F-18 Positron Emission Tomography and Computed Tomography Image-Fusion for Image-Guided Detection of Local Recurrence in Patients With Head and Neck Cancer Using a 3-Dimensional Navigation System: A Preliminary Report

Factors influencing the accuracy of multimodal image fusion for oral and maxillofacial tumors: a retrospective study

BACKGROUND

Ensuring high accuracy in multimodal image fusion for oral and maxillofacial tumors is crucial before further application. The aim of this study was to explore the factors influencing the accuracy of multimodal image fusion for oral and maxillofacial tumors.

METHODS

Pairs of single-modality images were obtained from oral and maxillofacial tumor patients, and were fused using a proprietary navigation system by using three algorithms (automatic fusion, manual fusion, and registration point-based fusion). Fusion accuracy was evaluated including two aspects-overall fusion accuracy and tumor volume fusion accuracy-and were indicated by mean deviation and fusion index, respectively. Image modality, fusion algorithm, and other characteristics of multimodal images that may have potential influence on fusion accuracy were recorded. Univariate and multivariate analysis were used to identify relevant affecting factors.

RESULTS

Ninety-three multimodal images were generated by fusing 31 pairs of single-modality images. The interaction effect of image modality and fusion algorithm (P = 0.02, P = 0.003) and thinner slice thickness (P = 0.006) were shown to significantly influence the overall fusion accuracy. The tumor volume (P < 0.001), tumor location (P = 0.007), and image modality (P = 0.01) were significant influencing factors for tumor volume fusion accuracy.

CONCLUSIONS

To ensure high overall fusion accuracy, manual fusion was not preferred in CT/MRI image fusion, and neither was automatic fusion in image fusion containing PET modality. Using image sets with thinner slice thickness could increase overall fusion accuracy. CT/MRI fusion yielded higher tumor volume fusion accuracy than fusion containing PET modality. The tumor volume fusion accuracy should be taken into consideration during image fusion when the tumor volume is small and the tumor is located in the mandible.

Accuracy of multimodal image fusion for oral and maxillofacial tumors: A revised evaluation method and its application

OBJECTIVE

To develop a revised evaluation method for accuracy of multimodal image fusion for oral and maxillofacial tumors and explore its application for comparing the accuracy of three commonly used fusion algorithms, automatic fusion, manual fusion, and registration point-based fusion.

MATERIALS AND METHODS

Image sets of patients with oral and maxillofacial tumor were fused using the iPlan 3.0 navigation system. Fusion accuracy included two aspects: (1) overall fusion accuracy: represented by the mean value of the coordinate differences along the x-, y-, and z- axes (Δx, Δy, and Δz), mean deviation (MD), and root mean square (RMS) of six pairs of landmarks on the two image sets; (2) tumor volume fusion accuracy: represented by Fusion Index (FI), which was calculated based on the volume of tumor delineated on the two image sets.

RESULTS

Eighteen pairs of image sets of 17 patients were enrolled in this study. The Δx and Δy values for the three algorithms were less than 1.5 mm. The Δz values for automatic fusion, manual fusion and registration point-based fusion was 1.049 mm, 1.864 mm and 1.254 mm. The MD for automatic fusion, manual fusion and registration point-based fusion was 1.978 mm, 2.788 mm and 1.926 mm. Significant differences existed in Δz for manual fusion and that for automatic fusion (P = 0.058), in MD for manual fusion and that for automatic fusion (P = 0.087), and in MD for manual fusion and that for registration point-based fusion (P = 0.069). The FI for automatic fusion, manual fusion, and registration point-based fusion was 0.594, 0.520, and 0.549; the inter-algorithm differences were not significant (P = 0.290).

CONCLUSION

The automatic fusion and the registration point-based fusion were more accurate than manual fusion, and therefore were recommended to be used in multimodal image fusion for oral and maxillofacial tumors.

Assessment of tumor margins in head and neck cancer using a 3D-navigation system based on PET/CT image-fusion - A pilot study

OBJECTIVES

Determination of tumor margins in patients with squamous cell carcinoma of the head and neck (SCCHN) is mostly based on preoperative magnetic resonance imaging (MRI) or computed tomography scans (CT). Local recurrence of disease is often correlated with the presence of positive resection margins after surgical treatment. Positron emission tomography/computed tomography (PET/CT) imaging plays a crucial role in the assessment of patients with SCCHN. The purpose of this study was to determine whether PET/CT could predict tumor extension.

METHODS

In 12 patients who underwent surgical treatment of primary SCCHN (Stage III-IV) F18-FDG PET/CT image-fusion was performed on a 3D navigation-system based workstation. Image-guided needle biopsies were obtained from four different, color-coded metabolic areas within the tumor. The histopathological findings were correlated with findings on corresponding PET/CT scans.

RESULTS

81.3% of biopsies from the central area were positive. Specimens taken from the outer metabolic zone were positive in 66.7% of the patients. The highest incidence of positive biopsies was found in the zone adjacent to the outermost area. There was a statistically significant difference in positive tumor histopathology when comparing the various metabolic zones (p = 0.03).

CONCLUSION

Exact determination of tumor is an important research topic, although results remain controversial. The results of this study suggest that in some cases PET scans may overestimate tumor extension.

Three-Dimensional Image Fusion of 18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography and Contrast-Enhanced Computed Tomography for Computer-Assisted Planning of Maxillectomy of Recurrent Maxillary Squamous Cell Carcinoma and Defect Reconstruction

PURPOSE

The purpose of this study was to describe new technology assisted by 3-dimensional (3D) image fusion of ¹⁸F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT (CECT) for computer planning of a maxillectomy of recurrent maxillary squamous cell carcinoma and defect reconstruction.

MATERIALS AND METHODS

Treatment of recurrent maxillary squamous cell carcinoma usually includes tumor resection and free flap reconstruction. FDG-PET/CT provided images of regions of abnormal glucose uptake and thus showed metabolic tumor volume to guide tumor resection. CECT data were used to create 3D reconstructed images of vessels to show the vascular diameters and locations, so that the most suitable vein and artery could be selected during anastomosis of the free flap. The data from preoperative maxillofacial CECT scans and FDG-PET/CT imaging were imported into the navigation system (iPlan 3.0; Brainlab, Feldkirchen, Germany). Three-dimensional image fusion between FDG-PET/CT and CECT was accomplished using Brainlab software according to the position of the 2 skulls simulated in the CECT image and PET/CT image, respectively. After verification of the image fusion accuracy, the 3D reconstruction images of the metabolic tumor, vessels, and other critical structures could be visualized within the same coordinate system. These sagittal, coronal, axial, and 3D reconstruction images were used to determine the virtual osteotomy sites and reconstruction plan, which was provided to the surgeon and used for surgical navigation.

RESULTS

The average shift of the 3D image fusion between FDG-PET/CT and CECT was less than 1 mm. This technique, by clearly showing the metabolic tumor volume and the most suitable vessels for anastomosis, facilitated resection and reconstruction of recurrent maxillary squamous cell carcinoma.

CONCLUSIONS

We used 3D image fusion of FDG-PET/CT and CECT to successfully accomplish resection and reconstruction of recurrent maxillary squamous cell carcinoma. This method has the potential to improve the clinical outcomes of these challenging procedures.

Minimal invasive biopsy of intraconal expansion by PET/CT/MRI image-guided navigation: a new method

Intraorbital tumours are often undetected for a long period and may lead to compression of the optic nerve and loss of vision. Although CT, MRI's and ultrasound can help in determining the probable diagnosis, most orbital tumours are only diagnosed by surgical biopsy. In intraconal lesions this may prove especially difficult as the expansions are situated next to sensitive anatomical structures (eye bulb, optic nerve). In search of a minimally invasive access to the intraconal region, we describe a method of a three-dimensional, image-guided biopsy of orbital tumours using a combined technique of hardware fusion between (18)F-FDG Positron Emission Tomography ((18)F-FDG PET), magnetic resonance imaging (MRI) and Computed Tomography (CT).

METHOD AND MATERIAL

We present 6 patients with a total of 7 intraorbital lesions, all of them suffering from diplopia and/or exophthalmos. There were 3 female and 3 male patients. The patients age ranged from 20 to 75 years. One of the patients showed beginning loss of vision. Another of the patients had lesions in both orbits. The decision to obtain image-guided needle biopsies for treatment planning was discussed and decided at an interdisciplinary board comprising other sub-specialities (ophthalmology, neurosurgery, maxillofacial surgery, ENT, plastic surgery). All patients underwent 3D imaging preoperatively ((18)F-FDG PET/CT or (18)F-FDG PET/CT plus MRI). Data was transferred to 3D navigation system. Access to the lesions was planned preoperatively on a workstation monitor. Biopsy-needles were then calibrated intraoperatively and all patients underwent three-dimensional image-guided needle biopsies under general anaesthesia.

RESULTS

7 biopsies were performed. The histologic subtype was idiopathic orbital inflammation in 2 lesions, lymphoma in 2, Merkel cell carcinoma in 1, hamartoma in 1 and 1 malignant melanoma. The different pathologies were subsequently treated in consideration of the actual state of the art. In cases where surgical removal of the lesion was performed the histological diagnosis was confirmed in all cases.

CONCLUSION

There is a wide range of possible treatment modalities for orbital tumours depending on the nature of the lesion. Histological diagnosis is mandatory to select the proper management and operation. The presented method allows minimal-invasive biopsy even in deep intraconal lesions, enabling the surgeon to spare critical anatomical structures. Vascular lesions such as cavernous haemangioma, tumour of the lacrimal gland or dermoid cysts present a contraindication and have to be excluded.

Navigation-assisted localisation and resection of subclinical metastatic malignant melanoma of unknown primary based on 18-fluorodeoxyglcose positron emission tomography computed tomography fusion imaging

A technical application using a stereotactic navigation system with fusion images of [18F]-2-fluorodeoxyglucose (FDG) positron tomography and computed tomography (PET-CT) in the case of a metastatic melanoma of unknown primary site is described. A 50-year-old woman presented with a slow, growing level V neck lump which was cytologically proved to be a metastatic melanoma despite the absence of prior or existing history of skin malignancy. Whilst detailed physical examination failed to yield the site of the primary lesion, full body FDG-PET images isolated FDG-avid subclinical scalp lesions. Fused PET-CT data provided the navigation system with accurate localisation of the subclinical metastatic lesion. Histopathological examination of the navigation-guided resection specimen confirmed that the lesion was excised with acceptable margins. This case illustrates the feasibility of navigation-assisted resection of a subclinical malignant melanoma lesion and may have a role to play in the management of the melanoma of unknown primary.

Computer-Aided Maxillofacial Surgery: An Update

Introduction. Recent developments in technology have revolutionized medicine and surgery. This article aims at providing an update on the current trends in computer-aided maxillofacial surgery and illustrates these advances with clinical cases. Methods. The PubMed database was searched for articles published during the past 5 years using the keywords “maxillofacial” and “surgery, computer-assisted.” Full texts of relevant articles were retrieved, and their study details were extracted. Results. Among the 133 articles, most focused on cone-beam computed tomography (CBCT), stereophotography, surgical panning software, and intraoperative navigation. Stereophotography produces 3D facial photographs with natural color and texture, whereas CBCT generates excellent hard-tissue images with a substantially lower radiation than conventional CT scans. Information gathered from CBCT and stereophotography can be used for accurate diagnosis, virtual planning, and simulation of surgery with the aid of specialized software. The preplanned treatment can be executed accurately via intraoperative surgical navigation. Conclusion. Tremendous potential exists for computer-aided maxillofacial surgery as it moves from research to clinical care.