Virtual tumor mapping and margin control with 3-D planning and navigation.

Computer technology-based treatment approaches like intraoperative navigation and intensity-modulated radiation therapy have become important components of state of the art head and neck cancer treatment. Multidirectional exchange of virtual three-dimensional patient data via an interdisciplinary platform allows all medical specialists involved in the patients treatment to take full advantage of these technologies. This review article gives an overview of current technologies and future directions regarding treatment approaches that are based on a virtual, three-dimensional patient specific dataset: storage and exchange of spatial information acquired via intraoperative navigation allow for a highly precise frozen section procedure. In the postoperative setting, virtual reconstruction of the tumor resection surface provides the basis for improved radiation therapy planning and virtual reconstruction of the tumor with integration of molecular findings creates a valuable tool for postoperative treatment and follow-up. These refinements of established treatment components and novel approaches have the potential to make a major contribution to improving the outcome in head and neck cancer patients.

Dimensional accuracy and simulation-based optimization of polyolefins and biocopolyesters for extrusion-based additive manufacturing and steam sterilization.

Polyolefins exhibit robust mechanical and chemical properties and can be applied in the medical field, e.g. for the manufacturing of dentures. Despite their wide range of applications, they are rarely used in extrusion-based printing due to their warpage tendency. The aim of this study was to investigate and reduce the warpage of polyolefins compared to commonly used filaments after additive manufacturing (AM) and sterilization using finite element simulation. Three types of filaments were investigated: a medical-grade polypropylene (PP), a glass-fiber reinforced polypropylene (PP-GF), and a biocopolyester (BE) filament, and they were compared to an acrylic resin (AR) for material jetting. Square specimens, standardized samples prone to warpage, and denture bases (n = 10 of each group), as clinically relevant and anatomically shaped reference, were digitized after AM and steam sterilization (134 °C). To determine warpage, the volume underneath the square specimens was calculated, while the deviations of the denture bases from the printing file were measured using root mean square (RMS) values. To reduce the warpage of the PP denture base, a simulation of the printing file based on thermomechanical calculations was performed. Statistical analysis was conducted using the Kruskal-Wallis test, followed by Dunn's test for multiple comparisons. The results showed that PP exhibited the greatest warpage of the square specimens after AM, while PP-GF, BE, and AR showed minimal warpage before sterilization. However, warpage increased for PP-GF, BE and AR during sterilization, whereas PP remained more stable. After AM, denture bases made of PP showed the highest warpage. Through simulation-based optimization, warpage of the PP denture base was successfully reduced by 25%. In contrast to the reference materials, PP demonstrated greater dimensional stability during sterilization, making it a potential alternative for medical applications. Nevertheless, reducing warpage during the cooling process after AM remains necessary, and simulation-based optimization holds promise in addressing this issue.

AI-Based Detection of Oral Squamous Cell Carcinoma with Raman Histology.

Stimulated Raman Histology (SRH) employs the stimulated Raman scattering (SRS) of photons at biomolecules in tissue samples to generate histological images. Subsequent pathological analysis allows for an intraoperative evaluation without the need for sectioning and staining. The objective of this study was to investigate a deep learning-based classification of oral squamous cell carcinoma (OSCC) and the sub-classification of non-malignant tissue types, as well as to compare the performances of the classifier between SRS and SRH images. Raman shifts were measured at wavenumbers k1 = 2845 cm-1 and k2 = 2930 cm-1. SRS images were transformed into SRH images resembling traditional H&E-stained frozen sections. The annotation of 6 tissue types was performed on images obtained from 80 tissue samples from eight OSCC patients. A VGG19-based convolutional neural network was then trained on 64 SRS images (and corresponding SRH images) and tested on 16. A balanced accuracy of 0.90 (0.87 for SRH images) and F1-scores of 0.91 (0.91 for SRH) for stroma, 0.98 (0.96 for SRH) for adipose tissue, 0.90 (0.87 for SRH) for squamous epithelium, 0.92 (0.76 for SRH) for muscle, 0.87 (0.90 for SRH) for glandular tissue, and 0.88 (0.87 for SRH) for tumor were achieved. The results of this study demonstrate the suitability of deep learning for the intraoperative identification of tissue types directly on SRS and SRH images.

Stimulated Raman histology for histological evaluation of oral squamous cell carcinoma.

OBJECTIVES: To investigate whether in patients undergoing surgery for oral squamous cell carcinoma, stimulated Raman histology (SRH), in comparison with H&E-stained frozen sections, can provide accurate diagnoses regarding neoplastic tissue and sub-classification of non-neoplastic tissues. MATERIALS AND METHODS: SRH, a technology based on Raman scattering, was applied to generate digital histopathologic images of 80 tissue samples obtained from 8 oral squamous cell carcinoma (OSCC) patients. Conventional H&E-stained frozen sections were then obtained from all 80 samples. All images/sections (SRH and H&E) were analyzed for squamous cell carcinoma, normal mucosa, connective tissue, muscle tissue, adipose tissue, salivary gland tissue, lymphatic tissue, and inflammatory cells. Agreement between SRH and H&E was evaluated by calculating Cohen's kappa. Accuracy of SRH compared to H&E was quantified by calculating sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) as well as area under the receiver operating characteristic curve (AUC). RESULTS: Thirty-six of 80 samples were classified as OSCC by H&E-based diagnosis. Regarding the differentiation between neoplastic and non-neoplastic tissue, high agreement between H&E and SRH (kappa: 0.880) and high accuracy of SRH (sensitivity: 100%; specificity: 90.91%; PPV: 90.00%, NPV: 100%; AUC: 0.954) were demonstrated. For sub-classification of non-neoplastic tissues, SRH performance was dependent on the type of tissue, with high agreement and accuracy for normal mucosa, muscle tissue, and salivary glands. CONCLUSION: SRH provides high accuracy in discriminating neoplastic and non-neoplastic tissues. Regarding sub-classification of non-neoplastic tissues in OSCC patients, accuracy varies depending on the type of tissue examined. CLINICAL RELEVANCE: This study demonstrates the potential of SRH for intraoperative imaging of fresh, unprocessed tissue specimens from OSCC patients without the need for sectioning or staining.

Analysis of the accuracy of computer-assisted DCIA flap mandibular reconstruction applying a novel approach based on geometric morphometrics.

BACKGROUND: This study evaluated the accuracy of computer-assisted surgery (CAS)-driven DCIA (deep circumflex iliac artery) flap mandibular reconstruction by traditional morphometric methods and geometric morphometric methods (GMM). METHODS: Reconstruction accuracy was evaluated by measuring distances and angles between bilateral anatomical landmarks. Additionally, the average length of displacements vectors between landmarks was computed to evaluate factors assumed to influence reconstruction accuracy. Principal component analysis (PCA) was applied to unveil main modes of dislocation. RESULTS: High reconstruction accuracy could be demonstrated for a sample consisting of 26 patients. The effect of the number of segments and length of defect on reconstruction accuracy were close to the commonly used significance threshold (p = 0.062/0.060). PCA demonstrated displacement to result mainly from sagittal and transversal shifts. CONCLUSIONS: CAS is a viable approach to achieve high accuracy in mandibular reconstruction and GMM can facilitate the evaluation of factors influencing reconstruction accuracy and unveil main modes of dislocation in this context.

Risk Factors for Prolonged Mechanical Ventilation and Delayed Extubation Following Bimaxillary Orthognathic Surgery: A Single-Center Retrospective Cohort Study.

BACKGROUND: Bimaxillary orthognathic surgery bears the risk of severe postoperative airway complications. There are no clear recommendations for immediate postoperative follow-up and monitoring. OBJECTIVE: to identify potential risk factors for prolonged mechanical ventilation and delayed extubation in patients undergoing bimaxillary orthognathic surgery. METHODS: The data of all consecutive patients undergoing bimaxillary surgery between May 2012 and October 2019 were analyzed in a single-center retrospective cohort study. The clinical data were evaluated regarding baseline characteristics and potential factors linked with delayed extubation. RESULTS: A total of 195 patients were included; 54.9% were female, and the median age was 23 years (IQR 5). The median body mass index was 23.1 (IQR 8). Nine patients (4.6%) were of American Society of Anesthesiologists Physical Status Classification System III or higher. The median duration of mechanical ventilation in the intensive care unit was 280 min (IQR, 526 min). Multivariable analysis revealed that premedication with benzodiazepines (odds ratio (OR) 2.60, 95% confidence interval (0.99; 6.81)), the male sex (OR 2.43, 95% confidence interval (1.10; 5.36)), and the duration of surgery (OR 1.54, 95% confidence interval (1.07; 2.23)) were associated with prolonged mechanical ventilation. By contrast, total intravenous anesthesia was associated with shorter ventilation time (OR 0.19, 95% confidence interval (0.09; 0.43)). CONCLUSION: premedication with benzodiazepines, the male sex, and the duration of surgery might be considered to be independent risk factors for delayed extubation in patients undergoing bimaxillary surgery.

The Role of von Willebrand Factor in Microvascular Surgery in Severely Injured Patients.

Microvascular anastomosis has become a standard surgical technique for reconstruction because of increasing possibilities, indications, and clinical success regarding the survival of the flaps. However, the main dreaded complications exist in thrombosis. Leaving surgical complications aside, systemic problems like disorder of the coagulation-fibrinolysis system are a significant cause of graft loss usually being unrecognized. Reports exist describing a hypercoagulable state with clotting activation and inhibition of fibrinolysis after trauma and delayed surgery considering the secondary homeostasis. In this clinical case, a patient had a large soft tissue defect at the temporal side of the head after severe trauma. After some days of primary stabilization, reconstruction using a free microvascular latissimus dorsi flap was performed. Multiple revisions of the arterial and venous branches had to be performed intraoperatively due to insufficient flap perfusion. After 24 hours, definitive flap loss occurred due to multiple thrombosis in the arterial and venous branches. Postoperative comprehensive coagulation analysis revealed a distinct activation of primary hemostasis with massively increased von Willebrand factor parameters and factor VIII activity as well as acetylsalicylic acid resistance contributing to thrombotic occlusion. In severely injured patients, comprehensive preoperative determination of the coagulation status (especially those of the primary hemostasis) is indispensable before performing free flap reconstruction surgeries to reduce the risk of microvascular flap loss.

Microvascular transplants in head and neck reconstruction: 3D evaluation of volume loss.

BACKGROUND: Despite oversized latissimus dorsi free flap reconstruction in the head and neck area, esthetic and functional problems continue to exist due to the well-known occurrence of transplant shrinkage. The purpose of this study was to acquire an estimation of the volume and time of the shrinkage process. MATERIALS AND METHODS: The assessment of volume loss was performed using a 3D evaluation of two postoperative CT scans. A retrospective review was conducted on all latissimus dorsi free flap reconstructions performed between 2004 and 2013. Inclusion criteria for the assessment were: resection of an oral carcinoma and microsurgical defect coverage with latissimus dorsi free flap; a first postoperative CT (CT1) performed between 3 weeks and a maximum of 3 months after reconstruction surgery; and an additional CT scan (CT2) performed at least one year postoperatively. The exclusion criterion was surgical intervention in the local area between the acquisition of CT1 and CT2. The effect of adjuvant radiation therapy was considered. Volume determination of the transplant was carried out in CT1 and CT2 by manual segmentation of the graft. RESULTS: Fifteen patients were recruited. 3D evaluation showed an average volume loss of 34.4%. In the consideration of postoperative radiotherapy the volume reduction was 39.2% in patients with radiotherapy and 31.3% in patients without radiotherapy. CONCLUSION: The reconstruction flap volume required for overcorrection of the surgical defect was investigated. This study indicates that a volume loss of more than 30% could be expected one or more years after latissimus dorsi free flap reconstruction. Clinical trial number DRKS00007534.

The validity of surgical clips as radiographic markers for the tumour resection cavity in head and neck cancer treatment.

BACKGROUND: A prerequisite of irradiation after advanced head and neck tumour resection is the accurate localization of the tumour resection margin. The purpose of the following study is to evaluate the use of surgical clips placed in the tumour resection margins for use as radiographic markers to facilitate focussed adjuvant radiation therapy. MATERIALS: To evaluate whether the clips remain predictive for the resection margin, we analysed the deviation of each clip in two postoperative CT scans on different days. Bone registration points were used to fuse the two CT scans in the region of the primary tumour and the distances between corresponding clips were measured. RESULTS: The tumour resection margins were labelled with an average of 18 titanium clips. In total 282 clips were evaluated. Metric analysis of clip deviation between the two postoperative CT scans found a mean distance of 4.5 mm ± 2.5 mm with a range of 0.5-11.8 mm. No significant statistical relationship of the clip differences as a function of time, the method of reconstruction or administered radiotherapy could be demonstrated. CONCLUSION: Placement of surgical clips in the cavity walls after complete tumour resection provides an easy and inexpensive approach for defining resection margins and allows for increased accuracy of adjuvant treatment. Clinical trial number DRKS00007534.

Clipping of tumour resection margins allows accurate target volume delineation in head and neck cancer adjuvant radiation therapy.

BACKGROUND: Accurate tumour bed localisation is a key requirement for adjuvant radiotherapy. A new procedure is described for head and neck cancer treatment that improves tumour bed localisation using titanium clips. MATERIALS AND METHODS: Following complete local excision of the primary tumour, the tumour bed was marked with titanium clips. Preoperative gross target volume (GTV) and postoperative tumour bed were examined and the distances between the centres of gravity were evaluated. RESULTS: 49 patients with squamous cell carcinoma of the oral cavity were prospectively enrolled in this study. All patients underwent tumour resection, neck lymph node dissection and defect reconstruction in one stage. During surgery, 7-49 clips were placed in the resection cavity. Surgical clip insertion was successful in 88% (n=43). Clip identification and tumour bed delineation was successful in all 43 patients. The overall distance between the centres of gravity of the preoperative tumour extension to the tumour bed was 0.9cm. A significant relationship between the preoperative tumour extension and the postoperative tumour bed volume could be demonstrated. CONCLUSION: We demonstrate a precise delineation of the former tumour cavity. Improvements in tumour bed delineation allow an increase of accuracy for adjuvant treatment.

Marking of tumor resection borders for improved radiation planning facilitates reduction of radiation dose to free flap reconstruction in head and neck cancer surgery.

Accurate localization of tumor resection borders is crucial for adjuvant radiotherapy. An improvement to adjuvant radiotherapy with the reduction of radiation doses to free flap reconstruction by virtual navigation procedures and titanium clips was evaluated. Thirty-three patients with oral cancer were prospectively included in the study. Following complete local excision of the primary tumor, resection borders were marked virtually using a navigation pointer and with titanium ligature clips. Postoperative delineation of tumor resection borders was examined. In five patients with microvascular free flap reconstruction a reduction of the radiation dose to the free flap reconstruction was achieved. The tumor resection borders in 30 patients were marked with titanium ligature clips. Surgical clip insertion was successful in 91%. We demonstrate a significant relationship between the reconstruction volume and the part of the target volume which will receive a reduced radiation dose. A cumulative dose of 60 Gy was administered to the target volume and a significant reduction of the administered radiation dose to the center of the flap could be demonstrated. We demonstrate an accurate delineation of the tumor resection margins. These improvements in tumor resection margin delineation allow for increased accuracy in adjuvant treatment and a reduction of radiation dose to the vascular free flap reconstruction.

Preformed vs intraoperative bending of titanium mesh for orbital reconstruction.

OBJECTIVE: The most accurate orbital reconstructions result from an anatomic repair of the premorbid orbital architecture. Many different techniques and materials have been used; unfortunately, there is currently no optimal method. This study compares the use of preformed vs intraoperative bending of titanium mesh for orbital reconstruction in 2-wall orbital fractures. STUDY DESIGN: Cadaver-based study. SETTING: University hospital. SUBJECTS AND METHODS: Preinjury computed tomography scans were obtained in 15 cadaveric heads (30 orbits). Stereolithographic (STL) models were fabricated for 5 of the specimens (10 orbits). Two wall fractures (lamina papyracea and floor) were then generated in all orbits. Surgical reconstruction was performed in all orbits using 1 of 3 techniques (10 orbits each): (1) patient-specific implant molded from the preinjury STL model, (2) titanium mesh sheet bent freehand, and (3) preformed titanium mesh. Each technique was evaluated for orbital volume correction, contour accuracy, ease of use, and cost. RESULTS: No difference in volume restoration was found between the 3 techniques. Patient-specific implants had the greatest contour accuracy, poor ease of use, and highest cost. Freehand bending implants had the poorest contour accuracy, acceptable ease of use, and lowest cost. Preformed mesh implants had intermediate contour accuracy, excellent ease of use, and low cost. CONCLUSION: All 3 techniques provide equivalent orbital volume correction. However, preformed mesh implants have many advantages based on contour accuracy, ease of use, and relative cost.

Qualitative and quantitative evaluation of bony structures based on DICOM dataset.

PURPOSE: The aim of this study was to investigate bone mass using different cone-beam computed tomographies (CBCTs) combined with image analysis and to determine whether bone quantity or quality was detected. MATERIALS AND METHODS: Different measurements recorded on mandible bones of pigs in the retromolar region were evaluated on ProMax 3D (Planmeca Oy, Finland) and the ILUMA™CT (IMTEC™ Imaging, Ardmore, OK) to calculate a calibration curve. The spatial relationships of pig mandible halves relative to adjacent defined anatomical structures were assessed by means of 3D visualization software. In addition to the screenshot, their bone quality was evaluated in accordance with the Lenkholm and Zarb classification. RESULTS: The CBCT calibration curves based on the measurements taken from the ProMax and ILUMA CT showed linear correlation. Huge Hounsfield units intervals were found between the 2 CBCTs and there was no correlation with the computed tomography. Exact information on the micromorphology of the bone cylinders was not available. A subjective correlation according to Lenkholm and Zarb showed overlapping in all groups. CONCLUSIONS: CBCT is a good choice for analyzing bone mass. However, it does not provide any information on bone quality. To obtain information on the microarchitecture of the spongiosa, it is necessary to use a computed tomography with finite element analysis.

Anatomical shape analysis of the mandible in Caucasian and Chinese for the production of preformed mandible reconstruction plates.

PURPOSE: The purpose of this study was to evaluate and analyze statistical shapes of the outer mandible contour of Caucasian and Chinese people, offering data for the production of preformed mandible reconstruction plates. METHODS: A CT-database of 925 Caucasians (male: n=463, female: n=462) and 960 Chinese (male: n=469, female: n=491) including scans of unaffected mandibles were used and imported into the 3D modeling software Voxim (IVS-Solutions, Chemnitz, Germany). Anatomical landmarks (n=22 points for both sides) were set using the 3D view along the outer contour of the mandible at the area where reconstruction plates are commonly located. We used morphometric methods for statistical shape analysis. RESULTS: We found statistical relevant differences between populations including a distinct discrimination given by the landmarks at the mandible. After generating a metric model this shape information which separated the populations appeared to be of no clinical relevance. The metric size information given by ramus length however provided a profound base for the production of standard reconstruction plates. CONCLUSION: Clustering by ramus length into three sizes and calculating means of these size-clusters seem to be a good solution for constructing preformed reconstruction plates that will fit a vast majority.

Influence of different registration modalities on navigation accuracy in ear, nose, and throat surgery depending on the surgical field.

OBJECTIVES/HYPOTHESIS: Various invasive and noninvasive registration methods have been established in the past for intraoperative navigation. The present study compared the registration and navigation accuracy of three different registration modalities in anatomical locations of special interest for ear, nose, and throat surgery. STUDY DESIGN: Prospective experimental phantom study. METHODS: Four skull models were individually fabricated with a three-dimensional printer based on the patient's computed tomography data sets and fitted with an individual customized silicone skin. Three different registration modalities were examined: 1) invasive marker (IM), 2) oral splint (OS), and 3) laser scan (L). Accuracy measurements were assessed by targeting 26 titanium screws placed over the skull. The overall accuracy and the target registration error for eight selected anatomical locations were measured. RESULTS: Mean accuracy was 0.67 + or - 0.1 mm (quadratic mean + or - standard deviation) for IM, 0.98 + or - 0.16 mm for OS, and 1.3 + or - 0.12 mm for L. The greatest differences in accuracy were found on the mastoid with best accuracy for IM (0.59 + or - 0.2 mm; P < .05 vs. OS and L), followed by OS (1.23 + or - 0.41 mm; P < .05 vs. L), and L (1.88 + or - 0.45 mm). In contrast, only small differences in accuracy were detected in the anterior skull base between the registration modalities (IM 0.75 + or - 0.21 mm, OS 0.71 + or - 0.27 mm, L 0.93 + or - 0.34 mm). CONCLUSIONS: L and OS meet accuracy requirements in the midface and anterior skull base. OS is superior to L with navigation accuracies comparable to marker registration. However, neither method meets the high precision requirements for lateral skull base surgery. Laryngoscope, 2010.

Bone treatment laser-navigated surgery.

A new concept was developed based on the experience gained in dental rehabilitation with implantation in the oral maxillofacial region. Despite the use of cooling systems, mechanically rotating instruments may damage the surrounding tissue due to the frictional heat generated. An alternative approach for bone removal is laser application. A preoperative plan was prepared. Laser ablation was performed in accordance with the data set on bovine bone using a navigation system. This new concept allows precise bone removal and adjustment of the laser power according to the preoperative plan. The power of the laser automatically decreases as it approaches the border of the planned cavity or important anatomical structures. The advantage of this approach is precise and safe bone removal without damaging the bone by frictional heat.

Osteomyelitis of the mandible following third molar surgery: a regrettable consequence in a healthy patient.

This clinical case describes mandibular osteomyelitis in a healthy 31-year-old man as a severe complication following third molar removal. Recurrent abscess formations were treated with intensive therapy involving antibiotics, surgical debridement of the affected region, and hyperbaric oxygen. In the follow-up, despite microbiologic study to determine the indicated treatment approach, a severe osteomyelitis was present, clinically and radiographically. Finally, a partial resection of the mandible, including exarticulation, was indicated to manage this severe complication.

Report of rare bilateral nasolabial cysts.

PURPOSE: Nasolabial cysts are usually unilateral and are quite rare, while bilateral cysts are even rarer. PATIENT AND METHOD: Our report concerns a 48-year-old female with bilateral nasolabial cysts. After many years of misdiagnosis she was finally referred to our clinic with a subnasal swelling of unknown origin. RESULT: Evaluation of the patient's medical history, clinical examination and of a previous CT scan led to the diagnosis of a nasolabial cyst, which was later confirmed by histological examination. Treatment involved the surgical excision. CONCLUSION: A complete surgical excision is recommended using a sublabial approach as the treatment of choice, although transnasal endoscopic marsupialization seems to be a simple and effective alternative. It has been shown that after successful marsupialization, the nasolabial cyst is converted to an air-containing paranasal sinus.

Sensitivity and specificity of oral brush biopsy.

The aim of this study was to evaluate the advantage of computer-assisted analysis of the oral brush biopsy compared with synchronous scalpel biopsy in the early detection of oral lesions. In this prospective, randomized, controlled study, brush and scalpel biopsies were performed on 75 patients. Six patients had to be excluded due to inadequate results, and 43 were shown to have dysplastic epithelium, 15 carcinoma, and 11 suspicious lesions. Therefore, the sensitivity for the detection of abnormal cells by means of OralCDx was 52%, specificity 29%, and the positive predictive value 63%. According to our results, the use of oral brush biopsy as a standardized, minimally invasive method of screening oral lesions should be reconsidered.