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Biomedical subjects

G Marchal

Publications and source records attributed to G Marchal.

At least 289 records · Page 16Linked to original sources
PubMed1989

Uneven lipomatosis: a pitfall in pancreatic sonography.

A marked difference in echogenicity between the anterior and posterior parts of the pancreatic head was demonstrated by pancreatic ultrasound in 4 patients. This finding could not be related to local pancreatic or peripancreatic pathology. In all patients the dorsal portion of the head, including the uncinate process, appeared less echogenic than the ventral part of the head, body, and tail. The level of demarcation was identical in all 4 cases, coinciding with the expected fusion line of the embryological dorsal and ventral pancreatic origin. Pathology available in 1 patient showed an uneven lipomatosis as an explanation for this hitherto unreported observation.

Aged↗
PubMed1989

Computed tomography of the rectum with water as contrast agent.

The use of intrarectally administered plain tap water as a contrast medium for CT scan of the rectum and sigmoid combined with iv iodine contrast medium was prospectively studied in 28 patients. This method allowed correct demonstration of mural wall abnormalities in all patients and therefore represents a simple, inexpensive, and efficient modality for CT study of the rectum and sigmoid.

Contrast Media↗
PubMed1989

The influence of behavioural states on cerebral blood flow velocity patterns in stable preterm infants.

Previous Doppler ultrasound studies assessing cerebral blood flow velocities in the anterior cerebral artery (ACA) among healthy term and preterm infants, showed a widespread range for the calculated flow indices. However, only one of these studies accounted for the infant's behavioural state. In the present study a stable pattern of the cerebral blood flow velocity tracings and of the Pulsatility Index (PI) was observed during state 1, whereas marked fluctuations in cerebral blood flow velocity and PI were found during state 4 or active wakefulness. During state 2, minor variations of cerebral blood flow velocity and PI occurred though tended to be less pronounced than during active wakefulness. Thus at the time of Doppler assessment the cerebral blood flow velocity pattern and its variability will be better understood by taking into account the behavioural state of the infant.

Behavior↗
PubMed1989

The effect of nimodipine on the evolution of human cerebral infarction studied by PET.

Fourteen patients were studied by positron emission tomography (PET) within 48 h of onset of a hemispheric ischemic stroke and again 7 days later. After the first set of PET scans, the patients were randomized to receive either nimodipine (n = 7) or a carrier solution (n = 7) by intravenous infusion. The infusions were maintained until the end of the second PET studies. CBF, cerebral blood volume (CBV), oxygen extraction ratio (OER), CMRO2, and CMRglc were measured each time. These metabolic and perfusion measurements were performed by standard methods. A surface map of each metabolic and perfusion measurement in the cortical mantle was generated by interpolating between the available slices. The various surface maps representing the physiological characteristics determined in the same or subsequent studies were aligned so that all data sets could be analyzed identically using an array of square regions of interest (ROIs). The functional status of each ROI was recorded at the two intervals following the cerebrovascular accident to characterize the evolution of the infarct, penumbra, and normal brain regions. We presumed the ischemic penumbra to be cortical regions in the proximity of the infarct and perfused at CBF values between 12 and 18 ml/100 g/min on the first PET scan, while densely ischemic regions had CBF of less than 12 nl/100 g/min and normally perfused brain greater than 18 ml/100 g/min. In the densely ischemic zone, CBF increased more in the nimodipine-treated group than in the carrier group. As well, in this region nimodipine reversed the decline in CMRO2 noted in the carrier group, the difference in the changes being significant. In the penumbra zone, comparable trends were noted in OER and CMRO2 but the difference in the changes between the two groups did not reach statistical significance. Changes in CMRglc and CBV were comparable between the two groups in both cortical regions.

Adult↗
PubMed1989

Clinical evaluation of a motion compensated double echo sequence in MRI of the brain.

This study is a clinical evaluation on 5 volunteers and 20 patients of an improved sequence using rephasing gradients for motion compensation, applied to MR imaging of the brain at 1.5 T. The sequence is a double spin echo sequence with a normal first echo at TE = 15 ms and a second echo at TE = 90 ms with first and second order motion compensation in the readout gradient direction; the band width of the second echo is halved for improved S/N. Results demonstrate a dramatic improvement in image quality. Vascular and CSF flow are rephased, ghosting is reduced and signal voids no longer exist. Most remarkable is the substantial suppression of artifacts from voluntary movements such as from swallowing or rotation of the eyes. ECG triggering does not further improve image quality and is thus no longer needed.

Brain↗
PubMed1989

Hypertrophic retromedullary venous drainage in spinal cord tumours: MR visualisation.

Pseudoangiomatous dilatation of retromedullary veins at myelography was noted in three cases of intramedullary spinal cord tumours. This concerned two haemangioblastomas at levels Th8 and L1, respectively, and an ependymoma of the conus terminalis. MRI accurately demonstrated the tumoural mass, together with the enlarged and tortuous draining perimedullary veins. In patients with dilated vascular shadows on myelography, MRI should be performed before medullary angiography to differentiate between spinal vascular malformations and intramedullary tumours with enlarged draining veins.

Adult↗
PubMed1989

Experimental study of the pharmacokinetics and dose response of ferrite particles used as a contrast agent in MRI of the normal liver of the rabbit.

Superparamagnetic ferrite is a specific magnetic resonance imaging (MRI) contrast agent for the liver and the spleen. The large electronic magnetic moments of the ferrite particles create local field inhomogeneities that shorten the transversal relaxation time and reduce the spin-echo amplitude and the intensity of the liver and spleen signals in MR images. MRI was performed at 1.5 T using a SE sequence with TR/TE = 300/15 milliseconds. Pharmacokinetics were studied on five rabbits during five hours and up to 11 days after ferrite injection with doses ranging from 0.2 to 1 mg Fe/kg. Dose responses (0.2 mg to 8 mg Fe/kg) were studied on 11 additional rabbits, at three hours and three days after injection. Results show that the effect of ferrite on the liver images is stable between 30 minutes and 6 hours, and that the liver images recover their intensities before injection after about two days. The liver intensity drops to half its value for a dose of 1.25 mg Fe/kg (for TR/TE = 300/15 milliseconds). Our results support the conclusions from studies on other animal species that ferrite should be considered a useful MRI contrast agent for clinical investigations of the liver.

Animals↗
PubMed1989

Detection of liver metastases with superparamagnetic iron oxide in 15 patients: results of MR imaging at 1.5 T.

The first clinical results of using superparamagnetic ferrite particles as a tissue-specific contrast agent for MR of the liver are reported at high fields (1.5 T). Fifteen patients with proved secondary liver malignancies were studied with plain and contrast-enhanced MR. Superparamagnetic iron oxide was administrated IV in a dose of 20 mumol/kg. Intermediate TR, 820/30, 60 (TR/TE), and long TR, 2200/22, 70, spin-echo sequences were used before and 1 hr after injection of contrast material. Before injection, the largest number of lesions (437) was detected with the T2-weighted sequence. Lesion-to-liver contrast, expressed as the difference between the tumor and liver signal-to-noise, improved after ferrite administration in both sequences from -1 to 20 and from 7 to 15 for the 820/30, 60 sequence and from 9 to 34 and 15 to 21 for the 2200/22, 70 sequence. Despite this significant improvement in terms of the number of lesions detected, contrast-enhanced images did not show significantly more metastases than the unenhanced T2-weighted images did (383, 421, 407, and 407 vs as many as 437, respectively). In this limited study at 1.5 T, the benefit of ferrite enhancement was only marginal when postcontrast images were compared with heavily T2-weighted precontrast scans.

Aged↗
PubMed1989

[Computerized tomography and magnetic resonance imaging of the pelvis in a patient with neurofibromatosis].

A case of intrapelvic neurofibroma is presented in a patient with neurofibromatosis. Magnetic resonance imaging proved to be very sensitive in the demonstration and delineation of the tumoral pelvic mass and the detection of smaller subcutaneous lesions. Direct coronal and sagittal images provided important information to the surgeon to evaluate the cranial and caudal extension and the anatomic boundaries of the lesion.

Adult↗
PubMed1989

A case of intracranial chordoma investigated by MRI and CT studies.

MR imaging of an intracranial chordoma is described. The tumor appeared strongly hyperintense on T2 weighted images and moderately hypointense on T1 weighted images with a strong homogeneous contrast enhancement after IV administration of Gadolinium Dota. MR is superior to CT in delineating the tumor margins and in defining its relationship to the brainstem, optic chiasm and the vasculature, providing essential pre-operative information.

Aged↗