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Biomedical subjects

M F Müller

Publications and source records attributed to M F Müller.

At least 19 recordsLinked to original sources
PubMed2004

[Neurodevelopment of extremely low birthweight infants born in Erasmus Hospital between 1992 and 2001].

Survival of extremely low birth weight infants has dramatically improved in the last decade of the twentieth century. The objective of our study was to evaluate the neurological evolution of the surviving infants because frequent motor, sensitive and psychological disturbances are related. Prospective, longitudinal study in a population of newborns, nursed in our neonatal intensive care unit and born between 1992 and 2001 with less than 1.000 g and/or less than 28 weeks of gestational age (GA). Neurological assessment of outcome was made using the neurodevelopmental score (O.M.S. 1988) at 6, 9, 12, 18, 24 and 36 months. Neurological follow-up every year and neuropsychological testing at 3, 5 and 8 years. Only children with at least 2 years of follow-up were included. The children were grouped in 3 categories: M (major neurological handicap), m (minor neurological handicap), N (normal neurological outcome). To evaluate the evolution with time, we compared the results from the first period (1992 to 1996) to the second part of this decade (1997 to 2001). Mortality fell from 38% (27/70) in the first period (1992-1996) to 18% (8/44) in the second one (1997-2001) (p = 0.02) including neonates of less than 25 weeks GA. Neurodevelopmental status improved and severe brain lesions decreased (25% with intraventricular haemorrhage III & IV and cystic periventricular leukomalacia versus 6% in the second period) (p = 0.017). Major handicap fell from 26% (9/34) to 16% (5/31) and normal neurological evolution raised from 15% (5/34) to 48% (15/31) (p = 0.013). With the survival of newborns less than 28 weeks, the severe ocular complications increased: 6% (5/79). In conclusion, mortality and quality of life have significantly improved in the past 10 years in our service. Severe brain lesions have decreased under a better multifactorial management. Nevertheless when the gestational age of the surviving babies diminishes, ocular sequelae increase. We still think that prematurity remains a burden for the child, his family and the society.

Brain↗
PubMed2001

[Papillary hemodynamics in patients with normal pressure glaucoma and hemorrhage of the optic papilla circumference].

BACKGROUND: Optic disc hemorrhages in patients with normal-pressure glaucoma (NPG) are usually regarded as a sign of vascular dysfunction and as an indicator for glaucoma damage progression. METHODS: Optic nerve head blood flow was measured in 21 patients suffering from NPG with acute optic disc hemorrhages by scanning laser Doppler flowmetry at various locations of the optic disc. Intraocular pressure and mean deviation of the visual field were also monitored. Two groups served as control: 21 patients with NPG matched for age, sex, and stage of the disease and in addition the contralateral eye without any hemorrhages. RESULTS: Optic nerve head blood flow as a mean of several locations was significantly lower in eyes with optic disc hemorrhages than in controls and differed significantly from the contralateral eye. CONCLUSION: Optic nerve blood flow was lower in NPG eyes with optic disc hemorrhages than in the contralateral eye and in controls.

Aged↗
PubMed1999

Mural aortic thrombi: An important cause of peripheral embolization.

PURPOSE: Arterial thromboembolism in patients with an unknown source of embolization is still associated with significant morbidity and mortality. The advent of transesophageal echocardiography (TEE) and magnetic resonance imaging (MRI) and the more frequent use of computed tomography (CT) have led to the identification of mural aortic thrombi (MAT) as a source of distal embolization in a much higher proportion of patients than previously appreciated. The incidence, diagnosis, and treatment of patients with MAT is reported. METHODS: In a prospective study, from January 1996 to December 1998, 89 patients with acute embolic events underwent an extensive diagnostic workup, consisting of TEE, CT, or MRI, to detect the source of embolization. Patients in whom the heart (n = 51), occlusive aortoiliac disease (n = 16), or aortic aneurysms (n = 12) was identified as the source of embolization were excluded. RESULTS: Five female and three male patients, with a median age of 63 years (range, 35 to 76 years), with bilateral or repetitive embolic events resulting from MAT were identified, representing 9% of all patients with arterial thrombembolism. All patients had several risk factors for atherosclerosis, but only one young patient had a single risk factor that promoted thrombosis. Successful percutaneous catheter aspiration embolectomy was performed in six patients. The remaining two patients underwent surgical thromboembolectomy. A below-knee amputation had to be performed in two patients, thus representing a morbidity of the primary treatment of 25%. MAT of equal value were detected in the ascending (n = 1) and thoracic aorta (n = 3) by means of TEE, CT, or MRI. MAT in the abdominal aorta (n = 4) were identified by means of CT and MRI. Surgical removal of MAT was performed in seven patients by means of graft replacement of the ascending aorta (n = 1), open thrombectomy of the descending aorta (n = 2), and thrombendarterectomy of the abdominal aorta (n = 4), without intraoperative or postoperative complications. No recurrence of MAT occurred during a median follow-up period of 13 months (range, 4 to 24 months). CONCLUSION: MAT represent an important source of arterial thrombembolism. A diagnostic workup of the aorta, preferably by means of CT or MRI, should be performed in all patients in whom other sources of embolization have been ruled out. The ideal therapeutic approach to these patients still awaits prospective evaluation. However, based on our experience, MAT can be successfully treated with a definitive surgical procedure in selected patients, with low mortality and morbidity.

Adult↗
PubMed1999

Evaluation of coronary bypass flow with color-Doppler and magnetic resonance imaging techniques: comparison with intraoperative flow measurements.

OBJECTIVES: After coronary artery bypass surgery, patency and flow assessment is based on invasive methods such as angiography and intravascular ultrasound or flow wire techniques. The aim of the study was to compare intraoperative transit time flow measurements of coronary bypass grafts with early postoperative color-Doppler and MR-imaging assessment. METHODS: In 22 patients (62+/-8.5 years) undergoing elective coronary bypass surgery the flow was measured in all internal mammary artery grafts (IMA) and saphenous vein grafts using the transit time flow technique. Postoperatively (days 5-7) all patients had a color-Doppler IMA graft assessment followed by a MR-angiography and flow measurement (navigator echo phase contrast technique with and without contrast bolus application) to determine patency and graft flow. RESULTS: Data are expressed as the mean +/- SD). (1) In all patients the left IMA graft to the left anterior descending coronary artery (LAD) could be identified and flow could be assessed with both color-Doppler and MRI. Venous grafts could only be visualized by MRI. The use of an intravenous contrast bolus enhanced the visualization of coronary artery bypass grafts. (2) The mean IMA to LAD flow was 33+/-17 ml/min intraoperatively by transit time and postoperatively 36+/-25 ml/min by MR respectively 66+/-54 ml/min by color-Doppler technique. (3) The systolic/diastolic flow ratio was 0.44+/-0.12 intraoperatively and 0.43+/-0.17 postoperatively by MR respectively 0.67+/-1.0 by color-Doppler. (4) A statistically significant correlation could be demonstrated between intraoperative transit time and postoperative MR flow measurements (r = 0.57; P < 0.04), whereas the correlations to color-Doppler flow were poor. Postoperatively MR and color-Doppler showed a good correlation of systolic/diastolic flow ratio (r = 0.88; P < 0.008). CONCLUSIONS: The color-Doppler method during echocardiography and MR-imaging are useful non-invasive techniques to visualize postoperative IMA grafts for patency assessment. The quantification of IMA flow is still difficult with either technique, but MR flow measurements showed the best correlation to the intraoperatively measured transit time flow. The MR technique is the most promising non-invasive method for postoperative evaluation of coronary bypass grafts, since it allows visualization and reliable flow quantification.

Blood Flow Velocity↗
PubMed1998

Can the IVIM model be used for renal perfusion imaging?

OBJECTIVE: Renal perfusion imaging may provide information about the hemodynamic significance of a renal artery stenosis and could improve noninvasive characterization when combined with angiography. It was proposed previously that diffusion sequences could provide useful perfusion indices based on the intravoxel incoherent motion (IVIM) model. Owing to motion artifacts, diffusion imaging has been restricted to relatively immobile organs like the brain. With the availability of single-shot echo-planar imaging (EPI) our purpose was to evaluate the IVIM model in renal perfusion. METHODS AND MATERIAL: Eight volunteers underwent diffusion-sensitive magnetic resonance (MR) imaging of the kidneys using a spin echo (SE) EPI sequence. The diffusion coefficients determined by a linear regression analysis and fits to the IVIM function were calculated. RESULTS AND CONCLUSION: Our preliminary experience does not support the possibility of obtaining perfusion information using the IVIM model in the kidneys.

Artifacts↗
PubMed1998

Assessment of cardiac rejection by MR-imaging and MR-spectroscopy.

BACKGROUND: Detection of cardiac rejection is a major problem in cardiac transplantation. The gold standard is, and remains, endomyocardial biopsy. PURPOSE: Evaluation of MR-imaging and MR-spectroscopy for detection of cardiac rejection. METHODS: Orthotopic cardiac transplantation (HTX) was performed in 13 pigs (body weight 30 kg). All animals obtained immunosuppressive (triple) therapy for 1 week after the operation. Thereafter immunosuppression was stopped to induce cardiac rejection. MRI and MRS (1.5 Tesla General Electrics Signa) were performed pre- and post-operatively on days 10, 17, 24 and 31. The degree of rejection was determined post-operatively using endomyocardial biopsy (Texas grading score). RESULTS: (1) MR-imaging: LV function remained unchanged after HTX. LV mass increased (+42%; P < 0.05) with cardiac rejection. (2) MR-spectroscopy: a marked reduction in the ratio of phosphocreatine and adenosine triphosphate, respectively, to inorganic phosphate was observed in the rejecting hearts. (3) Histologic grading confirmed cardiac rejection after stopping immunosuppression. The Texas score was 5.7+/-0.8 at autopsy. CONCLUSIONS: MR-imaging and MR-spectroscopy allow the detection of changes associated with cardiac rejection. Both techniques are correlated with histologic rejection. However, endomyocardial biopsy remains the gold standard for reliable detection of cardiac rejection.

Adenosine Triphosphate↗
PubMed1998

[The significance of magnetic resonance venography in the pre-interventional clarification of a malignant superior venous obstruction].

PURPOSE: Comparison between peripheral digital subtraction venography (DSV) and magnetic resonance venography (MRV) in planning for stent placement in malignant superior central venous obstruction. METHOD: 19 patients with malignant central vein obstruction were examined by DSV (n = 19) and MRV (n = 19). For each patient 12 segment-vessel evaluation was performed to review for obstruction and then compared with the gold standard--selective catheter phlebography--performed at the time of stent insertion. Additionally, tumor extension and collateral venous outflow was noted. RESULTS: Sensitivity, specificity, and accuracy amounted to 92%, 96%, and 95% for DSV and 98%, 100%, and 100%, respectively for MRV. The McNemar test revealed a significance between MR venography and DSV. CONCLUSIONS: With regard to planning of stent placement, a more exact evaluation was possible with MR venography than with DSV. Thus, MR venography can replace DSV as the method of choice for clarifying malignant superior central vein obstructions prior to stent placement.

Adult↗
PubMed1998

[The focus in neonatology].

During the last years, neonatology has greatly improved. In the last decade, mortality and morbidity have decreased: mortality from respiratory failure of prematurity has decreased from 22% to 12%, mortality of the very low birthweight infants under 1000 g fell from 56% to 35% and mortalities related to asphyxia have diminished from 21% to 12% and to malformations from 33% to 28%. Prematurity is now the first cause of neonatal mortality. During this period, the number of babies under 1000 g has increased 4-fold and the number of multiple births increased more than 2-fold from 3% to 7% of the live births of our hospital. Attitudes towards the premature infant have changed, especially towards the extremely small (called the micropremies). The number of disabled children has increased in parallel with the better survival of the very immature newborns who till recently were not resuscitated.

Asphyxia Neonatorum↗
PubMed1996

[Magnetic resonance angiography of the carotid artery: effect of short and ultra-short echo times].

PURPOSE: To evaluate the influence of short and ultrashort echo times (TE) on the magnetic resonance (MR) signal in the carotid sinus and in carotid artery stenoses. MATERIAL AND METHODS: High resolution gradient-echo sequences without and with flow compensation using TE's ranging from 1.5 to 8.0 ms were compared on phantoms, eight healthy volunteers, and 10 patients with moderate and severe carotid artery stenoses. RESULTS: MR sequences with shortest TE's provided the best visualisation of stenotic regions in the carotid sinus and demonstrated a substantial reduction of signal loss due to spin dephasing in both phantom and patient studies. This was made possible using an improved gradient system with higher gradient strengths and shorter rise times with lower acquisition bandwidths and better signal-to-noise ratio. CONCLUSION: MR sequences with short and ultrashort TE's enable a better definition of the stenotic region and therefore guide adequate therapeutic decisions.

Adult↗
PubMed1996

Case report: lymphoepithelial cyst of the pancreas.

The case of a rare lymphoepithelial cyst of the pancreas is presented. The non-specific findings on endoscopic retrograde cholangiopancreaticography, endoscopic ultrasound, computed tomography and magnetic resonance imaging are discussed.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1995

Magnetic resonance angiography of the abdomen.

The applications of abdominal MR angiography have been slow as compared with its applications in the head and neck mainly because of greater technical difficulties in dealing with respiratory motion and the use of the body coil, which has a poorer signal-to-noise ratio than head or surface coils. Further work is needed to reduce motion sensitivity and improve spatial resolution. Flow contrast and depiction of slowly flowing blood could be improved with the use of intravascular contrast agents. 52MR angiography is the imaging method of choice in the evaluation of the portal venous system, systemic veins, and aortic disease. With further technical improvements, it seems likely that applications of MR angiography will also be extended to smaller vessels.

Abdomen↗
PubMed1995

Echo planar imaging of the abdomen.

Echo planar imaging (EPI) is an ultrafast magnetic resonance (MR) imaging method first proposed more than 15 years ago. With EPI, all the information necessary to create an image is obtained very rapidly (typically on the order of 50-150 ms). Special hardware modifications are needed, particularly in the magnetic field gradients and data acquisition systems, to permit such high-speed imaging. In the abdomen, EPI images are insensitive to degradation from breathing or peristaltic motion. The essentially infinite repetition time and lack of motion-induced blurring can improve lesion characterization compared with standard imaging methods. Segmented EPI permits high-resolution T2-weighted images to be acquired within a single breath-hold. Diffusion imaging, which was previously restricted to the brain, can now be done in the abdomen because of the relative insensitivity of EPI images to bulk motion. Diffusion imaging of the kidney has been found to correlate with its functional status. By using EPI readouts, MR angiography can be done more quickly. Further work is needed to improve the spatial resolution and overcome magnetic susceptibility artifacts, particularly with single-shot EPI. Nonetheless, EPI offers considerable potential for improved anatomical and functional imaging of the abdomen.

Abdomen↗