PURPOSE: The purpose of this study is to compare the performance of the T1 3D subtraction technique and the conventional 2D dynamic contrast enhancement (DCE) technique in diagnosing Cushing's disease. MATERIALS AND METHODS: Twelve patients with clinically and biochemically proven Cushing's disease were included in the study. In addition, 23 patients with a Rathke's cleft cyst (RCC) diagnosed on an MRI with normal pituitary hormone levels were included as a control, to prevent non-blinded positive results. Postcontrast T1 3D fast spin echo (FSE) images were acquired after DCE images in 3T MRI and image subtraction of pre- and postcontrast T1 3D FSE images were performed. Inter-observer agreement, interpretation time, multiobserver receiver operating characteristic (ROC), and net benefit analyses were performed to compare 2D DCE and T1 3D subtraction techniques. RESULTS: Inter-observer agreement for a visual scale of contrast enhancement was poor in DCE (κ = 0.57) and good in T1 3D subtraction images (κ = 0.75). The time taken for determining contrast-enhancement in pituitary lesions was significantly shorter in the T1 3D subtraction images compared to the DCE sequence (P < 0.05). ROC values demonstrated increased reader confidence range with T1 3D subtraction images (95% confidence interval [CI]: 0.94–1.00) compared with DCE (95% CI: 0.70–0.92) (P < 0.01). The net benefit effect of T1 3D subtraction images over DCE was 0.34 (95% CI: 0.12–0.56). For Cushing's disease, both reviewers misclassified one case as a nonenhancing lesion on the DCE images, while no cases were misclassified on T1 3D subtraction images. CONCLUSION: The T1 3D subtraction technique shows superior performance for determining the presence of enhancement on pituitary lesions compared with conventional DCE techniques, which may aid in diagnosing Cushing's disease.
Humans ; Magnetic Resonance Imaging ; ROC Curve ; Subtraction Technique

PURPOSE: Erosions and osteophytes are radiographic characteristics that are found in different stages of temporomandibular joint (TMJ) osteoarthritis. This study assessed the effectiveness of digital subtraction radiography (DSR) in diagnosing simulated osteophytes and erosions in the TMJ. MATERIALS AND METHODS: Five intact, dry human skulls were used to assess the effectiveness of DSR in detecting osteophytes. Four cortical bone chips of varying thicknesses (0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm) were placed at the medial, central, and lateral aspects of the condyle anterior surface. Two defects of varying depth (1.0 mm and 1.5 mm) were created on the lateral, central, and medial poles of the condyles of 2 skulls to simulate erosions. Panoramic images of the condyles were acquired before and after artificially creating the changes. Digital subtraction was performed with Emago dental image archiving software. Five observers familiar with the interpretation of TMJ radiographs evaluated the images. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of the imaging methods. RESULTS: The area under the ROC curve (Az) value for the overall diagnostic accuracy of DSR in detecting osteophytic changes was 0.931. The Az value for the overall diagnostic accuracy of panoramic imaging was 0.695. The accuracy of DSR in detecting erosive changes was 0.854 and 0.696 for panoramic imaging. DSR was remarkably more accurate than panoramic imaging in detecting simulated osteophytic and erosive changes. CONCLUSION: The accuracy of panoramic imaging in detecting degenerative changes was significantly lower than the accuracy of DSR (P<.05). DSR improved the accuracy of detection using panoramic images.
Humans ; Osteoarthritis ; Osteophyte* ; Radiography* ; Radiography, Panoramic ; ROC Curve ; Skull ; Subtraction Technique ; Temporomandibular Joint*

PURPOSE: This study employed a posteriori registration and subtraction of radiographic images to quantify the apical root resorption in maxillary permanent central incisors after orthodontic treatment, and assessed whether the external apical root resorption (EARR) was related to a range of parameters involved in the treatment. MATERIALS AND METHODS: A sample of 79 patients (mean age, 13.5±2.2 years) with no history of trauma or endodontic treatment of the maxillary permanent central incisors was selected. Periapical radiographs taken before and after orthodontic treatment were digitized and imported to the Regeemy software. Based on an analysis of the posttreatment radiographs, the length of the incisors was measured using Image J software. The mean EARR was described in pixels and relative root resorption (%). The patient's age and gender, tooth extraction, use of elastics, and treatment duration were evaluated to identify possible correlations with EARR. RESULTS: The mean EARR observed was 15.44±12.1 pixels (5.1% resorption). No differences in the mean EARR were observed according to patient characteristics (gender, age) or treatment parameters (use of elastics, treatment duration). The only parameter that influenced the mean EARR of a patient was the need for tooth extraction. CONCLUSION: A posteriori registration and subtraction of periapical radiographs was a suitable method to quantify EARR after orthodontic treatment, and the need for tooth extraction increased the extent of root resorption after orthodontic treatment.
Humans ; Image Processing, Computer-Assisted ; Incisor ; Orthodontics ; Root Resorption* ; Subtraction Technique ; Tooth Extraction

OBJECTIVE: We aimed to evaluate the use of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) at 3.0 T for differentiating the benign from malignant soft tissue tumors. Also we aimed to assess whether the shorter length of DCE-MRI protocols are adequate, and to evaluate the effect of temporal resolution. MATERIALS AND METHODS: Dynamic contrast-enhanced magnetic resonance imaging, at 3.0 T with a 1 second temporal resolution in 13 patients with pathologically confirmed soft tissue tumors, was analyzed. Visual assessment of time-signal curves, subtraction images, maximal relative enhancement at the first (maximal peak enhancement [Emax]/1) and second (Emax/2) minutes, Emax, steepest slope calculated by using various time intervals (5, 30, 60 seconds), and the start of dynamic enhancement were analyzed. RESULTS: The 13 tumors were comprised of seven benign and six malignant soft tissue neoplasms. Washout on time-signal curves was seen on three (50%) malignant tumors and one (14%) benign one. The most discriminating DCE-MRI parameter was the steepest slope calculated, by using at 5-second intervals, followed by Emax/1 and Emax/2. All of the steepest slope values occurred within 2 minutes of the dynamic study. Start of dynamic enhancement did not show a significant difference, but no malignant tumor rendered a value greater than 14 seconds. CONCLUSION: The steepest slope and early relative enhancement have the potential for differentiating benign from malignant soft tissue tumors. Short-length rather than long-length DCE-MRI protocol may be adequate for our purpose. The steepest slope parameters require a short temporal resolution, while maximal peak enhancement parameter may be more optimal for a longer temporal resolution.
Adult ; Aged ; Aged, 80 and over ; Contrast Media/diagnostic use ; Diagnosis, Differential ; Female ; Gadolinium DTPA/diagnostic use ; Humans ; Image Interpretation, Computer-Assisted/methods ; Magnetic Resonance Imaging/*methods ; Male ; Middle Aged ; Soft Tissue Neoplasms/*pathology ; Statistics, Nonparametric ; Subtraction Technique

The long-period CT perfusion imaging leads to an excess amount of radiation dose to the patient. However, the radiation dose could be significantly reduced if a previous normal-dose image is acquired before a set of low-dose scans of perfusion, and a filtering processing is performed on the differences between the current low-dose images and the previous normal-dose image, then the results are added to the previous image. But the selection of plenty of parameters makes the algorithm complicated. This paper proposes an innovative approach performed in sinogram domain instead of in image domain. First a normal-dose image and a set of low-dose projection data are acquired before the perfusion. Second the perfusion information is commendably reconstructed with sparsity constraints of the differences between current low-dose perfusion sinograms and previous low-dose sinogram. Finally, the reconstructed perfusion information is added to the previous normal-dose image. The proposed method was validated by simulated experiments with a set of brain CT perfusion images, which showed that the new method provided more accurate perfusion information; the time-attenuation curve was more close to that for normal-dose scan and the mean transit time more repeatable.
Algorithms ; Brain ; diagnostic imaging ; Humans ; Perfusion Imaging ; methods ; Radiation Dosage ; Radiation Injuries ; etiology ; prevention & control ; Radiographic Image Interpretation, Computer-Assisted ; Subtraction Technique ; Tomography, X-Ray Computed ; adverse effects ; methods

OBJECTIVE: To investigate the clinical feasibility of dual energy subtraction (DES) imaging to improve the delineation of the vocal cord and diagnostic accuracy of vocal cord paralysis as compared with the anterior-posterior view of flat panel detector (FPD) neck radiography. MATERIALS AND METHODS: For 122 consecutive patients who underwent both a flexible laryngoscopy and conventional/DES FPD radiography, three blinded readers retrospectively graded the radiographs during phonation and inspiration on a scale of 1 (poor) to 5 (excellent) for the delineation of the vocal cord, and in consensus, reviewed the diagnostic accuracy of vocal cord paralysis employing the laryngoscopy as the reference. We compared vocal cord delineation scores and accuracy of vocal cord paralysis diagnosis by both conventional and DES techniques using kappa statistics and assessing the area under the receiver operating characteristic curve (AUC). RESULTS: Vocal cord delineation scores by DES (mean, 4.2 +/- 0.4) were significantly higher than those by conventional imaging (mean, 3.3 +/- 0.5) (p < 0.0001). Sensitivity for diagnosing vocal cord paralysis by the conventional technique was 25%, whereas the specificity was 94%. Sensitivity by DES was 75%, whereas the specificity was 96%. The diagnostic accuracy by DES was significantly superior (kappa = 0.60, AUC = 0.909) to that by conventional technique (kappa = 0.18, AUC = 0.852) (p = 0.038). CONCLUSION: Dual energy subtraction is a superior method compared to the conventional FPD radiography for delineating the vocal cord and accurately diagnosing vocal cord paralysis.
Absorptiometry, Photon/*instrumentation/*methods ; Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; Feasibility Studies ; Female ; Humans ; Male ; Middle Aged ; Observer Variation ; Reproducibility of Results ; Sensitivity and Specificity ; Subtraction Technique ; Vocal Cord Paralysis/*radiography ; Vocal Cords/radiography ; *X-Ray Intensifying Screens ; Young Adult

Local maxima in multimodality image registration based on mutual information is discussed in this paper. Particle swarm optimization (PSO) and filter preprocessing based on hamming window is used to search the registration parameters. Simulations have been done to illustrate that after low-pass filter preprocessing local maxima is eliminated to a great extent. In most case the global maxima can be found by PSO. Simulations illustrate the efficiency and accuracy of this method in registration strategy.
Algorithms ; Artifacts ; Diagnostic Imaging ; methods ; Humans ; Image Enhancement ; methods ; Image Processing, Computer-Assisted ; methods ; Subtraction Technique

In this paper, a method based on fuzzy mathematics to fuse multimodality medical images was presented. The improved FCM algorithm was adopted to segment images, and automatic fuzzy redistribution algorithm to define the subject degree. 16 different combinations of image tissues and 16 context relations, 256 models altogether, were considered. The result showed that the method had the great ability of anti-error and anti-segmentation interference and had the characteristics of robustness, quickness, and accuracy.
Algorithms ; Fuzzy Logic ; Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; methods ; Magnetic Resonance Imaging ; methods ; Pattern Recognition, Automated ; methods ; Positron-Emission Tomography ; methods ; Subtraction Technique

In this paper, CT/PET multimodality medical image registration is performed by a region similarity measure (RSM), accompanied with an improved segment method and Powell optimization algorithm. RSM has been proved to be a quick, accurate and robust algorithm by the experimental results.
Algorithms ; Artificial Intelligence ; Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; methods ; Imaging, Three-Dimensional ; methods ; Positron-Emission Tomography ; instrumentation ; methods ; Sensitivity and Specificity ; Subtraction Technique ; Systems Integration ; Tomography, X-Ray Computed ; instrumentation ; methods

In this paper, we discuss image fusion methods within the space domain, transform domain and intelligence domain, where the emphasis is given to the fusion method based on image segment, wavelet transform, its extension, and semantic predication. Finally, some remarks upon prospects of medical image fusion are presented.
Algorithms ; Artificial Intelligence ; Diagnostic Imaging ; methods ; Image Interpretation, Computer-Assisted ; methods ; Subtraction Technique