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Biomedical subjects

M Reiser

Publications and source records attributed to M Reiser.

At least 451 records · Page 25Linked to original sources
PubMed1995

Vacuum phenomena in insufficiency fractures of the sacrum.

OBJECTIVE: Insufficiency fractures of the sacrum are found in women who have undergone radiation therapy to the lower abdomen as well as those suffering from osteoporosis of postmenopausal, steroid-induced, or primary biliary cirrhosis-related origin. Increased uptake in bone scintigraphy and osteolytic changes in these fractures can be misinterpreted as bone metastases, leading to unnecessary biopsies and other procedures in the ensuing search for non-existent primary tumor. PATIENTS: In eight female patients averaging 69.4 years of age, insufficiency fracture of the sacrum was diagnosed by computed tomography (CT) and bone scintigraphy. Three underwent a total of five MRI examinations. Malignancy was excluded by histology in two patients and follow-up of at least 6 months in the remainder. Retrospective analysis of CT scans of 13 patients with metastases in the sacrum revealed no vacuum phenomena. RESULTS: In seven of eight patients with insufficiency fracture of the sacrum, vacuum phenomena were shown on CT examination. The gas was localized centrally within the ventral part of the fracture in three patients; gas was located in ten adjacent sacro-iliac joints of six patients. CONCLUSIONS: The vacuum phenomenon may be an incidental finding in osteoarthritis of the sacro-iliac joint, but it has not been previously recognized in IFS. The presence of intra-articular vacuum phenomena in the sacro-iliac joints in combination with a sacral fracture and vacuum phenomena located within the sacral fracture supports a diagnosis of insufficiency fracture or may indeed be the clue by which this diagnosis is established.

Aged↗
PubMed1995

The potential of magnetic resonance imaging (MRI) for quantifying articular cartilage thickness -- a methodological study.

The thickness of patellar articular cartilage was assessed in a cadaveric human knee joint by magnetic resonance imaging. Imaging was conducted at 1.0 T, using three-dimensional gradient-echo sequences. From each of the sequences the total cartilage volume, the size of the articular surface, the mean cartilage thickness and the regional distribution of cartilage thickness were determined by image analysis. These values were then compared with those obtained from anatomical sections. The fat-suppressed FLASH sequence was found to allow the most accurate evaluation of the total volume and the regional distribution of the articular cartilage. Slight underestimation of the cartilage thickness by about 5% may be due to the fact that the calcified layer is not made visible by magnetic resonance imaging. There is, however, a very high degree of similarity between the distribution patterns obtained from the MR images and the anatomical sections. The contrast-to-noise ratios and reproducibility were also highest with the fat-suppressedFLASH sequence. This pulse sequence can therefore be recommended for experimental and clinical use.

Journal Article↗
PubMed1995

[MR mammography at 0.5 tesla. I. Comparison of image quality and sensitivity of MR mammography at 0.5 and 1.5 T].

PURPOSE: To determine whether dynamic MR mammography is possible on midfield systems without loss of diagnostic sensitivity when compared to the standard highfield technique. MATERIALS AND METHODS: 42 consecutive patients were examined twice: Once using the standard dynamic 2D gradient echo technique at 1.5 T; a second examination was performed on a 0.5 T system. For the midfield examinations a 3D sequence with optimized T1 contrast was used to compensate for the shorter T1 relaxation times at 0.5 T. Subtraction images were calculated to improve detectability of enhancing lesions. RESULTS: Image quality was comparable on both systems. Mean enhancement of lesions was higher at 0.5 T/3D as compared to 1.5 T/2D (161% versus 112%). In malignant lesions, enhancement at 0.5 T/3D surpassed that at 1.5 T/2D in 88% of cases; average maximum signal intensity increase of cancers was significantly higher at 0.5 T/3D as compared to 1.5 T/2D (183% versus 108% relative to baseline). One satellite lesion of a recurrent carcinoma was detected on the 0.5 T/3D images only. CONCLUSION: A 3D gradient echo pulse sequence can be used to compensate for the T1 shortening effect of the lower field strength. With a 3D sequence, sensitivity of MRM at 0.5 T is even superior to that of the standard 2D highfield technique.

Adult↗
PubMed1995

[Static and dynamic MR tomography of the pancreas: contrast media kinetics of the normal pancreatic parenchyma in pancreatic carcinoma and chronic pancreatitis].

PURPOSE: We aimed both at improving image quality and diagnostic value of pancreatic MRI by using fast multislice imaging techniques and at demonstrating normal and pathologic signal enhancement in the pancreas after i.v. gadopentate-dimeglumine. METHODS: MR imaging at was performed in 30 patients with suspicion of pancreatic neoplasm or chronic disease and in 15 patients without pancreatic abnormalities. RESULTS: SNR, CNR, mean signal enhancement, and time/signal-intensity curves were calculated. Signal enhancement after i.v. Gd-DTPA averaged 34.4% in neoplasms (n = 14) vs 58.8% in pancreatic tissue not involved by tumour (p < 0.05) in T1-w SE and was also significant in the T1-w GE sequence (p < 0.005). CNR (pancreas vs lesion) and SNR improved significantly (p < 0.005; pancreas: p < 0.001; lesion: p < 0.05) after i.v. Gd-DTPA administration. In patients without pancreatic disease enhancement curves of pancreas demonstrate a rapid signal increase (79.0% after 34 s). Patients with adenocarcinoma or chronic pancreatitis demonstrated flattened signal intensity curves and higher peak signal intensity values (90.1, 111.3% after 68 s). The slope of signal increase of neoplastic tissue was significantly different (p < 0.01) from unaffected parenchyma (48.3% after 51 s, 90.1% after 68 s). CONCLUSION: MR imaging with fast T2-w SE and T1-w SE sequences provides excellent visualisation of the pancreas and adequate conspicuity of pancreatic adenocarcinoma. Following i.v. Gd-DTPA significant enhancement of tumour/parenchyma contrast is found.

Adenocarcinoma↗
PubMed1995

[MR mammography at 0.5 tesla. II. The capacity to differentiate malignant and benign lesions in MR mammography at 0.5 and 1.5 T].

PURPOSE: To determine whether medium field strength (0.5 T) MR mammography is able to differentiate between benign and malignant lesions in the same way as a 1.5 T standard technique. MATERIAL: In 40 consecutive female patients with nodular lesions, examinations were carried out at 1.5 T (2D-FFE, TR/TE/FA 200/3.9/80) and 0.5 T (3D-FFE, 24/3.4/40). RESULTS: There was wide spread of the speed of enhancement of malignant tumours for both techniques (44%-145% with signal increase in the first minute of 42%-189%). In 15 out of 17 carcinomas, the rapidity of uptake and final degree of enhancement after contrast was higher during 0.5 T/3D measurements than it was for 1.5 T/2D images. Fibroadenomas and mastopathies showed similar enhancement characteristics for both techniques. Sharply defined "wash-out" was seen only in malignant lesions; it appeared ten times more frequently in the 0.5 T/3D examinations than at 1.5 T/2D. CONCLUSIONS: The distinction between benign and malignant lesions can be made with more certainty using medium field strength and 3D-FFE sequence than using the 2D high-field standard technique.

Breast↗
PubMed1995

[Vascular, inflammatory and tumorous lesions of the temporal bone and cerebellopontile angle: applications of magnetic resonance tomography].

Advances in high resolution magnetic resonance imaging (MRI) allow the evaluation of the cerebellopontine angle and temporal bone. The purpose of our study was to demonstrate pathological and anatomical aberrations of cerebral arteries in relation to clinical symptoms. The study was carried out on a 1T MR whole body scanner (Impact, Siemens, Erlangen, Germany), using a head coil, a pre- and postcontrast ("Magnevist", Schering, Berlin, Germany) T1-weighted 2D-FLASH sequence and a T2-weighted turbo-spin echo sequence. We examined 22 patients suffering from asymmetric hearing loss, pulse-synchronous tinnitus, hemifacial spasm or facial palsy. The problem of a clear differentiation of meningiomas and acoustic neurinomas by means of MRI is discussed. We identified aberrant AICAs at the cerebellopontine angle in close contact with the V., VII. and VIII. cranial nerve. Inflammatory lesions of the facial and vestibulocochlear nerve were visualised successfully. The potential of the pre- and postcontrast 2D-FLASH sequence for the detection of a wide range of different lesions in the cerebellopontine angle and the temporal bone in MRI of the head was demonstrated.

Arteries↗
PubMed1995

Previously treated, locally recurrent breast cancer: treatment with superselective intraarterial chemotherapy.

PURPOSE: To evaluate the effectiveness of intraarterial infusion chemotherapy (IAC) with mitoxantrone hydrochloride in patients with previously treated, locally recurrent breast cancer. MATERIALS AND METHODS: Thirty-nine women (aged 31-82 years) with recurrent breast cancer underwent superselective IAC (25 mg/m2 mitoxantrone hydrochloride every 24 hours) through the subclavian artery branches after heparin administration. The extent of tumor perfusion was monitored with computed tomography during the intraarterial administration of contrast medium. IAC was repeated one to nine times. Patients had previously undergone radiation therapy (n = 39), surgery (n = 20), or systemic chemotherapy (n = 23). RESULTS: The overall response rate was 77% (n = 30). Eight patients had complete remission. Progression occurred in three patients. Remission was observed in cases of lymph node involvement (n = 9). Seven patients are still undergoing treatment. Side effects were usually moderate. Nine patients died of systemic tumor spread. In 14 patients, distant metastases developed during the first 18 months of treatment. CONCLUSION: IAC is an effective, well-tolerated therapy in patients with locally recurrent breast cancer.

Adult↗
PubMed1995

Reproducibility of quantitative, spirometrically controlled CT.

Quantitative spirometrically controlled computed tomography (with 1-mm-thick sections) was performed twice (with a 5-minute break) in 24 adult patients with pulmonary disease to objectively evaluate parenchymal changes in the lung. Twelve measurements of attenuation were made on apical, carinal, and basal scans (right, left, total of each level, total right, total left, total of all three scans), obtained at 50% vital capacity. Since differences in measurements between the first and second examination were not significant, the method provides highly reproducible results.

Adult↗
PubMed1995

High-resolution activation mapping of basal ganglia with functional magnetic resonance imaging.

We investigated the activation of the putamen and the external and internal division of the globus pallidus in 12 normal volunteers during rapid supination and pronation of their right or left hand, using functional MRI (fMRI). We observed an increase in signal intensity varying from 3.1 +/- 1.2% to 23.4 +/- 2.3% during activation. Activated areas were predominantly contralateral to the moving hand and smaller than 5 mm2. These findings indicate that fMRI allows study of the normal function of basal ganglia and may be of value in the investigation of basal ganglia disorders.

Adult↗
PubMed1995

[Imaging methods in diagnosis and differential diagnosis of breast cancer].

The diagnosis of breast cancer is primarily based on X-ray mammography. Under optimal conditions, a sensitivity of approximately 90% can be achieved. When strict criteria of indication are observed for the additional use of ultrasound or contrast-enhanced MRI, the sensitivity can be increased to about 98%. In addition, the differential diagnosis between benign and malignant lesions can be improved and the rate of biopsies due to false-positive mammograms can be reduced. However, further investigation with ultrasound or MRI of dense or mastopathic breasts that are clinically asymptomatic is not indicated, since it reduces specificity without significant gain of sensitivity.

Breast↗
PubMed1995

[Embolization of bone metastases].

Eighteen patients (11 renal tumours, 3 bronchogenic carcinomas, 4 others) with 24 different bone metastases were embolized for preoperative devascularization (11 x) or for intractable pain (7 x). Metastases were localized in the spine (17 x), pelvis (5 x), and shoulder girdle (2 x). All metastases were hypervascularized. Post-embolization showed no complications. Intraoperative blood loss was minimized to 2100 ml (600 ml-4200 ml). Pain relief was achieved in 6 out of 7 patients. Eight of 18 patients died as a result of underlying diseases (follow-up 7 months).

Aged↗
PubMed1995

[Possibilities of technical and methodological optimization of functional magnetic resonance tomography].

The techniques of in vivo functional magnetic resonance imaging (fMRI) have been established over the past few years. Signal changes resulting from small differences in the magnetic resonance signal caused by variations in the oxygenation state of the venous vasculature are used to map neuronal activity of the brain. While many of the advantages for using MRI for functional neuroimaging are quite obvious (high spatial and temporal resolution, direct anatomic correlation, noninvasiveness), the underlying mechanisms and problems are not fully known. This article focuses on selected topics of fMRI techniques and their problems, such as field strength B0, different types of sequences and their parameters, 2D and 3D data acquisition, different statistical methods and motion artifacts. The authors favor the use of a 1.5 T clinical scanner with EPI capabilities, 2D FLASH sequences with a TR < 60 ms, TE = 30-40 ms, alpha < 20 degrees for high resolution and sensitivity, fMRI and multislice EPI for high temporal and overview and fMRI as well as cross-correlation for post-processing.

Arousal↗
PubMed1995

[The motor hand area. Noninvasive detection with functional MRI and surgical validation with cortical stimulation].

In this study, activation of cortical sites by specific motor tasks (opening and closing of the hand) was examined by fMRI utilizing the blood-oxygen-level-dependent (BOLD) technique. fMRI was employed in five volunteers and in six patients with tumors in the vicinity of the central region. In the patients, the fMRI data and intraoperative cortical mapping were compared. Our results indicate good correlation of these two methods and that there are no significant differences in the localization of the motor hand area.

Adult↗
PubMed1995

[Functional magnetic resonance tomography of the basal ganglia. Use of FLASH sequences for mapping activity with BOLD contrast ane high resolution].

The activation pattern of putamen, internal and external division of globus pallidus was investigated during rapid pronation and supination of the right and left hand in 12 normal volunteers using a FLASH sequence with high resolution for functional magnetic resonance imaging (fMRI) at 1.5 T. The chosen paradigm for motor function led to a signal increase within the basal ganglia between 3 and 23%, depending on the structure and individual subject. In all cases significant activation could be found contralateral to the moving hand. In six cases activation was also found on the ipsilateral side. The activated areas within putamen, internal and external division of globus pallidus were less than 5 mm2. These first results indicate that fMRI studies of basal ganglia are feasible and might be suitable for analyzing basal ganglia disorders.

Adult↗
PubMed1995

[Fatigue fractures of the sacrum in primary biliary liver cirrhosis].

Insufficiency fractures of the sacrum are found in women after radiation therapy of the pelvis and those suffering from postmenopausal and steroid-induced osteoporosis. We report two female patients with insufficiency fractures of the sacrum occurring on the basis of a primary biliary cirrhosis. Both patients had simultaneous Tarlow cysts of the sacrum. The fractures were diagnosed by computed tomography. The findings were sclerotic bone changes, running from the ventral and lateral parts of the lateral mass of the sacrum parallel to the adjacent sacro-iliac joints. These fractures exhibited increased uptake in bone scintigraphy and were responsible for local pain. In one of the patients, the bilateral fractures healed four months after transplantation of the liver was performed.

Female↗