Look-up table (LUT) algorithms have been widely used in digital signal processing, but the article on the application of LUT algorithms in digital subtraction angiography was rarely reported. In this article, the effect of different LUT algorithms on digital subtraction angiography images is introduced. The result reveals that different LUT algorithms can bring about different effects of image. Based on analysis and comparison, we deem it possible to acquire improved images of DSA by use of some LUT algorithms with image processing.
Algorithms ; Angiography, Digital Subtraction ; methods ; Humans ; Radiographic Image Enhancement ; methods ; Radiographic Image Interpretation, Computer-Assisted ; methods

OBJECTIVETo assess image processing techniques including multiplanar reconstruction (MPR), volume rendering technique (VRT) and spiral CT angiography (SCTA) in the staging of central lung cancer (CLC), with transverse image, pathology and findings on the operation table as comparison.

METHODSForty-six suspected CLC received spiral CT examination, on basis of prospective randomization, by a Picker 6 000 scanner. Contrast medium was injected at a rate of 4 ml/s with a power injector. The study volume done in a single breath-hold was from the aortic arch to the inferior pulmonary veins, using 3-mm collimation, pitch of 1.0 and reconstruction at 1-mm interval. Six patients were excluded after operation. Transverse CT scans, MPR and VR images were studied in a double-blind way by 3 experienced radiologists, with the findings compared with the surgical and pathological results.

RESULTSPost-processing image was more accurate than transverse CT scan in T categories (95.7% vs 82.6%), chi(2) = 4.039, P = 0.044. Four cases of N3 category on transverse CT scans were not proved by surgical or pathological results. The sensitivity, specificity and accuracy rates in N categories were 75.0% (12/16), 26.9% (7/26) and 45.2% (19/42). The accuracy rate of staging was 58.7% (27/46) by transverse CT scans and 67.4% (31/46) by post-processing images (chi(2) = 0.746, P = 0.338).

CONCLUSIONPost-processing image is more accurate than transverse image in T categorizing.

Adult ; Aged ; Female ; Humans ; Image Processing, Computer-Assisted ; Lung Neoplasms ; diagnostic imaging ; Male ; Middle Aged ; Neoplasm Staging ; Radiographic Image Enhancement ; Tomography, Spiral Computed ; Tomography, X-Ray Computed

Colon cancer is one of the leading causes of cancer-related deaths, while the virtual colonoscopy plays an important role in the early detection of colon cancer. Effective colon segmentation is the basis of virtual colonoscopy. Oral contrast agent can reduce the use of laxatives, but it can to bring some difficulties in the colon segmentation. Because of the partial volume effect, the CT value of air-tagging boundary span a wide range, which are not easily eliminated. We present an effective method of colon segmentation in this paper. Firstly, we used adaptive threshold method to extract air area. Then we segmented tagging region and removed air-tagging boundary by segment region growing method based on statistical information and morphological operation. The experiments showed that the agreement between the results by manual and by orithm segmentation reached 93.4%.
Algorithms ; Colon ; diagnostic imaging ; Colonography, Computed Tomographic ; methods ; Humans ; Pattern Recognition, Automated ; methods ; Radiographic Image Enhancement ; methods ; Radiographic Image Interpretation, Computer-Assisted ; methods

Scatter radiation considerably affects radiographic image quality by reducing image contrast and contributing to a non-uniform background. Images containing a large portion of scatter radiation may result in an incorrect diagnosis. In the past few years, many efforts have been made to reduce the effects of scatter radiation on radiographic images. The purpose of this study is to accurately measure scatter fractions and evaluate the effectiveness of beam-stop arrays. To measure scatter fraction accurately, a beam-stop array and the SFC (Scatter Fraction Calculator) program were developed. Images were obtained using the beam-stop array for both an anti-scatter technique with an anti-scatter grid and an air gap technique. The scatter fractions of the images were measured using the SFC program. Scatter fractions obtained with an anti-scatter grid were evaluated and compared to scatter fractions obtained without an anti-scatter grid. Scatter fractions were also quantitatively measured and evaluated with an air gap technique. The effectiveness of the beam-stop array was demonstrated by quantifying scatter fractions under various conditions. The results showed that a beam-stop array and the SFC program can be used to accurately measure scatter fractions in radiographic images and can be applied for both developing scatter correction methods as well as systems.
Radiographic Image Enhancement

PURPOSE: To compare cephalometric measurement between measuring methods in digital and conventional lateral cephalometric radiograph. MATERIALS AND METHODS: Twenty digital and conventional lateral cephalometric radiographs were selected. In digital group, cephalometric measurements were performed manually using hardcopies and automatically using VCeph(TM) program on the monitor. In conventional group, the same measurements were performed manually on conventional films, and for automatic measurement conventional films were digitized by scanner. All measurements were performed twice by 4 observers, and 24 cephalometric variables were calculated and the time spent for each measurement was recorded. The differences in measurements data and the time spent for each measurement were compared within each group. Intra-observer and inter-observer comparisons were performed. RESULTS: In both groups, no statistically significant difference between manual and automatic measurements was observed and most of the variables didn't show statistically significant differences between methods. The observer with less experience tended to show statistically significant differences of measurements between methods, and differences from other observers. The differences of measurements between methods in digital group were lesser than those of conventional group with statistical significance in 8 variables out of 24. With automatic method and in digital group, the spent time was shorter. CONCLUSION: With direct digital radiograph, automatic method using manually idenitified landmarks can be preferable in cephalometric analysis.
Cephalometry ; Radiographic Image Enhancement

The purpose of this study was to evaluate the reproducibility of lateral cephalometric landmarks according to radiographic image enhancement, and to contribute to the identification of cephalometric landmarks. Lateral cephalograms of ten individuals were taken and stored into computer. The images were then enhanced up to four grades by Quick Ceph Image ProTM on condition that the gray-scale equalization number was 50 and the detail enhancement number was 50. After thirty two landmarks were identified on monitor images by five observers, the deviations from the mean, the distances estimated between identified points and the mean point of five identified points, were evaluated for each landmark at each enhancement grade. Through the statistical analysis, following results were obtained. 1.In case of unenhanced radiographic images, the inter-observer reproducibility of the landmarks showed a large variation. 2.The comparison of deviation from the mean according to the degree of radiographic image enhancement for each landmark showed that the inter-observer reproducibility was significantly different at 5 landmarks. 3.The landmark of pterygomaxillary fissure showed higher reproducibility at enhancement grade 1 and 2 images than at unenhanced images. So did the landmark of posterior nasal spine at enhancement grade 1 images, and the landmark of menton at enhancement grade 2, 3 and 4 images respectively. The above results suggest that the reproducibility of some landmarks can be increased by radiographic image enhancement during the identification of the lateral cephalometric landmarks on the monitor.
Radiographic Image Enhancement* ; Spine

PURPOSE: This study evaluated the diagnostic accuracy of the reverse contrast mode in intraoral digital radiography for the detection of proximal dentinal caries, in comparison with the original digital radiographs. MATERIALS AND METHODS: Eighty extracted premolars with no clinically apparent caries were selected, and digital radiographs of them were taken separately in standard conditions. Four observers examined the original radiographs and the same radiographs in the reverse contrast mode with the goal of identifying proximal dentinal caries. Microscopic sections 5 microm in thickness were prepared from the teeth in the mesiodistal direction. Four slides prepared from each sample used as the diagnostic gold standard. The data were analyzed using SPSS (alpha=0.05). RESULTS: Our results showed that the original radiographs in order to identify proximal dentinal caries had the following values for sensitivity, specificity, positive predictive value, negative predictive value, and accuracy, respectively: 72.5%, 90%, 87.2%, 76.5%, and 80.9%. For the reverse contrast mode, however, the corresponding values were 63.1%, 89.4%, 87.1%, 73.5%, and 78.8%, respectively. The sensitivity of original digital radiograph for detecting proximal dentinal caries was significantly higher than that of reverse contrast mode (p<0.05). However, no statistically significant differences were found regarding specificity, positive predictive value, negative predictive value, or accuracy (p>0.05). CONCLUSION: The sensitivity of the original digital radiograph for detecting proximal dentinal caries was significantly higher than that of the reversed contrast images. However, no statistically significant differences were found between these techniques regarding specificity, positive predictive value, negative predictive value, or accuracy.
Bicuspid ; Dental Caries ; Dentin* ; Image Enhancement ; Image Processing, Computer-Assisted ; Radiographic Image Enhancement* ; Radiography, Dental, Digital ; Sensitivity and Specificity ; Tooth

OBJECTIVE: In order to obtain more decision information from Digital Radiography(DR) images, an improved image enhancement algorithm is proposed based on the algorithm of Gauss-Laplacian pyramid. METHODS: The original algorithm is improved on the basis of the human visual characteristics and better enhancements, the low frequency components of the image is histogram equalized to make the image gray scale more balanced, and the high frequency component is enhanced by a hierarchical exponential enhancement to make the details of the image clearer. RESULTS: The improved algorithm improves the contrast of DR images in chest, pelvic and spine, and makes the image more layered and obtains good image enhancement effect. CONCLUSIONS The results show that the improved algorithm is superior to the traditional algorithm in terms of image enhancement.
Algorithms ; Humans ; Image Enhancement ; Radiographic Image Enhancement

In this paper are analyzed the disadvantages of CGO-3000 digital subtraction angiography table Operating Box. The authors put forward a communication control scheme between single-chip microcomputer(SCM) and programmable logic controller(PLC). The details of hardware and software of communication are given.
Angiography, Digital Subtraction ; instrumentation ; Equipment Design ; Humans ; Image Processing, Computer-Assisted ; instrumentation ; Microcomputers ; Radiographic Image Enhancement ; instrumentation ; Software

OBJECTIVETo compare the feasibility of bone and calcified plaque subtracted dual-energy CT angiography (CTA) with time of flight magnetic resonance angiography (TOF MRA) in evaluation of internal carotid artery atherosclerosis.

METHODSTotally 32 patients received a dual-energy CTA scan, along with a cerebral TOF MRA scan before or after CTA examination from one day to one month. Dual-energy software was used for bone and calcified plaque subtraction. Five anatomical segments were described for each internal carotid artery according to Fischer (1938). Ratings were based on a 1-4 scale for the dual-energy CTA maximum intensity projection (MIP) image: 1 not diagnostic, 2 partially diagnostic, 3 diagnostic, and 4 excellent. Lesions were categorized as mild (0-29%), moderate (30%-69%), severe (70%-99%), or occluded (no flow detected). Stenosis of internal carotid artery was evaluated based on post-subtracted CTA images and TOF MRA images.

RESULTSIn 320 arterial segments, 99% of arterial segments were > or = 3 score. Grading of stenosis on dual-energy CTA agreed with grading of stenoses on MRA images in 98% of arteries. In the mild and occlusion group, the agreement was 100% respectively. In the moderate and severe group, dual-energy CTA showed more severe stenosis than MRA in 7 vessels and there was significant difference between the results from the two different modalities (Z = -3.071, P = 0.002).

CONCLUSIONDual-energy CTA can be used to assess the stenosis of internal arteries around skull base, but may exaggerate the severe stenosis of cerebral arteries compared with TOF MRA.

Aged ; Angiography, Digital Subtraction ; methods ; Carotid Artery, Internal ; pathology ; Carotid Stenosis ; diagnosis ; Cerebral Angiography ; methods ; Cerebral Arteries ; diagnostic imaging ; pathology ; Female ; Humans ; Intracranial Arteriosclerosis ; diagnosis ; Magnetic Resonance Angiography ; Male ; Middle Aged ; Radiographic Image Enhancement ; methods ; Tomography, X-Ray Computed ; methods