Ultrasound: present and future.
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Contrast Media↗
Biomedical subjects
L Pourcelot
Publications and source records attributed to L Pourcelot.
[Color Doppler ultrasonography of local recurrent breast cancer].
Local lesions occurring after conservative surgery for breast neoplasms require diagnostic means capable of detecting and assessing the recurrence of such cancers. In the present color-coded Doppler was used in 20 women who had under gone conservative surgery (mean 4 years before) to screen all suspect lesions. Among the 14 malignant lesions assessed histologically, one or more arterial vessels were detected inside or beside the lesion in 13. Among the 6 benign lesions, only of one arterial vessel was detected, in all cases far from the lesion (12.5 to 3.3 mm). No significant difference was observed for systolic velocities and resistance index. These results indicate high accuracy of color coded Doppler examination associated with echotomography and mammography for positive diagnosis of recurrent lesions in post-conservative follow-up of breast cancer.
Adult↗
[In utero measurement of the umbilical cord in full term pregnancy].
OBJECTIVE: The length of the umbilical cord varies widely from one pregnancy to another. Although its average length is 50 cm, this measurement could vary from as little as 20 cm to more than one metre. The purpose of our study was to evaluate, in utero, the length of the umbilical cord during the third trimester of pregnancy knowing the propagation velocity of the pressure wave along the cord. MATERIAL AND METHODS: The computation of the apparent length requires two ultrasound transducers, one situated at the aortic fetal arch, the other at the placental extremity of the umbilical artery. Knowing the velocity of the pressure wave (v), as well as the time interval between the systolic peak of two waves (delta t), we can deduce the length of the umbilical cord (delta t x v). RESULTS: The comparison between the calculated length and the actual length measured shows a significant correlation with a probability of 1%. CONCLUSION: The knowledge of the length of the umbilical cord is quite useful in the physio-pathological interpretation of the placental resistance index. It is also of interest, before the delivery, to know the length of the cord in order to foresee dystocy and how it relates cord which is either too short or too long.
Blood Flow Velocity↗
[Nuclear magnetic resonance spectroscopy: methodology and applications to the study of asphyxia neonatorum].
Cerebral metabolism has been extensively studied by magnetic resonance spectroscopy (MRS). MRS allows the study of neonates brain maturation as well as the onset and the evolution of brain injury. The use of phosphorous spectroscopy allows the quantification of phosphorylated metabolites. Thus, the measurement of the relative concentrations of creatine-phosphate and inorganic-phosphate is a prognostic factor of the outcome of a neonate after birth asphyxia. Absolute concentrations have more recently been studied and seem to be more significant. Proton MRS gives access to brain metabolites such as choline, lactate, N-acetyl aspartate and taurine. Its use is more recent than the phosphorous spectroscopy but first results already show its potential in neonatology.
Asphyxia Neonatorum↗
[Cognitive evoked potentials in children: normal and abnormal development].
The first part of this review on event-related potentials (ERPs) in children summarizes the role of ERPs in the study of normal cognitive development. The ERPs vary both as a function of the age of the child and also as a function of the cognitive processes that are required by the tasks. Topographical studies allow one to identify cortical regions involved in specific cognitive processes, and monitor their age-related changes. The second part of this paper reviews two examples of abnormal cognitive development (attention deficit hyperactivity disorder and childhood autism) where the ERPs allow a better understanding of the dysfunction underlying the observed cognitive disorders.
Adolescent↗
Concurrent changes in intracranial pressure, cerebral blood flow velocity, and brain energy metabolism in rabbits with acute intracranial hypertension.
The relationship between intracranial pressure or cerebral perfusion pressure (CPP), cerebral blood flow, and brain energy failure is unpredictable throughout the development of acute intracranial hypertension. The purpose of the present study was to correlate intracranial pressure with cerebral blood flow velocities and brain energy metabolism in adult rabbits. The acute intracranial hypertension was achieved by pressure transmission. Transcranial Doppler wave-forms were obtained from the basilar artery for monitoring cerebral blood flow velocities. 31P-Magnetic resonance spectroscopy was used to assess brain energy metabolism. The diastolic blood flow velocity began to decrease significantly (34.5%) when the intracranial pressure was equal to half the diastolic arterial pressure for a CPP of 36 +/- 18 mmHg. Circulatory cerebral resistances increased significantly (55%) for the same value of CPP. Diastolic frequency was near zero when intracranial pressure approached diastolic arterial pressure (51 +/- 12 mmHg), corresponding to a CPP of 30 +/- 15 mmHg. At the same time, only a tendency for brain energy metabolism to decrease was observed. Consequently, transcranial Doppler sonography could be proposed for the follow-up of intracranial hypertension. Magnetic resonance spectroscopy could help to monitor these patients and could be especially proposed in case of high intracranial pressure (near diastolic arterial pressure). The joint use of these two methods would help in making appropriate therapeutic decision in humans.
Animals↗
Real-time processing of ultrasonic Doppler signals of fetal activity.
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Algorithms↗
Ultrasound imaging of psoriatic skin: a noninvasive technique to evaluate treatment of psoriasis.
BACKGROUND: The aim of our study was to image psoriasis plaques by ultrasound to assess the changes in psoriasis and to measure and quantify them objectively. MATERIALS AND METHODS: Thirty-one psoriasis plaques were studied in 19 patients. Measurements of skin thickness were obtained with a high resolution B-mode echographic system. RESULTS: Some changes were seen in psoriatic skin. A new structural element was observed: a wide subepidermal nonechogenic band. The other changes were a decrease in dermal echoes that were less intense and less dense, and an increase in the epidermal and dermal skin thicknesses. The skin thickness was increased in all psoriasis plaques as compared to apparently normal skin (P < 0.001). The average increase was 67% for whole skin and 200% for epidermis. CONCLUSIONS: Ultrasound imaging of psoriatic skin allowed the identification of different skin changes induced by psoriasis, and particularly, the differentiation between epidermal and dermal alterations. We presume that epidermal thickness reflects epidermal proliferation and desquamation, and the increase in the dermal and whole skin thickness reflects infiltration. We feel that ultrasound imaging of psoriatic skin is a quantitative method that is as easy and noninvasive as the psoriasis area and severity index (PASI). It could be used for following up patients with psoriasis and could achieve widespread use, especially in research protocols.
Adult↗
Cerebral vasodilation capacity: acute intracranial hypertension and supra- and infra-tentorial artery velocity recording.
This experiment is the first to compare cerebral vasomotor reactivity in the supra- and infra-tentorial regions in baseline conditions and during progressive acute intracranial hypertension. The increase in intracranial pressure was performed using liquid pressure transmission in two groups of 16 rabbits by elevating a saline infusion bottle connected to the subdural space. Cerebral microvessel dilation capacity was studied using acetazolamide arterial infusion during three stages of 20 min: at baseline conditions, with an intracranial pressure value equal to half the diastolic arterial pressure and with an intracranial pressure equal to the diastolic arterial pressure. The effects of acetazolamide in the basilar artery and in the carotid siphon were simultaneously monitored by transcranial Doppler sonography during all the experiments. The changes in cerebral vasomotor reactivity occurred with the same intensity and latency in both vascular compartments in baseline conditions. The maximum amplitude of changes happened 30 s later in the basilar artery than in the carotid siphon. When intracranial pressure was above half the diastolic arterial pressure, the vasomotor tone began to decrease in the carotid siphon which supplies a small region of the rabbit brain, whereas it was maintained in the basilar artery. This effect could be explained by brain tissue hypertension. Vasomotor reactivity had nearly disappeared in all the cerebral arteries investigated when intracranial hypertension was equal to the diastolic arterial pressure. These results show evidence of a direct and late effect of acute elevation of intracranial pressure on cerebral microvascular tone. This begins in the supra-tentorial region but there is an early local effect on the carotid siphon due to the brain tissue pressure.
Animals↗
99Tcm-HMPAO cerebral scintigraphy and transcranial pulsed Doppler in acute intracranial hypertension in rabbits.
The purpose of this study was to compare transcranial Doppler sonography (TCD) and 99Tcm-HMPAO cerebral scintigraphy in detecting the effects of acute intracranial hypertension by pressure transmission using a previously validated model. In 20 New Zealand rabbits, cerebral blood flow velocities of basilar artery and carotid siphon were simultaneously monitored in baseline conditions and during acute intracranial hypertension by pressure transmission. This hypertension was induced by progressive steps of 5 mmHg, for a 5 min duration by elevating a saline infusion bottle connected to the subdural space. In baseline conditions, significant correlations were found between basilar artery resistive index and 99Tcm-HMPAO uptake in brain stem, r = 0.5 (p < 0.05) and posterior cerebral areas, r = 0.78 (p < 0.001). Severe intracranial hypertension equal to the diastolic arterial pressure with a cerebral perfusion pressure of 22.8 +/- 12.7 mmHg significantly decreased the basilar artery blood flow velocities and global 99Tcm-HMPAO cerebral uptake. At this level of intracranial pressure, few correlations between the two methods were observed. TCD detected relatively high blood-flow velocities in the carotid siphon appearing to result from proximal cerebral artery vasospasm. Transcranial pulsed Doppler provides data about haemodynamic changes such as hypoperfusion, vascular resistance increase in the basilar artery territory and vasospasm of the carotid siphon. 99Tcm-HMPAO scintigraphy, which has not yet been studied during intracranial hypertension, gave immediate information on local cerebral perfusion. Cerebral scintigraphy demonstrated a significant diffuse and heterogeneous decrease in cerebral blood flow, without dissociation between supratentorial and infratentorial territories, and tissue perfusion deficit owing to arterial vasospasm. TCD provides emergency investigation in patients with severe head injuries or hydrocephalus. 99Tcm-HMPAO complements TCD in cases of vasospasm and in determining an area of perfusion tissue deficit.
Animals↗
Experimental and numerical models of acute intracranial hypertension and basilar artery blood flow velocity.
A numerical model based on Navier-Stokes equations was used in conjunction with an experimental model in rabbits to study the effects of acute intracranial hypertension on basilar artery blood flow velocity. The hypertension was induced by pressure transmission via an epidural pressure sensor inserted into a parietal intracranial opening. A critical value of half of the diastolic arterial pressure for the intracranial cerebral pressure was determined by both numerical and experimental models. At this intracranial cerebral pressure level, the total input resistance and total input compliance, determined by the numerical model, exhibited an increase of 27% and 10%, respectively, and the tissular compliance a decrease of 25% from their physiologic baseline values. When the intracranial cerebral pressure reaches the level of the diastolic arterial pressure, a zero diastolic flow is observed into the cerebral vascular system. This study validates the theoretical model, which could be used in assessing intracranial cerebral pressure noninvasively in humans when O2 pressure can be stabilized.
Acute Disease↗
Sonographic lung surface evaluation in pulmonary sarcoidosis: preliminary results.
The value of sonography in lung diseases such as sarcoidosis is not established. Twelve patients with pulmonary sarcoidosis and eight control subjects underwent a sonographic examination using a high frequency probe (7.5 MHz). The normal lung surface showed smooth and regular hyperechoic patterns, respiratory motions, and occasionally minute interruptions with comet tails. All patients with sarcoidosis showed various surface abnormalities, which appeared irregular and rough with coarse interruptions, producing an increase of artifacts. Nodular patterns were found in nine of 12 patients (75%). Sonography also revealed abnormalities not diagnosed by chest radiographs (n = 2). These findings could offer an complementary approach for evaluating sarcoidosis.
Adult↗
Ultrasonic signs of pneumothorax: preliminary work.
Ultrasonography is considered to have limited application in respiratory diseases because air reflects sound waves. Twenty-four patients with radiologically confirmed pneumothorax and 100 healthy subjects underwent sonography. In all normal subjects, the hyperechoic pulmonary interface showed respiratory motions termed the "gliding sign" with some comet-tail artifacts. Sonographic signs were shown in all pneumothoraces: disappearance of the gliding sign and no comet tails. The extent of collapse cannot be evaluated, but it is possible to determine its area in partial pneumothorax (N = 5). The follow-up (N = 8) showed the reappearance of the gliding sign. Ultrasonography may be helpful in diagnosing pneumothorax in certain cases.
Adolescent↗
The use of perioperative Doppler ultrasound as a screening test for acute tubular necrosis.
For many years Doppler ultrasound has helped to identify the cause of renal allograft dysfunction. However, Doppler examinations were often performed after the onset of acute renal failure. In the present study we used Doppler ultrasound during grafting to follow changes in renovascular resistance. As early as 30 min after the renal artery had been unclamped, the calculated resistance index (RI) at the hilar part of the renal artery was significantly higher in the group of patients who developed acute tubular necrosis (ATN) than in the group of patients with early normalization of renal function (P = 0.05). This result did not correlate with raised cold and warm ischemia times and serum creatinine level on discharge in patients who presented with ATN. RI higher than 0.730 min after unclamping allows for an identification of those grafts at greater risk for the development of ATN and should be an indication for the early introduction of intensive therapy.
Adult↗
Detection of fetal breathing and cardiac movements and rhythms in ultrasonic Doppler signal recorded on the surface of the maternal abdomen.
It is proposed to use information on the direction of reflector movement and extensive filtering in the detection of fetal breathing and cardiac movements in the ultrasonic Doppler signal recorded on the surface of the material abdomen. The method appears fairly insensitive to spurious signals and allows those of interest to be distinguished without any reference technique. A decision rule for breathing and cardiac rhythm detection, incorporating movement direction, amplitude, shape and periodicity criteria, is also proposed.
Female↗
Ultrasonically guided aspiration biopsy in osteolytic bone lesions of the chest wall.
Sixteen consecutive patients with one or more osteolytic bone lesions of the chest wall radiologically confirmed underwent ultrasonically guided aspiration biopsy. Nine patients (56.2 percent) had bronchogenic carcinoma with a direct extension. Other diagnostic techniques had failed to diagnose disease in these patients. The lesion showed heterogeneous echogenicity (n = 16) caused by the hyperechoic signals of bone fragments. The interruption of the cortex bone was detected in all cases and extraosseous tumor portion in 14 of 16 patients (87.5 percent). No respiratory motions of the lesion could be demonstrated (n = 16). Definitive histologic diagnosis was made in 14 of the 16 patients (87.5 percent). In malignancy, diagnosis was established in 13 of 14 patients (92.8 percent). Of two confirmed benign lesions, one diagnosis of tuberculosis was obtained. No complication occurred. Sonography and consequently ultrasonically guided aspiration biopsy are a useful, accurate, safe, and low-cost technique for osteolytic lesions in thoracic diseases.
Adult↗
Peripheral pulmonary lesions: ultrasonic features and ultrasonically guided fine needle aspiration biopsy.
When transthoracic biopsy is required for diagnosing lung diseases, radiographic procedures are the methods of choice, sonographic application being still limited. Sixty-four consecutive patients with pulmonary lesions adjacent to the chest wall underwent sonography. Findings showed hypoechoic homogeneous lesions (56 cases) with posterior regular margin (57 cases). Increasing echoes deep to the mass and sonographic interruption of hyperechoic surface were seen in all patients. In two cases, chest wall invasion had been diagnosed. Histologic diagnosis was made in 55 of the 64 patients (85.9%). Two pneumothoraces occurred. Sonography is a useful, accurate, and safe technique for diagnosing selected pulmonary lesions.
Adult↗
[Modeling of feto-placental circulation. Clinical applications apropos of 21 patients having no or inverse diastolic umbilical flow].
The placental resistance index: (S-D)/S (S: represents the amplitude of the systolic peak and D: the amplitude of the telediastolic peak) is constantly inferior to one from the 14th-16th week of amenorrhea during a normal pregnancy. The diastolic umbilical arterial blood flow is continuous because of low placental vascular resistance. From a clinical study of 21 patients with an absent or reversed end diastolic flow in umbilical artery waveforms, an obliterative process in the placental vascular tree was observed. A computer model was used to stimulate the reversed end diastolic flow in umbilical artery waveforms when the placental resistance increased. This haemodynamic approach shows that the placental blood flow decreased, and that the arterial blood pressure, as well as the pulse wave velocity increased when the placental resistance increased. The increase in the difference between the umbilical resistance and the placental resistance caused a reduction of the diastolic flow owing to a progressive increase of the pulse wave velocity reflected. It was concluded that there is a relation between perturbations in placental vascular bed and the flow in umbilical artery waveforms.
Adult↗