Comparison of breath-hold multishot echo-planar and respiratory triggered fast-spin-echo sequences for T2-weighted MRI of liver lesions

The purpose of this study was to evaluate the usefulness of multishot echo-planar imaging in detecting liver tumors in comparison with respiratory triggered T2-weighted fast-spin-echo (FSE) imaging. Thirty-two patients with 70 focal liver lesions were imaged using a 1.5-T high speed MR imager. Eight-shot echo-planar images covering the whole liver were acquired during a single breath-hold period. FSE images were acquired with respiratory triggering in approximately 4 minutes. Lesion detectability and image quality of the two pulse sequences were analyzed qualitatively. Quantitative analysis was performed by means of signal-to-noise and tumor-liver contrast-to-noise analysis. Lesion detectability was comparable in both solid (86.3% vs 90.2%: .3 < P < .5) and nonsolid lesions (89.5% vs 100%: .3 < P < .5) between echo-planar and FSE images. Echo-planar imaging provided significantly reduced image artifact, better lesion conspicuity, and anatomic detail compared with FSE imaging. The signal-to-noise and contrast-to-noise ratios of echo-planar images were significantly higher than those of FSE images. Breath-hold eight-shot echo-planar imaging can be an alternative to T2-weighted FSE imaging because it can provide comparable image quality in a substantially decreased acquisition time.     

Black-blood T2* technique for myocardial iron measurement in thalassemia

PURPOSE: To compare the effectiveness and reproducibility of a new black-blood sequence vs. a conventional bright-blood gradient-echo T2* sequence for myocardial iron overload measurement in thalassemia. MATERIALS AND METHODS: Twenty thalassemia patients were studied. Black-blood sequence images were acquired in diastole after a double inversion recovery (DIR) preparation pulse. Bright-blood sequence images were acquired in both early systole and late diastole. The data were randomized and the T2* analysis was performed blindly by two independent observers. RESULTS: The T2* values from the black-blood sequence were comparable to those of the conventional bright-blood sequence (25.7 +/- 12.9 msec vs. 26.4 +/- 14.2 msec in early systole, P = 0.44; and 25.2 +/- 13.1 msec in late diastole, P = 0.41). The coefficient of variation (CV) for black-blood image T2* analysis was 4.1% compared with 8.9% (early systole P = 0.03) and 7.8% (late diastole P = 0.05) for bright-blood image analysis. CONCLUSION: The black-blood T2* technique yields high-contrast myocardial images, provides clearly depicted myocardial borders, and avoids blood signal contamination of the myocardium while yielding improvements in interobserver variability.     

Flat-panel display (LCD) versus high-resolution gray-scale display (CRT) for chest radiography: an observer preference study

OBJECTIVE: Our objective was to compare cathode ray tube (CRT) display with liquid crystal display (LCD) for soft-copy viewing of chest radiographs in a clinical setting. MATERIALS AND METHODS: We displayed 80 posteroanterior digital chest radiographs side by side on a 5-megapixel CRT display and a 3-megapixel LCD. Gradation characteristics of both monitors were adjusted to DICOM display standards. Using a 4-point scale, seven radiologists ranked overall image quality and visibility of anatomic landmarks. Data analysis included Wilcoxon's rank sum test to assess the significance of preference for the different display modes and calculation of the percentage of images ranked equally by at least five of the seven radiologists. RESULTS: Wilcoxon's rank sum test found significant preferences (p < 0.001) for the CRT display for visualization of structures in low-attenuation areas of the thorax and for the LCD for visualization of structures in high-attenuation areas of the thorax. Overall image quality was ranked equal by at least five radiologists in 70% of cases, whereas for the remaining images a significant preference was found for the CRT display. CONCLUSION: We conclude that, under subdued ambient lighting conditions and without use of windowing, for most images the overall quality is equal with high-resolution CRT display and LCD. In images judged preferentially, we found a significant superiority for LCD for delineating mediastinal structures and for CRT display for delineating structures in the lung.     

Dynamic antral scintigraphy following solid and liquid meals in healthy human subjects

AIMS: Dynamic antral scintigraphy (DAS), a non-invasive technique for the assessment of post-prandial gastric contractions, has been used to demonstrate abnormal contractility in several clinical conditions. The objective of the present study was to assess differences between solid and liquid meals regarding gastric contractions in healthy volunteers using DAS. METHODS: Ten healthy male volunteers were studied after ingesting solid or liquid meals [approximately 1670 kJ (approximately 400 kcal)] labelled with 99mTc phytate and administered in a random order. Gastric images were acquired for 120 min for gastric emptying half-time (T1/2) measurement. Dynamic (1 frame x s(-1)) images of the gastric antrum were acquired at 30 min intervals for 4 min for the assessment of antral contractility. RESULTS: Gastric emptying T1/2 values for solid and liquid meals were similar (58.1+/-19.06 min vs. 69.4+/-6.76 min; P=0.13). For the solid meal, average values for both frequency (3.08+/-0.15 cycles x min(-1) vs. 2.78+/-0.18 cycles x min(-1); P=0.003) and amplitude (33.94+/-5.2% variation vs. 24.09+/-7.37% variation; P=0.002) of antral contractions were significantly higher than those obtained with the liquid meal. For either of the test meals, none of the antral contractility variables correlated with gastric emptying T1/2. CONCLUSIONS: Dynamic antral scintigraphy is capable of detecting differences between solid and liquid meals concerning post-prandial gastric antral contractions under physiological conditions. The frequency and amplitude of gastric antral contractions after a solid meal are greater than after an exclusively liquid meal of similar calorie content, in spite of lack of a difference regarding gastric emptying.     

Multispectral magnetic resonance image analysis using principal component and linear discriminant analysis

PURPOSE: To explore the possibilities of combining multispectral magnetic resonance (MR) images of different patients within one data matrix. MATERIALS AND METHODS: Principal component and linear discriminant analysis was applied to multispectral MR images of 12 patients with different brain tumors. Each multispectral image consisted of T1-weighted, T2-weighted, proton-density-weighted, and gadolinium-enhanced T1-weighted MR images, and a calculated relative regional cerebral blood volume map. RESULTS: Similar multispectral image regions were clustered, while dissimilar multispectral image regions were scattered in a single plot. Both principal component and linear discriminant analysis allowed discrimination between healthy and tumor regions on the image. In addition, linear discriminant analysis allowed discrimination between oligodendrogliomas and astrocytomas. However, the discriminant analysis method was partially capable of recognizing the tumor identity in unknown multispectral images. CONCLUSION: The proposed method may help the radiologist in comparing multispectral MR images of different patients in a more easy and objective way.     

Dose reduction in digital chest radiography and perceived image quality

The aim of the study was to investigate whether radiologists can rank the image quality of digital radiographs with different doses; a preliminary study investigated whether reduced dose images provide sufficient diagnostic quality. Raw data of 40 chest radiographs (posteroanterior (PA) and lateral) obtained with a full-field slot-scan charge-coupled device system in 20 patients with chest pathology were used. Noise was added to simulate reduced dose levels to 50%, 25% and 12%. Four observers ranked the quality of the corresponding images and judged the diagnostic quality. Linear regression analysis was performed. Differences were found in image quality at the different dose levels for both PA (p相似文献   

Automatic image quality quantification and mapping with an edge-preserving mask-filtering algorithm

Background: Imaging modalities in digital radiology produce large amounts of data for which image quality should be determined in order to validate the diagnostic operation.

Purpose: To develop an automatic method for image quality assessment.

Material and Methods: A filtering algorithm using a moving square mask was applied to create a map of filtered local intensity and noise values. Image quality scores were calculated from the filtered image data. The procedure was applied to technical and anthropomorphic (radiosurgery verification phantom [RSVP] head) phantom images obtained with varying radiation dose, field of view (FOV), and image content. The method was also applied to a clinical computed tomography (CT) brain image.

Results: The image quality score (IQs) of the phantom images increased from 0.51 to 0.82 as the radiation dose (CTDI_vol) increased from 9.2 to 74.3 mGy. Correlation of the IQs with the pixel noise was R² = 0.99. The deviation (1 SD) of IQs was 2.8% when the reconstruction FOV was set between 21 and 25 cm. The correlation of IQs with the pixel noise was R² = 0.98 with variable image contents and dose. Automatic tube current modulation applied to the RSVP phantom scan reduced the variation in the calculated image quality score by about 60% compared to the use of a fixed tube current.

Conclusion: The image quality score provides an efficient tool for automatic quantification of image quality. The presented method also produces a 2D image quality map, which can be used for further image analysis.     

Value of image fusion using single photon emission computed tomography with integrated low dose computed tomography in comparison with a retrospective voxel-based method in neuroendocrine tumours

The objective was the evaluation of single photon emission computed tomography (SPECT) with integrated low dose computed tomography (CT) in comparison with a retrospective fusion of SPECT and high-resolution CT and a side-by-side analysis for lesion localisation in patients with neuroendocrine tumours. Twenty-seven patients were examined by multidetector CT. Additionally, as part of somatostatin receptor scintigraphy (SRS), an integrated SPECT–CT was performed. SPECT and CT data were fused using software with a registration algorithm based on normalised mutual information. The reliability of the topographic assignment of lesions in SPECT–CT, retrospective fusion and side-by-side analysis was evaluated by two blinded readers. Two patients were not enrolled in the final analysis because of misregistrations in the retrospective fusion. Eighty-seven foci were included in the analysis. For the anatomical assignment of foci, SPECT–CT and retrospective fusion revealed overall accuracies of 91 and 94% (side-by-side analysis 86%). The correct identification of foci as lymph node manifestations (n=25) was more accurate by retrospective fusion (88%) than from SPECT–CT images (76%) or by side-by-side analysis (60%). Both modalities of image fusion appear to be well suited for the localisation of SRS foci and are superior to side-by-side analysis of non-fused images especially concerning lymph node manifestations.     

Variation of the coronary calcium score depending on image reconstruction interval and scoring algorithm

RATIONALE AND OBJECTIVES: To evaluate the reconstruction interval dependent bandwidth of the coronary calcium score, considering different methods of image reconstruction and quantification of coronary calcifications. MATERIALS AND METHODS: Seventy-five patients underwent coronary calcium scoring by use of retrospectively ECG-gated multislice spiral CT. In all patients overlapping and nonoverlapping image reconstruction was performed every 10% of the RR-interval. Coronary calcium score was calculated for every reconstructed image series using the Agatston score and a volumetric scoring method. In 25 patients the analysis was performed twice to determine the reconstruction interval dependent intraobserver variability. RESULTS: For nonoverlapping image reconstruction the median of the calcium score determined by the Agatston method ranged from 125.8 to 216.2 and from 166.9 to 211.7 for the volumetric scoring method. For overlapping image reconstruction the corresponding values ranged from 91.6 to 160.5 for the Agatston score and 128.3 to 175.3 for the volumetric calcium score. Reconstruction interval dependent median (mean) variation of the coronary calcium score ranged from 24.1 (45.5)% for nonoverlapping image reconstruction using the Agatston score to 17.5 (25.2)% utilizing a volumetric calcium score with overlapping image reconstruction. There was no statistical significant (P< 0.05) difference between the different methods. Intraobserver variability for the different image reconstruction intervals ranged from 0.78% to 21.51%. The least intraobserver variability was found for overlapping image reconstruction during the diastole using the volumetric scoring method. CONCLUSIONS: Diastolic image reconstruction at 50% or 60% of the RR-interval is recommendable for retrospectively ECG-gated multislice spiral CT. Volumetric calcium scoring and overlapping image reconstruction are beneficial to reduce the variation of the coronary calcium score.     

Differentiating benign from malignant solid breast masses: comparison of two-dimensional and three-dimensional US

PURPOSE: To compare prospectively obtained static two-dimensional (2D) and three-dimensional (3D) ultrasonographic (US) images in the diagnostic performance of radiologists with respect to the differentiation of benign from malignant solid breast masses with histopathologic examination as the reference standard. MATERIALS AND METHODS: This study had institutional review board approval, and patient informed consent was obtained. Conventional 2D and 3D US images were obtained from 141 patients (age range, 25-71 years; mean age, 46 years) with 150 solid breast masses (60 cancers and 90 benign lesions) before excisonal or needle biopsy. Four radiologists who had not performed the examinations independently reviewed 2D US images and stored 3D US data and provided a level of suspicion concerning probability of malignancy. The sensitivity, specificity, and negative predictive values of 2D images were compared with those of 3D US images. RESULTS: For all readers, 3D US images were the same as or better than 2D US images in terms of sensitivity (100% vs 100% for reader 1; 100% vs 98% for reader 2; 98% vs 93% for reader 3; 93% vs 92% for reader 4), specificity (58% vs 56% for reader 1; 51% vs 46% for reader 2; 83% vs 72% for reader 3; 86% vs 84% for reader 4), and negative predictive values (100% vs 100% for reader 1; 100% vs 98% for reader 2; 99% vs 94% for reader 3; 95% vs 94% for reader 4). These differences, however, were not statistically significant (P > .05). CONCLUSION: The performance of the radiologists with respect to the characterization of solid breast masses with static 2D US images was similar to that with 3D US data.     

MR imaging with spatially variable resolution.

In some situations it may be advantageous to produce "locally focused" magnetic resonance images that have nonuniform spatial resolution matching the expected local rate of spatial variation in the object. Because such an image has fewer pixels than a conventional image with uniformly high resolution, it can be reconstructed from fewer signals, acquired in less time. This can be done by using a highly convergent representation of the image as a sum of orthonormal functions with slow (fast) spatial variation in relatively homogeneous (heterogeneous) parts of the object. Since this series is shorter than a conventional truncated Fourier series, its terms can be calculated from a subset of the usual array of phase-encoded signals. The optimal choice of these phase encodings, which are usually scattered nonuniformly in k space, results in minimization of noise in the reconstructed image. The technique is illustrated by applying it to simulated data and to data from images of phantoms.     

Value of image fusion in the staging of prostatic carcinoma

PURPOSE: We assessed the value of image fusion in the staging of prostatic cancer in a series of 32 patients who underwent preoperative evaluation with transrectal colour-Doppler ultrasonography (TRUS) and magnetic resonance imaging (MRI). MATERIALS AND METHODS: Colour-Doppler TRUS exams were performed using a 7.5-MHz biplanar probe. MRI exams were done with a scanner operating at 1.5 Tesla (T) using an endorectal coil. All patients underwent radical prostatectomy within 2 weeks from the imaging assessment. Whole-mount sections were prepared from the surgical specimens and were subsequently digitised by using a high-resolution scanner. The Digital Imaging and Communications in Medicine (DICOM) TRUS and MR images as well as the digitised pathological images were transferred to a graphic workstation to perform image fusion. RESULTS: Image fusion was technically possible in 25/32 cases in which axial TRUS images were available. The following fusion images were obtained: TRUS + pathological sections; MRI + pathological sections; TRUS + MRI + pathological sections. The final pathological staging concerning the T status was: four pT2b, fourteen pT2c, three pT3a and four pT3b. The three types of image fusion led to the following results: TRUS + pathological sections, correct staging in 20/25 cases (accuracy 80%); MRI + pathological sections, correct staging in 22/25 cases (accuracy 88%); TRUS + MRI + pathological sections, correct staging in 23/25 cases (accuracy 92%). CONCLUSIONS: Our study suggests that by using image fusion between colour-Doppler TRUS and endorectal MRI, it is possible to improve the accuracy of pathological staging in patients who are candidates for radical prostatectomy.     

Effect of the reconstruction window obtained at the isovolumic relaxation period on the image quality in electrocardiographic-gated 16-multidetector-row computed tomography coronary angiography studies

OBJECTIVE: To evaluate whether images obtained during the reconstruction window responding to the isovolumic relaxation period could be used for rapid and easy postprocessing. METHODS: One hundred ten consecutive patients with suspected coronary artery disease who had previously had a multidetector computed tomography (MDCT) scan for imaging coronary arteries were enrolled in this study. The age of the patients was 59 +/- 13 years (range: 33-78 years), and 77 (70%) were male. Multidetector computed tomography was performed on a 16-detector-row computed tomography scanner during 1 breath hold (16-24 seconds). Seven different sets of images reconstructed at every 10% of the R-R interval from 30% to 90% for contrast-enhanced scans at levels containing the first several centimeters of the left and right coronary arteries were analyzed. The best of these reconstruction windows were then compared with the images reconstructed at the isovolumic relaxation period, which is the last portion of the T wave at the end of the systole, where there is not any change in ventricular volume, which causes stepladder artifacts. The step artifact was classified as excellent, good, or poor. Image quality was assessed by 2 radiologists who were not aware of each other's interpretation. RESULTS: According to the routinely used reconstructions, there were 76 patients with excellent image quality, 28 with good image quality, and 6 with poor image quality. For the period of isovolumic relaxation, there were 74 patients with excellent image quality, 25 with good image quality, and 11 with poor image quality. CONCLUSION: If one begins image analysis with the isovolumic relaxation period reconstruction window, spending less time for postprocessing analyses, good image quality can be obtained such as with other good reconstruction windows.     

Evaluating medical students on radiology clerkships in a filmless environment: use of an electronic test prepared from PACS and digital teaching collection images

RATIONALE AND OBJECTIVES: The competency of medical students in radiology clerkships is traditionally evaluated with film images, projected slides of photographed films, or printed reproductions of films. As radiology departments switch to filmless imaging, it seemed appropriate to determine the feasibility of an electronic evaluation prepared directly from digital images. MATERIALS AND METHODS: The image-based portion of a multiple-choice final examination was prepared as a PowerPoint presentation that included images downloaded from the departmental picture archiving and communication system (PACS) or digital teaching collections. The images were downloaded as bitmap files, imported to Adobe Photoshop for image editing, converted to tagged image file format, and finally imported to PowerPoint, where they were combined with text to create 50 questions. A liquid crystal diode projector displayed the questions, with a timer set to advance them automatically. RESULTS: The examination was easy and inexpensive to prepare (no photography costs). In an initial survey of 25 students, 17 (71%) of 24 students rated the resolution of images as excellent and five (21%) as good. No student gave an image a poor rating. Students preferred that images cover at least 40%-50% of the slides, and most approved of a blue background. An original allowance of 30 seconds per slide was reported to be too fast; the interval was increased to 45 seconds. CONCLUSION: An electronic final examination for medical students, prepared with images downloaded from PACS or digital teaching collections, is feasible, easy to prepare, and cost-effective, and it provides an excellent display of test images.     

Head-to-head comparison of uncorrected and scatter corrected, summed and end diastolic myocardial perfusion SPECT in coronary artery disease

OBJECTIVES: Compared with other non-invasive methods for diagnosing coronary artery disease (CAD), myocardial perfusion imaging (MPI) suffers from some lack of specificity, especially in patients with a small heart. Allowing the assessment of perfusion on end diastolic images instead of summed images, gated single photon emission computed tomography (SPECT) constitutes an attractive method for increasing the accuracy of MPI. Scatter correction, known to improve image contrast, might also be interesting. The present study aimed at comparing scatter corrected to uncorrected gated MPI for CAD diagnosis. METHODS: The results for 100 patients referred for gated 99mTc sestamibi SPECT were analysed. They were divided into two subgroups according to their end systolic volume (ESV) measured by QGS analysis (group A, ESV > or =30 ml, n=65; group B, ESV <30 ml, n=35). For each patient, a total defect score (TDS) was quantified on four polar maps (uncorrected and scatter corrected, summed, and uncorrected and scatter corrected, end diastolic). The optimal TDS separating non-CAD from CAD patients was calculated by analysis of the receiver operating characteristic (ROC) curve for the four data sets, using the coronary angiogram as a 'gold standard'. RESULTS: In the whole patient population, the accuracy of the uncorrected data was 67% for the end diastolic images and 71% for the summed images (sensitivity, 66% and 70%; specificity, 71% and 79%, respectively). After scatter correction, the accuracy did not change for the end diastolic data (accuracy, 67%; sensitivity, 63%; specificity, 93%) and increased to 74% for the summed data (sensitivity, 73%; specificity, 79%). In group A, the uncorrected data were 72% accurate for the end diastolic images and 78% for the summed images (sensitivity, 72% and 79%; specificity, 75% and 75%, respectively). After correction, the accuracy of end diastolic images increased to 77% (sensitivity, 77%; specificity, 75%), and did not change for the summed images (accuracy, 78%; sensitivity, 79%; specificity, 75%). In group B, the accuracy of uncorrected images amounted to 51% for both end diastolic and summed data (sensitivity, 48% and 40%; specificity, 60% and 80%, respectively). After correction, it increased to 57% for the end diastolic images and to 63% for the summed images (sensitivity, 48% and 64%; specificity, 80% and 60%, respectively). CONCLUSIONS: Despite lower blurring on end diastolic compared with summed images, non-scatter corrected end diastolic data were least accurate for the diagnosis of coronary artery disease in patients with a high prevalence of disease. Scatter correction, by improving the delineation of perfusion defects, increased the accuracy of quantitative MPI for the diagnosis of CAD in a large number of patients, more particularly in those with a small heart.     

Ultrasonic tissue characterization using pattern analysis of backscattered signal. The first report--outline of the system]

Ultrasonic B-mode examination is widely used. However it is unsuitable for quantitative evaluation because of modification during the image processing procedure. The authors constructed amplitude images and mean frequency images using ultrasonic backscattered signals directly and judged the image patterns quantitatively by texture analysis. As the probabilistic distribution of amplitude is solved mathematically, we could evaluate amplitude images quantitatively, unlike B-mode images. We also used mean frequency images which display frequency information to compensate for B-mode image (also directly constructed amplitude images) constructed with only amplitude information. This work describes the outline of the system and results of some clinical applications. As application, the data were collected from testes of healthy young males and azoospermic patients. On B-mode images, no difference between these groups could be found. But there were differences on image appearance of amplitude and mean frequency images between them, and the difference was proved quantitatively using texture analysis. It is suggested that this system provides useful information about the differential diagnosis of diffuse disease of the organs showing so-called solid pattern.     

Acceleration of hepatobiliary excretion by lemon juice on 99mTc-tetrofosmin cardiac SPECT

BACKGROUND: We sought to determine whether drinking lemon juice reduces extra-cardiac activity and improves image quality on (99m)Tc-tetrafosmin myocardial single photon emission computed tomography (SPECT). METHODS: Eighty male patients were enrolled in this study and divided into four groups with 20 patients in each group. Each patient received 259-333 MBq tetrofosmin. Ten minutes after injection no action was taken for group 1 (G1), patients in group 2 (G2) each drank 250 ml of water, patients in group 3 (G3) each drank 250 ml of whole milk, and patients in group 4 (G4) each drank 250 ml diluted lemon juice. Myocardial perfusion imaging without attenuation correction was performed after a 1 day rest-stress protocol. Both rest and stress images were aligned at corresponding slices for comparison. Interfering activity was determined visually on reconstructed images, and the heart-to-liver (H/L) ratios were calculated with planar images at 25-30 min and at 45-50 min. RESULTS: Interfering activity was seen in 80% of G1, 70% of G2, 60% of G3, and 35% of G4 (G4 vs. G1, P=0.006) on rest images, and in 70% of G1, 60% of G2, 55% of G3, and 30% of G4 (G4 vs. G1, P=0.014) on stress images at 25-30 min. It was also observed in 60% of G1, 50% of G2, 45% of G3, and 15% of G4 (G4 vs. G1, P=0.006) on rest images, and in 50% of G1, 45% of G2, 40% of G3, and 10% of G4 (G4 vs. G1, P=0.011) on stress images at 45-50 min. The mean H/L ratios of rest images were 0.47+/-0.13 for G1, 0.71+/-0.17 for G2, 0.65+/-0.12 for G3, and 0.93+/-0.23 for G4 at 25-30 min, and 0.63+/-0.14 for G1, 0.73+/-0.14 for G2, 0.85+/-0.25 for G3, and 1.15+/-0.25 for G4 at 45-50 min. On stress images, they were 0.49+/-0.11 for G1, 0.74+/-0.16 for G2, 0.69+/-0.11 for G3, and 0.98+/-0.22 for G4 at 25-30 min, and 0.66+/-0.15 for G1, 0.77+/-0.11 for G2, 0.89+/-0.26 for G3, and 1.21+/-0.19 for G4 at 45-50 min. CONCLUSION: Drinking 250 ml of diluted lemon juice accelerates the transit of tetrofosmin through the liver parenchyma and improves image quality on (99m)Tc-tetrafosmin myocardial SPECT.     

Bezier surface reformation: an original visualization technique of cervical nerve roots on myelographic CT

Purpose The aim of this study was to assess the feasibility of an original reformation method of cervical myelographic computed tomography (CT) using the Bezier surface technique. Material and methods Presurgical myelographic computed tomography (CT) scans using a multidetector row CT scanner were performed in 25 patients with avulsion injury of the cervical nerve roots. Each volumetric data set was reformatted using Bezier surface technique to depict the individual nerve root in a single image. In the reformatted images, visualization of the dorsal and ventral nerve roots between C4 and T1 on the uninjured side (300 nerves) was rated. Results Bezier surface reformation (BSR) images depicted the dorsal and the ventral nerve roots between C4 and C8 in 125 (100%) and 125 (100%) of 125 nerves, respectively. The dorsal and the ventral nerve roots of T1 were depicted in 25 (100%) and 22 (88%) in 25 nerves, respectively. Conclusion The BSR technique of cervical myelographic CT enables simultaneous display of multiple cervical nerve roots in one image. BSR is a feasible technique for the assessment of the cervical nerve roots. Part of this article has been accepted for presentation at the Japan Radiological Conference, 2006.     

Ventilation imaging of the lung: Comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy

RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation.     

Automated determination of the right ventricular ejection fraction by digital processing of 81mKr scintigrams

A method is presented for the automated determination of the right ventricular ejection fraction (RVEF) by digital image processing of scintigrams obtained by intravenous infusion of Krypton 81m (81mKr) dissolved in a glucose solution. End-diastolic and end-systolic sum pictures were computed by the addition of approximately 30-40 frames selected from the time-activity curve of a preliminary, manually drawn, right ventricular region of interest. After processing these two images with an adaptive Wiener filter, the right ventricular contour was determined by a recently developed algorithm using morphological and functional criteria. The RVEF was calculated for a series of 51 patients from the counts in the detected right ventricular regions in the end-diastolic and end-systolic sum images. In 16 patients without evidence of cardiopulmonary disease, the mean RVEF was 50 +/- 6.1%. RVEF was significantly reduced in 18 patients with obstructive pulmonary disease (42 +/- 6.5%) and in 17 patients with congestive cardiomyopathy (36 +/- 7.1%). The correlation coefficient between two determinations of the RVEF was r = 0.94. Through digital image processing, the determination of the RVEF by radioventriculography with 81m Kr showed high reliability and reproducibility.