Biomedical subjects
Publications and source records attributed to Thierry A G M Huisman.
We describe the prenatal MR findings in a 29-week fetus with a cloacal variant (urogenital sinus and anterior placed anus) in combination with an enlarged clitoris and urethral duplication and correlate them with postnatal imaging. Fetal MR imaging permits the diagnosis and characterization of cloacal and urogenital sinus malformations in utero. This information may guide pre-, peri- and postnatal management.
OBJECTIVE: This paper reports and discusses on the possible etiology of postoperative contralateral facial nerve palsy after uneventful evacuation of a subdural haematoma or hygroma after mild head trauma in two children with pre-existing middle cranial fossa subarachnoid cysts. RESULTS: Two 14- and 15-year-old boys had prolonged headaches after mild head injuries. CT showed a right-sided middle cranial fossa arachnoid cyst in each patient. In one patient, an ipsilateral subdural haematoma was identified, and in the other, bilateral hygromas were identified. Exacerbation of symptoms required emergency evacuation of the subdural haematoma in the first child, and bilateral external drainage of the hygroma in the other child. In both children the late postoperative period was complicated by peripheral facial nerve palsies contralateral to the arachnoid cyst. CONCLUSION: Facial nerve palsy may be a complication of hygroma or haematoma drainage. The etiology is not clear; traction of the facial nerve due to displacement of the brainstem may be the most likely explanation.
The objectives were to study the "impact" of the magnetic field strength on diffusion tensor imaging (DTI) metrics and also to determine whether magnetic-field-related differences in T2-relaxation times of brain tissue influence DTI measurements. DTI was performed on 12 healthy volunteers at 1.5 and 3.0 Tesla (within 2 h) using identical DTI scan parameters. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured at multiple gray and white matter locations. ADC and FA values were compared and analyzed for statistically significant differences. In addition, DTI measurements were performed at different echo times (TE) for both field strengths. ADC values for gray and white matter were statistically significantly lower at 3.0 Tesla compared with 1.5 Tesla (% change between -1.94% and -9.79%). FA values were statistically significantly higher at 3.0 Tesla compared with 1.5 Tesla (% change between +4.04 and 11.15%). ADC and FA values are not significantly different for TE=91 ms and TE=125 ms. Thus, ADC and FA values vary with the used field strength. Comparative clinical studies using ADC or FA values should consequently compare ADC or FA results with normative ADC or FA values that have been determined for the field strength used.
The computed tomography and MRI imaging findings in a case of pituitary duplication and epipharyngeal teratoma are described in a newborn baby girl with respiratory difficulties. Associated skull base and central nervous system malformations are presented. Teratoma diagnosis was confirmed by histology. The embryological pathogenesis is discussed.
Intracranial hemorrhage is one of the most common causes of acute focal neurologic deficit in children and adults. Neuroimaging including ultrasonography (US), computer tomography (CT) and magnetic resonance imaging (MRI) is essential in the diagnosis of intracranial hemorrhage. Imaging findings should guide treatment. The highly variable appearance of an intracranial hemorrhage can be challenging. A thorough knowledge of hematoma evolution and US, CT and MR hematoma characteristics is mandatory for adequate interpretation of findings. The purpose of this review is (1) to summarize the imaging characteristics of intracranial hemorrhage on various imaging techniques and (2) to review the various types of intracranial hemorrhage, and their causes.
Progressive multifocal leukoencephalopathy is a severe demyelinating disease of the central nervous system caused by a JC papovavirus infection. Prognosis is poor with fatal outcome within 1 year in 90% of patients. Our case report shows that diffusion tensor imaging can give early and specific information about disease status and extent in a 15-year-old girl with progressive multifocal leukoencephalopathy associated with congenital human immunodeficiency virus (HIV) infection.
PURPOSE: To determine whether diffusion-weighted magnetic resonance (MR) imaging findings and conventional MR imaging findings correlate with initial Glasgow Coma Scale score and score on modified Rankin scale at discharge. MATERIALS AND METHODS: Twenty-six patients (18 male and eight female patients; mean age, 25.2 years; age range, 4-72 years) with diffuse axonal injury were examined with diffusion-weighted MR imaging and with fluid-attenuated inversion recovery, T2-weighted fast spin-echo, and T2*-weighted gradient-echo sequences. All images were evaluated by two neuroradiologists in consensus. Tissue volume with trauma-related signal-intensity abnormality on images from each sequence, number of lesions for each sequence, number of lesions for all sequences, and number of lesions with reduced apparent diffusion coefficient were correlated with scores on Glasgow Coma Scale and modified Rankin scale. Involvement of brainstem, deep gray matter, and corpus callosum were also correlated with clinical scores. Spearman rank correlation coefficients (r) were calculated. RESULTS: The strongest correlation was between signal-intensity abnormality volume on diffusion-weighted images and modified Rankin score (r = 0.772, P <.001). The strength of this correlation did not improve when only volume of lesions with decreased apparent diffusion coefficient was considered. For lesion number, the strongest correlation was between lesion number on images acquired with all sequences and modified Rankin score (r = 0.662, P <.001). For lesion location, the strongest correlation was between lesion location in the corpus callosum and modified Rankin score (r = 0.513, P =.007). CONCLUSION: Volume of lesions on diffusion-weighted MR images provides the strongest correlation with a score of subacute on modified Rankin scale at discharge. Total lesion number also correlates well with modified Rankin score. In future, diffusion-weighted images may be useful in determining treatment strategies for acute head injury.
Infantile hepatic choriocarcinoma is a rare, highly malignant germ-cell tumour believed to result from a choriocarcinoma of the placenta that spreads to the child. Most infants present with a characteristic clinical picture of anaemia, hepatomegaly and precocious puberty. Imaging findings, including conventional MRI, may be non-specific. To improve the accuracy of diagnosis, we present the imaging findings of contrast-enhanced dynamic MRI in a 4.5-month-old boy with infantile hepatic choriocarcinoma.
The purpose of this study was to determine the effect of patient positioning on sonographic renal measurements and to test if the patient position alters the three-dimensional shape of the kidneys. The maximum longitudinal renal length and transverse renal width and depth were measured in the supine and prone position in 100 children (200 kidneys). Age ranged from 6 months to 16 years (mean age 5 years). The results were compared for statistically significant differences. The maximum measured longitudinal renal length was statistically significantly larger in the supine than in the prone position (supine position, left: 8.0 cm; right: 7.7 cm; prone position, left: 7.9 cm, right: 7.6 cm; P<0.001). There was no statistically significant change in the transverse diameters (width and depth, P>0.001) and renal volume ( P>0.001) in the supine vs. prone positions. Our results show that position-induced reshaping of the kidneys is unlikely to be responsible for the discrepancy in maximum longitudinal renal measurements comparing supine with prone positions. Position-dependent changes in the degree of filling of the renal calyces and pelvis as well as errors in caliper distance measurements for the different scan depths (supine vs. prone) are more likely to be responsible for the encountered differences. Consequently, we recommend to add prone renal length measurements in addition to the supine measurements. In follow-up examinations, renal length measurements should only be compared that have been collected in the same patient position.
OBJECTIVE: To investigate the effect of ADC heterogeneity on region of interest (ROI) measurement of isotropic and anisotropic water diffusion in acute (< 12 h) cerebral infarctions. METHODS AND MATERIALS: Full diffusion tensor images were retrospectively analyzed in 32 patients with acute cerebral infarction. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were measured in ischemic lesions and in the corresponding contralateral, normal appearing brain by using four ROIs for each patient. The 2 x 2 pixel square ROIs were placed in the center, the lateral rim and the medial rim of the infarction. In addition, the whole volume of the infarction was measured using a free hand method. Each ROI value obtained from the ischemic lesion was normalized using contralateral normal ROI values. RESULTS: The localization of the ROIs in relation to the ischemic lesion significantly affected ADC measurement (P < 0.01, using Friedman test), but not FA measurement (P = 0.25). Significant differences were found between ADC values of the center of the infarction versus whole volume (P < 0.01), and medial rim versus whole volume of infarction (P < 0.001) with variation of relative ADC values up to 11%. The differences of absolute ADC for these groups were 22 and 23%, respectively. The lowest ADC was found in the center, followed by medial rim, lateral rim and whole volume of infarction. CONCLUSION: ADC quantification may provide variable results depending on ROI method. The ADC and FA values, obtained from the center of infarction tend to be lower compared to the periphery. The researchers who try to compare studies or work on ischemic quantification should be aware of these differences and effects.
Magnetic resonance imaging (MRI) represents a non-invasive alternative to full autopsy in neonatal death if parents refuse classical full autopsy. MRI offers high resolution images of the entire neonate without disrupting the integrity of the child. Neonatal malformations or pathologies that are responsible for the death of the neonate can be identified. A major disadvantage of MR-autopsy is the lack of tissue sampling. Chromosomal, histological or microbiological analyses are consequently missing. MR-autopsy has proven to be especially helpful in the evaluation of the central nervous system but is limited in complex cardiac malformations. The limitations and possibilities of MR-autopsy are discussed.
BACKGROUND AND PURPOSE: Multiple biomarkers are used to quantify the severity of traumatic brain injury (TBI) and to predict outcome. Few are satisfactory. CT and conventional MR imaging underestimate injury and correlate poorly with outcome. New MR imaging techniques, including diffusion tensor imaging (DTI), can provide information about brain ultrastructure by quantifying isotropic and anisotropic water diffusion. Our objective was to determine if changes in anisotropic diffusion in TBI correlate with acute Glasgow coma scale (GCS) and/or Rankin scores at discharge. METHODS: Twenty patients (15 male, five Female; mean age, 31 years) were evaluated. Apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) values were measured at multiple locations and correlated with clinical scores. Results were compared with those of 15 healthy control subjects. RESULTS: ADC values were significantly reduced within the splenium (Delta18%, P =.001). FA values were significantly reduced in the internal capsule (Delta14%; P <.001) and splenium (Delta16%; P =.002). FA values were significantly correlated with GCS (r = 0.65-0.74; P <.001) and Rankin (r = 0.68-0.71; P <.001) scores for the internal capsule and splenium. The correlation between FA and clinical markers was better than for the corresponding ADC values. No correlation was found between ADC of the internal capsule and GCS/Rankin scores. CONCLUSION: DTI reveals changes in the white matter that are correlated with both acute GCS and Rankin scores at discharge. DTI may be a valuable biomarker for the severity of tissue injury and a predictor for outcome.
BACKGROUND AND PURPOSE: We hypothesized that, in acute cerebral ischemic stroke, anisotropic diffusion increases if T2 signal intensity is not substantially elevated and decreases once T2 hyperintensity becomes apparent. Our purpose was to correlate fractional anisotropy (FA) measurements with the clinical time of stroke onset, apparent diffusion coefficients (ADC), and T2 signal intensity. METHODS: Tensor diffusion-weighted images (DWIs) of 25 patients were obtained within 12 hours of symptom onset. Trace DWIs, ADCs, FAs, and echo-planar T2-weighted images (T2WI) were generated. Stroke and contralateral normal volumes of interest (VOIs) were outlined on DWIs and projected onto the inherently coregistered ADC map, FA map, and echo-planar T2WI. Mean signal intensity of the ischemic and contralateral normal VOIs were compared for relatives change in ADC, FA, and signal intensity on T2WIs. RESULTS: A significant negative correlation was observed between FA and T2 signal-intensity change (r = -0.61, P =.00009). A trend of correlation between FA signal intensity and time of onset were found (r = -0.438, P =.025). No significant correlation was found between ADC and FA values (r = -0.302, P =.134). The mean ADC reduction in the ipsilateral ischemic volume was 31% +/- 11 compared with the contralateral normal side. CONCLUSION: Change in FA is inversely correlated with T2 signal intensity and, to a lesser extent, the time of onset, but it is not well correlated with ADC values in the acute stage.
Developmental nasal midline masses in children are rare lesions. Neuroimaging is essential to characterise these lesions, to determine the exact location of the lesion and most importantly to exclude a possible intracranial extension or connection. Our objective was to evaluate CT and MRI in the diagnosis of developmental nasal midline masses. Eleven patients (mean age 4.5 years) with nasal midline masses were examined by CT and MRI. Neuroimaging was evaluated for (a) lesion location/size, (b) indirect (bifid or deformed crista galli, widened foramen caecum, defect of the cribriform plate) and direct (identification of intracranially located lesion components or signal alterations) imaging signs of intracranial extension, (c) secondary complications and (d) associated malformations. Surgical and histological findings served as gold standard. Nasal dermoid sinus cysts were diagnosed in 9 patients. One patient was diagnosed with an meningocele and another patient with a nasal glioma. Indirect CT and MRI signs correlated with the surgical results in 10 of 11 patients. Direct CT findings correlated with surgery in all patients, whereas the direct MRI signs correlated in 9 of 11 patients. In 2 patients MRI showed an intracranial signal alteration not seen on CT. Neuroimaging corrected the clinical diagnosis in 1 patient. One child presented with a meningitis. In none of the patients was an associated malformation diagnosed. Intracranial extension is equally well detected by CT and MRI using indirect imaging signs. Evaluating the direct imaging signs, MRI suspected intracranial components in 2 patients without a correlate on CT. This could represent an isolated intracranial component that got undetected on CT and surgery. In 9 patients CT and MRI matched the surgical findings. The MRI did not show any false-negative results. These results in combination with the multiplanar MRI capabilities, the different image contrasts that can be generated by MRI and the lack of radiation favour the use of MRI as primary imaging tool in these young patients in which the region of imaging is usually centred on the radiosensitive eye lenses.
We report a 12-year-old boy who presented with incomplete right ophthalmoplegia, exophthalmos and headache. Initial CT and MRI revealed a mass in the right cavernous sinus. During tumour work-up, CT identified additional tumour within the mediastinum. Biopsy of the mediastinal lesion identified Burkitt's lymphoma. We report on this case because radiologists and clinicians should be alerted to identify sites of primary Burkitt's lymphoma outside of the central nervous system if clinical symptoms indicate, or imaging shows, CNS lesions. Primary CNS involvement in Burkitt's lymphoma is rare.
Perfusion-weighted magnetic resonance imaging (PWI) has been proposed as an attractive non-invasive tool for evaluating cerebral haemodynamics. Quantitative maps of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and various other haemodynamic parameters can be obtained. Recent advances in hard- and software made PWI available for clinical routine. Although PWI became common in adult neuroradiology, it remains challenging in pediatric neuroradiology. In this article, the different PWI techniques that render haemodynamic maps of the brain are presented and discussed. The normal developmental changes of the cerebral haemodynamics in children as measured by PWI are presented as well as the application of PWI in cerebral ischaemia, primary and secondary cerebral vasculopathies and in cerebral tumours.
Diffusion-weighted imaging (DWI) of the brain represents a new imaging technique that extends imaging from depiction of neuroanatomy to the level of function and physiology. DWI measures a fundamentally different physiological parameter compared with conventional MRI. Image contrast is related to differences in the diffusion rate of water molecules rather than to changes in total tissue water. DWI can reveal pathology in cases where conventional MRI remains unremarkable. DWI has proven to be highly sensitive in the early detection of acute cerebral ischemia and seems promising in the evaluation of traumatic brain injury. DWI can differentiate between lesions with decreased and increased diffusion. In addition, full-tensor DWI can evaluate the microscopic architecture of the brain, in particular white matter tracts, by measuring the degree and spatial distribution of anisotropic diffusion within the brain. This article reviews the basic concepts of DWI and its application in cerebral ischemia and traumatic brain injury.
The past two decades have brought an enormous widening of interest in and knowledge about swallowing disorders. The most frequently used technique for swallow evaluation is X-ray videofluoroscopy. Most interventions are based on this examination. Only a few studies assessing interobserver reliability of videofluoroscopy have been published. The aim of our study was to assess the interobserver reliability of videofluoroscopy for swallow evaluation. Fifty-one consecutive dysphagic patients referred for videofluoroscopy were entered into the study regardless of their underlying disorder. The first swallow (5 ml of a semisolid radio-opague contrast media) of each patient was assessed in the lateral projection by 9 independent, experienced observers from different international swallow centers. All studies were evaluated according to a standardized protocol sheet and the interobserver reliability was calculated. The interobserver reliabilities assessed as kappa coefficient for parameters of the oral and pharyngeal phase, for the temporal occurrence of penetration/aspiration, and for the location of bolus residue ranged from 0.01 to 0.56. High reliability with an intraclass coefficient of 0.80 was achieved only with the well defined penetration/aspiration score. Our study underlines the need for exact definitions of the parameters assessed by videofluoroscopy, in order to raise interobserver reliability. To date, only aspiration is evaluated with high reliability by videofluoroscopy, whereas the reliability of all other parameters of oropharyngeal swallow is poor.