Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “imaging”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2006

Correction of an image size difference between positron emission tomography (PET) and computed tomography (CT) improves image fusion of dedicated PET and CT.

AIM: Clinical work in software positron emission tomography/computed tomography (PET/CT) image fusion has raised suspicion that the image sizes of PET and CT differ slightly from each other, thus rendering the images suboptimal for image fusion. The aim of this study was to evaluate the extent of the relative image size difference between PET and CT and the impact of the correction of this difference on the accuracy of image fusion. METHODS: The difference in real image size between PET and CT was evaluated using a phantom study. Subsequently, 13 patients with cancer in the head/neck area underwent both CT and [(18)F]fluorodeoxyglucose PET in a custom-made mask for external beam radiotherapy, with multimodality markers for positional reference. The image size of PET relative to CT was determined by evaluating the distances between the markers in multiple directions in both scans. Rigid-body image fusion was performed using the markers as landmarks, with and without correction of the calculated image size difference. RESULTS: Phantom studies confirmed a difference in real image size between PET and CT, caused by an absolute error in PET image size calibration. The clinical scans demonstrated an average relative difference in image size of 2.0% in the transverse plane and 0.8% along the longitudinal axis, the PET images being significantly smaller. Image fusion using original images demonstrated an average registration error of 2.7 mm. This error was decreased to 1.4 mm after size correction of the PET images, a significant improvement of 48% (P<0.001). CONCLUSIONS: A significant deviation in PET image size may occur, either as a real image size deviation or as a relative difference from CT. Although possibly not clinically relevant in normal diagnostic procedures, correction of such a difference benefits image fusion accuracy. Therefore, it is advisable to calibrate the PET image size relative to CT before performing high-accuracy rigid-body image fusion.

Algorithms↗
PubMed2003

Conventional radiography, rapid MR imaging, and conventional MR imaging for low back pain: activity-based costs and reimbursement.

PURPOSE: To incorporate personnel and equipment use time in an activity-based cost comparison of conventional radiography and conventional and rapid magnetic resonance (MR) imaging for low back pain (LBP). MATERIALS AND METHODS: At each of four Seattle Lumbar Imaging Project (SLIP) sites, patients were randomized to undergo conventional radiography or rapid MR imaging of the lumbar spine. For sample SLIP patients and for similar non-SLIP patients undergoing conventional lumbar spine MR imaging as usual care in calendar year 2000, measured imaging room use and technologist and radiologist times were multiplied by costs per minute of standard equipment acquisition, personnel compensation, and related expenses. Resulting provider-perspective costs and Seattle area Medicare reimbursements for conventional MR imaging and radiography for calendar year 2001 were used to estimate future "normative" reimbursement for rapid MR imaging. RESULTS: For 23 conventional radiography, 27 rapid MR imaging, and 38 conventional MR imaging examinations timed in calendar year 2000, all rapid MR imaging times exceeded those of conventional radiography but were less than those of conventional MR imaging. All 0.3- and 0.35-T MR imaging room and technologist times exceeded those for 1.5-T MR imaging. Average costs (in 2001 dollars) were $44 for conventional radiography, 126 US dollars for 1.5-T rapid MR imaging, 128 US dollars for 0.3-0.35-T rapid MR imaging, 267 US dollars for 1.5-T conventional MR imaging, and 264 US dollars for 0.3-0.35-T conventional MR imaging. Conclusions regarding cost differences between conventional radiography and rapid MR imaging were robust to plausible parameter value changes evaluated in sensitivity analyses. Conventional radiography reimbursement was 44 US dollars. Applying the ratio of reimbursement (620 US dollars) to costs (264-267 US dollars) for conventional MR imaging to rapid MR imaging costs predicted reimbursement of 292-300 US dollars for the new modality. CONCLUSION: Times and costs for rapid MR imaging are roughly three times those for conventional radiography but about half those for conventional MR imaging for LBP. While current conventional radiography costs exceed reimbursement, current conventional MR and projected rapid MR imaging reimbursements exceed costs.

Cost-Benefit Analysis↗
PubMed2006

Image-fusion of MR spectroscopic images for treatment planning of gliomas.

1H magnetic resonance spectroscopic imaging (MRSI) can improve the accuracy of target delineation for gliomas, but it lacks the anatomic resolution needed for image fusion. This paper presents a simple protocol for fusing simulation computer tomography (CT) and MRSI images for glioma intensity-modulated radiotherapy (IMRT), including a retrospective study of 12 patients. Each patient first underwent whole-brain axial fluid-attenuated-inversion-recovery (FLAIR) MRI (3 mm slice thickness, no spacing), followed by three-dimensional (3D) MRSI measurements (TE/TR: 144/1000 ms) of a user-specified volume encompassing the extent of the tumor. The nominal voxel size of MRSI ranged from 8 x 8 x 10 mm3 to 12 x 12 x 10 mm3. A system was developed to grade the tumor using the choline-to-creatine (Cho/Cr) ratios from each MRSI voxel. The merged MRSI images were then generated by replacing the Cho/Cr value of each MRSI voxel with intensities according to the Cho/Cr grades, and resampling the poorer-resolution Cho/Cr map into the higher-resolution FLAIR image space. The FUNCTOOL processing software was also used to create the screen-dumped MRSI images in which these data were overlaid with each FLAIR MRI image. The screen-dumped MRSI images were manually translated and fused with the FLAIR MRI images. Since the merged MRSI images were intrinsically fused with the FLAIR MRI images, they were also registered with the screen-dumped MRSI images. The position of the MRSI volume on the merged MRSI images was compared with that of the screen-dumped MRSI images and was shifted until agreement was within a predetermined tolerance. Three clinical target volumes (CTVs) were then contoured on the FLAIR MRI images corresponding to the Cho/Cr grades. Finally, the FLAIR MRI images were fused with the simulation CT images using a mutual-information algorithm, yielding an IMRT plan that simultaneously delivers three different dose levels to the three CTVs. The image-fusion protocol was tested on 12 (six high-grade and six low-grade) glioma patients. The average agreement of the MRSI volume position on the screen-dumped MRSI images and the merged MRSI images was 0.29 mm with a standard deviation of 0.07 mm. Of all the voxels with Cho/Cr grade one or above, the distribution of Cho/Cr grade was found to correlate with the glioma grade from pathologic finding and is consistent with literature results indicating Cho/Cr elevation as a marker for malignancy. In conclusion, an image-fusion protocol was developed that successfully incorporates MRSI information into the IMRT treatment plan for glioma.

Brain Neoplasms↗
PubMed1999

Improvement of the fluorine-18 fluorodeoxyglucose images in simultaneous F-18 FDG/Tc-99m collimated spect imaging.

Collimated F-18 FDG SPECT imaging has been shown to be an acceptable alternative to F-18 FDG PET imaging for evaluating injured but viable myocardium. Ultra-energy (UHE) imaging is usually performed in simultaneous F-18 FDG/Tc-99m MIBI studies. The main limitations of this technique are degradation of the Tc-99m MIBI images due to F-18 downscatter to the Tc-99m window, and loss of resolution in Tc-99m images caused by using a UHE rather than a low-energy collimator. The quality of F-18 images has not been addressed. In our clinical and phantom studies we have found that F-18 images are inferior to simultaneously acquired Tc-99m MIBI images. This paper compares two correction methods for F-18 FDG images in a realistic cardiac phantom study. One approach is subtractive scatter correction, which employs a third 410 keV energy window image to estimate scatter. The other approach is based on restoration. The phantom acquisition was performed with 7.2 MBq of F-18 and 22.2 MBq of Tc-99m injected into the left ventricular (LV) wall. Three inserts, 3 cm, 2 cm, and 1 cm in diameter, were placed in the LV wall to simulate infarcts. Circumferential profiles were drawn from three successive short-axis slices and compared with true phantom data. The differences were calculated as root-mean-square error (rmse). Scatter correction improved rmse only 4.5 +/- 0.3%, while restoration improved rmse 16.1 +/- 0.4%, when compared with raw data. The same differences, measured as rmse, were 9.5 +/- 0.5, 6.8 +/- 0.4, and 5.1 +/- 0.5 for raw, scatter corrected, and restored F-18 data, respectively, when compared with Tc-99m window 140 keV data. The amount of noise, measured as root-mean-square % (rms%) was 5.3 +/- 0.5% for the Tc-99m image, 4.9 +/- 0.7% for the F-18 restored image, 6.2 +/- 0.6% for the raw F-18 image, and 6.5 +/- 0.9% for the scatter corrected F-18 image. The contrast measured for 2 cm and 3 cm inserts was 0.17 +/- 0.07 and 0.26 +/- 0.06 for F-18 raw data, 0.19 +/- 0.08 and 0.29 +/- 0.06 for the scatter corrected F-18 image, and 0.28 +/- 0.06 and 0.43 +/- 0.07 for the restored F-18 image. The contrast was 0.20 +/- 0.07 and 0.46 +/- 0.05 for the Tc-99m 140 keV window image. The restoration approach provided F-18 images of better contrast and detectibility than uncorrected or scatter corrected F-18 images. Restored F-18 images match better with the simultaneously acquired Tc-99m images.

Biophysical Phenomena↗
PubMedDate not supplied

Evaluation of small pulmonary arteries by 16-slice multidetector computed tomography: Optimum slab thickness in condensing transaxial images converted into maximum intensity projection images.

OBJECTIVE: The purpose of this study was to determine the optimal slab thickness for condensing transaxial images into maximum intensity projection (MIP) images in the evaluation of small pulmonary arteries using 16-slice multidetector-row computed tomography (MDCT). METHODS: Helical computed tomography (CT) scans were obtained from lung apices to bases using 16-slice MDCT [120 kV(peak), 180 mA, beam width of 10 mm, beam pitch of 1.375, and reconstruction thickness of 1.25 mm] in 29 patients suspected of having a pulmonary embolism. Four kinds of image series (1.25-mm thick original transaxial source images and 3 kinds of reconstructed images using the MIP technique with slab thicknesses of 2.5 mm, 5 mm, and 10 mm) were obtained from each patient and forwarded to monitors of a picture archiving and communication system for analysis by 2 independent observers. The observers recorded the name of the segmental (20 total; 10 in each lung) and subsegmental (40 total; 20 in each lung) arteries that were traceable in each image series. Image quality of the 4 image types were graded into 5 scales based on their degree of vascular opacification, the sharpness of the vascular margins of the contrast-enhanced CT angiograms, and the visibility of lung parenchyma (excellent [5] to nondiagnostic [1]) and compared. RESULTS: In both the 1.25-mm thick original transaxial and 2.5-mm thick MIP images, a higher percentage of subsegmental arteries was traceable (91.3% [2119/2320 observations] and 87.2% [2023/2320 observations], respectively; P <0.05) than in the 5-mm and 10-mm thick MIP images (66.4% [1540/2320] and 40.5% [940/2320], respectively). No statistically significant difference was observed between the 1.25-mm thick transaxial and 2.5-mm thick MIP images in this respect. Image quality of 2.5-mm thick MIP images was superior to that of the 5-mm and 10-mm thick MIP images (P < 0.0001). No statistically significant difference was found between the scores of the image quality of the 1.25-mm thick original transaxial images and the 2.5-mm thick MIP images. CONCLUSION: After reducing the image number by one half, 2.5-mm thick MIP images using 16-slice MDCT are found to provide satisfactory images, which are comparable to 1.25-mm thick transaxial images for the analysis of subsegmental pulmonary arteries in patients suspected of pulmonary embolism.

Adult↗
PubMed1999

[11C]flumazenil PET: activity images versus parametric images for the detection of neocortical epileptic foci.

UNLABELLED: [11C]flumazenil (FMZ) imaged with PET allows the computation of parametric images of both tracer influx (K1) and volume of distribution (VD). The VD images, which allow visualization of a quantitative measure of benzodiazepine receptor binding, are reported to have high sensitivity and specificity for the delineation of epileptic foci. However, the clinical feasibility of this method is compromised by the necessity of arterial blood sampling. We therefore compared the performance of parametric VD images against simple FMZ activity images for the detection of neocortical epileptic foci. METHODS: FMZ PET data from 7 children with extratemporal lobe epilepsy (mean age [+/- SD] 9.8+/-4.4 y) and 6 healthy adult volunteers (mean age [+/- SD] 40+/-8 y) were analyzed using a semiautomated analysis algorithm. FMZ activity images and parametric VD images were analyzed for asymmetry with cutoff thresholds of 8%, 10% and 12%. RESULTS: The time frame between 10 and 20 min after injection represented overall the best agreement between FMZ activity and VD images independent of the threshold. The normal asymmetry in VD images was determined as 6.4%+/-1.4% and was significantly higher in the FMZ activity images (7.6%+/-1.4%, P = 0.001). Increasing the cutoff threshold resulted in a significant decrease in the area defined as abnormal in both the VD and the FMZ activity images. Abnormalities defined in FMZ activity images identified additional brain regions as abnormal at the 8% threshold, but there was good agreement with VD images at the 10% asymmetry threshold. In those regions where abnormalities in VD and FMZ activity images were not matched, the asymmetry indices obtained from K1 images were significantly higher than those derived from the VD images (P = 0.01). CONCLUSION: Differences between VD and activity images above the 8% threshold are mainly due to K1. Abnormalities defined in FMZ activity images using a threshold of 10% agree well with those obtained from parametric VD images, indicating that activity images obtained from the time frame of 10-20 min are essentially equivalent to VD images with regard to detection of regions of abnormality for seizure focus localization.

Adult↗
PubMedDate not supplied

Conspicuity of normal and pathologic female pelvic anatomy: comparison of gadolinium-enhanced T1-weighted images and fast spin echo T2-weighted images.

PURPOSE: Our goal was to compare the conspicuity of normal and pathologic female pelvic anatomy between gadolinium-enhanced T1-weighted images and fast SE (FSE) T2-weighted images. METHOD: In 48 consecutive female patients, pre- and postenhanced T1-weighted images were compared with FSE T2-weighted images acquired with a phased array coil. Normal zonal anatomy (ZA) and pathologic abnormalities in gadolinium-enhanced T1-weighted images were rated as increased, decreased, or without change in conspicuity as compared with FSE T2-weighted images. RESULTS: The normal ZA of the uterine corpus on T1-weighted images showed a decrease in conspicuity in 93% of patients and an increase in 7% compared with FSE T2-weighted images. Conspicuity of cervical ZA on T1-weighted images was decreased in 86%, increased in 6%, and without change in 8% as compared with FSE T2-weighted images. ZA of the vagina on T1-weighted images was decreased in 94% and increased in 6% as compared with FSE T2-weighted images. On T1-weighted images, ovarian anatomy delineation was decreased in 95% and increased in 5% as compared with FSE T2-weighted images. Conspicuity of malignant pathologic abnormalities on T1-weighted images was decreased in 81%, increased in 11%, and without change in 8% as compared with FSE T2-weighted images. In patients with benign disease, conspicuity on T1-weighted images was decreased in 92%, increased in none, and without change in 8% as compared with FSE T2-weighted images. The p value for all categories was < 0.0001. CONCLUSION: Conspicuity of both normal and pathologic anatomy was significantly decreased on enhanced T1-weighted images. The use of gadolinium cannot replace T2-weighted scans for delineation of anatomy and disease and should be reserved to cases in which standard imaging sequences are not sufficiently diagnostic.

Adolescent↗
PubMedDate not supplied

Detection of hypervascular hepatocellular carcinoma with dynamic magnetic resonance imaging with simultaneously obtained in-phase and opposed-phase echo images.

PURPOSE: The technique of double-phase echo chemical shift gradient-echo magnetic resonance (MR) imaging with the fast low-angle shot sequence (double-echo FLASH) provides in-phase and opposed-phase (double-phase) images simultaneously. The purpose of this study was to assess whether the dynamic study with a combination of in-phase and opposed-phase (double-phase) echo images improves the detectability of hypervascular hepatocellular carcinoma (HCC) compared with that with either in-phase or opposed-phase images alone. METHOD: Thirty-seven patients with 107 hypervascular HCCs who underwent the whole-liver double-phase echo dynamic MR imaging were enrolled in the study. Three radiologists blindly read in-phase images alone, opposed-phase images alone, and then double-phase images together. Sensitivity and positive predictive values as well as the areas below the alternative-free response receiver operating characteristic curve (Az values) for each imaging technique were calculated and compared statistically. RESULTS: The mean sensitivity, positive predictive values, and Az values for hypervascular HCCs were 51%, 77%, and 0.52 for in-phase imaging; 55%, 86%, and 0.58 for opposed-phase imaging; and 57%, 84%, and 0.63 for double-phase imaging, respectively. The mean sensitivity for opposed-phase imaging was significantly higher than that for in-phase imaging (P < 0.05), and the mean sensitivity for double-phase imaging was higher than that for in-phase imaging (P < 0.01). The mean Az value for the double-phase imaging was significantly higher than that for in-phase imaging (P < 0.01). CONCLUSION: Dynamic MR imaging with double-phase images was recommended for the detection of hypervascular HCC.

Adult↗
PubMed1995

Myocardial perfusion imaging with 99mTc tetrofosmin. Comparison to 201Tl imaging and coronary angiography in a phase III multicenter trial. Tetrofosmin International Trial Study Group.

BACKGROUND: Our objective was to compare the sensitivity and specificity of tetrofosmin, a new 99mTc-labeled myocardial perfusion imaging agent for the detection of myocardial perfusion abnormalities, with those of 201Tl and coronary angiography. Our hypothesis was that same-day stress/rest tetrofosmin imaging could provide data comparable to those of 201Tl imaging. Myocardial perfusion imaging plays an important role for the evaluation of coronary artery disease. Newer 99mTc-labeled agents offer several advantages over 201Tl, the conventional myocardial perfusion imaging agent. Tetrofosmin is a new 99mTc-labeled agent with promising results in preliminary studies. METHODS AND RESULTS: Two hundred fifty-two patients with suspected coronary artery disease were enrolled in 10 centers in the United States and Europe. All patients underwent exercise and rest myocardial perfusion imaging with 99mTc-tetrofosmin using two separate injections of the radiotracer 4 hours apart on the same day. Planar images were obtained in three standard views 15 to 60 minutes after radiotracer injection. Patients also underwent standard exercise and redistribution planar 201Tl imaging within 2 weeks of tetrofosmin imaging. In addition, 58 healthy subjects with low likelihood of coronary artery disease underwent exercise and rest tetrofosmin imaging. Coronary angiograms were available in 181 patients with suspected coronary artery disease. All radionuclide images were processed in the central core laboratory and interpreted blindly by a panel of four experienced readers. 201Tl images and tetrofosmin images were read separately. Discrepancies were resolved by consensus. The workload, peak heart rate, and double products were comparable during exercise for both imaging agents. Technically acceptable paired 201Tl and tetrofosmin images were available in 224 of 252 patients. Tetrofosmin images were generally of good quality, with low extracardiac activity, and easy to interpret. Patients were categorized as showing normal, ischemia, infarction, or mixture with each imaging modality. Precise concordance for each of these categories was 59.4% (kappa = 0.44; 95% CI, 0.35 to 0.53). When patients were categorized as normal or abnormal, the concordance was 80.4% (kappa = 0.55; 95% CI, 0.43 to 0.67). When each of five anatomic territories (septal, anterior, inferior, lateral, and apical) was categorized as normal versus abnormal, the concordance varied from 81% to 90%. When similar comparison was made for the specific category of abnormality, the concordance was 64% to 84%. When coronary angiography was used as the criterion, the sensitivity and positive and negative predictive accuracy of tetrofosmin and 201Tl were comparable. The normalcy rate of tetrofosmin images in the healthy subjects with low likelihood of coronary artery disease was 97%. CONCLUSIONS: 99mTc tetrofosmin is a new myocardial imaging agent with favorable imaging characteristics with results comparable to those of 201Tl.

Adult↗
PubMed2001

Diffusion-weighted MR imaging of intracerebral masses: comparison with conventional MR imaging and histologic findings.

BACKGROUND AND PURPOSE: The purposes of this study were to find the role of diffusion-weighted MR imaging in characterizing intracerebral masses and to find a correlation, if any, between the different parameters of diffusion-weighted imaging and histologic analysis of tumors. The usefulness of diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps in tumor delineation was evaluated. Contrast with white matter and ADC values for tumor components with available histology were also evaluated. METHODS: Twenty patients with clinical and routine MR imaging/CT evidence of intracerebral neoplasm were examined with routine MR imaging and echo-planar diffusion-weighted imaging. The routine MR imaging included at least the axial T2-weighted fast spin-echo and axial T1-weighted spin-echo sequences before and after contrast enhancement. The diffusion-weighted imaging included an echo-planar spin-echo sequence with three b values (0, 300, and 1200 s/mm(2)), sensitizing gradient in the z direction, and calculated ADC maps. The visual comparison of routine MR images with diffusion-weighted images for tumor delineation was performed as was the statistical analysis of quantitative diffusion-weighted imaging parameters with histologic evaluation. RESULTS: For tumors, the diffusion-weighted images and ADC maps of gliomas were less useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo images in definition of tumor boundaries. Additionally, in six cases of gliomas, neither T2-weighted spin-echo nor diffusion-weighted images were able to show a boundary between tumor and edema, which was present on contrast-enhanced T1-weighted and/or perfusion echo-planar images. The ADC values of solid gliomas, metastases, and meningioma were in the same range. In two cases of lymphomas, there was a good contrast with white matter, with strongly reduced ADC values. For infection, the highest contrast on diffusion-weighted images and lowest ADC values were observed in association with inflammatory granuloma and abscess. CONCLUSION: Contrary to the findings of previous studies, we found no clear advantage of diffusion-weighted echo-planar imaging in the evaluation of tumor extension. The contrast between gliomas, metastases, meningioma, and white matter was generally lower on diffusion-weighted images and ADC maps compared with conventional MR imaging. Unlike gliomas, the two cases of lymphomas showed hyperintense signal on diffusion-weighted images whereas the case of cerebral abscess showed the highest contrast on diffusion-weighted images with very low ADC values. Further study is required to find out whether this may be useful in the differentiation of gliomas and metastasis from lymphoma and abscess.

Adult↗
PubMed2006

MDCT of pancreatic adenocarcinoma: optimal imaging phases and multiplanar reformatted imaging.

OBJECTIVE: The objective of our study was to evaluate the individual contributions of arterial, pancreatic parenchymal, and portal venous phase (PVP) images and the utility of coronal and sagittal multiplanar reformatted (MPR) images in the assessment of pancreatic adenocarcinoma using triple-phase MDCT. MATERIALS AND METHODS: Thirty-one patients with and 35 patients without pancreatic adenocarcinoma underwent triple-phase MDCT. Three radiologists independently attempted to detect pancreatic adenocarcinoma and assess local extension using the MDCT images in five sessions. The first three sessions involved sets of images obtained in arterial phase, pancreatic parenchymal phase, and PVP separately and respectively. In the fourth session, a combination of axial images from all phases was evaluated. During the fifth session, radiologists had access to coronal and sagittal MPR images together with the axial images obtained in all phases. Results were compared with surgical findings using receiver operating characteristic (ROC) analysis and kappa statistics. RESULTS: Regarding tumor detection, the image set composed of coronal and sagittal MPR images and of axial images obtained in all phases had a significantly higher value for the area under the ROC curve (A(Z), 0.98 +/- 0.01) than the other image sets and yielded the highest sensitivity (93.5%). The sensitivity of the arterial phase image set (80.6%) was significantly lower than that of all other image sets. Whereas the image set composed of coronal and sagittal MPR images and axial images obtained in all phases yielded the highest kappa values for all local extension factors evaluated, the image set composed of only arterial phase images yielded the lowest kappa values for almost all of the factors. CONCLUSION: A combination of pancreatic parenchymal phase and PVP imaging is necessary and efficient for the assessment of pancreatic adenocarcinoma. The addition of coronal and sagittal MPR images increased the performance of MDCT, especially in the evaluation of local extension.

Adenocarcinoma↗
PubMed1994

MR imaging of peritoneal disease: comparison of contrast-enhanced fast multiplanar spoiled gradient-recalled and spin-echo imaging.

OBJECTIVE: We performed this study to compare contrast-enhanced fast multiplanar spoiled gradient-recalled (SPGR) MR imaging with unenhanced spin-echo imaging for the detection of benign and malignant peritoneal abnormalities. MATERIALS AND METHODS: We retrospectively reviewed abdominal MR images of 34 patients with proved peritoneal abnormalities, including 21 patients with malignant and 13 patients with benign peritoneal disease. Six additional patients had false-positive interpretations of their MR examinations because of diaphragmatic thickening and enhancement. Unenhanced T1-weighted images, fast spin-echo T2-weighted images, and breath-hold fast multiplanar SPGR images obtained immediately and 10-15 min after IV injection of gadopentetate dimeglumine were available. Images were reviewed for evidence of peritoneal disease by two observers who had no knowledge of the clinical findings. The four types of images were separately evaluated for peritoneal thickening, masses, and abnormal enhancement. The anatomic location, thickness, and pattern of thickening of the peritoneum were noted. Results were correlated with surgical findings or results of percutaneous biopsy. RESULTS: Immediate and delayed contrast-enhanced fast multiplanar SPGR images showed malignant peritoneal tumor in all 21 cases, compared with T1-weighted images, which showed tumor in 11 cases (p < .01), and fast spin-echo T2-weighted images, which showed tumor in 13 cases (p < .01). Enhancement of the peritoneal tumor increased the tumor's conspicuity, particularly on delayed fast multiplanar SPGR images, which were selected as the best sequence for detection of peritoneal tumor in 18 of the 21 cases. The MR findings varied widely from moderately and regularly thickened, enhancing peritoneum to very thick (> 1 cm) and lobular or masslike peritoneal thickening with enhancement. Delayed fast multiplanar SPGR images showed evidence of benign peritoneal disease in all 13 cases compared with immediate fast multiplanar SPGR images, which showed disease in 12 cases (p > .05); T1-weighted images, which showed disease in four cases (p < .05); and fast spin-echo T2-weighted images, which showed disease in only one case (p < .01). In the benign forms of peritoneal disease, the peritoneum was often regular in contour and tended to be thinner than in the cases of malignant peritoneal tumor, in which the peritoneum was generally thicker and more lobular or masslike. However, significant overlap was seen between the MR findings in benign and malignant forms of peritoneal disease. CONCLUSION: Detection of peritoneal abnormalities with MR imaging can be improved by using contrast-enhanced fast multiplanar SPGR imaging. The findings of peritoneal thickening and enhancement are best depicted on delayed images.

Adult↗
PubMed1996

Hepatic malignancies: usefulness of acquisition of multiple arterial and portal venous phase images at dynamic gadolinium-enhanced MR imaging.

PURPOSE: To determine whether liver tumor detection is increased by acquiring multiple dynamic arterial phase and portal venous phase magnetic resonance (MR) images. MATERIALS AND METHODS: Dynamic MR imaging was performed in 205 patients at 1.5 T with use of a fast spoiled gradient-echo technique (repetition time, 9-12 msec; echo time, 2.1-3.0 msec; flip angle, 30 degrees). During intravenous bolus injection of gadopentetate dimeglumine or gadoteridol (0.1 mmol/kg), nine images were acquired at each of 10-12 locations over approximately 120 seconds. The number of tumors detected on arterial phase and portal venous phase images and unenhanced T1- and T2-weighted spin-echo (SE) images was evaluated separately. Data obtained in 75 patients with proved malignancies were analyzed. RESULTS: At imaging, 220 malignant tumor nodules were depicted. At prospective review of all images, 110 hepatocellular carcinomas (HCCs) were detected: 82 (75%) on unenhanced T1-weighted SE images, 83 (75%) on unenhanced T2-weighted SE images, 92 (84%) on arterial phase images, and 76 (69%) on portal venous phase images. At prospective review, eight HCCs were detected on only arterial phase images, one on only portal venous phase images, nine on both arterial and portal venous phase images, and 11 on only unenhanced SE images. The 18 additional HCCS detected prospectively on only dynamic images increased HCC detection by 21% over prospective detection on only SE images. Detection of non-HCC tumors (including metastases) did not increase with dynamic images. CONCLUSION: Acquisition of multiple dynamic arterial phase and portal venous phase images increased detection of HCC but not metastases.

Adult↗
PubMed1997

MR imaging of the gastrointestinal tract with i.v., gadolinium and diluted barium oral contrast media compared with unenhanced MR imaging and CT.

OBJECTIVE: To determine an optimal MR imaging technique and pulse sequence for evaluating mural and serosal disease of the gastrointestinal tract, we administered 2% oral barium sulfate and obtained fat-suppressed gadolinium-enhanced breath-hold fast multiplanar spoiled gradient-recalled (FMPSPGR) MR images. We then compared these images with spin-echo T1-weighted and T2-weighted fast spin-echo MR images and with CT images. SUBJECTS AND METHODS: Thirty-one patients with suspected diseases of the gastrointestinal tract were imaged with spin-echo T1-weighted, fast spin-echo T2-weighted, and fat-saturated gadolinium-enhanced FMPSPGR MR imaging. Before undergoing MR imaging, all patients received 1350 ml of 2% barium sulfate oral contrast media. For CT scans, patients received 120 ml of iodinated i.v. contrast material and 2% barium sulfate oral contrast material. CT and MR images were retrospectively and independently reviewed by two radiologists for ability to see normal bowel wall, for the presence of abnormal gastrointestinal tract mural thickening or enhancement, and for overall gastrointestinal tract visualization. Findings were correlated with surgical findings, endoscopy, and barium studies. RESULTS: Ten patients had benign disease, 16 had malignant gastrointestinal tract disease, and five had no gastrointestinal tract abnormalities. In 94% of patients, the gadolinium- and barium-enhanced FMPSPGR MR images were superior to CT and spin-echo MR sequences for depicting the wall of the normal bowel (p < .001). For the two observers, the FMPSPGR MR images with i.v. and oral contrast material were seen as revealing 94% and 95% of bowel segments with malignant or inflammatory mural thickening or serosal tumor. In comparison, CT revealed 64% and 72% (p < .01 and p < .0001, respectively), fast spin-echo T2-weighted MR images revealed 21% and 28% (p < .0001), and T1-weighted MR images revealed 17% and 18% (p < .0001). The gadolinium- and barium-enhanced MR images were preferred for overall gastrointestinal tract visualization in 65% of patients compared with 1% for CT scans (p < .001). In 32% of patients, the enhanced MR images were equivalent to CT images. CONCLUSION: MR evaluation of the gastrointestinal tract requires bowel distention with oral contrast material as well as motion reduction techniques, including glucagon and rapid gradient-echo pulses that allow breath-hold imaging. Fat-suppressed gadolinium-enhanced FMPSPGR MR imaging with diluted barium oral contrast media is effective for imaging benign and malignant mural and serosal abnormalities of the gastrointestinal tract.

Administration, Oral↗
PubMedDate not supplied

Detection of hepatocellular carcinoma: comparison of dynamic three-phase computed tomography images and four-phase computed tomography images using multidetector row helical computed tomography.

PURPOSE: The purpose of our study was to assess the value of additional early arterial phase computed tomography (CT) imaging in the detection of hepatocellular carcinoma (HCC) by comparing three-phase and four-phase imaging by using multidetector row helical CT. METHODS: Twenty-five patients with 33 HCCs underwent four-phase helical CT imaging. The diagnosis was established by pathologic examination after surgical resection in 19 patients and by biopsy in six. Four-phase CT imaging comprises early arterial, late arterial, portal venous, and delayed phase imaging obtained 25 seconds, 45 seconds, 75 seconds, and 180 seconds after the start of contrast material injection using multidetector row helical CT. Three-phase CT images (late arterial, portal venous, and delayed phase) and four-phase CT images (early arterial, late arterial, portal venous, and delayed phase) were interpreted independently for the detection of HCC by three blinded observers on a segment-by-segment basis. Sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (Az) for three-phase CT images and four-phase CT images were calculated. The enhancement pattern of HCC was analyzed on early arterial and late arterial phase imaging. RESULTS: The mean sensitivity of three- and four-phase CT images was 94% and 93%, respectively. The differences between sensitivities were not statistically significant (all p > 0.05). The mean specificities of three- and four-phase CT images were 99% and 98%, respectively. The differences between the specificities were not statistically significantly (all p > 0.05). Neither were the mean areas under the ROC curve for four-phase CT images (Az = 0.976) and three-phase CT images (Az = 0.971) statistically significant (p > 0.05). On early arterial phase imaging, 16 HCCs were hyperattenuating and 17 HCCs were isoattenuating. On late arterial phase imaging, 24 HCCs were hyperattenuating and nine HCCs were isoattenuating. CONCLUSIONS: Additional early arterial phase imaging did not improve the detection of HCC compared with three-phase CT images, including late arterial, portal venous, and delayed phase imaging.

Adult↗
PubMed2006

Patellar tendons with normal imaging and pain: change in imaging and pain status over a volleyball season.

OBJECTIVE: Patellar tendon injury commonly presents as abnormal imaging with pain or abnormal imaging without pain. Normal imaging with pain has also been reported clinically, but little is known about the behavior of these tendons over time. This study investigated the behavior of tendons with normal imaging and pain over a volleyball season. DESIGN: Prospective study. SETTING: Institutional. PARTICIPANTS: One hundred and one male and female volleyball players. MAIN OUTCOME MEASUREMENTS: At the beginning and end of the season ultrasound determined imaging status and the single leg decline squat test determined pain. The imaging and pain status at follow-up of tendons with normal imaging and pain at baseline was reported and contrasted to the imaging and pain status of the other patellar tendon injuries. RESULTS: Tendons with normal imaging and pain [relative risk (RR) 15.1], abnormal imaging without pain (RR 14.6), and abnormal imaging with pain (RR 51.5) had a greater risk of having abnormal imaging with pain at the end of the season when compared with normal tendons (P < 0.01). Among tendons with normal imaging and pain at baseline, 27% had abnormal imaging without pain and 21% contained abnormal imaging with pain at the end of the season. CONCLUSIONS: Patellar tendons with normal imaging and pain at the beginning of a volleyball season are equally as likely to have abnormal imaging and pain at the end of the season as tendons with abnormal imaging without pain. Normal imaging with pain may represent a clinically relevant patellar tendon injury.

Adolescent↗
PubMed2000

Grading, image analysis, and stereopsis of digitally compressed fundus images.

PURPOSE: To investigate the effects of image digitization and compression on the ability to identify and quantify features in color fundus photographs. METHODS: Color fundus photographs were digitized as tagged image file format (TIFF) and high-compression (80:1) and low-compression (30:1) joint photographic experts group (JPEG) images. Rerendered images were subjected to standard grading protocols developed for a clinical trial, and digitized images were subjected to image analysis software for drusen identification and quantitation. Re-created stereoscopic images were compared subjectively with originals. RESULTS: Original, TIFF, and low-compression (30:1) JPEG images were virtually indistinguishable when subjected to close scrutiny with magnification. The overall quality of high-compression (80:1) JPEG images and images digitized at 500 dots per inch was markedly reduced. Protocol grading of original and digitized images was highly concordant within the repeatability of multiple grading of original images. The area subtended by drusen differed by less than 1.0% for all uncompressed and compressed image pairs quantified. Stereoscopic information was accurately preserved when compared with originals for TIFF and low-compression JPEG images. CONCLUSIONS: Fundus images can be digitized and stored with significant compression while preserving stereopsis and image quality suitable for quantitative image analysis and semiquantitative grading. Low-compression (30:1) JPEG images may be suitable for archiving and telemedical applications.

Depth Perception↗
PubMed2004

Three-dimensional dynamic liver MR imaging using sensitivity encoding for detection of hepatocellular carcinomas: comparison with superparamagnetic iron oxide-enhanced mr imaging.

PURPOSE: To assess the diagnostic performance of three-dimensional dynamic liver imaging with sensitivity encoding (SENSE), including double arterial phase images and increased resolution, by comparing it to superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging for the detection of hypervascular hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Twenty-seven consecutive patients with 50 HCCs underwent Gd-BOPTA-enhanced dynamic imaging using SENSE and SPIO-enhanced MR imaging with at least a 24-hour interval between examinations. Using a three-dimensional gradient-echo technique applying SENSE, dynamic imaging consisting of double arterial phase-, portal phase- and delayed phase-images, was obtained. Using T2-weighted turbo spin-echo and T2*-weighted fast imaging with steady-state precession sequence, SPIO-enhanced MR imaging was obtained. For qualitative analysis, the diagnostic accuracy of both MR examinations for detecting the 50 HCCs was evaluated using the alternative free-response receiver operating characteristic method. Sensitivity and positive predictive value were also evaluated. RESULTS: The mean sensitivity and positive predictive value of three-dimensional dynamic imaging with SENSE were 91.3% and 89.2%, respectively, and those of SPIO-enhanced imaging were 77.3% and 92.6 %, respectively. There was a significant difference in sensitivity between the two images (P <0.05). The mean Az value of three-dimensional dynamic imaging with SENSE (0.97 +/- 0.01) was significantly higher than that of SPIO-enhanced imaging (0.90 +/- 0.02) (P=0.00). CONCLUSION: Three-dimensional dynamic liver MR imaging using SENSE for acquiring double arterial phase images is more efficient than SPIO-enhanced MR imaging for detecting HCCs.

Carcinoma, Hepatocellular↗