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Biomedical subjects

U Müller-Lisse

Publications and source records attributed to U Müller-Lisse.

15 recordsLinked to original sources
PubMed2006

[Alternative sonographic determination of liver size by intercostal scans].

BACKGROUND: The evaluation of hepatic size is a daily question in abdominal ultrasound, especially to determine the presence of hepatomegaly. In the literature, different methods of measurement are described, mostly as a subcostal measured organ diameter in one direction. This method has its limits in patients with obesity, accumulation of abdominal gas or in uncooperative patients (lack of coordinative respiration) so that alternative measurements are necessary. METHODS: In 241 patients hepatic size was first measured in two conventional sections: midclavicular line (MCL) and anterior axillary line (AAL). Additionally, we measured the organs in midaxillary line craniocaudal (MAL) by determination of the cranio-caudal diameter. In 58 patients additional computed tomography was performed due to special diagnostical reasons so that liver size in MCL could be revealed and compared with ultrasonographical values. RESULTS: The mean value in MCL was 10.7 +/- 2.1 cm measured by ultrasound, 11.4 +/- 3.7 cm measured by computed tomography, 14.0 +/- 1.9 cm in AAL and 14.9 +/- 2.0 cm in MAL. In 5% of the cases the liver could not be measured in the conventional subcostal sections due to obesity or masking by gas, but this was possible in MAL. CONCLUSIONS: We revealed a good correlation of liver size in MCL between ultrasound and computed tomography, as well as in the measurement of AAL and MAL diameters. However, even in cases with difficult subcostal approach intercostal diameters allow for an accurate determination of hepatic size.

Adult↗
PubMed2003

[Urological emergencies].

Urological emergencies that require specialist treatment include testicular torsion, gross hematuria, urogenital injuries and acute flank pain. After initial symptoms-adapted therapy, patients should be transferred immediately to an urological department for imaging (e.g. ultrasound, IVP, CT) and further specific examinations (e.g.blood tests, urine analysis, microbiology). Acute lower abdominal and scrotal pain in young men may be symptomatic of testicular torsion, which requires immediate urological surgery. Gross hematuria is usually not a life-threatening emergency. Nevertheless, urogenital tumor has to be ruled out by an urologist. Patients with urogenital injuries are triaged into surgical and non-surgical treatments. Differential diagnosis of acute flank pain falls into several medical fields. After initial symptom-related therapy, further diagnostic procedures have to be performed. Septic presentation may be symptomatic of infectious hydronephrosis which requires immediate urological intervention.

Diagnosis, Differential↗
PubMed1998

Non-invasive temperature mapping using MRI: comparison of two methods based on chemical shift and T1-relaxation.

PURPOSE: To implement and evaluate the accuracy of non-invasive temperature mapping using MRI methods based on the chemical shift (CS) and T1 relaxation in media of various heterogeneity during focal (laser) and external thermal energy deposition. MATERIALS AND METHODS: All measurements were performed on a 1.5 T superconducting clinical scanner using the temperature dependence of the water proton chemical shift and the T1 relaxation time. Homogeneous gel and heterogeneous muscle phantoms were heated focally with a fiberoptic laser probe and externally of varying degree ex vivo by water circulating in a temperature range of 20-50 degrees C. Magnetic resonance imaging data were compared to simultaneously recorded fiberoptic temperature readings. RESULTS: Both methods provided accurate results in homogeneous media (turkey) with better accuracy for the chemical shift method (CS:+/-1.5 degrees C, T1:+/-2.0 degrees C). In gel, the accuracy with the CS method was +/-0.6 degrees C. The accuracy decreased in heterogeneous media containing fat (T1:+/-3.5 degrees C, CS: +5 degrees C). In focal heating of turkey muscle, the accuracy was within 1.5 degrees C with the T1 method. CONCLUSION: Temperature monitoring with the chemical shift provides better results in homogeneous media containing no fat. In fat tissue, the temperature calculation proved to be difficult.

Animals↗
PubMed1997

Spiral CT angiography and 3D reconstruction in patients with aortic coarctation.

The objective of this study was to assess the reliability of spiral CT angiography (CTA) and 3D reconstruction in patients with aortic coarctation (CoA). Eighteen patients with suspected or surgically proven coarctation were examined by spiral CT. In addition to the axial slices, 3D reconstructions, such as shaded surface display (SSD) and maximum intensity projection (MIP), were used to determine the diameters of the CoA and the pre- and poststenotic aorta and to visualise the collateral vessels. Diameters derived from cardiac catheterization were compared with those from CTA in 8 patients. The degree of aortic stenosis was correlated with blood pressure gradients (BPG) in 12 patients. The difference between the diameters of the CoA and the pre- and poststenotic aorta derived from MIP and angiography was not statistically significant (p = 0.69). With SSD the internal thoracic artery was detected in 16 and the posterior intercostal artery in 13 cases. The degree of aortic stenosis correlated poorly with the BPG (r = 0.51, r2 = 0.26). CTA with 3D reconstruction represents a reliable noninvasive technique for the assessment of the degree of CoA and the visualisation of collateral vessels. It may serve as a follow-up investigation after intervention or surgical treatment.

Adolescent↗
PubMed1997

[Lymph node staging in cervix carcinomas: the results of high-resolution magnetic resonance tomography (MRT) with a phased-array body coil].

PURPOSE: To determine the diagnostic value of high resolution MR imaging with a circularly polarised (c.p.) body phased-array coil for the staging of pelvic lymph nodes in cervical carcinoma. MATERIAL AND METHODS: 42 patients with histologically proven carcinoma of the cervix were studied on a 1.5 T scanner by using a c.p. body phased-array coil. The imaging protocol included T2-weighted turbo-spin-echo (TSE) and T1-weighted spin-echo sequences pre and post i.v. application of Gd-DTPA; slice thickness was 5-7 mm and pixel size 0.53 mm2. Lymph nodes with a diameter of > or = 8 mm were considered to have metastatic involvement. MR imaging results were compared with histopathologic findings. RESULTS: MR imaging showed enlarged lymph nodes (> or = 8 mm) in 16 of 18 patients with histologic proof of lymph node metastases (sensitivity 89%). In 22 of 24 cases MR findings were true negative (specificity 92%). Diagnostic accuracy was 91%. CONCLUSION: High-resolution MR imaging with a c.p. body phased-array coil provides high sensitivity, specificity, and diagnostic accuracy for pelvic lymph node staging in cervical carcinoma.

Adult↗
PubMed1997

[Parametrial infiltration of cervix carcinoma: diagnostic value of contrast-enhanced fat-suppressed T1-weighted SE sequences at 1.5 tesla].

PURPOSE: To determine whether contrast-enhanced and fat-suppressed sequences contribute to the MR imaging diagnosis of parametrial invasion. METHODS: 21 patients with carcinoma of the cervix were prospectively examined with a phased-array coil and a 1.5T MR-scanner using the following sequences: transverse T2-weighted turbo spin echo (T2-TSE), T1-weighted spin echo (T1-SE) and fat suppressed T1-weighted SE sequences before and after Gd-DTPA. The sequences were evaluated separately for the presence of parametrial invasion. Image quality and diagnostic confidence were classified on a scale of 0-10 (nondiagnostic-excellent). Findings were compared to the results of the pathohistological examination. RESULTS: Sensitivity, specificity and diagnostic accuracy were highest for T2-TSE sequences (100%, 79% and 86%, respectively). Contrast-enhanced T1-SE sequences with fat-suppression (71%, 79%, and 76%) showed no improvement compared to T2-TSE. Unenhanced fat-suppressed T1-SE (100%, 30%, and 56%) and unenhanced T1-SE (100%, 7%, and 38%) as well as contrast-enhanced T1-SE (86%, 20%, and 47%) were significantly worse than T2-TSE. With similar image quality (p < 0.05) diagnostic confidence was higher on T2-TSE than on any of the other sequences (p < 0.001). CONCLUSION: Considering the cost-effectiveness of the examination, for the MR diagnosis of parametrial invasion the use of fat-suppressed contrast-enhanced sequences can be abandoned in favour of T2-weighted TSE sequences.

Adult↗
PubMed1996

[Technics for the preoperative marking of nonpalpable breast lesions in MRT].

We describe a method of localizing suspicious breast lesions only visible by MRI that does not require additional hardware and can be carried out on any MRI-scanner suited for MR-mammography. We have performed a total of 48 localizations with different techniques: 28 charcoal/Gd-DTPA, 18 with wires and two skin markings. All localizations have been successful; wire localizations provided the best results, since the position of the wire could be corrected under MR-guidance. Until suitable localization- and biopsy coils become available the methods employed by us provide a satisfactory alternative which allows radiologists who perform diagnostic MR-mammography with techniques to carry out precise pre-operative localisations of breast lesions.

Breast↗
PubMed1995

[The facial nerve in the petrous bone in thin-layer paratransverse and sagittal magnetic-resonance-tomographic T1-spin-echo and FLASH images].

PURPOSE: It is difficult to effect visualization and delineation of the facial nerve and its neighbouring structures in the temporal bone with conventional MRI examination protocols. We tested temporal bone MRI with 2 mm slices and compared T1-weighted FLASH (TR = 400 ms, TE = 10 ms, 90 degrees flip angle) and spin-echo (TR = 540 ms, TE = 15 ms) sequences. PATIENT AND METHODS: 5 volunteers and 14 patients were examined with the head coil of a 1.0T whole body MRI scanner (Impact, Siemens, Erlangen) with para-transversal images orientated parallel to the inferior outline of the clivus and sagittal images orientated along the brainstem. RESULTS: The facial nerve and its neighbouring structures could be reliably visualized and differentiated along its entire course. The FLASH sequence was superior to the spin-echo sequence. 8 of 11 patients with peripheral facial nerve palsy showed contrast enhancement. In two patients, local swelling of the affected facial nerve was evident. CONCLUSION: The MRI technique tested here seems promising for temporal bone examinations.

Adult↗
PubMed1995

[Vascular, inflammatory and tumorous lesions of the temporal bone and cerebellopontile angle: applications of magnetic resonance tomography].

Advances in high resolution magnetic resonance imaging (MRI) allow the evaluation of the cerebellopontine angle and temporal bone. The purpose of our study was to demonstrate pathological and anatomical aberrations of cerebral arteries in relation to clinical symptoms. The study was carried out on a 1T MR whole body scanner (Impact, Siemens, Erlangen, Germany), using a head coil, a pre- and postcontrast ("Magnevist", Schering, Berlin, Germany) T1-weighted 2D-FLASH sequence and a T2-weighted turbo-spin echo sequence. We examined 22 patients suffering from asymmetric hearing loss, pulse-synchronous tinnitus, hemifacial spasm or facial palsy. The problem of a clear differentiation of meningiomas and acoustic neurinomas by means of MRI is discussed. We identified aberrant AICAs at the cerebellopontine angle in close contact with the V., VII. and VIII. cranial nerve. Inflammatory lesions of the facial and vestibulocochlear nerve were visualised successfully. The potential of the pre- and postcontrast 2D-FLASH sequence for the detection of a wide range of different lesions in the cerebellopontine angle and the temporal bone in MRI of the head was demonstrated.

Arteries↗
PubMed1995

[Phased-array superficial coil and breath holding technique in MRI of the liver. Comparison of conventional spin echo sequences with rapid fat suppressing gradient echo and turbo-spin sequences].

PURPOSE: To determine the efficacy of fast MRI techniques using a tailored imaging design (breathhold and array-surface coil), conventional T1-, T2-weighted spin-echo (SE) sequences and breathhold gradient-echo (GRE) T1- and breathhold fast SE T2-weighted images were compared. METHODS: 20 patients with proven focal liver lesions were studied on a 1.5 Tesla system. Conventional SE T1- and T2-weighted imaging, as well as GRE T1- and fast SE T2-weighted imaging was performed. Fast imaging was done during breathhold using an array-surface coil. For all sequences signal-to-noise ratios (S/N) and liver-to-lesion-contrast ratios (L/L) were measured and statistically compared. In addition, two blinded readers qualitatively evaluated all images, using a score system regarding artifacts (breathing, pulsation), number of lesions, and over-all image quality. RESULTS: Regarding image quality parameters, S/N and L/L, there was no significant (p > 0.05) difference between the conventional and fast imaging techniques. However, GRE imaging was superior (84.8%) to conventional imaging for breathing and pulsation artifacts, while fast SE T2 imaging was equal regarding breathing artifacts, but superior (51.5%) regarding pulsation artifacts. The number of detected hepatic lesions was identical in all sequences. CONCLUSION: The fast MRI techniques demonstrated a superiority to conventional imaging regarding image quality and presence of artifacts. Therefore, fast imaging techniques can replace conventional techniques, at least in patients that can sufficiently sustain breathing.

Artifacts↗
PubMed1995

[Fast and ultra-fast sequences in MRI of the pelvis and retroperitoneum].

Fast and ultrafast sequences are crucial prerequisite for optimum diagnostic impact in magnetic resonance (MR) imaging of the pelvis and retroperitoneum. In MR imaging of the pelvis, heavily T2-weighted fast turbo spin echo (TSE) sequences with acquisition times of 2-4 min have widely replaced time-consuming conventional T2-weighted SE sequences due to substantial time savings and better image quality. Fast and ultrafast gradient recalled echo (GRE) sequences are the basis of dynamic contrast-enhanced studies. In MR imaging of the retroperitoneum, fast and ultrafast sequences currently play the most important role as they allow for breath-hold acquisition of a sufficient number of images free of motion artifacts. The current roles of TSE, tubo gradient spin echo (TGSE), GRE and echoplanar imaging (EPI) sequences in MR imaging of the pelvis and retroperitoneum is discussed.

Artifacts↗
PubMed1994

[High resolution magnetic resonance tomography of the temporal bone].

Computed tomography (CT) has long been the method of choice for investigations of the temporal bone. Advances in high resolution magnetic resonance imaging (MRI) enabled MRI of the temporal bone. The purpose of this study was to assess detailed reconstruction of the anatomy of the temporal bone by MRI. Healthy volunteers were examined on a 1T MR whole body scanner (Impact, Siemens, Erlangen, Germany). A Helmholtz-configurated head coil was used. A T1-weighted 2D-FLASH sequence (TR = 400 ms, TE = 10 ms, 90 degrees flip angle, 2 mm slice thickness, 180* 256 matrix, 160 mm FOV) was performed pre- and postcontrast as well as a T2-weighted turbo spin echo sequence (TR = 6300 ms, TE = 112 ms, 3 mm slice thickness, 200 mm matrix, 200 mm FOV). A sagittal and an angulated paraxial projection, parallel to the nasopharyngeal edge of the clivus, were chosen. We suceeded in imaging the facial nerve along its entire course, including the geniculate ganglion and the greater superficial petrosal nerve, the cochlear nerve and the vestibular nerve (superior and inferior part). The facial nerve was visualised continuously from the cerebellopontine angle to the foramen stylomastoideum. The delineation of the different turns of the cochlea, the vestibule and the semicircular canals was excellent. High resolution MRI promises to be of great value in the diagnosis of the temporal bone.

Cochlea↗
PubMed1993

["Spectroscopic imaging." A new MR technique in the diagnosis of epilepsy?].

The technique of magnetic resonance spectroscopy fuses spectroscopic methods with the two-dimensional illustration of the metabolite concentrations by parallel acquisition of multiple single voxels from small tissue compartments. Therefore it is not necessary to define a voxel of interest before data acquisition. The interpretation of metabolite images is much easier than the analysis of single spectra, and metabolite concentrations on the right and left sides can be compared. The method has already proved reliable for brain tumors. The application of the procedure to patients suffering from epilepsy is described here in for the first time. Even in the temporal region, where most epileptogenic foci have their origin, one can obtain metabolite images of diagnostic quality without susceptibility artifacts. The epileptogenic focus is lateralized correctly, in accordance with electrophysiological and surgical evaluation, even in those cases where standard magnetic resonance imaging is normal. According to our preliminary findings the epileptogenic focus is characterized by a signal loss of N-acetyl-aspartate and creatine.

Adult↗
PubMedDate not supplied

High resolution Gd-DTPA MR imaging of the inner ear in 60 patients with idiopathic vestibular neuritis: no evidence for contrast enhancement of the labyrinth or vestibular nerve.

Sixty patients with acute idiopathic vestibular neuritis (confirmed by clinical examination and caloric irrigation) were evaluated in a prospective study by high resolution magnetic resonance imaging (hr-MRI) between days 3 and 30 after onset of symptoms. We used a 1.5 Tesla imager with an axial and coronal T1-weighted 2D-fast low angle shot-, T2-weighted turbo spin echo-, and an axial T2-weighted 3D-constructive interference in steady-state sequence for MRI. None of the patients' MRIs exhibited contrast enhancement of the labyrinth, vestibulocochlear nerve, or vestibular ganglion, even when high doses of gadolinium (0.2 mmol/kg) were used. In contrast, several previous studies demonstrated contrast enhancement of the vestibulocochlear nerve/labyrinth in herpes zoster oticus, labyrinthitis, and Cogan's syndrome or of the facial nerve in Bell's palsy. On the basis of our MRI findings, we speculate that idiopathic vestibular neuritis is neither a viral infection directly affecting the nerve (such as herpes zoster) nor a labyrinthitis. An autoimmunological disease of the labyrinth, which should involve only the anterior and horizontal semicircular canals, is also unlikely. A subacute reactivation of a latent viral infection--as discussed for Bell's palsy--is compatible with our MRI findings. The observed differences between contrast enhancement of the facial nerve in Bell's palsy and the vestibulocochlear nerve in vestibular neuritis may be due to their dissimilar anatomy: contrary to the vestibular nerve, the facial nerve has very prominent circumneural arteriovenous structures. Hyperemia within these vascular structures may cause the contrast enhancement seen in Bell's palsy.

Acute Disease↗