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T Krahe

Publications and source records attributed to T Krahe.

At least 19 recordsLinked to original sources
PubMed2003

Clinical and diagnostic value of preoperative MR mammography and FDG-PET in suspicious breast lesions.

Dynamic enhanced magnetic resonance (MR) mammography and fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) of the breast were directly compared preoperatively in suspicious breast lesions. Forty-two breast lesions in 40 patients were examined with a three-dimensional dynamic MR imaging series and FDG-PET. The MR and PET examinations were evaluated separately and the results were compared with the histological findings. The sensitivity and specificity of each method were calculated. The diagnostic value of both modalities as single diagnostic tool and in combination was investigated. Nineteen malignant and 23 benign breast lesions were proven histologically. Magnetic resonance mammography and FDG-PET showed a sensitivity of 89 and 63%, respectively. The specificity was 74 and 91%, respectively. The combination of both imaging methods decreased the not-required biopsies from 55 to 17%. Only one false-negative finding-a patient pre-treated with chemotherapy-was observed in both methods. The combination of MR mammography and FDG-PET can help to decrease biopsies of benign breast lesions. Because of their high cost, these modalities should only be used in problematic cases to either rule out or to demonstrate malignancy. The best diagnostic strategy is achieved using MR mammography first. If the diagnosis is still questionable, FDG-PET can be performed.

Breast↗
PubMed1999

Ferric ammonium citrate as a positive bowel contrast agent for MR imaging of the upper abdomen. Safety and diagnostic efficacy.

PURPOSE: To evaluate the safety and diagnostic efficacy of two different doses of ferric ammonium citrate as a paramagnetic oral contrast agent for MR imaging of the upper abdomen. MATERIAL AND METHODS: Ninety-nine adult patients referred for MR imaging for a known or suspected upper abdominal pathology were included in this randomized multicenter double-blind clinical trial. Imaging was performed with spin-echo (T1- and T2-weighted) and gradient-echo (T1-weighted) techniques before and after administration of either 1200 mg or 2400 mg of ferric ammonium citrate dissolved in 600 ml of water. Safety analysis included monitoring of vital signs, assessment of adverse events, and laboratory testing. Efficacy with regard to organ distension, contrast distribution, bowel enhancement and delineation of adjacent structures was graded qualitatively. RESULTS: No serious adverse events were reported for either of the two concentrations. A total of 31 minor side effects were noted, of which significantly more occurred in the higher dose group (p<0.01). The diagnostic confidence in defining or excluding disease was graded as better after contrast administration for 48% of all images. Marked or moderate enhancement of the upper gastrointestinal tract was achieved at both doses in 69.5% of cases with no evident difference between the two doses. The higher dose tended to show better results in terms of the contrast assessment parameters. CONCLUSION: Ferric ammonium citrate is a safe and effective oral contrast agent for MR imaging of the upper abdomen at two different dose levels. The higher dose showed a tendency toward better imaging results while the lower dose caused significantly fewer side effects. Therefore the 1200 mg dose can be recommended in view of the risk-to-benefit ratio.

Abdomen↗
PubMed1998

Influence of the hepatobiliary contrast agent mangafodipir trisodium (MN-DPDP) on the imaging properties of abdominal organs.

To assess the influence of Mangafodipir Trisodium on the imaging properties of abdominal organs when using T1-weighted gradient-echo (GE) and T2-weighted turbo spin-echo (TSE) sequences, thirty patients with focal lesions in the liver were examined at a field strength of 1.5 T before and after intravenous administration of Mangafodipir Trisodium (dose: 5 micromol/kg of body weight). Administration of Mangafodipir Trisodium led to a significant increase in the signal intensity of the liver tissue (p < 0.001), the spleen (p < 0.01), the pancreas (p < 0.001), and the kidneys (p < 0.001) in the T1-weighted GE sequence, while there was no relevant enhancement in fatty tissue and the musculature. In the T2-weighted turbo spin-echo sequence, there was no relevant change in the signal following administration of a contrast agent. The contrast-to-noise ratio (C/N) between the lesions and the liver tissue increased significantly in the post-contrast T1-weighted GE sequence (p < 0.001), while there was no change in the contrast-to-noise ratio in the post-contrast T2-weighted turbo spin-echo sequence. The contrast-to-noise ratio of the plain T2-weighted TSE sequence was significantly higher than that in the post-contrast T1-weighted GE sequence (p < 0.001). Although Mangafodipir Trisodium was primarily developed as a hepatobiliary contrast agent for demonstration and differentiation of liver lesions, it also affects the signal levels in the pancreas, spleen, and kidneys in the T1-weighted image. Awareness of this effect on the extrahepatic tissue makes it easier to interpret pathological findings in magnetic resonance imaging (MRI) of the abdomen.

Abdomen↗
PubMed1998

[Correlation of MRI and histopathological findings in inflammatory skin diseases].

PURPOSE: Can spatial and contrast resolution be achieved with currently available MR devices for the successful assessment of inflammatory diseases of the skin? METHOD: High resolution MRI was performed in 20 patients with non-malignant diseases of the dermis and subcutis. The skin biopsies subsequent to the MR examinations were indicated for clinical reasons. The MR examinations were done in the location of later performed skin biopsies using a 1.0 Tesla system (Gyroscan T10 NT, Philips, Best, the Netherlands) and a surface coil of 7.5 cm inner diameter. Conventional spin-echo (SE-Sequenz)- and gradient-echo (GRE)-sequences were optimised to obtain maximum spatial resolution with a sufficient signal-to-noise ratio within a tolerable examination time. MR visualisation of histopathology was assessed by four readers using a questionnaire. RESULTS: In 15 of 20 cases, high resolution MRI allowed a correct classification of the visualised dermal and subcutaneous patterns, in accordance with the histological work-up of the corresponding specimen. Due to the still only suboptimal spatial and contrast resolution the structure of the epidermis could not be assessed adequately. Determination of contrast enhancement or non-enhancement after administration of intravenous contrast agent provided information on the degree of tissue perfusion in 19 patients, which complemented the morphological assessment. CONCLUSION: High resolution MRI allows to identify non-invasively histological main patterns of inflammatory skin diseases. However, final diagnosis often depends on higher microscopic resolution and special staining.

Adolescent↗
PubMed1998

[Complications of CT guided lumbar sympathectomy: our own experiences and literature review].

AIM: To review the complications of CT guided lumbar sympathicolysis (CTLS) on the basis of our own experience and the available literature. METHODS: 241 CTLS were performed by a standard technique according to Haaga's method. Clinical follow-up revealed 4 serious complications; these were analysed and compared with published cases. RESULTS: Amongst our patients there were three fibrotic ureter stenoses and one retroperitoneal abscess. Analysis of the serious complications described in the literature indicates that introduction of CT guided lumbar sympathicolysis has reduced the severity and frequency of complications as compared with surgical and "blind" procedures. With CTLS, no deaths due to the procedure have been reported in the literature. The results indicate that damage to the ureters can be caused by substances used for the neurolysis. CONCLUSION: Provided certain safeguards are obeyed, CTLS is a very save treatment. However damage to the ureter may follow even when the procedure was technically satisfactory. Therefore, sonographic control of the kidneys after three months is recommended.

Abscess↗
PubMed1998

[Endorectal MRI and ultrasonography in rectal tumors: correlation with histological staging].

PURPOSE: To compare the accuracy of high resolution endorectal magnetic resonance imaging (EMRI) and endorectal ultrasound (EUS) in the preoperative diagnostic of rectal tumours. PATIENTS AND METHODS: Twenty-one patients with known rectal tumours underwent MR imaging with an endorectal surface coil and EUS. Transversal EMR images were obtained using fast T2-weighted sequences and pre- and postcontrast T1-weighted images. EUS was performed using a 7.0 MHz transducer. Results of both methods were compared with specimens from the resected tumours. RESULTS: Rectal wall layers were reliably demonstrated with both methods in all patients. EMRI and EUS determined the depth of rectal wall invasion. EMRI and EUS agreed with pathologic findings in 16/21 cases, respectively. In one case each, both methods understaged one tumour. EMRI overstaged an adenoma as a T2-tumour. In three and four patients, respectively, no staging was possible due to technical problems. CONCLUSION: EMRI and EUS show comparable results in the preoperative T-staging of rectal tumours. Both techniques are not suitable for differentiating benign from malignant lymph nodes accurately. While EMRI is expensive and technically demanding, it allows an objective documentation of pathological findings which is less dependent on the examiner. Two important clinical conclusions can be drawn from the good results of T-staging: Adenomas and T1-tumours can be treated by local excision. In patients with advanced tumours (T3/T4) a neoadjuvant therapy can be initiated.

Adenoma↗
PubMed1998

High-resolution MR imaging of the cutis and subcutis. Histological correlation.

OBJECTIVE: To determine whether the spatial resolution that can be achieved with currently available MR devices is adequate for the evaluation of skin disease. MATERIAL AND METHODS: We correlated high-resolution MR images of the skin with dermatohistopathology in 26 patients. The examinations were carried out on a 1.0 T imager using a commercially available surface coil (ID 7.5 cm) and optimized SE and GE sequences. Image quality was assessed by four readers on a questionnaire. RESULTS: The visualization of the dermis, subcutaneous tissue, and muscle fascia allowed a pattern analysis that gave findings identical to those at dermatohistopathology. It was possible to distinguish septal from lobular panniculitis, and lipatrophia from sclerodermia. Images with contrast media infusion were useful in the differential diagnosis. CONCLUSION: High-resolution MR imaging may narrow down the differential diagnosis of various skin diseases and may help to reduce the number of skin biopsies on certain indications.

Adolescent↗
PubMed1998

Detection of focal hepatic lesions: effects of superparamagnetic iron oxide (AMI-25) on magnetic resonance imaging of the liver using T2-weighted fast spin-echo sequences and gradient-and-spin-echo sequences at 1.0 tesla.

RATIONALE AND OBJECTIVES: The authors evaluate the value of two fast spin-echo sequences (FSE) with different T2-weighting (repetition time [TR]/echo time [TE] = 2000/90 mseconds and TR/TE = 2000/40 mseconds) and combined gradient-and-spin-echo sequences (TR/TE = 2000/90 mseconds) for contrast-enhanced liver imaging with superparamagnetic iron oxide (AMI-25). METHODS: Forty-seven patients with focal liver lesions underwent magnetic resonance imaging at 1.0 tesla. AMI-25 was administered intravenously at a dose of 15 micromol iron/kg. RESULTS: Administration of AMI-25 resulted in a significant increase of lesion/liver contrast-to-noise ratio (C/N) for all T2-weighted sequences (P < 0.001). On the precontrast images, the FSE sequence with a TE of 90 mseconds had the highest C/N (16.0 +/- 4.5) whereas the best postcontrast C/N (27.9 +/- 7.6) was obtained with the mild T2-weighted FSE sequence with a TE of 40 mseconds. CONCLUSIONS: Fast spin-echo sequences are valuable sequences for imaging of the liver at 1.0 tesla. For AMI-25-enhanced magnetic resonance imaging, a mild T2-weighted FSE sequence is recommended.

Adult↗
PubMed1997

[Localization of puncture needles in MRI: experimental studies on precision using spin-echo sequences at 1.0 T].

PURPOSE: To evaluate accuracy of needle localisation using and signal enhancement on a 1.OT MR imager for various needles for MR-guided biopsy. METHODS: The differences between actual and virtual needle position of needles with different orientations were evaluated in a phantom for spin-echo including turbo-spin-echo sequences. RESULTS: Artifacts depended on the orientation of the needle relative to the field B0, frequency-encoding gradients (Gf) and slice orientation. This resulted in different artifact shapes and sizes for left or right and cranial or caudal biopsy access routes. Applying turbo spin echo sequences feasible for biopsy, the signal void of a 18 G needle (Cook) parallel to Gf reached between 0.3 and. 4.6 mm further into the medium than the real needle tip, depending on needle orientation relative to B0. The diameter of the signal void around the needle varied, the needle shaft was right in the centre of the signal void. With Gf orthogonal to the needle the offset of signal void to needle tip ranged from 2.7 to 3.3 mm, while the actual position of the needle shaft was up to 3.3 mm lateral of the signal void center. While nominal echo times did not influence the size of the artifact in turbo-spin-echo sequences, the artifacts increased with smaller matrix and larger water-fat shift. Material and mass of the needle determined the size of the artifacts as well. CONCLUSION: Localisation accuracy of the needle can be optimised by choosing optimal gradient directions depending on whether needle tip or shaft position should be displayed.

Artifacts↗
PubMed1997

[Computer-assisted control of CT-guided caudo-cranial puncture access route using the triangulation method].

PURPOSE: To control the position of a puncture needle on an access route, which is not parallel to the CT-scan, using control scans not showing start and target points. METHODS: A software tool has been developed. After CT for biopsy planning x/y coordinates and table position of start and target points have to be determined on CT-scans. The software calculates x/y coordinates of the access route for every table position, which must be marked interactively on control scans. The accuracy of the programme was proven experimentally and the method was used in five patients. RESULTS: There was no difference between the calculated and measured access route in the experiment. Four of five patients were punctured successfully using our method. CONCLUSION: Our method is a promising procedure to control a CT-guided caudo-cranial biopsy access route.

Biopsy, Needle↗
PubMed1996

[Computerized tomography volumetry of the cerebrospinal fluid by semiautomatic contour recognition and gray value histogram analysis].

PURPOSE: A program (VAC, Siemens) using self-made, anthropomorphous phantoms to measure semiautomatically the volume of the cerebral liquor in CT scans of the whole skull was tested. MATERIAL AND METHODS: Cerebral tissue was simulated by ellipsoid bodies made from Agar and NaI which were placed in a human skull. Volumes of the ventricular and subarachnoidal liquor could be defined arbitrarily. RESULTS: A correlation coefficient of r > = 0.9 using a slice thickness of 1-5 mm was found (thickness 8 mm: r = 0.75). The volume of the cerebral liquor was underestimated by 25-68%. Separate measurements of the ventricular and subarachnoidal liquor spaces showed a high accuracy of the measurements done in the ventricles (r = 0.997, y = 0.996 x -1). The volume of the subarachnoidal liquor was not detected completely due to partial volume effects which were seen especially in the basal and apical scans. CONCLUSION: The program VAC is useful for the semiautomatic measurement of the volume of the ventricles. The assessment of the subarachnoidal liquor is limited to semiquantitative results which may, however, be useful for follow-up studies.

Brain↗
PubMed1996

[Comparison of fast turbo-spin-echo and gradient- and spin-echo sequences as well as echo planar imaging with conventional spin-echo sequences in MRI of focal liver lesions at 1.0 tesla].

PURPOSE: To evaluate the value of rapid T2-weighted turbo-spin sequences (TSE), turbo-spin-echo sequences with shortened echo spacing (UTSE), gradient-and-spin-echo sequences (GraSE) and T1-weighted echo-planar imaging (EPI) in comparison with conventional spin-echo sequences (SE) in the diagnosis of focal liver lesions. METHODS: 20 patients with malignant focal liver lesions underwent magnetic resonance imaging at 1.0 tesla. RESULTS: The use of fast T2-sequences (TSE, UTSE, GraSE) reduced the examination time to about 35-50%. Artifacts were reduced compared with the conventional T2-SE sequence. Quantitative analysis demonstrated that UTSE imaging had the highest tumor/liver contrast-to-noise ratio (CNR) followed by TSE, T2-SE and GraSE sequences. CNR with EPI was lower than with the T1-SE sequence (p < 0.05). CONCLUSION: Turbo-spin-echo sequences with shortened echo spacing yield a shorter imaging time and improved image quality without loss of signal intensity in tumor/liver-CNR, compared with conventional T2-pulse sequences in liver imaging at 1.OT.

Adult↗
PubMed1996

Delineation of segmental liver anatomy. Comparison of ultrasonography, spiral CT and MR imaging for preoperative localization of focal liver lesions to specific hepatic segments.

PURPOSE: The purpose of this study was to determine the ability of noninvasive imaging methods to localize focal liver lesions to specific hepatic segments. MATERIAL AND METHODS: In a prospective study we evaluated 24 patients with hepatic masses with ultrasonography (US), spiral CT and MR imaging. RESULTS: The primary segmental location of the lesions was correct with US in 15 of 24 patients (63%), with CT in 21 of 24 patients (88%) and with MR imaging in 17 of 22 patients (77%). The full extent of the lesions was correctly described with US in 9 of 24 patients (38%), with CT in 16 of 24 patients (67%) and with MR in 12 of 22 patients (55%). CONCLUSION: Among the noninvasive imaging methods, CT provides the best information for determining the segmental location and planning the surgical approach to hepatic resections.

Contrast Media↗
PubMed1995

[Quantitative computed tomographic determination of spleen size to assess the course of malignant lymphomas].

The purpose of this study was to correlate CT-assessed spleen indices (length x width x depth) and their changes under therapy or in the follow-up, with the clinical course and morphological changes. In 66 patients with 200 CT's of the abdomen the spleen index was calculated and 134 spleen index differences (delta SI) were correlated with the clinical outcome. The normal group showed a mean of delta SI of -8 = 112, equivalent boundaries of -120 and 104. delta SI of progressive lymphomas (n = 32) was 313 (p < 0.01). In 10/14 patients of this group, morphological signs of infiltration were found. In regressive lymphomas (n = 63) we found delta SI = -211 (p < 0.001). 23/29 with delta SI < -120 showed signs of spleen involvement in the preliminary examination. Since there are only slight intraindividual changes of CT-assessed spleen indices and a good correlation of spleen index differences with the clinical outcome. the spleen index is a useful instrument in the follow-up of malignant lymphomas.

Disease Progression↗
PubMed1995

[Quantification of lymph node perfusion using color duplex ultrasonography].

PURPOSE: 20 parameters were defined to differentiate benign from malignant lymphadenopathy using computer assisted analysis of the lymph node perfusion demonstrated by colour Doppler flow imaging. MATERIAL AND METHODS: In 112 lymph nodes a computer assisted analysis of 10 consecutive colour Doppler flow sonograms was performed after digital data transfer to a work station. Planimetric results, the colour coded Doppler shift frequency, changes of the perfusion during the heart cycle and the perfusion in the adjacent tissue were analysed using 20 parameters. RESULTS: Discriminant analysis resulted in 7 parameters which reclassified correctly 82% of the lymph nodes (sensitivity 84%, specificity 80%). 72% of the lymph nodes could be classified in the three groups reactive lymphadenopathy, lymph node metastasis and malignant lymphoma. CONCLUSIONS: Clinically known subjective signs of malignancy (increased size, low echogenicity, alterations of the perfusion) can be analysed quantitatively to differentiate benign from malignant lymphadenopathy.

Diagnosis, Differential↗
PubMed1995

[Value of computed tomography in the diagnosis of fistulas].

PURPOSE: The purpose of the study was to determine the value of computed tomography (CT) in demonstrating fistulae in comparison with conventional radiographic methods. METHODS: In a prospective study 25 patients were evaluated by conventional radiographic methods and CT. RESULTS: The identification of the fistulous tract was possible with CT in 27 of 29 cases, whereas 2 fistulae could only be detected by indirect signs. Furthermore, CT showed a larger extent of the fistulous tract in 5 patients and revealed complications such as inflammatory mass, abscess or osteomyelitis in 11 cases. CONCLUSION: CT seems to be superior in demonstrating the extent of a fistulous tract and provides valuable information on the surrounding structures.

Adult↗
PubMed1995

Digital luminescence radiography and conventional radiography in abdominal contrast examinations.

In 326 patients abdominal contrast radiographs were compared to digital luminescence radiographs (DLR) and conventional screen-film system ones. The digital exposure dose was 50% of the conventional. In DLR, 2 different types of postprocessed images were obtained from each data set. A display with low spatial frequency enhancement filtered to look like a conventional radiograph was compared to a display with high spatial frequency enhancement. Conventional and DLR images were evaluated randomly and separately by 4 radiologists by means of a questionnaire. DLR proved to be diagnostically equivalent to the conventional technique with the exception of a slightly diminished visibility of the mucosal pattern. High spatial frequency enhancement did not provide additional diagnostic information and should be dispensed with in abdominal examinations.

Adult↗