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PubMed2003

Radiography of rabbit articular cartilage with diffraction-enhanced imaging.

Articular cartilage of synovial joints is not visible with conventional X-ray imaging. Hence, the gradual degeneration and destruction of articular cartilage, which is characteristic of degenerative joint diseases, is only detected at a late stage when the cartilage is lost and the joint space that it once occupied narrows. The development of an X-ray imaging technique that could detect both the degenerative cartilage and bone features of joint diseases is of special interest. Here we show, for the first time, that a high-contrast imaging technique, diffraction-enhanced X-ray imaging (DEI), allows the visualization of articular cartilage of both disarticulated and articulated rabbit knee joints. Furthermore, a single cartilage lesion can be visualized within an intact joint. The results suggest that DEI has the potential to be of use in the study of cartilage degeneration.

Animals↗
PubMed1995

[MR imaging of infected spondylodiskitis: interval signal change in vertebral body (including enhanced image of vertebral body)].

A retrospective evaluation of MRI was carried out in 22 patients with spondylodiskitis. Low signal intensity on T1-weighted images and high or low signal intensity on T2-weighted images were observed. Sixteen patients underwent follow-up examinations after the initial examination. Various signal changes in the vertebral body were recognized. The longer the period of follow-up, the less abnormal the signal intensity became on both T1- and T2-weighted images. Several cases showed no change in signal intensity. In all of 17 patients re-examined after injection of Gd-DTPA, infected vertebral bodies were enhanced. We classified the enhancing patterns of infected vertebral bodies in three types: A) homogeneous, B) homogeneous with strong enhancement adjacent to the end plate, C) inhomogeneous. Pyogenic spondylodiskitis tended to show patterns A or B, and tuberculous spondylodiskitis pattern C. The enhancement effect disappeared after normalization or remission of laboratory findings. In two cases, the enhancement effect remained even after laboratory findings became normal. Contrast MRI was useful for understanding infectious state.

Adolescent↗
PubMed1990

Video enhanced imaging of the fluorescent Na+ probe SBFI indicates that colonic crypts absorb fluid by generating a hypertonic interstitial fluid.

Extracellular accumulation of Na+ detected by video-enhanced microscopic imaging of the impermeant fluorescent probe SBFI confirms the view that colonic crypts produce a hypertonic ascorbate ca 1000 mOsm.kg-1, thereby generating a large osmotic pressure across the crypt wall. This creates a high fluid tension within the crypt lumen, sufficient to dehydrate faeces. When bathed in Tyrode the SBFI.Na+ fluorescence indicates a [Na+] ca 750 mM within the interstitial space of metabolizing rat descending colon. There is no evidence of interstitial Na+ accumulation in octanol (2 mM) or in rabbit colon incubated with 1.0 mM ouabain and no evidence of Na+ secretion via the crypt lumen during absorption.

Animals↗
PubMed1999

Improved echocardiographic delineation of left ventricular thrombus with the use of intravenous second-generation contrast image enhancement.

Transthoracic echocardiography is the most widely used diagnostic test for left ventricular (LV) thrombus, which must be distinguished from other intraventricular structures and image artifacts. To determine whether second-generation intravenous echocardiographic contrast agents provide better delineation of LV thrombus, we reviewed the results of 2-dimensional echocardiographic studies that were performed in 409 patients over a 1-year period to detect LV thrombus. Studies of 190 (46%) patients were interpreted as nondiagnostic for this purpose, of which 48 patients underwent an additional study after intravenous injection of 0.5 to 2 mL of human albumin microspheres within 1 to 4 days. In 43 (90%) of these 48 patients the contrast-enhanced study was definitive and diagnostic for either the presence or absence of an LV thrombus (P <.0001). Of the initial total of 409 patients, 81 had been studied at the bedside in intensive care units. The bedside studies were nondiagnostic for LV thrombus in 51 (63%) of these 81 patients. Of these 51 patients, 14 underwent additional imaging with contrast enhancement, and the contrast-enhanced images became diagnostic (P =. 004) in 11 (79%) of them. Thus intravenous contrast image enhancement improves the diagnostic yield of echocardiography in patients in whom initial images are nondiagnostic for LV thrombus.

Albumins↗
PubMed2004

Determining the extent to which delayed-enhancement images reflect the partition-coefficient of Gd-DTPA in canine studies of reperfused and unreperfused myocardial infarction.

MRI after a constant infusion (CI) of Gd-DTPA has been used to identify the extent of myocardial infarction (MI). However, Gd-DTPA-enhanced "viability" imaging is more commonly performed with a bolus (for "delayed-enhancement" (DE) imaging). This study sought to determine how image delay time and time postinfarction influence the assessment of necrosis by DE. Both infusion and DE imaging was performed in dogs with reperfused (N = 6) or unreperfused (N = 4) MI. Estimates of the partition-coefficient of Gd-DTPA (lambda) with DE were compared with those calculated after 60 min of infusion, and the comparisons were repeated until 4 (reperfused) or 8 (unreperfused) weeks postinfarction. In reperfused animals, the concordance (Rc) between DE and infusion estimates of lambda was > 0.90 for most image delays > 8 min postinjection, for day 0 through week 3, with Rc at day 0 greater than at week 4 (P = 0.022). In unreperfused animals, there was an interaction between image delay time and time postinfarction (P < 0.001): Rc > 0.90 corresponded to longer image delays at week 1 than at weeks 4-8. Therefore, when image delays are selected appropriately, DE images can strongly reflect lambda and identify irreversibly injured myocardium.

Analysis of Variance↗
PubMed1993

[Non-linear models for real time image processing and their applications in image enhancement, surface area determination and volume visualization].

This paper presents non-linear filter models that are suitable for real-time operations. The requirements imposed on these models by ultrasonic imaging are discussed. In particular, we study the characteristics of temporal filtering in cardiac imaging. Non-linear filter models incorporating these requirements are presented and compared with filtering schemes traditional in ultrasonic imaging. Furthermore, we illustrate how these filter models can be utilized to improve the quality and noise tolerance of automatic, real-time area detection algorithms. Finally, we present results from a 3D ultrasonic study of a foetus. The experiments illustrate how non-linear processing can increase the clinical information content that can be extracted from such investigations.

Body Surface Area↗
PubMed1999

Control portal images enhancement.

The general aim of our study is the patient setup verification using control portal images during the treatments. The main problem of the control portal images processing is their poor quality. We investigated a way of improving the image quality in order to allow a segmentation stage. Four items were studied for this purpose: the presence of distortion, the background gradient of intensity correction, the noise reduction, and the image restoration. The absence of significant distortion was checked with a grid pattern phantom. The background correction was performed by the subtraction from the original image of a smoothed version of this image. We tested 14 noise reduction methods. The most appropriate for our images is the truncated average. Four restoration techniques were compared. The Maximum a Posteriori algorithm is the most efficient. For all the imaging systems, the energies, and the anatomical zones tested an important improvement in anatomic detail was apparent. For example, the SNR of a SRI-100 pelvis image (4 monitor units at 10 MV), went up from 0.97 to 20.06 after enhancement. The image quality improvement will facilitate or enable the segmentation of the control portal images. It is the first step in the patient setup verification.

Humans↗
PubMed2006

Focal liver masses: enhancement patterns on contrast-enhanced images--concordance of US scans with CT scans and MR images.

PURPOSE: To assess prospectively the concordance of enhancement patterns of focal liver masses on contrast material-enhanced ultrasonographic (US) scans with patterns on contrast-enhanced computed tomographic (CT) scans or magnetic resonance (MR) images. MATERIALS AND METHODS: This study was approved by the institutional review board; patients gave informed consent. Contrast-enhanced US and contrast-enhanced CT or MR imaging were performed in 135 patients (62 men, 73 women; mean age, 51 years) with 144 confirmed liver masses. Masses included 49 hepatocellular carcinomas, 13 metastases, 30 hemangiomas, 41 lesions of focal nodular hyperplasia, and 11 others. Randomized image sets from each modality were shown independently to three blinded readers, who answered identical questions about enhancement of the lesion and liver in the arterial and portal venous phases and changes with time. Concordance for modalities was calculated from answers of readers and consensus answers between readers, with 95% confidence intervals (CIs). The kappa values were calculated for interreader agreement. RESULTS: Features of arterial phase enhancement showed concordance of more than 76% for modalities. The highest concordance of 92% (132 of 144), with 95% CI of 86% and 95% (kappa>0.84), was for the presence of peripheral pools and centripetal progression. Concordance in the portal venous phase was lower, with agreement for predominant enhancement of the lesion in 61% (86 of 142), with 95% CI of 52% and 68% (kappa>0.83). Portal venous phase washout occurred in 75% (106 of 142), with 95% CI of 67% and 81% (kappa>0.81). The majority of discordances were for malignancies for which only US depicted no sustained enhancement in the portal venous phase. CONCLUSION: US shows high concordance with CT or MR imaging, especially for the arterial phase. Discordance in the portal venous phase may reflect the tendency of CT and MR contrast agents, unlike microbubbles, to diffuse into interstitium.

Adult↗
PubMedDate not supplied

Comparison of enhancement, image quality, cost, and adverse reactions using 2 different contrast medium concentrations for routine chest CT on 16-slice MDCT.

OBJECTIVE: To evaluate the degree of enhancement and image quality of chest computed tomographic (CT) examinations on 16-slice multidetector CT using low-concentration [300 milligrams of iodine per milliliter (mg I/mL)] and high-concentration (370 mg I/mL) contrast media; to assess the impact on cost and adverse reactions of the use of high-iodine concentration contrast medium. MATERIALS AND METHODS: A total of 100 patients scheduled for routine chest CT examinations were administered nonionic contrast medium of 2 strengths: low-iodine concentration contrast medium (300 mg I/mL) [group A: n = 50; male-female ratio, 28:22; mean age, 58.4 years] and high-iodine concentration contrast medium (370 mg I/mL) (group B: n = 50; male-female ratio, 18:32; mean age, 57.6 years) with a constant amount of iodine (400 mg) injected per kilogram of body weight. Contrast media were injected using a dual injector at 2.5 mL/s followed by a 30-mL saline at 2.5 mL/s. The degree of enhancement was quantified by measuring Hounsfield unit values in different arteries and veins and was also rated on a 5-point scale for qualitative assessment. We also evaluated perivenous contrast-related artifacts. The data were compared using Mann-Whitney U test for both qualitative and quantitative enhancement ratings. A value of less than 0.05 was considered statistically significant. The value was adjusted using Bonferroni correction for statistical significance when multiple comparisons were performed. The difference in cost and the incidence of adverse reactions in both groups were calculated. RESULTS: The mean enhancement values in group B were significantly greater (P < 0.05) than those in group A. The mean Hounsfield units and standard deviation in groups A and B were aorta = 153 +/- 4, 216 +/- 20; pulmonary artery = 147 +/- 10, 208 +/- 20; superior vena cava = 155 +/- 27, 299 +/- 72; and pulmonary vein = 134 +/- 10, 215 +/- 30, respectively. The mean enhancement on a 5-point scale was greater in group B (4.2) than in group A (3.3) (P < 0.01). No significant difference between groups in perivenous artifacts was seen. Up to 5.5% savings in cost resulted from the use of a higher concentration of iodine, with no increase in adverse reactions. CONCLUSIONS: Use of higher-concentration contrast media provides a higher degree of contrast enhancement and image quality for a routine chest CT on a 16-slice multidetector CT. It also contributes to considerable cost savings with no increased risk of adverse reactions compared with low-concentration contrast media.

Adult↗
PubMed2003

Correlation of emmprin expression in vascular endothelial cells with blood-brain-barrier function: a study using magnetic resonance imaging enhanced by Gd-DTPA and immunohistochemistry in brain tumors.

In a previous study, we demonstrated that the expression levels in tumor cells of emmprin (CD147) correlated with the grade of astrocytic tumors. Also, we found that emmprin was expressed in vascular endothelial cells of the non-neoplastic brain and hypothesized that emmprin expression could be associated with normal blood-brain-barrier (BBB) function of vascular endothelial cells. In this study, this possibility was examined in non-neoplastic brain, glioma and metastatic carcinoma tissues by comparing emmprin immunohistochemistry with gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) enhancement of magnetic resonance imaging (MRI), which is a clinical indicator of the BBB function. This study included 10 cases of non-neoplastic brain tissues, 7 of metastatic carcinoma, 7 of diffuse astrocytoma, 4 of anaplastic astrocytoma and 13 of glioblastoma multiforme. In all the cases, MRI with administration of Gd-DTPA was performed. The lesions were resected using the microdissection method with the help of ultrasonography and a neuronavigator. The tissues from Gd-DTPA-enhanced or non-enhanced areas were processed into frozen sections and subjected to immunohistochemistry with anti-emmprin antibody. The expression of emmprin in brain vascular endothelial cells inversely correlated with Gd-DTPA-enhancement of MRI: emmprin was positive in tissues not enhanced by Gd-DTPA and was negative in DTPA-enhanced tissues. Since BBB function presumably remains unimpaired in regions in which MR images are not Gd-DTPA-enhanced, emmprin expression appears to be associated with unimpaired BBB function. This is the first report to demonstrate a possible correlation between emmprin expression and BBB function in humans.

Adult↗
PubMedDate not supplied

Twenty-four-hour thallium-201 late redistribution imaging enhances the detection of myocardial viability after myocardial infarction.

BACKGROUND: Thallium-201 (201Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction. The 3- to 4-h early redistribution imaging has underestimated a considerable part of viable myocardium, while the 24-h late redistribution imaging may enhance the detection of myocardial ischemia/viability, but remains controversial. METHODS: Thirty-eighty patients with myocardial infarction underwent the initial, 3-h, and 24-h redistribution imaging after intravenous injection of 148-185 MBq 201Tl. Image quality analysis was performed using a four-grade model: excellent, good, moderate, and poor. The initial and 3-h images, the initial and 24-h images, and the 3- and 24-h images were compared double-blinded. RESULTS: The 3- and 24-h images showed no significant differences in image quality according to the four-grade model (P=.3580). Out of the 194 abnormal segments based on the initial imaging, 60 (31%) segments improved by at least one grade on the 3-h imaging, while 86 (44%) segments improved by at least one grade on the 24-h imaging. The 24-h late imaging detected more viable myocardium than the 3-h imaging did, with a significant difference (chi2=7.4235, P=.0064). There were 164 abnormal segments on the 3-h imaging, with an average 30% (48) segments improved by at least one grade on the 24-h imaging. There were 134 initial abnormal segments without any improvement on the 3-h imaging. Out of these segments, the 24-h late redistribution imaging detected additional redistribution in 30 segments, taking up 22%. The mean global score on the 3-h imaging significantly decreased compared to that on the initial imaging (t=5.71, P<.0001), and the mean global score on the 24-h imaging further decreased significantly compared to that on the 3-h imaging (t=6.28, P<.0001). CONCLUSIONS: Twenty-four-hour late 201Tl imaging, with satisfactory image quality, enhances the detection of myocardial viability after myocardial infarction.

Adult↗
PubMed1990

Hepatic cirrhosis and hepatitis: MR imaging enhanced with superparamagnetic iron oxide.

Superparamagnetic iron oxide was applied as a reticuloendothelial contrast agent in the diagnosis of cirrhosis and hepatitis in seven patients. Three patients had compensated cirrhosis, and four had active hepatitis. T1- and T2-weighted spin-echo magnetic resonance images were obtained before and 1 hour after the administration of iron oxide. Eight patients without diffuse liver disease served as a control group. Normal liver tissue showed a 75% +/- 9% reduction in signal intensity after the administration of iron oxide, and the liver appeared homogeneously hypointense. Cirrhotic liver tissue showed a smaller response (P less than .05) to iron oxide, with a 52% +/- 13% reduction in liver signal intensity. Inhomogeneous structures could be observed in enhanced images and are thought to represent fibrous bands or regenerating nodules. Liver tissue with active hepatitis showed a markedly reduced response to iron oxide (11% +/- 2%) (P less than .05), and the parenchyma appeared homogeneous. The authors conclude that the uptake of iron oxide particles is inhomogeneously altered in cirrhosis because of structural changes and homogeneously decreased in hepatitis because of functional changes of hepatic parenchyma.

Contrast Media↗
PubMed1998

Image enhancement by noncontrast harmonic echocardiography. Part I. Qualitative assessment of endocardial visualization.

OBJECTIVE: To determine whether harmonic imaging--use of signals with frequencies twice that of the transmitted ultrasound to produce ultrasound images--can improve endocardial border definition in patients who have technically difficult echocardiograms. METHODS: We studied 29 patients with technically difficult echocardiograms (nonvisualization of 2 or more endocardial segments in a 16-segment model). Apical long-axis, four-chamber, and two-chamber images were acquired during fundamental imaging (at 2.0 and 3.5 MHz) and second harmonic imaging (3.5-MHz receive mode) in random order. Images were digitally stored and subsequently reviewed blindly for endocardial segment score (0 = not visualized; 1 = adequate; or 2 = excellent) and overall ranking of image quality (1 [best] to 3 [worst]). RESULTS: Mean endocardial segment score was significantly better (P < 0.0001) for harmonic imaging (1.02 +/- 0.36) than for either fundamental mode (0.49 +/- 0.21 and 0.57 +/- 0.27 for the 2.0- and 3.5-MHz images, respectively). The harmonic images were ranked as better (P < 0.0001) than those of either fundamental mode: harmonic mean rank was 1.07 in comparison with 2.67 and 2.26 for the 2.0- and 3.5-MHz fundamental images, respectively. CONCLUSION: Noncontrast harmonic imaging appreciably enhances endocardial definition in patients with technically difficult echocardiographic studies and significantly improves overall image quality.

Adult↗
PubMed1997

[A new method for imaging intracranial cerebral arteries--3-dimensional transcranial duplex ultrasonography with image enhancement].

AIM: A new data acquisition system for transcranial 3 D-ultrasonography was used. The present study examines the evaluation of intracranial cerebral arteries by 3 D-ultrasound and echo contrast agents in comparison to cerebral angiography. METHODS: Ten patients, who underwent diagnostic cerebral angiography, were examined without knowledge of the angiographic results. Data acquisition through the transtemporal acoustic bone window was performed with a magnetic sensor system to track the spatial orientation of the ultrasound probe while scanning the volume of interest. We used a transcranial duplex system with power mode and stored a 3 D-data set before injection of transpulmonary stable contrast medium and afterwards. RESULTS: Ipsilateral to the transducer anterior cerebral artery (ACA) in 90%, middle cerebral artery (MCA) in 90%, three or more branches of MCA in 60% and posterior cerebral artery (PCA) in 40% were analysed without injecting an echo contrast agent. After the contrast injection ACA, MCA, branches of MCA and PCA in 100% were visible. In 70% of cases the posterior and anterior communicating arteries were visualised only by means of a contrast agent. CONCLUSION: Application of a transpulmonary stable ultrasound contrast agent in combination with 3 D transcranial duplex ultrasonography significantly enhances the visualisation of intracranial arteries.

Adult↗
PubMed2003

MR imaging enhancement patterns as predictors of hemorrhagic transformation in acute ischemic stroke.

BACKGROUND AND PURPOSE: Early parenchymal gadolinium enhancement on T1-weighted MR images is predictive of hemorrhagic transformation (HT) in rodent focal ischemia models, but its value in humans is unknown. We sought to investigate gadolinium enhancement in acute ischemic stroke patients to determine their association with subsequent HT. METHODS: We retrospectively examined 22 patients with ischemic stroke who underwent MR imaging within 4.9 hours (+/-1.4) of symptom onset. Patients receiving intravenous tissue plasminogen activator (tPA) (n = 6) were included. Twenty-one patients underwent repeat MR studies at 48 hours, 13 underwent additional MR imaging at 1 week, and one underwent follow-up head CT at 24 hours. Initial images were analyzed for enhancement patterns (vascular, meningeal, parenchymal). Follow-up T2- and T2*-weighted images were evaluated for hemorrhage. RESULTS: In all patients, initial MR images showed vascular enhancement in the vascular territory of the stroke lesion: 19 with vascular enhancement alone and three with vascular and parenchymal enhancement. All three patients with both enhancement patterns had HT: two large and symptomatic, and one asymptomatic (petechial hemorrhage). They received tPA before MR imaging. None of the patients without early parenchymal enhancement developed symptomatic hemorrhage. Six (32%) patients with vascular enhancement alone had petechial hemorrhage at follow-up imaging. In this limited sample, initial mean volumes on diffusion-weighted images, National Institute of Health Stroke Scale scores, and intervals from stroke onset to imaging did not differ between patients with vascular and parenchymal enhancement versus those with vascular enhancement alone. CONCLUSION: Early parenchymal enhancement of stroke lesions may be a good predictor of subsequent symptomatic HT may help identify patients at risk, especially after thrombolytic therapy.

Aged↗
PubMed2003

Sensitivity and depth penetration of continuous wave versus frequency-domain photon migration near-infrared fluorescence contrast-enhanced imaging.

The development of near-infrared fluorescent contrast agents and imaging techniques depends on the deep penetration of excitation light through several centimeters of tissue and the sensitive collection of the re-emitted fluorescence. In this contribution, the sensitivity and depth penetration of various fluorescence-enhanced imaging studies is surveyed and compared with current studies using continuous wave (CW) and frequency-domain photon migration (FDPM) measurements with planar wave illumination of modulated excitation light at 100 MHz and area collection of reemitted fluorescent light using a previously developed modulated intensified charge-coupled device camera system. Fluorescence was generated from nanomolar to micromolar solutions of indocyanine green (ICG) in a 100 microL volume submerged at 1-4 cm depths in a 1% Liposyn solution to mimic tissue scattering properties. Enhanced depth penetration and sensitivity are achieved with optimal filter rejection of excitation light, and FDPM rejection of background light is not achieved using CW methods. We show the ability to detect as few as 100 fmol of ICG from area illumination of 785 nm light (5.5 mW/cm2) and FDPM area collection of 830 nm fluorescent light generated from 3 cm below the phantom surface. The lowered noise floor of FDPM measurements enables greater sensitivity and penetration depth than comparable CW measurements.

Photons↗
PubMed1997

A new fuzzy logic based image enhancement.

In this paper a new fuzzifier (fh) and a new contrast intensification operator (NINT) have been proposed for the enhancement of computerized tomography (CT) images. The performance of the proposed technique has been compared with an existing fuzzy logic based enhancement technique in terms of a new fuzzy contrast measure. The superiority of the proposed technique has been established.

Fuzzy Logic↗