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M Cohnen

Publications and source records attributed to M Cohnen.

44 records · Page 3Linked to original sources
PubMed1999

Reliability and validity of noninvasive imaging of internal carotid artery pseudo-occlusion.

BACKGROUND AND PURPOSE: Our study evaluated noninvasive tests for the diagnosis of atheromatous internal carotid artery (ICA) pseudo-occlusion. METHODS: Twenty patients (17 men, 3 women; mean age +/-SD, 64.3+/-11.6 years) with angiographically proven atheromatous ICA pseudo-occlusion (20 vessels) were prospectively examined with MR angiography (MRA; 2D and 3D time-of-flight techniques), color Doppler-assisted duplex imaging (CDDI) and power-flow imaging (PFI) with and without an intravenous ultrasonic contrast agent. As a control group, 13 patients (13 men; mean+/-SD age, 63.0+/-9.0 years) with angiographically proven ICA occlusion (13 vessels) were studied with the same techniques. For the determination of interobserver agreement (kappa statistics), the findings of each diagnostic technique were read by 2 blinded and independent observers who were not involved in patient recruitment and initial data acquisition. Specificity and sensitivity were calculated for all noninvasive techniques (observer consensus) in comparison to the standard of reference (intra-arterial angiography). RESULTS: Interobserver reliabilities were kappa=0.86 for intra-arterial angiography, kappa=0.90 for unenhanced CDDI, kappa=0. 93 for enhanced CDDI, kappa=0.93 for unenhanced PFI, kappa=1.0 for enhanced PFI, kappa=0.93 for 2D MRA, and kappa=0.77 for 3D MRA, respectively (P<0.0001). Specificities and sensitivities were 0.92 and 0.70 for unenhanced CDDI, 0.92 and 0.83 for enhanced CDDI, 0.92 and 0.95 for unenhanced PFI, 1.0 and 0.94 for enhanced PFI, 1.0 and 0.65 for 2D MRA, and 0.89 and 0.47 for 3D MRA, respectively. CONCLUSIONS: Advanced ultrasonographic techniques, especially PFI (with only 1 false-positive diagnosis of occlusion in the present series), can provide reliable and valid data to differentiate between ICA pseudo-occlusion and complete occlusion. In contrast, time-of-flight MRA at its present state is not capable of predicting minimal residual flow within a nearly occluded ICA.

Aged↗
PubMed1998

[POEMS syndrome. A rare variant of osteosclerotic multiple myeloma with polyneuropathy, organomegaly, endocrinopathy, M-gradient and skin lesions].

BACKGROUND: A rare multi-organ involvement in plasma-cell dyscrasias has been named POEMS-syndrome: it is a synopsis of monoclonal gammopathy (M-gradient), osteosclerotic bone lesions, peripheral polyneuropathy, organomegaly, endocrinopathy and skin lesions. CASE REPORT: A patient is presented who had a classical manifestation of this disease known mainly in Japan. A monoclonal IgA-lambda-gammopathy was determined as cause of a gradually progressive polyneuropathy. The patient had a hypergonadotropic hypogonadism, hyperprolactinaemia, and sclerotic bone lesions. In addition, he showed a changing organomegaly, and hyperpigmentation of the skin. CONCLUSION: As yet, aetiology and pathophysiology are not fully understood. Irradiation or surgical resection of one or several osteosclerotic bone lesions may improve the polyneuropathy or may even lead to a complete remission of all symptoms. Thus, monoclonal immunoglobulins should be searched for in any unclear polyneuropathy, as should be for other symptoms of the POEMS-syndrome.

Diagnosis, Differential↗
PubMed1998

[Dosage measurements in spiral CT examinations of the head and neck region].

PURPOSE: In view of the increasing frequency of computed tomographic examinations the organ doses of the thyroid gland and the eye lenses in spiral CT examinations of the head and neck should be determined. MATERIAL AND METHODS: Standard CT-examinations of the neck, the paranasal sinuses in axial and coronal sections, and the mandibula were simulated by help of an Alderson-Rando phantom. Dose measurements were performed as well in 28 patients. The examinations were carried out in spiral mode ("Somatom AR.SP", "Picker PQ 2000", and "Toshiba Xpress SX") and conventional single slice technique ("Somatom Plus"). Three LiF-TLD were placed on each eyelid and three on the thyroid. RESULTS: With direct exposure to the x-ray-beam the organ doses did not exceed 64 mGy. When exposed by scatter radiation only, doses may be reduced by a factor of up to 10. The measurements in 28 patients showed similar results. CONCLUSIONS: The organ doses in spiral CT correspond with data known from conventional CT.

Head↗
PubMed1998

Transjugular intrahepatic portosystemic shunts: improved evaluation with echo-enhanced color Doppler sonography, power Doppler sonography, and spectral duplex sonography.

OBJECTIVE: We assessed the feasibility of contrast-enhanced color Doppler, power Doppler, and spectral duplex sonography for visualization and quantification of flow through transjugular intrahepatic portosystemic shunts (TIPS) in patients in whom the baseline sonographic evaluation was unsatisfactory. SUBJECTS AND METHODS: Thirty-three patients underwent color Doppler, power Doppler, and spectral duplex sonography after TIPS insertion or before TIPS revision (mean time interval +/- SD, 1 +/- 1 day). All sonograms were obtained before and after patients received echo-enhancing contrast material. Sonography was evaluated with regard to presence or absence of flow in the mid portion, portal segment, and hepatic segment of the shunt. The maximal peak velocity was measured in the mid portion of the shunt. For identifying and quantifying stenoses, the percentage of luminal diameter reduction was calculated at the tightest part of the shunt. Shunt angiography and measurements of portosystemic pressure gradients were independently evaluated and compared with the sonographic findings. RESULTS: Flow visualization on unenhanced color Doppler sonography was significantly improved through the use of power Doppler sonography and contrast-enhanced color Doppler and power Doppler sonography (p < .01). Between contrast-enhanced power Doppler and contrast-enhanced color Doppler sonography, a significant difference was found in the portal and hepatic segments (p < .05). All shunt stenoses (n = 8) and occlusions (n = 3) were revealed by power Doppler sonography, whereas color Doppler sonography failed to reveal six of eight stenoses. Compared with unenhanced sonography, the quality of spectral duplex sonography was improved in eight patients after contrast enhancement (p < .05). Maximal peak velocity ranged from 54 to 252 cm/sec (mean +/- SD, 132.7 +/- 52.1 cm/sec) in normal shunts and from 24.5 to 70.0 cm/sec (mean +/- SD, 45.0 +/- 18.9 cm/sec) in stenosed shunts. No correlation was found between maximal peak velocity and portosystemic pressure gradients (r = .28). CONCLUSION: Unenhanced power Doppler and contrast-enhanced color and power Doppler sonography can be helpful in the assessment of TIPS status in patients who previously underwent unsatisfactory sonography. These techniques may allow anatomic evaluation and quantification of shunt stenosis in most patients. Contrast enhancement may also considerably improve the quality of spectral duplex sonography.

Adult↗
PubMed1998

[Possibilities for dose reduction in coronal spiral CT of the mid-face area].

The radiation dose at the eye lens and the thyroid gland in spiral-CT-examinations is comparable to those known from conventional computed tomography. In view of an increasing artificial radiation exposure, it remains an important aim to achieve dose reduction with persistent adequate imaging quality. We determined the doses of the named organs in four different CT-examination protocols by use of phantom studies and in 45 patients. By reduction of tube current and tube voltage, organ doses can be reduced by half. This is achieved without a relevant loss in diagnostic precision as far as high-contrast structures are concerned. Compared to conventional CT-scanning, the dose reduction reached 75%. Taking into consideration the increasing insensitivity in the z-plane and the worsening of the section-sensitivity profile, a properly chosen increase in pitch may result in a significant dose reduction. CT-scanning of high-contrast structures in the head and neck can and should be performed with the least radiation exposure possible.

Craniofacial Abnormalities↗
PubMed1997

Inhibition of beta-glucuronidase by casein hydrolysate formula.

BACKGROUND: A casein hydrolysate infant formula has been shown to be associated with lower levels of neonatal jaundice than are standard infant formulas. Because beta-glucuronidase is related to neonatal jaundice, this study examined the effect of a casein hydrolysate formula on beta-glucuronidase. METHODS: Beta-glucuronidase activity was measured with or without added dietary components. The beta-glucuronidase sources used were meconium, breast milk, and the purified bovine liver enzyme. The dietary components assayed for their effect on beta-glucuronidase activity included casein hydrolysate formula (Nutramigen), whey-predominant formula (Enfamil), breast milk; enzymatically hydrolyzed casein, and other constituents of the casein hydrolysate formula. Stool samples of 6-day-old infants, who were exclusively fed one of the two formulas or breast milk, were also assayed for inhibition of beta-glucuronidase. RESULTS: Only Nutramigen, enzymatically hydrolyzed casein, and stool from Nutramigen-fed infants consistently demonstrated significant inhibition of beta-glucuronidase activity, ranging from 45% to 85% of that in controls. The inhibition of beta-glucuronidase in purified bovine liver demonstrates a dose response in a pH range from 4 to 7.3. CONCLUSIONS: Hydrolyzed casein contains a beta-glucuronidase inhibitor that, in casein hydrolysate-fed infants, persists after passage through the digestive tract. These data are consistent with the possibility that inhibition of beta-glucuronidase is a mechanism by which infants fed casein hydrolysate have lower jaundice levels than infants fed routine formulas or breast milk. Further study of this mechanism is needed.

Animals↗
PubMed1995

[Tuberous sclerosis: typical complications of a hereditary disease and therapeutic options].

BACKGROUND: Tuberous sclerosis is an autosomal-dominant hereditary disease (incidence and prevalence 1:10,000) which is characterized by hamartomas in various organs. PATIENTS AND METHODS: We demonstrate three patients with different and partly atypical manifestations: All had facial angiofibroma. No patient was mentally retarded and epilepsy was observed only intermittently. In all cases periventricular calcifications were noted and renal angiomyolipomas were found. Two patients requested dialysis after nephrectomy. One patient suffered from severe complications of the rare pulmonary lymphangioleiomyomatosis. RESULTS: Therapy of this multiorgan disease is only symptomatic. Operations should be considered as second line treatment. In one case, successful renal transplantation is described. CONCLUSIONS: Genetic counselling is warranted in this disease with high penetrance, particularly the broad spectrum of manifestations should be taken into account.

Adult↗