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Biomedical subjects

A Prescher

Publications and source records attributed to A Prescher.

At least 91 records · Page 5Linked to original sources
PubMed1992

[Computed tomographic studies on density kinetics after the bolus injection and infusion of perfluorooctylbromide (PFOB). Animal experimental studies].

We investigated the enhancement of the liver, the spleen, and of induced abscesses and the abdominal vessels after administration of 3 g/kg bodyweight. Perfluorooctylbromide (PFOB) in an animal model. Twenty-one rabbits each received the contrast medium as bolus injection and as slow infusion over half an hour. CT was performed between 2 and 48 hours after contrast medium application. Peak enhancement of the liver, the spleen and the liver abscess membrane was found between 24 and 48 hours after PFOB administration, independently of the application mode. Peak enhancement of the abdominal aorta and the IVC was observed within two hours after bolus injection. In this rabbit model PFOB permits best delineation of the vessels after bolus injection within the first two hours, while CT imaging of the liver, the spleen and the liver abscess membrane is best between 24 and 48 hours after contrast medium application, independent of the injection velocity.

Animals↗
PubMed1992

Computed tomographic enhancement of the liver, liver abscesses, spleen, and major vessels with perfluorooctylbromide emulsion. Influence of dosage and injection velocity in an animal model.

RATIONALE AND OBJECTIVES: Computed tomographic (CT) enhancement of the liver, liver abscess, spleen, and major vessels was investigated between 2 and 48 hours after intravenous administration of perfluorooctylbromide (PFOB emulsion) in an animal model of 63 rabbits. METHODS: Twenty-one animals received 3 g/kg PFOB as a fast bolus injection. Using a slow infusion rate, the same number of animals received either the same dose (3 g/kg) or half the dose (1.5 g/kg). RESULTS: Vascular enhancement was best after bolus injection of 3 g/kg emulsion. The density peak occurred after 2 hours. A continuous enhancement of approximately 100 Hounsfield units (HU) was observed up to 24 hours in the animals receiving 3 g/kg, independent of the injection velocity. A density peak of 70 HU was found 2 hours after the infusion of 1.5 g/kg. The density peak of the liver, the spleen, and the abscess wall was observed 48 hours after emulsion administration in all groups receiving 3 g/kg. The peak was approximately 150 HU for the liver, 400 HU for the spleen, and 150 HU for the abscess wall. In animals receiving only 1.5 g/kg perflubron, the peak density of the abscess wall was 132 HU after 12 hours, approximately 80 HU for the liver between 2 and 48 hours, and approximately 280 HU after 48 hours for the spleen. CONCLUSIONS: PFOB emulsion produces the highest vascular enhancement within the first 2 hours after the bolus injection of 3 g/kg. For spleen and abscess wall imaging, even the relatively low dose of 1.5 g/kg produced a satisfactory enhancement level for a significant length of time, whereas liver enhancement was best after administration of the higher dose.

Animals↗
PubMed1992

Experimental animal model for the evaluation of chemotherapeutical effects on osteosarcoma.

In previous studies radiation-induced osteosarcoma transplanted onto nude rats has been shown to have an extraordinary similarity to human osteosarcoma. In this report the effects of a standard chemotherapeutic regimen on this experimental bone tumor are described. Examination of the histology and of the water content of the tumor confirmed that a high-dose cyclophosphamide monotherapy can cause severe necrosis in the tumor and its seeded lung metastases. A significant decrease in tumor volume of 50% (p < or = 0.01) was provoked and increased the mean survival rate of the treated rats (untreated rats: mean = 39.3 days) significantly to 53.6 days after transplantation of tumor fragments (p < or = 0.01).

Animals↗
PubMed1992

Osteosarcoma of the nude rat. A model for experimental magnetic resonance imaging studies of bone tumors.

A 144cerium-induced osteosarcoma was transplanted to athymic nude rats (Han:rnu/rnu). Nineteen of the tumor-bearing animals were used to demonstrate the characteristics of the osteosarcoma on magnetic resonance imaging (MRI) in comparison with a group of nine animals that had not received any tumor transplant. The tumor-free animals showed homogeneous results in the measurements of their lower legs (T1, 800-898 mseconds; T2, 33-45 mseconds). The osteosarcomas of the tumor-bearing rats were clearly demonstrated and delineated from adjacent structures by MRI at tumor volumes between 0.3 and 7.5 cm3. A significant increase in T1 and T2 relaxation times was found, which corresponded to the increase in tumor volume. T1 relaxation times decreased slightly when tumor volumes reached greater than 5 cm3, whereas T2 relaxation times remained constant at tumor volumes greater than 2.5 cm3. Histologic changes in the structure of the tumors, occurring naturally during their growth, were proven by immersion-fixed sections embedded in paraffin and stained with hematoxylin-eosin. The water content of small and large tumors was determined by lyophilization and heat drying. Both histologic changes and differences in water content were reflected in the variations of relaxation times.

Animals↗
PubMed1991

Stability of osteochondral fragments of the femoral condyle: magnetic resonance imaging with histopathologic correlation in an animal model.

The stability of surgically induced osteochondral fragments of the femoral condyle was examined by magnetic resonance imaging (MRI) using T1- and T2-weighted spin echo sequences in 7 dogs; contrast-enhanced T1-weighted spin-echo sequences were also obtained. Animals were sacrificed between the 34th and 196th day after surgery. MR images were compared with the histopathologic findings. Two loose and five stable fragments were found after injection of contrast medium. With the loose fragments, a well-defined line of high signal intensity between the fragment and the epiphysis showed marked enhancement. Histological examination revealed vascularized granulation tissue at the interface. Stable fragments also showed a similar, but irregularly defined line on plain sequences, but no enhancement after injection of contrast medium; histological examination showed no granulation tissue at the interface but intact bone trabeculae within the completely repaired fracture. Fibrocartilaginous repair at the articular cartilage surface also showed enhancement. Contrast-enhanced MR imaging allowed an exact delineation of the line of separation of unstable osteochondral fragments in this animal model with differentiation from a similar line occurring in stable fragments. However, this interface line in relation to stable fragments could not be explained histologically and probably reflects differences of binding or distribution of protons in healing osteochondral fragments.

Animals↗
PubMed1991

MR-anatomy of infants hip: comparison to anatomical preparations.

The correlation between anatomical preparations and MRI images of the most important structures of newborn hips in coronal and axial orientation was performed in 18 post mortem babies. T1-weighted images present a good differentiation between cartilage, bone, ligaments and surrounding soft tissues. Coronal images give the best opportunity to study the clinically important structures of the roof of acetabulum including the labrum and the ground of the acetabulum. The latter is shown in a more detailed way by MRI than by sonography. Axial images allow additional examinations of the ventral and dorsal parts of the joint. By using both coronal and axial images the exact determination of the centering of the femur head in the hip joint is possible.

Acetabulum↗
PubMed1991

An experimental osteosarcoma of the athymic nude rat.

In this report we describe an experimental osteogenic sarcoma that had been radiation-induced on Sprague-Dawleys by Delbrück in 1980. We transplanted it to 120 athymic nude rats achieving take rates of 100%. The tumor doubling time was 10.5 days. The osteosarcoma on athymic rats thus proliferated extraordinarily well compared to other known models. Pulmonary metastases were demonstrated in 100% of the examined animals. Pathological examinations revealed morphological similarities to human osteosarcoma and no signs of anaplasia.

Animals↗
PubMed1990

Cross-sectional anatomy of the knee.

Frozen knee joints from cadavers were cut into 7 mm slices. The anatomical structures of representative slices were described in detail in order to provide us with information of the topography of the anatomical structures as possible. The detailed description is thought to be helpful for the interpretation of MR images of the knee joint.

Humans↗
PubMed1990

The differential diagnosis of isolated ossicles in the region of the dens axis.

2 osteological specimens of the atlanto-occipital region with accessory ossicles sitting on the dens axis are described. Considering the anatomical and radiological literature, the differential diagnosis of isolated accessory ossicles in the region of the dens axis is discussed (e.g. os odontoideum, ossiculum terminale BERGMANN persistens, ossifications of the ligamentous apparatus).

Aged↗
PubMed1989

[NMR tomography of the cartilage structures of the knee joint with 3D-volume imaging combined with a rapid optical-imaging computer].

MRI is of increasing importance as a noninvasive method for the investigation of abnormalities in the knee. 2-D spin-echo sequences were compared with 3-D gradient-echo sequence using normal and cadaver knee joints. 3-D imaging using a fast computer was found to provide significantly improved diagnostic information concerning the cartilage when compared with a 2-D spin-echo techniques. The important advantages are: sections of less than 1 mm., reconstruction in any required plane, which can be related to the complex anatomy of the knee joint, and very good distinction between intra-articular fluid, fibrocartilage and hyaline cartilage.

Cadaver↗
PubMed1989

[MRT of the knee joint cartilage using 3D volume imaging in combination with a fast image processor].

From the knees of healthy persons and cadavers 2D-spin-echo-sequences were compared to 3D-gradient-echo-sequences (FLASH, FISP). We were able to show that 3D-volume-imaging, combined with image processing on a fast computer, is superior to 2D-spin-echo-imaging. The advantages are: slice thickness lower than 1 mm, secondary reconstruction in any desired plane, good contrast between intraarticular fluid, the meniscus and the hyaline cartilage. For the practical application of 3D-volume-imaging resulting in multiple images the secondary reconstruction and post processing of the large numbers of images with an image processing computer is necessary.

Cartilage, Articular↗
PubMed1988

[Hyaline articular cartilage in MR tomography of the knee joint at 1.5 T].

MRI is a new method for imaging the knee joint. There is still some uncertainty regarding the extent and the signal from hyaline articular cartilage. MRI images were therefore compared with anatomical and histological preparations of the knee joint and the difference between MRI and the anatomical sections have been determined. It was shown that demonstration of hyaline cartilage was obscured by an artifact. Further investigations are required to determine the cause of this artifact and to achieve accurate imaging of hyaline cartilage by MRI.

Cadaver↗
PubMed1988

[Metastyloid, parastyloid and secondary pisiform bones].

3 rare cases of accessory osseous carpal elements are described and compared with similar cases of the literature. Especially a case of a well developed metastyloid bone combined with a parastyloid bone is remarkable. Furthermore a very regressive metastyloid bone and, appearing in another hand, a pisiforme secundarium is described.

Aged↗
PubMed1987

[Processus trochlearis tibiae Hyrtl or osteochondroma?].

A case of a well developed exostosis at the medial proximal site of the left tibia from a 74 year old male is described. The interpretation of the osseous spur as an exostosis (Osteochondroma) is contrasted with Hyrtl's explanation as a trochlear process.

Aged↗
PubMed1987

[Rare muscle variations of the forearm].

An accessory twin-bellied muscle in both forearms of a male was observed. On the right side, the accessory muscle originated from the main muscle belly of the superficial flexor muscle of the fingers and inserted on the index finger tendon of the superficial muscle. On the left side, the accessory muscle belly originated from the medial epicondyle of the humerus and inserted on the index finger tendon of the superficial muscle. A further accessory muscle belly originated from the distal muscle belly and joined with the lumbrical muscle just before its insertion on the dorsal aponeurosis. The functional effects are discussed and compared to a similar case in literature.

Forearm↗
PubMedDate not supplied

Experimental hyaline cartilage lesions: two-dimensional spin-echo versus three-dimensional gradient-echo MR imaging.

The value of magnetic resonance (MR) imaging, with two-dimensional (2D) spin-echo and FISP (fast imaging with steady-state precession) and FLASH (fast low-angle shot) three-dimensional (3D) gradient-echo sequences, for the detection of hyaline cartilage defects of the femoral condyle and the tibial plateau, was investigated in an animal model. In eight dogs, the anterior cruciate ligament was transected in one knee joint, resulting in rapid development of osteoarthritis with degeneration of the hyaline cartilage. At autopsy, 24 cartilage lesions were found, which were classified into four grades. The overall detection of cartilage lesions with MR imaging was poor. Only five of the 24 lesions were visible on 2D spin-echo images, while 11 of 24 were visible on 3D FISP images and 15 of 24 were seen on 3D FLASH images. The best results were obtained in advanced stages of cartilage degeneration, involving ulceration and complete abrasion of the cartilage layer. Signal loss or signal intensity increase in the cartilage layer was seen inconsistently in grades 3 and 4 degeneration. In this animal model, 2D spin-echo imaging was inadequate for the diagnosis of hyaline cartilage lesions, while 3D gradient-echo imaging permitted satisfactory diagnosis in only grade 4 cartilage disease.

Animals↗
PubMedDate not supplied

Dynamic MRI of a hypovascularized liver tumor model: comparison of a new blood pool contrast agent (24-gadolinium-DTPA-cascade-polymer) with gadopentetate dimeglumine.

We evaluated the enhancement properties of a new blood pool contrast agent (24-gadolinium-diethylenetriamine pentaacetic acid [Gd-DTPA]-cascade-polymer) in comparison with gadopentetate dimeglumine in 24 rabbits with an experimentally induced VX-2 liver tumor. Dynamic MRI of the liver was performed before, immediately after, and within 15 seconds to 30 minutes after contrast agent administration. Relative signal intensities and contrast-to-noise ratios (CNRs) of both agents were evaluated. After blood pool agent administration a significantly higher CNR between liver and tumor was observed within 2 to 30 minutes after injection as compared with the CNR after gadopentetate dimeglumine. Within 4 to 30 minutes after injection of gadopentetate dimeglumine, the relative signal intensities of tumor were significantly higher than after administration of the blood pool agent. In conclusion, the new blood pool contrast agent demonstrated a significantly better CNR of the experimental hypovascularized liver tumor than gadopentetate dimeglumine.

Animals↗