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Biomedical subjects

A Guermazi

Publications and source records attributed to A Guermazi.

At least 19 recordsLinked to original sources
PubMed2003

Metallic artefacts in MR imaging: effects of main field orientation and strength.

AIM: To determine the effect of metallic implant positioning on magnetic resonance (MR) imaging artefacts, and to determine the optimal imaging parameters for minimization of metallic artefacts. MATERIALS AND METHODS: In a phantom and in three joints with non-ferromagnetic metallic implants imaged at 1.5 and/or at 0.2 T, we examined the influence of the static magnetic field (B(0)) strength and orientation, frequency-encoding direction, and type of imaging sequence on metallic artefacts. RESULTS: The impact of artefacts caused by metallic objects depends mainly on the relationship between the anatomy of interest and the orientation of the object relative to the direction of B(0). The main field strength plays a less important role, but its orientation depends on the type of MR imager. CONCLUSION: MR artefacts can be easily minimized by optimally positioning patients with metallic implants in the magnet. Knowledge of how this influences MR imaging is helpful in patient selection and guiding limb positioning.

Artifacts↗
PubMed2003

[Fatty replacement of the pancreas in a patient with asymptomatic pulmonary cystic fibrosis].

The authors report the case of a 26-year-old woman with hepatomegaly, who had recurrent and progressive nausea and abdominal pain. Computed tomography and magnetic resonance imaging demonstrated fatty replacement of the entire pancreas resulting from cystic fibrosis. The pulmonary disease was totally asymptomatic. Fatty replacement of the pancreas is the most frequent pattern in older patients with cystic fibrosis. This pattern correlates with pancreatic exocrine dysfunction.

Adipose Tissue↗
PubMed2001

Imaging of MALT lymphomas.

The broad category of non-Hodgkin's lymphoma includes a large variety of different diseases including indolent as well as aggressive lymphomas. Mucosa-associated lymphoid tissue (MALT) lymphoma arises in the extranodal mucosal lymphoid tissue and has only been recognised as a distinct entity in recent years. It affects one or several extranodal structures such as the stomach, the lung, the eye and salivary glands. The lymphoma is generally of low grade and has indolent course. The aim of this article is to exemplify the most common radiological patterns of MALT lymphoma.

Adult↗
PubMed2001

Cerebral and spinal cord involvement resulting from invasive aspergillosis.

Although central nervous system involvement in disseminated aspergillosis is known to occur in immunocompromised patients, particularly after bone marrow transplantation, localized involvement of the spinal cord is exceedingly rare. In this report we present and illustrate detailed imaging findings of central nervous system invasion by Aspergillus fumigatus in a 30-year-old woman, with emphasis on the spinal cord involvement.

Adult↗
PubMed2001

Multiple glioblastomas: CT and MR features.

The aim of this study was to analyze the CT and MR features of multiple glioblastomas, and to determine the best imaging modality for the initial diagnosis. The CT (four exams) and MR imaging (eight exams) of eight patients with proven multiple glioblastomas were reviewed by two neuroradiologists. The lesions were always hypo- or isodense on CT and hyperintense on T2-weighted images (100%). They were usually hypo- or isointense on T1-weighted images (90%). Edema and mass effect were very variable. After contrast media administration, the enhancement was mostly strong (71% on CT and 70% on MR), often either heterogeneous or ring-like. The different lesions of a patient often had a different pattern on MR (75% of cases). Meningeal or ventricular enhancement, suggestive of a possible way of dissemination, was rare. In case of multiple cerebral masses, multiple glioblastomas should be considered as a possible diagnosis in addition to the better known diagnosis of brain metastases, abscesses, or multifocal lymphomas. Moderate edema and mass effect on MR associated with strong and heterogeneous enhancement are suggestive of feature of multiple glioblastomas. Magnetic resonance allows rarely the visualization of a dissemination route.

Brain↗
PubMed2001

Is it wise to eliminate lymphography from the staging of Hodgkin's disease?

We believe that lymphography and CT are complementary rather than mutually exclusive techniques for the diagnosis and staging of HD. Unfortunately, it seems that many radiologists and clinicians disregard the ability of lymphography to provide qualitative information on lymph node architecture, which is not available by CT. The use of lymphography is declining in several teaching centers throughout the world. This makes it difficult for young radiologists to acquire the skills needed to perform and interpret lymphographies successfully. In turn, radiologists who have little experience with lymphography are less likely to use the technique. Because most of the treatment-related morbidity in HD is dose-related, and because lymphography helps to avoid over- and undertreatment, we believe that high-quality lymphography continues to have a significant role in the staging of selected HD patients. Moreover. lymphography may reduce both the cost of management and the morbidity rate in many HD patients. One solution would be to continue to use lymphography in a small number of institutions specialized in the management of HD.

Hodgkin Disease↗
PubMed2001

[Digital thoracic radiology: devices, image processing, limits].

In a first part, the different techniques of digital thoracic radiography are described. Since computed radiography with phosphore plates are the most commercialized it is more emphasized. But the other detectors are also described, as the drum coated with selenium and the direct digital radiography with selenium detectors. The other detectors are also studied in particular indirect flat panels detectors and the system with four high resolution CCD cameras. In a second step the most important image processing are discussed: the gradation curves, the unsharp mask processing, the system MUSICA, the dynamic range compression or reduction, the soustraction with dual energy. In the last part the advantages and the drawbacks of computed thoracic radiography are emphasized. The most important are the almost constant good quality of the pictures and the possibilities of image processing.

Humans↗
PubMed2000

Image-guided core-needle biopsy in patients with suspected or recurrent lymphomas.

BACKGROUND: It is now commonly admitted that the diagnosis of recurrence of lymphoma can be assessed by image-guided needle biopsy (IGNB). However, the means of obtaining tissue for the original diagnosis of lymphoma is often surgery. The aim of this study was to compare the accuracy of IGNB at the time of diagnosis and at the time of recurrence or progression. METHODS: The authors performed 212 IGNBs on 194 patients who eventually had a diagnosis of lymphoma. One hundred three IGNBs were obtained at original diagnosis and 109 at recurrence or progression. Large-cutting core-biopsy needles, ranging in size from 20 gauge to 14 gauge, were used. Immunohistochemistry studies were performed in all lymphoma cases. RESULTS: A diagnosis of lymphoma with subtyping was obtained in 88% of all cases, in 85% at initial diagnosis, and in 89% at follow-up. Therapy was initiated on the basis of IGNB in 93% of all cases, in 91% at initial diagnosis, and in 94% at follow-up. Benign complications occurred in 7.5% of cases and did not require specific treatment. IGNB was equally effective for making a specific diagnosis of lymphoma and initiating therapy at the time of original diagnosis and at follow-up. CONCLUSIONS: The authors recommend that IGNB be performed as the initial procedure for the diagnosis of lymphoma in the absence of peripheral lymph nodes, either at presentation or at recurrence.

Adolescent↗
PubMed2000

[Role of MRI in the diagnosis of breast diseases].

UNLABELLED: ADVANTAGES AND LIMITATIONS: Magnetic resonance imaging of the breast is probably the most sensitive method for detecting or ruling out breast disease. It is however not as specific as expected. TECHNIQUE: All examinations are performed with and without gadolinium intravenous administration, excepted in the case of silicone implant reconstruction mammoplasty. Dynamic contrast-enhanced MRI sequences are necessary with a permanent balance between temporal resolution, spatial resolution, and signal. MRI of the breast is not indicated as a routine examination in a screening program, neither to improve the specificity of infra-clinic lesions, nor in simply dense breasts without any known risk factor or in circumscribed masses. INDICATIONS: MRI is best used to improved the sensitivity of mammography and sonography in selected patients. The selected indications are: evaluation of the volume and extension of breast lesions evaluation of the therapeutic response after chemotherapy, and detection or exclusion of the local recurrence in patients with breast conservation therapy. PERSPECTIVES: The future indications and perspectives of MRI include interventional breast radiology (MRI-guided core biopsy), and thermocoagulation therapy. It may be interesting for the evaluation of patients with contrast enhanced MRI lesions with normal mammography and sonography, and also in woman with a genetically defined high breast cancer risk.

Biopsy↗
PubMed2000

Restaging with gallium scan identifies chemosensitive patients and predicts survival of poor-prognosis mediastinal Hodgkin's disease patients.

UNLABELLED: Following treatment of mediastinal Hodgkin's disease (HD), residual masses are frequent and gallium scanning has proven to be of value in the evaluation of their specificity (fibrosis or active disease). This study assessed, for relapse and survival, the predictive value of restaging gallium scan of patients with a residual mass on computed tomography scan after induction chemotherapy. Between 1/89 and 12/97, in 53 newly diagnosed HD patients with a residual mediastinal mass, a gallium scan was performed after chemotherapy (3 or 4 courses) and always before consolidative radiotherapy. Characteristics at diagnosis were: nodular sclerosis histology, 89%; bulky mediastinal disease, 79%; B-symptoms, 51%. RESULTS: gallium scan was positive in 16 patients (30%) and negative in 37 (70%). At median follow-up period of 36 months, freedom-from-progression rate was 86% versus 19% (P<0.0001) for patients with negative vs positive gallium scans, respectively. The 5-year overall survival (OS) rate was 68% and differed significantly (P<0.0001) between negative (91%) and positive (25%) gallium scanning groups. The specificity of gallium scanning was 91% and the sensitivity 72% with a positive predictive value of 81% and a negative predictive value of 86%. Evaluation with gallium scan after induction chemotherapy identifies chemosensitive patients among those with poor-prognosis mediastinal HD. Although relapse may occur in patients with negative gallium scan, a postive gallium scan is highly predictive of failure and poor outcome, and treatment should thus be modified.

Adult↗
PubMed2000

[Techniques to improve the accuracy of CT-guided abdominal biopsy].

STUDY AIM: The aim of this paper is to present an overview of the various technical progresses made in the field of CT-guided abdominal biopsies. Recent improvements allowed to markedly increase the efficiency of biopsies and to decrease the number of complications. The main innovations concern the guidance technique itself with the availability of ultra-fast CT systems, the development of automated biopsy systems, which allow to improve the size and quality of tissue samples and numerous technical tricks, allowing an easier access to target lesions, either in patient positioning or in displacement of anatomical structures. A better management of tissue samples favored by a close collaboration with pathologists is also mandatory. The last section of the paper is an overview of the rare complications of CT-guided biopsies.

Abdomen↗
PubMed2000

[Primary malignant melanoma of the esophagus].

Primary malignant melanoma of the esophagus is a rare but aggressive tumor that accounts for less than 0.1-0.2% of all esophageal malignancies. The aim of this study was to report a case of primary malignant melanoma of the esophagus in a 72-year-old woman. The diagnosis was histologically proven, but the patient died despite extensive surgical resection.

Aged↗