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C Claussen

Publications and source records attributed to C Claussen.

At least 19 recordsLinked to original sources
PubMed2000

Focal liver lesions: evaluation of the efficacy of gadobenate dimeglumine in MR imaging--a multicenter phase III clinical study.

PURPOSE: To evaluate gadobenate dimeglumine (Gd-BOPTA) for dynamic and delayed magnetic resonance (MR) imaging of focal liver lesions. MATERIALS AND METHODS: In 126 of 214 patients, MR imaging was performed before Gd-BOPTA administration, immediately after bolus administration of a 0.05- mmol/kg dose of Gd-BOPTA, and 60-120 minutes after an additional intravenously infused 0.05-mmol/kg dose. In 88 patients, imaging was performed before and 60-120 minutes after a single, intravenously infused 0.1-mmol/kg dose. T1- and T2-weighted spin-echo and T1-weighted gradient-echo images were acquired. On-site and blinded off-site reviewers prospectively evaluated all images. Intraoperative ultrasonography, computed tomography (CT) during arterial portography, and/or CT with iodized oil served as the reference methods in 110 patients. RESULTS: Significantly more lesions were detected on combined pre- and postcontrast images compared with on precontrast images alone (P <. 01). All reviewers reported a decreased mean size of the smallest detected lesion and improved lesion conspicuity on postcontrast images. All on-site reviewers and two off-site reviewers reported increased overall diagnostic confidence (P <.01). Additional lesion characterization information was provided on up to 109 (59%) of 184 delayed images and for up to 50 (42%) of 118 patients in whom dynamic images were assessed. Gd-BOPTA would have helped change the diagnosis in 99 (47%) of 209 cases and affected patient treatment in 408 (23%) of 209 cases. CONCLUSION: Gd-BOPTA increases liver lesion conspicuity and detectability and aids in the characterization of lesions.

Adult↗
PubMed1999

Correlation of imaging techniques to histopathology in patients with diabetic foot syndrome and clinical suspicion of chronic osteomyelitis. The role of high-resolution ultrasound.

OBJECTIVE: To investigate the role of ultrasound in the diagnosis of osteomyelitis in the diabetic foot compared with magnetic resonance imaging (MRI), bone scintigraphy (BS), and plain film radiography (PFR). RESEARCH DESIGN AND METHODS: We investigated 19 consecutive diabetic patients (2 women, 17 men, age 60.7 +/- 9.8 years, BMI 27.0 +/- 3.8 kg/m2) with clinical suspicion of bone infection of the foot. A high-resolution ultrasound system (Esaote/Biosound, Munich) with a linear array transducer up to 13.0 MHz was used. The prospective and blinded results of each method were compared with histopathology as the reference method after metatarsal resection. RESULTS: In 14 of 19 patients, histopathology confirmed osteomyelitis. Ultrasound showed a sensitivity of 79% (PFR, 69%; BS, 83%; MRI, 100%), a specificity of 80% (PFR, 80%; BS, 75%; MRI, 75%), a positive predictive value of 92% (PFR, 90%; BS, 91%; MRI, 93%), and a negative predictive value of 57% (PFR, 50%; BS, 60%; MRI, 100%). CONCLUSIONS: Our data indicate that ultrasound might have a better diagnostic power for detecting chronic osteomyelitis in the diabetic foot than PFR and has similar sensitivity and specificity as BS. MRI is superior to the other three methods. We conclude that the use of ultrasound in the management of the diabetic foot is worthy of further investigation.

Diabetic Foot↗
PubMed1996

Vestibular Evoked Potentials (VestEP) and Brain Electrical Activity Mapping - A Test of Vestibular Function - A Review (1990 - 1996).

Brain Electrical Activity Mapping of Vestibular Evoked Potentials (BEAM-VestEP) is a new technology for investigation of the spatial and temporal properties of a rotationally-induced brain electrical events. The method consists of multichannel EEG registration and mapping of the brain isoelectrical contours during short-lasting repetitive angular accelerations. A special data bank containing more than 400 BEAM-VestEP investigations on more than 300 persons, either symptom free volunteers or neurotological patients suffering from vertigo, tinnitus, sudden hearing loss, acoustic tumors, balance disorders, has been created for this study. The VestEP wave set consists of 5 - 7 positive/negative wave components, appearing within the time interval of 70 - 850 ms after the onset of the acceleratory step stimulus. The principle components analysis reveals that the shortest latencies and the highest amplitudes of the VestEPs can be registered from the central transversal line of electrodes, T3-C3-Cz-C4-T4. The later components are generated from the more frontally located cortical areas. The VestEP is a compound electrical phenomenon. The initial complex ( waves I - III) is related to the activation of specific (vestibular) cortical areas. The later complex (waves IV - VI) reflects the supramodal cortical proceedings with sensory information (cognitive components).

Journal Article↗
PubMed1996

Vestibular Evoked Potentials in Two Patients with Bilateral Vestibular Loss.

The Brain Electrical Activity Mapping (BEAM) of Vestibular Evoked Potentials (VestEP) is a new method in the toolbox of the neurootologist. Two cases of bilateral vestibular loss, diagnosed by classical neurootological methods (highlighted by caloric and optokinetic tests' electronystagmography recording), are reported. The additional information, provided by the Vestibular Evoked Potentials (VestEP) and its high clinical significance for a more accurate neurootologic diagnosis are discussed.

Journal Article↗
PubMed1995

On the Functional State of Central Vestibular Structures in Monoaural Symptomatic Tinnitus Patients (BEAM-VbEP Study).

Clinical evidence suggests that over-excitation or disinhibition of structures in the brain occurs in tinnitus patients.(1,2) Brain electrical activity mapping of vestibular evoked potentials (BEAM-VbEP method) provides an electrophysiologic approach of quantification of function in brain cortex. The effect of tinnitus on the BEAM-VbEP image was examined in two groups of acoustic tumor patient Group A (n = 24) reported tinnitus and Group B (n = 22) did not. Statistically significant differences in the VbEP parameters have been identified between the two groups. The amplitude of the III/IV peak-to-peak component elicited by the rotation to the affected side, is higher (P < 0.05) in the tinnitus group than in the non-tinnitus group. Latencies of the late VbEP components (III, IV, and V) are shorter. In subgroup III, latency was 317.9 +/- 37.5 ms in the tinnitus group versus 335.5 +/- 30.9 ms in non-tinnitus group (p < 0.05); subgroup IV's component of 437.1 +/- 35.4 ms versus 470.9 +/- 43.5 ms ( p < 0.01), V 622.1 +/- 32.6 versus 655.5 +/- 46.6 ms (p < 0.05). Amplitude mapping of the most prominent VbEP component, subgroup III, demonstrates a well expressed negativity shift of the evoked brain electrical activity. The character of the electrophysiologic VbEP changes in the group of tinnitus patients is irritative. We consider the above described BEAM-VbEP images in tinnitus patients to reflect an electrophysiologic correlative of a state of cortical disinhibition, caused by either hyperactive or hypersensitive neural structures. Tinnitus is an aberrant perception of sound unrelated to an external source of acoustic stimulation; a dysynchrony within the auditory system.(3-5) Does tinnitus originate from hyperactive nerve fibers in the cochlea or is it a consequence of overexcited or disinhibited brain structures?(6,7) This basic question still has no acceptable solution. One working hypothesis is that tinnitus represents periodic or aperiodic excitation in the spontaneous activity of hair cells or nerve fibers originating from a restricted place on the basilar membrane.(8) In most clinical cases, the complaint of tinnitus is an accompanying symptom of other central or peripheral disorders (cerebrovascular and circulatory diseases, acoustic neuromas, sudden hearing loss, intoxication, side effects of drugs, among others which frequently cause various degrees of hearing loss with a corresponding decrease in the spontaneous activity of the auditory nerve.)(9,10) Thus, one could imagine such cases of tinnitus can be caused by some abnormal form of spontaneous activity in the central nervous system. Such considerations influenced us to evaluate the functional state of the brain in patients in whom tinnitus is the chief complaint. The method used in this study is the BEAM-VbEP method. This approach for vestibular stimulation and recording is suggested by the original concept of Shulman and colleagues,(5,11) that in some cases tinnitus can originate at the site of vestibular dysfunction. Furthermore, the BEAM-VbEP method provides data restricted not only to vestibular brain centers and pathways, but also to a much broader perspective to sensory pathways and associative cortical areas.

Journal Article↗
PubMed1991

Gadopentetate dimeglumine as a bowel contrast agent: safety and efficacy.

To determine the safety and efficacy of gadopentetate dimeglumine as a bowel contrast agent, magnetic resonance (MR) imaging (0.5 T) was performed with a formulation of gadopentetate dimeglumine (1.0 mmol/L of gadopentetate dimeglumine, 15 g/L of mannitol, 6-17 mL/kg) in 133 patients with intraabdominal mass lesions. Mostly short-lived gastrointestinal side effects were noted in 32% of patients. Gadopentetate dimeglumine provided uniform hyperintense marking of the bowel and contrast enhancement in the region of interest in 81% of patients. Among 78 patients with images obtained both before and after administration of contrast material, post-contrast improvement of lesion delineation was found in 62%. Among 55 patients with only postcontrast images, gadopentetate dimeglumine proved useful in 65%. Intravenous injection of scopolamine or glucagon effectively eliminated "ghost" images of the opacified bowel in 105 of 109 cases. The authors conclude that gadopentetate dimeglumine is a safe and effective bowel contrast agent for MR imaging.

Adolescent↗
PubMed1989

[MRT of intrathoracic space-occupying lesions--conventional and new rapid study technics].

100 patients with histologically and cytologically confirmed intrathoracic space-occupying growths were examined by CT and MR over and above conventional x-ray film diagnosis. MR tomography was performed in all the 100 patients via ECG-triggered T1 and T2 weighted spin echo sequences. The last 35 patients were additionally examined via gradient echo sequences with which it is possible to examined 24 consecutive layers in any layer plane within 7 minutes without ECG triggering. Comparative evaluation of CT and MR tomography yielded an equally high degree of sensitivity when identifying intrathoracic growths. Compared to CT, determination of tumour status via MR tomography proved easier in individual cases. Other advantages of MR tomography were seen in the staging of bronchial carcinomas. Compared with conventional spin echo sequences the rapid gradient echo sequences reduced examination periods by more than 50%. In the cardiac region and the mediastinal structures that pulsate with it the diagnostic value of the gradient echo images is at present slightly impaired by fuzziness caused by movement. The image quality of the spin echo images is comparatively good in the regions of the superior and posterior mediastinum, the lungs and the thoracic wall.

Carcinoma, Bronchogenic↗
PubMed1988

CT reconstruction technique in lumbar intraneuroforaminal disc herniation.

The CT appearance of the lumbar neural foramina and contents is described in detail and compared to histopathological specimens. Direct axial scans with secondary sagittal, coronal and paraxial reconstruction series of slices of the neural foramen were derived from lumbar spine examination of fifty normal adults. These normal parameters were then used to evaluate and subdivide 20 patients with disc herniation involving the neural foramen. The new paraxial reformation was able to show an intraneuroforaminal disc involvement. CT-reformation technique and operative results in intraneuroforaminal disc herniation correspond in 80%. This improvement in preoperative diagnosis demonstrates to the neurosurgeon the full extent of disc herniation and results in an optimized operative approach.

Adult↗
PubMed1988

[Oral contrast media for magnetic resonance tomography of the abdomen. III. Initial patient research with gadolinium-DTPA].

32 patients with abdominal tumours or inflammatory abdominal diseases were examined by MRI (0.5 T) prior to and after oral administration of gadolinium-DTPA (Gd-DTPA). T1- and T2-weighted sequences were employed. 10 ml/kg body weight of a Gd-DTPA formulation were administered (1.0 mmol/l, 15 g mannitol/l). Gd-DTPA provided markedly hyperintensive opacification of the gastrointestinal tract. In 19 of 32 studies Gd-DTPA-enhanced scans showed improved delineation of abdominal pathologies. In most cases Gd-DTPA-enhanced T1-weighted multislice gradient echo images provided the most useful diagnostic result. Meteorism and diarrhea were recorded in 13 patients.

Abdomen↗
PubMed1988

[Scrotal changes in the 3.5 MHz ultrasound image].

Sonography enables sensitive detection of pathological changes in the scrotum, since the planes of intersection can be selected as may be required, and since local resolution is excellent. However, sonographic criteria alone do not permit differential diagnosis of malignomas against benign changes. Anamnesis and clinical examination are of equal importance as sonography. Diagnostic conclusions are possible only if all the findings based on all the diagnostic approaches are combined in synopsis. Although reports published in recent years postulated transducer either of a frequency higher than 3.5 mHz (1, 5, 11, 12, 13, 14, 17, 20, 21, 24, 25, 27) or low-frequency transducers associated with immersion technique (7, 23), in our patients the use of a 3.5 mHz convex scanner with water forerun resulted always in confirming the diagnosis (in conjunction with anamnesis and clinical findings). In our experience a transducer of this frequency (3.5 mHz) with water forerun appears to be suitable for routine diagnosis of changes in the scrotum. This is an important aspect in general practice, where ultrasound equipment is often fitted with 3.5 mHz transducers.

Diagnosis, Differential↗
PubMed1987

[Oral contrast media for magnetic resonance tomography of the abdomen. 1. Comparative animal studies of positive and negative contrast media].

Beagle dogs were investigated by MRI (Siemens Magnetom, 0.35 T) after oral administration of aqueous solutions of Gd-DTPA (n = 4), ferric ammonium citrate (n = 1), and magnetite dextran (n = 2). High signal intensity of the GI-tract versus adjacent structures was obtained with Gd-DTPA and ferric ammonium citrate. Magnetite showed negative contrast versus adjacent structures. However, magnetite displayed lower contrast relative to liver, muscle and gut wall compared to Gd-DTPA and ferric ammonium citrate. In relatively T2-weighted sequences labeling of poorly filled bowel loops was significantly better with Gd-DTPA and ferric ammonium citrate. For GI-tract contrast enhancement we conclude that positive contrast media are of higher diagnostic value compared to negative contrast agents.

Abdomen↗
PubMed1986

CT of the postoperative lumbar spine: the value of intravenous contrast.

Sixty-five patients with recurrent radicular complaints after operation for lumbar disc herniation underwent CT examination before and after intravenous contrast application (volume: 1.5-2.0 ml/kg body weight; flow rate: 0.35 ml/s). Postsurgical hypertrophic scar tissue showed definite contrast enhancement, whereas disc herniation remained unenhanced. Intravenous contrast application is recommended in patients previously operated upon for disc herniation.

Cicatrix↗