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A 53-year-old man, a known alcoholic, was admitted to hospital, because of abdominal swelling, with the admission diagnosis of ascites. Treated with diuretics a severe hypokalaemia developed with subileus and moderate clouding of consciousness. Computed tomography revealed the correct diagnosis of intraabdominal extraperitoneal (mesenteric, pelvic, retroperitoneal) soft-tissue lipomatosis.
Forty-seven patients with sacroiliac joint abnormalities were examined with computed tomography and conventional complex-motion tomography. Twenty-nine patients had spondyloarthritis. Of the 29, complex-motion tomography detected bone erosions in 16 patients, whereas computed tomography revealed erosions in nine. Computed tomography was more sensitive in detection of joint narrowing, joint widening, osteosclerosis, and intraarticular bony ankylosis. In the remaining 13 patients, computed tomography was the modality of choice in detection of paraarticular soft tissue pathology, such as abscess or tumor, and in detection of the lesions involving the sacral canal and neural foramina.
The external auditory canal, middle ear, and bulk of the ossicular chain develop from the first branchial groove, first and second branchial arches, and first pharyngeal pouch. Embryologic development of these structures is complex and only rarely are two anomalies identical. Development of the inner ear structures occurs independently of external ear structures, and concomitant involvement is unusual. This study includes 11 cases of unilateral external auditory canal atresia and two cases of bilateral atresia. Eight cases (four bilateral) of isolated congenital ossicular anomalies are also included. Emphasis is placed on findings of surgical import. All patients were studied with computed tomography only, because it was believed that the bony and soft-tissue detail achieved is superior to that with conventional multidirectional tomography.
Quantitative assessment of the biomechanical properties of limb soft tissues has become more important during the last decade because of the introduction of computer-aided design and computer-aided manufacturing (CAD/CAM) and finite element analysis to the prosthetic socket design. Because of the lack of a clinically easy-to-use apparatus, the site and posture dependences of the material properties of lower limb soft tissues have not been fully reported in the literature. In this study, an ultrasound indentation system with a pen-size hand-held probe developed earlier by the authors was used to obtain the indentation responses of lower limb soft tissues. Indentation tests were conducted on normal young subjects with four females and four males at four sites with three body postures. A linear elastic indentation solution was used to extract the effective Young's modulus from the indentation responses. The determined modulus ranged from 10.4 to 89.2 kPa for the soft tissues tested. These results were in a similar range as those reported in the literature. The thickness of the lower limb soft tissues varied slightly with body posture changes. The Young's modulus determined was demonstrated to be significantly dependent on site, posture, subject and gender. The overall mean modulus of male subjects was 40% larger than that of female subjects. No significant correlation was established between the effective Young's modulus and the thickness of entire soft tissue layers.
Leiomyosarcomas (LS) are relatively uncommon soft-tissue sarcomas that occasionally involve the extremities. LS are usually tumors of adults and most often involve the gastrointestinal tract and uterus. When a soft-tissue sarcoma is suspected, comprehensive preoperative staging studies are an important part of the diagnostic and therapeutic management. With the use of computed tomography and magnetic resonance image scanning, the role of the arteriogram in the staging of soft-tissue tumors has been markedly diminished. There is still, however, a place for the arteriogram in the staging of soft-tissue tumors that are proximate to or displace the neurovascular bundle. Two patients demonstrated LS that arose from the popliteal artery, illustrating the importance of arteriography. When indentation and displacement can be visualized, involvement of the artery should be suspected. This may be critical when considering limb salvage versus amputation surgery. If limb salvage surgery is to be accomplished, an interpositional graft and segmental resection of the artery are necessary.
Recent developments in computer-aided medical imaging coupled with the related emergence of computer-aided design and manufacturing technology have had a significant effect on our management of patients with congenital and acquired head and neck deformities. In our institution, plain film skull radiography, cephalometry, and pluridirectional tomography have been largely replaced by high-resolution CT scanning augmented by planar reformations and three-dimensional surface reconstructions. A sophisticated computer-assisted radiologic imaging unit has been established to assist the surgeon and researcher. This marriage of advanced radiographic techniques, industrial computer-aided design technology, and clinical surgery have allowed us to better define aberrant anatomy, design new operative solutions for familiar as well as unusual problems, and quantitate changes of surgery and growth over time.
Elastofibroma dorsi is a pseudotumorous connective tissue mass that characteristically arises between the chest wall and the inferior angle of the scapula. Its long axis is typically craniocaudal. Two patients are illustrated, each presenting with a fixed subscapular mass. Computed tomography showed each mass as elongated, incompletely marginated, and of soft tissue density deep to the inferior angle of a scapula. The latissimus dorsi and an underlying layer of fat were posterolaterally elevated inferior to the tip of the scapula. After incisional biopsy excluded sarcoma, each mass was locally excised.
A new method is presented for the modeling of the electron (positron) energy-loss straggling in Monte Carlo transport simulations. First, the Vavilov energy-loss distribution is calculated for electrons and positrons using the Møller and Bhabha collision cross-sections, respectively. The maximum energy transfer in a single collision (E(S)) is considered as variable. Binding effects from low-energy collisions are modeled using the Blunck and Westphal model. Secondly, new algorithms are developed to fit the Vavilov distribution. These algorithms are based on the first three moments of the energy-loss distribution. They are suitable for rapid random sampling of the energy loss. The new algorithms are validated against the Vavilov distribution for electrons and positrons, water and lead, kinetic energy E0 of 0.1, 1, and 10 MeV and several values of E(S) (10, 50, 100, and 200 keV). The developed algorithms are incorporated in a new version of the GEPTS Monte Carlo code called GEPTS(III). Collisions involving energy transfers larger than E(S) are simulated individually and the energy loss due to soft collisions (energy transfers less than E(S)) is sampled using the new algorithms. The straggling effect is therefore taken into account whatever the chosen E(S) value. GEPTS(III) and EGSnrc are used for the calculation of (1) electron dose distributions in water and (2) energy spectra for electrons passing through water and tungsten slabs. Electron beams of 1, 2, 5, 10, and 20 MeV along with varying E(S) values are considered. Electron dose distributions in water are rather insensitive to the soft collision straggling. The use of the new algorithms results in a slight gain in computation time when relatively large E(S) values are used (e.g., E(S) = 1 MeV for 10 MeV electrons). However, the calculation of electron energy spectra is very sensitive to the soft collision straggling. GEPTS(III) (E(S) = 200 keV) is about 5 and 11 times faster than EGSnrc (E(S) = 1 keV) for the case of 2 and 20 MeV electrons passing through 0.025 and 0.25 cm water slabs, respectively. Contrary to EGSnrc, GEPTS(III) accounts for the energy-spectrum broadening due to the binding effects. The resulting differences between the two codes are significant for 5 and 10 MeV electrons passing through a 0.01 cm tungsten slab. Gains in GEPTS(III) computation times (approximately a factor 5) are also observed for tungsten. In short, GEPTS(III) provides significant advantages (rapidity and accuracy) for electron transport simulations, especially those dealing with energy-spectrum calculations, as encountered in clinical electron beam modeling studies. In other respects, the developed approach is more suitable than class-II codes for the use of accurate electron cross sections (numerical data) at low energy (<100 keV).
We retrospectively reviewed the use of computed tomography scans for the preoperative evaluation of musculoskeletal neoplasms in nineteen children. Of twenty-five scans, there was accurate correlation with the surgical findings in thirteen patients (fourteen scans), while overestimation or underestimation of the extent of soft-tissue disease was evident in nine patients (eleven scans). We concluded that computed tomography is a useful adjunct to the more conventional means of preoperative assessment but that overdependence on this one method of evaluation should be avoided.
Anatomical localisation of intramuscular haematomas can be achieved more accurately by computer tomography than by clinical examination in conjunction with conventional radiography. Computer tomography is able to demonstrate fresh haematomas before they become diagnosable clinically, and before secondary changes, such as calcification or bone erosions, make them visible on conventional radiographs. In this way the diagnosis is made more certain and the choice between conservative or surgical treatment is simplified. Ther period of treatment with clotting factors can, in some cases, be shortened as a result of serial examinations by computer tomography.
With digital transversal slice imaging (TSI) as a supplementary program to pantomographic devices and digital volume tomography (DVT), images of the viscerocranium are now possible in several planes. The two procedures, TSI and DVT, are complementary. They should be applied where the indication justifies it in dentistry and maxillofacial surgery for diagnostic and forensic purposes. To minimize patient exposure to radiation, computer tomography (CT) should only be used in complex situations of the viscerocranium where soft tissues are involved or in tumor diagnosis.
Positron emission tomography (PET) with fluorine-18 fluoro-2-deoxy-D-glucose (FDG) was performed in 19 patients referred for clinical evaluation of soft-tissue masses. These patients had 20 different lesions and had been evaluated previously with computed tomography (CT) and/or magnetic resonance (MR) imaging. The diagnoses were subsequently confirmed with open biopsy or excision (19 lesions) or by clinical and radiographic follow-up (one lesion). Semiquantitative assessment of FDG accumulation (differential uptake ratio) within the suspected tumor helped correctly separate the 10 malignant tumors from the 10 benign lesions. In contrast, a simple ratio of FDG uptake within the suspected tumor to that within comparable normal soft tissue was less successful in helping make this distinction, with overlap in 12 of the 20 cases. Careful comparison with findings from other available imaging studies is essential for accurate interpretation of PET studies of soft-tissue masses, but in many cases, PET may be a useful adjunct in the preoperative evaluation of suspected soft-tissue tumors, yielding valuable information that is not provided with CT or MR imaging.
BACKGROUND: Plantar ulcers produced by diabetic foot disease are devastating and costly. Better understanding of the ulcer-producing process is important to improve detection of feet that are at risk and to improve intervention. We identified and quantified soft-tissue and osseous structural changes in the forefoot of diabetic patients with a prior plantar ulcer. METHODS: Thirty-two individuals with a mean age (and standard deviation) of 57 +/- 11 years were studied; sixteen had diabetes (of a mean of 20 +/- 11 years' duration), peripheral neuropathy, and a prior plantar ulcer, and sixteen were matched controls. Computed tomography was used to evaluate forefoot structure, including the plantar soft-tissue (muscle) density, soft-tissue thickness beneath the metatarsal heads, metatarsophalangeal joint angle, metatarsal bone density, and metatarsophalangeal joint arthropathy. RESULTS: Plantar soft-tissue (muscle) density was lower in the individuals with diabetes (mean, 1 HU [Hounsfield unit]) than it was in the controls (mean, 18 HU). There was no difference in the soft-tissue thickness beneath the metatarsal heads (mean, 10 mm) between the individuals with diabetes and the controls, but the soft-tissue thickness decreased with age. The individuals with diabetes had greater extension deformity of the first, second, and third metatarsophalangeal joints and greater arthropathy of the second, third, and fourth metatarsophalangeal joints. There were no significant differences in metatarsal bone density between the groups. CONCLUSIONS: There were significant differences between the forefeet of individuals with diabetes and a previous plantar ulcer and those of controls: plantar muscle density was decreased, and metatarsophalangeal joint extension and arthropathy were increased. Interestingly, the soft-tissue thickness under the metatarsal heads in the controls was not greater than that in the diabetic patients. CLINICAL RELEVANCE: This study demonstrated structural differences between the forefeet of patients with diabetes and a previous ulcer and those of normal age-matched controls. The information can serve to guide new interventions to prevent or treat foot ulcerations in this patient population.
With the advent of computed tomography (CT) and magnetic resonance imaging (MRI), visualization of soft tissue structures in the spinal canal, which were previously undetectable, is possible. This study was undertaken to more accurately identify these soft tissue layers and to determine factors such as when is a disc contained and when is it not; in discography, when the disc leaks, into what layer is the contrast going; or when a nuclear fragment creeps upward or downward, just where is it. The works of Fick, Dommisse, Kikuchi, Schellinger, Hofmann, Batson, and Parke were studied. The professors of anatomy of four major medical schools were consulted along with several neuroradiologists and embryologists. Forty lumbar spines were dissected (20 fresh, 20 preserved). Magnetic resonance imaging scans were taken. Photographs and photomicrographs were made. A fibrous membrane, first mentioned by Fick, can be identified lying anterior to the posterior longitudinal ligament and attaching to the deep layer of the posterior longitudinal ligament. It has been given relatively little attention in the past. This membrane has about one fourth the toughness of the dura and is made up largely of fibrous tissue. The veins of Batson lie on its dorsal surface and pierce it to go ventral to this membrane and enter the vertebral body. Batson's plexus crosses the disc space. The peridural membrane extends from one side to the other, spanning the width of the vertebral body and encircling the bony canal around the outside of the dura. There is a potential space between it and the dura. It does not cross the disc space. A probe can easily be passed posterior or anterior to it, between it and the posterior longitudinal ligament or between it and the vertebral body. We also identified Hofmann's ligament anterior to the dura, attaching the dura to the posterior longitudinal ligament. Laterally, tiny attachments between this fibrovascular membrane and the circumneural sheaths of the spinal nerves can be observed as the nerves enter the foramina. The posterior longitudinal ligament (PLL) is very tough and strong and seldom ruptures. The annulus frequently ruptures. Fragments of nucleus pulposus can creep out at the vertebral rim and get under the PLL and the peridural membrane. Hematoma can form by the same route and have the exact appearance as a sequestrated disc. There is no periosteum inside the vertebral canal. With MRI, hematomas can be differentiated from an extruded fragment. They may cause symptoms similar to an extruded disc but will probably heal with time.(ABSTRACT TRUNCATED AT 400 WORDS)
Computed tomography is a commonly used technique for detecting pathological alterations in soft tissues and the skeleton. Three-dimensional images of the skeleton are very useful for planning surgical treatment and monitoring therapy, but unfortunately mental reconstruction of complex three-dimensional anatomical structures from conventional tomography is very difficult. This article describes a process by which automated analysis of the regions of interest in the computed tomographic (CT) images yields the contours of the surfaces which can be presented pseudo-three-dimensionally using Phong's lighting model and Gouraud's shading methods. Three applications in the areas of orthopedics and neurosurgery demonstrate the efficacy of the method.
A patient with Wegener granulomatosis presented with diffuse tracheal narrowing and was evaluated using CT and cine-CT. The CT findings included severe laryngeal and tracheal airway narrowing, due to abnormal soft tissue within the laryngeal cartilages and tracheal rings, and enlarged abnormally calcified tracheal cartilages. Computed tomography precisely confirmed the site, level, and submucosal extent of tracheal narrowing, not obtainable on physical or bronchoscopic examination, and assisted in choosing a site for tracheostomy. Wegener granulomatosis should be considered in patients with diffuse tracheal narrowing even when the typical histology is not present.
Given the geometric complexity of anatomical structures, realistic real-time deformation of graphical reconstructions is prohibitively computationally intensive. Instead, real-time deformation of virtual anatomy is roughly approximated through simpler methodologies. Since the graphical interpolations and simple spring models commonly used in these simulations are not based on the biomechanical properties of tissue structures, these "quick and dirty" methods typically do not accurately represent the complex deformations and force-feedback interactions that can take place during surgery. Finite element (FE) analysis is widely regarded as the most appropriate alternative to these methods. Extensive research has been directed toward applying the method to modeling a wide range of biological structures, and a few simple FE models have been incorporated into surgical simulations. However, because of the highly computational nature of the FE method, its direct application to real-time force-feedback and visualization of tissue deformation has not been practical for most simulations. This limitation is primarily due to the overabundance of information provided by the standard FE approaches. If the mathematics is optimized to yield only the information essential for the surgical task, computation time can be drastically reduced. Parallel computation and preprocessing of the model before the simulation begins can also reduce the size of the problem and greatly increase computation speed. Such methodologies are being developed in a combined effort between the Human Interface Technology Laboratory (HIT Lab) and the Mechanical Engineering Department of the University of Washington. We have created computer demonstrations which support real-time interaction with simple finite element soft tissue models. In collaboration with the Division of Dermatology, a real-time skin surgery simulator is being developed using these fast FE methods.
Posttraumatic enophthalmos is one of the common sequelae that appears after facial injury and remains a challenge to treat for craniomaxillofacial surgeons. Several theories have been advocated regarding enophthalmos; however, the most well accepted concept is the enlargement of the orbital cavity after displacement due to orbital fractures. Generally, a 1 cm3 increase in orbital volume causes 0.8 mm of enophthalmos. Thorough knowledge of the orbital anatomy is fundamental and critical for the successful surgical correction of enophthalmos because most treatment failures are due to inadequate orbital dissection from fear of injuring the optic nerve and globe. A complete preoperative plan should be built on a comprehensive clinical examination of the periorbital soft tissue and bony components, detailed ophthalmic examination, and high resolution computed tomography scans in the axial, coronal and reformatted sagittal planes. Based on the anatomic deformities, there are two major fracture types including orbital blow out fractures and zygomatico-orbital fractures, resulting in posttraumatic enophthalmos. Treatment modalities and methods of approach are adapted according to the severity of the orbital deformities. Minor complications include ectropion, entropion, dystopia, diplopia, and residual enophthalmos. Rare but severe complications such as intraconal misplacement of the bone graft or retrobulbar hemorrhage with subsequent blindness may be encountered. The success of the procedures depend on adequate dissection and mobilization of the displaced soft tissue, correct repositioning of the dislocated or malunited bony orbit, and proper intra-orbital grafting.