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PubMed1998

Simultaneous transfer of free fibula and radial forearm flaps for complex oromandibular reconstruction.

Several composite free flaps have been described for use in oromandibular reconstruction. Particularly in extensive defects, there may be no single flap which combines sufficient bone stock with thin, pliable, soft tissue. By combining two free flaps, the best osseous and soft-tissue elements may be independently selected, to yield a result superior to that achievable with one free flap alone. Thirteen patients underwent reconstruction of extensive oromandibular defects using the free fibula for mandibular reconstruction and the free radial forearm flap for oral lining and soft-tissue reconstruction. Mandibular defects were usually extensive, involving over half of the mandibular contour. Soft-tissue defects were all complex and involved multiple surfaces of the oral, oropharyngeal, and nasopharyngeal mucosa. All patients were operated on in the supine position by two surgical teams (extirpative and reconstructive) working simultaneously. Each free flap was supplied by its own set of recipient vessels. The mean total operating time was 12 hr. Postoperative courses were without mortality or significant morbidity. There were no flap failures. Soft-tissue and osseous reconstructions healed completely. Aesthetic contour was judged good to excellent in 11 patients. Soft and solid diets were achieved in five patients, with six patients on a purée or liquid diet. Oral competence was present in 11 patients. Speech was excellent to good in six patients and fair in four patients. The mean follow-up has averaged 18 months. Three patients have died of recurrent disease, and two of unrelated causes. The remaining eight patients are currently free of disease. In combining the free flaps, the best tissue for bone and soft-tissue reconstruction was selected independently. The two-team approach avoided excessive operating time and operating team fatigue. The added degree of freedom provided by the two free flaps with their independent pedicles made insetting easier, compared to working within the limitations of a single composite flap. For extensive oromandibular defects, the simultaneous free fibula and radial forearm free flaps provided ideal osseous and soft-tissue reconstruction, with acceptable operating times and reasonable functional results.

Adult↗

PubMed1998

Second free flaps in head and neck reconstruction.

Over the past decade, free-tissue transfer has greatly improved the quality of oncology-related head and neck reconstruction. As this technique has developed, second free flaps have been performed for aesthetic improvement of the reconstructed site. This study evaluated the indications for and the success of second free flaps. Medical files for patients who underwent second free flaps for head and neck reconstruction at the University of Texas M.D. Anderson Cancer Center, from May 1, 1988 to November 30, 1996, were reviewed. The flaps were classified as being either immediate (done within 72 hr) or delayed (done within 2 years) reconstructions. Indications, risk factors, recipient vessels, outcome, and complications were analyzed. Of the 28 patients included in this study, 12 had immediate (nine as salvage after primary free flap failure, and three for reconstruction of a soft-tissue defect), and 16 had delayed second free flaps (two for reconstruction of a defect resulting from excision of recurrent tumors, and 14 for aesthetic improvement). Reconstruction sites included the oral cavity in 18 patients; the midface in six; the skull base in two; and the scalp in two. The success rate for the second free flaps was 96 percent. Five patients had significant wound complications. In a substantial number of cases, identical recipient vessels were used for both the first and second free flaps. The authors conclude that second free flaps can play an important role in salvaging or improving head and neck reconstruction in selected patients. In many cases, the same recipient vessels can be used for both the first and second flaps.

Adolescent↗

PubMed2005

Psychoanalytic reconstruction and reintegration.

Psychoanalytic reconstruction has declined in theoretical and clinical interest as greater attention has been directed to the here and now of the transference-counter-transference field and inter-subjectivity. Transference, however, is based upon childhood fantasy, and is a new edition of unconscious intra-psychic representation and relationships. In this paper transference is viewed as a guide to reconstruction, but transference itself is also an object of reconstruction. Reconstruction is a complementary agent of change, which integrates genetic interpretations and restores the continuity of the self The patient's childish traits, features, fixations, and irrational childish fantasies and behavior point to the necessity for reconstruction. Reconstruction organizes dissociated, fragmented memories, potentiating the further retrieval of repressed memories. Reconstruction is essential to the working through and attenuation of early traumatic experience. Recapture of the past is necessary to demonstrate and diminish the persistent influence of the past in the present, and to meaningfully connect past and present. A case is presented in which reconstruction had a central, vital role in the analytic process.

Adaptation, Psychological↗

PubMed2006

Comfort, control, or conformity: women who choose breast reconstruction following mastectomy.

Following breast amputation women commonly are presented with two choices: to wear a prosthesis or undergo reconstruction. Breast restoration is assumed to allow a full emotional and physical recovery from a breast cancer crisis. Surgical reconstruction is offered to women as the final step in regaining a sense of complete womanhood, enabling a sense of optimism that both body and self will "get back to normal." This article examines 5 women's accounts of breast reconstruction and asks how breast reconstruction figures in the remaking of self following mastectomy. Issues pertaining to the reasoning behind seeking out the procedure, experiences of finding the right surgeon, and how women feel toward their reconstructed postsurgical body are examined. In conclusion it is argued that a number of contradictory expectations are held by women seeking reconstructions. While women suggest that reconstruction will restore lost femininity, sexuality, and normalcy in most cases it is not the procedure that enables this but the elimination of the hassles of prostheses. In contrast to the complete sense of self they expected to regain through reconstruction they articulate a restoration that is simply pragmatic. It is only once women have undertaken this last bastion of hope that they are forced to renegotiate their sense of themselves as women with or without breasts.

Adaptation, Psychological↗

PubMed2000

Tomographic reconstruction of tracer gas concentration profiles in a room with the use of a single OP-FTIR and two iterative algorithms: ART and PWLS.

Computed tomographic (CT) reconstructions of air contaminant concentration fields were conducted in a room-sized chamber employing a single open-path Fourier transform infrared (OP-FTIR) instrument and a combination of 52 flat mirrors and 4 retroreflectors. A total of 56 beam path data were repeatedly collected for around 1 hr while maintaining a stable concentration gradient. The plane of the room was divided into 195 pixels (13 x 15) for reconstruction. The algebraic reconstruction technique (ART) failed to reconstruct the original concentration gradient patterns for most cases. These poor results were caused by the "highly underdetermined condition" in which the number of unknown values (156 pixels) exceeds that of known data (56 path integral concentrations) in the experimental setting. A new CT algorithm, called the penalized weighted least-squares (PWLS), was applied to remedy this condition. The peak locations were correctly positioned in the PWLS-CT reconstructions. A notable feature of the PWLS-CT reconstructions was a significant reduction of highly irregular noise peaks found in the ART-CT reconstructions. However, the peak heights were slightly reduced in the PWLS-CT reconstructions due to the nature of the PWLS algorithm. PWLS could converge on the original concentration gradient even when a fairly high error was embedded into some experimentally measured path integral concentrations. It was also found in the simulation tests that the PWLS algorithm was very robust with respect to random errors in the path integral concentrations. This beam geometry and the use of a single OP-FTIR scanning system, in combination with the PWLS algorithm, is a system applicable to both environmental and industrial settings.

Air Pollution, Indoor↗

PubMed2006

Ancestral state reconstruction of body size in the Caniformia (Carnivora, Mammalia): the effects of incorporating data from the fossil record.

A recent molecular phylogeny of the mammalian order Carnivora implied large body size as the ancestral condition for the caniform subclade Arctoidea using the distribution of species mean body sizes among living taxa. "Extant taxa-only" approaches such as these discount character state observations for fossil members of living clades and completely ignore data from extinct lineages. To more rigorously reconstruct body sizes of ancestral forms within the Caniformia, body size and first appearance data were collected for 149 extant and 367 extinct taxa. Body sizes were reconstructed for four ancestral nodes using weighted squared-change parsimony on log-transformed body mass data. Reconstructions based on extant taxa alone favored large body sizes (on the order of 10 to 50 kg) for the last common ancestors of both the Caniformia and Arctoidea. In contrast, reconstructions incorporating fossil data support small body sizes (< 5 kg) for the ancestors of those clades. When the temporal information associated with fossil data was discarded, body size reconstructions became ambiguous, demonstrating that incorporating both character state and temporal information from fossil taxa unambiguously supports a small ancestral body size, thereby falsifying hypotheses derived from extant taxa alone. Body size reconstructions for Caniformia, Arctoidea, and Musteloidea were not sensitive to potential errors introduced by uncertainty in the position of extinct lineages relative to the molecular topology, or to missing body size data for extinct members of an entire major clade (the aquatic Pinnipedia). Incorporating character state observations and temporal information from the fossil record into hypothesis testing has a significant impact on the ability to reconstruct ancestral characters and constrains the range of potential hypotheses of character evolution. Fossil data here provide the evidence to reliably document trends of both increasing and decreasing body size in several caniform clades. More generally, including fossils in such analyses incorporates evidence of directional trends, thereby yielding more reliable ancestral character state reconstructions.

Animals↗

PubMed1994

Iterative concurrent reconstruction algorithms for emission computed tomography.

Direct reconstruction techniques, such as those based on filtered backprojection, are typically used for emission computed tomography (ECT), even though it has been argued that iterative reconstruction methods may produce better clinical images. The major disadvantage of iterative reconstruction algorithms, and a significant reason for their lack of clinical acceptance, is their computational burden. We outline a new class of 'concurrent' iterative reconstruction techniques for ECT in which the reconstruction process is reorganized such that a significant fraction of the computational processing occurs concurrently with the acquisition of ECT projection data. These new algorithms use the 10-30 min required for acquisition of a typical SPECT scan to iteratively process the available projection data, significantly reducing the requirements for post-acquisition processing. These algorithms are tested on SPECT projection data from a Hoffman brain phantom acquired with a 2 x 10(5) counts in 64 views each having 64 projections. The SPECT images are reconstructed as 64 x 64 tomograms, starting with six angular views. Other angular views are added to the reconstruction process sequentially, in a manner that reflects their availability for a typical acquisition protocol. The results suggest that if T s of concurrent processing are used, the reconstruction processing time required after completion of the data acquisition can be reduced by at least 1/3T s.

Algorithms↗

PubMed2003

Helical cardiac cone beam reconstruction using retrospective ECG gating.

In modern computer tomography (CT) systems, the fast rotating gantry and the increased detector width enable 3D imaging of the heart. Cardiac volume CT has a high potential for non-invasive coronary angiography with high spatial resolution and short scan time. Due to the increased detector width, true cone beam reconstruction methods are needed instead of adapted 2D reconstruction schemes. In this paper, the extended cardiac reconstruction method is introduced. It integrates the idea of retrospectively gated cardiac reconstruction for helical data acquisition into a cone beam reconstruction framework. It leads to an efficient and flexible algorithmic scheme for the reconstruction of single- and multi-phase cardiac volume datasets. The method automatically adapts the number of cardiac cycles used for the reconstruction. The cone beam geometry is fully taken into account during the reconstruction process. Within this paper, results are presented on patient datasets which have been acquired using a 16-slice cone beam CT system.

Algorithms↗

PubMed2005

Exact fan-beam image reconstruction algorithm for truncated projection data acquired from an asymmetric half-size detector.

In this paper, we present a new algorithm designed for a specific data truncation problem in fan-beam CT. We consider a scanning configuration in which the fan-beam projection data are acquired from an asymmetrically positioned half-sized detector. Namely, the asymmetric detector only covers one half of the scanning field of view. Thus, the acquired fan-beam projection data are truncated at every view angle. If an explicit data rebinning process is not invoked, this data acquisition configuration will reek havoc on many known fan-beam image reconstruction schemes including the standard filtered backprojection (FBP) algorithm and the super-short-scan FBP reconstruction algorithms. However, we demonstrate that a recently developed fan-beam image reconstruction algorithm which reconstructs an image via filtering a backprojection image of differentiated projection data (FBPD) survives the above fan-beam data truncation problem. Namely, we may exactly reconstruct the whole image object using the truncated data acquired in a full scan mode (2pi angular range). We may also exactly reconstruct a small region of interest (ROI) using the truncated projection data acquired in a short-scan mode (less than 2pi angular range). The most important characteristic of the proposed reconstruction scheme is that an explicit data rebinning process is not introduced. Numerical simulations were conducted to validate the new reconstruction algorithm.

Algorithms↗

PubMed2006

Tilted cone-beam reconstruction with row-wise fan-to-parallel rebinning.

Reconstruction algorithms for cone-beam CT have been the focus of many studies. Several exact and approximate reconstruction algorithms were proposed for step-and-shoot and helical scanning trajectories to combat cone-beam related artefacts. In this paper, we present a new closed-form cone-beam reconstruction formula for tilted gantry data acquisition. Although several algorithms were proposed in the past to combat errors induced by the gantry tilt, none of the algorithms addresses the scenario in which the cone-beam geometry is first rebinned to a set of parallel beams prior to the filtered backprojection. We show that the image quality advantages of the rebinned parallel-beam reconstruction are significant, which makes the development of such an algorithm necessary. Because of the rebinning process, the reconstruction algorithm becomes more complex and the amount of iso-centre adjustment depends not only on the projection and tilt angles, but also on the reconstructed pixel location. In this paper, we first demonstrate the advantages of the row-wise fan-to-parallel rebinning and derive a closed-form solution for the reconstruction algorithm for the step-and-shoot and constant-pitch helical scans. The proposed algorithm requires the 'warping' of the reconstruction matrix on a view-by-view basis prior to the backprojection step. We further extend the algorithm to the variable-pitch helical scans in which the patient table travels at non-constant speeds. The algorithm was tested extensively on both the 16- and 64-slice CT scanners. The efficacy of the algorithm is clearly demonstrated by multiple experiments.

Algorithms↗

PubMed2006

Evaluation of accelerated iterative x-ray CT image reconstruction using floating point graphics hardware.

Statistical reconstruction methods offer possibilities to improve image quality as compared with analytical methods, but current reconstruction times prohibit routine application in clinical and micro-CT. In particular, for cone-beam x-ray CT, the use of graphics hardware has been proposed to accelerate the forward and back-projection operations, in order to reduce reconstruction times. In the past, wide application of this texture hardware mapping approach was hampered owing to limited intrinsic accuracy. Recently, however, floating point precision has become available in the latest generation commodity graphics cards. In this paper, we utilize this feature to construct a graphics hardware accelerated version of the ordered subset convex reconstruction algorithm. The aims of this paper are (i) to study the impact of using graphics hardware acceleration for statistical reconstruction on the reconstructed image accuracy and (ii) to measure the speed increase one can obtain by using graphics hardware acceleration. We compare the unaccelerated algorithm with the graphics hardware accelerated version, and for the latter we consider two different interpolation techniques. A simulation study of a micro-CT scanner with a mathematical phantom shows that at almost preserved reconstructed image accuracy, speed-ups of a factor 40 to 222 can be achieved, compared with the unaccelerated algorithm, and depending on the phantom and detector sizes. Reconstruction from physical phantom data reconfirms the usability of the accelerated algorithm for practical cases.

Algorithms↗

PubMed2006

Direct reconstruction of tissue parameters from differential multifrequency EIT in vivo.

The basic purpose of electrical impedance tomography (EIT) is the reconstruction of conductivity distributions. While multifrequency measurements are of common use, the majority of reconstructed images are still conductivity distributions from one single frequency. More interesting than conductivities at each frequency are electrical tissue parameters, which describe the frequency-dependent conductivity changes of tissue. These parameters give information about physiological or electrical properties of tissues. By using this spectral information, a classification of different tissue types is possible. To get a distribution of tissue parameters, usually a posterior fitting of a tissue model to the conductivity spectra obtained with classical reconstruction algorithms at various frequencies is used. In this work, a single-step reconstruction algorithm for differential imaging was developed for the direct estimation of Cole parameters. This method is termed differential parametric reconstruction. The Cole model was used as the underlying tissue model, where only the relative changes of the two conductivity parameters sigma(0) and sigma(infinity) were reconstructed and the other two parameters of the model which are less identifiable were set to constant values. The reconstruction algorithm was tested with simulated noisy datasets and real measurement data from EIT measurements on the human thorax. These measurements were taken from healthy subjects and from patients with a serious lung injury. The new method yields a good image quality and higher robustness against noise compared to conventional reconstruction methods.

Algorithms↗

PubMed1984

Breast reconstruction: a review.

Remarkable advances have been made in the field of breast reconstruction, especially since general surgeons, patients, and the community as a whole have become more knowledgeable and accepting. This has provided an impetus for plastic surgeons to develop better techniques, many of which are reviewed here. In general, less time now elapses between ablative and reconstructive surgery, and frequently reconstruction follows immediately. Procedures requiring fewer steps with less donor and recipient site morbidity are favored for both the mound and nipple areolar reconstruction. There is a definite trend toward submuscular implantation to minimize the negative effects of capsular contracture. With a deficiency of skin or muscle, the trend is toward using musculocutaneous flaps primarily, latissimus dorsi, and more recently the rectus abdominis flap. Occasionally, microvascular flap reconstruction is indicated for extensive chest wall defects, e.g., postirradiation injury. Reconstructed breasts are not capable of nourishment, frequently are not erogenous , and most often are not as pleasing to the eye as the contralateral breast. Yet reconstruction has, in the majority of cases, improved the quality of life for those women who have developed breast cancer and offered hope to those women in a high-risk category for developing breast cancer. To those ends, the search for the perfect breast reconstruction will continue.

Breast↗

PubMed1986

Breast reconstruction by tissue expansion for congenital and burn deformities.

We have used tissue expanders to treat 10 patients with breast deformities, 2 the result of burns and 8 congenital in origin. The expanders are placed in the subglandular plane and expanded incrementally until the desired amount of growth is obtained. In patients with congenital deformities, the desired size of the reconstructed breast (implant size) is determined during the expansion phase. Reconstructions of the nipple-areola complex are done either at the time of the exchange or as separate procedures. Patients with burn deformities present a variety of problems not seen with the congenital deformities. The expander is placed in the subglandular plane and filled to the desired volume. We have noted a marked permanent softening of the scar and grafts encasing the breast, which persists after the expander is removed and the breast reconstructed. The interval between expansion and definitive reconstruction is delayed for several months to allow scar softening to take place. If the parenchyma is not burned and pedicle tissue is not required, the expander can be deflated and the skin coverage observed to determine if it will remain soft. If it does, the expander can be removed and the breast reconstructed. In patients who require pedicle coverage in the reconstruction and who have unburned scar surrounding the breast, massive overexpansion is carried out. The pedicle skin is used to resurface the breast after removal of the appropriate areas of scar and skin grafts. In all burned patients, the inframammary fold must be reconstructed if the breast is to be protuberant. The nipple-areola complex also requires reconstruction. To date there has been great acceptance by patients with both congenital and burn deformities; however, we believe that tissue expansion techniques offer possibilities that have not as yet been fully explored.

Adolescent↗

PubMed1990

Secondary reconstruction of posttraumatic orbital deformities.

A retrospective analysis of our experience, techniques, and concepts for the secondary reconstruction of orbital injuries to 78 patients over a 15-year period is presented. Secondary orbital reconstruction has the following four basic steps: (1) freeing of the overlying soft tissues by extensive subperiosteal dissection; (2) skeletal reconstruction, usually with onlay bone grafting and contour osteoplasty; (3) restoration of palpebral shape and position by medial and lateral canthopexy; and (4) soft-tissue refinement. Reconstruction required an average of at least two operations. In this series, there were no mortalities, three infections, and no reoperations for bleeding. Thirty patients required a second operation to an area previously addressed reflecting inadequacies in technique, the unpredictability of bone grafts, and soft-tissue scarring. Distortion of the skeletal infrastructure is most amenable to secondary reconstruction. Soft-tissue distortions that accompany bone malposition are less well corrected. Soft-tissue contraction is the limiting factor in successful reconstruction dictating separate movement of the overlying soft tissues and ligaments, their overcorrection, and subsequent revisional surgery. Secondary orbital reconstruction, although providing significant improvement, usually fails to restore the preinjury appearance, and usually falls short of properly performed acute reconstruction.

Adolescent↗

PubMed1996

Microsurgical reconstruction of the head and neck: interdisciplinary collaboration between head and neck surgeons and plastic surgeons in 305 cases.

Three hundred five microsurgical free flaps have been performed for defects of the head and neck by a team of two head and neck surgeons and two plastic surgeons over a 9-year period, with a success rate of 91.2%. The most common flaps used were the jejunum (89), radial forearm (57), rectus abdominis (48), latissimus dorsi (40), scapular (32), fibula (15), and iliac crest (11). Thirty-three flaps required reexploration for anastomotic thrombosis or hematoma (10.8%), of which 18 flaps were salvaged (54.5%). Thirteen flap failures occurred in 113 patients who had received preoperative irradiation (11.5%), but this was not statistically significant. Seven flaps failed in 20 patients who required an interposition vein graft (35%) and this was statistically significant. Ninety patients (31.5%) developed a major complication other than anastomotic thrombosis or death. Despite postoperative intensive care nursing and monitoring, 18 patients died postoperatively in the hospital (6.3%). The average hospital stay was 21.1 days with a range from 5 to 95 days. During this 9-year time period, various free flaps have evolved as the preferred choice for free flap reconstruction of a specific defect of the head and neck. The latissimus dorsal muscle flap surfaced with a nonmeshed split-thickness skin graft is the optimal free flap for reconstruction of the scalp and skull, whereas a multiple-paddle latissimus dorsi musculocutaneous flap is the best flap for reconstruction of complex defects of the middle third of the face and maxilla. The radial forearm flap and free jejunal transfer have become the preferred choices for intraoral reconstruction and pharyngo-esophageal reconstruction, respectively. There still remains no universally accepted flap for mandibular reconstruction, but the fibular osteocutaneous flap and a reconstruction plate protected by a radial forearm flap have largely superseded the iliac crest and scapular osteocutaneous flaps. Radical resection of tumors of the head and neck with immediate reconstruction by microsurgical free tissue transfer followed by adjuvant radiation therapy provides the best possible chance for cure and functional and social rehabilitation of the patient.

Adolescent↗

PubMed1997

Median sternotomy wound complication: the effect of reconstruction on lung function.

The objective of the study was to evaluate the lung function of patients with median sternotomy wound complication during the early postmedian sternotomy period and to compare the long-term pulmonary effects of reconstruction using pectoralis major and rectus abdominis muscle flaps. The percentage of predicted, standardized forced vital capacity (FVC); the standardized forced expiratory volume in 1 second (FEV1), and FEV1/FVC ratios of 45 patients with a median sternotomy wound complication were evaluated before and at a mean time of 10.6 months after wound reconstruction. Both mean FVC and FEV1 increased after wound revision compared with the prereconstruction results (8.4% and 9.2% increase, respectively). Patients with painful chest wall movement had the worst (60%) mean FVC and FEV1 before reconstruction when compared with a nonpainful complication. Reconstruction with a muscle flap was followed by an increase of 8.6% and 7.3% in FEV1 and FVC, respectively, from prereconstruction results. However, long-term results indicate that these patients have a mild, restrictive impairment of their lung function tests (LFTs), with about 80% of the predicted FVC and FEV1. Among the muscle flaps, the best improvement and best long-term LFT results were after sternectomy and reconstruction with a pectoralis major muscle flap as compared with a rectus abdominis muscle flap. Sternectomy and reconstruction with a muscle flap is a well-tolerated procedure associated with improvement of lung function compared with prereconstruction values. A pectoralis major muscle flap should be the first choice for muscle flap reconstruction while a rectus abdominis muscle flap should be reserved only for patients with good LFTs before reconstruction.

Adult↗

PubMed1998

Versatility of the microvascular serratus anterior muscle vascularized rib flap (SARIB) for multifaceted requirement reconstructions.

We have employed the serratus anterior muscle vascularized rib (SARIB) composite flap for a variety of multifaceted reconstructive applications in which bone and soft tissues were needed. Seventeen patients have undergone this procedure for reconstructions of the upper extremity (5), lower extremity reconstructions (4), and reconstruction of head and neck defects (8). Sixteen of the reconstructions (89%) have been successful, with an average follow-up over 2 years. One patient had partial loss of a rib transferred to the head and neck for palatal reconstruction. One patient had complete flap loss of a maxillectomy reconstruction owing to a necrotizing infection. We have found this procedure to be applicable to a number of clinical reconstructive situations and recommend the SARIB procedure as a versatile operation that is successful in a high percentage of cases.

Female↗