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Biomedical subjects

Paul M Parizel

Publications and source records attributed to Paul M Parizel.

18 recordsLinked to original sources
PubMed2006

MRI features of focal splenic lesions in patients with disseminated tuberculosis.

OBJECTIVE: The aim of this study is to describe the MRI features of focal splenic lesions in patients with disseminated tuberculosis. CONCLUSION: Tuberculous focal splenic lesions are small, multiple, and most often associated with splenomegaly. Signal intensities vary on both T1- and T2-weighted images. Two different enhancement patterns are noted: peripheral enhancement and gradual peripheral enhancement with complete fill-in.

Adult↗
PubMed2005

Meningoencephalitis caused by Streptococcus pneumoniae: a diagnostic and therapeutic challenge. Diagnosis with diffusion-weighted MRI leading to treatment with corticosteroids.

Streptococcus pneumoniae is a common cause of bacterial meningitis but only rarely causes other infections such as brain abscess, encephalitis, encephalomyelitis or meningoencephalitis. We report on three adult patients with meningoencephalitis caused by S. pneumoniae. In all three, CT and MRI revealed widespread brain lesions, suggesting extensive parenchymal injury. Diffusion-weighted MRI showed lesions with restricted diffusion, reflecting local areas of ischaemia with cytotoxic oedema secondary to an immunologically mediated necrotising vasculitis and thrombosis. High levels of markers of neuronal, glial and myelin damage were found in the cerebrospinal fluid. According to the literature, brain parenchyma lesions in adults with pneumococcal meningoencephalitis are often associated with death or severe neurological deficit. Our patients were treated with pulse doses of glucocorticoids: this resulted in dramatic clinical improvement and an excellent final neurological recovery.

Adult↗
PubMed2005

Treatment of intraventricular hemorrhage with intraventricular administration of recombinant tissue plasminogen activator A clinical study of 18 cases.

OBJECTIVE: Intraventricular hemorrhage is associated with a very poor outcome. Simple external ventricular drainage alone has not resulted in a decline of mortality. The aim was to study the effect of direct intraventricular administration of recombinant tissue plasminogen activator (rtPA). PATIENTS AND METHODS: A retrospective series of eighteen adult patients with severe intraventricular hemorrhage, admitted to our university hospital, was studied for the effect of direct intraventricular administration of recombinant tissue plasminogen activator (rtPA). rtPA was administered in a dosage of 2mg. The injection was repeated at 12h intervals until serial CT scans showed a substantial reduction of intraventricular blood. RESULTS: The total of rtPA doses per patient ranged from 2 to 32mg. Seven out of 18 patients showed good neurological recovery, 4 died. Only one patient had a complication which could be directly attributed to the intraventricular thrombolytic therapy. CONCLUSION: We conclude that the procedure of intraventricular administration of a thrombolytic agent, i.e. rtPA, seems effective in lysis of the intraventricular hematoma and may, therefore, improve outcome.

Adult↗
PubMed2005

Feasibility of tissue magnetic resonance imaging: a pilot study in comparison with tissue Doppler imaging and invasive measurement.

OBJECTIVES: This research was intended to determine the feasibility of tissue magnetic resonance (MR) imaging in comparison with tissue Doppler imaging and its potential implications for the estimation of filling pressure, in comparison with invasive measurement. BACKGROUND: Evaluation of diastolic function using MR imaging is commonly confined to the study of transmitral flow. However, transmitral flow is unreliable for the estimation of left ventricular (LV) filling pressures in hypertrophy and normal systolic function. Normalizing early mitral velocity (E) for the influence of myocardial relaxation by combining E with early diastolic mitral septal tissue velocity (Ea) provides better Doppler estimates of filling pressures. METHODS: Eighteen patients with hypertensive heart disease (LV mass index: 114 +/- 21 g/m(2)), absence of valvular regurgitation, and with normal or mildly reduced systolic function (LV ejection fraction: 57.6 +/- 6.5%) referred for cardiac catheterization, underwent consecutive measurement of mitral flow and septal tissue velocities with phase-contrast MR and Doppler. These data were compared with mean pulmonary capillary wedge pressure (PCWP). RESULTS: There was a strong relation between MR (11.6 +/- 4.3) and Doppler-assessed (12.1 +/- 3.5) E/Ea (95% confidence interval of -1.5 to 0.5) (r = 0.89, p < 0.0001). In addition, E/Ea related strongly to invasively measured PCWP (MR: r = 0.80, p < 0.0001 and Doppler: r = 0.85, p < 0.0001). CONCLUSIONS: Tissue MR imaging is a feasible method to assess Ea. Combining E and Ea allowed similar estimation of filling pressure by MR and Doppler, in good agreement with invasive measurement. The potential confounding effect of valvular regurgitation needs further study.

Blood Flow Velocity↗
PubMed2005

Imaging in spinal trauma.

Because it may cause paralysis, injury to the spine is one of the most feared traumas, and spinal cord injury is a major cause of disability. In the USA approximately 10,000 traumatic cervical spine fractures and 4000 traumatic thoracolumbar fractures are diagnosed each year. Although the number of individuals sustaining paralysis is far less than those with moderate or severe brain injury, the socioeconomic costs are significant. Since most of the spinal trauma patients survive their injuries, almost one out of 1000 inhabitants in the USA are currently being cared for partial or complete paralysis. Little controversy exists regarding the need for accurate and emergent imaging assessment of the traumatized spine in order to evaluate spinal stability and integrity of neural elements. Because clinicians fear missing occult spine injuries, they obtain radiographs for nearly all patients who present with blunt trauma. We are influenced on one side by fear of litigation and the possible devastating medical, psychologic and financial consequences of cervical spine injury, and on the other side by pressure to reduce health care costs. A set of clinical and/or anamnestic criteria, however, can be very useful in identifying patients who have an extremely low probability of injury and who consequently have no need for imaging studies. Multidetector (or multislice) computed tomography (MDCT) is the preferred primary imaging modality in blunt spinal trauma patients who do need imaging. Not only is CT more accurate in diagnosing spinal injury, it also reduces imaging time and patient manipulation. Evidence-based research has established that MDCT improves patient outcome and saves money in comparison to plain film. This review discusses the use, advantages and disadvantages of the different imaging techniques used in spinal trauma patients and the criteria used in selecting patients who do not need imaging. Finally an overview of different types of spinal injuries is given.

Aged↗
PubMed2004

MR angiography of the intracranial vessels: technical aspects and clinical applications.

Evaluation of the intracranial circulation provides valuable information in the diagnosis and prognosis of various intracranial abnormalities and may influence patient management. Technical advances in magnetic resonance angiography (MRA) have improved the accuracy of this technique in various clinical situations, such as aneurysms, arterial and venous steno-occlusive diseases, vascular malformations, inflammatory arterial diseases, preoperative assessment of the patency of dural sinuses, and congenital vascular abnormalities. In many centers, MRA has replaced conventional digital subtraction angiography in screening for intracranial vascular disease, because of its non-invasive and non-ionizing character. Several MRA techniques have been developed for the imaging of the intracranial vascular system, such as time-of-flight MRA (TOF MRA), phase-contrast MRA (PC MRA), and more recently contrast-enhanced MRA (CE MRA). In the evaluation of steno-occlusive disease, the three-dimensional (3D) TOF-MRA technique is recommended for arterial evaluation, and the 2D TOF or 2D PC-MRA technique for venous evaluation. For the evaluation of aneurysms and arteriovenous malformations (AVMs), we recommend the 3D CE-MRA technique, especially dynamic sequences in case of AVM. In this review, the technical aspects, limitations, and optimization of these MRA techniques will be discussed together with their indications in intracranial disease.

Cerebrovascular Disorders↗
PubMed2004

Accuracy of MRI in characterization of soft tissue tumors and tumor-like lesions. A prospective study in 548 patients.

The purpose of our study was to assess prospectively the value of MRI in characterization of soft tissue tumors (STT) and soft tissue tumor-like lesions in a multi-institutional setting by a group of experts. The material consisted of 548 untreated and proven STT or tumor-like lesions originating from a multi-institutional database of STT in which 930 consecutive patients with STT examined by MRI were registered between 1 January 2001 and 28 April 2003. Based on MRI findings, a suitably ordered differential diagnosis was made in consensus by two radiologists (J.L.M.A.G and A.M.D.S). MRI diagnoses were compared with histology results (455 cases, 83%) and/or 6-month follow-up (93 cases, 17%) as reference standards. The correlation between the MRI and histological diagnosis and between the radiological and histological phenotype were statistically determined. One hundred twenty-three patients presented with a malignant STT; 425 patients presented with a benign one. Concerning differentiation between malignant and benign lesions (dignity), a sensitivity of 93%, specificity of 82%, negative predictive value (NPV) of 98% and positive predictive value (PPV) of 60% with accuracy of 85% were obtained. Concerning phenotype characterization, if only the first MRI diagnosis was taken into account, a sensitivity of 67%, specificity of 98%, NPV of 98%, PPV of 70% and accuracy of 96% were obtained. For benign lesions, sensitivity of 75%, specificity of 98%, NPV of 98%, PPV of 76% and accuracy of 97% were obtained. The phenotype's definition of malignant STT had a sensitivity of 37%, a specificity of 96%, NPV of 96%, PPV of 40% and an accuracy of 92%. A correct diagnosis compared with histological assessment was proposed in 227(50%) of the 455 histologically confirmed cases. Despite non-quantified MR parameter evaluation, the results of our prospective study were better than those reported in previous studies and demonstrated the need for a centralized approach to such rare pathology.

Adolescent↗
PubMed2003

Cortical hypoxic-ischemic brain damage in shaken-baby (shaken impact) syndrome: value of diffusion-weighted MRI.

Shaken-baby syndrome (SBS) is a type of child abuse caused by violent shaking of an infant, with or without impact, and characterized by subdural hematomas, retinal hemorrhages, and occult bone fractures. Parenchymal brain lesions in SBS may be missed or underestimated on CT scans, but can be detected at an earlier stage with diffusion-weighted MRI (DW-MRI) as areas of restricted diffusion. We demonstrate the value of DW-MRI in a 2-month-old baby boy with suspected SBS. The pattern of diffusion abnormalities indicates that the neuropathology of parenchymal lesions in SBS is due to hypoxic-ischemic brain injuries, and not to diffuse axonal injury.

Brain↗
PubMed2003

A brief review of parallel magnetic resonance imaging.

Since the 1980s, the implementation of fast imaging methods and dedicated hardware for MRI scanners has reduced the image acquisition time from nearly an hour down to several seconds and has therefore enabled a widespread use of MRI in clinical diagnosis. Since this development, the greatest incremental gain in imaging speed has been provided by the development of parallel MRI (pMRI) techniques in late 1990s. Within the past 2 years, parallel imaging methods have become commercially available, which means that pMRI is now available for broad clinical use. In the clinical routine, virtually any MRI method can be enhanced by pMRI, allowing faster image acquisitions without any increased gradient system performance. In some cases pMRI can even result in a significant gain in image quality due to this faster acquisition. In this review article, the advantages and the disadvantages of pMRI in clinical applications are discussed and examples from many different daily applications are given.

Brain Neoplasms↗
PubMed2003

The interutricular distance determined from external landmarks.

Knowledge of the exact distance between the utricles is important in new vestibular tests, such as the unilateral centrifugation (UC) test for the unilateral examination of the utricles. During this test, subjects are rotated at constant velocity and simultaneously laterally displaced along an interaural axis so that one labyrinth becomes aligned with the axis of rotation. When the axis of rotation crosses precisely through one labyrinth, only the opposite labyrinth is stimulated. To achieve this setup, precise knowledge of the interutricular distance is needed. The purpose of this study is to investigate the correlation between the interutricular distance (IUD), measured on T2-weighted magnetic resonance images, and specific external measures of head dimensions such as distance nasion-inion, intermastoid distance (IMD), distances between the temporomandibular joints and between the lateral margins of the orbits. Data have been collected in a series of 50 subjects (25 men and 25 women). On MR images we found a mean IUD of 7.22 cm (SD = 0.42 cm). There was a strong correlation between the IUD measured on MR images and the intermastoid distance. A linear combination of the IMD, nasion-inion distance and height of the subjects could predict the IUD very satisfactory (R = 0.85, adjusted R2=0.723). We also determined a measure of eccentricity of the vestibular labyrinths. The 95% prediction interval for the asymmetry appeared to be less than 4.3%.

Adolescent↗
PubMed2001

Brainstem hemorrhage in descending transtentorial herniation (Duret hemorrhage).

OBJECTIVES: To review clinical and radiological findings in patients with Duret hemorrhages and to discuss the pathophysiology and differential diagnosis of these lesions. PATIENTS AND METHODS: We reviewed the case records of four patients with Duret hemorrhages who had been admitted to the neurological intensive care unit with supratentorial mass lesions. RESULTS: Descending transtentorial and subfalcine herniations were present in all cases. Three patients were admitted with acute subdural hematoma and one with intraparenchymal hemorrhage. Computed tomography revealed the presence of blood in the mesencephalon and upper pons. Three patients died; one survived with severe disabilities. DISCUSSION: Duret hemorrhages are typically located in the ventral and paramedian aspects of the upper brainstem (mesencephalon and pons). The pathophysiology of Duret hemorrhage remains under debate: arterial origin (stretching and laceration of pontine perforating branches of the basilar artery), versus venous origin (thrombosis and venous infarction). Multifactorial causation seems likely. CONCLUSION: Duret hemorrhages are delayed, secondary brainstem hemorrhages. They occur in craniocerebral trauma victims with rapidly evolving descending transtentorial herniation. Diagnosis is made on computed tomography of the brain. In most cases the outcome is fatal. On the basis of our observations we believe that arterial hypertension and advanced age are risk factors for the development of Duret hemorrhage.

Aged↗
PubMedDate not supplied

Malignant pleural mesothelioma with heterologous osteoblastic elements: computed tomography, magnetic resonance, and positron emission tomography imaging characteristics of a rare tumor.

The imaging findings of a rare mixed type of malignant mesothelioma of the pleura with heterologous bone stroma in a patient without a previous history of asbestos exposure are reported. Imaging findings of this type of bone-forming pleural mesothelioma are scarcely reported in the literature, with only a few case reports describing findings on conventional radiography, computed tomography, and magnetic resonance imaging. To the best of our knowledge, no positron emission tomography imaging characteristics of this type of mesothelioma have been previously reported.

Contrast Media↗