"Black Bone" MRI: a potential non-ionizing method for three-dimensional cephalometric analysis--a preliminary feasibility study.

OBJECTIVES: CT offers a three-dimensional solution to the inaccuracies associated with lateral cephalogram-based cephalometric analysis. However, it is associated with significant concerns regarding ionizing radiation exposure. MRI offers a non-ionizing alternative, but this has been less well investigated. We present a novel gradient echo MRI sequence ("Black Bone") and highlight the potential of this sequence in cephalometric analysis. METHODS: After regional ethics approval, "Black Bone" imaging was obtained in eight patients in whom lateral cephalograms were available. "Black Bone", T1 and T2 weighted spin echo imaging were obtained in the mid-sagittal plane, and measurements were compared with those obtained on the lateral cephalogram using both the Advantage Windows Workstation (GE Medical Systems, Buckinghamshire, UK) and the Dolphin(®) cephalometric software (v. 11.5.04.23, Premium; Dolphin Imaging, Chatsworth, CA) by one assessor. Further assessment was made by scoring the ease of landmark identification on a ten-point scale. RESULTS: "Black Bone" imaging surpassed T1 and T2 weighted imaging in terms of cephalometric landmark identification. A number of mid-sagittal cephalometric landmarks could not be clearly identified on T2 weighted imaging, making analysis impossible. Measurements on "Black Bone" demonstrated the smallest discrepancy when compared with those obtained on the lateral cephalogram. The discrepancy seen between measurements completed on mid-sagittal MRI and the lateral cephalogram was compounded by inherent inaccuracies of the lateral cephalogram. The overall mean discrepancy between distance measurements on "Black Bone" imaging and those on the lateral cephalogram was 1-2 mm. CONCLUSIONS: Overall, "Black Bone" MRI offered an improved method of cephalometric landmark identification over routine MRI sequences, and provides a potential non-ionizing alternative to CT for three-dimensional cephalometrics.

Automatic upstaging of tongue squamous cell carcinoma with lateral extrinsic muscle involvement is not justified.

The TNM classification for oral malignancies has been criticized for its upstaging to T4a when tumour involves styloglossus, hyoglossus, palatoglossus and genioglossus. The aims of this study were to (1) create an anatomical computer atlas of extrinsic tongue musculature, and (2) reassess the original staging of pre-treatment archived magnetic resonance images (MRI) of tongue carcinomas using the strict extrinsic muscle criteria. The anatomy of the extrinsic tongue muscles was mapped using images from the Visible Human Project (VHP) to create a computer model of the extrinsic tongue muscles. This was co-registered with 87 archived pre-staging MRI scans of tongue carcinomas to assess tumour ingress of the extrinsic tongue muscles. Of the 87 image sets reviewed, 16 were of superficial tumours not visible on MRI. In the remaining 71 cases that showed positive extrinsic muscle tumour ingress, 52% were upstaged from T1/2/3 tumours to cT4a based upon this finding. Extrinsic lateral and genioglossus muscle invasion did not predict occult cervical lymph node invasion or disease-related survival. In conclusion, tumour invasion of styloglossus or hyoglossus would result in the majority of lateral tongue tumours being staged T4a. Such stratification is of little clinical relevance, and an alternative more reliable method is required.

"Black bone" MRI: a potential alternative to CT when imaging the head and neck: report of eight clinical cases and review of the Oxford experience.

OBJECTIVE: The potential risks associated with ionising radiation are well documented. We have previously reported the "black bone" MRI sequence, useful when imaging cortical bone. The objective of this paper is to report our initial experience of this technique in patients undergoing imaging of the head and neck region. METHODS: Using the departmental database those patients having had "black bone" sequences of the head and neck performed as part of their MRI examination in the preceding 5 years were identified. The radiological reports were reviewed to identify those cases where "black bone" or conventional MRI sequences had been performed in place of the requested CT, and the patient medical records for these cases were reviewed. Medical record review was also conducted for those cases where it was considered that the pathological condition requiring imaging would ordinarily be investigated with CT. RESULTS: The "black bone" sequence had been performed in 69 patients as part of routine MRI of the head and neck. Of these, 67% (n=46) were performed in combination with CT imaging, the majority of cases being primary tumours. In four cases, an MRI was performed in place of the requested CT scan. We present eight clinical cases illustrating the potential benefits of the "black bone" sequence. CONCLUSIONS: "Black bone" MRI offers a radiation-free method of imaging the head and neck, and has been successfully utilised in a range of benign and malignant conditions affecting this region. Advances in knowledge Adoption of this approach, where feasible, would be a significant advance in radiation protection.

"Black bone" MRI: a partial flip angle technique for radiation reduction in craniofacial imaging.

The potential harmful effects of ionising radiation continue to be highlighted. Radiation reduction techniques have largely consisted of low-dose techniques rather than a shift to non-ionising methods of imaging. CT scanning is frequently employed for imaging the craniofacial skeleton despite being one of the key anatomical regions for radiation protection in view of the radiosensitive lens and thyroid gland. We describe a low flip angle gradient echo MRI sequence which provides high image contrast between bone and other tissues but reduces the contrast between individual soft tissues. This permits the "black bone" to be easily distinguished from the uniformity of the soft tissues. While maintaining a repetition time of 8.6 ms and an echo time of 4.2 ms, the flip angle which provided optimised suppression of both fat and water was identified to be 5°. The biometric accuracy of this sequence was confirmed using a phantom to obtain direct anatomical measurements and comparable CT scanning. The average discrepancy between black bone MRI measurements and direct anatomical measurements was 0.32 mm. Black bone MRI therefore has the potential to reduce radiation exposure by replacing CT scanning when imaging the facial skeleton, with particular scope for imaging benign conditions in the young.

Evaluating lingual carcinoma for surgical management: what does volumetric measurement with MRI offer?

MRI plays a crucial but under utilized role in the surgical management of lingual squamous cell carcinoma (SCC). Measurement of three-dimensional tumour volume (TV) has the potential to guide management of clinically negative cervical lymph nodes and address deficiencies in current TNM staging criteria This work studied the value of MRI-measured TV as a predictor of 2 year disease-related survival (DRS) and disease-free survival (DFS), as well as occult cervical lymph node metastasis (OM) in lingual cancer. TV was determined by manually segmenting the tumour contour in each image slice and using the resulting pixel value to calculate the three-dimensional extent of disease. TV was also compared with the more established measure of tumour thickness (TT) Significant differences in DRS (χ²(1) = 7.7, Hazard ratio (HR) = 7.3, p = 0.005) and DFS (χ²(1) = 5.6, HR = 4.3, p = 0.02) at two years were found using a cut-off of 8 cm³. Similarly, a significant relationship between TV and occult cervical lymph node metastasis was discovered using a 3 cm³ cut-off (OR = 6.7, p = 0.02, Fisher's Exact Test).

Alveolar soft-part sarcoma of the tongue: report of a case and review of the literature.

Alveolar soft part sarcoma (ASPS) accounts for less than 1% of all sarcomas. More frequently encountered within the lower limbs, the authors present a 24-year-old male with ASPS presenting as an asymptomatic swelling of the lateral tongue. At 12 months post wide local excision of the lesion, the patient remains well with no evidence of local or regional recurrence. Histological and immunohistochemical features are diagnostic of ASPS. Whilst rare, head and neck surgeons should be aware of ASPS as a potential cause of slow growing lesions, as early surgical resection is vital in view of the propensity for metastatic spread.

A comparative study of evaluation of radiographs, CT and 3D reformatted CT in facial trauma: what is the role of 3D?

A panel of 17 trainee maxillofacial surgeons viewed 23 cases of facial trauma, demonstrated on radiographs, axial CT images and three-dimensional (3D) reformatted CT images in a standardized viewing format under standard conditions. Their diagnostic interpretation, extraction of information relevant to surgical management and subjective evaluation of each modality were recorded by standard questionnaire and compared with a gold standard evaluation by a consultant radiologist and surgeon reading based on results of clinical management. There were clear and measurable differences in the viewers' evaluations of radiographs, CT and 3D reformatted images. Overall, surgeons showed more accurate diagnostic reading of radiographs and 3D reformatted images. This was in contrast to their subjective assessment of the clinical value of each modality, which showed a strong preference for 3D over all other techniques and for CT over radiographs. However the perceived benefit of axial CT images over radiographs was not reproduced on objective testing in this group; surgeons appear to perform less well in interpreting CT images than their subjective response to the modality would suggest. This work has supported the view that surgeons value 3D imaging as a front-line tool in the evaluation and management of selected cases of acute facial trauma. We have demonstrated that the perceived benefits of 3D reformatted CT to surgeons appear real.

Reconstruction of the temporomandibular joint by the transfer of the free vascularised second metatarsal.

We present our experience of a series of patients who presented for salvage reconstruction of the temporomandibular joint (TMJ) for relief of pain. Reconstruction was achieved by transfer of the free vascularised second metatarsal. This technique has been used for a total of seven TMJ reconstructions in five patients. We describe the surgical anatomy, technique and results during the last 18 years. One joint failed but the other six surviving joints continue to provide adequate pain-free function. We advocate this technique for autogenous salvage reconstruction in joints that have been previously operated on unsuccessfully.

Cellular mechanisms of osteoclast formation and lacunar resorption in giant cell granuloma of the jaw.

BACKGROUND: Giant cell granuloma (GCG) is an osteolytic tumour of the jaw which is characterised by the presence of both mononuclear and multinucleated (osteoclast-like) giant cell components. The nature of these component cells and the pathogenesis of the extensive osteolysis associated with this lesion is uncertain. METHODS: Using cell culture techniques and immunohistochemistry, we defined the phenotypic characteristics of the mononuclear and multinucleated cells present in four cases of GCG of the jaw. We also analysed the cellular and humoral factors associated with osteoclast formation and osteolysis in these tumours and determined whether GCG stromal cells are capable of supporting osteoclast formation. RESULTS: GCG-derived giant cells expressed the phenotypic characteristics of osteoclasts (TRAP+, VNR+, and calcitonin responsive) and were capable of lacunar resorption. In addition to macrophages, the mononuclear cell population contained numerous spindle-shaped stromal cells which proliferated in culture and expressed RANKL; these GCG-stromal cells were capable of supporting human osteoclast formation from circulating monocyte precursors. CONCLUSION: Our findings indicate that the giant cells in GCG of the jaw are osteoclast-like and formed from monocyte/macrophage precursors which differentiate into osteoclasts under the influence of RANKL-expressing mononuclear stromal cells found in this lesion.

A description for computed tomography based on sinusoidal curves.

A new description for computed tomography, parallel and equal to Radon transformation but based on sinusoidal functions rather than line integrals, is introduced. This representation contributes an effective algorithm to reduce metal artefacts in reconstruction. Using this method, the information included in the scan data corresponding to the metal implants can be separated from the original projection, an amending method rather than interpolation is therefore provided to reach higher accuracy for reconstruction. The method is with low complexity in computation, and can be combined online with filtered backprojection (FBP), which is the most widely used algorithm in practice, to improve the quality of the reconstructed image. Also, the method has the potential to deal with the artefacts caused by beam hardening and partial volume, and to be developed into a straight reconstruction algorithm based on the sinusoidal representation. Examples are presented for clearer description and demonstration.

Cellular and humoral mechanisms of osteoclast formation and bone resorption in Gorham-Stout disease.

Gorham-Stout disease (GSD) is a rare, massively osteolytic condition which is associated with increased vascularity and an increase in osteoclast numbers. To determine the cellular and humoral mechanisms underlying the increase in osteoclast numbers and osteolysis in GSD, this study analysed circulating osteoclast precursor numbers and sensitivity to osteoclastogenic factors in a GSD patient and age/sex-matched controls. Monocytes were cultured with M-CSF (25 ng/ml) and RANKL (30 ng/ml) and osteoclast formation was assessed in terms of the formation of TRAP(+) and VNR(+) multinucleated cells and the extent of lacunar resorption. There was no increase in the proportion of circulating osteoclast precursors in GSD relative to controls, but lacunar resorption was consistently greater in GSD monocyte cultures. Increased osteoclast formation in GSD was noted when monocytes were incubated with IL-1beta (1 ng/ml), IL-6/sIL-6R (100 ng/ml), and TNFalpha (10 ng/ml). An increase in osteoclast differentiation and bone resorption was also noted in control monocyte cultures in the presence of GSD serum. These results indicate that the increase in osteoclast formation in GSD is due not to an increase in the number of circulating osteoclast precursors, but rather to an increase in the sensitivity of these precursors to humoral factors which promote osteoclast formation and bone resorption.

The role of MRI in facial swelling due to presumed salivary gland disease.

50 consecutive patients presenting with facial swelling thought clinically to be due to salivary gland disease underwent MRI. Examinations were interpreted by one radiologist without access to previous investigations. Records were reviewed to determine the reliability and role of MRI in patient management, and the contribution of other prior or subsequent investigations. MRI findings were verified against operative findings, percutaneous biopsy or clinical follow-up (periods ranging from 8-58 months). A mass was found in 27 patients; in 11 of these patients, disease was extrinsic to the salivary gland. MRI diagnosis of tumour was correct in all patients and MRI was a reliable investigation for planning surgical resection. No mass was found in 23 patients, 8 of whom had normal appearances. Evidence of salivary duct dilatation was seen in 12 patients and fatty infiltration was seen in 3. MRI findings appeared correct in all patients. Prior investigation was undertaken in 29 patients, including orthopantomography, ultrasound and sialography; none provided additional information. Sialography was carried out in three patients after MRI and concurred with MRI in all cases. MRI was an adequate basis for management in all patients and therefore appears to be an effective first line investigation of facial swelling. It is reasonable for patients to undergo preliminary investigation for dental sepsis, this being the most common cause of facial swelling. Further study is required to determine whether MRI can completely replace invasive sialography.

Mefloquine-induced trigeminal sensory neuropathy.

Trigeminal sensory neuropathy is an important finding, often indicative of trauma but sometimes related to neoplasia, infections, demyelinating conditions, connective tissue disorders, other disorders, or, occasionally, drugs. This paper reports on a patient with sudden-onset trigeminal sensory neuropathy of the lip that proved to be drug-induced, secondary to the antimalarial drug mefloquine. This appears to be the first report of sensory impairment in the orofacial region from exposure to mefloquine.

Extraneural perineurioma of the face: an unusual cutaneous presentation of an uncommon tumour.

Perineurioma is an uncommon, benign tumour of the peripheral nerve sheath that has two major clinicopathological forms -- intraneural and extraneural. We present a case of extraneural perineurioma that occurred at an unusual site -- the facial skin of a 70-year-old woman -- which illustrates the wide, and potentially misleading, clinicopathological spectrum of this poorly recognized tumour.

Percutaneous endoscopic gastrostomy at the time of tumour resection in advanced oral cancer.

The role of percutaneous endoscopic gastrostomy (PEG) in patients undergoing resection of head and neck malignancy is well established. The procedure may be performed pre- or post-operatively with intravenous sedation or alternatively under general anaesthesia at the time of tumour resection. There are concerns as to the safety of PEG, particularly when performed under intravenous sedation. Elderly patients with poor general health and those with airway compromise may be at significant risk. We believe that patients with advanced oral malignancy often fall into such groups and, therefore, we routinely perform PEG at the time of resection. The aim of this study was to determine the potential risk factors for PEG insertion in patients with advanced oral malignancy and present our experience with insertion at the time of resection. A retrospective study was undertaken of the risk factors for PEG insertion in 72 consecutive patients with stage IV oral cancer treated between April 1993 and March 2000. Age, sex, tumour site, past medical history, American Society of Anaesthesiologists (ASA) and laryngoscopy grade, as an assessment of potential airway compromise, were recorded. There were 72 patients, 40 males and 32 females, with a mean age of 63 years (27-90). Eighteen patients (25%) scored 3 or 4 on the ASA scores of physical status. Laryngoscopy grades were recorded in 65 patients; of these, 18 (25%) had reduced visualisation of the larynx and in two patients not even the epiglottis could be seen. It is concluded that patients with advanced oral cancer have significant risk factors for PEG placement. However, PEG can be safely performed at the time of ablative surgery and has the advantage of avoiding an additional operative event for the patient.

Surgical emphysema and pneumomediastinum complicating dental extraction.

Subcutaneous and mediastinal emphysema is a rare complication of dental extraction and the use of air turbines has often been implicated. We describe a case which highlights a serious complication of the use of an air rotor for the removal of a right second mandibular molar.