Biomedical subjects
Publications and source records attributed to P Demaerel.
The MRI findings at 1.5 Tesla of central pontine myelinolysis in 2 alcoholic patients are reported. The lesion was confined to the pons in both cases, with strong hyperintensity on T2-weighted and hypointensity on T1-weighted images. In both cases MRI revealed typical symmetrical sparing of the ventrolateral tracts in the pons.
Thirty nine patients with one or more focal hepatic lesions were examined by contrast enhanced computed tomography (CE-CT) and magnetic resonance imaging (MRI). A variety of pulse sequences--spin echo (SE), gradient echo (GE) and inversion recovery (IR)--have been reported in the literature on MRI concerning the detection and characterization of liver tumors. Multiple studies have compared MRI at different field strengths to CT. As controversy still exists concerning the optimal pulse sequence on MRI, CE-CT has been compared to T2 weighted SE sequence in this study. CT, as well as MRI, identified abnormalities in liver parenchyma in all patients. As far as detection of hepatic lesions is concerned, MRI and CE-CT were equal in 35 cases and MRI was superior in the other four cases. However, CT remains the examination of choice for detection of focal lesions, due to the short examination time, the low cost and the superiority in detection of extrahepatic pathology.
A case of Moya-Moya disease confirmed by cerebral angiography in a 10-year-old girl is reported. Hypertrophic collateral circulation is easily visualized by MRI. MR angiography very accurately demonstrated the vascular obstruction and the collateral circulation. As MR angiography is not invasive, it promises to become a valuable alternative to conventional angiography in the diagnosis of Moya-Moya.
A case of meningeal cyst of the spinal canal in the lumbosacral region is described. A CT scan showed a soft tissue mass associated with bone erosion. Myelography and computerised tomographic myelography revealed a cyst filling with contrast and thus CSF containing. The diagnosis of meningeal cyst was confirmed in a non-invasive way by MRI showing a mass with the same signal intensities as CSF on both T1 and T2 weighted images. Final characterisation of meningeal cysts in one of the three categories comprising spinal extradural meningeal cyst without spinal nerve root fibers (type I), spinal extradural meningeal cyst with spinal nerve root fibers (type II) and intradural meningeal cyst (type III) is impossible without operative inspection and histological examination.
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A series of 18 patients with diarrhoea and positive stool cultures for Campylobacter jejuni is presented. The most important radiological features were thickening of ileal mucosal folds, of interhaustral indentations and of the ileocaecal valve, lymphoid hyperplasia and microulcerations. Radiology, as well as endoscopy, are both nonspecific in Campylobacter jejuni enterocolitis. The importance of radiology is to exclude more typical features of other causes of inflammatory bowel diseases. Moreover, before the result of the stool culture is available, the radiological features should suggest the suspicion of an acute infectious enterocolitis by Campylobacter jejuni as possible diagnosis.
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The first clinical results of using superparamagnetic ferrite particles as a tissue-specific contrast agent for MR of the liver are reported at high fields (1.5 T). Fifteen patients with proved secondary liver malignancies were studied with plain and contrast-enhanced MR. Superparamagnetic iron oxide was administrated IV in a dose of 20 mumol/kg. Intermediate TR, 820/30, 60 (TR/TE), and long TR, 2200/22, 70, spin-echo sequences were used before and 1 hr after injection of contrast material. Before injection, the largest number of lesions (437) was detected with the T2-weighted sequence. Lesion-to-liver contrast, expressed as the difference between the tumor and liver signal-to-noise, improved after ferrite administration in both sequences from -1 to 20 and from 7 to 15 for the 820/30, 60 sequence and from 9 to 34 and 15 to 21 for the 2200/22, 70 sequence. Despite this significant improvement in terms of the number of lesions detected, contrast-enhanced images did not show significantly more metastases than the unenhanced T2-weighted images did (383, 421, 407, and 407 vs as many as 437, respectively). In this limited study at 1.5 T, the benefit of ferrite enhancement was only marginal when postcontrast images were compared with heavily T2-weighted precontrast scans.
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A case of intrapelvic neurofibroma is presented in a patient with neurofibromatosis. Magnetic resonance imaging proved to be very sensitive in the demonstration and delineation of the tumoral pelvic mass and the detection of smaller subcutaneous lesions. Direct coronal and sagittal images provided important information to the surgeon to evaluate the cranial and caudal extension and the anatomic boundaries of the lesion.
A case of spontaneous dissection of the cervical internal carotid artery documented by angiography and MRI is reported. Angiography showed an irregular stenosis of the upper part of the cervical internal carotid artery extending up to the base of the skull, suggestive of spontaneous dissection. The diagnosis was confirmed beyond doubt by MRI which showed a sub-intimal collection of blood with a typical hyperintense appearance.
MRI and CT were performed in 16 patients with 17 acoustic neurinomas. MRI was superior to CT in the detection of small acoustic neurinomas, in the demonstration of intracanalicular extension and in the differentiation with cerebellopontine angle meningiomas. Overall advantages of MRI over CT included better tissue contrast, absence of bone artifacts and easy multiplanar imaging.
Magnetic Resonance Imaging (MRI) findings in 22 patients with lesions of the globe were examined. There were 16 cases of malignant uveal melanoma, 2 cases of retinoblastoma, 3 cases of hemorrhagic choroidal detachment and 1 case of senile macula degeneration. MRI adequately depicted the lesions in 20 cases. In two cases MRI findings were unconclusive due to movement artifacts of the eye globe. Fourteen out of 16 uveal melanomas displayed typical T1 and T2 shortening. In the two other cases the hypointense aspect on T2-weighted images was less pronounced due to a lesser amount of melanin in the lesions as demonstrated by subsequent histology. Unlike with CT, the tumoral lesions could clearly be differentiated from subretinal exudate. The case of senile macula degeneration, two retinoblastomas and two cases of hemorrhagic choroidal detachment had the same MRI characteristics as melanomas.
A patient with a paraprosthetic-sigmoid fistula following complicated aortic abdominal surgery is reported. Computed tomography confirmed the diagnosis by demonstrating inflammatory tissue around the left limb of the prosthesis in close contact with the sigmoid.
Postoperative bile duct obstruction with subsequent stone formation and infection led to atrophy of the ipsilateral lobe and portal vein obstruction, which promoted further atrophic changes. The compensatory increase in hepatic arterial blood flow resulted in an early enhancement of the atrophic lobe on CT after intravenous contrast medium injection.
Twenty patients [15 men, 5 women, 19-71 years old (mean 52 years)] highly suspected of having tumoral liver pathology were prospectively studied with motion compensated T2-weighted spin echo (SE) [repetition time (TR) 2,200 ms, echo time (TE) 90 ms] and Gd-DOTA enhanced gradient echo fast low angle shot [TR 60 ms, TE 10 ms, angle 30 degrees) sequences. The final diagnoses were hemangioma (five), hepatocellular carcinoma (four), focal nodular hyperplasia (one), adenoma (one), metastasis (two), abscess (two), echinococcal cyst (one), tumor of unknown origin (three), cirrhosis (one). Contrast enhanced images were obtained during the early vascular phases after intravenous bolus injection of Gd-DOTA at a dose of 0.1 mmol/kg (0.2 ml/kg). After Gd-DOTA, positive contrast enhancement was seen in 11 cases, negative enhancement in 4, and nonenhancement in 6. Contrast patterns were similar to contrast enhanced CT. In terms of visibility of lesions, the unenhanced motion-compensated T2 SE sequences were superior to the nonenhanced gradient echo sequences in 12 patients and equal in 8. After gadolinium enhancement, T2-weighted SE images were superior to the postcontrast gradient echo images in eight cases, equal in eight and inferior in four cases.
Fifty patients with newly diagnosed, untreated intracranial tumors were examined with 1H nuclear magnetic resonance single-volume spectroscopy (MRS) using a 1.5 T whole-body MR system. Prior to the MRS, contrast enhanced MR and/or CT imaging studies were carried out. Histological verification was obtained in all patients except one. All tumor spectra revealed distinct abnormalities as compared with the normal brain spectra. Although most meningiomas showed a rather characteristic spectral pattern, generally features specific for the various tumor types were not observed. For instance, though a strong lactic acid signal was seen in most malignant tumors, this signal was also evident in five benign neoplasms.
Gadolinium-enhanced MR was performed in 28 patients with 17 supratentorial and 11 cerebellar venous angiomas. The use of gadolinium allowed detection of 9 of 28 venous angiomas (32%) that were not visible before gadolinium or which were only recognized in retrospect. Before gadolinium the peripheral medullary veins that are typical for these venous malformations were only visualized in 4 of 17 (23%) supratentorial and in 5 of 11 (45%) cerebellar lesions, for a total of 9 of 28 (32%) venous angiomas. After intravenous administration of gadolinium these veins were seen in 27 of 28 (96%) venous angiomas. Extension of the lesions to the wall of the ventricles was seen in 24 of the 28, 16 of 17 supratentorial and 8 of 11 cerebellar, lesions after gadolinium. This information was missed on plain MR in 6 of these lesions. The type of venous drainage, either superficial or deep, could be determined by gadolinium-enhanced MR in all cases where angiography was available for comparison. Before gadolinium this information was not available in eight patients. The intravenous administration of gadolinium adds significant information in the MR study of venous angioma.