Biomedical subjects

M Müller-Schimpfle

Publications and source records attributed to M Müller-Schimpfle.

14 recordsLinked to original sources

PubMed1998

Gd-enhanced 3D phase-contrast MR angiography and dynamic perfusion imaging in the diagnosis of renal artery stenosis.

The objective of this study was to investigate the role of contrast enhancement using a three-dimensional (3D) phase-contrast (PC) magnetic resonance (MR) sequence (3D PC-MRA) and to assess the value of a dynamic MR perfusion study of the kidneys to determine the hemodynamic relevance of unilateral renal artery stenosis (RAS). Seventeen patients with unilateral RAS were examined on a standard 1.0 T imaging system using a phase shift and magnitude sensitive 3D PC sequence (TR=160 ms, TE=9 ms, venc. 30 cm/s). Following the initial pre-contrast 3D PC-MRA a dynamic first pass perfusion study was performed using a Turbo-FLASH 2D sequence (TR=4.5 ms, TE=2.2 ms, TI=400 ms) after bolus injection of 0.15 mmol gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)/kg body weight. The 3D PC-MRA was then repeated during infusion of 0.15 mmol Gd-DTPA/kg body weight. Evaluation by three independent readers was based on maximum intensity projection images. Source images were rendered on request. Signal intensity (SI) over time curves of the renal cortex were obtained from the dynamic perfusion study and analyzed for maximum signal enhancement as well as temporal relationship to the aortic SI curve. Results from 3D PC-MRA revealed a sensitivity (pre-/post-contrast) of 100%/89%, specificity of 76%/63%, positive predictive value of 80%/69 %, negative predictive value of 90%/78%, and accuracy of 85%/75% (p=0.07). Interobserver agreement was kappa=0.61/kappa=0.47 (pre/post Gd-DTPA), respectively. Increased signal-to-noise was present in all segments of the renal arteries post contrast (p=0.0003). This came along with image degradation due to aliasing and elevated SI of venous flow that partially obscured the renal arteries. Dynamic SI curves showed a significantly decreased maximum SI in RAS (p=0.01-0.001). A temporal delay of cortical signal intensity enhancement could not be confirmed in this setting. Gd-enhanced 3D PC-MRA did not yield a superior diagnostic value in the diagnosis of RAS compared to pre-contrast measurements. Dynamic perfusion imaging of the kidneys, in combination with 3D PC-MRA, can contribute additional information in suspected unilateral RAS.

Aged↗

PubMed1998

[Precise MR-guided preoperative marking of breast lesions with an embolization coil using a standard MR coil].

PURPOSE: To develop and test a new technique for MR-guided localisation of breast lesions. MATERIALS AND METHODS: The examinations were performed on a 1.0 T imager in prone position, using a sagittally oriented oval spine coil. The localization device consisted of a perforated lateral plate which can be angulated. The plate contained an "M" shaped tube filled with oil. This enabled exact localization of the lesion in relation to the bore holes on the MR images. After needle placement through a sterile bushing, the 5 mm marking coil was placed through the needle adjacent to the lesion. Then a suspension of charcoal, Gd-DTPA, and water was injected. Suspicious lesions that could be visualised only by MR were localised preoperatively and marked in 6 patients. RESULTS: The lesion size ranged from 0.5 to 3.5 cm (median 1.2 cm). Three benign lesions (intraductal hyperplasia twice, radial scar once) and three malignant lesions (ductal invasive cancer twice, DCIS once) were found. Angulation of the plate was beneficial in three cases. CONCLUSION: With the new marking technique, exact MR-guided localization of breast lesions using an add-on device is feasible. Construction of an additional MR coil is not necessary. Excision of the lesion is proven by the concomitant excision of the marking coil.

Anesthesia, Local↗

PubMed1997

[Effect of age and menstrual cycle on mammography and MR mammography].

Age and menstrual cycle have an important influence on the breast. This well-known fact is experienced in the daily routine of gynecologists and radiologists. The number of publications addressing the effect of these influences on imaging, however, is surprisingly low. The aim of this work is to describe the influences of age and menstrual cycle on the breast and to address their clinical relevance for mammography and MR mammography. Therefore, own data are presented concerning the age and menstrual cycle influences on breast parenchyma in dynamic MR mammography. Literature data are used to correlate mammography and MR imaging findings with these influences. The changes of the breast due to age and menstrual cycle have important direct implications on performing and reading conventional mammography and MR mammography. The knowledge of these changes is also helpful in the interpretation of findings when comparing different methods. Finally, the data gained by using imaging methods enable important basic insights into physiology and physiopathology of the breast in vivo.

Adolescent↗

PubMed1997

[Mammography and mammary ultrasonography: which examination sequence is preferable?].

PURPOSE: To compare primary mammography diagnosis (ultrasound report available) with primary ultrasound diagnosis (mammography report available). METHODS: 89 preoperative patients with suspicious lesions were included. Mammography and ultrasound of all patients were evaluated by two independent experienced readers under clinical conditions. The reports of the complementary modality were available to both observers. Lesion evaluation was done on a per breast basis, in cases of multiple lesions in respect of the lesion with the greatest risk of malignancy. RESULTS: 39 benign and 59 malignant lesions were found. Primary mammography and primary ultrasound yielded 3 and 8 false positives and 10 and 13 false negatives. Concerning the palpable lesions (n = 59), primary mammography and primary ultrasound had no and 4 false positives and 7 and 8 false negatives, respectively, for the non palpable lesions, the figures were 3 and 4 false positive and 3 and 5 false negatives. CONCLUSIONS: Mammography remains the method of first choice in early detection of breast cancer, whereas breast ultrasound should be performed after and in knowledge of the mammogram, in consideration of the known indications (equivocal palpable lesion and mammographic opacity, dense breast).

Adolescent↗

PubMed1997

Phase-contrast MR angiography for detection of arteriosclerotic renal artery stenosis.

PURPOSE: To compare the accuracy of 3-D phase-contrast (PC) MR imaging with a 2-D time-of-flight (TOF) technique in the detection of arteriosclerotic renal artery stenosis. MATERIAL AND METHODS: Twenty-two patients with 28 angiographically proven renal artery stenoses were examined in a prospective blinded fashion by using 2-D TOF MR angiography (MRA) with venous saturation (FLASH) and 3-D PC MRA. The renal arteries were subdivided into 3 segments and graded for the presence of stenoses on a scale of 0-4 by 3 radiologists in blind. RESULTS: The accuracy of TOF and PC imaging in detecting renal artery stenoses was 65% and 77% respectively. Both 2-D TOF and 3-D PC MRA depicted 84% of the stenoses of the proximal renal artery greater than 50% in diameter. Renal artery stenoses greater than 50% and more than 15 mm in distance from the aorta were detected in 40% of cases with the 2-D TOF sequence and in 76% with the 3-D PC technique (p < 0.05). The rate of false-negative results was 32%. CONCLUSION: PC MRA is better at visualizing stenoses in the middle segment of the renal arteries and supplements conventional TOF techniques with additional information. However, even when the two techniques are combined, the false-negative rate in the MR imaging of stenoses of the renal arteries still needs to be reduced.

Aged↗

PubMed1997

Menstrual cycle and age: influence on parenchymal contrast medium enhancement in MR imaging of the breast.

PURPOSE: To evaluate the influence of menstrual cycle and age on parenchymal contrast medium enhancement in magnetic resonance (MR) imaging of the breast. MATERIALS AND METHODS: Dynamic gadolinium-enhanced fast low-angle shot, three-dimensional breast MR imaging was performed with high temporal and spatial resolution (eight measurements in 10 minutes). Menstrual cycle evaluations and age-influence studies were performed in 44 patients aged 27-55 years with a regular cycle (mean age, 41.5 years) and in 103 patients aged 15-79 years (mean age, 49.3 years), respectively. A region of interest was placed in each quadrant of the breast for evaluation of parenchymal enhancement. Quadrants with complete involution or lesions and patients who received hormonal therapy were excluded [corrected]. Analysis of variance was performed. RESULTS: Parenchymal contrast medium enhancement in cycle days 7-20 (geometric mean enhancement at minutes 1-10 = 0.12-0.47) was significantly lower than that in cycle days 21-6 (geometric mean, 0.17-0.98; P < or = .001). Contrast medium enhancement in patients aged 35-50 years (mean enhancement, 0.17-0.75) was significantly higher than that in patients aged younger than 35 years or older than 50 years (mean enhancement, 0.12-0.40; P < .01). CONCLUSION: Patients showed statistically significantly lower parenchymal enhancement in menstrual cycle days 7-20 than in days 21-6. Patients aged 35-50 years yielded higher parenchymal enhancement than did younger patients and older patients.

Adolescent↗

PubMed1997

Do mammography, sonography, and MR mammography have a diagnostic benefit compared with mammography and sonography?

OBJECTIVE: The purpose of our study was to assess the added value of MR mammography, mammography, and sonography compared with mammography and sonography in diagnostic evaluation of the breast. MATERIALS AND METHODS: We evaluated reports of MR mammography, conventional mammography, and sonography of the breast in 89 patients who had been referred for surgical biopsy. The dynamic MR mammography examinations were obtained on a 1.0-T MR imager using a double-breast coil and a three-dimensional axial fast low-angle shot sequence. Each type of study was interpreted by a different observer. All mammograms and sonograms were available to all observers. Without knowledge of biopsy results, observers classified mammograms and sonograms (which we call the standard method) as well as mammograms, sonograms, and MR mammograms (which we call the combined method). Classifications were on a per-breast basis: no disease; probably a benign or malignant lesion; and most likely a benign or malignant lesion. A classification of no disease or most likely a benign or malignant lesion was considered to represent a high confidence of the observer in the diagnosis. RESULTS: Of 98 breasts evaluated with the standard method, observer confidence was high for 44% of all malignant lesions versus 86% with the combined method. The highest specificity (92%) was achieved by interpretation of the standard method (combined method, 64%). The highest sensitivity (95%) was achieved by interpretation of the combined method (standard method, 83%). Overall accuracy was 87% for the standard method and 83% for the combined method. In separate analyses of nonpalpable and palpable lesions, the combined method achieved an accuracy of 74% for nonpalpable lesions and 88% for palpable lesions. The standard method achieved an accuracy of 85% for nonpalpable lesions and 88% for palpable lesions. CONCLUSION: MR mammography as an adjunct to mammography and sonography reveals breast cancer with a higher confidence and sensitivity than do mammography and sonography only. The combined method can be recommended if the greatest possible sensitivity or negative predictive value is wanted. However, the combined method is not useful for screening or workup of suspicious lesions because of its lower specificity and accuracy.

Breast↗

PubMed1995

[Dynamic 3D MR mammography using a rapid gradient-echo sequence].

Up to now, MR mammography is performed by two different methods: 2-D techniques with high temporal resolution and 3-D techniques with high spatial resolution. This article investigates whether a dynamic examination of the breast using a novel 3-D-gradient-echo sequence is feasible with sufficient spatial and temporal resolution. MR imaging was performed on a 1.0 Tesla imager using a gradient field strength of 15 mT/m. Phantom measurements were done to evaluate the correlation between signal intensity and contrast medium concentration for different sequences. Subsequently, 40 patients with 22 histologically verified lesions were examined using the double breast coil and a novel FLASH3D sequence (TR/TE/fa 9/3/50 degrees). Reading of the films in standardized documentation, multiplanar reconstruction (MPR), calculation and maximum intensity projection (MIP) of subtraction images as well as signal-to-time curve calculations in selected ROIs were performed for data evaluation. In the phantom measurements the FLASH3D-9/3/50 degrees sequence yielded the best correlation between signal intensity and Gd-DTPA concentration. The sequence provided good visualization even of small lesions. The 3-D postprocessing procedures facilitated the detection and localization of the lesions. Therefore, the new FLASH3D-9/3/50 degrees sequence enables a dynamic 3-D examination of the breast with a sufficient spatial and temporal resolution.

Adolescent↗

PubMed1995

[High-resolution magnetic resonance tomography of the anal sphincter using an intravaginal surface coil].

PURPOSE: To assess the visualisation of the anal sphincter by means of an intravaginal surface coil. METHODS: MR imaging was performed using a 1.0 T unit. In 10 females (6 nullipara, one primipara without and three primipara with postpartum faecal incontinence) a surface coil, originally designed for endorectal use, was placed into the vagina. Transverse oblique T1-weighted spin echo and double echo turbo spin echo sequences with T2- and proton density-weighting were acquired parallel to the puborectal, rectococcygeal and anorectal planes. Three readers analysed the images in consensus. RESULTS: The anatomic structures of the external and internal sphincter as well as the mucosa were differentiated in all cases with a good contrast. The best results were yielded by the proton density weighting. In one case of faecal incontinence a sphincter defect after repair of a complete rupture of the anal sphincter was shown. In another case irregularities in the structure of the external sphincter and perineum were visualised. CONCLUSION: Intravaginal surface coil imaging seems a well-tolerated novel method for the evaluation of the anal sphincter tissues in truly anatomical states. Due to its capability to depict subtle tissue structures as well as pathologic irregularities, it might become a potential tool in the diagnosis and operation planning of postpartal faecal incontinence.

Adult↗

PubMed1993

Recurrent rectal cancer: diagnosis with dynamic MR imaging.

PURPOSE: To evaluate whether dynamic magnetic resonance (MR) imaging can increase the diagnostic accuracy in suspected local recurrence of rectal carcinoma. MATERIALS AND METHODS: Eighteen patients (seven men, 11 women, aged 26-78 years) with 19 suspect lesions were examined. T1-weighted (pre- and postcontrast) and T2-weighted spin-echo images were read by three observers. Computed tissue-specific enhancement parameters were obtained and displayed on gray-scale images (pharmacokinetic mapping). RESULTS: Reading of the spin-echo images yielded a sensitivity of 91%-100% (confidence interval, 67%, 100%), a specificity of 29%-43% (12%, 67%), and an accuracy of 71%-75% (48%, 91%). Analysis of the MR data showed greater (P = .0038) and faster (P = .0018) enhancement of malignant lesions (n = 12) compared with benign lesions (n = 7). CONCLUSION: Pharmacokinetic mapping of dynamic MR imaging data allows in vivo insight into tissue physiopathology, helping differentiate benign from malignant pelvic lesions in rectal cancer.

Adult↗

PubMed1992

[MR tomography and MR angiography--a new method for the planning of the irradiation of large abdominal fields].

Subdiaphragmatic radiation therapy in malignant lymphoma requires complete irradiation of retroperitoneal lymph nodes, spleen and splenic pedicle and optimal shielding of radiosensitive structures. The aim of our study was to develop a new method for individual field definition by using MR tomography and MR angiography. In 38 patients with malignant lymphoma coronal MR tomograms and MR angiograms of the abdominal vessels were obtained and superimposed by a specially created computer program. By using a Subtraskop the MRT/MRA superposition was geometrically projected onto the simulation film in correct scale. The target volume could individually be defined and was compared to standard treatment planning according to the definition by Abbatucci. In all patients an exact irradiation of the spleen, the splenic pedicle and prominent lymphatic masses was possible. Furthermore, this resulted in a 32% reduction of treated kidney volume in the average of patients. Noninvasiveness, acceptable costs and high accuracy support the application of this new method in clinical routine.

Abdomen↗

PubMedDate not supplied

Dynamic 3D-MR mammography: is there a benefit of sophisticated evaluation of enhancement curves for clinical routine?

The purpose of the study was to compare standard analysis with pharmacokinetic analysis of time-intensity curves in dynamic three-dimensional (3D) MR mammography (MRM) for their capability of differentiating benign from malignant disease. Dynamic MRM of the whole breast was performed at 1.0 T using an axial fast low-angle shot (FLASH) 3D sequence. For the standard evaluation, the enhancement of the first minute (E1) and the slope of enhancement from minute 2 to 10 (SE2-10) were calculated. For pharmacokinetic analysis, the amplitude of enhancement (A), distribution time (t21), and elimination time (tel) were computed. Sixty-two histologically verified lesions were evaluated. The standard evaluation methods yielded a highly significant difference between benign and malignant disease for E1 (P = .0008) and SE2-10 (P = .0001). The pharmacokinetic parameters gained similarly significant P values (A, P = .0014; t21, P = .0024; tel, P = .0001). Both standard and pharmacokinetic analysis concordantly discriminated between benign and malignant lesions in discriminant analysis. Compared with standard analysis, a pharmacokinetic analysis of time-intensity curves is not beneficial for routine clinical diagnosis.

Adolescent↗

PubMedDate not supplied

Clinical applications of MR angiography in intrathoracic masses.

This is a prospective evaluation of the use of MR angiography (MRA) at 1.5 T in the assessment of intrathoracic masses. Two-dimensional (2D) MRA was obtained sequentially by means of a fast low angle shot (FLASH) technique (repetition time 30 ms, echo time 10 ms, flip angle 30 degrees) one slice per breath-holding. An automated control procedure and instantaneous image reconstruction permitted constant monitoring of the image quality and tailoring of the timing of the scans to each patient's breathing capacity; MRA was successfully completed in all patients. Two-dimensional FLASH angiography was postprocessed into three-dimensional (3D) MR angiography (projections) by a maximum-intensity-projection algorithm; a 3D spatial impression of the MRA was achieved by obtaining 3D MRAs from different viewing angles and by viewing these in a cine-loop. Superimposition of vessels was avoided by creating angiograms of interest of a specific anatomic region. Fifteen patients with malignant or benign intrathoracic tumor were evaluated; their MR findings were correlated with chest radiography, conventional angiography, bolus enhanced CT, and/or perfusion scintigraphy. Magnetic resonance angiography revealed stenosis, distortion, and displacement of vessels by tumors as well as distal perfusion defects caused by proximal tumors. The MRA findings were readily accepted by our clinical colleagues and incorporated into their surgical planning. We believe MRA to be a promising complement to MR imaging in the assessment of intrathoracic masses.

Adult↗

PubMedDate not supplied

MRI and MRA in treatment planning of subdiaphragmatic radiation therapy.

Radiotherapy treatment planning needs optimum definition of target volume in its relative position to normal tissue. The aim of our study was to achieve individual field definition in subdiaphragmatic radiotherapy by visualization of the target volume using fast, breath-held MRI and MR angiography. A modified rapid acquisition SE technique (SE 150/10) was used to obtain a coronal image within a 14 s breath-holding period, displaying kidneys, spleen, and lumbar spine on one slice. Coronal MR angiography acquisition in breath-hold technique was performed using a sequential FLASH-2D sequence (FLASH-2D 30/10/30 degrees). For reconstruction of the MR angiogram in coronal view, we used a maximum intensity projection algorithm. A computer program superimposed the MR angiogram onto the MR image. Correct magnification of the superposition image allowed direct projection onto the simulation film. Problems of distortion and different projection techniques were taken into account and quantified by phantom measurements. The localization error measured in a reference plane was less than 5 mm within a radius of 140 mm. Fourteen cases of Hodgkin disease and non-Hodgkin lymphomas were treated employing the novel technique. By superposition of the MR image and the MR angiogram, demarcation of vascular architecture from parenchymatous organs was achieved. Projection of the MR superposition onto the simulation film yielded accurate and convenient field definition using noninvasive imaging techniques.

Abdomen↗