Biomedical subjects
Publications and source records attributed to T D Witkamp.
Osteochondroma of the mandibular condyle is extremely rare and may cause signs and symptoms like those seen in patients with temporomandibular joint dysfunction. Differentiation between osteochondroma and condylar hyperplasia is not possible on histologic grounds alone, but the radiographic and intraoperative findings together are usually sufficient to establish a definite diagnosis.
To study cerebral metabolism in neonates after unilateral cerebral infarcts 4 neonates (3 full-terms, one preterm with a gestational age of 35 weeks) with unilateral cerebral infarcts were examined at 7 to 49 days of postnatal age, using proton magnetic resonance spectroscopic imaging (1H-MRSI). Three neonates had infarcts of the left middle cerebral artery (MCA), one had a right posterior cerebral artery infarct and a more localized anterior lesion. Examinations were repeated in the three fullterm infants aged 2-3 months. Lactate resonances, which are not present in normal brain after term age, were demonstrated in two patients tested at 7 and 10 days of age respectively, and in one of them lactate was still present at two months. In all four neonates a decrease of the N-acetylaspartate/choline (NAA/Cho) ratio was seen within the area of infarction. Repeated MRS of two infants at three months showed an increase in NAA/Cho ratios in all brain areas, but values remained below normal in the infarcts. In the third infant a further decrease in the NAA/Cho ratio was demonstrated in the area of infarction at two months. The NAA/Cho ratios in the surrounding and contralateral brain tissue were normal in all infants. All three infants with a MCA infarct developed a hemiplegia. The aforementioned metabolic alterations in neonates with cerebral infarcts, demonstrated using 1H-MRSI, were found to be confined to the area of infarction and abnormalities persisted beyond the neonatal period.
The value of radiography, ultrasound and magnetic resonance imaging (MRI) in detecting skeletal and intraspinal pathology was assessed in infants with anorectal malformations, and the need for spinal MRI examination in this group of patients was evaluated. Twenty-one infants were examined with radiography, ultrasound and MRI of the lower spine. The detection of skeletal and intraspinal abnormalities was compared for the three imaging modalities. Fifteen patients were normal in all three examinations. Radiography showed bony skeletal abnormalities in six children, although sometimes very subtle. By ultrasound both bony and cartilaginous malformations were detected in all six patients and by MRI in five patients. Five of the six children with skeletal abnormalities had intraspinal pathology, detected in all cases by ultrasound and MRI. However, the abnormalities were more clearly demonstrated by MRI than by ultrasound. Spinal radiographs must be examined carefully for abnormalities, because they can indicate the presence or absence of intraspinal pathology. Normal radiographic and sonographic appearance of spinal anatomy in children with anorectal malformation makes MRI superfluous, but if radiographs or ultrasound are abnormal, MRI should be used to accurately depict possible intraspinal pathology.
A 20-yr-old man with progressive, painful diffuse swelling of his right shoulder muscles is reported. The diagnosis was muscle hypertrophy secondary to a congenital arterio-venous malformation (CAVM). Since a CAVM is not infrequently asymptomatic until the age of 20 to 30 yr and develops insidiously, the diagnosis may be delayed. In our patient, MRI rather than ultrasound and CT, led to the final diagnosis.
The purpose of this study was to test the hypothesis that a high lactate signal and a low N-acetyl-aspartate/choline ratio in neonates with postasphyxial encephalopathy indicated a high chance of an adverse outcome in vivo when proton magnetic resonance spectroscopy was used. Twenty-one full-term asphyxiated neonates were examined at a mean postnatal age of 7.1 d. Five patients died, and five survivors had handicaps. Eleven of the 16 survivors (seven without handicaps and four with handicaps) had a second examination at 3 mo of age. After magnetic resonance imaging, spectra were obtained at 1.5 tesla. A 20-mm-thick slice was selected through the basal ganglia. After optimizing the B-0 field, we used a double spin-echo pulse sequence (90-180-180 degrees) with a time to repeat of 2000 ms and a time to echo of 272 ms. Two-dimensional spectroscopic imaging was performed by 32 x 32 phase encoding steps in two directions in a 225-mm field of view, resulting in 1-mL volumes, followed by computerized processing. Neuromotor development was examined at 6 wk, 3 mo, and every 3 mo thereafter. Lactate resonances were seen only in the five patients with grade 3 postasphyxial encephalopathy. Lactate was distributed diffusely (n = 4), or localized in areas of infarction (n = 1). N-acetyl-aspartate/choline ratios were significantly lower in the patients with an adverse outcome than in the survivors without handicaps, both neonatally (p < 0.005, Wilcoxon's rank sum test) and at 3 mo (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Two temporomandibular joints from one specimen were investigated using magnetic resonance imaging and cryosectioning. Magnetic resonance images, photography of the tissue block surface, and on-tape histologic sections were compared. The left joint was imaged and sectioned in a coronal plane, and the right joint in an angulated coronal plane parallel to the long axis of the condyle. The temporomandibular joint disc could be seen in coronal and angulated coronal scans. The posterior band was imaged in angulated coronal magnetic resonance scans throughout the temporomandibular joint both medically and laterally. In coronal scans only parts of the disc proper could be seen, depending on the level of imaging or sectioning. The densely plaited fibrous tissue of the intra-articular tissues could be seen in magnetic resonance imaging, primarily anterior to the condyle; this tissue corresponded to the low signal intensity in magnetic resonance imaging. Medical and lateral disc attachments as well as the temporomandibular joint capsule were imaged in some of the magnetic resonance scans in both the coronal and the angulated coronal scans. In diagnosing anteromedial, medial, and lateral disc displacements, angulated coronal temporomandibular joint scanning is preferred over coronal scanning.
Two temporomandibular joints originating from one specimen were investigated using magnetic resonance imaging and cryosectioning. Magnetic resonance images, photographs of the surface of the tissue block, and on-tape sections were compared. The left joint was imaged and sectioned in a sagittal plane, the right joint in a plane perpendicular to the long axis of the condyle. The densely plaited fibrous tissue of the disc proper correlated extremely well with the low signal intensity in magnetic resonance imaging. The transition between the densely plaited fibrous tissue and the looser tissue of the posterior attachment was located anterior to the thickest part of the intra-articular tissues in most sections of the specimen. The temporomandibular joint disc could be seen in angulated as well as in sagittal magnetic resonance scans. The posterior band was imaged best in angulated magnetic resonance scans throughout the temporomandibular joint.
PURPOSE: To determine the frequency of appearance of various MR signs in mesial temporal sclerosis, to determine the optimal scanning planes for their visualization, and to propose a histologic explanation for the diminished demarcation between gray and white matter in the temporal lobe, a frequent MR finding in patients with mesial temporal sclerosis. METHODS: MR scans of 14 surgically treated patients with epilepsy and histologically proven mesial temporal sclerosis were assessed for the presence of six features: feature 1, high signal intensity in the hippocampus; 2, reduced hippocampal size; 3, ipsilateral atrophy of the hippocampal collateral white matter; 4, enlarged temporal horn; 5, reduced gray-white matter demarcation in the temporal lobe; and 6, decreased temporal lobe size. RESULTS: Feature 1 was present in 14 patients and was best appreciated on the T2-weighted images in planes parallel to the long axes of the hippocampi. Feature 2, present in 12 patients, and feature 6, present in 9 patients, were optimally seen in the coronal planes and on the inversion-recovery sequences in particular. Feature 3, present in 12 patients, was optimally seen on the coronal T2-weighted images. Feature 4, seen in 11 patients, was equally well seen in all planes (transverse, coronal, and parallel to the long axes of the hippocampi). Feature 5, seen in 10 patients, was best appreciated on the T2-weighted images in the planes of the long axes of the hippocampi. Histologic investigation of the temporal lobe white matter in the 10 patients with feature 5 demonstrated on the MR scan showed abnormalities in 7 cases. Oligodendroglia cell clusters were found in 6, with concomitant corpora amylacea in 1 case and perivascular macrophages with pigment a sole finding in another case. CONCLUSION: Of the six features found in cases of mesial temporal sclerosis on MR, increased hippocampal signal intensity is the most consistent. A decreased gray-white matter demarcation in the temporal lobe parenchyma is also a frequent feature of this disease. A combination of multiple scanning planes results in an optimal demonstration of lesions.
PURPOSE: To determine whether the lumbosacral junction of the vertebral column can be identified with sonography in newborns and infants and thus serve as a method for counting the lumbar and sacral vertebral bodies. METHODS: In 32 newborns and infants, the number of ossified vertebral bodies distal to the lumbosacral junction was counted with sonography and radiography. RESULTS: Sonographic and radiographic findings agreed in 29 of 32 examinations (91%). CONCLUSIONS: The lordotic transition at the lumbosacral junction can be identified with sonography in the majority of newborns and infants, allowing intraspinal structures to be related to a specific vertebral level.
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Marfan's syndrome is a connective tissue disorder, which mainly affects the cardiovascular system, together with ocular, skeletal and connective tissue. The cardiovascular manifestations in particular determine the mortality of this disorder. We studied 13 patients, suffering of Marfan's syndrome, with suspected aortic dilatation by means of magnetic resonance imaging (MRI). Aneurysmal dilatation of the aortic root and dissection were the two major findings in our study. Two of the five patients with dissections presented without relevant symptoms in the medical history nor at the time of the MRI examination.
A 36-year-old Caucasian woman presenting with persisting painful calves after a flu-like illness was diagnosed as having polyarteritis nodosa. Magnetic resonance imaging of the lower legs showed abnormal signal intensity of the outer muscle groups with sparing of the central located muscles. The good clinical response to oral prednisone was supported by improvement of MRI.
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In this paper the effects of reducing the flip angle of the 90-degree observation pulse in inversion recovery imaging are described and analyzed. When incorporated in an IR sequence with a short inversion time (STIR), reduction to the 90-degree pulse allows a significant shortening of the repetition time without loss in contrast, although at the expense of some signal/noise. The generalized STIR sequence thus combines the previously reported advantages of a conventional STIR sequence--suppression of ghost artifacts from abdominal wall movement, suppression of chemical shift and boundary artifacts, additive effects of N(H), T1 and T2 on image contrast--with reduced power deposition and the advantages resulting from shorter repetition times, viz, single heart-beat triggering, increased number of signal averages for suppression of motion artifacts, acquisition of interleaved contiguous slices without cross-talk or considerable time savings when the number of required slices is limited. The proposed method is demonstrated and experimentally verified by imaging experiments on phantoms and human subjects. In principle the method is applicable to all cases where STIR imaging has been proven to be successful.
Two patients with retroperitoneal cystic lymphangioma are reported with a review of the medical literature. In one, the patient was asymptomatic from the lesion but had a computed tomography (CT) and an ultrasound to evaluate the extent of disease with a known carcinoma of the colon. The second patient presented with an acute abdominal pain requiring surgical management. CT on this patient showed multiple cystlike cavities filled with fluid, in a retroperitoneal location. The preoperative diagnosis of retroperitoneal cystic lymphangioma was confirmed at surgery. Magnetic resonance (MR) performed on the second patient gave better delineation of craniocaudal extent and showed one of the cysts to have probable hemorrhage.
In craniomandibular disorders the diagnosis of internal derangements plays an important role. Findings from the history and the examination of active movements mostly lead to a working diagnosis. Additional orthopedic tests and radiological examination (e.g. arthrography) give more precise information. MRI (Magnetic Resonance Imaging) is a new technique with which the temporomandibular soft tissues can be imaged in a non-invasive way without the use of radiation. The position and configuration of the disc can be visualized both in the intercuspidal position and with various degrees of mouth opening.
The Magnetic Resonance (MR) appearance of adrenal hemorrhage in a neonate is described and compared with Ultrasound (US). The value of US studies in adrenal neonatal hemorrhage is well known. We present the MR appearance of this common condition.
Using cardiac-gated fast acquisition with multiple excitation (FAME), time curves of the cerebral aqueduct signals were derived in 19 healthy volunteers and 14 patients. A mean curve of the normal subjects was determined during systole. A relatively stable point of time was found at 270 msec after the R-wave supposed to be the reversal of the flow of cerebral-spinal fluid in the aqueduct. Different curves were noticed in complete aqueductal obstruction (n = 2); in other pathologic states, such as cerebral tumor (n = 3), normal pressure hydrocephalus (n = 3), and brain atrophy (n = 1), no different signal time curves were observed. Parameters such as aqueduct diameter, cerebro-spinal fluid volume and brain compliance are probably other important factors in aqueduct liquor flow.