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Biomedical subjects

A M De Schepper

Publications and source records attributed to A M De Schepper.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Gadolinium-DOTA enhanced MR imaging of intracranial lesions.

Gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (Gd-DOTA) is the first of a new class of macrocyclic paramagnetic magnetic resonance (MR) contrast agents (gadolinium cryptelates) to be used in clinical practice. Gadolinium-DOTA possesses relaxation properties similar to those of gadolinium diethylene triamine pentaacetic acid (Gd-DTPA). We report our initial clinical experience in 38 patients with intracranial lesions studied with MR before and after injection of Gd-DOTA. Diseases included primary and metastatic brain tumor, cerebral infarct, vascular malformation, meningioma, hemangiopericytoma, schwannoma, and pituitary macroadenoma. Gadolinium-DOTA was administered intravenously in a dosage of 0.1 mmol/kg body weight. All studies were performed on a superconductive 0.5 T system. As compared to noncontrast T1- and T2-weighted images (WI), Gd-DOTA enhanced T1 WI were useful in defining the anatomy of malignant intraaxial tumors (high-grade glioma, metastasis) and in tumor versus edema differentiation. Low-grade gliomas did not enhance; in these cases the precontrast T2-weighted sequence was found to be more informative. In post-operative patients, Gd-DOTA allowed us to demonstrate residual tumor or tumor recurrence. Extraaxial tumors (meningioma, hemangiopericytoma, neuroma) enhanced markedly, presumably reflecting tumor vascularity. In our experience, the use of Gd-DOTA improves the anatomic definition of cerebral lesions and in some cases increases both MR sensitivity and specificity. We found Gd-DOTA to be a well tolerated and effective paramagnetic contrast agent. Gadolinium-DOTA can be considered as an alternative water-soluble MR contrast agent to Gd-DTPA.

Adult↗
PubMedDate not supplied

Influence of magnetic field strength on T2* decay and phase effects in gradient echo MRI of vertebral bone marrow.

OBJECTIVE: The goal of this study was twofold: first, to quantify the influence of magnetic field strength (B0) on T2* and T2susceptibility relaxation rates in vertebral bone marrow; and second, to determine the significance of in-phase/out-of-phase phenomena in GE MRI as a function of TEs at different B0 values. MATERIALS AND METHODS: Magnetic resonance imaging of the spine was performed at 1.5, 1.0, and 0.2 T using a GE sequence (2D-FLASH) with variable TE. Vertebral body signal intensities were measured and plotted against TE values. These curves were used to calculate T2* decay of bone marrow at different B0 values. RESULTS: At all field strengths, we observed exponential signal decay, modulated by a cosine function, the periodicity of which was proportional to B0. The T2* values of vertebral bodies were 9.7 +/- 1.8 ms at 1.5 T, 17.2 +/- 2.4 ms at 1.0 T, and 53 +/- 5 ms at 0.2 T. True T2 relaxation time (independent of field strength) was 62 +/- 4 ms. The T2susceptibility was 11.7 ms at 1.5 T, 24.8 ms at 1.0 T, and 585 ms at 0.2 T. CONCLUSION: We conclude that at low B0, susceptibility effects become less important and T2* approaches true T2 relaxation.

Adult↗
PubMedDate not supplied

Polypoid and pseudopolypoid lesions of inflammatory bowel disease: diagnosis on double-contrast enema.

The radiological and pathological features of ulcerative colitis (UC) and Crohn's disease (CD) are well known for most radiologists and gastroenterologists but on double-contrast enema, polypoid and pseudopolypoid manifestations of inflammatory bowel disease (IBD) often remain a source of major confusion. Inflammatory polyps project above the level of the surrounding mucosa. Pseudopolyposis is seen when extensive ulceration of the mucosa down to the submucosa results in scattered circumscribed islands of relatively normal mucosal remnants. Postinflammatory polyps reflect a non-specific healing of undermined mucosal and submucosal remnants and ulcers, and are mostly multiple. They have no malignant potential. Patients with long-standing UC and CD are at increased risk for developing colorectal carcinoma. Dysplasia is a precancerous histologic finding and is frequently seen in colitic colons at high risk for carcinoma. Dysplasia may be found in a radiographically normal appearing mucosa or it may be accompanied by a slightly raised mucosal lesion, a so-called dysplasia-associated lesion or mass (DALM lesion) and as a consequence radiographically detectable. Because differentiation of adenocarcinoma and dysplasia from inflammatory or postinflammatory polyps is sometimes difficult or impossible on double-contrast enema, endoscopy and biopsy are necessary for making a final diagnosis.

Barium Sulfate↗
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The value of medical imaging in uncomplicated and complicated Barrett's esophagus.

Barrett's esophagus is an acquired condition characterized by a progressive columnar metaplasia of the distal esophagus caused by longstanding gastroesophageal reflux and reflux esophagitis. Barrett's esophagus is a premalignant condition associated with a significantly increased risk of developing esophageal adenocarcinoma. The purpose of this article is to provide an overview of the radiologic aspects of Barrett's esophagus and esophageal adenocarcinoma. Review of the literature shows that some findings on esophagography that are relatively specific for Barrett's esophagus are not sensitive, while others that are sensitive have a low specificity. Specific radiologic features allowing a confident diagnosis of Barrett's esophagus are a high esophageal stricture or ulcer associated with a hiatal hernia and/or gastroesophageal reflux. A reticular mucosal pattern is a relatively specific sign particularly if located adjacent to a stricture and is highly suggestive of Barrett's esophagus. Unfortunately, these findings are only present in a minority of cases. More common but nonspecific findings include gastroesophageal reflux, hiatal hernia, reflux esophagitis and/or peptic stricture in distal esophagus. These findings may also be present in patients with uncomplicated reflux disease. Barrett's esophagus carries a risk of malignant change. Early adenocarcinoma may appear as a plaque-like lesion or with focal irregularity, nodularity, and ulceration of the esophageal wall. Invasive adenocarcinoma may be seen as an infiltrating ulcerated mass. The radiologic diagnosis of Barrett's esophagus is limited by lack of criteria that are both sensitive and specific. The major value of double-contrast esophagography is its ability to classify patients into high risk (high stricture, ulcer or reticular pattern), moderate risk (esophagitis and/or distal peptic strictures), and low-risk (absence of esophagitis or stricture) for Barrett's esophagus determining the relative need for endoscopy and biopsy. Endoscopy and biopsy are generally advocated to make a definitive diagnosis. Endoscopic ultrasound plays a role in the early detection of invasive carcinoma and the staging of proven carcinoma but has no role in the surveillance of Barrett's esophagus.

Adenocarcinoma↗
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Hepatobiliary cystadenoma with mesenchymal stroma mimicking hydatid cyst. Report of a case.

We report on a case of hepatobiliary cystadenoma with mesenchymal stroma in a 44-year-old Caucasian woman who presented with upper abdominal discomfort. Ultrasound (US) and computed tomography (CT) showed a cystic mass resembling hydatid cyst. Endoscopic retrograde cholangiography (ERC) demonstrated communication with the left hepatic duct. At surgery, a cystic mass with communication to the left hepatic duct was found and resected en bloc with a margin of normal liver tissue. Histological examination showed a hepatobiliary cystadenoma with mesenchymal stroma.

Adult↗
PubMedDate not supplied

Trauma of the pediatric ankle and foot.

This article presents a brief overview of the injuries to the ankle and foot encountered in children and adolescents. Trauma to the ankle or foot may result from acute, chronic, or repetitive forces. The role of the different imaging modalities in the assessment of ankle and foot trauma in the growing patient is discussed. Plain radiographs remain the mainstay in the diagnosis of most acute traumas, whereas CT may be helpful to unravel the complex anatomy of certain fractures like the triplane or juvenile Tillaux fracture. In the evaluation of chronic injuries, including osteochondrosis dissecans and osteonecrosis, MRI is evolving as the modality of choice.

Ankle Injuries↗
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Glenoid hypoplasia.

Explore the source record for details and available documents.

Adult↗
PubMedDate not supplied

Paraspinal cervical calcifications associated with scleroderma.

Although soft tissue calcifications are well known to occur as a late manifestation in scleroderma, symptomatic paraspinal calcinosis is very rare. Clinically, patients present with focal neck pain, weakness or radiculopathy, and decreased range of motion of the neck. We describe the imaging features of a rare case of cervical paraspinal calcinosis in a 74-year-old woman with long-standing scleroderma. Standard radiography is usually sufficient to confirm the diagnosis, but CT-scan allows a more precise location of the calcifications around the facet joints, sometimes with associated erosions. The advantage of MRI is to evaluate the possible intraspinal extension of the calcifications in case of focal neurological symptomatology.

Aged↗
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Pattern recognition of degenerative disorders in the lumbar spine. Guidelines to MR image interpretation.

Interpreting MR images of the lumbar spine remains a formidable diagnostic challenge, especially in patients with degenerative changes. What are the pertinent findings? Which abnormalities are clinically relevant? Which changes should be viewed as normal aging? The purpose of this presentation is to present a standardized 7-step approach towards interpreting MR images of the degenerative lumbar spine.

Humans↗
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CT-guided percutaneous needle biopsy in spine lesions.

Vertebral bone biopsy is an accurate, rapid, and cost-effective method to diagnose benign and malignant spine lesions. The major complications are uncommon. Nondiagnostic or insufficient specimens are encountered in less than ten per cent. The accuracy of the biopsy depends on the location and type of the lesion, needle system, and biopsy route. The major indications are focal lesions with non-specific medical imaging findings, to exclude metastasis in patients with known primary malignancy, lesion without response to treatment, no clinical improvement in children with diskitis after six weeks of therapy to exclude occult tumor and extreme pain due to vertebral collapse. If histology yields only peripheral blood elements in an obviously destructive mass, biopsy can be repeated, by directing at a slightly different area of the lesion. No more than three percutaneous biopsies of the same lesion should be performed.

Adult↗