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At least 235 records · Page 13Linked to original sources
PubMed2006

Evaluation of CH3-DTPA-Gd (NMS60) as a new MR contrast agent: early phase II study in brain tumors and dual dynamic contrast-enhanced imaging.

PURPOSE: A newly developed contrast material, CH3-DTPA-Gd (NMS60), a trimer containing 3 Gd(3+) atoms per molecule, has been shown to offer greater enhancement and longer vascular retention than gadopentetate dimeglumine (Gd-DTPA) in animals. We report on our early phase II study on NMS60 in brain tumor patients together with supplementary investigations. METHODS AND MATERIALS: The longitudinal relaxation rate (R(1)=1/T(1)) and the transverse relaxation rate (R(2)*=1/T(2)*) of NMS60 and Gd-DTPA were determined at 20 degrees C in water at 1.5 T. An NMS60 dose of 0.1 or 0.2 mmol (Gd)/kg was randomly assigned and administered to 10 patients (five women, five men; mean age: 49 years) with brain tumors. Safety and contrast-enhancing ability of NMS60 were evaluated. Dual dynamic contrast-enhanced T(1) and R(2)* studies (DUCE imaging) were also carried out in two patients. RESULTS: Regarding the relaxivity per Gd, R(1) and R(2)* of NMS60 were 9.5 and 11.0 (mmol/L x s)(-1), respectively, compared to 4.8 and 7.2 (mmol/L x s)(-1) for Gd-DTPA. Although a transient slight increase of alanine aminotransferase was observed in one case, no other adverse reactions were observed after administration of NMS60. Contrast enhancement by NMS60 was excellent at both concentrations, and when tumor detectability was assessed with a five-point scale, the diagnostic usefulness was 4 or higher in all cases. In DUCE imaging, NMS60 appeared to show high signal intensity, when compared with the data obtained separately for Gd-DTPA. CONCLUSION: NMS60 had a high contrasting effect and little toxicity, and is expected to be clinically useful.

Brain↗
PubMed1997

CT image enhancement with wavelet analysis for the detection of small airways disease.

Bronchiolar obstruction is commonly manifested in computed tomography (CT) images as areas of decreased attenuation relative to adjacent normal lung parenchyma. The certain identification of such areas is difficult in practice, particularly if they are poorly marginated. This paper presents a novel approach to the enhancement of feature differences between normal and diseased lung parenchyma so that reliable visual assessment can be made. The method relies on a hybrid structural filtering technique which removes pulmonary vessels appearing in the CT cross-sectional images without affecting intrinsic subtle intensity details of the lung parenchyma. In order to restore possible structural distortions introduced by the hybrid filter, a feature localization process based on wavelet reconstruction of feature extrema is used. After contrast enhancement the resultant images are used to delineate region borders of the diseased areas and quantification is made with regard to the extent of the disease.

Bronchiolitis Obliterans↗
PubMed1996

Focal malignant hepatic lesions: MR imaging enhanced with gadolinium benzyloxypropionictetra-acetate (BOPTA)--preliminary results of phase II clinical application.

PURPOSE: To investigate enhancement with gadolinium benzyloxypropionictetraacetate (BOPTA) at magnetic resonance (MR) imaging to detect focal malignant hepatic lesions. MATERIALS AND METHODS: A phase II trial was performed in 34 patients. Gd-BOPTA-enhanced spin-echo (SE) and gradient-recalled-echo (GRE) T1-weighted MR imaging were performed at 40 and 90 minutes after intravenous injection of 0.05 and 0.10 mmol/kg Gd-BOPTA. RESULTS: The percentage of enhancement in liver parenchyma was significantly (P<.05) increased on GRE T1-weighted compared with SE T1-weighted images at 40 and 90 minutes after injection of the higher dose and compared with SE and GRE T1-weighted images obtained with the lower dose. The contrast-to-noise ratio of metastases was significantly increased on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast images. Significantly more small primary metastases were detected on GRE T1-weighted images (0.10 mmol/kg) at 90 minutes compared with precontrast SE T1-weighted images. CONCLUSION: Gd-BOPTA is a safe hepatobiliary contrast agent that helps detection of small metastases.

Contrast Media↗
PubMed1987

[Demonstration of brain tumors using a computer-assisted x-ray image enhancement technic].

It is possible to distinguish cerebral tumours from brain tissue after the injection of contrast by using an x-ray-video chain. Weak contrast situated behind strongly absorbing bone can be demonstrated by a nontomographic method by reducing the noise level and by using a special subtraction technique designed for optimal iodine contrast. For this examination, four series of images are prepared and stored (one before the administration of contrast and three subsequently). Dynamic studies of the distribution of contrast in the intra- and extra-vascular spaces of brain and tumour are produced by subtracting the stored images. The demonstration of blood-flow dynamics improves the differentiation of the tumour and, in particular, makes it possible to distinguish the tumour from cerebral oedema. The current input into the x-ray tube is low and the skin dose on the entry side is less than 0.6R for each series. The usefulness of the method in complementing computer tomography for surgical and radiation treatment is illustrated from various types of tumour. Up to the present 35 patients have been examined by this method.

Brain Neoplasms↗
PubMed1985

Image enhancement in computerized tomography for sensitive diagnosis of liver cancer and semiquantitation of tumor selective drug targeting with oily contrast medium.

A new type of anticancer agent with an amphiphilic nature, poly(styrene-co-maleic acid)-conjugated neocarzinostatin (Smancs), was dissolved in lipid contrast medium Lipiodol (Smancs/Lpd, Gelbet Co., Paris, France). This medium was injected arterially and found to be an invaluable tool for highly sensitive computerized tomography (CT) image analysis of tumors. After the administration, CT images revealed high-density areas which corresponded to the location and size of liver cancer, the smallest being 4 mm in diameter. The deposition pattern of Smancs/Lpd in liver cancers by CT was classified into three types. In type A, Lipiodol was distributed relatively even in the tumor lesion, whereas in type B it was accumulated predominantly around the tumor's periphery although the central portion remaining low in density. A few cases exhibited type C pattern, which was a mixture of types A and B. Type A was found essentially in primary liver cancer, and types B and C in secondary liver cancer. Thus, the CT pattern was found to be useful for differential diagnosis. For a sufficient therapeutic effect, 0.08 ml of Smancs/Lpd per cm2 of the maximal CT cross-section of the tumor area was found to be necessary. As a routine protocol after Smancs/Lpd administration, CT scanning was recommended for primary liver cancer initially at 1 week and then once every month. Secondary liver cancer required more frequent CT follow-ups after the administration (on the third day, after 1 and 2 weeks, and every month) due to relatively rapid disappearance of the stain than in the primary liver cancer.

Aged↗
PubMed2005

Differential use of image enhancement techniques by experienced and inexperienced observers.

Full-field digital mammography (FFDM) systems are currently being used to acquire mammograms in digital format, but digital displays are less than ideal compared to traditional film-screen display. Certain physical properties of softcopy displays [e.g., modulation transfer function (MTF)] are less than optimal compared to film. We developed methods to compensate for some of these softcopy display deficiencies, based on careful physical characterization of the displays and image-processing software. A series of 100 FFDM and 60 digitized images was shown to six observers-half experienced (mammographers) and half inexperienced (radiology residents). The observers had to decide if a mass or microcalcification cluster was present and classify it as benign or malignant. A window could be activated that brought the image detail within the window to full resolution and corrected for the nonisotropic MTF of the Cathode Ray Tube (CRT) display. Experienced readers had better diagnostic performance and took less time to view the images. Experienced readers used window/level more than inexperienced readers, but inexperienced readers used magnification and the MTF compensation tool more often. Use of the magnification and the MTF tool increased reader decision confidence. Experienced and inexperienced readers use image-processing tools differently, with certain tools increasing reader confidence. Understanding how observers use image-processing tools may help in the development of better and more automated user interfaces.

Analysis of Variance↗
PubMed1995

[A method of image enhancement in the use of hydrosoluble uro-angiographic contrast media].

The radiographic contrast, when using hydrosoluble uro-angiographic contrast media, depends on several factors. A phantom and a new method are proposed to assess and optimize the contrast. The phantom allows to simulate three pseudovessels with diameter of 2 mm, 5 mm, and 10 mm, placed in a water-equivalent layer of 20/cm thickness. The phantom is exposed to a photon beam produced by a conventional X ray tube, and the images are obtained using conventional screen film system. The aim of the study is to assess the radiographic contrast between the vessel and the background when modifying the optical density of the radiograph (by different settings of the mAs switching), the X-ray tube high voltage and the diameter of the vessels; the contrast was studied with four different contrast media (Uromiro 24%, Conray 36%, Iopamiro 300 and Iomeron 400) and three X-ray tube high voltages (60 kV, 80 kV, 100 kV). The curve fitting the contrast as a function of the optical density of the background (in each condition of high voltage, diameter of the vessel and contrast media used) is a parabola. A quite narrow distribution of abscissas of the maxima of the parabolas was found, ranging from the minimum optical density 1.21 in the case of 100 kV high voltage and 2 mm diameter to the maximum optical density 1.58 in the case 60 kV and 10 mm. The mean value (1.40) is proposed as the optical density of the background optimizing the contrast according to the screen-film system used. In conclusion, the authors suggest to optimize the use of contrast media, trying to obtain radiographs with an optical density approaching the optimal value in any clinical situation. Therefore tables of the settings of the X-ray tube and generator are required; the tables must take into account the main parameters influencing the settings, such as the source-film distance, the water-equivalent thickness of the patient and the film-screen system used.

Angiography↗
PubMed2002

Sonographic examination of the oral phase of swallowing: bolus image enhancement.

PURPOSE: The purpose of this study was to evaluate the ability of 4 liquid boluses to enhance pixel brightness and the ease with which the boluses could be identified during the sonographic evaluation of oral swallowing in healthy young adults. METHODS: Ten healthy adult volunteers (5 men and 5 women), ranging in age from 21 to 31 years, underwent sonographic evaluation of the oral phase of swallowing while sitting in their usual feeding position. We compared the ability of the 4 following liquids to improve sonographic visualization of swallowing with that of water: a carbonated cola beverage, 5.0 ml of Thick-It in 120 ml of water, 2.5 ml of Thick-It in 120 ml of water, and 7.5 ml of confectioners' sugar in 120 ml of water. Water was used as a control. In each case, 5 ml of the liquid was introduced into the subject's oral cavity using a syringe, and the subject was instructed to swallow. Digitized still images and recorded video sequences of sonographic examinations of the swallowing were analyzed. The brightness of the bolus image on selected digitized video frames was measured digitally using Image Analyst software. Pixel brightness within selected regions of interest for each of the test liquids was statistically compared with that for water. Seven clinicians rated the visualization of each test liquid and water on paired sonographic videotape sequences. These ratings and the level of agreement between them were statistically tested. RESULTS: Only the carbonated cola beverage demonstrated statistically greater pixel brightness than that of water on digitized video frames (p = 0.01), whereas both cola (with a moderate inter-rater agreement, kappa = 0.50) and 5.0 ml Thick-It mixed with 120 ml of water (with a fair inter-rater agreement, kappa = 0.24) were significantly better visualized on sonographic video sequences. CONCLUSIONS: The digital still-frame analysis confirmed the clinicians' ratings of bolus visualization on real-time sonography, but dynamic sonography is more important than still frames in assessing sonographic swallow media because the dynamic images more closely parallel what is seen in clinical practice. Future investigations of sonographic contrast agents for use in the examination of the oral phase of swallowing should use both static digital (still-frame) and dynamic (real-time) assessment methods, as well as expert reviewers.

Adult↗
PubMed1993

Anal endosonography for recurrent anal fistulas: image enhancement with hydrogen peroxide.

Anal endosonography is a new technique that is useful in the preoperative assessment of patients with anal fistulas. Endosonographic images are created by the reflection of sound waves from the interfaces between tissues of varying densities. In order to accentuate tissue interface layers at the level of the fistula tract, we introduced hydrogen peroxide into the fistula tract through the external opening during anal ultrasonography in two patients with recurrent anal fistula. Hydrogen peroxide injection resulted in hyperechoic imaging of the preinjection hypoechoic horseshoe fistula tract. Endosonographic findings were confirmed at the time of surgery in both patients. We conclude that hydrogen peroxide enhancement of the fistula tract is a simple, effective, and safe method of improving the accuracy of endoanal ultrasound assessment of recurrent anal fistula.

Endoscopy, Gastrointestinal↗
PubMed1994

[Pelvimetry using various magnetic resonance tomography techniques vs. digital image enhancement radiography: accuracy, time requirement and energy exposure].

In 50 patients with suspected or proven cephalo-pelvine disproportion pelvimetry was performed with MR-tomography using a gradient-echo-sequence (FLASH 2D) before or after labour. Results were compared with measurements using digital radiography. In principle, both methods are exchangeable. The sagittal pelvic in- and outlet bispinous diameters are well reproducible. On the other hand, the transverse pelvic inlet and the distance between the ischiatic tubera are not so reliably reproduced. The accuracy of measurement does not depend on individual pelvic distances. Critical statistical analysis demonstrates, that in the worst case differences between the two methods might become unacceptable. Our results indicate two major reasons: 1. there are interobserver problems which cannot be neglected, and 2. the anatomical definition of referential landmarks for the measurements is unsafe. In 10 volunteers, a comparison was made between a T1-weighted spin-echo sequence (SE), a fast gradient echo sequence (FLASH-2D) and an ultrafast gradient echo technique (Turbo-FLASH). For the examination techniques presented here, the high-frequency exposure load or specific absorption rate (SAR loc and SAR total) is below the values permitted by the German Federal Health Bureau (Bundesgesundheitsamt). Whereas the exposure load in case of spin-echo takes (SE) is 22fold higher than with the gradient echo technique (GHE), the load values of ultra-fast GE (usGE) are only about 16% of the 2D-FLASH sequence or about 0.007% of SE. The difference in image quality does not affect the accuracy of measurement.

Adolescent↗
PubMed1993

Microbubble image enhancement and pericardiocentesis.

When performing pericardiocentesis, if blood-stained fluid is aspirated, one must ensure that the aspirating needle is not within one of the cardiac chambers. To clarify the position of the needle some contrast material may be injected using X-ray screening and for this reason pericardiocentesis is often performed in the catheter laboratory, particularly if the effusion is small, loculated or the heart is in an unusual position. Ultrasound immaging is now commonly used to guide the aspirating needle and if blood-stained fluid is withdrawn we reinject a few millilitres and this outlines the space from which the fluid is withdrawn with microbubbles. This modification of ultrasound immaging adds to the safety of the procedure and allows difficult procedures to be carried out in the ward or intensive care unit, where X-rays screening is not easily available.

Adolescent↗
PubMed1991

Exposure rates in high-level-control fluoroscopy for image enhancement.

High-level fluoroscopic boost options that exceed conventional exposure limits are available as a means of reducing quantum mottle during angiography. Federal law does not specify exposure limits for such high-level controls but requires specific means of activation to safeguard against inadvertent use. The American Association of Physicists in Medicine recently recommended that high-level exposure rates not exceed 2.58 mC/kg/min (10R/min). At six institution surveyed, maximum exposure rates ranged from 5.42 to 24 mC/kg/min (21-93 R/min). Activation of high-level capability varied from a simple foot switch to a keyed interlock requiring a second operator to engage. There appears to be no industry coherence in high-level control exposure limits as yet, although the Center for Devices and Radiological Health recently initiated an investigatory program.

Environmental Exposure↗
PubMed1996

Effect of the rate of gadopentetate dimeglumine administration on abdominal vascular and soft-tissue MR imaging enhancement patterns.

PURPOSE: To delineate dynamic gadopentetate dimeglumine enhancement profiles within the abdomen as a guide to improve gadolinium-enhanced magnetic resonance (MR) angiography. MATERIALS AND METHODS: Fifteen patients (eight women, seven men; aged 19-80 years) underwent fast three-dimensional spoiled gradient-recalled-echo imaging with the keyhole technique during the administration of 0.1 mmol/kg gadopentetate dimeglumine by means of bolus (10-second) injection (n = 5), 60 second injection (n = 5), or slow (120-230-second) pump injection (n = 5). Injection was initiated 10 seconds after imaging began. Regions of interest were constructed within the aorta, inferior vena cava, liver, spleen, renal cortex, muscle, and fat. Inclusion of phantoms of gadopentetate dimeglumine in tubes allowed estimation of intravascular gadolinium concentration. RESULTS: Maximal arterial enhancement occurred with bolus administration; maximal parenchymal organ enhancement, with 60-second injection. Slow pump injection resulted in a longer time to preferential arterial to venous enhancement (120 seconds +/- 14 [+/-standard deviation]) than did bolus (48 seconds +/- 64) or 60-second (88 seconds +/- 39) injections. The peak arterial to venous enhancement ratio was 6.3 +/- 3.3 for the bolus injection, 4.7 +/- 1.6 for the 60-second injection, and 3.3 +/- 1.3 for the slow pump injection. CONCLUSION: The dynamics and magnitude of abdominal vascular and soft-tissue enhancement are affected by the rate of gadopentetate dimeglumine administration.

Abdomen↗
PubMed2005

Overlay of conventional angiographic and en-face OCT images enhances their interpretation.

BACKGROUND: Combining characteristic morphological and functional information in one image increases pathophysiologic understanding as well as diagnostic accuracy in most clinical settings. En-face optical coherence tomography (OCT) provides a high resolution, transversal OCT image of the macular area combined with a confocal image of the same area (OCT C-scans). Creating an overlay image of a conventional angiographic image onto an OCT image, using the confocal part to facilitate transformation, combines structural and functional information of the retinal area of interest. This paper describes the construction of such overlay images and their aid in improving the interpretation of OCT C-scans. METHODS: In various patients, en-face OCT C-scans (made with a prototype OCT-Ophthalmoscope (OTI, Canada) in use at the Department of Ophthalmology (Academic Medical Centre, Amsterdam, The Netherlands)) and conventional fluorescein angiography (FA) were performed. ImagePro, with a custom made plug-in, was used to make an overlay-image. The confocal part of the OCT C-scan was used to spatially transform the FA image onto the OCT C-scan, using the vascular arcades as a reference. To facilitate visualization the transformed angiographic image and the OCT C-scan were combined in an RGB image. RESULTS: The confocal part of the OCT C-scan could easily be fused with angiographic images. Overlay showed a direct correspondence between retinal thickening and FA leakage in Birdshot retinochoroiditis, localized the subretinal neovascular membrane and correlated anatomic and vascular leakage features in myopia, and showed the extent of retinal and pigment epithelial detachment in retinal angiomatous proliferation as FA leakage was subject to blocked fluorescence. The overlay mode provided additional insight not readily available in either mode alone. CONCLUSION: Combining conventional angiographic images and en-face OCT C-scans assists in the interpretation of both imaging modalities. By combining the physiopathological information in the angiograms with the structural information in the OCT scan, zones of leakage can be correlated to structural changes in the retina or pigment epithelium. This strategy could be used in the evaluation and monitoring of patients with complex central macular pathology.

Choroid Diseases↗