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T Sommer

Publications and source records attributed to T Sommer.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Quantitative evaluation of the suitability of magnetic resonance sequences for the detection of spinal bone marrow metastases of solid tumors].

AIM: To compare MR sequences for the examination of the bone marrow of the spine in the detection of skeletal metastases. METHODS: 20 standardised prospective studies of the cervical, thoracic or lumbar spine in patients with known skeletal metastases were evaluated quantitatively. Studies included T1w SE with and without intravenous contrast medium (CM) administration of Gd-DTPA, T2w TSE with and without frequence selective fat saturation (SPIR), opposed phase gradient echo (opGE) with and without intravenous CM administration of Gd-DTPA and T1w SE CM SPIR sequences. The quantitative parameters signal/noise ratio (SNR), contrast/noise ratio (CNR) and contrast were evaluated. RESULTS: OpGE with contrast showed the best results in SNR, CNR and C. Results were statistically significant. Good SNR and C also was found for T1w SE native. SPIR and T2w sequences were less sensitive. CONCLUSION: OpGE sequences are recommended for the detection of skeletal metastases of the spine.

Bone Marrow Neoplasms↗
PubMed1998

[MRI in patients with cardiac pacemakers: in vitro and in vivo evaluation at 0.5 tesla].

PURPOSE: MRI is currently regarded as absolutely contraindicated in patients with implanted cardiac pacemakers. In this prospective study safety and feasibility of MRI in patients with new generation pacemakers (PM) was evaluated in vitro and in vivo. METHODS: 14 PM models in vitro and 18 patients with implanted new generation PM underwent a MRI exam at 0.5 Tesla with standard spin, turbo spin, and gradient echo (FFE) sequences under continuous ECG-monitoring. PM inquiry was performed before and after the MRI exam, including assessment of stimulation thresholds. RESULTS: In the static magnetic field all PM switched to the asynchronous mode due to activation of the Reed switch, resulting in continuous pacing at a fixed rate. In three PM models in vitro, however, after activation of the Reed switch, there was a software-induced switch back to the demand mode. In these PM inhibition and triggering were observed after starting the MRI scan due to influence of the pulsed magnetic fields. PM program changes, damage of PM components, dislocation/torque of the PM and rapid pacing of the PM were observed neither in vitro nor in vivo. Atrial and ventricular stimulation thresholds remained unchanged. CONCLUSION: MRI at 0.5 Tesla should not be regarded as absolutely contraindicated in patients with implanted new generation PM. However, knowledge of the behaviour of the specific PM model in static and pulsed magnetic fields is required, if necessary also changes of the PM program prior to the MRI exam, continuous ECG monitoring and cardiological stand-by.

Contraindications↗
PubMed1998

[Spiral CT and MRT of the operated Stanford-type-A aortic dissection: its course and complications].

PURPOSE: To demonstrate normal postoperative spiral CT and MRI findings and typical complications in patients with aortic repair after Stanford type A aortic dissection. METHODS: 24 patients with aortic repair after Stanford type A aortic dissection were followed up by spiral CT and MRI (0.5 Tesla). Presence of persistent dissection, progressive or new dissection, proximal and distal anastomosis, periprosthetic space, supraaortic vessels, thrombosis and dilatation of the true and false lumen were evaluated. RESULTS: The following postoperative complications were seen: three pseudoaneurysms which developed at the proximal anastomoses of the Dacron prosthesis in two cases and at the insertion site of the reimplanted left coronary artery after implantation of a composite graft (Bentall procedure) in one case; one re-dissection; one perforation of the false lumen; periprosthetic flow in one patient after surgical repair of type A dissection by the graft inclusion technique; progressive dilatation of the false lumen in 4 cases; dilatation of the aortic root in a Marfan patient after replacement of the ascending aorta. CONCLUSION: Precise knowledge of the surgical technique performed is crucial to accurate postoperative imaging evaluation. MRI is the method of choice in the postoperative follow-up of clinically stable patients with aortic dissections.

Aortic Dissection↗
PubMed1998

[Detection of focal lung lesions with magnetic resonance tomography using T2-weighted ultrashort turbo-spin-echo-sequence in comparison with spiral computerized tomography].

PURPOSE: To compare spiral CT and MRT for the detection of focal pulmonary lesions. PATIENTS AND METHODS: 50 patients with focal pulmonary lesions confirmed by spiral CT were examined using a T2-weighted UTSE sequence (TE: 90 ms, TR: 1500-3000 ms, echo interval 9 ms, 8 mm slice thickness, diastolic triggering, expiratory breath gating). Image quality was compared using a 4-stage scale. Lesions with a minimum size of 2 mm were counted and measured in the CT image. The results were compared with the MRT images. RESULTS: The image quality in CT examinations with an average value of 1.22 better than that in MRT (1.78). In total 163 pulmonary lesions with a size of 2-115 mm were found by CT. MRT found 151/163 lesions (92.6%). Of the 12 lesions not detected, 9 were smaller than 4 mm, 1 corresponded to a 12 mm large, completely calcified granuloma. In 2 cases there was a 4 or 5 mm large unspecific scar. Thus, 160/163 (98.1%) of all lesions larger than 3 mm were detected. CONCLUSIONS: MRT with use of a suitable UTSE sequence is an alternative to CT for the detection of focal pulmonary lesions with a size larger than 3 mm.

Adolescent↗
PubMed1998

[MRI diagnosis of right ventricular dysplasia].

PURPOSE: Right ventricular dysplasia (RVD) represents an important cause of sudden death and ventricular arrhythmias in young patients. The aim of this study was to describe diagnostic diagnostic criteria and the MR-tomographie aspects of the disease. METHODS: 34 patients with clinically suspected RVD were examined by 0.5-T MRI (cardiac-gated T1-weighted spin echo sequences and cine gradient echo sequences). RVD was confirmed in 16 patients and ruled out in 18 patients. MR images were evaluated for presence of: 1. right myocardial fatty infiltration, 2. dilatation of the right ventricle, 3. dilatation of the right ventricular outflow tract, and 4. localised right ventricular aneurysm. RESULTS: Right myocardial fatty infiltration was detected by MRI in 11 of 16 patients (69%) with RVD. Dilatation of the right ventricle was seen in 5 patients, dilatation of the right outflow tract in one patient, and localised right ventricular aneurysm in two patients with RVD. CONCLUSIONS: MRI is able to demonstrate fatty replacement of right ventricular myocardium in most cases and plays an important role in the diagnosis of RVD.

Adipose Tissue↗
PubMed1998

[MRI in typical and atypical aortic dissection].

PURPOSE: To determine the value of MRI in typical and atypical aortic dissections. METHODS: MRI investigations on 16 patients with aortic dissections were analysed retrospectively; for 8 patients CT investigations carried out at almost the same time were available for comparison. RESULTS: In all cases the diagnosis of aortic dissection was possible from MRI and CT. If a dissection membrane and a double lumen were present these were detected in all patients by both methods. In three patients with atypical dissections, only an asymmetrical abnormal wall thickening as sole sign for the presence of an aortic dissection was seen. A differentiation between true and false lumen was possible in 16 of 17 MRI investigations and in 5 of 8 CT investigations on the basis of differing blood flow velocities or, respectively, the detection of a thrombus in the false lumen. The relationship of the dissection membrane to the large aortic branches as well as the determination of the branch vessel origin with regard to true or false lumen could be evaluated better with MRI than with CT. CONCLUSIONS: Thus MRI has a significant role in the diagnosis and follow-up of aortic dissections. The advantage in comparison to the alternative spiral CT technique is, in addition to the absence of radiation exposure, the better analysis of the extent of the dissection as a result of the multi-planar slice orientation (especially in the region of the aortic arch and the arch vessel origins) without the necessity to administer iodine-containing contrast media.

Adult↗
PubMed1997

Role of Cue1p in ubiquitination and degradation at the ER surface.

Endoplasmic reticulum (ER) degradation of aberrant proteins is mediated by the ubiquitin-proteasome pathway. Here, a membrane-bound component of the ubiquitin system, Cue1p, was identified. It was shown to recruit the soluble ubiquitin-conjugating enzyme Ubc7p to the ER membrane. In the absence of Cue1p, unassembled and thus cytosolically mislocalized Ubc7p was unable to participate in ER degradation or in the turnover of soluble non-ER proteins. Moreover, ubiquitination by Cue1p-assembled Ubc7p and Ubc6p was a prerequisite for retrograde transport of lumenal substrates out of the ER, which suggests that ubiquitination is mechanistically integrated into the ER degradation process.

Amino Acid Sequence↗
PubMed1997

Mutant analysis links the translocon and BiP to retrograde protein transport for ER degradation.

Proteins enter the secretory pathway through the endoplasmic reticulum, which delivers properly folded proteins to their site of action and contains a quality-control system to monitor and prevent abnormal proteins from being delivered. Many of these proteins are degraded by the cytoplasmic proteasome, which requires their retrograde transport to the cytoplasm. Based on a co-immunoprecipitation of major histocompatibility complex (MHC) class I heavy-chain breakdown intermediates with the translocon subunit Sec61p, it was speculated that Sec61p maybe involved in retrograde transport. Here we present functional evidence from genetic studies that Sec61p mediates retrograde transport of a mutated lumenal yeast carboxypeptidase ycsY (CPY*) in vivo. The endoplasmic reticulum lumenal chaperone BiP (Kar2p) and Sec63p, which are also subunits of the import machinery, are involved in export of CPY* to the cytosol. Thus our results demonstrate that retrograde transport of proteins is mediated by a functional translocon. We consider the export of endoplasmic reticulum-localized proteins to the cytosol by the translocon for proteasome degradation to be a general process in eukaryotic cell biology.

Biological Transport↗
PubMed1997

Diagnostic value of MR imaging in comparison to CT in the detection and differential diagnosis of renal masses: ROC analysis.

The aim of this work was to compare MR imaging and CT in the detection of renal masses and in the differential diagnosis between benign and malignant lesions. In 33 patients with 54 renal lesions CT and MR images were evaluated by four readers with regard to tumor detection and characterization using a receiver-operating-characteristics (ROC) analysis. The MRI protocol consisted of a T1-weighted spin-echo (SE) sequence (TR/TE: 300/10 ms) before and after contrast administration and a heavily T2-weighted turbo-SE (TSE) sequence (TR/TE: 5500/150 ms). Az values for the area under the ROC curves for lesion detection were 0.92 +/- 0.04 for CT and 0.91 +/- 0.05 for MRI, respectively, which was not statistically different. The MRI technique was slightly, but not significantly, better than CT in the overall characterization (accuracy in differentiation between benign and malignant) of renal lesions with an Az value of 0.90 +/- 0.05 compared with 0.88 +/- 0.06 for CT. The MRI technique proved to be statistically superior to CT (p < 0.01) in the correct characterization of benign renal lesions. MRI equals CT in the overall detection and differential diagnosis of renal masses. MRI is very helpful for further differential diagnosis of lesions which are equivocal on CT especially in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinoma.

Adult↗
PubMed1997

Indirect MR arthrography: techniques and applications.

Indirect MR arthrography is a simple noninvasive alternative to direct MR arthrography and can potentially alter the diagnostic work-up of several diseases. Based on current knowledge, these diseases include rotator cuff tears. glenoid labrum tears, recurrent tears of the menisci and classification of osteochondritis dissecans. The technique is recommended for inclusion in the MRI diagnostic array, and may obviate the need for invasive direct MR arthrography. The technique and applications of indirect MR arthrography are summarized in this article, based on our own experiences and that described in the current literature.

Adipose Tissue↗
PubMed1997

[The biceps-/rotator cuff-index in ultrasound diagnosis of chronic rupture of the rotator cuff].

PURPOSE: Diagnosis of old lesions of the rotator cuff is clinically and sonographically challenging. To improve the sonographic diagnosis of old rotator cuff tears the index was developed. METHOD: In a prospective study 100 patients were examined by ultrasound to evaluate standard measures of rotator cuff diameters in relation to the long biceps tendon. The compensating hypertrophy of the biceps tendon was sonographically quantified in relation to the rotator cuff diameter. RESULTS: The pathological study group included 50 patients with an old lesion of rotator cuff (> 3 months). The control group consisted of 50 patients without any lesions. Comparison of both groups revealed a significantly higher biceps/rotator cuff ratio (p < 0.05). Data higher than 0.8 represent a pathological ratio (Index positive), the standard is 0.5. The index is independent of sex and age. There are no significant index changes measurable in acute tears of the rotator cuff. CONCLUSION: The index helps to improve sensitivity in diagnosis of old rotator cuff tears by ultrasound.

Adult↗
PubMed1997

[Indirect MR arthrography in the diagnosis of lesions of the labrum glenoidale].

PURPOSE: It has been shown that intravenous administration of contrast media produces an MR arthrographic effect without the need for intraarticular injection. This is the first study evaluating this new technique of indirect MR arthrography in the diagnosis of glenoid labrum tears. METHODS: 28 patients with clinically suspected labral injuries were prospectively investigated (1.5 Tesla, flexible surface coil). A plain MR examination of the shoulder (transverse and oblique-coronal orientation, T1-weighted spin- [TE/TR 15/675], proton density- and T2*-weighted gradient echo [TE/TR/Flip 14,32/600/30 degrees] sequences) and indirect MR arthrography (transverse and oblique-coronal orientation, fat-suppressed T1-weighted spin-echo sequences [TE/TR 15/675], intravenous injection of gadopentetate dimeglumine [0.1 mmol/kg], followed by 10-15 min of joint movement) were performed. Results were confirmed by arthroscopy and/or open surgery. RESULTS: Indirect MR arthrography significantly improved delineation of the glenoid labrum and hyaline cartilage (p < 0.05). Sensitivity and specificity of indirect MR arthrography in the diagnosis of labral injuries were 90% and 89%, compared to 79% and 67% of the native MR examination. CONCLUSION: Indirect MR arthrography is a promising non-invasive technique in the evaluation of the glenoid labrum.

Adult↗
PubMed1997

[MR relaxation time measurements with and without selective fat suppression (SPIR) in endocrine orbitopathy].

PURPOSE: To determine the value and utility of relaxation time measurements with magnetic resonance (MR) imaging in patients with Graves' ophthalmopathy (G.O.). MATERIALS AND METHODS: 20 orbits were studied in control subjects and 58 orbits in patients with G.O. T2 relaxation times of extraocular muscles and retrobulbar fat tissue were calculated. The thickness of the eye muscles was correlated with the calculated T2 times. 18 orbits were measured before and after retro-orbital radiation therapy. RESULTS: Upper limits of determined normal T2 values were 60 ms in extraocular eye muscles and 40 ms in retrobulbar fat tissue. 89% (17/19) of the patients with G.O. had prolonged T2 times in extraocular eye muscles. The retrobulbar fat tissue in 5 of 38 orbits revealed minimal edema with the use of fat saturated sequences. T2 relaxation times decreased significantly (p < 10(-4)) after 10 Gy radiation therapy. No correlation was found between enlargement and T2 relaxation times in extraocular eye muscles (r = 0.44 in patients before radiation therapy). CONCLUSION: In patients with G.O. the determination of the enlargement of extraocular eye muscles in computed tomography is not a sufficient parameter for an antiinflammatory therapy, since CT cannot visualise eye muscle edema. T2 relaxation time measurements with MR imaging allow differentiation between edematous and fibrotic changes. This is the diagnostic method of choice in patients with Graves' ophthalmopathy.

Adipose Tissue↗
PubMed1997

[Craniocervical dissections: study strategies in MR imaging and MR angiography].

PURPOSE: To define the diagnostic efficacy of MR imaging, "time of flight" (TOF) and phase contrast (PC) MR angiography in craniocervical arterial dissections. MATERIAL AND METHODS: The MR examinations of 16 patients with proven arterial dissections (n = 20) were retrospectively analysed by three independent readers. The MR protocol included T1w spin echo sequences with and without fat saturation (SPIR), T2w-turbo-spin echo, 2D- and 3D-TOF- and 3D-PC-MRA. The study was undertaken to assess the diagnostic sensitivity of each technique in detecting typical pathological features. RESULTS: The overall sensitivity was best in 3D-PC-MRA; reaching 88% of all possible points. Intramural haematoma could be easily detected with T1W spin echo with fat saturation (100%). Intimal flap and lumen narrowing was best defined with 3D-TOF-MRA in 86% resp. 96% and 3D-PC-MRA in 69% resp. 97%. 3D-PC-MRA was superior to all other sequences in 5 cases of aneurysmal dissection (100%). CONCLUSIONS: An accurate evaluation of craniocervical arterial dissections should rely on a combined protocol including T1w spin echo with fat saturation and an axial 3D-MR angiography (if possible 3D-phase contrast MRA).

Adolescent↗
PubMed1997

[Perfusion manometry in the evaluation of postoperative swallowing function following various reconstructive procedures of the upper aero-digestive tract].

BACKGROUND: The swallowing function can be restored after large oncologic resections in the upper aerodigestive tract with microvascular anastomosed transplants. PATIENTS AND METHODS: With the help of the perfusion manometry we would like to demonstrate the functional advantages of this reconstruction method. We examined three reconstructed regions: tongue with 15 patients, soft palate with 11 patients, and the laryngeal and pharyngeal complex after total laryngopharyngectomy with 17 patients. RESULTS: Patients with reconstructed tongue or soft palate reached 69% or 74% of their pressure compared to normal values. CONCLUSIONS: We demonstrated that although normal pressure values were not reached after reconstruction of large defects with microvascular anastomosed transplants; these reconstruction methods restored the pressure gradient essential for swallowing, with a higher pressure of the soft palate and a lower pressure of the base of tongue.

Deglutition↗
PubMed1997

[Significance of p53, PCNA and Ki-67 in the prognosis of squamous cell carcinoma of the oral cavity].

BACKGROUND: A common gene alteration in human malignancies is the mutation of the p53 gene. Through mutation p53 loses its function as a tumor suppressor and enables the tumor to proliferate. Ki-67 and PCNA are proliferation markers. The aim of this study was to find a reference to the prognostic significance of p53, Ki-67, and PCNA in squamous cell carcinoma (SCC) of the oral cavity. MATERIAL AND METHODS: Samples from 64 patients of the Department of Otolaryngology/Head and Neck Surgery, University of Bergen, Norway, with histologically proven SCC of the oral cavity were submitted to immunohistochemical procedure. All carcinomas were untreated. RESULTS: 59.3% of the patients showed a positive reaction for p53.Ki-67 and PCNA were expressed in about 68% of the cases, but with less staining intensity. No correlation could be found between the expression of the three antibodies and tumor factors such as tumor size, lymph nodes, degree of differentiation, recurrence and survival rate, the occurrence of second primaries, or the smoking habits of the patient. CONCLUSIONS: The expression of the tumor suppressor gene p53 and the proliferation marker PCNA and Ki-67 seem to have no prognostic significance in SCC of the oral cavity.

Adult↗
PubMed1997

The Srp40 protein plays a dose-sensitive role in preribosome assembly or transport and depends on its carboxy-terminal domain for proper localization to the yeast nucleoskeleton.

The yeast SRP40 gene product (Srp40p) is a highly serine-rich protein organized in three distinct domains. The roles of these domains in localizing Srp40p were determined. By indirect immunofluorescence microscopy, Srp40p localizes to punctate, sometimes fibrillar, subnuclear structures that might include the nucleolus. Its amino-terminal and medial domains are similar. They each start with a short basic stretch containing a nuclear localization signal, followed by a long acidic stretch with 76% serines; such acidic stretches are thought to mediate binding to ribosomal proteins in the nucleolus. Either domain is sufficient to determine nuclear localization of Srp40p. The Srp40p carboxy-terminal domain shows significant homology to the cognate domain of Nopp140, a mammalian nucleolar phosphoprotein of 140 kD. The carboxy-terminal domain alone, or fused to a reporter protein, displays a punctate localization outside the nucleus. Srp40p and Nopp140 share a highly homologous 39-residue motif within their similar carboxy-terminal domains. Inside or outside the nucleus, this motif is important to prevent Srp40p diffusion or degradation. These observations suggest that the punctate immunoreactive structure is nucleoskeletal and might result from Srp40p self-assembly. SRP40 genetically interacts with four mutants affected in stable RNA synthesis and one mutant blocked in protein translocation to the endoplasmic reticulum. Growth defects, but no translocation or rRNA transcription/maturation phenotypes, were observed upon SRP40 inactivation or strong overexpression. Together, these data point to a dispensable, dosage-sensitive, role of Srp40p in preribosome assembly or transport.

Amino Acid Sequence↗