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E Grabbe

Publications and source records attributed to E Grabbe.

At least 91 records · Page 5Linked to original sources
PubMed1998

[Contrast media-enhanced 3D MR angiography of the peripheral vessels using a "tracking technique": preliminary results].

PURPOSE: A single bolus contrast-enhanced (CE) 3D MR angiography (MRA) of the peripheral vessels was evaluated using a combination of two surface coils with manual incrementation of the patient table. METHODS: Fifteen patients with peripheral arterial occlusive disease were examined using an ultrafast CE 3D MRA (TR/ TE/FA 5 ms/2 ms/30 degrees). For imaging of the vessels from the distal aorta to the arteries of the lower limbs a combination of a body-array coil and a flexible extremity coil was applied. A coil-interface was designed for a connection of the two coils. The examinations were performed after a single bolus of 0.15 mmol Gd-DTPA/kg. The tracking technique included a manual incrementation of the patient table and the coil-interface had to be switched from the body-array coil to the flexible extremity coil. For acquisition delay measurement of the MR sequence the individual transit times of the contrast material were detected by using a test bolus. RESULTS: CE 3D MRA was technically successful in 14/15 cases. In one case two vascular segments were not imaged. The qualitative evaluation of all vascular segments documented a high quality without any significant differences between the proximal and the distal arteries (p < 0.05). All hemodynamically significant stenoses (n = 15) and all vessel occlusions (n = 36) were detected. CONCLUSION: The single bolus CE 3D MRA using a tracking technique is a favourable method in the evaluation of patients with peripheral arterial occlusive disease.

Arterial Occlusive Diseases↗
PubMed1998

[A new specimen radiography device with a maximum 20-fold magnification for breast diagnosis].

PURPOSE: A radiography system specially developed for specimen radiography and allowing maximal 20-fold magnification is presented. The efficiency of the system was tested and compared with that of conventional magnification mammography systems. METHODS: 23 surgical and 90 core biopsies of the breast were examined for detection of microcalcifications. As criteria the number of identifiable calcifications, their shape and configuration as well as tissue contrast were chosen. RESULTS: The new technique detected about 400% more microcalcifications, 200% more core and 50% more surgical biopsies containing calcifications. Thus, in a few cases, additional core biopsies were unnecessary. Moreover, this new system yielded additional information for the pathologist and surgeon concerning the exact localisation of suspicious lesions that facilitated working up specimens, or indicated additional surgical removal in special cases. CONCLUSIONS: By identification of malignant lesions not detectable with conventional magnification radiography systems, as well as a more exact localisation of suspicious lesions, false negative results may be reduced.

Biopsy↗
PubMed1998

[Spiral CT in arytenoid cartilage dislocation: the optimization of the study parameters with a cadaver phantom and its clinical evaluation].

PURPOSE: To evaluate an optimal scan protocol in a cadaver phantom and its clinical assessment in 40 patients. MATERIALS AND METHODS: In a cadaver larynx phantom helical CT (HiSpeed Advantage; GE, Milwaukee, Wis) was performed with increasing collimation (1-10 mm) and pitch (1.0-3.0). 40 patients with an immobile vocal cord were randomly assigned to undergo CT with a certain protocol. RESULTS: Best resolution was obtained with a collimation of 1 mm and pitch 1. The pitch could be increased up to 2 without losing information. With a collimation of 3 mm and higher, anatomical details were missed. In the patient studies a combination of 1 mm collimation with a pitch of 2.0 showed less motion artifacts than a pitch of 1.0. CONCLUSION: The quality of CT imaging of the arytenoid cartilage depends greatly on the scanning parameters, the compliance of the patients and the mineralisation of the cartilage. For clinical assessment a collimation of 1 mm with a pitch of 2 is recommended. The increase pitch has the advantage of shorter acquisition times and decreased radiation exposure.

Artifacts↗
PubMed1998

[Determination of contour clarity in contrast-enhanced MR angiography: definition and clinical evaluation exemplified by ECG-triggered imaging of the thoracic aorta].

PURPOSE: The sharpness of the vessel contour in 3D contrast-enhanced MR angiography is defined by particular measurements of the signal intensity. To evaluate the facilities of an ECG-triggered data acquisition to optimize the MRA image quality of the thoracic aorta. METHOD: In phantom studies the sharpness of the vessel contour was defined as the distance of the extraluminal signal-minimum to the extraluminal maximum. Afterwards 30 examinations of the thoracic aorta with and without the use of an ECG-triggering were evaluated with regard to the sharpness of the vessel outline. RESULTS: The presented definition of the signal intensity is suitable for objective measurements of the vessel outline. At the level of the ascending aorta, ECG-triggered data acquisition increased the image quality significantly. CONCLUSIONS: An easy, practicable definition enables measurements of the sharpness of the vessel outline. ECG-triggered data acquisition is recommended for optimal visualization, especially of the ascending aorta.

Aorta, Thoracic↗
PubMed1998

Compression device to reduce motion artifacts at contrast-enhanced MR imaging in the breast.

A prototype compression device for a bilateral breast surface coil was manufactured. It was tested in clinical practice (157 patients), and resultant images were compared with those obtained with simple ventral stuffing of the bottom of the coil (181 patients). Compression resulted in reduction of magnetic resonance (MR) examinations with severe motion artifacts from 20 (11%) of 181 examinations to three (2%) of 157 examinations (P = .001). Use of this compression device allowed the subtraction technique at MR imaging in the breast to become an effective method for ensuring more lesion conspicuity.

Artifacts↗
PubMed1998

Storage phosphor direct magnification mammography in comparison with conventional screen-film mammography--a phantom study.

Contact mammography with current photostimulable storage phosphors is hampered by its low spatial resolution. Detail visualization can be improved by geometric magnification radiography which enlarges small details to exceed inherent image noise. This study compares storage phosphor mammography using a dedicated direct magnification system with state-of-the-art conventional screen-film mammography. Storage phosphor direct magnification survey views (1.7x) and spot views (4x) were obtained with a prototype mammography unit providing focal spot sizes of 120-40 microns. Conventional technique screen-film survey views (1.1x) and spot views (1.8x) served as comparison. A contrast detail study and a receiver operating characteristic (ROC) analysis using an anthropomorphic breast phantom with superimposed microcalcifications was performed. Contrast detail resolution in the digital and conventional survey views were equivalent. For the spot views, contrast detail resolution was significantly higher with the digital technique (p < 0.001). ROC analysis of 400 observations demonstrated a significantly higher performance (p < 0.001) with digital images versus conventional screen-film mammograms. The area under the ROC curve (Az) in the digital survey views was 0.76 +/- 0.07 versus 0.59 +/- 0.02 in the conventional technique. In digital spot views, Az was 0.82 +/- 0.07 as compared with 0.66 +/- 0.04 in the conventional spot views. These results suggest that storage phosphor digital mammography in conjunction with direct geometric magnification technique may be superior to conventional screen-film mammography in the detection of microcalcifications.

Breast Diseases↗
PubMed1998

Differences in injection rates on contrast-enhanced breath-hold three-dimensional MR angiography.

OBJECTIVE: The aim of the study was to evaluate the optimization of injection rates with an automatic power injector versus manual injection for contrast-enhanced breath-hold three-dimensional (3D) MR angiography of the abdominal aorta and its branches. SUBJECTS AND METHODS: In a prospective study, 50 patients underwent breath-hold 3D MR angiography (5/2 [TR/TE]; flip angle, 30 degrees) of the abdominal vessels on a 1.5-T system. Each patient received 0.15 mmol/kg of gadopentetate dimeglumine. All patients were randomly assigned to one of five equally sized groups. The contrast bolus was injected manually in group 1, always by the same investigator, who tried to perform a steady injection rate of 2 ml/sec. An automatic injector was used in groups 2-5 with injection flow rates of 0.5 ml/sec, 2 ml/sec, 4 ml/sec, and 6 ml/sec. The start of the MR sequence was tailored individually to the applied volume of contrast material after determination of circulation times by a test bolus. We measured the signal-to-noise and contrast-to-noise ratios as well as the relative vascular enhancement. The visualization of different abdominal vessel segments was independently ranked on a scale of 1-5 (1 = not visible; 5 = excellent visualization) by three reviewers who were unaware of the applied contrast material injection rate. RESULTS: The signal-to-noise and contrast-to-noise ratios of groups 3 and 4 (2 ml/sec and 4 ml/sec, respectively) were significantly (p < .05) higher than the ratios of groups 1, 2, and 5. The average relative vascular enhancement of groups 3 and 4 was significantly higher (p < .05) than the enhancement of all other groups. The contrast bolus applied with a faster injection rate (group 5) did not cover large parts of the K-space, resulting in increased blurring of the vessel contours. The subjective evaluation of large and small diameter vessels showed significantly better results in groups 3 and 4 than in groups 1, 2, and 5. CONCLUSION: The use of an automatic MR power injector proved superior to manual injection of contrast material. The optimal injection rate was 2 ml/sec for 3D breath-hold MR angiography of the abdominal vessels.

Aorta, Abdominal↗
PubMed1998

Magnetic resonance guided localization and biopsy of suspicious breast lesions.

Contrast-enhanced magnetic resonance imaging (MRI) is being used increasingly as a complementary diagnostic modality in breast imaging of preselected patients. The exclusion of multicentricity before surgery and the differentiation between a scar and a carcinoma are well-accepted indications of this method. Problems result when suspicious lesions found with MRI cannot be visualized with mammography or ultrasonography. In these cases, MRI-based guidance systems are needed to guide needle biopsy or allow localization of the lesion before surgery. At our institution, 167 MR-guided interventions (35 percutaneous biopsies and 132 preoperative localizations) have been performed with the use of different types of add-on devices during the past 3 years. Percutaneous biopsy (31 fine needle aspiration and four core biopsies) revealed 24 benign and 8 malignant lesions, 3 biopsies were insufficient. Histologic examination after MR-guided wire localization showed benign findings in 68 lesions (52%) and malignancy in 64 lesions (48%). Technical aspects, experiences, advantages, and disadvantages of our system as well as those of other devices are reported and discussed. MR-compatible equipment for interventions of the breast is demonstrated. In conclusion, we perform MR-guided interventions of the breast routinely in indicated cases at a rate of approximately 3-5% for all patients undergoing diagnostic contrast-enhanced MRI of the breast.

Adult↗
PubMed1998

Arthroscintigraphy in suspected rotator cuff rupture.

AIM: In order to evaluate the diagnostic efficiency of arthroscintigraphy in suspected rotator cuff ruptures this new imaging procedure was performed 20 times in 17 patients with clinical signs of a rotator cuff lesion. The scintigraphic results were compared with sonography (n = 20), contrast arthrography (n = 20) and arthroscopy (n = 10) of the shoulder joint. METHODS: After performing a standard bone scintigraphy with intravenous application of 300 MBq 99m-Tc-methylene diphosphonate (MDP) for landmarking of the shoulder region arthroscintigraphy was performed after an intraarticular injection of 99m-Tc microcolloid (ALBU-RES 400 MicroCi/5 ml). The application was performed either in direct combination with contrast arthrography (n = 10) or ultrasound conducted mixed with a local anesthetic (n = 10). Findings at arthroscopical surgery (n = 10) were used as the gold standard. RESULTS: In case of complete rotator cuff rupture (n = 5), arthroscintigraphy and radiographic arthrography were identical in 5/5. In one patient with advanced degenerative alterations of the shoulder joint radiographic arthrography incorrectly showed a complete rupture which was not seen by arthroscintigraphy and endoscopy. In 3 patients with incomplete rupture, 2/3 results were consistent. A difference was seen in one patient with a rotator cuff, that has been already revised in the past and that suffered of capsulitis and calcification. CONCLUSION: Arthroscintigraphy is a sensitive technique for detection of rotator cuff ruptures. Because of the lower viscosity of the active compound, small ruptures can be easily detected, offering additional value over radiographic arthrography and ultrasound, especially for evaluation of incomplete cuff ruptures.

Adult↗
PubMed1997

[Contrast medium enhanced MR angiography of peripheral blood vessels].

Currently 2D time-of-flight MR angiography (MRA) is most commonly used for the evaluation of the extremities. The major limitation is their susceptibility to signal loss from intravoxel phase dispersion. This leads to overestimation in the grading of stenoses. Further difficulties are motion artifacts and the limited spatial resolution. Phase-contrast MRA is increasingly used. However, further studies are required to verify its diagnostic potential. MRA technology continues to advance rapidly. Stronger gradient fields, shorter echo times and high resolution surface coils are developed. Contrast medium can be applied under standardized conditions with MR compatible power injectors. In phantom studies, the contrast-enhanced gradient echo sequences show reduced phase dispersion, resulting in an improved grading of stenoses. Initial patient studies underline these findings. Contrast-enhanced MR angiography has the potential to replace invasive arteriography in the evaluation of peripheral arterial vessels in the near future.

Arteriosclerosis↗
PubMed1997

[Digital magnification mammography in computed radiography. Initial clinical results].

INTRODUCTION: The combination of direct magnification mammography and computed radiography provides an improvement in spatial resolution of storage phosphor-based digital systems. A clinical study comparing conventional and digital direct magnification mammograms was performed. METHODS: 100 survey mammograms in 1.5-or 1.7-fold magnification and 50 4-fold spot magnification views were obtained with a prototype direct magnification mammography system and a storage phosphor-based digital system. An intraindividual comparison of these with previous conventional radiograms of the same patients was carried out. RESULTS: The diagnostic value of digital survey mammograms using the direct magnification technique is comparable to that of conventional radiograms of the breast, especially with regard to the identification of microcalcifications and lesions and the clinical consequences. Spot magnification views performed with this combination of techniques allowed improvement in the evaluation of microcalcifications. In 15% of cases, diagnostic procedures were adjusted accordingly. CONCLUSION: The combination of the direct magnification technique with digital storage phosphor radiography systems allows the performance of digital mammography by improving the overall spatial resolution. The diagnostic value of digital direct magnification survey mammograms was comparable to that of conventional mammograms. Digital 4-fold spot magnification views improved visualisation of the morphologic aspects of microcalcifications.

Breast Neoplasms↗
PubMed1997

[Direct radiographic magnification mammography with a new microfocus tube. Experimental studies of resolution and radiation exposure].

A recently developed X-ray unit for mammography using microfocal (spot size 0.12-0.05 mm) direct magnification radiography will soon be introduced into clinical practice. Unit arrangement and tube construction have been demonstrated. Mean surface dose was measured using PMMA-phantoms. A dose reduction of up to 50% was obtained in 1.7-fold magnification mammography (full sized views) compared with conventional techniques. The image quality was almost equivalent. However, in comparison with 1.7-fold magnification mammography, a comparable dose range for 4-fold magnifications with the microfocus system was measured with a substantial gain in spatial resolution. These findings satisfy the demands of a modern mammographic unit.

Equipment Design↗
PubMed1997

[MRI-assisted biopsy and localization of the breast].

If suspicious lesions found with MR imaging cannot be visualized by either mammography or ultrasound, MR imaging--based guidance systems are needed to guide needle biopsy or to allow localization of the lesion before surgery. The authors give an overview of the advantages and disadvantages of biopsy devices presented by different working groups. Furthermore, MR-compatible needle equipment for interventions of the breast is demonstrated. The angulation of the needle and the type of sequence are the most important factors for signal loss due to susceptibility. The strategy in special problem cases (multicentricity, bilateral lesions) is discussed. Control MR imaging within the first week after open biopsy is the best way to document the complete excision of a suspicious hypervascularized lesion after MR-guided wire localization. At our institute, percutaneous biopsy (36 interventions) revealed benign findings in 67% and malignant lesions in 25% of cases. Three biopsies were insufficient. Histology after MR-guided wire localization (136 interventions) showed benign findings in 51% and malignancy in 49% of cases. The suspicious lesion was missed by the surgeon in three cases. We perform MR-guided interventions of the breast routinely in indicated cases.

Biopsy, Needle↗
PubMed1997

Prognostic value of contrast-enhanced MR mammography in patients with breast cancer.

The objective of this study was to evaluate the prognostic value of contrast-enhanced MR mammography in patients with breast cancer. A total of 190 patients with breast cancer (37 noninvasive carcinomas, 153 invasive carcinomas) underwent dynamic contrast-enhanced MR mammography preoperatively. Using 1.5-T unit, T1-weighted sequences (2D FLASH) were obtained repeatedly one time before and five times after IV administration of 0.1 mmol gadopentetate-dimeglumine per kilogram body weight. The findings on MR imaging were correlated with histopathologically defined prognostic factors (histological type, tumor size, tumor grading, metastasis in lymph nodes). In addition, immunohistochemically defined prognostic factors (c-erbB-1, c-erbB-2, p53, Ki-67) were correlated with the signal increase on MR mammogram in 40 patients. There was no significant correlation between the findings on MR mammography and the histopathological type of carcinoma, the grading, and the lymphonodular status. Noninvasive carcinomas showed a higher rate of moderate (38 %) or low (27 %) enhancement on MR imaging than invasive carcinomas (6 and 3 %). The results on MR mammography and the results of immunohistochemical stainings did not correlate significantly. Noninvasive carcinomas showed significantly lower enhancement than invasive carcinomas. However, the signal behavior of contrast-enhanced MR mammography is not related to established histopathological prognostic parameters as subtyping, grading, nodal status, and the expression of certain oncogenes/tumor suppressor genes.

Biomarkers, Tumor↗
PubMed1997

[CT-supported virtual intra-arterial endoscopy after stent implantation: phantom studies and the initial clinical results].

PURPOSE: To evaluate the facilities of computed tomographic virtual intraarterial endoscopy (VIE). Imaging of an intravascular stent in a phantom study and clinical assessment in 10 patients. METHODS: The optimal scan parameters for different 3 D reconstructions (MIP, SSD, VIE) were determined in a vessel phantom with intravascular stent. Furthermore, in vitro stenoses were analysed and initial in vivo investigations were performed. RESULTS: The quality of CT-angiography (CTA) depended on the scanning parameters. VIE allowed the reconstruction of the intravascular surface of a stent. CONCLUSION: VIE is a new kind of post-processing CTA reconstruction. It permits the visualisation of the intravascular structure of a stent. In vitro relevant stenoses were correctly detected. First clinical investigations support these results.

Angiography↗
PubMed1997

[Results of a contrast-medium supported 3D MR-angiography in respiratory arrest following optimization of contrast medium bolus].

PURPOSE: Reduction of the contrast material volume by optimised bolus administration during a breath-hold 3D MR angiography and its clinical value. MATERIALS AND METHODS: Breath-hold ultrafast 3D gadolinium-enhanced MR angiography (TR 5 ms, TE 2 ms, FA 20 degrees) of the thoracic and abdominal aorta was performed in 50 patients and correlated with an i.a. DSA. 25 patients (group 1) were examined with a contrast material volume of 40 ml Gd-DTPA and three successive acquisitions at fixed intervals (25, 53 and 81 s) after start of the contrast material injection. Another group of 25 patients (group 2) received only 20 ml Gd-DTPA and the start of the MR acquisition was determined individually by prior evaluation of the contrast material transit times after injection of a test bolus. The signal-to-noise (S/N) and contrast-to-noise (C/N) ratios were compared and a subjective image quality rating (0-3) by three reviewers was achieved in both groups. RESULTS: A total of 37 vascular pathologies were correctly detected by MR angiography compared to i.a. DSA. The grading of stenoses was overestimated in some cases. The S/N and C/N were higher in group 2 (63.2 and 50.1) than in group 1 (58.0 and 38.9). The subjective ratings also showed better results in group 2 (2.76) than in group 1 (2.20). CONCLUSION: The ultrafast gadolinium-enhanced 3D MR angiography allowed a reliable visualisation of the thoracic and abdominal aorta and its branches in a single breath-hold. An optimised examination with a reduced contrast material volume can be achieved by an individual adaptation of the MR acquisition to contrast material administration after measurement of the contrast material transit times.

Aged↗
PubMed1997

[Digital storage phosphor mammography in a magnification technic: experimental studies for spatial resolution and for detection of microcalcifications].

PURPOSE: Since the routine use of storage phosphor systems for mammography has been limited by its inadequate spatial resolution of 5 linepairs/mm, a combination of a magnification mammography technique with storage phosphor plates was investigated to detect microcalcifications. MATERIAL AND METHODS: A new mammography system with a microfocus tube using an anode of 0.05-0.12 mm allowed to obtain survey views of the breast with 1.7x magnification (m), and spot views with 4x magnification. The digital image receptor comprised a high resolution storage phosphor plate. To determine spatial resolution, contrast transfer curves were obtained, and the detection of microcalcifications was investigated by ROC (receiver operating characteristic) analysis. RESULTS: Spatial resolution for digital survey views (m = 1.7) was 8 linepairs/mm and for spot views (m = 4) was 18 linepairs/mm. ROC analysis demonstrated a significantly higher performance of the digital magnification technique compared to the conventional screen-film mammography technique. CONCLUSIONS: The limitations of digital mammography with respect to spatial resolution can be overcome by using a high magnification technique.

Breast Diseases↗