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At least 559 records · Page 31Linked to original sources
PubMedDate not supplied

A preliminary study of discrimination among the components of small pulmonary nodules by MR imaging: correlation between MR images and histologic appearance.

PURPOSE: To investigate whether magnetic resonance (MR) imaging depicts the internal characteristics of small pulmonary nodules. METHODS: We reviewed MR images of 39 surgically resected pulmonary nodules 3 cm or less and compared the components within the nodules. In 22 malignant nodules, eight histologic components were characterized by signal and enhancement patterns on MR images. RESULTS: MR images obtained from any single sequence discriminated all components in 26 (67%) nodules, whereas the combination of images from various sequences allowed discrimination in 35 (90%). Fourteen of 16 components of aggregated tumor cells showed marked early enhancement. Although fibrotic and necrotic components showed no or slight early enhancement, nine of 10 fibrotic components showed hypointensity and six of seven necrotic components showed hyperintensity on T2-weighted images. Component characterization in eight histologies by MR imaging was possible in 71-100%. CONCLUSION: Our study demonstrated that MR imaging offers the possibility of high tissue-contrast resolution in small pulmonary nodules.

Adenocarcinoma↗
PubMed2004

Effects of lossy image compression on quantitative image analysis of cell nuclei.

OBJECTIVE: To investigate whether statistically significant changes occur in quantitative image analysis of cell nuclei when lossy image compression techniques are used. STUDY DESIGN: Thirty-five stoichiometric, Feulgen-stained samples of rat hepatocytes, human thyroid and ovarian cancer cell nuclei were used. Image analysis was performed by a computerized system that used AutoCyte LINK V1.1.1.56 software (Burlington, North Carolina, U.S.A.) for image acquisition and Zeiss Vision KS 400 V3.0 software (Oberkochen, Germany) for quantitative image analysis. After lossy JPEG compression of acquired images at different quality levels, some densitometric features were selected and measurements performed. RESULTS: We observed that nearly all the standard densitometric features showed statistically significant changes when images were compressed with the lossy JPEG algorithm. However, most invariant densitometric moment features remained free of statistically significant changes. CONCLUSION: The standard densitometric measurements that we used do not tolerate lossy compression. However, analyses using invariant densitometric features may be performed on images compressed with lossy JPEG, resulting in simpler, less expensive systems demanding less network bandwidth.

Animals↗
PubMed1990

[Imaging and the court of law: useful images and useless images].

The expert who review a medical record in a liability suit is required to determine whether the tests performed were necessary and, above all, whether they were adequate. In France, physicians are legally required to use adequate diagnostic and therapeutic means, especially in complicated cases. When this obligation is not fulfilled, the urologist is often held responsible since he or she is in charge of interpreting the tests and drawing final conclusions. Urologists are rarely criticized for performing too many investigations. The urologist is not considered liable for complications that occur during the performance of a necessary test: in this case, the physician who performed the test is legally responsible.

Diagnosis, Differential↗
PubMed1986

Echo shape analysis and image size adjustment on the level of echoes: improvement of parameter-selective proton images.

Parameter-selective imaging for tissue characterization is performed at low magnetic fields (0.24-0.28 T) employing echo trains with a large number of echoes (less than or equal to 50), high-power pulses, and the projection reconstruction method. Preprocessing of the raw echoes is important for the quality of the echo images which are the bases for further evaluation and generation of parameter-selective images. Two new algorithms are implemented in the image preprocessing routine TOMIKON: Echo shape analysis and image size adjustment. Echo shape analysis allows the detection and the removal of spikes in the echo signals to avoid image artifacts. Image size adjustment is performed by expanding and contracting the time basis of the echoes resulting in a size normalization of the echo images, an indispensable condition for generating diffusion images.

Head↗
PubMed2001

Comparison of conventional color Doppler imaging and power doppler imaging for the diagnosis of ovarian cancer: results of a European study.

OBJECTIVE: The purpose of this prospective study was to compare the diagnostic accuracy of conventional color Doppler (CCD) imaging and power Doppler (PD) imaging in the diagnosis of ovarian cancer. METHODS: Six hundred fifty-six consecutive women with adnexal masses scheduled for surgery in two European university departments of obstetrics and gynecology underwent preoperative transvaginal ultrasound. The scanning procedure was the same in the two institutions: after B-mode sonography, a CCD/PD imaging scan was performed before pulsed Doppler evaluation. Using both modalities of color Doppler, malignancy was suspected when arterial flow was visualized in an echogenic portion defined as malignant by B-mode. To avoid the risk of bias due to the absence of blindness of the examiner after the first Doppler evaluation, at one institution 328 consecutive women with an adnexal mass were evaluated using only CCD imaging, whereas at the second institution the ultrasonographic evaluation of the same number of masses was performed using PD imaging, and the results were compared prospectively. RESULTS: The age, the rate of postmenopausal women, and the rate of ovarian cancer were similar in the two institutions. The false-positive rate of B-mode imaging was similar in the two institutions (17 versus 18%), while the false-positive rates of CCD and PD imaging were 4.6 and 7.4%, respectively. Although the overall diagnostic accuracy of two techniques seems comparable, with a similar value of K (0.81 versus 0.84), a significantly lower sensitivity in differentiation of benign from malignant ovarian lesions was found using CCD (87 versus 100%). CONCLUSIONS: At least one of the two Doppler techniques should be used in conjunction with B-mode imaging in order to decrease the false-positive rate of B-mode used alone but CCD imaging showed a higher false-negative rate.

Adult↗
PubMedDate not supplied

Myocardial technetium 99m-labeled sestamibi single-photon emission computed tomographic imaging in the detection of coronary artery disease: comparison between early (15 minutes) and delayed (60 minutes) imaging.

BACKGROUND: Previous studies have demonstrated that there is a "partial" myocardial redistribution of 99mTc-labeled sestamibi (MIBI) between 1 and 3 hours after intravenous injection at stress. The purpose of this prospective study was to compare MIBI single-photon emission computed tomographic (SPECT) imaging performed 15 and 60 minutes after the injection at stress in the detection of coronary artery disease. METHODS AND RESULTS: Thirty-five patients with coronary artery disease (26 underwent coronary angiography and 23 had a positive 201Tl study result) were included in this study. SPECT imaging started 15 minutes after the injection of 25 to 30 mCi MIBI at peak stress (180-degree arc, 32 angles, 25 sec/view, and high-resolution collimator). Patients underwent reimaging at 60 minutes according to the same protocol and with the same gamma camera. A rest study was obtained 75 minutes after the injection of MIBI (25 to 30 mCi) at rest, 48 hours later. Images (divided for a total of 19 segments per patient) were interpreted by two blinded observers for patient diagnosis and segmental comparison. The patient diagnosis was the same for the two protocols: normal = 3, ischemia = 27, and scar = 5. The segmental agreement (kappa = 0.90) was 632/665 (95.0%). The imaging performed at 15 minutes detected normal, ischemia, and scar in 413, 189, and 63 segments, respectively, whereas the imaging performed at 60 minutes detected 422, 180, and 63 segments, respectively (difference not significant). The early and delayed images were placed side by side for subjective comparison of the extent of the defect. Early imaging showed slightly larger defects in six patients, equal defects in 24 patients, and slightly smaller defects in five patients. Ischemic/normal wall ratios were 0.67 +/- 0.16 at 15 minutes and 0.68 +/- 0.15 at 60 minutes. CONCLUSIONS: There is no clinically significant difference between SPECT imaging performed at 15 minutes or 60 minutes after the injection of MIBI at stress. Furthermore, this study showed that it is feasible to obtain good-quality MIBI images even 15 minutes after the injection at stress.

Adult↗
PubMed1994

Thallium-201 reinjection images can identify the viable and necrotic myocardium similarly to metabolic imaging with glucose loading 18F-fluorodeoxyglucose (18FDG)-PET.

We compared the usefulness of 18F-fluorodeoxyglucose (18FDG)-PET with glucose loading and thallium-201 (201Tl) reinjection imaging for determining the viability of the myocardium in 21 patients with an old anterior myocardial infarction. We obtained transaxial views during 201Tl reinjection imaging performed 10 minutes after post-exercise injection of 37 MBq 201Tl. PET imaging with 75 g oral glucose loading was performed 60 min after injection of 148 MBq of 18FDG. Wall motion was evaluated by echocardiography. Excellent 18FDG-PET images were obtained in 19 of 21 subjects in whom plasma glucose levels were below 251 mg/dl. The results of 201Tl reinjection imaging and 18FDG-PET imaging were in agreement in 20 of the 21 subjects. Echocardiography demonstrated hypokinesis or akinesis in segments identified as abnormal in imaging studies. Our results showed that 201Tl reinjection imaging identified the viable and necrotic myocardium similarly to metabolic imaging obtained by 18FDG-PET with glucose loading.

Adult↗
PubMed1999

Electronic imaging impact on image and report turnaround times.

We prospectively compared image and report delivery times in our Urgent Care Center (UCC) during a film-based practice (1995) and after complete implementation of an electronic imaging practice in 1997. Before switching to a totally electronic and filmless practice, multiple time periods were consistently measured during a 1-week period in May 1995 and then again in a similar week in May 1997 after implementation of electronic imaging. All practice patterns were the same except for a film-based practice in 1995 versus a filmless practice in 1997. The following times were measured: (1) waiting room time, (2) technologist's time of examination, (3) time to quality control, (4) radiology interpretation times, (5) radiology image and report delivery time, (6) total radiology turn-around time, (7) time to room the patient back in the UCC, and (8) time until the ordering physician views the film. Waiting room time was longer in 1997 (average time, 26:47) versus 1995 (average time, 15:54). The technologist's examination completion time was approximately the same (1995 average time, 06:12; 1997 average time, 05:41). There was also a slight increase in the time of the technologist's electronic verification or quality control in 1997 (average time, 7:17) versus the film-based practice in 1995 (average time, 2:35). However, radiology interpretation times dramatically improved (average time, 49:38 in 1995 versus average time 13:50 in 1997). There was also a decrease in image delivery times to the clinicians in 1997 (median, 53 minutes) versus the film based practice of 1995 (1 hour and 40 minutes). Reports were available with the images immediately upon completion by the radiologist in 1997, compared with a median time of 27 minutes in 1995. Importantly, patients were roomed back into the UCC examination rooms faster after the radiologic procedure in 1997 (average time, 13:36) than they were in 1995 (29:38). Finally, the ordering physicians viewed the diagnostic images and reports in dramatically less time in 1997 (median, 26 minutes) versus 1995 (median, 1 hour and 5 minutes). In conclusion, a filmless electronic imaging practice within our UCC greatly improved radiology image and report delivery times, as well as improved clinical efficiency.

Adult↗
PubMed1992

Use of ultrasound imaging and fluoroscopic imaging to study gastric retention of enzyme-digestible hydrogels.

Ultrasound and fluoroscopic imaging techniques were used to monitor the gastric retention of enzyme-digestible hydrogels in the canine stomach. When water was present in the stomach, ultrasound imaging was very effective in monitoring the position of the hydrogel in the stomach, solvent penetration into the gel, and the gastric tissue-gel interactions during peristalsis. Rubbery or fully swollen hydrogels appeared as sonolucent objects with ultrasound imaging. Partially swollen hydrogels displayed a sonolucent outer layer due to solvent penetration and a centrally located bright echo resulting from the acoustic impedance mismatch at the glassy/rubbery interface. The degree of gastric tissue-gel interactions during peristalsis was inversely related to the extent of lumenal distention with water. The effectiveness of peristaltic contractions in driving the hydrogel toward the pyloric sphincter increased as the water was emptied from the stomach. In the absence of water, imaging of the gel with ultrasound became difficult. For this reason, gels were loaded with diatrizoate meglumine/sodium diatrizoate to visualize in real-time using fluoroscopic imaging. Fluoroscopic imaging allowed only indirect assessment of the hydrogel movement during peristalsis and the degree of hydrogel swelling. The gastric retention of the hydrogel under fasted conditions was influenced by the degree of gel deformation in response to peristaltic contractions. Hydrogels with a low degree of deformation during peristalsis showed long gastric retention times. The utilization of ultrasound imaging and fluoroscopic imaging for monitoring dynamic events in the stomach provided information on hydrogel properties which are important to gastric retention. The use of these imaging techniques in the development of long-term oral drug delivery systems is described.

Administration, Oral↗
PubMed1991

A method to analyze 2-dimensional daily radiotherapy portal images from an on-line fiber-optic imaging system.

On-line radiotherapy imaging systems allow convenient treatment verification and generate a wealth of data. Quantitative analysis of data will provide important information about the nature of treatment variations. Using an inhouse fiber-optic imaging system to acquire daily portal images for five patients, we have developed a method to analyze the cumulative positional variation of blocks in the 2-dimensional images. For each beam arrangement used to treat a particular patient, a reference portal image was established. All other images for that patient were registered with respect to the anatomical landmarks visible on the reference image. Two-dimensional frequency distributions describing the overlap of the blocks during the course of treatment were then calculated and superimposed on the reference image. Results of the analysis show positional and quantitative information about the daily variation in block placement, and appeared to be site-dependent. Long term verification studies using on-line imaging systems will be important in the understanding of treatment uncertainties.

Radiology Information Systems↗