-row CT enables whole abdominal angiographic studies with submillimeter resolution in a single breath-hold. The improved spatial resolution enables for high quality 3D visualization. Compared to invasive angiography, 16 detector-row CT reveals equivalent morphologic information.

Abdomen↗