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Biomedical subjects

R Meuli

Publications and source records attributed to R Meuli.

At least 55 records · Page 3Linked to original sources
PubMed1996

[Magnetic resonance angiography in vertebro-basilar ischemic accidents].

This study evaluates the use of MR angiography in the diagnosis of vertebrobasilar stroke. The MRI/MR angiography and clinical presentation of 50 unselected adult patients who presented with ischemic symptoms in the vertebrobasilar territory (10 TIAs, 40 strokes) were prospectively evaluated. Conventional T1 and T2-spin echo sequences were obtained for evaluation of the brain parenchyma, with gadolinium injection in 41 cases and 3D time-of-flight MR angiography in all patients. Data were reconstructed with a maximal intensity projection algorithm and displayed in 3D. Arterial and parenchymal lesions and clinical data were correlated. MR angiography showed intracranial vertebrobasilar lesions in 30 patients (5 stenosis or occlusion of a vertebral artery, 17 stenosis or occlusion of the basilar artery, 6 stenosis of arterial branches of the basilar artery, 10 dolichoectasia of the basilar artery). 7 patients had multiple lesions. Recognized etiologies of the strokes were: 23 vertebrobasilar lesions, 16 nonvertebrobasilar causes, 6 mixed (vertebrobasilar and associated alternative causes) cases, while 5 cases had no recognized cause of stroke. Our study demonstrates a high incidence of intracranial arterial lesions in patients suffering from vertebrobasilar stroke and suggests that MRA can help in a noninvasive way to determine the origin of vertebrobasilar strokes.

Adult↗
PubMed1996

Cushing's disease due to a giant pituitary adenoma in early infancy: CT and MRI features.

We report the case of a 12-month-old girl presenting with diabetes insipidus and Cushing s disease. Brain magnetic resonance imaging (MRI) demonstrated a large tumour arising from the sella turcica, extending up to the foramen of Monro and invading the cavernous sinuses. Surgery was performed to remove the suprasellar part of the tumour, and histology revealed an adrenocorticotrophin (ACTH) secreting pituitary adenoma. This entity is very rare in this age group and the MRI features have not previously been described.

Adenoma↗
PubMed1996

Helical CT angiography for traumatic aortic rupture: correlation with aortography and surgery in five cases.

Dynamic computed tomography (CT) is frequently performed to assess the mediastinum in trauma patients with a suspected thoracic aortic rupture. Its usefulness lies in demonstrating a mediastinal hematoma. However, many patients still undergo conventional aortography despite a normal chest. CT, because of a perceived insensitivity of this technique for diagnosing aortic rupture. One application of helical CT is CT angiography, in which multiple thin sections are acquired through a blood vessel during the injection of iodinated contrast. Good demonstration of vascular pathology can be achieved, especially with 3-D reconstructions. This article reviews a series of four surgically proven thoracic aortic ruptures studied using helical CT, and one case proven to be false-positive by both helical CT angiography and conventional angiography. Correlation between conventional and helical CT angiography was excellent, with similar findings and the same interpretation pitfalls. Helical CT is fast and noninvasive. Combined examination of other anatomical areas can be performed in the same procedure in major trauma patients. Helical CT may potentially decrease the need for aortography in these acutely injured patients.

Adult↗
PubMed1995

[Correlation between arthroscopy and MRI in the diagnosis of meniscal tears of the knee].

The sensibility and specificity of MRI diagnosis of meniscal tears are still debated. We compared the radiologic and arthroscopic diagnosis of 37 patients who underwent MRI study of the knee, followed by arthroscopic surgery. Meniscal lesions were classified according to their size and the grading system of Lotysch and Crues (1). In patients without previous arthroscopic surgery (n = 32), 92% of the grade-3b lesions are found to be torn at surgery. The probability for tears is weaker for grade-3a lesions (one meniscus torn out of three). An intact or slightly degenerated meniscus on MRI (grades 1 and 2) relates in 91% of cases to a normal fibrocartilage at arthroscopy. In patients with previous knee surgery (n = 5), the specificity of MRI for grade-3b lesions is weak (55%), owing to the presence of granulation tissue. Our results agree with those of recent publications, confirming the high value of MRI in the diagnosis of traumatic or degenerative meniscal tears. The use of a grading system incorporating the size of the lesion gives a better specificity to MRI diagnosis.

Adult↗
PubMed1995

Traumatic chest lesions in patients with severe head trauma: a comparative study with computed tomography and conventional chest roentgenograms.

In patients with severe craniocerebral trauma, who need a continuous positive-pressure breathing, the detection of pulmonary and mediastinal traumatic lesions, especially pneumothorax, may alter the management. The aim of this study is to evaluate the efficiency and accuracy of conventional supine chest roentgenograms to detect the associated traumatic chest lesions in severe craniocerebral trauma and to compare their value as a diagnostic method for the identification of unsuspected lesions with a limited chest computed tomographic (CT) examination. Forty-seven consecutive patients with severe craniocerebral trauma underwent head CT and a prospective limited CT examination of the thorax in the same session. Nine patients (19.1%) presented a pneumothorax, bilateral in one case. Six pneumothoraces (60%) were identified both on conventional chest roentgenograms and CT, whereas in four cases (40%), the lesion was only detectable on CT. The CT study also showed 31 areas of pulmonary parenchymal contusions in 19 subjects (40%), whereas the conventional chest roentgenograms demonstrated 17 areas of contusions in 11 (23%) subjects. One thoracic aorta and one right diaphragm rupture were detected on CT study. On the conventional chest roentgenograms the mediastinal vascular injury was overlooked, whereas the right diaphragmatic rupture was highly suspected. The limited chest CT examination supplied additional information in 30% of patients. In 12.7% of patients, this information was clinically significant enough to alter the management. In patients with severe craniocerebral trauma evaluation of associated chest trauma by a supplementary limited chest CT, examination provides more and precise information about the size and severity of mediastinal and pulmonary lesions with a superior detectability of pneumothorax.

Adolescent↗
PubMed1995

Genetic difference in HLA-DR phenotypes between coeliac disease and transitory gluten intolerance.

Genetic differences in HLA phenotypes were studied in coeliac disease to investigate why some patients do not react with mucosal damage after gluten challenge. Forty five children with coeliac disease and 16 with transitory gluten intolerance were typed; 76 subjects served as controls. HLA phenotypes in children with coeliac disease had significantly higher proportions of DR3/X and DR5/7 than controls (48.8% v 11.8% and 26.7% v 5.3%). Children with transitory gluten intolerance had lower DR3/X (43.8%) than children with coeliac disease and there were no DR5/7 phenotypes. Further analysis of similarly well defined cases might show whether genetic differences in the DR3/X and DR5/7 phenotypes can serve as a marker for the permanence of gluten intolerance.

Adolescent↗
PubMed1994

Compensatory renal growth in children and adults studied by Doppler sonography.

To identify modifications of kidney morphology and of the time-velocity spectral waveform associated with long-term compensatory hypertrophy, spectral Doppler sonography was performed in 30 children and adults with solitary kidneys 7 years to 28 years following nephrectomy. Doppler signals were obtained from three arterial sites in each kidney. The average renal volume was 207 mL and the mean hypertrophy of the kidneys was 186%. The mean value of pulsatility (PI) and Pourcelot (RI) indexes of solitary hypertrophied kidneys was significantly lower than that of normal paired kidneys or allografts with normal function described in the literature. The PI and RI were found to correlate inversely with the kidney volume and the body surface area (BSA). In spite of a long follow-up time, no patient suffered from renal failure. This study suggests that in the case of solitary kidney, specific ranges of PI and RI should be employed rather than those used with paired kidneys.

Adolescent↗
PubMed1994

Methods for reconstructing phase sensitive slice profiles in magnetic resonance imaging.

The experimental determination of slice profiles excited by applying radiofrequency pulses in the presence of a gradient generally results in magnitude profiles. The conditions necessary to obtain a phase-sensitive picture of the profile of a slice are discussed. A distinction is made between the "excitation profile" (distribution of the transverse magnetization immediately after the RF pulse) and the "slice profile" (distribution after refocusing by gradient reversal and/or imperfect gradient switching). Methods are presented that allow one to obtain either the excitation profile or the slice profile. It is shown that phase encoding along the direction of the slice selection gradient provides a convenient protocol for obtaining the distribution of both the real and imaginary parts of the slice profile. The phase sensitive excitation profile can be obtained by frequency encoding. These methods were used to evaluate the performance of various shaped pulses.

Algorithms↗
PubMed1994

Pure midbrain infarction: clinical syndromes, MRI, and etiologic patterns.

We studied 22 patients with first stroke and infarct limited to the midbrain on MRI. We selected these patients (8%) from 281 with posterior circulation infarct admitted consecutively into a primary care center. All patients underwent a systematic protocol of investigations including MR imaging and angiography, and echocardiography. Most infarcts fitted well to arterial territories drawn in preestablished templates. Middle midbrain involvement was the most common, mainly in the paramedian territory supplied by the basilar artery. Infarct in the mesencephalic territory of the posterior cerebral artery was less common, while superior cerebellar artery territory infarct was extremely rare, and posterior choroidal artery territory infarct did not occur. The neurologic picture was dominated by eye-movement disorders. Patients with isolated upper or lower midbrain infarct had no localizing clinical findings, but patients with middle midbrain infarct had a localizing picture mainly with nuclear or fascicular third nerve palsies that commonly developed in isolation. Vertical gaze paresis, pure motor hemiparesis, four-limb ataxia from unilateral lesion, and hypesthetic ataxic hemiparesis also occurred. Contrary to a common view, cardioembolism was not a more common etiology than basilar artery stenosis or small-vessel disease.

Aged↗
PubMed1993

[Role of radiology in the diagnosis of aortic dissection].

Aortic dissection requires a prompt diagnosis and must be treated without delay in order to reduce the mortality rate. Whereas aortic dissection involving the ascending aorta (type A) requires immediate surgery, aortic dissection involving the descending aorta (type B) will usually be treated conservatively. This review article reevaluates the respective efficiency of conventional and modern radiological means offered in a well equipped university hospital.

Aortic Dissection↗
PubMed1993

The etiology of posterior circulation infarcts: a prospective study using magnetic resonance imaging and magnetic resonance angiography.

In a prospective study of 70 patients with infarcts in the posterior circulation admitted consecutively to a population-based primary-care center, we assessed infarct location and etiology using magnetic resonance imaging, three-dimensional time-of-flight magnetic resonance angiography, and noninvasive cardiac tests. The brainstem (mainly the paramedian pons) was the most commonly infarcted site (41/70, 59%), followed by the cerebellum (33/70, 47%). Combined supra- and infratentorial multiple vertebrobasilar infarcts occurred in 11 patients (16%). Overall, 27 patients (39%) had > or = 50% stenosis or occlusion of the basilar artery. There were other large-artery lesions in 19 patients (27%), including vertebral (V2-V4) stenosis or occlusion (in seven) and dolichoectatic vertebral/basilar arteries (in 12). Fifteen of the 70 patients had a potential cardiac source of embolism, which coexisted with large-artery disease in more than one-third of the cases. Cerebellar infarct without concomitant brainstem or occipital infarct was associated with cardioembolism (67%), while isolated paramedian pontine or midbrain infarct was associated with basilar artery stenosis (71%), suggesting in situ occlusion of the mouth of the perforators off the stenosed basilar artery. After exclusion of other potential causes of stroke, presumed small-artery disease associated with chronic hypertension remained the likely etiology in only 11 patients (16%), but these infarcts were not associated with any of the classical lacunar syndromes. Our findings emphasize the high frequency of severe intracranial large-artery disease in posterior circulation infarcts.

Aged↗
PubMed1989

[Conservative treatment of splenic injuries in the adult].

Because of the risk of overwhelming post-splenectomy infection, the current trend favors conservative treatment for splenic trauma. Out of a total of 70 cases of splenic trauma in adults seen over the last 5 1/2 years, 19 spleens were preserved, 13 with, 6 without operations. Ten operated spleens were examined by Duplex-sonography, on average 38 months after surgery. The results show that in all cases, the spleen was morphologically and hemodynamically restored to normal.

Adult↗
PubMed1985

[Quantitative measurement of blood flow with an 128-channel Doppler device. Present status of research and future outlook].

The recent development of a new multigate pulsed Doppler system used in conjunction with an A-mode scan allows real time display of the velocity profiles across the vessel and quantitative flow measurement. Experimental in-vitro and in-vivo studies showed an excellent correlation between flow measurements obtained by this noninvasive method and by direct timed collection. Preliminary results of the post-occlusive hyperaemic response in normals and in patients with iliac stenosis are presented. Although no statistical comparison is allowed, it appears that the hyperaemic response is diminished when an iliac stenosis is present. A non-invasive method of quantifying the haemodynamic significance of profunda femoris artery stenosis is described. Finally, the velocity profiles and the flow curves in PTFE grafts were studied and compared to the flow patterns of the normal superficial femoral artery. The differences observed between the two conditions might explain the low patency rate of the synthetic grafts. Other fields of application of the method are suggested. The future development of a Duplex scanner combining B-mode imaging and the multigate Doppler system will allow the exploration of vessels within the abdomen and thorax: portal vein, in situ or transplanted renal arteries, ascending and abdominal aorta.

Adult↗
PubMedDate not supplied

Using 80 kVp versus 120 kVp in perfusion CT measurement of regional cerebral blood flow.

Perfusion CT studies of regional cerebral blood flow (rCBF), involving sequential acquisition of cerebral CT sections during IV contrast material administration, have classically been reported to be achieved at 120 kVp. We hypothesized that using 80 kVp should result in the same image quality while significantly lowering the patient's radiation dose, and we evaluated this assumption. In five patients undergoing cerebral CT survey, one section level was imaged at 120 kVp and 80 kVp, before and after IV administration of iodinated contrast material. These four cerebral CT sections obtained in each patient were analyzed with special interest to contrast, noise, and radiation dose. Contrast enhancement at 80 kVp is significantly increased (P < .001), as well as contrast between gray matter and white matter after contrast enhancement (P < .001). Mean noise at 80 kVp is not statistically different (P = .042). Finally, performance of perfusion CT studies at 80 kVp, keeping mAs constant, lowers the radiation dose by a factor of 2.8. We, thus, conclude that 80 kVp acquisition of perfusion CT studies of rCBF will result in increased contrast enhancement and should improve rCBF analysis, with a reduced patient's irradiation.

Brain↗