Biomedical subjects
Publications and source records attributed to J Valk.
Magnetic resonance (MR) imaging examinations were performed on a series of seven sets of twins (four monozygotic and three dizygotic) and one set of triplets who were clinically discordant for multiple sclerosis (MS). MR abnormalities were detected in some of the unaffected monozygotic pairs of twins.
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Cross-sectional areas of the jaw muscles were determined by means of magnetic resonance imaging (MRI) in 12 healthy adult male subjects. These findings were compared with the cross-sectional areas of the jaw muscles of the same subjects, obtained by means of computer tomography (CT) in a previous study (Weijs and Hillen, 1985). Significant correlations (r greater than 0.7) were found between the CT and MRI cross-sections of the masseter, medial pterygoid, and temporalis muscles. The low correlation between the CT and MRI cross-sections of the lateral pterygoid muscle could be explained by the different imaging techniques (slice thickness) of MRI and CT scanning. CT and MRI cross-sectional areas of the masseter and medial pterygoid muscle (but not the temporalis muscle) showed highly positive and significant correlations with the maximal voluntary bite force. In living subjects, the cross-sections of the masseter and medial pterygoid muscles can be visualized with CT and MRI. Compared with CT, MRI has some advantages, such as the absence of adverse effects (no radiation) and the excellent soft-tissue imaging. Furthermore, a series of frontal, horizontal, sagittal, and angulated MRI scans can be made without modification of the patient's position, facilitating reconstruction of the jaw muscles.
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Left ventricular ejection fraction was measured by magnetic resonance imaging (MRI) and compared with standard monoplane left ventriculography in 46 patients with various cardiac diseases. Two different MRI strategies were used. In 28 patients (group 1), ejection fraction was determined using a single slice comparable with the right anterior oblique projection of the ventriculogram. Comparison of left ventricular ejection fraction yielded a poor correlation between single slice MRI (y) and ventriculography (x) (y = 28.7 + 0.47 x, r = 0.65). In 18 patients (group 2), a multiple contiguous slice MRI technique was used to allow ejection fraction and stroke volume determination by summing up the volumes of ventricular cavity intersections. Regression analysis showed a high correlation between multiple slice MRI (y) and ventriculography (x) (y = 7.2 + 0.88 x, r = 0.98). Also, correlation between MRI right (y) and left (x) ventricular stroke volumes was satisfactory, (y = -12.8 + 1.09 x, r = 0.83). It is concluded that the multiple slice imaging technique in MRI provides an accurate noninvasive means for quantification of left ventricular ejection fraction that can be extended to the determination of left ventricular volume.
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Among 100 patients with an infarction of the brain reported on MR and clinically confirmed there were 4 with widespread lesions of the temporal and occipital lobes, thalamus, midbrain, pons and cerebellum, all supplied by arteries originating around the top of the basilar artery. Clinically these patients presented the "top of the basilar" syndrome, which is caused by a disturbance in circulation at the top of the basilar artery. Which brain areas are involved may be deduced theoretically from the vascular anatomy. These lesions can, we believe, be clearly detected using MR, because of its sensitivity to ischaemic disturbances and in the posterior fossa. We report our 4 patients here to illustrate the clinical presentation and MR findings of the "top of the basilar" syndrome.
In 28 patients with various cardiac diseases we compared ejection fractions obtained by magnetic resonance imaging in a single oblique slice with monoplane ventriculography in the right anterior oblique projection, the latter serving as the standard. Also, results were evaluated for clinical relevance and relation to image quality. The correlation between the two techniques was moderate (r = 0.65). According to our standardized limits for clinical relevance, insufficiently correlating ejection fractions were obtained in 14 patients. In 8 of these patients this was attributed to poor endocardial edge detection. Edge detection problems were more frequently encountered by imaging with echo-time 20 msec than with echo-time 32 msec. Other causes for mismatching of the obtained ejection fractions are discussed. It is concluded that determination of ejection fraction by single slice magnetic resonance imaging should not be used for clinical application. Improvement can be expected by using a contiguous slicing technique, a longer echo-time in the spin-echo pulse sequence, or in due course by application of newly developed fast-imaging pulse sequences.
Anomalies of the corpus callosum (CC) in children can be subdivided into two main categories: Malformations (also known as dysgenesis) and damage to a previously well-formed callosum. Pre- or perinatally acquired damage may have a mainly vascular, obstructive or hypoxic-ischemic etiology, whereas endotoxins and exotoxins might also play a role. Early postnatally acquired CC damage in children is mostly of vascular or traumatic origin. In some instances the CC is thinned after chronic pressure (e.g. in hydrocephalics). Nineteen of fifty children with psychomotor retardation had CC anomalies, most of them suggestive of acquired damage. Mild forms of CC anomalies are visible with MRI, but might be missed with a CT-scan. Children with acquired CC anomalies have signs of supposed Interhemispheric Disconnection (ID), which is partly responsible for their clinical syndrome of mental and motor retardation. The likelihood of finding a CC anomaly in a child seems to be enhanced by the predictive use of neuropsychological tasks indicative for ID.
Forty-two patients with laryngeal carcinomas were examined with computed tomography (CT) and magnetic resonance (MR) imaging. The accuracy of both CT and MR imaging in the depiction of cartilage invasion was evaluated in 16 patients by comparing findings at CT and MR with pathologic findings. Calcified cartilage that has been invaded by cancer is frequently seen on CT scans as having an intact contour. Tumor approaching nonossified cartilage may simulate cartilage invasion. On T1-weighted MR images, invaded marrow of ossified cartilage is of intermediate signal intensity, allowing it to be differentiated from normal bone marrow. On proton-density images, tumor is of increased signal intensity, which allows it to be differentiated from nonossified cartilage. In our experience, the specificities of CT and MR imaging were approximately equal (91% and 88%, respectively), but CT had a considerably lower sensitivity than MR (46% vs. 89%). Gross movement artifacts, which resulted in nondiagnostic images, occurred in 16% of the MR examinations. MR imaging is recommended as the modality of choice in the diagnosis of cartilage invasion.
The use of Gd-DTPA in nondegenerative spinal lesions is described. Thirty consecutive patients were examined by MR with and without Gd-DTPA. The information obtained with unenhanced T1- and T2-weighted spin-echo images was compared with that obtained with Gd-DTPA T1-weighted images. The results showed that, according to the criteria used, more information was present on the MR images with Gd-DTPA in 18 of 30 patients. In six of 30 patients, the improved quality of the images led to a change in the neurosurgical or neurologic approach. Gd-DTPA proved to be a safe contrast medium; no side effects or adverse reactions were observed. It is recommended that Gd-DTPA be used in nondegenerative lesions involving the spinal cord to obtain the same or more information in a shorter acquisition time.
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This report concerns a clinical trial with Gd-DTPA as an intravenous contrast medium for MRI in patients with neurological disorders. 50 patients (30 female, 20 male) were examined without and with Gd-DTPA and the results of CT scanning and MR scanning without and with Gd-DTPA were compared. All patients tolerated the contrast medium very well. In the various patient groups, Gd-DTPA often added to the information. This was especially true in the tumor group, where better delineation of tumor, blood, and edema was obtained.
Diagnostic and therapeutic problems of Sneddon's syndrome are reviewed on the basis of the observation of a pregnant 36-year-old female. She had had Hodgkin's disease stage I, curatively treated when she was 23 years old. She developed cerebral ischemic events, initially ascribed to isolated cerebral angiitis, associated with progressive dermatological lesions (generalised livedo racemosa). A temporal artery biopsy did not reveal giant cell angiitis, while the cutaneous arterioles in a biopsy showed marked intimal proliferation without inflammatory cell infiltration. The literature on Sneddon's syndrome is reviewed.
A formal inquiry on the health state of 1206 legally adopted children from Indonesia revealed cerebral palsy in 9 (0.9% of 1029 responses obtained), including two who had died. CT examination performed in 7 cases was abnormal in all. Four types of lesions were seen: 1. Bilateral full thickness porencephalies (BFTP lesion) in 4 cases, amounting to 0.4% of the total population on which response was obtained. 2. Full thickness porencephaly of the area of one internal carotid artery in 1 case. 3. Schizencephaly-like lesion in 1 case, confirmed by magnetic resonance imaging. 4. Supratentorial midline cyst resulting in hydrocephalus. The frequency of the BFTP lesion found in 4 out of 7 cerebral palsied investigated by CT is remarkable in view of its rarity in radiological studies on cerebral palsy and because of its relationship to prenatal rather than perinatal damage according to previous pathological studies. This is the first systematic study on the neurodevelopmental outcome of a group of adopted babies which indicates an increased risk to specific prenatal brain damage.
Pathological criteria for diffuse gliomatosis are clearly demarcated but its clinical diagnosis has always been hampered by the imaging techniques used. Although with the advent of CT scanning clinical possibilities were improved, isodense brain lesions are difficult to detect and in these cases the diagnosis gliomatosis cerebri can only be suspected from the clinical signs and the absence of radiological signs. We have studied a young patient with a peculiar clinical history, in whom comparison of the CT-scan and NMR scan yielded remarkable results. Our clinical diagnosis of (diffuse) gliomatosis was confirmed by biopsy.