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Biomedical subjects

M H Smet

Publications and source records attributed to M H Smet.

At least 19 recordsLinked to original sources
PubMed2001

Three-dimensional computed tomography-based, personalized drill guide for posterior cervical stabilization at C1-C2.

STUDY DESIGN: Cadaver and preliminary clinical study. OBJECTIVES: To enhance the precision of screw positions for posterior transarticular fixations according to Magerl at C1-C2. SUMMARY OF BACKGROUND DATA: The vertebral arteries are at risk during the Magerl operation and may be damaged in up to 4.1% of cases. Even intraoperative navigation, as often used nowadays, does not provide optimal screw positioning in all patients. METHODS: According to the three-dimensional CT data obtained for every individual cadaver or patient, a template was designed for the posterior course of C2: the template contains a drill guide allowing navigated screw positioning inside the left and right isthmus of C2. For a first series of five cadavers a template with clamps connecting only to the lamina of C2, excluding the spinous process from the interface, was carried out. For a second series of three cadavers the template was connected not only to the lamina but also to the spinous process of C2. Both cadaver series were performed without any fluoroscopic control at surgery. Eventually the technology was applied in two clinical cases. RESULTS: The rotational stability of the template toward the lamina C2 was insufficient in the first series, but for the second series both the entry points and screw trajectories were very satisfactory. CONCLUSIONS: Although the actual experience is limited, the idea of using a template with drill guide might simplify and shorten the surgical act and at the same time enhance the accuracy of C1-C2 transarticular screw positioning.

Bone Screws↗
PubMed2000

Three-dimensional imaging of acetabular dysplasia: diagnostic value and impact on surgical type classification.

OBJECTIVE: To investigate the diagnostic value and the impact on surgical type classification of three-dimensional (3D) images for pre-surgical evaluation of dysplastic hips. MATERIALS AND METHODS: Three children with a different surgical type of hip dysplasia were investigated with helical computed tomography. For each patient, two-dimensional (2D) images, 3D, and a stereolithographic model of the dysplastic hip were generated. In two separate sessions, 40 medical observers independently analyzed the 2D images (session 1), the 2D and 3D images (session 2), and tried to identify the corresponding stereolithographic hip model. The influence of both image presentation (2D versus 3D images) and observer (degree of experience, radiologist versus orthopedic surgeon) were statistically analyzed. The SL model choice reflected the impact on surgical type classification. RESULTS: Image presentation was a significant factor whereas the individual observer was not. Three-dimensional images scored significantly better than 2D images (P=0.0003). Three-dimensional imaging increased the correct surgical type classification by 35%. CONCLUSION: Three-dimensional images significantly improve the pre-surgical diagnostic assessment and surgical type classification of dysplastic hips.

Acetabulum↗
PubMed1997

Bronchopulmonary dysplasia: correlation of radiographic and clinical findings.

BACKGROUND AND PURPOSE: Abnormalities of the chest wall have been described in bronchopulmonary dysplasia (BPD). Clinical, radiographic and pulmonary function variables were evaluated in 1-year-old children ventilated because of neonatal lung disease in order to quantify these thoracic changes and to evaluate the lung disease. METHODS: The pulmonary status of 51 infants with neonatal lung disease requiring artificial ventilation was reevaluated clinically and radiographically at the age of 1 year. Twenty-two of these infants had developed BPD. Thoracic depth and width were measured clinically and on chest X-ray. The Toce score evaluated the presence of cardiomegaly, hyperinflation, emphysema and interstitial lung disease. Lung function was measured after sedation using previously reported methods. In BPD patients, Toce score and lung function were determined and compared at 1 month and at 1 year of age. RESULTS: In BPD patients, chest depth was significantly smaller when measured clinically as well as on chest radiograph (P < 0.05; Mann-Whitney U-test). There was a statistically significant correlation between chest depth measured clinically and on chest X-ray. Toce score was significantly higher in BPD patients (P < 0.05). In BPD patients intersitial abnormalities and decreased lung compliance were more frequent at the age of 1 month than at the age of 1 year. At the age of 1 year, hyperinflation was more frequent and at that time increased airway resistance was still noted. Thus the type of X-ray abnormality reflects the type of lung function disturbance. CONCLUSION: The flatness of the chest is most likely a consequence of the long-standing lung function abnormalities.

Bronchopulmonary Dysplasia↗
PubMed1997

The Holt-Oram syndrome: radiological approach.

The clinical and radiological findings in a female child with Holt-Oram syndrome are reported. The most important features are cardiac anomalies associated with typical anomalies of the skeleton of the forearms.

Child, Preschool↗
PubMed1995

Submandibular gland mucocele of the extravasation type. Report of two cases.

The clinical and radiological differential diagnosis of cystic lesions of the head and neck region can be difficult. We report two cases of submandibular gland mucoceles presenting as cystic masses in the submandibular region. The imaging characteristics and differential diagnosis are discussed.

Adolescent↗
PubMed1995

A semiautomatic three-dimensional segmentation method for disarticulation of bone structures on spiral computed tomography images.

The use of binary thresholding for segmenting bone structures on spiral computed tomography images is negatively influenced by partial volume effects (PVEs) induced by the image acquisition. PVE leads to mixed voxels, making the binary decision "bone" or "nonbone" a difficult one to take. As a result, two distinct bone structures that are close to each other will often appear to be connected by this method. A typical example consists of "acetabulum/femural head" pairs in the pelvic region. To separate them, a clinical user must interactively draw a disarticulation line. This procedure is time consuming (often interaction in 50 slices is needed) and leads to unsmooth visualization of the disarticulated areas (by three-dimensional [3D] rendering techniques). We developed a semiautomatic cutting algorithm that leads to smooth disarticulated surfaces and considerably decreases the amount of user interaction. A sheet detection operator is applied to automatically separate bone structures. Detected sheets are used as disarticulation lines. Postprocessing ensures that sheets not relevant for the application do not influence the resulting image. Our approach is encapsulated in an interactive segmentation environment based on thresholding and 3D connected-component labeling. Results are shown for pelvic region, wrist, and foot bone disarticulations.

Algorithms↗
PubMed1995

[Clinical application of three-dimensional spiral CT in skeletal disorders].

Three-dimensional (3D) computed tomographic reformations are used as an adjunct to standard axial computed tomography (CT) in the evaluation of disorders affecting areas of complex anatomy such as the skull, the spine, the pelvis, hands and feet. 3D-CT can provide a clear impression of lesion extent, pattern, shape and proximity to adjacent structures. This unique spatial information potentially has a significant impact on decisions regarding resectability, surgical approach and repair. The basic requirements for high-quality 3D-reformations are an absence of patient movement and narrow-width transaxial sections. Spiral CT significantly contributes to fulfilling these requirements. In addition, spiral CT scan data can be used to produce the ultimate representation of the third dimension: a life-size palpable medical model. In this review we describe the process of three-dimensional reconstruction and highlight potential problems arising during 3D-imaging processing. Useful clinical applications of spiral CT for 3D-visualization of skeletal pathology are discussed.

Bone Diseases↗
PubMed1995

[Three-dimensional imaging of acetabular fractures using spiral CT].

Seven adult patients with acetabular fractures were investigated with conventional X-rays, axial spiral computed tomographic (CT) images and three-dimensional (3D) surface rendered reconstructions. Spiral CT has the advantage that it acquires the data much faster than incremental CT, resulting in less motion artefacts. A semi-automatic three-dimensional environment for segmentation has been developed in our institution. It created significant reduction of user interaction and improved visualization of acetabular and femoral joint surfaces. The main advantages of three-dimensional visualization of acetabular fractures included: creation of unlimited and unique views by which fracture location, fracture extension, fragment shape and fragment position became more clear, better visualization of acetabular dome and quadrilateral plate and more simple and easier interpretation of these complex fracture patterns. On the other hand, 3D surface reconstructions do not accurately demonstrate undisplaced fractures, intra-articular fragments may be obscured, congruence assessment is uneasy, and soft tissue injuries are not shown. Therefore, we consider 3D images of acetabular fractures as being complementary to and not a substitute to plain radiographs and axial CT scans.

Acetabulum↗
PubMed1994

Localized brain proton NMR spectroscopy in young adult phenylketonuria patients.

Localized proton magnetic resonance spectroscopy with short echo time (TE = 20 ms) was used to investigate biochemical changes in the cerebral white matter of 20 young adult patients (median 19 years) with phenylketonuria (PKU). Results were compared with those of a group of 12 age-matched healthy volunteers (median 25 years). Concentrations of N-acetyl-aspartate (NAA) and choline (Cho) relative to creatine (Cr) were unchanged. However, concentrations of inositol (Ins) relative to creatine were found to be significantly lower (P < 0.001) in the PKU patients (0.30 +/- 0.09 versus 0.57 +/- 0.17). Individual inositol concentrations did not correlate with age, diet, serum phenylalanine (Phe) levels or extent of pathological regions in the T2-weighted images. The lack of correlation with individual data suggests that the decreased inositol concentration could be related to a metabolic deficiency during fetal development. No signal from the phenyl ring protons of phenylalanine was detected in the PKU patients (phenylalanine serum concentration < or = 1.27 mM), which suggests that concentration of phenylalanine may be lower in brain than in serum.

Adolescent↗
PubMed1994

Late-onset Bochdalek hernia with a rare postoperative complication: case report.

We report a case of a 7-year-old-girl with a late-presenting Bochdalek hernia. The postoperative course was complicated by splenic torsion and subsequent total splenic infarction. Total splenic infarction due to splenic torsion has been reported in children with "wandering spleen" and in incarcerated Bochdalek hernias, but to our knowledge, not as a postoperative complication of Bochdalek hernia repair.

Child↗
PubMed1994

Eosinophilic granuloma of the head and neck: CT and MRI features in three cases.

We report the radiological findings and more specifically the MRI features in three typical cases of Langerhans' cell histiocytosis of the head and neck. All three cases were of solitary eosinophilic granuloma of bone: two mandibular and one temporal bone lesion. Reports on the MRI features of head and neck eosinophilic granulomas are rare.

Adolescent↗
PubMed1993

Sonographic demonstration of congenital adrenal hyperplasia in the neonate: the cerebriform pattern.

Sonographic examination of the adrenal glands of three newborns with congenital adrenal hyperplasia demonstrated a cerebriform pattern. This is introduced as a sonographic feature specific to the disease. This finding in patients with ambiguous genitalia should suggest the diagnosis even if the adrenals are not significantly enlarged, and should prompt appropriate biochemical analysis and treatment.

Adrenal Glands↗
PubMed1993

Xanthogranulomatous pyelonephritis in a child.

Xanthogranulomatous pyelonephritis is an uncommon form of chronic aggressive infection of the kidney and surrounding tissues usually affecting middle aged women. It is rarely seen in childhood. We report the case of a female child with a history of fatigue, progressive anorexia, and fever in whom a diagnosis of pyelonephritis on a predisposing factor of lithiasis was suggested. After initial antibiotic treatment, nephrectomy was needed for an acute general deterioration. Pathology demonstrated xanthogranulomatous pyelonephritis.

Child, Preschool↗
PubMed1992

Pictorial essay: right aortic arch.

Right aortic arch is a rare congenital anomaly. It can be either an isolated finding or it can be part of a double aortic arch. This article discusses the radiographic appearance of this congenital anomaly on conventional chest X-ray, angiography, CT, and MRI.

Aorta, Thoracic↗