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PubMed2003

Optimizing autologous breast reconstruction in thin patients.

Breast reconstruction with a transverse rectus abdominis myocutaneous (TRAM) flap plus an implant has been proposed as an option for women with a thin body habitus who do not have sufficient abdominal tissue to permit reconstruction with a TRAM flap alone. The standard autologous tissue reconstructive procedure in these women is a combined latissimus dorsi myocutaneous flap and breast implant. We reviewed our experience performing TRAM flap/implant and latissimus dorsi flap/implant breast reconstruction to compare complication rates and aesthetic outcomes between these two types of reconstruction. Between 1992 and 1999, 88 breasts were reconstructed at our institution using an autologous tissue flap combined with a breast implant (44 with a TRAM flap/implant and 44 with a latissimus dorsi flap/implant). Recipient-site and donor-site complications for the two procedures were compared using Fisher's exact test; a panel of unbiased, blinded judges compared the aesthetic outcomes. The recipient-site complication rate was lower for the TRAM flap/implant group than for the latissimus dorsi flap/implant group (18 percent versus 34 percent, p = 0.09). Most recipient-site complications in the TRAM flap/implant group were related to fluid collection around the implant. In the TRAM flap/implant group, complications occurred in 37 percent of the reconstructions that had immediate implant placement and in none of the reconstructions with delayed implant placement (p = 0.01). In the TRAM flap/implant reconstructions with immediate implant placement, the recipient-site complication rate was 50 percent when implants were completely filled with saline, but no complications occurred with incompletely filled, postoperatively adjustable implants (p = 0.03). No microvascular complications occurred with immediate placement of breast implants under TRAM flaps. Donor-site complications included a hematoma, a seroma, and an umbilical necrosis in the TRAM flap/implant group and six cases of seroma formation in the latissimus dorsi flap/implant group. The comparison of aesthetic outcome was statistically significant for the TRAM flap/implant group, which had a higher overall mean score than the latissimus dorsi flap/implant group did (3.29 versus 2.85, p = 0.01). The results of this study suggest that the TRAM flap/implant breast reconstruction should be considered as an alternative to the latissimus dorsi flap/implant breast reconstruction in women with a thin body habitus.

Adult↗

PubMed2004

Breast reconstruction with superficial inferior epigastric artery flaps: a prospective comparison with TRAM and DIEP flaps.

Breast reconstruction using the lower abdominal free superficial inferior epigastric artery (SIEA) flap has the potential to virtually eliminate abdominal donor-site morbidity because the rectus abdominis fascia and muscle are not incised or excised. However, despite its advantages, the free SIEA flap for breast reconstruction is rarely used. A prospective study was conducted of the reliability and outcomes of the use of SIEA flaps for breast reconstruction compared with transverse rectus abdominis musculocutaneous (TRAM) and deep inferior epigastric perforator (DIEP) flaps. Breast reconstruction with an SIEA flap was attempted in 47 consecutive free autologous tissue breast reconstructions between August of 2001 and November of 2002. The average patient age was 49 years, and the average body mass index was 27 kg/m. The SIEA flap was used in 14 (30 percent) of these breast reconstructions in 12 patients. An SIEA flap was not used in the remaining 33 cases because the SIEA was absent or was deemed too small. The mean superficial inferior epigastric vessel pedicle length was approximately 7 cm. The internal mammary vessels were used as recipients in all SIEA flap cases so that the flap could be positioned sufficiently medially on the chest wall. The average hospital stay was significantly shorter for patients who underwent unilateral breast reconstruction with SIEA flaps than it was for those who underwent reconstruction with TRAM or DIEP flaps. Of the 47 free flaps, one SIEA flap was lost because of arterial thrombosis. Medium-size and large breasts were reconstructed with hemi-lower abdominal SIEA flaps, with aesthetic results similar to those obtained with TRAM and DIEP flaps. The free SIEA flap is an attractive option for autologous tissue breast reconstruction. Harvest of this flap does not injure the anterior rectus fascia or underlying rectus abdominis muscle. This can potentially eliminate abdominal donor-site complications such as bulge and hernia formation, and decrease weakness, discomfort, and hospital stay compared with TRAM and DIEP flaps. The disadvantages of an SIEA flap are a smaller pedicle diameter and shorter pedicle length than TRAM and DIEP flaps and the absence or inadequacy of an arterial pedicle in most patients. Nevertheless, in selected patients, the SIEA flap offers advantages over the TRAM and DIEP flaps for breast reconstruction.

Epigastric Arteries↗

PubMed2005

Reconstruction of acquired scalp defects: an algorithmic approach.

LEARNING OBJECTIVES: After studying this article, the participant should: 1. Understand scalp anatomy, hair physiology, and skin viscoelastic properties as they relate to scalp reconstruction. 2. Understand the principles that allow for aesthetic reconstruction of scalp defects. 3. Understand the use of local tissue rearrangement for reconstruction of specific areas of the scalp. 4. Understand the use of tissue expansion and free tissue transfer for scalp reconstruction. BACKGROUND: Reconstruction of scalp defects is required for acute trauma, tumor extirpation, radiation necrosis, and the repair of traumatic alopecia or cosmetically displeasing scars. METHODS: The proper choice of a reconstructive technique is affected by several factors-the size and location of the defect, the presence or absence of periosteum, the quality of surrounding scalp tissue, the presence or absence of hair, location of the hairline, and patient comorbidities. Successful reconstruction of these defects requires a detailed knowledge of scalp anatomy, hair physiology, skin biomechanics, and the variety of possible local tissue rearrangements. In nearly total defects, local tissues may be inadequate and tissue expansion or free tissue transfer may be the only alternatives. RESULTS: Plastic surgeons are now able to obtain coverage over the calvaria after the most devastating of defects; however, the challenge to the reconstructive surgeon today is to do so with excellent cosmetic results. Cosmetic scalp reconstruction requires restoration and preservation of normal hair patterns and hair lines. CONCLUSIONS: Successful reconstruction of the scalp requires careful preoperative planning and precise intraoperative execution. Detailed knowledge of scalp anatomy, skin biomechanics, hair physiology, and the variety of available local tissue rearrangements allows for excellent aesthetic reconstruction.

Algorithms↗

PubMed2006

Breast reconstruction in older women: should age be an exclusion criterion?

BACKGROUND: At present, breast reconstruction is undertaken by fewer than 10 percent of breast cancer patients undergoing mastectomy. Even though the benefits are numerous, this finding is even more notable among older women. Traditionally, women older than the age of 60 have been offered implant reconstruction or no reconstruction at all in hopes of minimizing potential morbidity. This practice may be due to a number of factors including a lack of patient education and information, as well as physician/surgeon bias regarding the safety or relevance of breast reconstruction in older women. METHODS: The authors undertook a retrospective study in which they surveyed 75 women (age range, 60 to 77 years) from two surgeons' practices who underwent various forms of breast reconstruction over the past 8 years. Type of reconstruction, recovery time, and complication rate were correlated with patient satisfaction, general health, and quality of life. RESULTS: An 81 percent response rate was obtained, yielding an average age of 66.6 years over a 3.8-year period. The overall rate of complications requiring operative intervention was 20.5 percent. When asked whether age should be a determining factor for breast reconstruction, more than 90 percent felt that it should not be. Only 16.1 percent of patients who had a delayed reconstruction stated that the option of breast reconstruction was presented to them at the time of their diagnosis, although 100 percent felt that it should have been. A significantly poorer physical health score was found among patients who experienced a complication, and lower mental health scores correlated with women who were less satisfied with their outcome. CONCLUSIONS: The authors believe that all types of reconstruction should be an option for women older than 60 years of age and that age as an isolated factor should not deter physicians from offering these women the option of breast reconstruction.

Aged↗

PubMed2003

Breast reconstruction in the elderly: preserving excellent quality of life.

There is a paucity of information in the literature that focuses on quality-of-life issues after mastectomy with breast reconstruction in elderly women. The purpose of this study was to review the authors' experience with breast reconstruction after mastectomy in women older than 65 years of age. Emphasis was placed on the types of reconstructions, outcomes, and evaluation of issues related to quality of life. Between July 1997 and July 2001, 316 consecutive women (400 reconstructions) with breast cancer underwent mastectomy with reconstruction at the authors' institution. Of these women, 24 (28 reconstructions) were at least 65 years old. Mean patient age was 69.3 years (range, 65-77 years). Methods of breast reconstruction included two-stage implant reconstruction (50%), free tissue transfer (transverse rectus abdominis musculocutaneous or deep inferior epigastric perforator flap, 25%), pedicle transverse rectus abdominis musculocutaneous flap (14%), or a latissimus dorsi musculocutaneous flap (11%). Outcomes were assessed with the use of a self-reported questionnaire (SF-36) addressing health-related quality of life, body image, and physical functioning. With respect to overall quality-of-life issues after reconstruction, older patients with breast reconstruction scored higher (better outcomes) than age-matched general population patients and previously reported mastectomy-only patients (>55 years) in all surveyed areas. Specifically, study patients reported dramatic increases (better outcomes) in the subscales that are strongly influenced by one's mental health. However, when compared with prior data for younger patients undergoing mastectomy and reconstruction, the older patients scored lower (worse outcomes) in the areas related to physical function. The older patients maintained superior scores (better outcomes) over the younger patients in the subscales influenced by one's mental health.

Adult↗

PubMed2004

Further experience with innervated autologous flaps in postoncologic breast reconstruction.

Restoration of sensation remains an area of minimal concern in autologous breast reconstruction. In contrast, it is routine for the reconstructive surgeon to include sensory restoration as part of the reconstruction of the upper and lower limb and the head and neck. We have utilized sensate autologous soft tissue units for breast reconstruction and present the results of a four-year period. Among a cohort of 15 women who underwent sensate breast reconstruction improvement in all sensory modalities tested, both rapidity of sensory return and strength of sensation were noted when compared to reported sensory outcomes among women undergoing non-sensate breast reconstruction. Final sensory levels approached but did not equal the non-reconstructed contralateral breast. Operative times and wound healing complications were not statistically increased in sensate reconstructions as compared to a group on non-sensate reconstructions. The results of the study suggest that sensate reconstruction is a reasonable addition to autologous breast reconstruction.

Aged↗

PubMed2006

A multi-institutional analysis of the socioeconomic determinants of breast reconstruction: a study of the National Comprehensive Cancer Network.

OBJECTIVE: To determine the rate of postmastectomy reconstruction and investigate the impact of socioeconomic status on the receipt of reconstruction. SUMMARY BACKGROUND DATA: The National Comprehensive Cancer Network (NCCN) Outcomes Project is a prospective, multi-institutional database that contains data on all newly diagnosed breast cancer patients treated at one of the participating comprehensive cancer centers. METHODS: The study cohort consisted of 2174 patients with DCIS and stage I, II, and III invasive breast cancer who underwent mastectomy at one of 8 NCCN centers. Rates of reconstruction were determined. Logistic regression analyses were used to evaluate whether socioeconomic characteristics are associated with breast reconstruction. RESULTS: Overall, 42% of patients had breast reconstruction following mastectomy. Patients with Medicaid and Medicare were less likely to undergo reconstruction than those with managed care insurance; however, there was no difference for indemnity versus managed care insurance. Homemakers and retired patients had fewer reconstructions than those employed outside the home. Patients with a high school education or less were less likely to have reconstruction than those with more education. Race and ethnicity were not significant predictors of reconstruction. CONCLUSIONS: The reconstruction rate in this study (42%) is markedly higher than those previously reported. The type of insurance, education level, and employment status of a patient, but not her race or ethnicity, appear to influence the use of breast reconstruction. Because all patients were treated at an NCCN institution, these socioeconomic differences cannot be explained by access to care.

Adult↗

PubMed2006

New trends in breast cancer management: is the era of immediate breast reconstruction changing?

OBJECTIVE: Review of available literature on the topic of breast reconstruction and radiation is presented. Factors influencing the decision-making process in breast reconstruction are analyzed. New trends of immediate breast reconstruction are presented. SUMMARY BACKGROUND DATA: New indications for postmastectomy radiation have caused a dramatic increase in the number of radiated patients presenting for breast reconstruction. The major studies and their impact on breast cancer management practice are analyzed. Unsatisfactory results of conventional immediate reconstruction techniques followed by radiotherapy led to a new treatment algorithm for these patients. If the need for postoperative radiation therapy is known, a delayed reconstruction should be considered. When an immediate reconstruction is still desired despite the certainty of postoperative radiotherapy, reconstructive options should be based on tissue characteristics and blood supply. Autologous tissue reconstruction options should be given a priority in an order reflecting superiority of vascularity and resistance to radiation: latissimus dorsi flap, free TRAM or pedicled TRAM without any contralateral components of tissue, pedicled TRAM/midabdominal TRAM, and perforator flap. CONCLUSIONS: When the indications for postoperative radiotherapy are unknown, premastectomy sentinel node biopsy, delayed-immediate reconstruction, or delayed reconstruction is preferable.

Breast Neoplasms↗

PubMed2000

Improved image quality and computation reduction in 4-D reconstruction of cardiac-gated SPECT images.

Spatiotemporal reconstruction of cardiac-gated SPECT images permits us to obtain valuable information related to cardiac function. However, the task of reconstructing this four-dimensional (4-D) data set is computation intensive. Typically, these studies are reconstructed frame-by-frame: a nonoptimal approach because temporal correlations in the signal are not accounted for. In this work, we show that the compression and signal decorrelation properties of the Karhunen-Loève (KL) transform may be used to greatly simplify the spatiotemporal reconstruction problem. The gated projections are first KL transformed in the temporal direction. This results in a sequence of KL-transformed projection images for which the signal components are uncorrelated along the time axis. As a result, the 4-D reconstruction task is simplified to a series of three-dimensional (3-D) reconstructions in the KL domain. The reconstructed KL components are subsequently inverse KL transformed to obtain the entire spatiotemporal reconstruction set. Our simulation and clinical results indicate that KL processing provides image sequences that are less noisy than are conventional frame-by-frame reconstructions. Additionally, by discarding high-order KL components that are dominated by noise, we can achieve savings in computation time because fewer reconstructions are needed in comparison to conventional frame-by-frame reconstructions.

Algorithms↗

PubMed2000

2.5-D simultaneous multislice reconstruction by series expansion methods from Fourier-rebinned PET data.

True three-dimensional (3-D) volume reconstruction from fully 3-D data in positron emission tomography (PET) has only a limited clinical use because of its large computational burden. Fourier rebinning (FORE) of the fully 3-D data into a set of 2-D sinogram data decomposes the 3-D reconstruction process into multiple 2-D reconstructions of decoupled 2-D image slices, thus substantially decreasing the computational burden even in the case when the 2-D reconstructions are performed by an iterative reconstruction algorithm. On the other hand, the approximations involved in the rebinning combined with the decoupling of the image slices cause a certain reduction of image quality, especially when the signal-to-noise ratio of the data is low. We propose a 2.5-D Simultaneous Multislice Reconstruction approach, based on the series expansion principle, where the volume is represented by the superposition of 3-D spherically symmetric bell-shaped basis functions. It takes advantage of the time reduction due to the use of the FORE (2-D) data, instead of the original fully 3-D data, but at the same time uses a 3-D iterative reconstruction approach with 3-D basis functions. The same general approach can be applied to any reconstruction algorithm belonging to the class of series expansion methods (iterative or noniterative) using 3-D basis functions that span multiple slices, and can be used for any multislice sinogram or list mode data whether obtained by a special rebinning scheme or acquired directly by a PET scanner in the 2-D mode using septa. Our studies confirm that the proposed 2.5-D approach provides a considerable improvement in reconstruction quality, as compared to the standard 2-D reconstruction approach, while the reconstruction time is of the same order as that of the 2-D approach and is clinically practical even on a general-purpose computer.

Algorithms↗

PubMed2006

Reconstructions of shear modulus, Poisson's ratio, and density using approximate mean normal stress lambda epsilon alpha alpha as unknown.

As a differential diagnosis technique for living soft tissues, we are developing ultrasonic-strain-measurement-based shear modulus reconstruction methods. Previously, we reported three-dimensional (3-D) and 2-D reconstruction methods utilizing a typical Poisson's ratio very close to 0.5 (nearly-incompressible). However, because a decrease in the accuracy of the reconstructed value was confirmed to be due to the difference between the original value and the set value, we proposed 3-D and 2-D methods of reconstructing Poisson's ratio as well. Furthermore, we proposed methods of reconstructing density and dealing with dynamic deformation. However, due to tissue incompressibility, the reconstructions of shear modulus, Poisson's ratio, and density became unstable. In this report, to obtain stable, unique reconstructions, we describe a new reconstruction method using mean normal stress approximated by the product of one of Lame's constants X and volume strain epsilon alpha alpha as an unknown. Regularization is simultaneously applied to the respective distributions to decrease the instability of the reconstructions due to measurement errors of the deformation. This method also enables stable, unique reconstructions of shear modulus and density under the condition that the mean normal stress remains unknown. We also verify the effectiveness of this method through 3-D simulations, while showing erroneous artifacts occurring when 2-D and 1-D reconstructions are performed.

Algorithms↗

PubMed1995

Breast reconstruction using permanent tissue expanders.

The breast is a variable organ and as such reconstructive surgeons need to use a variety of reconstructive techniques. Prosthetic reconstruction is a good technique for women who are either unsuitable for or not accepting of autogenous tissue reconstruction. We reviewed the last five years' experience at Monash Medical Centre with permanent tissue expander breast reconstruction. Forty patients underwent reconstruction of 54 breasts. Immediate reconstruction was performed in 70% with an overall average patient age of 45 years. The selection criteria, advantages, and disadvantages of this technique are discussed. Inflation of expanders took an average of 71 days and creation of breast mound (excluding nipple/areolar reconstruction) took an average of 2.3 operations. Overall aesthetic results have been judged to be good to excellent in 81%. Symmetry was more easily achieved in bilateral reconstructions. Capsular contracture rate was Baker Grade I or II in 83%. Minor complications occurred in 17% of patients. We believe that there still exists a significant number of women who are either unsuitable for or not accepting of autogenous tissue reconstruction. It is this group of women who, if well selected, can be reconstructed safely and efficiently by the use of permanent tissue expander breast prosthesis.

Adult↗

PubMed2006

Region-of-interest reconstruction of motion-contaminated data using a weighted backprojection filtration algorithm.

The recently developed weighted backprojection filtration (WBPF) algorithm using data redundancy has capabilities that make this algorithm an attractive candidate for reconstructing images from motion-contaminated projection data. First, the WBPF algorithm is capable of reconstructing region-of-interest (ROI) images from reduced-scan fan-beam data, which have less data than the short-scan data required to reconstruct the entire field of view (FOV). Second, this algorithm can reconstruct ROI images from truncated data. Using phantom simulation studies, we demonstrate how these unique capabilities can be exploited to reduce the amount of motion-contaminated data used for reconstruction. In particular, we use examples from cardiac imaging to illustrate how off-center phantom positioning combined with phase-interval ROI reconstruction can result in the suppression of motion artifacts. In terms of temporal resolution, reduced-scan reconstruction with 45% of a full-scan dataset can be used to improve the temporal resolution of a short-scan reconstruction by 25.8% if ungated data are used. For data gated at 66 beats per minute, reduced-scan reconstruction with 45% of a full-scan dataset can be used to improve the temporal resolution of a short-scan reconstruction by 7.9%. As a result of our studies, we believe that the WBPF algorithm demonstrates the potential for reconstructing quality ROI images from motion-contaminated fan-beam data.

Algorithms↗

PubMed1999

Three-dimensional tongue surface reconstruction: practical considerations for ultrasound data.

This paper discusses methods for reconstructing the tongue from sparse data sets. Sixty ultrasound slices already have been used to reconstruct three-dimensional (3D) tongue surface shapes [Stone and Lundberg, J. Acoust. Soc. Am. 99, 3728-3737 (1996)]. To reconstruct 3D surfaces, particularly in motion, collecting 60 slices would be impractical, and possibly unnecessary. The goal of this study was to select a sparse set of slices that would best reconstruct the 18 measured speech sounds. First a coronal sparse set was calculated from 3D surface reconstructions. Selection of contours was globally optimized using coarse to fine search. Sparse and dense reconstructions were compared using maximum error, standard deviation error, and surface coverage. For all speech sounds, maximum error was less than 1.5 mm, standard deviation error was less than 0.32 mm, and average reconstruction coverage was 80%. To generalize the method across subjects, optimal slice locations were calculated from only the midsagittal contour. Six midsagittal points were optimized to reconstruct the midsagittal contour. Corresponding coronal slices were then used to reconstruct 3D surfaces. For data collection planning, a midsagittal sample can be collected first and optimal coronal slices can be determined from it. Errors and reconstruction coverage from the midsagittal source set were comparable to the optimized coronal sparse set. These sparse surfaces reconstructed static 3D surfaces, and should be usable for motion sequences as well.

Adult↗

PubMedDate not supplied

Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction.

BACKGROUND: The focus of most anterior cruciate ligament reconstructions has been on replacing the anteromedial bundle and not the posterolateral bundle. HYPOTHESIS: Anatomic two-bundle reconstruction restores knee kinematics more closely to normal than does single-bundle reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Ten cadaveric knees were subjected to external loading conditions: 1) a 134-N anterior tibial load and 2) a combined rotatory load of 5-N x m internal tibial torque and 10-N x m valgus torque. Resulting knee kinematics and in situ force in the anterior cruciate ligament or replacement graft were determined by using a robotic/universal force-moment sensor testing system for 1) intact, 2) anterior cruciate ligament deficient, 3) single-bundle reconstructed, and 4) anatomically reconstructed knees. RESULTS: Anterior tibial translation for the anatomic reconstruction was significantly closer to that of the intact knee than was the single-bundle reconstruction. The in situ force normalized to the intact anterior cruciate ligament for the anatomic reconstruction was 97% +/- 9%, whereas the single-bundle reconstruction was only 89% +/- 13%. With a combined rotatory load, the normalized in situ force for the single-bundle and anatomic reconstructions at 30 degrees of flexion was 66% +/- 40%and 91% +/- 35%, respectively. CONCLUSIONS: Anatomic reconstruction may produce a better biomechanical outcome, especially during rotatory loads. CLINICAL RELEVANCE: Results may lead to the use of a two-bundle technique.

Analysis of Variance↗

PubMed2005

Structural properties of lateral collateral ligament reconstruction at the fibular head.

BACKGROUND: Anatomical reconstruction of a ruptured lateral collateral ligament using allograft tissue secured within the fibular head with an interference screw has been described. HYPOTHESIS: Interference fixation at the fibular head does not reproduce the strength of the intact ligament. STUDY DESIGN: Controlled laboratory study. METHODS: Ten intact lateral collateral ligaments were tested to failure. The distal fixation of 11 ligaments reconstructed with a graft including a bone plug and 11 ligaments reconstructed with a graft without a bone plug were also tested. RESULTS: The reconstructed ligaments consistently failed at the fibular head. The intact specimens predominately failed through ligament rupture. The mean strength and stiffness values were 460 +/- 163 N and 82 +/- 25 N/mm, respectively, for the intact ligaments, 113 +/- 40 N and 36 +/- 10 N/mm, respectively, for reconstruction with a bone plug, and 135 +/- 81 N and 34 +/- 14 N/mm, respectively, for reconstruction without a bone plug. The strength and stiffness were significantly (P < .05) greater for the intact ligaments than for either reconstruction group. The variation in strength was significantly larger for reconstruction without a bone plug than for reconstruction with a bone plug. CONCLUSION: Tension applied to lateral collateral ligaments reconstructed using fibular interference fixation should be limited immediately after surgery. Soft tissue fixation should be employed with care because of the inconsistency in the failure strength. CLINICAL RELEVANCE: Although fibular interference fixation is increasingly being described in the literature, the properties of reconstructed lateral collateral ligaments have not previously been quantified.

Bone Screws↗

PubMedDate not supplied

An in vitro study of an intraarticular and extraarticular reconstruction in the anterior cruciate ligament deficient knee.

The biomechanical effectiveness of an extraarticular ACL reconstruction, an intraarticular ACL reconstruction, and the combination of these on both anterior stability and internal rotational stability of the ACL deficient knee was investigated in six cadaver knees. The extraarticular reconstruction consisted of the Müller anterolateral femorotibial ligament iliotibial band tenodesis, and the intraarticular reconstruction used the middle third of the patellar tendon in the manner of Clancy. The extraarticular reconstruction was found to overconstrain internal tibial rotation of the ACL excised knee between 30 degrees and 90 degrees (P less than 0.05). While the isolated extraarticular reconstruction did not return normal anterior stability to the ACL deficient knee (P less than 0.05), it did significantly reduce the anterior laxity of the ACL deficient knee between 30 degrees and 90 degrees of knee flexion (P less than 0.05). For the combined reconstruction, the intraarticular procedure was performed and then only enough tension was applied to the extraarticular reconstruction to take up slack in the tenodesis without shifting the rotatory position of the tibia from that produced by the intraarticular procedure alone. Neither the intraarticular reconstruction nor the combined procedure resulted in any significant shifts from normal (P less than 0.05) in the rotatory position of the unloaded tibia; during loading neither resulted in rotational displacements significantly different from normal; and both of these procedures reduced the increased anterior laxity of the ACL deficient knee to a level not statistically different from normal. Because the extraarticular reconstruction shared the load when performed with the intraarticular reconstruction as part of a combined procedure, we concluded that it would be useful as an adjunctive procedure in appropriate clinical situations.

Adult↗

PubMed1990

[An improvement on the two-dimensional convolution method of image reconstruction and its application to SPECT].

In single-photon emission computed tomography (SPECT) and X-ray CT one-dimensional (1-D) convolution method is used for their image reconstruction from projections. The method makes a 1-D convolution filtering on projection data with a 1-D filter in the space domain, and back projects the filtered data for reconstruction. Images can also be reconstructed by first forming the 2-D backprojection images from projections and then convoluting them with a 2-D space-domain filter. This is the reconstruction by the 2-D convolution method, and it has the opposite reconstruction process to the 1-D convolution method. Since the 2-D convolution method is inferior to the 1-D convolution method in speed in reconstruction, it has no practical use. In the actual reconstruction by the 2-D convolution method, convolution is made on a finite plane which is called convolution window. A convolution window of size N X N needs a 2-D discrete filter of the same size. If better reconstructions are achieved with small convolution windows, the reconstruction time for the 2-D convolution method can be reduced. For this purpose, 2-D filters of a simple function form are proposed which can give good reconstructions with small convolution windows. They are here defined on a finite plane, depending on the window size used, although a filter function is usually defined on the infinite plane. They are however set so that they better approximate the property of a 2-D filter function defined on the infinite plane. Filters of size N X N are thus determined. Their value varies with window size. The filters are applied to image reconstructions of SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗