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C D Claussen

Publications and source records attributed to C D Claussen.

At least 181 records · Page 10Linked to original sources
PubMed1999

[The nipple in MR mammography--the normal findings and the signs of disease].

PURPOSE: To differentiate between patterns of contrast enhancement in normal and pathologic nipples. MATERIALS AND METHODS: The examinations were performed on a 1.0 T imager, using a dynamic FLASH-3D-Sequence (9/3/50 degrees). The enhancement of nipples and normal breast parenchyma was evaluated retrospectively in 156 patients. In total, 277 nipples and the parenchyma of 101 patients could be evaluated. In 5 cases histologically confirmed pathologies were found. RESULTS: The 272 normal nipples were characterized by a slow and continuous increase of enhancement from 80% in the first minute to 300% in minute 10. The mean values of the normal parenchyma ranged from 20% in the first minute to 90% in minute 10. The five pathologic nipples showed a high initial signal increase reaching a maximum in the third minute (mean 400%) followed by a plateau. The enhancement of the normal nipples was of fine-linear morphology in the corium, while it was nodular for the pathologic nipples. CONCLUSION: Normal nipples show a slowly increasing fine-linear enhancement, higher than the enhancement of normal parenchyma. Nodular enhancement with a plateau or wash-out should be considered suspicious and a further work-up is necessary.

Adolescent↗
PubMed1999

[Cardiac MRI for determining functional left ventricular parameters].

PURPOSE: To prove the accuracy of MR methods in the determination of left ventricular (LV) functional parameters and anatomy. MATERIALS AND METHODS: At 1.5 T, 20 healthy volunteers and 22 patients with aortic valvular disease (stenosis n = 15, regurgitation n = 7) were examined. Functional parameters like cardiac output, ejection fraction, end-diastolic volume, aortic flow maximum, and time interval from the R-wave to maximum flow were obtained using a velocity encoding 2D FLASH sequence (TR 24 ms, TE 5 ms, venc 250 cm/sec) and segmented breath-hold cine FLASH 2D technique (TR 100 ms, TE 4.8 ms, flip angle 25 degrees, temporal resolution 50 ms). Invasive measurements (Fick principle) served as gold standard, intra- and interobserver variability were determined. RESULTS: Differences of functional parameters between normal volunteers and patients were detectable at a high level of significance (p < 0.0001). For cardiac output a superior correlation with the gold standard was found using flow measurements (r = 0.66, p < 0.0007) compared to volumetric calculations from cine studies (r = 0.47, p < 0.02). Interobserver variability was 2.5 +/- 2.7%/4.5 +/- 6.9% (flow quantification/calculations from cine studies), intraobserver variability was 1.7 +/- 1.6%/3.3 +/- 2.2%. CONCLUSIONS: MRI is an appropriate tool for determining LV functional parameters and anatomy. Differences between normal volunteers and patients with aortic valvular disease can be detected reliably. Flow measurements turned out to be more accurate than calculations from cine images. Therefore, flow quantification techniques should be preferred for clinical use.

Adult↗
PubMed1999

[Value of CT in diagnosis of respirator-associated pneumonia].

PURPOSE: To analyse the diagnostic accuracy of computed tomography (CT) in ventilator-associated pneumonia (VAP). MATERIALS AND METHODS: 23 patients on mechanical ventilation with a new pulmonary abnormality on chest X-ray were examined with both spiral-CT and high-resolution CT. The diagnosis VAP was made according to prospectively defined criteria. Bronchoscopic specimen asservation with protected specimen brushing (PSB) served as gold standard. RESULTS: With PSB, 11 of 23 patients were found to have VAP. CT showed a sensitivity and specificity of 53% and 63%, respectively. Ground glass infiltrates appeared to have a 100% specificity but were found in only 5/11 patients. CONCLUSIONS: CT is not the method of choice for diagnosing VAP. Ground glass infiltrates seeming to be highly specific are only inconstantly found.

Adult↗
PubMed1999

[Diagnosis of renal artery stenosis in 1.0 T using 3D phase contrast magnetic resonance angiography and dynamic contrast medium perfusion].

PURPOSE: To assess renal artery stenosis (RAS) by 3D phase contrast (PC) MR angiography and dynamic perfusion imaging of the kidneys. METHODS: On a standard 1.0 T MR imaging system (Magnetom Expert, Siemens), 32 patients with angiographically proven unilateral RAS were examined using a 3D PC sequence (TR 40 ms/TE 9 ms/venc 30 cm/s). An ECG-gated Turbo-FLASH 2D sequence (TR 4.5 ms/TE 2.2 ms/TIeff. 400 ms) was applied to study the first pass of paramagnetic contrast agent (0.1 mmol Gd-DTPA/kg) through the kidneys. Signal intensity (SI) over time curves of the renal cortex were obtained and evaluated considering temporal relation and percentage of maximum SI compared to the aorta and normal kidneys. Analysis of the MRA was performed by two independent blinded readers. The gold-standard DSA was interpreted by consensus reading of two experienced radiologists. RESULTS: RAS was detected by 3D PC MRA with a sensitivity of 93% and specificity of 81% (ppv 82%, npv 93%, accuracy 87%, kappa = 0.61). Maximum SI in RAS was significantly decreased (p < 0.001-0.0001). A temporally delayed enhancement of 1.5 +/- 1.3 s was found for RAS > 75% (p < 0.002) but not for RAS < 75% (p > 0.1). CONCLUSIONS: 3D PC MRA is capable of detecting RAS in a high percentage of patients. Dynamic perfusion imaging of the kidneys, applied additionally, can confirm the diagnosis and give valuable information about the hemodynamic relevance of RAS in suspected unilateral disease.

Contrast Media↗
PubMed1999

[MR tomography of the bone marrow changes after high-dosage chemotherapy and autologous peripheral stem-cell transplantation].

PURPOSE: Evaluation of MR standard imaging and short time inversion recovery (STIR) imaging to assess changes in red bone marrow cellularity after high-dose chemotherapy (HDC) and peripheral blood stem cells transplantation (PBSCT). MATERIALS AND METHODS: Sixty-one magnetic resonance (MR) studies were performed in 15 patients (8 female and 7 male, average age 45 years) who received HDC and PBSCT for therapy of either a solid tumor or multiple myeloma. All patients underwent MR examinations of the lumbar region and both femora with T1- and T2-weighted turbo spin-echo (TSE) and STIR sequences at predefined time intervals. Qualitative analysis of the signal intensity was performed by consensus reading of four radiologists. MR results were correlated with results of blood smears and marrow histology. RESULTS: STIR sequences demonstrated marked changes in signal intensity not only until the aplasia occurred but also during bone marrow repopulation. An increased signal intensity was observed after HDC in 13/15 patients (87%), followed by a decrease in signal intensity immediately after aplasia in 14/15 patients (93%). Signal intensity further changed parallel to marrow engraftment in 11/15 patients (73%). T2-TSE only showed clear changes during repopulation in 8/15 patients (53%). The individual course of the signal in T1-TSE was markedly inhomogeneous. CONCLUSIONS: STIR sequences show bone marrow edema during aplasia and marrow cellularity during reconstitution and are suitable for characterisation of red bone marrow after HDC and autologous PBSCT.

Adult↗
PubMed1999

MR findings in primary retroperitoneal schwannoma.

OBJECTIVE: To evaluate the MR findings in primary retroperitoneal schwannoma. MATERIAL AND METHODS: Seven cases of primary retroperitoneal schwannoma, in whom the diagnosis was confirmed histopathologically, were analyzed retrospectively. The following items were reviewed at MR imaging: tumor diameter, margin, homogeneity, signal intensity as compared to normal renal parenchyma, presence/absence of infiltration into adjacent organs, and, in 1 and 4 cases, the enhancement on Gd-dynamic images and post-contrast T1-weighted images, respectively. RESULTS: Tumor diameter was 5.5 +/- 3.1 cm, ranging from 2.5 to 10 cm in the 6 benign schwannomas, and 12 cm in 1 malignant. The tumor margin was regular in all of the benign cases and irregular in the malignant one. The malignant case showed infiltration into the liver and duodenum. Four of the benign schwannomas showed a homogeneous, and 2 presented a heterogeneous pattern, while the malignant schwannoma was heterogeneous. On T1-weighted images, the benign schwannomas were hypointense in 4 cases, isointense in 1 and mixed in 1, while on T2-weighted images, they were hyperintense in 5 and mixed in 1. The malignant case showed mixed intensity on both T1- and T2-weighted images. On enhanced T1-weighted images, capsular, septal enhancement was noted in 2 cases, overall enhancement in 2, and, on Gd-dynamic images, late enhancement was shown. CONCLUSION: On MR imaging, primary retroperitoneal schwannomas show different signal intensity characteristics, including cystic degeneration. There are, however, no specific characteristics of these tumors.

Aged↗
PubMed1999

Suture-mediated percutaneous closure of antegrade femoral arterial access sites in patients who have received full anticoagulation therapy.

PURPOSE: To assess the feasibility and clinical usefulness of suture-mediated closure of femoral arterial access sites after antegrade puncture for peripheral arterial interventions. MATERIALS AND METHODS: Eighty consecutive patients (49 men, 31 women; mean age +/- SD, 65.4 years +/- 12.3) who had undergone femoropopliteal angioplasty underwent suture-mediated percutaneous closure with 6-, 7-, or 8-F devices. Patients received heparin intravenously and aspirin orally and were immobilized for 1 hour after the intervention. All patients underwent a physical examination the day after the procedure. Color-coded duplex ultrasonography was performed in those patients (n = 27 [33%]) who were obese, were experiencing pain, and had suspicious clinical findings. After 3 months, an identical clinical examination was performed in every third patient. RESULTS: Hemostasis was achieved in 77 (96%) patients; one of 80 patients required blood transfusions and surgery despite an initially successful closure. The closure devices could be deployed in 78 (98%) patients; two of 80 patients needed compression because of a steep angulation of the puncture track and suture entrapment. Adjunctive compression was necessary in two (3%) of the remaining 78 patients. Mean time to hemostasis in the 78 patients who had successful device deployment was 5.2 minutes (range, 3.0-21.0 minutes). Minor complications (i.e., three small hematomas, a pseudoaneurysm, and a small lymphatic fistula) occurred in five (6%) patients. CONCLUSION: Suture-mediated percutaneous closure of antegrade puncture sites in the groin is feasible. Problems may arise in antegrade punctures owing to steep device angulation.

Aged↗
PubMed1999

Inverted papilloma of the nasal cavity and the paranasal sinuses: using CT for primary diagnosis and follow-up.

OBJECTIVE: Morphologic criteria for the diagnosis of primary and recurrent inverted papilloma as revealed on CT were evaluated in a large series. MATERIALS AND METHODS: Findings of 121 CT examinations that had been performed in 32 patients with histologically proven inverted papilloma were retrospectively analyzed using the following morphologic criteria: localization, size, surface configuration, and bony changes. RESULTS: Unilateral tumor localization involving the lateral nasal wall and the middle meatus was the feature that best correlated with the finding of primary inverted papilloma. A lobulated surface pattern was another typical sign, which was revealed on 19 of the 29 CT scans of patients with primary inverted papilloma. Although tumor localization and the finding of a newly grown soft-tissue mass were less reliable criteria to differentiate between recurrent inverted papilloma and postoperative complications or concomitant inflammatory disease, a lobulated surface pattern was seen on 26 of the 28 CT scans of patients with tumor recurrence but on only three of the 64 follow-up CT scans of patients without recurrent inverted papilloma. CONCLUSION: A unilateral mass within the nasal cavity or paranasal sinuses with a surface configuration that appears lobulated on CT is, to our knowledge, a new sign that strongly suggests inverted papilloma as a primary diagnosis and also suggests inverted papilloma in patients with tumor recurrence.

Adult↗
PubMed1999

Platelet glycoprotein IIb/IIIa receptor antagonist used in conjunction with thrombolysis for peripheral arterial thrombosis.

OBJECTIVE: This feasibility study was designed to evaluate the therapeutic potential of intraarterial urokinase combined with abciximab, an IV platelet glycoprotein IIb/IIIa receptor antagonist, in peripheral arterial thrombosis. CONCLUSION: The administration of a highly potent glycoprotein IIb/IIIa inhibitor in conjunction with intraarterial fibrinolysis was safe in 14 patients. One distal embolization and no major bleeding occurred. The primary success rate was 100%. Treatment times ranged from 50 min to 8 hr. We found a reocclusion rate of 7% (1/14) at intermediate follow-up.

Abciximab↗
PubMed1999

MR angiography and flow quantification of the internal mammary artery graft after minimally invasive direct coronary artery bypass.

OBJECTIVE: Six patients who had undergone minimally invasive direct coronary artery bypass surgery were examined to evaluate an MR imaging protocol that provided information about cardiac function, bypass graft patency, and flow characteristics with a single examination. CONCLUSION: Preliminary results suggest that our imaging protocol allows accurate follow-up of patients after minimally invasive direct coronary artery bypass surgery. Bypass graft patency was correctly determined in all patients. In four patients, anastomoses were visualized by MR angiography, and flow measurements revealed a volume range of 28-84 ml/min (native and grafted internal mammary arteries) and a trend for the flow values of bypass grafts to be lower than those of native vessels. Interobserver reproducibility was good (r = .99; slope, .98).

Contrast Media↗
PubMed1999

Renal MR angiography at 1.0 T: three-dimensional (3D) phase-contrast techniques versus gadolinium-enhanced 3D fast low-angle shot breath-hold imaging.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic usefulness of three different MR angiographic techniques at 1.0 T. SUBJECTS AND METHODS: In 22 patients with renal artery stenosis confirmed at intraarterial catheter angiography, we also performed unenhanced and gadolinium-enhanced three-dimensional phase-contrast MR angiography and gadolinium-enhanced single breath-hold three-dimensional fast low-angle shot MR angiography. We determined circulation time to optimize signal acquisition in gadolinium-enhanced breath-hold MR angiography after bolus injection of contrast material. RESULTS: Sensitivity, defined as the detection of a hemodynamically significant stenosis (>50% luminal narrowing), was 85% for enhanced phase-contrast MR angiography, 91% for gadolinium-enhanced MR angiography, and 95% for unenhanced phase-contrast MR angiography. The combination of unenhanced phase-contrast MR angiography and gadolinium-enhanced MR angiography yielded 100% sensitivity for hilar artery stenoses. There were 13 false-positive findings with unenhanced phase-contrast MR angiography, 10 with enhanced phase-contrast MR angiography, and four with gadolinium-enhanced MR angiography (specificity: 38%, 52%, and 79%, respectively). Accessory renal arteries were not seen on unenhanced or enhanced phase-contrast MR angiography (0/8 patients) but were detected with gadolinium-enhanced MR angiography in five of the eight patients. Interobserver agreement (kappa = .62) was best with gadolinium-enhanced MR angiography. The quality of the images was unsatisfactory for adequate evaluation of segmental renal arteries with all three MR angiographic techniques. CONCLUSION: A combination of unenhanced phase-contrast MR angiography and gadolinium-enhanced MR angiography at 1.0 T proved useful as a screening protocol for renal artery stenosis.

Adult↗
PubMed1999

Association of increased intramyocellular lipid content with insulin resistance in lean nondiabetic offspring of type 2 diabetic subjects.

Insulin resistance plays an important role in the pathogenesis of type 2 diabetes; however, the multiple mechanisms causing insulin resistance are not yet fully understood. The aim of this study was to explore the possible contribution of intramyocellular lipid content in the pathogenesis of skeletal muscle insulin resistance. We compared insulin-resistant and insulin-sensitive subjects. To meet stringent matching criteria for other known confounders of insulin resistance, these individuals were selected from an extensively metabolically characterized group of 280 first-degree relatives of type 2 diabetic subjects. Some 13 lean insulin-resistant and 13 lean insulin-sensitive subjects were matched for sex, age, BMI, percent body fat, physical fitness, and waist-to-hip ratio. Insulin sensitivity was determined by the hyperinsulinemic-euglycemic clamp method (for insulin-resistant subjects, glucose metabolic clearance rate [MCR] was 5.77+/-0.28 ml x kg(-1) x min(-1) [mean +/- SE]; for insulin-sensitive subjects, MCR was 10.15+/-0.7 ml x kg(-1) x min(-1); P<0.002). Proton magnetic resonance spectroscopy (MRS) was used to measure intramyocellular lipid content (IMCL) in both groups. MRS studies demonstrated that in soleus muscle, IMCL was increased by 84% (11.8+/-1.6 vs. 6.4+/-0.59 arbitrary units; P = 0.008 ), and in tibialis anterior muscle, IMCL was increased by 57% (3.26+/-0.36 vs. 2.08+/-0.3 arbitrary units; P = 0.017) in the insulin-resistant offspring, whereas the extramyocellular lipid content and total muscle lipid content were not statistically different between the two groups. These data demonstrate that in these well-matched groups of lean subjects, IMCL is increased in insulin-resistant offspring of type 2 diabetic subjects when compared with an insulin-sensitive group matched for age, BMI, body fat distribution, percent body fat, and degree of physical fitness. These results indicate that increased IMCL represents an early abnormality in the pathogenesis of insulin resistance and suggest that increased IMCL may contribute to the defective glucose uptake in skeletal muscle in insulin-resistant subjects.

Adult↗
PubMed1999

[In-vivo 1H-MR spectroscopy: the determination of the intra- and extramyocellular lipid content depending on the insulin effect in the direct offspring of type-2 diabetics].

PURPOSE: Differentiation and assessment of intra- (IMCL) and extramyocellular lipids (EMCL) in offspring of type II diabetic subjects by means of 1H-MR spectroscopy. METHODS: Out of a group of more than 250 metabolically characterized offspring of type II diabetics, twenty subjects were selected and matched for anthropometric parameters. Glucose clamp was performed prior to MRS in all subjects for metabolic characterization. Ten individuals were classified as insulin resistant (MCR < 7 ml/kg/min) and ten were found to be insulin sensitive (MCR > 7 ml/kg/min). MRS was performed in the tibialis anterior muscle and in the soleus muscle. RESULTS: For insulin resistant individuals the MRS results revealed a higher IMCL content in both muscles. In the tibialis anterior muscle IMCL was increased by 1.6 fold (arbitrary units +/- SEM: 3.2 +/- 0.4 vs 2.0 +/- 0.3; p < 0.01) and in the soleus muscle by 2.0 fold (arbitrary units +/- SEM: 13.0 +/- 1.9 vs 6.6 +/- 0.9; p < or = 0.01). There was no correlation between EMCL and MCR in the soleus muscle. In addition, no relationship between the amount of IMCL and the subcutaneous fat layer was found. CONCLUSIONS: A significantly increased intramyocellular lipid content in insulin resistant offspring of type II diabetic subjects was assessed non-invasively by 1H-MR spectroscopy.

Adult↗
PubMed1999

Ultrafast diffusion-sensitive MR imaging of brain on an open scanner at 0.2 T.

We describe new strategies for fast diffusion-sensitive MR imaging of ischemic brain or spinal cord lesions. The methods provide diagnostic image quality in less than 1 s per section and are used in conjunction with low-field-strength open MR scanners. Single-shot sequences combine diffusion-sensitive preparation with a modified fast spin-echo data acquisition. Results are presented from healthy volunteers and from two patients with recent and older ischemic brain lesions.

Adult↗
PubMed1998

Remote suturing for percutaneous closure of popliteal artery access.

We present a case of balloon angioplasty of the superficial femoral artery via a popliteal artery access with successful percutaneous vascular closure of the vascular access site (6-F Techstar). A femoral arterial approach had not been feasible due to previous aorto-femoral and femoro-femoral bypass operations. Clinical and ultrasound follow-up showed no complications up to 3 months after remote suturing.

Aged↗
PubMed1998

Percutaneous arterial closure in severely scarred groins: a technical note.

We present a new method to enable the insertion of percutaneous suturing devices in severely scarred groins, using a peel-away sheath. This sheath stabilizes the percutaneous tract for the suturing device. It may help to salvage closure procedures, which would otherwise have to be aborted due to insufficient stiffness of the device shaft.

Catheters, Indwelling↗
PubMed1998

[Yamakawa prosthesis with prolonged placement as a therapy concept exemplified by benign biliary stricture].

AIM: As an alternative method to the operative revision of benign bile duct strictures, we report the use of a large-bore bile duct prosthesis (Yamakawa prosthesis) in one patient. METHODS: Bilateral percutaneous transhepatic implantation of Yamakawa prostheses (14 F right side, 12 F left side) was performed without adjunctive balloon dilatation. The prostheses were exchanged every 8 weeks under continuous antibiotic treatment and were finally removed after 8 months. RESULTS: Control cholangiography showed a normal intrahepatic biliary system on the right side and a 50% stenosis at the orifice of the left hepatic duct. Follow-up over 18 months showed no signs of recurrent disease. CONCLUSIONS: In comparison to balloon dilatation and implantation of metallic stents, prolonged bilateral splinting with large-bore Yamakawa prostheses seems to be an alternative for the treatment of benign bile duct strictures.

Adult↗