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Biomedical subjects

J P Tasu

Publications and source records attributed to J P Tasu.

At least 19 recordsLinked to original sources
PubMed2006

Legionnaire's pneumonia: is there really an interstitial disease?

OBJECTIVE: Legionella pneumonia is usually classified as "atypical pneumonia", which suggests a predominance of interstitial patterns in chest X-rays. Based on a selection of recent clinical cases and a brief review of the literature, the aim of the study is to clarify, how far the actual radiological findings would be consistent with these expectations. PATIENTS AND METHODS: A retrospective analysis of 18 epidemic personal cases and a review of the literature data were performed to describe the chest X-ray findings of Legionella pneumophila (LP) community acquired pneumonia. X-ray review was performed simultaneously and in consensus by two radiologists (J.P.T., E.C.) and a physician (C.G.). RESULTS: From our series, 17 patients had an abnormal chest X-ray on admission. Among these pathological X-ray cases, infiltrates were more often confluent (n=16), or patchy (n=7), rather than interstitial (n=1). Fifteen patients had infiltrates involving the lower lung fields. Bilateral distribution of abnormalities and pleural effusion were each observed in three cases. Radiological findings deteriorated between the second and seventh days following admission, particularly in the form of patchy infiltrates with pleural effusion. The review of the literature is consistent with these findings, by reporting prevalent confluent or patchy infiltrates. CONCLUSIONS: These findings are consistent with the physiopathological particularity of this affection and incite us to avoid the classification "atypical pneumonia" in radiologic terminology. This term is more appropriate for clinical and microbiological use.

Female↗
PubMed2005

[A new method for radio-carpal joint injection].

OBJECTIVE: Previous techniques for radiocarpal joint injection introduce the needle directly between the navicular and the radius. We propose here a new technique using the same puncture site for midcarpal and radiocarpal arthrograms without need for needle reinsertion. MATERIALS AND METHODS: A prospective study of 85 radiocarpal injections for arthrography was performed. For each case, the needle tip was positioned at the medial part of the proximal scaphoid, under the mid carpal joint, and directed obliquely with a 45 degrees angle to the joint space to reach the radiocarpal joint. In case of midcarpal and radiocarpal arthrograms, a single puncture site was always used. RESULTS: Injection of the radiocarpal joint was successful in 82 of the 82 cases. CONCLUSION: The method proposed here is simple, efficient and uses a single site of puncture in cases requiring bi-compartmental injections.

Arthrography↗
PubMed2001

[Evaluation of plain abdominal radiography prescriptions in a university hospital center].

OBJECTIVES: The aim of this study was to evaluate the prescription, impact and diagnostic utility of plain abdominal radiography in a University Hospital. METHODS: Plain abdominal radiography series performed over 15 consecutive days were evaluated for quality and agreement with the patient's clinical status. Agreement between the final diagnosis and the radiographic findings were also compared. Contribution of plain abdominal radiography to final diagnosis was assessed on the basis of the conclusions on the hospital discharge report or from those drawn from a telephone survey. The same relationship was also assessed in terms of clinician status (medical student, resident physician, senior physician). RESULTS: The series included 175 radiography series (11.6 per day). In 86% of the cases, the choice of views was adapted to the clinical context. In 14% it was not. The quality of the x-rays was found to be unsatisfactory in 17%, good in 63% and excellent in 20%. The radiography was considered to be contributive to the final diagnosis in 13% of the cases and non-contributive in 87%. Clinician status was not correlated with the degree of usefulness for final diagnosis. Finally, the prescription was in agreement with standard guidelines in 28% of the cases and not in agreement in 72%. CONCLUSION: Plain abdominal radiographs are neither sensitive nor specific, frequently misleading, and costly per specific and correct diagnosis. Better physician awareness is required to limit the number of unnecessary examinations.

Abdomen↗
PubMed2001

Precision of magnetic resonance velocity and acceleration measurements: theoretical issues and phantom experiments.

Magnetic resonance (MR) sequences have been developed for acquiring multiple components of velocity and/or acceleration in a reasonable time and with a single acquisition. They have many parameters that influence the precision of measurements: NS, the number of flow-encoding steps; NEX, the number of signal accumulations; and ND, the number of dimensions. Our aims were to establish a general relationship revealing the precision of these measurements as a function of NS, ND, and NEX and to validate it by experiments using phantoms. Previous work on precision has been restricted to two-step (NS = 2) or 1D (ND = 1) MR velocity measurements. We describe a comprehensive approach that encompasses both multistep and multidimensional strategies. Our theoretical formula gives the precision of velocity and acceleration measurements. It was validated experimentally with measurements on a rotating disk phantom. This phantom was much easier to handle than fluid-based phantoms. It could be used to assess both velocity and acceleration sequences and provided accurate and precise assessments over a wide, adjustable range of values within a single experiment. Increasing each of the three parameters, NS, ND, and NEX, improves the precision but makes the acquisition time longer. However, if only one parameter is to be assessed, maximizing the number of steps (NS) is the most efficient way of improving the precision of measurements; if several parameters are of interest, they should be measured simultaneously. By contrast, increasing the number of signals accumulated (NEX) is the least efficient strategy.

Acceleration↗
PubMed2000

Estimation of pressure gradients in pulsatile flow from magnetic resonance acceleration measurements.

A method for estimating pressure gradients from MR images is demonstrated. Making the usual assumption that the flowing medium is a Newtonian fluid, and with appropriate boundary conditions, the inertial forces (or acceleration components of the flow) are proportional to the pressure gradients. The technique shown here is based on an evaluation of the inertial forces from Fourier acceleration encoding. This method provides a direct measurement of the total acceleration defined as the sum of the velocity derivative vs. time and the convective acceleration. The technique was experimentally validated by comparing MR and manometer pressure gradient measurements obtained in a pulsatile flow phantom. The results indicate that the MR determination of pressure gradients from an acceleration measurement is feasible with a good correlation with the true measurements (r = 0.97). The feasibility of the method is demonstrated in the aorta of a normal volunteer. Magn Reson Med 44:66-72, 2000.

Adult↗
PubMed2000

Multidimensional MR mapping of multiple components of velocity and acceleration by fourier phase encoding with a small number of encoding steps.

Previous studies have shown that the multi-step approach of velocity or acceleration encoding is highly efficient in terms of the signal-to-noise ratio per unit time. This work describes a multidimensional extension of this method for simultaneously measuring multiple components of velocity and acceleration with a few encoding steps. N flow dimensions were encoded with an ND-matrix, obtained by combining the various flow-encoding gradients. The small matrix obtained with as few as two encoding steps can be extended by zero-filling in all N dimensions and using ND-Fourier transformation to obtain the maximum of the resulting peak in the ND-matrix, which gives simultaneously all the components of velocity and/or acceleration. The processing time was shortened by using a method of phase computation that gives the same precision as Fourier transformation, but is much faster. A rotating disk was used to show that the velocity-to-noise ratio increases with the number of dimensions acquired, demonstrating the efficiency of multidimensional flow measurements. The feasibility of the method is illustrated by 3D maps of the myocardium velocity, and 2D measurement of velocity and acceleration in the ascending aorta-both obtained by multidimensional phase encoding in volunteers.

Acceleration↗
PubMed2000

Primary malignant lymphoma of the urinary bladder: report of three cases and review of the literature.

We report three cases of a primary malignant lymphoma of the urinary bladder. The radiological features revealed a sessile mass of the lateral wall for one case, a circumferential thickening in the second, and two separated masses of the bladder wall in the last case. Primary malignant lymphoma of the urinary bladder is extremely rare. From a review of the literature, the clinical and radiological findings are discussed. In this paper we report the first case of urinary bladder lymphoma presented on CTas multiple masses.

Aged↗
PubMed1999

Intraluminal duodenal diverticulum: radiological and endoscopic ultrasonography findings of an unusual cause of acute pancreatitis.

Intraluminal duodenal diverticulum is a rare congenital web of membrane which may be symptomatic when it becomes distended. This report describes a case revealed by presenting as an acute pancreatitis. The radiological findings are reported. The findings at CT, upper gastro-intestinal series, endoscopic ultrasound and endoscopic retrograde cholangiopancreatography are described and differential diagnostic features from choledochocele and duodenal duplication are discussed. By endoscopic ultrasonography, observation of a thin wall, without different layers such as choledochocele or duodenal duplication, may be useful for diagnosis.

Acute Disease↗
PubMed1999

Pulmonary arterial resistance: noninvasive measurement with indexes of pulmonary flow estimated at velocity-encoded MR imaging--preliminary experience.

Cardiac output and pulmonary vascular resistance (PVR) were measured in 19 patients by means of catheterization of the right side of the heart. Results were compared with the cardiac output and indexes of pulmonary arterial blood flow estimated with velocity-encoded magnetic resonance (MR) imaging. Correlations were good between estimates with right-sided heart catheterization and those with velocity-encoded MR imaging. By providing accurate pulmonary arterial blood flow measurements, velocity-encoded MR imaging allowed distinction of patients with high PVR from subjects with normal PVR.

Adult↗
PubMed1999

[Emphysematous pyelonephritis: apropos of 4 cases].

PURPOSE: The propose of this study was to describe the imaging findings in four patients with emphysematous pyelonephritis and to perform a review of the literature. MATERIAL AND METHODS: Four cases of emphysematous pyelonephritis are presented. US and CT examinations were available for all patients. RESULTS: Gas within the kidney may be diagnosed by plain film or rarely by ultrasound, but its location and its extent are best evaluated by CT. A review of the literature shows that emphysematous pyelonephritis is a rare and life-threatening infection typically occurring in diabetic patients. CONCLUSION: CT is useful for diagnosing emphysematous pyelonephritis, especially when symptoms fail to resolve promptly with medical therapy.

Adult↗
PubMed1997

Acceleration mapping by Fourier acceleration-encoding: in vitro study and initial results in the great thoracic vessels.

Acceleration mapping can be conducted by replacing the bipolar gradient pulse of a velocity mapping sequence by a tripolar pulse. However, since the acceleration encoding pulse is longer, the image quality is altered by the requirement of a long echo time. Since Fourier encoding velocity imaging has been shown to be robust, this velocity mapping method was transformed into an acceleration mapping method. Four steps of the tripolar acceleration encoding gradient pulse were applied successively; acceleration was then obtained by Fourier transform after zero-filling. The accuracy of the method was assessed with a phantom giving a pulsatile flow. Acceleration maps of the ascending aorta and pulmonary artery were obtained in 10 healthy volunteers. The acceleration values measured were in the range of known physiologic values. The feasibility of Fourier encoding acceleration imaging was also demonstrated in four patients.

Adolescent↗
PubMed1995

[Morphological and functional study of pulmonary arteries by MRI].

This article presents an exhaustive review of MRI in the assessment of the pulmonary arteries (sequences, normal results, clinical signs of the main diseases). Its current preferential indications are: the study of the main pulmonary artery trunks (primary tumours, proximal embolism, caliber abnormalities, anatomical relations with central tumours), the assessment and post-treatment follow-up of pulmonary arterial malformations. Angio-MRI is currently being developed and, in the near future, should allow the reliable diagnosis of pulmonary embolism and will therefore be indicated alongside spiral computed tomography. MRI also allows functional assessment of the right circulation (measurements of circulatory velocity and flow rates). It should rapidly become an examination of choice in the haemodynamic follow-up of patient with pulmonary hypertension and transplant recipients and as an evaluation tool for new drugs.

Humans↗