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At least 145 records · Page 8Linked to original sources
PubMed1994

The value of functional computed tomography in the evaluation of soft-tissue injury in the upper cervical spine.

A functional rotatory computed tomography (CT) study of 423 whiplash patients with cervical spine soft-tissue injury was undertaken to determine its diagnostic value. The results are correlated with previous CT studies on normal subjects, and an evaluation of paradox motion, in which the lower vertebra rotates more than the vertebra immediately superior to it, is given. Asymmetrical left/right rotation reached the pathological value in 36% of the patient population at the level of C0-1. Twice as many patients had hypermobile rotation to the left as compared with the right, perhaps indicating that the right alar ligament is more often damaged in injuries involving the whiplash mechanism. A higher percentage of pathological values for hypermobile rotation was found at the level of C0-1 than at C1-2. Patients exhibiting paradox rotation had a significantly higher amount of rotation to the contralateral side than did those who exhibited no paradox rotation. These findings validate the use of functional rotatory CT in the evaluation of soft-tissue damage of the upper cervical spine resulting from whiplash injury.

Adolescent↗
PubMed1992

The reliability of computerized cephalometric soft tissue prediction following bimaxillary anterior subapical osteotomy.

The accuracy of predicting the results of orthodontic-surgical treatment following bimaxillary anterior subapical setback osteotomy was analyzed retrospectively. Comparisons of pretreatment prediction tracings of the lateral cephalograms with the 6-month postsurgical cephalograms of 38 patients showed that there was no statistically significant difference between the actual and predicted dentoalveolar setback in both arches. The computer-generated soft tissue predictions were generally accurate, with the exception of the horizontal position of the lower lip, which was underestimated, and, to a lesser extent, the vertical position of the upper lip, which was also underestimated. Computerized cephalometric prediction following bimaxillary anterior subapical osteotomy is sufficiently accurate to be of value to be used routinely in treatment planning for the horizontal upper lip prediction, but some modifications are advisable to obtain a more accurate horizontal lower lip prediction.

Adult↗
PubMed1981

The extremity soft-tissue lesion: a comparative study of ultrasound, computed tomography, and xeroradiography.

Twenty-five extremity soft-tissue lesions were evaluated by ultrasound (US), computed tomography (CT), and xeroradiography (XR). The lesion was detected by CT in 20 of 25 cases. In five cases, a soft-tissue tumor was not identified by CT due to small lesion size, isodensity, or the inability to distinguish scar tissue from recurrent tumor. Of the three modalities, the vascular bundle was most reliably defined by CT. In 20 of 25 cases, the lesion was detected by XR, but the size was accurately determined in only 13 cases.

Adolescent↗
PubMed1996

The conformity of a soft contact lens on the eye.

An axisymmetric elastic shell deformation model has been created to predict the conformity of a soft contact lens when pressed against the eye. Regions of contact and gap may be predicted, and the nonuniform reaction pressure between the lens and eye may also be found. This is important for issues like abrasion and comfort. Bending, membrane and transverse shear loads within the lens are also computed. Commercial soft contact lenses and a representative eye shape are used for the examples. We find that the uniformity of loading against the eye is strongly affected by the degree to which the lens is shaped to fit the eye, and relatively unaffected by the thickness of the lens.

Contact Lenses, Hydrophilic↗
PubMed2000

Structure-based estimation of enzymatic hydrolysis rates and its application in computer-aided retrometabolic drug design.

After a brief review of the problems related to the description of enzymatic hydrolysis rates and the quantification of steric effects, a recently developed method that uses the inaccessible solid angle omega h calculated around different atoms as a novel steric parameter to estimate human blood in vitro enzymatic hydrolysis rates in noncongener ester series is summarized. Some illustrative results obtained by the integration of this method into the expert system developed for computer-aided soft drug design are also presented. Starting from a lead compound, the system can provide full libraries of possible new "soft" molecular structures, a ranking order of these candidates based on isosteric-isoelectronic analogy to the lead, and estimated hydrolytic half-lives for all structures of interest.

Animals↗
PubMed2003

Acute cerebral infarction: effect of JPEG compression on detection at CT.

PURPOSE: To evaluate the effect of Joint Photographic Experts Group (JPEG) compression ratios of 10:1 and 20:1 on detection of acute cerebral infarction at computed tomography (CT). MATERIALS AND METHODS: CT images obtained in 25 patients with acute cerebral infarction and 25 patients with no lesions were compressed by means of a JPEG algorithm at ratios of 10:1 and 20:1. Normal and abnormal sections (on original and compressed images) were reviewed by using a color soft-copy computed monochrome cathode ray tube monitor. Five observers rated the presence or absence of a lesion with a 50-point scale (0, definitely absent; 25, equivocal; and 50, definitely present). Diagnostic accuracy was evaluated with receiver operating characteristic (ROC) curve analysis. Significant difference was defined as a P value less than.05 for the area tested with a two-tailed paired Student t test. RESULTS: At ROC analysis, no statistically significant difference was detected for all cases considered together (Az [area under the ROC curve] = 0.887 +/- 0.038 [mean +/- SD] on noncompressed images, Az = 0.897 +/- 0.038 on 10:1 compressed images, and Az = 0.842 +/- 0.073 on 20:1 compressed images; P >.05). CONCLUSION: JPEG compression at ratios of 10:1 and 20:1 was tolerated in the detection of acute cerebral infarction at CT.

Acute Disease↗
PubMed2006

An imaging-based computational approach to model ventilation distribution and soft-tissue deformation in the ovine lung.

RATIONALE AND OBJECTIVES: A computational modeling framework of soft-tissue mechanics and air flow has been developed toward the aim of linking computed tomography measures of ventilation distribution to subject-specific predictions in imaging-based geometric models of the lung. The aim of this approach is to enable predictions of the effect of perturbations in geometry or functional parameters on imaged function of the lung. MATERIALS AND METHODS: Computational techniques that can deal with anatomic detail and spatially distributed nonlinear material properties are used to model parenchymal soft-tissue mechanics in a physically realistic model of the ovine lung. The lung is modeled as a homogeneous, compressible, nonlinearly elastic body. Using equations for large deformation mechanics, change in geometry of the lung is simulated at static inflation pressures from 25 cm H2O to 0 cm H2O. Multidetector row computed tomography imaging defines the model geometry, the movement of the model lung surface during inflation, and displacement of airway bifurcations for comparison with predicted internal displacements of the model. RESULTS: A novel modeling framework has been formulated that links equations for large deformation of the lung tissue to equations for airway flow and pressure. This preliminary model predicts airway displacements that are in good agreement with imaged displacements (total root mean square [RMS] error < 4 mm from 25 to 0 cm H2O). CONCLUSIONS: State-of-the-art computed tomography imaging is interpreted using a modeling framework to predict ventilation distribution and changes in the geometry of the lung during increments in inflation pressure. Further development will provide a predictive link between subject-specific anatomy and function.

Algorithms↗
PubMed1995

A computer assisted photogrammetric analysis of soft tissue changes after orthodontic treatment. Part II: Results.

The purpose of this study was to use standardized facial photographs to compare the soft tissue profile changes in persons with Class II, Division 1 malocclusions who were treated with either an extraction or a nonextraction treatment modalities. Ninety-one patients (44 extraction and 47 nonextraction) were evaluated using standardized facial photographs, available at pretreatment, posttreatment and 2-years in retention. The photographs were digitized and displayed on a computer monitor. Thirty-eight landmarks (18 frontal and 20 lateral) were located. From these landmarks, 29 angular and linear dimensions (8 frontal and 21 lateral) were constructed. Descriptive and analytical statistics were used to compare the absolute dimensions, as well as the incremental changes, between the extraction and nonextraction groups. The present findings indicate: (1) After treatment the upper and lower lips were retracted significantly more in the extraction group compared with the nonextraction group. These differences persisted into retention. (2) The upper lip length increased more among subjects who were treated without extractions. (3) The upper vermilion height in male subjects and the upper and lower vermilion heights in female subjects increased among subjects who were treated without extractions and decreased among subjects who were treated with four first premolar extractions. (4) The nasolabial angle became significantly more obtuse among the female subjects who were treated with four first premolar extractions.

Bicuspid↗
PubMed1995

A computer assisted photogrammetric analysis of soft tissue changes after orthodontic treatment. Part I: Methodology and reliability.

The purpose of this study was to use standardized facial photographs to compare the soft tissue profile changes in persons with Class II, Division 1 malocclusions who were treated with either an extraction or a nonextraction treatment modality. Ninety-one patients (44 extraction and 47 nonextraction) were evaluated with standardized facial photographs, available at pretreatment, posttreatment, and 2 years in retention. The photographs were digitized and displayed on a computer monitor. Thirty-eight landmarks (18 frontal and 20 lateral) were located. From these landmarks, 29 angular and linear dimensions (8 frontal and 21 lateral) were constructed. Descriptive and analytical statistics were used to compare the absolute dimensions, as well as the incremental changes, between the extraction and nonextraction groups. The present findings indicate that (1) Photographs allow for measurement of structures from a profile, as well as frontal orientations. (2) Measurement of profile changes from facial photographs appear to be fairly reliable but also have significant limitations. (3) Certain landmarks tended to be less reliable than others, e.g., subnasale and gnathion. In general, measurements from frontal photographs were more reliable than those obtained from lateral photographs and linear measurements were more reliable than angular measurements. (4) Changes in head posture within the cephalostat have an impact on vertical facial dimensions measured from frontal photographs. Horizontal dimensions were effected to a lesser degree. (5) Facial structures that lie closer to the camera appeared to be relatively larger than structures located farther from the camera. (6) The overall process of evaluating facial changes from photographs is both technique and operator sensitive. (7) More research specifically testing the photogrammetric method in a clinical setting is needed.

Adolescent↗
PubMed1987

Magnetic resonance imaging versus computed tomography in the evaluation of soft tissue tumors of the extremities.

Twenty patients with extremity soft tissue tumors were prospectively evaluated with magnetic resonance imaging (MRI) and computed tomography (CT) scans with subsequent anatomic correlation of surgical findings. MRI and CT had a similar percentage of accuracy in assessing tumor relationship with major neurovascular (80% and 70%, respectively) and skeletal (80% and 75%, respectively) structures. MRI was significantly better than CT in displaying contrast between tumor and muscle when using the T2 weighted spin echo (SE) (p2 less than 0.002) and inversion recovery (IR) (p2 less than 0.005) pulse sequences. MRI and CT were comparable in demonstrating contrast between tumor and fat. The contrast between tumor and vessel was better displayed by MRI compared with CT when using the T1 weighted SE (p2 less than 0.001) and T2 weighted SE (p2 less than 0.001) pulse sequences. T1 and T2 values were measured on fresh tumor and normal tissue samples and were used to predict relative contrast on different MRI pulse sequences using isosignal contour plots. MRI appears to offer several advantages over CT in the evaluation of extremity soft tissue tumors.

Arm↗
PubMed1979

Use of computed tomography in diagnosis of soft-tissue tumors.

Soft-tissue tumors can evade the usual diagnostic methods. In the case presented, computed tomography proved to be the best diagnostic tool in demonstrating a malignant extranodal lymphoma. Computed tomography is useful not only in detecting a tumor but also in determining its extent. This aids the surgeon in selecting and conducting the most appropriate operation.

Abdominal Neoplasms↗
PubMedDate not supplied

Computed tomography of pelvic lipomatosis. Report of a case.

Pelvic lipomatosis is a non-malignant condition of unknown etiology characterized by an overgrowth of non-encapsulated fatty tissue in the perirectal and perivesical spaces of the pelvis. The symptoms are generally vague and the condition is often diagnosed accidentally. It may cause obstruction of the ureters, inferior vena cava and pelvic veins and may be associated with cystitis glandularis. The typical conventional radiographic findings, though not pathognomonic, are a high-positioned and pear-shaped bladder, tubular narrowing of the rectum and distal sigmoid colon and reduced attenuation of the pelvic soft tissues. Computed tomography demonstrates a non-encapsulated fatty mass surrounding the pelvic organs symmetrically and with an attenuation similar to that of subcutaneous fat. The fatty tissue may contain strands with a higher attenuation than that of fat. The findings at computed tomography seem to be pathognomonic for this condition and eliminate the need for routine surgical biopsies.

Adult↗
PubMed2026

Artificial Intelligence for Colorectal Surgeons-Part II: Research Applications, Challenges in Adoption, and Practical Resources.

BACKGROUND: This is part II of a 2-part series examining artificial intelligence in colorectal surgery. Part I established foundational concepts and clinical applications. Implementation, however, requires understanding research methodologies, available resources, and the specific challenges currently limiting widespread adoption. These topics are the focus of part II. OBJECTIVE: To examine artificial intelligence's transformation of surgical research, provide practical implementation resources, address adoption challenges, and explore future directions in colorectal surgery. METHODS: Comprehensive literature review focusing on artificial intelligence research methodology, implementation barriers, educational resources, and emerging technologies relevant to colorectal surgeons. RESULTS: Artificial intelligence streamlines clinical trial design through predictive modeling and natural language processing, reducing enrollment challenges that contribute to failed or inadequate trial accrual. Machine learning enables heterogeneity analysis within clinical trials, identifying treatment-responsive subgroups. Foundation models unlock analysis of unstructured electronic health record data at scale. Professional societies and universities offer specialized artificial intelligence education programs, with open-access data sets facilitating research participation. However, implementation faces multifaceted challenges: technical infrastructure demands, with real-time processing requiring dedicated graphics processing unit clusters; regulatory frameworks struggling with continuously evolving algorithms; undefined liability distribution for artificial intelligence-assisted decisions; algorithmic bias risking health care disparities; and the "black box" problem limiting clinical trust. Economic barriers include substantial initial costs without clear reimbursement pathways. Future directions include multimodal artificial intelligence integrating imaging, genomics, and histopathology; cognitive robotic systems with real-time decision support; digital twin technology for patient-specific surgical simulation; and global surgical artificial intelligence networks enabling distributed learning across institutions. CONCLUSIONS: Although artificial intelligence offers transformative potential for colorectal surgery research and practice, successful implementation requires addressing technical, regulatory, ethical, and economic challenges. The surgeon's evolving role demands both traditional expertise and computational fluency. Future advances in multimodal integration, autonomous systems, and global collaboration will fundamentally reshape surgical practice but will require thoughtful implementation prioritizing patient benefit and clinical value.

Humans↗
PubMed1984

Aortoesophageal fistula after perigraft abscess with characteristic CT findings.

Aortoesophageal fistula is a rare cause of massive gastrointestinal hemorrhage, and may occur as a sequela to prosthetic replacement of the thoracic aorta. Esophageal compression necrosis with leakage of microorganisms into the proximal suture line is probably central to pathogenesis. Like the more common aortoduodenal fistula, diagnosis by traditional radiographic and endoscopic methods is difficult. We report here such a fistula, in which computed tomographic soft tissue abnormalities were characteristic of perigraft abscess; fistulization occurred subsequently. CT holds potential for being a sensitive study to show localized perivascular infection, an important precursor to aortoenteric fistula, and as such should be positive early in the development of a fistula.

Abscess↗
PubMed1998

Soft-copy sonography: cost reduction sensitivity analysis in a pediatric hospital.

OBJECTIVE: Our objective was to determine whether interpreting sonograms of pediatric patients using soft-copy (computer workstation) instead of laser-printed film could reduce costs for a pediatric radiology department. We used theoretic models of growth to analyze costs. MATERIALS AND METHODS: The costs of a sonographic picture archiving and communication system (three interface devices, two workstations, a network server, maintenance expenses, and storage media costs) were compared with the potential savings of eliminating film and increasing technologist efficiency or reducing the number of technologists. The model was based on historic trends and future capitation estimates that will reduce fee-for-service reimbursement. The effects of varying the study volume and reducing technologists' work hours were analyzed. RESULTS: By converting to soft-copy interpretation, we saved 6 min 32 sec per examination by eliminating film processing waiting time, thus reducing examination time from 30 min to 24 min. During an average day of 27 examinations, 176 min were saved. However, 33 min a day were spent retrieving prior studies from long-term storage; thus, 143 extra minutes a day were available for scanning. This improved efficiency could result in five more sonograms a day obtained by converting to soft-copy interpretation, using existing staff and equipment. Alternatively, five examinations a day would equate to one half of a full-time equivalent technologists position. Our analysis of costs considered that the hospital's anticipated growth of sonography and the depreciation of equipment during 5 years resulted in a savings of more than $606,000. Increasing the examinations by just 200 sonograms in the first year and no further growth resulted in a savings of more than $96,000. If the number of sonograms stayed constant, elimination of film printing alone resulted in a loss of approximately $157,000; reduction of one half of a full-time equivalent technologist's position would recuperate approximately $134,000 of that loss. CONCLUSION: Soft-copy sonography can save money through improved technologist efficiency, thereby increasing the number of sonograms obtained and revenue generated. If the number of sonograms does not increase, elimination of printing costs and reduction of staff technologists will not result in a savings.

Cost Savings↗
PubMed2001

A k-space method for large-scale models of wave propagation in tissue.

Large-scale simulation of ultrasonic pulse propagation in inhomogeneous tissue is important for the study of ultrasound-tissue interaction as well as for development of new imaging methods. Typical scales of interest span hundreds of wavelengths; most current two-dimensional methods, such as finite-difference and finite-element methods, are unable to compute propagation on this scale with the efficiency needed for imaging studies. Furthermore, for most available methods of simulating ultrasonic propagation, large-scale, three-dimensional computations of ultrasonic scattering are infeasible. Some of these difficulties have been overcome by previous pseudospectral and k-space methods, which allow substantial portions of the necessary computations to be executed using fast Fourier transforms. This paper presents a simplified derivation of the k-space method for a medium of variable sound speed and density; the derivation clearly shows the relationship of this k-space method to both past k-space methods and pseudospectral methods. In the present method, the spatial differential equations are solved by a simple Fourier transform method, and temporal iteration is performed using a k-t space propagator. The temporal iteration procedure is shown to be exact for homogeneous media, unconditionally stable for "slow" (c(x) < or = c0) media, and highly accurate for general weakly scattering media. The applicability of the k-space method to large-scale soft tissue modeling is shown by simulating two-dimensional propagation of an incident plane wave through several tissue-mimicking cylinders as well as a model chest wall cross section. A three-dimensional implementation of the k-space method is also employed for the example problem of propagation through a tissue-mimicking sphere. Numerical results indicate that the k-space method is accurate for large-scale soft tissue computations with much greater efficiency than that of an analogous leapfrog pseudospectral method or a 2-4 finite difference time-domain method. However, numerical results also indicate that the k-space method is less accurate than the finite-difference method for a high contrast scatterer with bone-like properties, although qualitative results can still be obtained by the k-space method with high efficiency. Possible extensions to the method, including representation of absorption effects, absorbing boundary conditions, elastic-wave propagation, and acoustic nonlinearity, are discussed.

Adipose Tissue↗
PubMed1981

Computed tomography in paleopathology: technique and case study.

With the development of computed tomography, soft tissues and foreign body collections are distinguished with remarkable resolution. This distinction is particularly useful when examining desiccated human remains, both in construction of research strategies and when invasive procedure (i.e., traditional autopsies, needle biopsies, etc.) are not possible. Though the organs differ markedly from living tissue, it is possible to distinguish major organs with some certainty. One case study exhibited three separate pathological conditions which were not demonstrated with traditional radiological procedures.

Female↗
PubMed2004

Accuracy of facial soft tissue thickness measurements in personal computer-based multiplanar reconstructed computed tomographic images.

The purpose of this study was to determine the precision and accuracy of facial soft tissue measurement using personal computer (PC)-based multiplanar reconstructed (MPR) computed tomography (CT) images and to evaluate the effect of the various CT scanning protocols on the facial soft tissue thickness measurement. Thirteen different CT imaging protocols were used to image a cadaver head. MPR reformations and three-dimensional (3D) reconstructions viewed on a laptop PC were used to make measurements at six specific sites on each set of images. These measurements were compared to physical measurements at the same sites. Increasing the slice thickness resulted in decreased image quality. Within the same slice thickness, increasing the pitch ratio in the spiral mode, resulted in decreasing image quality. The image quality of conventional CT scanning was relatively poorer than that of the spiral CT scanning. However, the mean deviation from the physical measurement was within 0.43 mm in every instance. This mean deviation was quite small and clinically acceptable for measuring the soft tissue thickness of the facial area. PC-based MPR CT images of the face using routine scanning CT protocols can be used to accurately measure soft tissue thickness in the facial region. However, for more fine and accurate data collection, scanning protocols with slice thicknesses less than 5mm, and a spiral/helical mode pitch less than 2:1 are recommended.

Cadaver↗