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ABSTRACT: Intracranial lesions are often characterized by different elasticities. The aim of the present study was to test the application of vibrography during brain tumor surgery.
The real-time vibrography system consisted of a conventional ultrasound system (Siemens Sonoline Omnia) with a custom-designed RF interface and a 6.5-MHz endocavity curved array (Siemens 6.5EC10). The RF data were digitized using a 50-MHz, 12-bit PCI analog/digital (A/D) converter for real-time or offline processing. Static compression was replaced by low-frequency axial vibration of the probe. A special applicator equipped with a stepping motor moved the ultrasonic probe and produced a low frequency mechanical vibration of 5-10 Hz with a vibration amplitude of 0.3 mm and slight preliminary compression (total<1 mm). The maximum application time was 60 sec. A pneumatic holding device (Unitrac, Aesculap, Tuttlingen, Germany) was used.
Brain tissue is normally color coded between red and orange. In this study 41 out of 45 tumors could be detected via vibrography. Two tumors could not be detected with this imaging technique: a glioblastoma at a depth of 2 cm and a metastasis at a depth of 3 cm. Two additional tumors were not recognized because of technical problems. In 4 cases tumors with strain values identical to those in brain tissue (coded red or orange) but easily identified by a peripheral zone of high strain (yellow) were found. Tumors with strain values higher than those measured in brain tissue coded yellow and were softer than brain during surgical intervention. Higher strain was found in 23 tumors. Tumors with strain values lower than those in cerebral tissue were found to be harder during surgery and coded brown or black. Lower strain was found in 10 cases. Four tumors were inhomogeneous and could not be assigned to one of the above groups. Mortality was 0%, morbidity 2.3%. One patient displayed transient paresis of the lower extremity due to microsurgical difficulties during the approach. In one patient minimal bleeding of the cortical surface occurred in a frontobasal tumor; however, no postoperative deficits were noted.
Vibrography is a new low-risk technique for intraoperative imaging. In low-grade astrocytomas and oligodendrogliomas, this additional technique can be used to control resection. In other cortical and subcortical tumors (e. g. metastases), it can provide an impression of the intratumoral elasticities.
Ultraschall in der Medizin 10/2007; 28(5):493-7. · 2.40 Impact Factor
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H J Sommerfeld,
J M Garcia-Schürmann,
J Schewe,
K Kühne,
F Cubick,
R R Berges,
A Lorenz, A Pesavento,
U Scheipers,
H Ermert,
J Pannek,
S Philippou,
T Senge,
S Scheipers
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ABSTRACT: During the last decade screening has improved prostate cancer detection. The main reason for this development is a better understanding of the margins of prostate-specific antigen (PSA) serum levels and the classification of PSA subtypes. In contrast, the introduction of transrectal ultrasound has not led to a measurable change in the prostate cancer detection rate. Our aim was to develop a novel ultrasound system for the acquisition of elastographic images of the prostate and evaluate the system regarding its clinical applicability. We used a technically modified conventional ultrasound system and analyzed the high-frequency ultrasonic data with a computer program. The first patient-based results suggest that elastography allows an accurate measurement of tumor size and localization in contrast to conventional transrectal ultrasound. Elastography visualizes different tissue elasticities to distinguish benign and cancerous tissue. Thus, we were able to even correctly classify prostate cancer lesions which are iso- or hyperechoic in B-mode sonography.
Der Urologe 08/2003; 42(7):941-5. · 0.50 Impact Factor
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H.-J. Sommerfeld,
J. M. Garcia-Schürmann,
J. Schewe,
K. Kühne,
F. Cubick,
R. R. Berges,
A. Lorenz, A. Pesavento,
S. Scheipers,
H. Ermert,
J. Pannek,
S. Philippou,
T. Senge
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ABSTRACT: Zusammenfassung Frherkennungsmanahmen haben im letzten Jahrzehnt zu einer verbesserten Prostatakarzinomdetektion gefhrt. Dies ist einerseits auf ein gestiegenes Krankheitsbewusstsein und andererseits auf eine verbesserte Diagnostik zurckzufhren. Das prostataspezifische Antigen (PSA) ist gegenwrtig der wichtigste diagnostische Parameter. Der transrektale Ultraschall konnte im Gegensatz dazu die in ihn gesetzten Erwartungen nicht erfllen. Zielsetzung der vorliegenden Arbeit war es, ein System zu entwickeln und klinisch zu erproben, das es erlaubt, die Ultraschallelastographie hinsichtlich ihrer Einsatzmglichkeiten in der Prostatakarzinomdiagnostik zu beurteilen. Eine rechnergesttze Aufarbeitung von hochfrequenten Ultraschallsignalen, die an einem handelsblichen Ultraschallgert mit technischen Modifikationen abgegriffen wurden, erlaubte uns eine erste klinische Evaluation. Die durchgefhrten Untersuchungen an Patienten konnten zeigen, dass die Elastographie die Lokalisation und Ausdehnung eines Prostatakarzinoms genauer erfasst als es mit dem konventionellen Ultraschall mglich ist. Das gewhlte Abbildungsverfahren nutzt eine unterschiedliche Gewebeelastizitt zwischen Tumor und normalem Gewebe und erkennt auch Tumoren, die im B-Bild iso- oder hyperechoisch zur Darstellung kommen.
Der Urologe 06/2003; 42(7):941-945. · 0.50 Impact Factor
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ABSTRACT: The incidence of the prostate carcinoma is one of the highest cancer risks in men in the western world. Its position in cancer mortality statistics is also among the highest. The different types of diagnostics that are used today lack reliability and are therefore not sufficient. Diagnosis of the prostate carcinoma using multifeature tissue characterization in combination with ultrasound allows the detection of tumors at an early stage and thus can aid the conducting physician in finding a diagnosis. Spatially resolved parameters and contextual information are used for the classification. Next to hypo- and hyperechoic tumors, also isoechoic tumors can be visualized.
Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE; 11/2002
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12/2001: pages 253-259;
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ABSTRACT: The incidence of the prostate carcinoma is one of the highest
cancer risks in men in the western world. Its position in cancer
mortality statistics is also among the highest. The prostate carcinoma
is only curable at an early stage. Therefore, early detection is
extremely important. At an early stage the prostate carcinoma is limited
to the prostate capsule and can hence be cured performing radical
prostatectomy. The different types of diagnostics that are used today
(digital rectal examination, transrectal ultrasound and PSA value
analysis) lack reliability and are therefore not sufficient. Even a
combination of these three methods is not sufficiently reliable.
Diagnosis of the prostate carcinoma using multi-feature tissue
characterization in combination with ultrasound allows the detection of
tumors at an early stage. Also biopsy guidance and planning can be
improved. This results in reduced costs for cancer treatment
Ultrasonics Symposium, 2001 IEEE; 02/2001
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ABSTRACT: Prostate tumors can have a higher mechanical hardness than the
surrounding tissue. During the digital rectal exam this can be used not
only to detect the hypertrophy but also localized hardenings. The
examination by digital palpation is inaccurate and even in combination
with PSA-value and a transrectal ultrasonic examination the result is
often not reliable. Ultrasound strain imaging is able to measure and
visualize the elastic properties of a tissue region and hence is an
adequate supplement for commonly used diagnostic procedures. We have
developed a real time system for elastographic mechanical tissue
assessment of the prostate which can be used for the transrectal
ultrasonic examination for navigation and diagnosis. During the
examination a sequence of ultrasonic images is acquired while the organ
is slightly compressed by the ultrasound probe. Using a numerical
analysis of image pairs of the acquired sequence the tissue strain is
calculated which represents the spatial elasticity distribution of a
specific cross-section of the organ and which are able to distinguish
hard areas in the tissue. We present results from several patients which
show that real time strain imaging is able to detect tumor-like areas
which are inconspicuous in the b-mode image. The results correspond to
the histological specimens. After the evaluation of 170 patients using a
prospective study we found the specificity for cancer detection to be
approximately 84% and a sensitivity of approximately 76%. Furthermore
the tumor location and extend was correctly predicted in most of the
investigated patients using our real time strain imaging
Ultrasonics Symposium, 2001 IEEE; 02/2001
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ABSTRACT: Assesses the second order statistical properties of strain images
with respect to the temporal direction. Successively acquired strain
images in a real-time or similar off-line strain imaging system are
correlated. This can be described by a covariance function, which is
investigated in this paper by simulations. We determine how the
statistical properties affect the choice of the frame-rate in a
real-time strain imaging system and furthermore the effect of temporal
filtering of strain images is discussed. The first in vivo real-time
strain images of the prostate have been presented
Ultrasonics Symposium, 2000 IEEE; 11/2000
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ABSTRACT: We present the development of a combined system which is able to
exploit the benefits of two methods used for tissue characterization,
strain imaging and tissue classification using a trainable
classification system. Our system is able to acquire in vivo
multi-compression rf-data for the calculation of the tissue strain, i.e.
the elastic properties of tissue, induced by tissue compression. At the
same time a neuro-fuzzy classification system is used to map the tissue
malignancy. In vivo classification results and in vivo strain images are
presented. The images of the two new modalities are compared to
demonstrate the advantages and restrictions of both methods
Ultrasonics Symposium, 2000 IEEE; 11/2000
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ABSTRACT: Ultrasound transmission imaging is an alternative promising
modality because unlike x-ray transmission this concept is not ionizing
and has a good contrast in tissue imaging. Our concept enables also real
time imaging. Earlier designs of transmission cameras with a 2D-array
and an acoustic lens suffered from high costs, large size and a limited
imaging quality, which finally caused those cameras not to become a
commercial product. We developed a novel compact low-cost ultrasound
transmission camera. With a center frequency of 3 MHz a resolution of 1
mm in both lateral dimensions was achieved over a field of view of
80×80 mm<sup>2</sup>. Real time images of moving joints and
tendons are displayed with a frame-rate of 25 1/s. The major fields of
application are orthopedics, pediatrics and diagnosis of rheumatic
arthritis
Ultrasonics Symposium, 2000 IEEE; 11/2000
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ABSTRACT: Two real-time strain imaging concepts and systems are presented. Both systems are based on a conventional ultrasound scanner that is connected to a PC with an A/D converter card for real-time data acquisition of rf data. Differential strain between successively acquired rf frames are estimated using phase root seeking. The first concept uses a special real-time implementation of manual elastography. In the second concept, denoted 'vibrography', the static compression is replaced by low-frequency axial vibration of the probe, still operating in quasistatic acquisition mode. The properties of both concepts are discussed with regard to noise and motion artefacts, and it is shown, using simulations and phantom experiments, that both imaging concepts yield the same kind of strain images. Vibrography has the advantage that no manual compression has to be applied, total compression can be very low and some motion artefacts are better suppressed.
Physics in Medicine and Biology 07/2000; 45(6):1423-35. · 2.83 Impact Factor
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ABSTRACT: In ultrasonic elastography, the exact estimation of temporal displacements between two signals is the key to estimating strain. An algorithm was previously proposed that estimates these displacements using phase differences of the corresponding base-band signals. A major advantage of these algorithms compared with correlation techniques is the computational efficiency. In this paper, an extension of the algorithm is presented that iteratively takes into account the time shifts of the signals to overcome the problems of aliasing and accuracy in the estimation of the phase shift. Thus, it can be proven that the algorithm is equivalent to the search of the maximum of the correlation function. Furthermore, a robust logarithmic compression is proposed that only compresses the envelope of the signal. This compression does not introduce systematic errors and significantly reduces decorrelation noise. The resulting algorithm is a computationally simple and very fast alternative to conventional correlation techniques, and the accuracy of strain images is improved.
IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control 10/1999; · 1.69 Impact Factor
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ABSTRACT: A system is presented that continuously displays images of the strain distribution with up to 5 frame/s obtained by manually or semi-manually compressing or releasing the tissue during an ultrasound examination. The RF-echo data are sampled by a conventional desktop PC and images of the axial strain are calculated using the fast phase root seeking technique. Up to five elastograms per second of a tissue region of approximately 3.7 cm ×3.5 cm are displayed.
Electronics Letters 06/1999; · 0.96 Impact Factor
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ABSTRACT: Recently, we developed an algorithm for fast and accurate time shift measurement using an iterative algorithm which calculates the time shift of two signals by iteratively seeking the zero of the phase of the complex correlation function. Typically only 2 or 3 iterations are needed. With this contribution we extended the algorithm to perform an estimation and correction of lateral displacements and adaptive temporal stretching. Both significantly reduce the noise of the strain estimation. 1. INTRODUCTION A major problem of elastography is the low SNR of strain images. Inspite of noise on the rf-data, the echo decorrelation is the major noise source. It is caused by the strain itself (axial compression), lateral motion and out of plane motion. While the latter is a problem of signal acquisition, all other decorrelation errors can be reduced by signal processing: in the past the use of 2D-correlation techniques [5] and adaptive temporal stretching [1] have successfully been applied. Ho...
04/1999;
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ABSTRACT: With the Phase-Root-Seeking algorithm a new and very fast
algorithm for time delay estimation was recently introduced, permitting
the estimation of strain images in real-time. In this paper the accuracy
of the real-time strain imaging concept is investigated by the most
rigorous approach, i.e. a comparison to the theoretical accuracy limit:
the Cramer-Rao-Lower-Bound. Simulations show, that this limit can be
approximately reached by carefully selecting window length and window
shift for time delay estimations and using a generalized least square
estimator for the estimation of strain from time delays
Ultrasonics Symposium, 1999. Proceedings. 1999 IEEE; 02/1999
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ABSTRACT: Presents a new system for fast and efficient acquisition of
ultrasonic three-dimensional data sets for strain imaging. The authors
apply their technique to a typical strain imaging phantom which consists
of a soft sponge with a hard inclusion. With this set-up they
demonstrate the applicability of the proposed system. Using this system
they demonstrate the presence of a three-dimensional strain artifact
Ultrasonics Symposium, 1999. Proceedings. 1999 IEEE; 02/1999
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ABSTRACT: An ultrasonic imaging system is presented for diagnostics of post
discotomic scarring. The system images parameters derived from a Maximum
Likelihood Estimation of generalized K-distribution parameters. This
approach is capable to discriminate between Rayleigh-, structural- and
Pre-Rayleigh scattering. The system uses multidirectional echo data of
the same cross-sectional plane, obtained by a 5 MHz sector scanner that
is linearly moved over the human back. This leads to a resolution of the
parameter images of approximately 1 mm×1 mm
Ultrasonics Symposium, 1998. Proceedings., 1998 IEEE; 02/1998
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ABSTRACT: We implemented an ultrasonic strain imaging system to support the
tissue characterization of the female breast. The breast is compressed
between two plates of polyethylene and of steel, respectively. 3D
elastographic raw data of the breast can be acquired. The displacement
is estimated by finding the phase root of the cross-correlation between
the pre- and post-compression complex base-band echoes. The estimation
is enhanced by 3D “optical flow”: we estimate transversal
(lateral and out of plane) displacement which is used to correct the
axial trajectories in the post-compression image. In spite of the low
signal-to-noise ratio of single compression elastograms, transversal
displacements, and motion artifacts, encouraging strain images are
obtained. We will demonstrate the performance of this technique by
phantom and in vivo results
Ultrasonics Symposium, 1998. Proceedings., 1998 IEEE; 02/1998
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Biomedizinische Technik 02/1998; 43 Suppl:148-9. · 0.86 Impact Factor
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ABSTRACT: A compression algorithm is presented, which utilizes the special
properties of ultrasonic radio frequency (RF) data. The compression is
done in two steps: First, linear predictive coding (LPC) is applied,
using an one-step-predictor. Further, the remaining error of the
prediction is stored using only the necessary word length to store the
signal. A lossy extension of the algorithm is presented, which stores
only the upper bits of the error signal. The algorithm has been tested
with both, data of a speckle phantom and in vivo data. The data could be
compressed to approximately 30-55% of the original data size using the
lossless algorithm. In comparison, a conventional compression tool
achieves 65-75 % of the original data size
Ultrasonics Symposium, 1997. Proceedings., 1997 IEEE; 11/1997
