A state-of-the-art guide about the effects of sterilization processes on 3D-printed materials for surgical planning and medical applications: A comparative study.

Surgeons use different medical devices in the surgery, such as patient-specific anatomical models, cutting and positioning guides, or implants. These devices must be sterilized before being used in the operation room. There are many sterilization processes available, with autoclave, hydrogen peroxide, and ethylene oxide being the most common in hospital settings. Each method has both advantages and disadvantages in terms of mechanics, chemical interaction, and post-treatment accuracy. The aim of the present study is to evaluate the dimensional and mechanical effect of the most commonly used sterilization techniques available in clinical settings, i.e., Autoclave 121, Autoclave 134, and hydrogen peroxide (HPO), on 11 of the most used 3D-printed materials fabricated using additive manufacturing technologies. The results showed that the temperature (depending on the sterilization method) and the exposure time to that temperature influence not only the mechanical behavior but also the original dimensioning planned on the 3D model. Therefore, HPO is a better overall option for most of the materials evaluated. Finally, based on the results of the study, a recommendation guide on sterilization methods per material, technology, and clinical application is presented.

Naxitamab Combined with Granulocyte-Macrophage Colony-Stimulating Factor as Consolidation for High-Risk Neuroblastoma Patients in First Complete Remission under Compassionate Use-Updated Outcome Report.

Naxitamab is an anti-GD2 antibody approved for the treatment of relapsed/refractory HR-NB. We report the survival, safety, and relapse pattern of a unique set of HR-NB patients consolidated with naxitamab after having achieved first CR. Eighty-two patients were treated with 5 cycles of GM-CSF for 5 days at 250 µg/m2/day (-4 to 0), followed by GM-CSF for 5 days at 500 µg/m2/day (1-5) and naxitamab at 3 mg/kg/day (1, 3, 5), on an outpatient basis. All patients but one were older than 18 months at diagnosis and had stage M; 21 (25.6%) pts had MYCN-amplified (A) NB; and 12 (14.6%) detectable MRD in the BM. Eleven (13.4%) pts had received high-dose chemotherapy and ASCT and 26 (31.7%) radiotherapy before immunotherapy. With a median follow-up of 37.4 months, 31 (37.8%) pts have relapsed. The pattern of relapse was predominantly (77.4%) an isolated organ. Five-year EFS and OS were 57.9% (71.4% for MYCN A) 95% CI = (47.2, 70.9%); and 78.6% (81% for MYCN A) 95% CI = (68.7%, 89.8%), respectively. EFS showed significant differences for patients having received ASCT (p = 0.037) and pre-immunotherapy MRD (p = 0.0011). Cox models showed only MRD as a predictor of EFS. In conclusion, consolidation with naxitamab resulted in reassuring survival rates for HR-NB patients after end-induction CR.

Exploring the Potential of Three-Dimensional Imaging, Printing, and Modeling in Pediatric Surgical Oncology: A New Era of Precision Surgery.

Pediatric surgical oncology is a technically challenging field that relies on CT and MRI as the primary imaging tools for surgical planning. However, recent advances in 3D reconstructions, including Cinematic Rendering, Volume Rendering, 3D modeling, Virtual Reality, Augmented Reality, and 3D printing, are increasingly being used to plan complex cases bringing new insights into pediatric tumors to guide therapeutic decisions and prognosis in different pediatric surgical oncology areas and locations including thoracic, brain, urology, and abdominal surgery. Despite this, challenges to their adoption remain, especially in soft tissue-based specialties such as pediatric surgical oncology. This work explores the main innovative imaging reconstruction techniques, 3D modeling technologies (CAD, VR, AR), and 3D printing applications through the analysis of three real cases of the most common and surgically challenging pediatric tumors: abdominal neuroblastoma, thoracic inlet neuroblastoma, and a bilateral Wilms tumor candidate for nephron-sparing surgery. The results demonstrate that these new imaging and modeling techniques offer a promising alternative for planning complex pediatric oncological cases. A comprehensive analysis of the advantages and limitations of each technique has been carried out to assist in choosing the optimal approach.

Patient-Specific 3D Printed Soft Models for Liver Surgical Planning and Hands-On Training.

Background: Pre-surgical simulation-based training with three-dimensional (3D) models has been intensively developed in complex surgeries in recent years. This is also the case in liver surgery, although with fewer reported examples. The simulation-based training with 3D models represents an alternative to current surgical simulation methods based on animal or ex vivo models or virtual reality (VR), showing reported advantages, which makes the development of realistic 3D-printed models an option. This work presents an innovative, low-cost approach for producing patient-specific 3D anatomical models for hands-on simulation and training. Methods: The article reports three paediatric cases presenting complex liver tumours that were transferred to a major paediatric referral centre for treatment: hepatoblastoma, hepatic hamartoma and biliary tract rhabdomyosarcoma. The complete process of the additively manufactured liver tumour simulators is described, and the different steps for the correct development of each case are explained: (1) medical image acquisition; (2) segmentation; (3) 3D printing; (4) quality control/validation; and (5) cost. A digital workflow for liver cancer surgical planning is proposed. Results: Three hepatic surgeries were planned, with 3D simulators built using 3D printing and silicone moulding techniques. The 3D physical models showed highly accurate replications of the actual condition. Additionally, they proved to be more cost-effective in comparison with other models. Conclusions: It is demonstrated that it is possible to manufacture accurate and cost-effective 3D-printed soft surgical planning simulators for treating liver cancer. The 3D models allowed for proper pre-surgical planning and simulation training in the three cases reported, making it a valuable aid for surgeons.

Advanced Strategies for the Fabrication of Multi-Material Anatomical Models of Complex Pediatric Oncologic Cases.

The printing and manufacturing of anatomical 3D models has gained popularity in complex surgical cases for surgical planning, simulation and training, the evaluation of anatomical relations, medical device testing and patient-professional communication. 3D models provide the haptic feedback that Virtual or Augmented Reality (VR/AR) cannot provide. However, there are many technologies and strategies for the production of 3D models. Therefore, the aim of the present study is to show and compare eight different strategies for the manufacture of surgical planning and training prototypes. The eight strategies for creating complex abdominal oncological anatomical models, based on eight common pediatric oncological cases, were developed using four common technologies (stereolithography (SLA), selectie laser sinterning (SLS), fused filament fabrication (FFF) and material jetting (MJ)) along with indirect and hybrid 3D printing methods. Nine materials were selected for their properties, with the final models assessed for application suitability, production time, viscoelastic mechanical properties (shore hardness and elastic modulus) and cost. The manufacturing and post-processing of each strategy is assessed, with times ranging from 12 h (FFF) to 61 h (hybridization of FFF and SLS), as labor times differ significantly. Cost per model variation is also significant, ranging from EUR 80 (FFF) to EUR 600 (MJ). The main limitation is the mimicry of physiological properties. Viscoelastic properties and the combination of materials, colors and textures are also substantially different according to the strategy and the intended use. It was concluded that MJ is the best overall option, although its use in hospitals is limited due to its cost. Consequently, indirect 3D printing could be a solid and cheaper alternative.

Bowel obstruction following pediatric abdominal cancer surgery.

INTRODUCTION: Pediatric bowel obstruction after intra-abdominal cancer surgery is relatively frequent. Few publications have specifically addressed this significant complication. The purpose of this study was to assess the frequency, etiology and treatment options of bowel obstructions following abdominal cancer surgery in children using our institutional database. MATERIALS AND METHODS: We retrospectively analyzed a single tertiary pediatric hospital database over a 10-year period. The clinical characteristics of patients with and without bowel obstruction were compared using bivariate analyses. The details of the conservative and operative management of bowel obstructions were evaluated. RESULTS: Out of 130 eligible patients, 18 (13.8%) developed bowel obstruction in a mean follow-up of 5.7 years. Patients who developed bowel obstruction were more likely to have received preoperative radiation therapy (16.7 vs 2.7%, p = 0.036) and had longer operative time (398 vs 268 min, p = 0.022). Non-operative management was successful in 39% of patients (7/18). When patients needed surgical intervention, minimally invasive approach was attempted and successfully performed in 36% of cases (4/11), none of which required conversion to laparotomy nor presented with recurrent bowel obstruction. CONCLUSION: Bowel obstruction is a frequent complication after abdominal cancer surgery in children. Conservative management is frequently successful. For patients requiring surgical treatment, laparoscopy remains a valuable option and should be considered in selected cases.

Prognostic value of patient-derived xenograft engraftment in pediatric sarcomas.

The goals of this work were to identify factors favoring patient-derived xenograft (PDX) engraftment and study the association between PDX engraftment and prognosis in pediatric patients with Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma. We used immunodeficient mice to establish 30 subcutaneous PDX from patient tumor biopsies, with a successful engraftment rate of 44%. Age greater than 12 years and relapsed disease were patient factors associated with higher engraftment rate. Tumor type and biopsy location did not associate with engraftment. PDX models retained histology markers and most chromosomal aberrations of patient samples during successive passages in mice. Model treatment with irinotecan resulted in significant activity in 20 of the PDXs and replicated the response of rhabdomyosarcoma patients. Successive generations of PDXs responded similarly to irinotecan, demonstrating functional stability of these models. Importantly, out of 68 tumor samples from 51 patients with a median follow-up of 21.2 months, PDX engraftment from newly diagnosed patients was a prognostic factor significantly associated with poor outcome (p = 0.040). This association was not significant for relapsed patients. In the subgroup of patients with newly diagnosed Ewing sarcoma classified as standard risk, we found higher risk of relapse or refractory disease associated with those samples that produced stable PDX models (p = 0.0357). Overall, our study shows that PDX engraftment predicts worse outcome in newly diagnosed pediatric sarcoma patients.

Synchronous choroid plexus papilloma and Wilms tumor in a girl, disclosing a Li-Fraumeni syndrome.

BACKGROUND: Li-Fraumeni Syndrome (LFS) is a cancer predisposition syndrome characterized by the early-onset of multiple primary cancers which can occur at different moments (metachronous onset) or, more rarely, coincidentally (synchronous onset). Here we describe a previously unreported patient with presentation of synchronous Wilms tumor and Choroid plexus papilloma, leading to the diagnosis of a Li-Fraumeni Syndrome (LFS). CASE PRESENTATION: A 6-year-old girl without previous complains presented with abdominal pain. Abdominal US and MRI showed a left renal tumor with subcapsular hematoma. Due to mild headaches, the diagnostic workup included a brain MRI that unexpectedly identified a large left parietal lobe tumor. Histopathological analysis determined the diagnosis of classic Wilms tumor and choroid-plexus papilloma (CPP), respectively. Both neoplasms showed intense nuclear p53 immunostaining associated with the pathogenic TP53 mutation c.844C > T (p.Arg282Trp). Our patient and her father shared the same heterozygous germline TP53 mutation, confirming the diagnosis of familiar Li-Fraumeni syndrome in the girl. The treatment was tailored to simultaneous tumor presentations. CONCLUSIONS: LFS has been associated with Choroid plexus carcinoma (CPC), but rarely with CPP as in our patient. That suggests that it may be advisable to consider the possibility of analyzing TP53 mutation, not only in all patients with CPC, but also in some patients with CPP, especially when histological or clinical evidences point out to perform this study. The dissimilar presentation of LFS among our patient's father, not having so far any neoplasia diagnosed, while her daughter presented precociously with two simultaneous different tumors, could be related to possible effects of modifier genes on the underlying mutant p53 genotype.

Midline Cervical Cleft: An Anatomical Finding and a Proposal for a New Approach.

Congenital midline cervical cleft is a rare malformation. Typical case shows an area of hypotrophic skin, a cranial nipple-like structure, and a caudal blind sinus. Cervical extension is limited. Relapse of the retraction is common following cutaneous z-plasty. The aim of this study is to describe the radiological, surgical, and histological findings of the 4 cases treated in our center in the last 8 years and communicate the finding of a contractile structure, anterior to the platysma, composed by striated muscle, figure not previously described. This distinct muscular band is responsible for neck retraction. Removal of this releases cervical tension and is essential to avoid the relapse.

Use of patient derived orthotopic xenograft models for real-time therapy guidance in a pediatric sporadic malignant peripheral nerve sheath tumor.

BACKGROUND: The aim of this study was to test the feasibility and utility of developing patient-derived orthotopic xenograft (PDOX) models for patients with malignant peripheral nerve sheath tumors (MPNSTs) to aid therapeutic interventions in real time. PATIENT & METHODS: A sporadic relapsed MPNST developed in a 14-year-old boy was engrafted in mice, generating a PDOX model for use in co-clinical trials after informed consent. SNP-array and exome sequencing was performed on the relapsed tumor. Genomics, drug availability, and published literature guided PDOX treatments. RESULTS: A MPNST PDOX model was generated and expanded. Analysis of the patient's relapsed tumor revealed mutations in the MAPK1, EED, and CDK2NA/B genes. First, the PDOX model was treated with the same therapeutic regimen as received by the patient (everolimus and trametinib); after observing partial response, tumors were left to regrow. Regrown tumors were treated based on mutations (palbociclib and JQ1), drug availability, and published literature (nab-paclitaxel; bevacizumab; sorafenib plus doxorubicin; and gemcitabine plus docetaxel). The patient had a lung metastatic relapse and was treated according to PDOX results, first with nab-paclitaxel, second with sorafenib plus doxorubicin after progression, although a complete response was not achieved and multiple metastasectomies were performed. The patient is currently disease free 46 months after first relapse. CONCLUSION: Our results indicate the feasibility of generating MPNST-PDOX and genomic characterization to guide treatment in real time. Although the treatment responses observed in our model did not fully recapitulate the patient's response, this pilot study identify key aspects to improve our co-clinical testing approach in real time.

Error traps and culture of safety in pediatric surgical oncology.

This article reviews technical issues to improve surgical safety and avoid surgical errors in pediatric surgical oncology, particularly in the three most common extracranial solid tumors: neuroblastoma, hepatoblastoma and Wilms tumor. The use of adjuvant chemotherapy - when indicated - the use of tumor specific classifications, adequate surgical planning, that may include the use of 3D printable models, improved surgical instruments and technology, and following surgical guidelines, would result in avoiding error, increased safety, and therefore in improved surgical outcomes.

Use of 3D Prototypes for Complex Surgical Oncologic Cases.

INTRODUCTION: Physical 3D models known by the industry as rapid prototyping involve the creation of a physical model from a 3D computer version. In recent years, there has been an increasing number of reports on the use of 3D models in medicine. Printing such 3D models with different materials integrating the many components of human anatomy is technically challenging. In this article, we report our technological developments along with our clinical implementation experience using high-fidelity 3D prototypes of tumors encasing major vessels in anatomically sensitive areas. METHODS: Three patients with tumors encasing major vessels that implied complex surgery were selected for surgical planning using 3D prototypes. 3D virtual models were obtained from routine CT and MRI images. The models, with all their anatomical relations, were created by an expert pediatric radiologist and a surgeon, image by image, along with a computerized-aided design engineer. RESULTS: Surgeons had the opportunity to practice on the model before the surgery. This allowed questions regarding surgical approach; feasibility and potential complications to be raised in advance of the actual procedure. All patients then successfully underwent surgery as planned. CONCLUSION: Having a tumor physically printed in its different main component parts with its anatomical relationships is technically feasible. Since a gross total resection is prognostic in a significant percentage of tumor types, refinements in planning may help achieve greater and safer resections therefore contributing to improve surgical management of complex tumors. In this early experience, 3D prototyping helped significantly in the many aspects of surgical oncology planning.

Risk factors and predictors of severity score and complications of pediatric hemorrhagic cystitis.

PURPOSE: We retrospectively analyzed our institutional incidence of hemorrhagic cystitis, identified risk factors, and examined associations of risk factors with disease severity and genitourinary complication rates. MATERIALS AND METHODS: We reviewed charts of all consecutive pediatric patients treated from 1986 to 2010. We analyzed demographics, underlying diagnosis and treatment data to assess risk factors for hemorrhagic cystitis. We also correlated disease severity scores with clinical predisposing factors, and performed univariate and multivariate analyses to examine associations between risk factors and outcomes. RESULTS: Hemorrhagic cystitis was observed in 97 of 6,119 children (1.6%), most of whom (75%) had severity scores of II or III. Mean ± SD age was 12.2 ± 6.3 years for patients with hemorrhagic cystitis and 10.5 ± 7 years for patients without hemorrhagic cystitis (p = 0.017). On univariate analysis increased risk of hemorrhagic cystitis was significantly associated with age greater than 5 years, male gender, cyclophosphamide or busulfan chemotherapy, bone marrow or peripheral blood stem cell transplantation, pelvic radiotherapy and underlying diagnoses of rhabdomyosarcoma, acute leukemia and aplastic anemia. On multivariate analysis age greater than 5 years, allogeneic bone marrow or peripheral blood stem cell transplantation and pelvic radiotherapy were significantly associated with increased risk of hemorrhagic cystitis. Older age, late onset hemorrhagic cystitis, positive urine culture for BK virus and bone marrow or peripheral blood stem cell transplantation were associated with greater disease severity. Patients with higher severity scores more frequently experienced bladder perforation, hydronephrosis, overall hemorrhagic cystitis complications, and increased creatinine and blood urea nitrogen levels during followup. CONCLUSIONS: Older age, previous bone marrow or peripheral blood stem cell transplantation and BK virus in the urine are risk factors for hemorrhagic cystitis and are associated with a higher severity score. Higher severity scores are associated with increased rates of genitourinary complications and renal impairment.

Airway and vascular maturation stimulated by tracheal occlusion do not correlate in the rabbit model of diaphragmatic hernia.

BACKGROUND: In animal models of congenital diaphragmatic hernia (CDH), tracheal occlusion (TO) has induced maturation of both airway spaces and vascular structures. Airway and vascular response to TO are assumed to occur in parallel. This study aims to describe and measure the relationship between airway and vascular maturation induced by TO. METHODS: A rabbit model of CDH on gestational day (GD) 23 and TO on GD 28 (term = GD 31) has been used. Two study groups have been defined: DH (diaphragmatic hernia) and TO (DH treated with TO). Animals were collected on GD 30 and blood flow data of the pulmonary artery (pulsatility index (PI) and fractional moving blood volume) were ultrasonographically measured. Lung morphometry consisted of measurements of radial alveolar count (RAC) and arterial muscular thickness. RESULTS: Animals in the DH group (n = 9) had the worst hemodynamic parameters; their lungs were hypoplastic and had the thickest arterial muscular layer. Animals in the TO group (n = 10) had all these effects reversed. There were no correlations among hemodynamic, airway, and vascular parameters, except for RAC and PI (r = -0.528, P = 0.043). CONCLUSION: Airway and vascular maturation after TO appear to be uncorrelated effects. TO could trigger several pathways that separately regulate airway and vascular responses.

Transitional cell carcinoma of the bladder in children and adolescents: six-case series and review of the literature.

OBJECTIVE: Lower urinary tract tumours are uncommon in paediatrics. Transitional cell carcinoma of the bladder (TCCB) is rarely found in the first two decades of life and is exceptional under 10 years of age. The present series aimed to expand the number of reported cases in the literature. PATIENTS AND METHODS: In 1984-2007, six patients (four male, two female), aged 6, 9, 12, 13, 14 and 17 years, were treated at our centre. Clinical presentation was macroscopic haematuria in five and pyelonephritis in one. Physical examination, laboratory analysis, ultrasound and cystoscopy were performed before surgical treatment in all patients. Follow up was by clinical and ultrasound assessment. RESULTS: Neither physical examination nor laboratory analysis revealed any significant abnormalities, but ultrasound showed exophytic intravesical lesions. Surgical resection was performed endoscopically. Histological studies showed grade I TCCB in all cases. The immediate postoperative period was uneventful and long-term follow up did not reveal recurrence. CONCLUSION: Despite its low incidence in children, TCCB must be suspected in the event of macroscopic haematuria. Ultrasound followed by cystoscopy are the ideal diagnostic tools for visualization of these tumours. Endoscopic resection proved effective in all the present cases. Follow up must be clinical with periodic ultrasound evaluation. Urine cytologic examination is ineffective. Periodic cystoscopy is indicated only in cases of clinical or ultrasonographic suspicion of recurrence.

Heminephroureterectomy for duplex kidney: laparoscopy versus open surgery.

OBJECTIVE: To report our experience of laparoscopic heminephroureterectomy (Hnu) in pediatric patients with duplex anomalies, in comparison to open surgery. PATIENTS AND METHODS: Retrospective review of data from patients who underwent Hnu from 2005 to 2008 was performed. The patients were divided into two groups: laparoscopic (LHnu) and open surgery (OHnu). Laparoscopic surgery was performed by transperitoneal approach in majority of cases. Open surgery was performed by retroperitoneal approach in all cases. RESULTS: Group LHnu: nine patients (8 females, 1 male) with median age of 14 months (range 3-205). Transperitoneal approach was performed in eight patients. Mean operative time was 182 min (CI 95% 146-217). No conversion to open surgery was necessary and there were no complications. Mean hospital stay was 2.44 days (CI 95% 1.37-3.52). Group OHnu: eight patients (3 females, 5 males) underwent nine heminephrectomies at median age of 6.9 months (range 1-12). Mean operating time was 152 min (CI 95% 121-183). There were no complications and mean hospital stay was 4.38 (CI 95% 2.59-6.16) days. Statistical analysis showed no statistically significant difference (P>0.05) in operating time between groups while mean hospital stay was significant (P=0.021). CONCLUSION: The laparoscopic approach is feasible, safe, reduces hospital stay, does not increase operating time and has better cosmetic results. We believe this should be the first option for heminephrectomy.

Lung tissue blood perfusion changes induced by in utero tracheal occlusion in a rabbit model of congenital diaphragmatic hernia.

OBJECTIVE: To analyze the impact of in utero tracheal occlusion (TO) on lung tissue blood perfusion, as measured by fractional moving blood volume (FMBV) and conventional spectral Doppler, in a rabbit model of congenital diaphragmatic hernia (CDH). METHODS: In 50 fetal rabbits, a left CDH was surgically created at 23 days of gestational age (GA). At 28 days of GA, the surviving CDH fetuses were randomly assigned to undergo either TO (CDH+TO group) or a sham operation (CDH group). Twenty littermates, which were not operated on, served as internal normal controls. At 30 days of GA, lung perfusion estimated by FMBV and spectral Doppler of the proximal intrapulmonary artery were evaluated in the right lung during cesarean section. Doppler waveform analysis included the pulsatility index (PI), peak early diastolic reverse flow and peak systolic velocity. RESULTS: Eleven CDH fetuses, 9 CDH+TO and 20 controls were suitable for the study. CDH fetuses showed a significantly higher PI [8.0 (SD 1.8) vs. 5.22 (SD 1.1), p < 0.001] and lower FMBV [13.5% (SD 4.6) vs. 23.0% (SD 2.1), p < 0.001] than the controls. In contrast, CDH+TO fetuses had a significantly lower PI [5.8 (SD 2.3) vs. 8.0 (SD 1.8), p = 0.015] and higher FMBV [27.6% (SD 7.1) vs. 13.5% (SD 4.6), p < 0.001] than CDH fetuses, with values similar to the controls. Peak early diastolic reverse flow and peak systolic velocity showed nonsignificant differences among the study groups. The lung to body weight ratio at necropsy correlated positively with lung FMBV (r = 0.60, p < 0.001) and negatively with the pulmonary artery PI (r = -0.48, p < 0.01). CONCLUSION: Tracheal occlusion is consistently associated with increased lung tissue perfusion and decreased intrapulmonary impedance in a rabbit model of CDH.