A three-dimensional printed customized bolus: adapting to the shape of the outer ear.

BACKGROUND: The skin-sparing effect of megavoltage-photon beams in radiotherapy (RT) reduces the target coverage of superficial tumours. Consequently, a bolus is widely used to enhance the target coverage for superficial targets. This study evaluates a three-dimensional (3D)-printed customized bolus for a very irregular surface, the outer ear. MATERIALS AND METHODS: We fabricated a bolus using a computed tomography (CT) scanner and evaluated its efficacy. The head of an Alderson Rando phantom was scanned with a CT scanner. Two 3D boluses of 5- and 10-mm thickness were designed to fit on the surface of the ear. They were printed by the Stratasys Objet260 Connex3 using the malleable "rubber-like" photopolymer Agilus. CT simulations of the Rando phantom with and without the 3D and commercial high density boluses were performed to evaluate the dosimetric properties of the 3D bolus. The prescription dose to the outer ear was 50 Gy at 2 Gy/fraction. RESULTS: We observed that the target coverage was slightly better with the 3D bolus of 10mm compared with the commercial one (D98% 98.2% vs. 97.6%).The maximum dose was reduced by 6.6% with the 3D bolus and the minimum dose increased by 5.2% when comparing with the commercial bolus. In addition, the homogeneity index was better for the 3D bolus (0.041 vs. 0.073). CONCLUSION: We successfully fabricated a customized 3D bolus for a very irregular surface. The target coverage and dosimetric parameters were at least comparable with a commercial bolus. Thus, the use of malleable materials can be considered for the fabrication of customized boluses in cases with complex anatomy.

Affordable Three-Dimensional Printed Heart Models.

This is a 7-years single institution study on low-cost cardiac three-dimensional (3D) printing based on the use of free open-source programs and affordable printers and materials. The process of 3D printing is based on several steps (image acquisition, segmentation, mesh optimization, slicing, and three-dimensional printing). The necessary technology and the processes to set up an affordable three-dimensional printing laboratory are hereby described in detail. Their impact on surgical and interventional planning, medical training, communication with patients and relatives, patients' perception on care, and new cardiac device development was analyzed. A total of 138 low-cost heart models were designed and printed from 2013 to 2020. All of them were from different congenital heart disease patients. The average time for segmentation and design of the hearts was 136 min; the average time for printing and cleaning the models was 13.5 h. The average production cost of the models was €85.7 per model. This is the most extensive series of 3D printed cardiac models published to date. In this study, the possibility of manufacturing three-dimensional printed heart models in a low-cost facility fulfilling the highest requirements from a technical and clinical point of view is demonstrated.

Donor-recipient matching in hand transplantation: a comparison of anthropometric measurements, 3-dimensional virtual models and printed epitheses.

Donor-recipient matching in hand transplantation remains challenging. The usefulness of three-dimensional (3-D) virtual models and printed epitheses were compared with measurements on cadaveric extremities to evaluate the most accurate method of donor-recipient matching for allograft procurement. Ten anthropometric measurements were recorded from 12 human cadaveric upper extremities and matched to printed epitheses and 3-D virtual models. Five circumferential and two longitudinal measurements obtained an intra-class correlation of >0.75 with all three methods, with the Kaplan (0.973) and wrist circumferences (0.942) achieving the highest concordance. Measurement on cadaveric specimens was the most reliable method. Using different combinations of donor hand and recipient forearms, a series of 72 virtual transplantations were then created, and their compatibility rated by ten transplant surgeons. The results confirmed that anthropometric measurements, obtained directly from potential human donor limbs and based on wrist circumference as the primary parameter, provide the best and most clinically relevant donor-recipient match.

Trends in burn injury mortality in Spain (1979-2018): Sex-specific age-cohort-period effects.

BACKGROUND: Previous studies about burns mortality are often exclusively based on hospital and burn centre data. National population-based reports on this topic are rather limited. The aim of this study was to analyse sex- and age-specific mortality rates of burns in Spain during the period 1979-2018. METHODS: Age-standardised burns mortality rates were calculated from death records and mid-year population data were provided by the Spanish National Statistics Institute. Joinpoint regression analyses were used to identify significant points of change in trends over time and to compute average annual per cent change (AAPC). Age, period and cohort effects were also analysed. RESULTS: Mortality due to burn injury decreased in both sexes between 1979 and 2018: from the first quinquennium of this period up to the last one age-adjusted mortality rates decreased from 1.37 to 0.49 per 100,000 in men and from 0.96 to 0.26 per 100,000 in women. CONCLUSIONS: Burns mortality rates in Spain have been decreasing during the last decades. Promotion of primary prevention measures should continue.

Diagnostic accuracy of a telemedicine tool for acute burns diagnosis.

BACKGROUND: Telemedicine technologies have a valuable potential when it comes to improving the accuracy of triage protocols in selecting severely injured patients who may benefit from transportation. The main objective of this study was to evaluate the correlation of the urgent diagnosis made by telemedicine through an App with traditional face-to-face urgent care and the final diagnosis, made by scheduled consultation. METHODS: We carried out a descriptive cross-sectional study to evaluate the accuracy of telemedicine in burns evaluation compared to gold standard (in-person consultation). An App was designed. All patients enrolled were evaluated by both teleconsultation and face-to-face approach on burn emergencies. Diagnosis on presentation made by a physician constituted the gold standard. RESULTS: A total of 202 patients were included in the study. The use of TM was able to detect that 83.17% of the patients attending the BU could have been managed on as outpatient basis. The intra-observer concordance was k=0.94 (95% CI: 0.90-0.97). These results highlight a very high sensitivity and specificity (99.40 and 100% respectively). CONCLUSIONS: The telemedicine system for planning referrals is a useful tool that may make significant differences in the management of burned patients although further research needs to be taken in that direction.

Pediatric extremity bone sarcoma reconstruction with the vascularized fibula flap: Observational study assessing long-term functional outcomes, complications, and survival.

BACKGROUND: Limb salvage is important in pediatric patients with bone sarcomas. The vascularized fibula flap is a versatile option, combined or not with a bone allograft. The authors evaluated the functional long-term outcomes, complications, and survival of using this technique in pediatric patients. METHODS: A retrospective review of 27 pediatric patients reconstructed between 2011 and 2018 with the fibula flap after bone sarcoma resection was conducted. Long-term functional outcomes, complications, and survival were assessed. Variables analyzed were age, sex, Capanna technique, follow-up, complications, additional surgeries, time to weight bearing, length discrepancy, and sport practice. RESULTS: Twenty-seven patients with a mean age of 9.3 years were included. The mean follow-up was 44.33 months. The Capanna technique was performed in 15 patients. All extremities but one were salvaged. The overall complication rate was 74.07%. Fibula fracture and nonunion rates were 34.04% and 11.11%, respectively. Partial weight bearing was resumed at a mean of 9.07 months. About 79.17% of patients with a 12-month follow-up achieved full weight bearing. An age below 8 years was significantly associated with a lower major complication rate and a shorter time to weight bearing and full weight bearing. Major complications and additional surgeries were significantly associated with longer periods until weight bearing and full weight bearing. CONCLUSIONS: The fibula flap allows the majority of extremities to be reconstructed. However, a high rate of complications and additional surgeries should be anticipated. Full weight bearing is usually achieved within the first year, with modest functional increase afterward. Less complications and a faster functional recovery are expected in patients below the age of 8 years.

Comparison of different constitutive models to characterize the viscoelastic properties of human abdominal adipose tissue. A pilot study.

Knowing the mechanical properties of human adipose tissue is key to simulate surgeries such as liposuction, mammoplasty and many plastic surgeries in which the subcutaneous fat is present. One of the most important surgeries, for its incidence, is the breast reconstruction surgery that follows a mastectomy. In this case, achieving a deformed shape similar to the healthy breast is crucial. The reconstruction is most commonly made using autologous tissue, taken from the patient's abdomen. The amount of autologous tissue and its mechanical properties have a strong influence on the shape of the reconstructed breast. In this work, the viscoelastic mechanical properties of the human adipose tissue have been studied. Uniaxial compression stress relaxation tests were performed in adipose tissue specimens extracted from the human abdomen. Two different viscoelastic models were used to fit to the experimental tests: a quasi-linear viscoelastic (QLV) model and an internal variables viscoelastic (IVV) model; each one with four different hyperelastic strain energy density functions to characterise the elastic response: a 5-terms polynomial function, a first order Ogden function, an isotropic Gasser-Ogden-Holzapfel function and a combination of a neoHookean and an exponential function. The IVV model with the Ogden function was the best combination to fit the experimental tests. The viscoelastic properties are not important in the simulation of the static deformed shape of the breast, but they are needed in a relaxation test performed under finite strain rate, particularly, to derive the long-term behaviour (as time tends to infinity), needed to estimate the static deformed shape of the breast. The so obtained stiffness was compared with previous results given in the literature for adipose tissue of different regions, which exhibited a wide dispersion.

Three-dimensional printed models for surgical planning of complex congenital heart defects: an international multicentre study.

OBJECTIVES: To evaluate the impact of 3D printed models (3D models) on surgical planning in complex congenital heart disease (CHD). METHODS: A prospective case-crossover study involving 10 international centres and 40 patients with complex CHD (median age 3 years, range 1 month-34 years) was conducted. Magnetic resonance imaging and computed tomography were used to acquire and segment the 3D cardiovascular anatomy. Models were fabricated by fused deposition modelling of polyurethane filament, and dimensions were compared with medical images. Decisions after the evaluation of routine clinical images were compared with those after inspection of the 3D model and intraoperative findings. Subjective satisfaction questionnaire was provided. RESULTS: 3D models accurately replicate anatomy with a mean bias of -0.27 ± 0.73 mm. Ninety-six percent of the surgeons agree or strongly agree that 3D models provided better understanding of CHD morphology and improved surgical planning. 3D models changed the surgical decision in 19 of the 40 cases. Consideration of a 3D model refined the planned biventricular repair, achieving an improved surgical correction in 8 cases. In 4 cases initially considered for conservative management or univentricular palliation, inspection of the 3D model enabled successful biventricular repair. CONCLUSIONS: 3D models are accurate replicas of the cardiovascular anatomy and improve the understanding of complex CHD. 3D models did not change the surgical decision in most of the cases (21 of 40 cases, 52.5% cases). However, in 19 of the 40 selected complex cases, 3D model helped redefining the surgical approach.

Validation of a method for retroperitoneal tumor segmentation.

PURPOSE: In 2005, an application for surgical planning called AYRA[Formula: see text] was designed and validated by different surgeons and engineers at the Virgen del Rocío University Hospital, Seville (Spain). However, the segmentation methods included in AYRA and in other surgical planning applications are not able to segment accurately tumors that appear in soft tissue. The aims of this paper are to offer an exhaustive validation of an accurate semiautomatic segmentation tool to delimitate retroperitoneal tumors from CT images and to aid physicians in planning both radiotherapy doses and surgery. METHODS: A panel of 6 experts manually segmented 11 cases of tumors, and the segmentation results were compared exhaustively with: the results provided by a surgical planning tool (AYRA), the segmentations obtained using a radiotherapy treatment planning system (Pinnacle[Formula: see text]), the segmentation results obtained by a group of experts in the delimitation of retroperitoneal tumors and the segmentation results using the algorithm under validation. RESULTS: 11 cases of retroperitoneal tumors were tested. The proposed algorithm provided accurate results regarding the segmentation of the tumor. Moreover, the algorithm requires minimal computational time-an average of 90.5% less than that required when manually contouring the same tumor. CONCLUSION: A method developed for the semiautomatic selection of retroperitoneal tumor has been validated in depth. AYRA, as well as other surgical and radiotherapy planning tools, could be greatly improved by including this algorithm.

Coverage of supraumbilical abdominal wall defects: The tunnelled-pedicled ALT technique.

Abdominal wall defects are a challenge for reconstructive surgeons. Although the utility of anterolateral thigh perforator (ALT) flap has been well established for lower abdominal wall reconstruction, pedicled ALT flap is usually not considered for supraumbilical defects in the most recent algorithms. The purpose of this paper is to report the results of a tunneled pedicled ALT flap for reconstruction of supraumbilical defect from a series of patients. From July 2009 to September2014, six patients underwent delayed abdominal wall coverage using pedicled ALT flaps and reinforcement with polypropylene meshes. Defects occurred after surgical complications and abdominal trauma. Flaps were tunneled beneath the rectus femoris and sartorius muscles to increase the pedicle length. The size of the skin islands ranged from 22-29 × 10-14 cm. All flaps survived and the healing of the wounds was successful. Partial dehiscence of donor site occurred in one patient, and small wound dehiscence due to minimal distal necrosis was observed in another patient. No functional problems were reported in donor site, and no complications occurred in 6-68 months of follow-up. The tunneled pedicled ALT flap may provide a reliable alternative method for abdominal wall reconstruction, including supraumbilical defects. © 2015 Wiley Periodicals, Inc. Microsurgery 37:119-127, 2017.

Three-dimensional segmentation of retroperitoneal masses using continuous convex relaxation and accumulated gradient distance for radiotherapy planning.

An innovative algorithm has been developed for the segmentation of retroperitoneal tumors in 3D radiological images. This algorithm makes it possible for radiation oncologists and surgeons semiautomatically to select tumors for possible future radiation treatment and surgery. It is based on continuous convex relaxation methodology, the main novelty being the introduction of accumulated gradient distance, with intensity and gradient information being incorporated into the segmentation process. The algorithm was used to segment 26 CT image volumes. The results were compared with manual contouring of the same tumors. The proposed algorithm achieved 90 % sensitivity, 100 % specificity and 84 % positive predictive value, obtaining a mean distance to the closest point of 3.20 pixels. The algorithm's dependence on the initial manual contour was also analyzed, with results showing that the algorithm substantially reduced the variability of the manual segmentation carried out by different specialists. The algorithm was also compared with four benchmark algorithms (thresholding, edge-based level-set, region-based level-set and continuous max-flow with two labels). To the best of our knowledge, this is the first time the segmentation of retroperitoneal tumors for radiotherapy planning has been addressed.

Chimeric Anterolateral Thigh Flap for Total Thoracic Esophageal Reconstruction.

Gastric pull-up is generally the first choice for a total thoracic esophageal reconstruction. Malfunction of this gastric conduit is uncommon, but devastating when it occurs: it causes marked comorbidity to the patient, preventing oral intake and worsening quality of life. Secondary salvage thoracic esophageal reconstruction surgery is usually performed with free or pedicled jejunum flaps or colon interposition. We present a case of a total thoracic esophageal reconstruction with an externally monitored chimeric anterolateral thigh flap, extending from the cervical esophagus to the retrosternal gastroplasty remnant. Intestinal reconstructive techniques were not an available option for this patient.

Features identification for automatic burn classification.

PURPOSE: In this paper an automatic system to diagnose burn depths based on colour digital photographs is presented. JUSTIFICATION: There is a low success rate in the determination of burn depth for inexperienced surgeons (around 50%), which rises to the range from 64 to 76% for experienced surgeons. In order to establish the first treatment, which is crucial for the patient evolution, the determination of the burn depth is one of the main steps. As the cost of maintaining a Burn Unit is very high, it would be desirable to have an automatic system to give a first assessment in local medical centres or at the emergency, where there is a lack of specialists. METHOD: To this aim a psychophysical experiment to determine the physical characteristics that physicians employ to diagnose a burn depth is described. A Multidimensional Scaling Analysis (MDS) is then applied to the data obtained from the experiment in order to identify these physical features. Subsequently, these characteristics are translated into mathematical features. Finally, via a classifier (Support Vector Machine) and a feature selection method, the discriminant power of these mathematical features to distinguish among burn depths is analysed, and the subset of features that better estimates the burn depth is selected. RESULTS: A success rate of 79.73% was obtained when burns were classified as those which needed grafts and those which did not. CONCLUSIONS: Results validate the ability of the features extracted from the psychophysical experiment to classify burns into their depths.

New technologies applied to surgical processes: Virtual Reality and rapid prototyping.

AYRA is software of virtual reality for training, planning and optimizing surgical procedures. AYRA was developed under a research, development and innovation project financed by the Andalusian Ministry of Health, called VirSSPA. Nowadays AYRA has been successfully used in more than 1160 real cases and after proving its efficiency it has been introduced in the clinical practice at the Virgen del Rocío University Hospital . Furthermore, AYRA allows generating physical 3D biomodels using rapid prototyping technology. They are used for surgical planning support, intraoperative reference or defect reconstruction. In this paper, some of these tools and some real cases are presented.

3D printed models for planning endovascular stenting in transverse aortic arch hypoplasia.

OBJECTIVES: To evaluate whether three-dimensional (3D) printed models can be used to improve interventional simulation and planning in patients with aortic arch hypoplasia. BACKGROUND: Stenting of a hypoplastic transverse arch is technically challenging, and complications such as stent migration and partial obstruction of the origin of the head and neck vessels are highly dependent on operator skills and expertise. METHODS: Using magnetic resonance imaging (MRI) data, a 3D model of a repaired aortic coarctation of a 15-year-old boy with hypoplastic aortic arch was printed. Simulation of the endovascular stenting of the hypoplastic arch was carried out under fluoroscopic guidance in the 3D printed model, and subsequently in the patient. A Bland-Altman analysis was used to evaluate the agreement between measurements of aortic diameter in the 3D printed model and the patient's MRI and X-ray angiography. RESULTS: The 3D printed model proved to be radio-opaque and allowed simulation of the stenting intervention. The assessment of optimal stent position, size, and length was found to be useful for the actual intervention in the patient. There was excellent agreement between the 3D printed model and both MRI and X-ray angiographic images (mean bias and standard deviation of 0.36 ± 0.45 mm). CONCLUSIONS: 3D printed models accurately replicate patients' anatomy and are helpful in planning endovascular stenting in transverse arch hypoplasia. This opens a door for potential simulation applications of 3D models in the field of catheterization and cardiovascular interventions.

Three-dimensional patient-specific cardiac model for surgical planning in Nikaidoh procedure.

PURPOSE: To explore the use of three-dimensional patient-specific cardiovascular models using rapid prototyping techniques (fused deposition modelling) to improve surgical planning in patients with complex congenital heart disease. DESCRIPTION: Rapid prototyping techniques are used to print accurate three-dimensional replicas of patients' cardiovascular anatomy based on magnetic resonance images using computer-aided design systems. Models are printed using a translucent polylactic acid polymer. EVALUATION: As a proof of concept, a model of the heart of a 1.5-year-old boy with transposition of the great arteries, ventricular septal defect and pulmonary stenosis was constructed to help planning the surgical correction. The cardiac model allowed the surgeon to evaluate the location and dimensions of the ventricular septal defect as well as its relationship with the aorta and pulmonary artery. CONCLUSIONS: Cardiovascular models constructed by rapid prototyping techniques are extremely helpful for planning corrective surgery in patients with complex congenital malformations. Therefore they may potentially reduce operative time and morbi-mortality.

Virtual reality AYRA software for preoperative planning in facial allotransplantation.

PURPOSE: The purpose of this study was to validate a virtual reality software for the recording of anthropometric measurements as a first step towards matching donors with recipients in the preoperative planning process which precedes the harvest of a facial allograft. METHODS: Anthropometric measurements of both soft and bone tissue were recorded in 5 cryopreserved human heads to compare conventional analogue measurements with digital measurements obtained from 3-dimensional (3D) reconstructions produced using AYRA software. To test the degree of correlation between both measuring methods, intraclass correlation coefficient (ICC) was applied to each pair of measurements. RESULTS: ICCs calculated were greater than 0.6 (substantial or almost perfect correlation) for all of the pairs of variables, with the exception of 2 of the measurements studied in bone tissue. CONCLUSIONS: In facial transplantation, preoperative planning is crucial to select an allograft whose anatomical compatibility with the recipient defect is as close as possible. The dimensions of the potential face donor must be congruent to ensure the procedure's feasibility and the adequate insertion of the allograft into the defect. The recording of anthropometric measurements with the virtual reality software displayed an equivalent correlation to those produced using a conventional analogue method. The 3D reconstructions obtained by using a virtual reality software can play a useful role to facilitate the characterization of the donor face.