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S G Wetzel

Publications and source records attributed to S G Wetzel.

17 recordsLinked to original sources
PubMed2005

Diffusion weighted imaging, apparent diffusion coefficient maps and stroke etiology.

OBJECTIVE: In acute ischemic stroke, the number and distribution of lesions on diffusion weighted imaging (DWI) have been shown to give clues to the underlying pathogenetic mechanisms. The objective of this study was to determine whether lesion features on DWI differ between stroke due to large artery atherosclerosis (LAA) and cardioembolism (CE), and to assess the role of apparent diffusion coefficient maps (ADC). METHODS: We retrospectively studied 83 consecutive patients with stroke caused by either LAA (n=40) or cardioembolism (n=43). DWI lesions were characterized by number, size, distribution (i. e. lesion pattern) and signal intensity on ADC maps. In part A, all hyperintense DWI lesions regardless of their ADC were compared. In part B, only hyperintense DWI lesions with hypointense appearance on ADC maps (i. e. acute lesions) were assessed. RESULTS: Part A: The frequency of multiple hyperintense DWI lesions (LAA: 28/40, CE: 21/43; p< 0.05) and the lesion number (LAA 4.7+/- 4.9; CE: 3.1+/- 4.7; p=0.01) were higher in LAA-patients. Involvement of >1 circulation (i. e. anterior plus posterior or bilateral anterior circulations) was present in 5 LAA-patients (13 %) and 4 CE-patients (9 %). Lesion size did not differ between LAA-stroke (35.1+/- 33.7 mm) and CE-stroke (35.4+/- 27.8 mm). Part B: Multiple hyperintense DWI lesions with low ADC occurred in 23/40 LAA-patients and in 15/43 CE-patients (p<0.05). Lesions in >1 circulation occurred only in CE-stroke (n=3; 7%) and never in LAA-stroke. CONCLUSIONS: (1) Multiple ischemic lesions occur significantly more often in LAA-stroke than in CE-stroke. (2) ADC maps are important in the comparison of DWI lesion patterns; DWI lesions in >1 circulation can only be assigned to a cardioembolic etiology if they appear hypointense on ADC maps.

Aged↗
PubMed2004

Double-lumen balloon microcatheter-assisted occlusion of cerebral vessels with coils: a technical note.

The purpose of this study was to describe a balloon-assisted double-lumen microcatheter technique to perform a controlled and tight coil packing of a vascular segment for vessel occlusion. This technique can be performed immediately after a test occlusion with the balloon kept in place and was, as illustrated in six cases, in our experience safe, straight forward to use and fast.

Adult↗
PubMed2004

The clinical significance of diffusion-weighted MR imaging in infratentorial strokes.

OBJECTIVE: To study the association between diffusion-weighted imaging (DWI) characteristics and stroke etiology, stroke severity, and functional outcome in patients with infratentorial strokes. METHODS: The authors prospectively studied 22 consecutive patients with acute infratentorial strokes. They used a blinded comparison of DWI features (number, distribution, and volume of lesions) with clinical characteristics, namely, stroke etiology (Trial of ORG 10172 in Acute Stroke Treatment [TOAST] classification), severity (NIH Stroke Scale [NIHSS]), length of stay (LOS), and functional 3-month outcome using modified Rankin Scale, Barthel Index, and a dichotomized outcome status (living at home vs institutionalization or death). RESULTS: Acute infratentorial DWI lesions were detected in 95% (21/22) of the patients. The number (p = 0.01) and the distribution (p < 0.001) of DWI lesions were correlated with stroke etiology. Patients with cardioembolic strokes (n = 5) had more DWI lesions (8.0 +/- 6.0) than those with other stroke etiologies (n = 17; 1.3 +/- 0.9; p < 0.001). Their lesion distribution differed from that of patients with noncardioembolic strokes (p < 0.001). Clinically silent, acute DWI lesions in the anterior circulation in addition to their infratentorial lesions were visualized in 3 of 5 patients with cardioembolic stroke and in none of 17 patients without sources of cardioembolism (p < 0.001). Pure infratentorial lesions were present in 15 of 17 patients with noncardioembolic strokes and in none of 5 cardioembolic stroke patients (p < 0.001). DWI lesion volume was not correlated with NIHSS score, LOS, outcome scores, or outcome status. CONCLUSION: In infratentorial strokes, multiple DWI lesions and a distribution of subsidiary, clinically silent DWI lesions in the anterior circulation suggest a cardioembolic stroke etiology. However, DWI lesion volume did not correlate with the NIHSS score and was no predictor of outcome.

Adult↗
PubMed2004

Radiation dose in vertebroplasty.

We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements.

Aged↗
PubMed2004

Diffusion-weighted MRI in cortical ischaemia.

We carried out MRI on 16 male and three female comatose patients, aged 2 days to 79 years, with suspected cortical ischaemia referred from our intensive care units. Using a head coil, and following standard imaging, including coronal fluid-attenuated inversion-recovery images, we performed diffusion-weighted imaging (DWI) using a whole-brain multislice single-shot echo-planar sequence with b 0 and 1000 s/mm2: 5-mm slices covering the whole brain, TR 7000 TE 106 ms, 128 x 128 pixels, field of view 250 mm, one excitation. Maps of apparent diffusion coefficients (ADC) were generated automatically. DWI showed cortical, basal ganglia and watershed-area high signal in all cases, associated with a decrease in ADC to 60- 80% of normal. DWI showed lesions not seen (40%) or underestimated (40%) on conventional T2-weighted imaging. Within 24 h of the onset of symptoms, DWI showed changes not readily detectable on T2-weighted images. The cortical high signal on DWI and the ADC changes, suggesting severe ischaemia rather than oedema, was found in areas known to be affected by cortical laminar necrosis. Extension to the brain stem and white matter was associated with a higher likelihood of death.

Adolescent↗
PubMed2001

Swallowing abnormalities in multiple sclerosis: correlation between videofluoroscopy and subjective symptoms.

The purpose of this study was to evaluate if subjective symptoms indicating an impaired deglutition correlate with videofluoroscopic findings in patients with multiple sclerosis (MS). Videofluoroscopic examinations of 18 MS patients were analyzed by a radiologist and a logopedist and compared with the symptoms of these patients. Four patients complained about permanent dysphagia. Six patients reported mild and intermittent difficulties in swallowing, but were asymptomatic at the time of videofluoroscopy. Eight patients had no symptoms regarding their deglutition. All patients ( n=4) who complained of permanent dysphagia showed aspiration. All patients ( n=6) with mild and intermittent difficulties in swallowing showed undercoating of the epiglottis and/or laryngeal penetration. Of those 8 patients without any swallowing symptoms, only 2 had a normal videofluoroscopy. Swallowing abnormalities seem to be much more frequent in patients with MS than generally believed and they may easily be missed clinically as long as the patients do not aspirate.

Adult↗
PubMed2001

Preliminary experience with dynamic MR projection angiography in the evaluation of cervicocranial steno-occlusive disease.

The application of a contrast-enhanced, two-dimensional MR technique, which provides dynamic projection angiograms at a subsecond temporal frame rate for depiction of the cervical and intracranial arteries, was evaluated in three healthy volunteers and seven patients with various cervicocranial steno-occlusive diseases. Intra-arterial digital subtraction angiography (DSA) served as standard of reference for findings in the patients. Magnetic resonance projection angiography (MRPA) was performed on a standard 1.5-T clinical MR imaging system at intravenous injection of a single dose of contrast agent (0.1 mmol/kg GdDTPA-BMA). Sixty consecutive images of the cerebral circulation were acquired at a temporal frame rate of 900 ms per image in the coronal plane. The collateral flow and the perfusion of the compromised vessel territory were readily assessed by MPRA in patients with occlusion of the internal cerebral artery (ICA) or middle cerebral artery (MCA). The leptomeningeal collateralisation of these patients was displayed in a dynamic fashion. Furthermore, quantitative perfusion measurement provided a difference between both MCA territories in the time to peak (deltaDTTP) of the contrast bolus of 1.12 +/- 0.28 s in five patients with severe stenosis or occlusion of the ICA (healthy volunteers 0.19 +/- 0.05 s). However, important pathological findings, such as the evaluation of carotid artery stenoses and the intracranial collateral flow pattern in patients with severe carotid stenoses, were not sufficiently assessable as compared with DSA. We conclude that the possibility of obtaining simultaneously information about morphology and perfusion dynamics of the cervicocranial vessels is unique in MPRA as compared with other MR techniques. However, in the applied form, the technique is not a reliable tool for the complete evaluation of the cervicocranial vessels in patients with steno-occlusive disease.

Adult↗
PubMed2001

Real-time interactive duplex MR measurements: application in neurovascular imaging.

OBJECTIVE: Real-time interactive duplex MR imaging is a new phase-contrast MR imaging technique that enables the quantification and display of flow velocities in real time without the need for cardiac gating. We investigated the feasibility and reliability of the technique to assess hemodynamic information both in vitro and in vivo in the carotid arteries and in the venous sinuses. SUBJECTS AND METHODS: Real-time interactive duplex MR measurements (TR/TE, 53/27; flip angle, 90 degrees; encoding velocity, 100 or 150 cm/sec) were performed in vitro with a steady-flow phantom and in 10 healthy volunteers in whom common and internal carotid artery velocities were measured. In eight volunteers, velocity measurements were also performed in the superior sagittal sinus during both normal breathing and hyperventilation. Time-velocity plots were analyzed qualitatively and quantitatively and compared with findings from conventional segmented k-space phase-contrast MR imaging and Doppler sonography. RESULTS: Velocity determinations for real-time duplex MR and conventional phase-contrast MR imaging showed an in vitro correlation of 0.99 and an in vivo correlation of 0.83 (carotid arteries) and 0.76 (venous sinus). Velocity measurements in the carotid arteries with real-time MR imaging were significantly lower than those obtained with conventional phase-contrast MR (averaged, 7.8%; p = 0.003) or sonography (23.7%, p < 0.001), likely because of volume averaging. Small but significant velocity changes occurring in the venous sinus during hyperventilation were reliably identified with both MR techniques. CONCLUSION: Real-time interactive duplex MR imaging can be effectively applied in neurovascular imaging to obtain hemodynamic information.

Adult↗
PubMed2000

Quantification of blood flow in the middle cerebral artery with phase-contrast MR imaging.

The aim of this study was to assess blood flow in the middle cerebral artery (MCA) according to age, gender, and side. Eighty-eight subjects without carotid obstruction were measured for mean velocity, vessel area, and volume flow rates of both MCA with phase-contrast MR. A high-resolution sequence with a matrix of 300 x 512 and a double oblique localizing strategy was used for measurement. A mean velocity of 33 +/- 6.8 cm/s, a mean vessel area of 6.2 +/- 1.2 mm2 and a mean flow rate of 121 +/- 28 ml/min were measured in the MCA. Lower volume flow rates were seen in subjects aged over 50 years (p < 0.01). When comparing women with men, a lower vessel area (p < 0.05) of the MCA was counterbalanced by a higher velocity, resulting in no significant difference of the volume flow rate. No difference occurred between the right and the left side. Flow reduction occurs in the elderly. A lower vessel area of the MCA in women is compensated by a higher velocity.

Adult↗
PubMed1999

Effect of combined mouth closure and chin lift on upper airway dimensions during routine magnetic resonance imaging in pediatric patients sedated with propofol.

BACKGROUND: In pediatric patients, obstruction of the upper airway is a common problem during general anesthesia. Chin lift is a commonly used technique to improve upper airway patency. However, little is known about the mechanism underlying this technique. METHODS: The authors studied the effect of the chin lift maneuver on airway dimensions in 10 spontaneously breathing children (aged 2-11 yr) sedated with propofol during routine magnetic resonance imaging. The minimal anteroposterior and corresponding transverse diameters of the pharynx were determined at the levels of the soft palate, dorsum of the tongue, and tip of the epiglottis before and during the chin lift maneuver. Additionally, cross-sectional areas were calculated at these sites, including tracheal areas 2 cm below the glottic level. RESULTS: Minimal anteroposterior diameter of the pharynx increased significantly during chin lift at all three levels in all patients. The diameters of the soft palate, tongue, and epiglottis increased from 6.7+/-2.8 mm (SD) to 9.9+/-3.6 mm, from 9.6+/-3.6 mm to 16.5+/-3.1 mm, and from 4.6+/-2.5 mm to 13.1+/-2.8 mm, respectively. The corresponding transverse diameter of the pharynx also increased significantly at all three levels in all patients but without significant predominance. The diameters at the levels of the soft palate, tongue, and epiglottis increased from 15.8+/-5.1 mm to 22.8+/-4.5 mm, from 13.5+/-4.9 mm to 18.7+/-5.3 mm, and from 17.2+/-3.9 mm to 21.2+/-3.7 mm, respectively. Cross-sectional pharyngeal areas increased significantly at all levels (soft palate, from 0.88+/-0.58 cm2 to 1.79+/-0.82 cm2; tongue, from 1.15+/-0.45 cm2 to 2.99+/-1.30 cm2; epiglottis, from 1.17+/-0.70 cm2 to 3.04+/-0.99 cm2), including the subglottic level (from 0.44+/-0.15 cm2 to 0.50+/-0.14 cm2). CONCLUSIONS: This study shows that all children had a preserved upper airway at all measured sites during propofol sedation. Chin lift caused a widening of the entire pharyngeal airway that was most pronounced between the tip of the epiglottis and the posterior pharyngeal wall. In pediatric patients, chin lift may be used as a standard procedure during propofol sedation.

Child↗
PubMed1999

Cerebral veins: comparative study of CT venography with intraarterial digital subtraction angiography.

BACKGROUND AND PURPOSE: Our objective was to compare the reliability of CT venography with intraarterial digital subtraction angiography (DSA) in imaging cerebral venous anatomy and pathology. METHODS: In 25 consecutive patients, 426 venous structures were determined as present, partially present, or absent by three observers evaluating CT multiplanar reformatted (MPR) and maximum intensity projection (MIP) images. These results were compared with the results from intraarterial DSA and, in a second step, with the results of an intraobserver consensus. In addition, pathologic conditions were described. RESULTS: Using DSA as the standard of reference, MPR images had an overall sensitivity of 95% (specificity, 19%) and MIP images a sensitivity of 80% (specificity, 44%) in depicting the cerebral venous anatomy. On the basis of an intraobserver consensus including DSA, MPR, and MIP images (415 vessels present), the sensitivity/specificity was 95%/91% for MPR, 90%/100% for DSA, and 79%/91% for MIP images. MPR images were superior to DSA images in showing the cavernous sinus, the inferior sagittal sinus, and the basal vein of Rosenthal. Venous occlusive diseases were correctly recognized on both MPR and MIP images. Only DSA images provided reliable information of invasion of a sinus by an adjacent meningioma. CONCLUSION: CT venography proved to be a reliable method to depict the cerebral venous structures. MPR images were superior to MIP images.

Adult↗
PubMed1999

Ruptured intracranial dermoid cyst.

Intradural dermoids are rare congenital tumors representing approximately 0.05% of all intracranial lesions. These benign tumors have a typical appearance on CT and MR due to their lipid components. The complication caused by rupture are the spillage of the fatty material into the cerebrospinal fluid. We report a case of a ruptured dermoid cyst showing fat/fluid levels in both side ventricles and fatty material in the subarachnoid space on CT and MR-imaging and the follow-up over four years after incomplete resection of the tumor.

Adult↗
PubMedDate not supplied

Percutaneous cervical vertebroplasty in a multifunctional image-guided therapy suite: hybrid lateral approach to C1 and C4 under CT and fluoroscopic guidance.

A 76-year-old patient suffering from two painful osteolytic metastases in C1 and C4 underwent percutaneous vertebroplasty by a hybrid technique in a multi-functional image-guided therapy suite (MIGTS). Two trocars were first placed into the respective bodies of C1 and C4 under fluoroscopic computed tomography guidance using a lateral approach. Thereafter, the patient was transferred on a moving table to the digital subtraction angiography unit in the same room for implant injection. Good pain relief was achieved by this minimally invasive procedure without complications. A hybrid approach for vertebroplasty in a MIGTS appears to be safe and feasible and might be indicated in selected cases for difficult accessible lesions.

Adenocarcinoma↗
PubMedDate not supplied

Prominent activation of the putamen during essential palatal tremor: a functional MR imaging case study.

Palatal tremor (PT), also known as palatal myoclonus, is defined by short rhythmic contractions of the palatal musculature. Functional MR imaging (fMRI) revealed prominent bilateral neuronal activation in the putamen associated with essential palatal tremor (EPT) in a 41-year-old man. This implies a central role of the putamen in EPT, most likely as a consequence of diminished inhibition in an afferent pathway. Because fMRI primarily detects activations, dysfunctional areas remain obscure. The present functional study complements previous pathologic studies, which associated PT with lesions to dentate nucleus, red nucleus, and the inferior olive (Guillain-Mollaret triangle).

Adult↗