Enhancing Distraction Osteogenesis With Carbon Fiber Reinforced Polyether Ether Ketone Bone Pins and a Three-Dimensional Printed Transfer Device to Permit Artifact-Free Three-Dimensional Magnetic Resonance Imaging.

OBJECTIVES: To: (1) design an artifact-free 3D-printed MR-safe temporary transfer device, (2) engineer bone-pins from carbon fiber reinforced polyether ether ketone (CFR-PEEK), (3) evaluate the imaging artifacts of CFR-PEEK, and (4) confirm the osteointegration potential of CFR-PEEK, thus enhancing 3D-planning of bony advancements in hemifacial microsomia using sequential magnetic resonance imaging (MRI). STUDY DESIGN: Engineered CRF-PEEK bone pins and a 3D printed ex-fix device were implanted into a sheep head and imaged with MRI and computed tomography . The osseointegration and bony compatibility potential of CFR-PEEK was assessed with scanning electron microscopy images of MC3T3 preosteoblast cells on the surface of the material. RESULTS: The CFR-PEEK pins resulted in a signal void equivalent to the dimension of the pin, with no adjacent areas of MR-signal loss or computed tomography artifact. MCT3 cells adhered and proliferated on the surface of the discs by forming a monolayer of cells, confirming compatibility and osseointegration potential. CONCLUSION: A 3D printed transfer device could be utilized temporarily during MRI to permit artifact-free 3D planning. CFR-PEEK pins eliminate imaging artifact permitting sequential MRI examination. In combination, this has the potential to enhance distraction osteogenesis, by permitting accurate three-dimensional planning without ionizing radiation.

Three-Dimensional Reconstruction of the Craniofacial Skeleton With Gradient Echo Magnetic Resonance Imaging ("Black Bone"): What Is Currently Possible?

Three-dimensional (3D) reconstructed computed tomography (CT) imaging has become an integral component of craniomaxillofacial patient care. However, with increasing concern regarding the use of ionizing radiation, particularly in children with benign conditions who require repeated examinations, dose reduction and nonionizing alternatives are actively being sought. The "Black Bone" magnetic resonance imaging (MRI) technique provides uniform contrast of the soft tissues to enhance the definition of cortical bone. The aim of this study was to develop methods of 3D rendering of the craniofacial skeleton and to ascertain their accuracy. "Black Bone" MRI datasets acquired from phantoms, adult volunteers and patients were segmented and surface and/or volume rendered using 4 commercially available or open source software packages. Accuracy was explored using a custom phantom (permitting direct measurement), CT and MRI. "Black Bone" MRI datasets were successfully used to create 3D rendered images of the craniofacial skeleton in all 4 software packages. Comparable accuracy was achieved between CT and MRI 3D rendered images of the phantom. The "Black Bone" MRI technique provides a viable 3D alternative to CT examination when imaging the craniofacial skeleton.

"Black Bone" MRI: a potential alternative to CT with three-dimensional reconstruction of the craniofacial skeleton in the diagnosis of craniosynostosis.

OBJECTIVES: To determine the potential of novel gradient echo parameters, "Black Bone" MRI as an alternative to CT in the identification of normal and prematurely fused cranial sutures both in 2D and 3D imaging. METHODS: Thirteen children with a clinical diagnosis of craniosynostosis underwent "Black Bone" MRI in addition to routine cranial CT. "Black Bone" datasets were compared to CT and clinical findings. "Black Bone" imaging was subsequently used to develop 3D reformats of the craniofacial skeleton to enhance further visualisation of the cranial sutures. RESULTS: Patent cranial sutures were consistently identified on "Black Bone" MRI as areas of increased signal intensity. In children with craniosynostosis the affected suture was absent, whilst the remaining patent sutures could be visualised, consistent with CT and clinical findings. Segmentation of the "Black Bone" MRI datasets was successful with both threshold and volume rendering techniques. The cranial sutures, where patent, could be visualised throughout their path. CONCLUSIONS: Patent cranial sutures appear as areas of increased signal intensity on "Black Bone" MRI distinct from the cranial bone, demonstrating considerable clinical potential as a non-ionising alternative to CT in the diagnosis of craniosynostosis. KEY POINTS: • Patent cranial sutures appear hyperintense on "Black Bone" MRI • Prematurely fused cranial sutures are distinct from patent sutures • Minimal soft tissue contrast permits 3D-rendered imaging of the craniofacial skeleton.

A novel use of the rigid external distraction frame: acute on-table distraction with autologous bone grafting.

Distraction osteogenesis with an external distraction device such as the rigid external distraction (RED) frame has become an established method for treating midface hypoplasia. It allows for greater advancement of the midface than achievable with traditional Le Fort III osteotomies; however, there are a number of problems associated with frame application such as pin site migration and need for frame removal. We present 2 cases of the novel use of the RED frame, in both a pediatric patient and an adult patient. The RED frame was used to achieve table soft tissue distraction, greater than previously achievable with traditional Le Fort III osteotomy. This was then combined with acute bone grafting, allowing the RED frame to be removed intraoperatively and thereby removing the complications associated with long-term frame application. We believe this to be the first reported use of the RED frame for acute on-table distraction of the midface. This has allowed far greater advancement of the midface than would be achievable with traditional Le Fort III advancement but, when combined with autologous bone grafting, has allowed intraoperative removal of the frame, thus negating some of the complications of long-term distraction osteogenesis using the RED frame.

Power spectral analysis of the effects of epinephrine, norepinephrine, dobutamine and dopexamine on microcirculation following free tissue transfer.

BACKGROUND: The use of pressor drugs after microsurgical free tissue transfer remains controversial because of potential vasoconstrictor effects on the free flap. Noninvasive monitoring of free flaps with laser Doppler flowmetry may provide further information regarding the local regulation of blood flow in the flap tissues during pressor infusions. This study evaluated the effects of four commonly used pressor agents. METHODS: Twenty four patients (25 data sets) undergoing head and neck cancer resection and free flap reconstruction were recruited. Epinephrine, norepinephrine, dopexamine, and dobutamine were infused in a random order at four infusion rates, after surgery, with free flap and control area (deltoid region) laser Doppler skin blood flow monitoring. Frequency analysis of the Doppler waveform was performed utilizing the time period immediately before the first drug infusion for each patient as baseline. RESULTS: At baseline there was less power at the 0.002-0.6 Hz frequency in the flap compared with control tissue consistent with surgical denervation. At maximum epinephrine infusion rates, the control of blood flow moved toward (i.e., proportion of power increased in) the lower frequencies, as smooth muscle mediated (myogenic) control began to dominate blood flow, an effect most marked with norepinephrine. Dobutamine and dopexamine had little effect on control of blood flow. CONCLUSIONS: Denervation of free flap tissue is demonstrable using spectral analysis of laser Doppler blood flow signals. With norepinephrine the control of blood flow shifts toward low frequency vasomotion where blood flow depends mostly on average blood pressure, making it potentially the most suitable agent following free tissue transfer.

Identification of normal cranial sutures in infants on routine magnetic resonance imaging.

There are increasing concerns relating to the ionizing effects of computed tomography imaging in infants with benign conditions. Magnetic resonance imaging (MRI) is a potential alternative to ionizing radiation when determining patency of the cranial sutures; however, there is no documentation in the literature on the appearance of normal cranial sutures in infants on MRI. This study reviews the appearance of the cranial sutures, their widths, and accuracy of identification in the first year of life on MRI.The coronal, sagittal, and lambdoid sutures were evaluated by 5 assessors on 100 anonymized MRI scans in infants aged 1 to 361 days. The sutures were scored on a 3-point scale. The MRI sequences investigated were axial T1, axial T2, coronal fluid attenuated inversion recovery, axial short tau inversion recovery, and sagittal T1. The suture widths were measured in those cases where they were clearly identifiable, and agreement was obtained in the first aspect of the study (n = 38).A κ score of 0.6 was obtained for interrater agreement. An increasing total score for all sutures with advancing age was found (P < 0.05). The mean suture widths for the coronal, sagittal, and lambdoid sutures were 1.2 (SD, 0.4), 1.4 (SD, 0.4), and 1.3 (SD, 0.3) mm, respectively. There was no significant difference in suture width with age.The appearance of cranial sutures on MRI is as an area of signal void, which may be difficult to clearly define, thus making it unreliable as a standard investigation in the diagnosis of craniosynostosis.

A detailed anatomical assessment of the lateral tongue extrinsic musculature, and proximity to the tongue mucosal surface. Does this confirm the current TNM T4a muscular subclassification?

PURPOSE: The current T4a subclassification of the TNM staging system for oral malignancies has been criticised as based almost exclusively on anatomical data. The aim of this study was to provide anatomical confirmation of the muscular constraints of T4a classification of oral tongue tumours. METHODS: A detailed anatomical study describing and measuring the adjacency of the named extrinsic tongue muscles to the lateral tongue surface was completed on the Visible Human Female (VHF). The distance of styloglossus and hyoglossus to the over lying mucosa were determined. RESULTS: The appearance, position, orientation and anatomical relationships of the lateral tongue extrinsic muscles, with comparison to their classical descriptions are described. The right VHF styloglossus was 1.3 mm (0.33-1.48) and left 2.91 mm (0.66-7.68) from the mucosal surface in the axial plane. The right VHF hyoglossus was 2.93 mm (1.48-4.96) and left 4.33 (1.68-8.71) from the mucosal surface in the axial line. CONCLUSIONS: In the lateral tongue, styloglossus and hyoglossus are very superficial. The inclusion criteria of hyoglossus and styloglossus in the T4a staging does not appear justified based upon their anatomical position.

Functional fibrinogen to platelet ratio using thromboelastography as a predictive parameter for thrombotic complications following free tissue transfer surgery: a preliminary study.

BACKGROUND: Microvascular free tissue transfer in head and neck surgery has become an indispensable tool. Anastomotic thrombosis is one of the leading causes of flap failure; however, there are no validated methods to accurately identify and quantify those patients most at risk of thrombotic complications. The aim of this study was to determine if functional fibrinogen to platelet ratio using thrombelastography could preoperatively identify patients at risk of thrombotic complications. MATERIALS AND METHODS: Twenty nine patients undergoing free tissue transfer surgery for head and neck pathology underwent routine TEG® analysis, with calculation of functional fibrinogen to platelet ratio at induction of anesthesia. All perioperative thrombotic complications were recorded and crossreferenced with preoperative ratios. Data was further compared to results obtained from 42 healthy volunteers. RESULTS: The mean functional fibrinogen to platelet ratio was significantly higher in the surgery group compared to healthy volunteers. Of the 29 patients studied, 31% (n = 9) had some form of thrombotic event, with all but one patient having a ratio ≥42% (mean 47% ± 7%). For those patients without thrombotic events, the mean ratio was 37% ± 5%. CONCLUSION: A functional fibrinogen to platelet ratio above 42% as measured by TEG® may be useful in identifying those patients likely to develop thrombotic complication.

What the general dental practitioner needs to know about HPV-related oropharyngeal malignancy.

The rates of oropharyngeal squamous cell carcinoma have continued to rise secondary to the increasing prevalence of the human papillomavirus (HPV). HPV-related disease is typically found in younger patients who do not have the traditional risk factors for malignancy. General dental practitioners (GDPs) often examine patients regularly and may therefore have an opportunity to identify oropharyngeal malignancies at an early stage. However, many GDPs are unfamiliar with oropharyngeal anatomy, pathology and clinical examination. This review summarises the key points in identifying patients with oropharyngeal malignancy who necessitate urgent referral.

"Black Bone" MRI: a novel imaging technique for 3D printing.

OBJECTIVES: Three-dimensionally printed anatomical models are rapidly becoming an integral part of pre-operative planning of complex surgical cases. We have previously reported the "Black Bone" MRI technique as a non-ionizing alternative to CT. Segmentation of bone becomes possible by minimizing soft tissue contrast to enhance the bone-soft tissue boundary. The objectives of this study were to ascertain the potential of utilizing this technique to produce three-dimensional (3D) printed models. METHODS: "Black Bone" MRI acquired from adult volunteers and infants with craniosynostosis were 3D rendered and 3D printed. A custom phantom provided a surrogate marker of accuracy permitting comparison between direct measurements and 3D printed models created by segmenting both CT and "Black Bone" MRI data sets using two different software packages. RESULTS: "Black Bone" MRI was successfully utilized to produce 3D models of the craniofacial skeleton in both adults and an infant. Measurements of the cube phantom and 3D printed models demonstrated submillimetre discrepancy. CONCLUSIONS: In this novel preliminary study exploring the potential of 3D printing from "Black Bone" MRI data, the feasibility of producing anatomical 3D models has been demonstrated, thus offering a potential non-ionizing alterative to CT for the craniofacial skeleton.

MRI pre-treatment tumour volume in maxillary complex squamous cell carcinoma treated with surgical resection.

UNLABELLED: Tumour volume (Tv) measurements obtained from pre-treatment CT and MRI have increasingly shown to be more reliable predictors of outcome than TNM stage. The aim of this study was to determine the correlation of MRI calculated maxillary complex tumour volume with patient outcome. METHODS: The medical records of 39 patients with squamous cell carcinoma involving the maxillary sinus, maxilla, hard palate and maxillary alveolus were reviewed and tumour volume measurements completed on pre-treatment MRI. RESULTS: The mean tumour volume was 12.79 ± 24.31 cm(3). Independent samples t test was significant for increasing overall all-cause survival and decreasing tumour volume (1 year: p = 0.003; 5-year: p = 0.031). Cox regression was significant for stratified tumour volume, nodal involvement and peri-neural invasion for predicting disease-free survival. CONCLUSIONS: MRI measured tumour volume assessment appears to be a reliable predictor of survival in patients with maxillary complex SCC treated by surgical resection.

Magnetic resonance imaging-based tumor volume measurements predict outcome in patients with squamous cell carcinoma of the mandible.

OBJECTIVE: The objectives of this study were to determine the benefit of pretreatment magnetic resonance imaging (MRI)-based tumor volume (Tv) measurements in patients presenting with squamous cell carcinomas (SCCs) involving the oral cavity subsites most frequently associated with mandibular bone invasion. STUDY DESIGN: A 10-year retrospective study of all patients undergoing surgical resection for primary SCC of the retromolar trigone, mandible, or floor of mouth (with bone involvement) was completed. In total, 62 patients met the inclusion criteria, and Tv measurements completed on their pretreatment MRI. RESULTS: Tumor volume was significant at predicting all-cause survival and disease-free survival at 5 years. Tv stratification to correlate with the TNM staging system resulted in down-staging in 40 of the 62 cases. CONCLUSIONS: Tumor volume was a more useful predictor of outcome than the current clinical or pathologic TNM staging, considering the automatic up-staging of tumors involving mandibular bone to T4 tumors.

Low molecular weight heparin in patients undergoing free tissue transfer following head and neck ablative surgery: review of efficacy and associated complications.

Most microsurgeons report the use of anticoagulants in their routine practice. Anti-Xa concentrations are preferentially used to monitor treatment with low molecular weight heparin (LMWH). The aim of this retrospective study was to measure the therapeutic response to standard dosing with LMWH (using anti-Xa) in patients after ablative and reconstructive surgery for head and neck cancer, and to review the associated risk of bleeding. We retrospectively reviewed 153 patients who had undergone resection of primary or recurrent tumours of the head and neck with free flap reconstruction. In total, 173 free flap procedures were completed. Medical records were reviewed to find the anticoagulation regimen used, anti-Xa result, patients' weight, and any associated complications. Fourteen patients returned to theatre because of bleeding; of these no cause was identified in 6 and a haematoma was evacuated. The distribution of unexplained haematoma was similar for all dose regimens of dalteparin. Anti-Xa results were available in 47 cases, and of these, 22 (47%) were within the prophylactic range (0.2 IU/ml or more). Our results highlight the high incidence of inadequate response to standard prophylactic doses of LMWH in patients with head and neck cancer. Increasing the dose of dalteparin does not seem to increase the risk of bleeding or formation of a haematoma. These findings may be transferable to other surgical specialties.

The nasolabial approach: a potential alternative to the lip-splitting incision for maxillectomy.

First described by Weber and later modified by Fergusson, the Weber-Fergusson incision has undergone numerous modifications, but the fundamental approach to maxillectomy has largely remained the same. We report the potential benefit of a nasolabial incision for partial maxillectomy. The incision is hidden within the nasolabial fold and obviates the need for division of the upper lip, which may undergo atrophy and shortening after radiotherapy.

Epinephrine, norepinephrine, dobutamine, and dopexamine effects on free flap skin blood flow.

BACKGROUND: The optimal sympathomimetic drug to support blood pressure without adverse vasoconstriction of free flap circulation remains unknown. This study examined the effects of four agents (epinephrine, norepinephrine, dobutamine, and dopexamine) on free flaps following resection of head and neck cancer. METHODS: Twenty-four patients (25 data sets) were recruited into the study. Each patient received an infusion of the four drugs in a random order, with an intervening washout period between drugs, at four infusion rates. Continuous free flap skin blood flow monitoring was performed using laser Doppler velocimetry, with a second sensor on normal skin acting as a control. Global cardiovascular variables were monitored using the LiDCO Rapid Pulse Contour Analysis System (LiDCO Ltd., Cambridge, United Kingdom). RESULTS: Dose-dependent, increased free flap skin blood flow was observed with norepinephrine and dobutamine. Both dopexamine and epinephrine infusions decreased blood flow. Flap skin blood conductance decreased (vasoconstriction) with norepinephrine, but markedly less than in control tissue, so overall the flap skin blood flow increased with increasing arterial blood pressure. Dobutamine increased flap skin conductance, without significantly increasing blood pressure, and modestly increased flap blood flow. CONCLUSIONS: Both dobutamine and norepinephrine had beneficial effects on flap skin blood flow. The maximal improvement in flow occurred with norepinephrine, making it the optimal pressor to use in patients with hypotension after free flap surgery.

A review of post-operative feeding in patients undergoing resection and reconstruction for oral malignancy and presentation of a pre-operative scoring system.

Percutaneous endoscopic gastrostomy (PEG) and nasogastric tubes (NGT) are routine after resection and reconstruction of oral cancer. The selection of the most appropriate method of feeding can be challenging, as both methods carry morbidity. This makes correct selection paramount. The objectives of this retrospective review were to identify the benefits and complications of feeding with PEG and NGT in patients with oral malignancy. We retrospectively reviewed 144 patients who had undergone oral cancer resection and reconstruction, to compare PEG and NGT feeding and to identify the key factors that aid selection of the most appropriate feeding method. We used these factors to develop the Key to Appropriate Replacement Enteral Nutrition (KAREN) scoring system. One hundred and twenty of the 144 patients were managed with PEG, and of these, 9 used it for less than 28 days. The mean (range) duration of use was 13 (5-63) days, and 1.9 (1-5) tubes/patient were used. The KAREN scoring system assigned the correct method of feeding in 92% of cases. The scoring system requires prospective validation but could provide clinicians with a tool to assist in a sometimes difficult decision.

Angioleiomyoma of the hard palate: report of a case and review of the literature and magnetic resonance imaging findings of this rare entity.

Angioleiomyomas are benign solitary smooth muscle tumors originating in the tunica media of vessels. They are rarely encountered within the oral cavity, and the number of reported cases specifically involving the hard palate remains small. A 39-year-old man presented with a 2-cm painless swelling on the left anterior hard palate. The mass had been present for ≈ 5 years before presentation, during which time it had slowly enlarged. Magnetic resonance imaging (MRI) showed a uniform signal pattern with T1 signal intensity slightly higher than surrounding soft tissues and marked hyperintensity on T2-weighted sequences. Although the MRI characteristics of angioleiomyomas affecting the extremities have previously been reported, this is the first reported case describing the MRI features of an oral-cavity angioleiomyoma. In view of the inability to differentiate angioleiomyoma from other pathologies with similar MRI features, simple local excision for definitive histopathologic diagnosis remains recommended.