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M Reiser

Publications and source records attributed to M Reiser.

At least 685 records · Page 38Linked to original sources

MR angiography of congenital heart disease: value of segmented two-dimensional inflow technique and maximum-intensity-projection display.

Magnetic resonance (MR) angiography of the cardiovascular system was evaluated in 41 patients with congenital heart disease by using a two-dimensional (2D) inflow technique based on a magnetization-prepared gradient-echo pulse sequence with segmented k-space data acquisition and electrocardiographic gating at 0.5 T. Inversion and saturation prepulses were used to suppress stationary tissue and enhance intravascular signal. Presaturation slabs were applied where certain vascular structures had to be suppressed. Sequence parameters were optimized by evaluating signal intensity and contrast characteristics for various flip angles and inversion and saturation delay times. The heart and intrathoracic vasculature were encompassed with 40-50 overlapping sections. Both 2D angiograms and maximum-intensity-projection images were evaluated. Combining data sets acquired in the sagittal and transverse orientations provided the most satisfactory information about the pulmonary arteries. The highest signal-to-noise ratios were obtained with a flip angle of 65 degrees and short prepulse delay times. Two-dimensional MR angiography can provide useful diagnostic information but requires a thorough understanding of in-plane and hemodynamically induced signal intensity changes.

Aorta↗

Single-shot T1- and T2-weighted magnetic resonance imaging of the heart with black blood: preliminary experience.

PURPOSE: To implement and evaluate two robust methods for T1- and T2-weighted snapshot imaging of the heart with data acquisition within a single heart beat and suppression of blood signal. METHODS: Both T1- and T2-weighted diastolic images of the heart can be obtained with half Fourier single-shot turbo spin echo (HASTE) and turbo fast low-angle shot (turboFLASH) sequences, respectively, in less than 350 ms. Signal from flowing blood in the ventricles and large vessels can be suppressed by a preceding inversion recovery preparing pulse pair (PRESTO). Fifteen volunteers and five patients have been evaluated quantitatively for signal-to-noise ratio (SNR) contrast-to-noise ratio (CNR) and flow void and qualitatively for image quality, artifacts, and black-blood effect. RESULTS: Both PRESTO-HASTE and PRESTO-turboFLASH achieved consistently good image quality and blood signal suppression. In contrast to gradient-echo (GRE) echo-planar imaging techniques, (EPI) HASTE and turboFLASH are much less sensitive to local susceptibility differences in the thorax, resulting in a more robust imaging technique without the need for time-consuming system tuning. Compared to standard spin-echo sequences with cardiac triggering. HASTE and turboFLASH have significantly shorter image acquisition times and are not vulnerable to respiratory motion artifacts. CONCLUSION: PRESTO-HASTE and PRESTO-turboFLASH constitute suitable methods for fast and high-quality cardiac magnetic resonance imaging (MRI).

Blood↗

Diagnosis of adnexal torsion in the third trimester of pregnancy: a case report.

The diagnosis of adnexal torsion is difficult to establish on the basis of symptoms, physical findings, or radiologic techniques. If possible, in pregnancy the diagnostic workup should avoid any risk of drug administration, and the indication for a surgical intervention needs to be severe. Between 10% and 20% of ovarian torsions are associated with pregnancy, but adnexal torsion in the third trimester is rare. We present the case of a 22-year-old female presenting with a sudden onset of severe right lower quadrant abdominal pain associated with nausea and vomiting. The presumptive diagnosis was appendicitis. Transvaginal sonography showed some free fluid in the pouch of Douglas, but could not define the accurate diagnosis. In transabdominal ultrasound, a predominantly hyperechogenic mass containing small cysts was found in the right lower abdomen. No blood flow within the mass was detected with color and power Doppler sonography. With ultrasound, the anatomic relation of the mass could not be precisely identified. Magnetic resonance imaging clearly delineated the mass, which was due to enlargement of the right ovary, with predominately hyperintense signal containing small areas with hypointense lesions in T2-weighted images, a potential sign of hemorrhagic infarction. The mesovarium was hyperintense in T2-weighted images and also enlarged. The left ovary seemed to be normal. Due to the displacement of the ovaries in the second and third trimesters, the diagnostic workup is very largely restricted when using transvaginal ultrasound. Especially in pregnancy, it is mandatory to obtain a reliable diagnosis to reduce any risk to the fetus. Our case report indicates that the combination of magnetic resonance imaging and Doppler sonography fulfills these requirements and allows for accurate and fast diagnosis of adnexal torsion.

Adnexal Diseases↗

Transcatheter coil embolization of an aneurysm of the pancreatico-duodenal artery with occluded celiac trunk.

We report on a case of a wide-necked aneurysm of the pancreatico-duodenal artery with occlusion of the celiac trunk in an asymptomatic patient. The aneurysm was considered to be at high risk of rupture. Successful embolization after interdisciplinary consultation was followed with color-coded duplex ultrasound (CCDS) demonstrating significant flow reduction. Three weeks later CCDS and angiography demonstrated exclusion of the aneurysm and a patent arterial supply of the liver and spleen fed by superior mesenteric artery (SMA) collaterals. The patient has done well so far, without major adverse clinical events or evidence for tissue necrosis of the liver, pancreas or spleen. Discussion of the case and review of the literature indicate that transcatheter embolization is the therapy of choice even in complicated cases.

Aged↗

Treatment of secondary stent-graft collapse after endovascular stent-grafting for iliac artery pseudoaneurysms.

We report the case of a patient who developed an asymptomatic pseudoaneurysm in the left external iliac artery after transplant nephrectomy. The pseudoaneurysm most probably arose as a suture aneurysm from the external iliac artery after removal of the graft renal artery. Obviously we can not exclude the possibility it was a true aneurysm, although this seems much less likely. The pseudoaneurysm was detected during a routine CT scan and was treated interventionally with a stent-graft. One month later the asymptomatic patient underwent a vascular ultrasound examination including color Doppler, power Doppler, and B-flow as a routine control. An endoleak with collapse of the stent-graft was diagnosed. There was no evidence of stent infection. At a reintervention, the pseudoaneurysm was successfully treated using two uncovered Palmaz stents at the proximal and distal edge of the stent graft. Peri- and post-interventional ultrasound and CT angiography confirmed the exclusion of the aneurysm without an endoleak.

Adult↗

Contrast-enhanced ultrasound in detection and follow-up of an infrarenal abdominal aortic aneurysm with aorto-caval fistula and endovascular treatment.

An aorto-caval fistula is a rare complication of a symptomatic or ruptured infrarenal aortic aneurysm having a frequency of 3-6%. Patients typically present with clinical signs of diffuse abdominal pain associated with increasing venous congestion and tachycardia, rapid cardiopulmonary decompensation with acute dyspnea, and an audible machinerylike bruit. Perioperative mortality is high, ranging from 20% to 60%. We report a case of an endovascular aortic repair in a patient with a symptomatic infrarenal aortic aneurysm and an aorto-caval fistula. Contrast-enhanced ultrasound seems to be a promising new diagnostic option for the diagnosis and preoperative treatment planning for patients with abdominal aortic aneurysms with rupture into the inferior vena cava. It is in addition to computed tomography angiography. It might allow a more rapid and noninvasive diagnosis, especially for patients in intensive care because of its bedside availability. Because the examination is dynamic, additional information about blood flow between the aorta and inferior cava vein can be evaluated.

Angioplasty↗

Interventional radiological procedures in impaired function of surgically implanted catheter-port systems.

PURPOSE: System-related complications in surgically implanted catheter-port systems (CPS) for intraarterial (i.a.) chemotherapy are well known. In most cases of complications, the treatment must be interrupted and the catheter-port system must be repaired surgically. We describe microinvasive interventional radiological procedures to correct some dysfunctions of CPS. METHODS: Five patients with repetitive dysfunction of CPS were treated with interventional techniques. Two patients presented with perfusion impairment, one patient had a pseudoaneurysm of the hepatic artery, and two patients presented with catheter displacement. Radiological interventions included mechanical recanalization with a guidewire, vascular stenting, and correction of catheter dislocation with a goose-neck snare. RESULTS: In all cases, correct function of the CPS was restored. No intervention-related complications occurred and surgery was avoided. Chemotherapy could be continued for a period of 4--10 months. CONCLUSION: For some system-related complications, minimally invasive radiological interventions can be used to restore the function of CPS for i.a. chemotherapy.

Aged↗

Unilateral centrifugation of the otoliths as a new method to determine bilateral asymmetries of the otolith apparatus in man.

Ten healthy subjects were eccentrically rotated with constant speed on a Barany chair. Setting of a luminous line (LL) to the subjective vertical and ocular counter-roll (OCR) were evaluated. During eccentric position rotation subjects consistently reported illusory rotation and set the LL to an angle correlating to centrifugal force. At the same time an OCR of opposite direction was measured. In one patient, labyrinthectomized on the right side, only counterclockwise rotation of the luminous line was observed. Differences between "inner" and "outer" eye were evident for luminous line settings and OCR in some subjects. The results indicate that eccentric rotation is a valuable method to test for bilateral otolith asymmetries. The method can be applied to preflight tests of astronaut candidates for susceptibility to spacesickness. It is also offered for clinical evaluation of unilateral otolith impairments.

Adult↗

Intracerebroventricular administration of insulin attenuates retrieval of a passive avoidance response in rats.

The effect of intracerebroventricularly applied insulin on one-trial learning passive avoidance behaviour has been studied in rats. Treatment with 10.3 pmole insulin 1 hr before the 24 hr retention test attenuated passive avoidance behaviour at both the 24 hr and 48 hr retention trials. The data suggest that insulin may play a role in processes relating to the retrieval of information stored in the brain.

Animals↗

[MRI-based 3-D analysis of the glenohumeral translation in patients with shoulder instability].

AIM: Until now, pathological translation of the glenohumeral joint could not be assessed three-dimensionally and in functionally important arm positions in the living. The objektive of this study was therefore to develop an MR-based technique for determining the three-dimensional glenohumeral translation in functionally relevant positions in vivo. METHOD: In an open MR scanner both shoulder joints of 5 volunteers with an unilateral traumatic instability were examined in different positions of abduction and rotation. After semiautomatic segmentation, 3D reconstruction of the bony structures of the shoulder girdle was performed and the center of mass of the glenoid cavity was determined and used as reference point. In a virtual reality, the midpoint of the humeral head was assessed and its position relative to the center of mass of the glenoid cavity was calculated. RESULTS: At 30 degrees of abduction, in both shoulders, the humeral head was positioned inferior and posterior relative to the glenoid cavity (healthy: 0.42 +/- 1.1 inf., 0.75 +/- 1.0 mm post.; unstable: 1.31 +/- 0.87 mm inf., 0.51 +/- 1.28 mm post.) The maximal translation (to anterior and inferior) was observed both on the healthy side (mean 1.0 mm, max. 1.8 mm) and in the unstable shoulders (mean 2.5 mm, max. 4.6 mm) with the arm in 90 degrees of abduction and external rotation, thus being 1.7 to 2.5 times higher in the pathological shoulders. CONCLUSIONS: With this technique the glenohumeral translation can be quantified three-dimensionally in functionally important positions and without projectional artefacts. In the future, this method can be applied to patients with different entities of shoulder instability.

Adolescent↗

[An MR-based technique for determination of the subacromial space width in subjects with and without shoulder muscle activity].

INTRODUCTION: The occurrence of the impingement syndrome of the shoulder is dependent on muscle activity and arm position. However, the current radiological workup is based on conventional radiographs, CT or MRI obtained at 0 degree of abduction and at muscular relaxation. The objective of this study was the development of a technique for simultaneous visualization of the humerus, scapula, clavicle and their relationship to the M. supraspinatus--in different arm abduction positions with and without muscle activity--as well as the determination of the minimal acromio-humeral distance. METHOD: The shoulder joints of 8 volunteers were examined in an open MRI system at 60 degrees, 90 degrees and 120 degrees of abduction, using a T1 weighted 3D gradient echosequence. Forces of 10 N were applied at the distal humerus. After 3D reconstruction, the acromio-humeral distance was computed with Euclidian distance transformation. RESULTS: With increasing abduction, the acromio-humeral distance decreased significantly (p < 0.05), but the distance vector was localised laterally to the M. supraspinatus at 120 degrees. With muscle activity a reduction of the subacromial space of 29% (p < 0.05) occurred at 60 degrees whereas at 120 degrees a 51% (p < 0.05) increase was noted. At 90 degrees, no significant difference was observed. CONCLUSION: With the technique presented it is possible to determine the subacromial space width in different arm positions independent of the specific section orientation, with and without muscle activity. The method can be used as a basis for biomechanical investigations and for the clinical diagnosis of impingement syndrome.

Adult↗

[Giant cell tumor of bone].

This retrospective study analyses 67 patients with 69 giant cell tumors of bone staged according to the Surgical Staging System of benign and malignant lesions of Enneking (1980, 1986). A significant correlation between Stage 2 and Stage 3 benign lesions in respect to local recurrence as well as between the therapeutic procedures and recurrence was found. Intralesional excision with temporary acrylic cement implantation showed to be the preferable initial treatment of these tumors. Special attention to surgical staging, surgical techniques and a supervised rehabilitation program minimize the incidence of recurrence and at the same time giving am maximum of joint function.

Adolescent↗

[Giant cell tumor of bone. An analysis of 69 cases].

1. The tumor stage of the giant cell tumor is an indicator for the prognosis and the need for adjuvant therapy. 2. Intralesional excisions without an adjuvant result in high rates of recurrence. 3. Polymethyl methyl acrylate (PMMA) largely prevents recurrences, provides stability and makes early functional treatment possible. 4. Broad excisions should only be performed in bone which is dispensable. 5. Recurrences frequently manifest themselves by pain. They can be removed intralesionally, as in primary therapy.

Adolescent↗

[Clinical significance of computerized tomography of the posterior area of the foot].

Computertomographic examinations of the hindfoot in the frontal and horizontal view will show us morphological findings, which we could not see with conventional X-ray-technique. Out of these findings we are able to control our operative reconstruction as well as late changes in bone healing. The horizontal view will show us the osseous structures of the talus and calcaneus as well as of the navicular and cuboid bone, as it is necessary for preoperative evaluation of the hindfoot.

Ankle Joint↗