Current role of computed tomography imaging in the evaluation of cartilage invasion by laryngeal carcinoma.

OBJECTIVES: To evaluate thyroid, arytenoid, and cricoid cartilage invasion on computed tomography (CT) imaging in patients undergoing total laryngectomy for both primary and recurrent laryngeal carcinoma. Secondary endpoint was to compare laryngeal cartilage invasion between primary and recurrent tumours. METHODS: Pre-treatment CT of 40 patients who had undergone total laryngectomy was retrospectively evaluated and compared with histology. Focal erosions of thyroid cartilage were accounted for neoplastic invasion of the inner cortex. Full-thickness thyroid cartilage invasion was defined as a tumour-like tissue replacing thyroid cartilage or extended in extra-laryngeal soft tissues. Sclerosis and erosion of arytenoid and cricoid cartilages were assessed as signs of neoplastic invasion. RESULTS: CT erosion showed perfect agreement for thyroid inner cortex and cricoid cartilage invasion and almost perfect agreement (87%) for arytenoid cartilage invasion. For tumours in contact with thyroid cartilages, the absence of CT erosion underestimated inner cortex infiltration. CT showed perfect agreement in predicting full-thickness thyroid cartilage invasion only in the case of extra-laryngeal neoplastic extension. Arytenoid sclerosis showed poor correlation with neoplastic invasion. For primary tumours, CT demonstrated good (inner cortex 75%; full-thickness 85%), substantial (67.5%), and perfect (100%) accuracy in thyroid, arytenoid, and cricoid cartilage invasion, respectively. No CT differences were observed between primary and recurrent laryngeal tumours. CONCLUSION: Tumour-like tissue extension in the extra-laryngeal soft tissues was accurate in predicting thyroid cartilage full-thickness invasion. Erosions of arytenoid, cricoid, and thyroid cartilages' inner cortex on CT were highly indicative of neoplastic infiltration. No CT difference in cartilage infiltration between primary and recurrent tumours was observed.

18F-FDG-PET/CT Imaging in Advanced Glottic Cancer: A Tool for Clinical Decision in Comparison with Conventional Imaging.

This study assessed the role of 18F-FDG PET-CT (PET/CT) to detect the cartilage and paraglottic infiltration in advanced glottic cancer comparing the results with those of conventional imaging (CI) (contrast-enhanced computed tomography and/or magnetic resonance). In addition, we assessed the prognostic value of quantitative parameters, measured on baseline PET/CT, in terms of event-free survival (EFS) and overall survival (OS). We retrospectively analyzed 27 patients with glottic squamous cell carcinoma stage III and IVA, treated in our institute between 2010 and 2016, comparing PET/CT, performed for staging and radiotherapy planning, and CI findings. Cohen's K was used to compare concordance between PET/CT and CI. Imaging findings were correlated with endoscopic evaluation and histological reports (gold standard (GS)). All lesions shown by CI were also detected by PET/CT imaging, and in 5 cases, a better definition of local infiltration was achieved with PET/CT than CI (5 CT). Sensitivity, specificity, and accuracy of PET/CT and CT were 95%, 86%, and 93% and 70%, 86%, and 74% for, respectively. MRI showed sensitivity and specificity of 100%. One false-negative (FN) cases and 1 false-positive (FP) case were observed with PET/CT with no difference compared to MRI (10 cases). Six FN cases and 1 FP case were observed with CT. Cohen's K was 0.60 (PET vs. CI) and 0.80 (PET vs. GS). Patients were followed-up for at least 24 months to calculate EFS and OS. 13 local recurrence and 7 deaths were recorded. Among quantitative PET parameters, baseline MTV was the most powerful predictor of outcome. Our data suggest a reliable sensitivity and accuracy of PET/CT in the evaluation of local extension, proving a useful method for initial local staging in addition to the well-established role in lymph-node and distant sites assessment. Furthermore, pretreatment MTV provides better prognostic information than other PET/CT parameters.

Multidetector CT of Laryngeal Injuries: Principles of Injury Recognition.

Blunt laryngeal trauma is associated with high morbidity and mortality. However, owing to their relatively rare occurrence, laryngeal injuries may be missed or underdiagnosed. Even subtle abnormalities at multidetector CT may correspond to significant functional abnormalities. It is important to understand normal CT laryngeal anatomy and develop a systematic review of the cervical soft tissues and laryngeal skeleton in patients who undergo screening CT cervical spine or other neck examinations in the setting of trauma, such as CT angiography. Multidetector CT findings of the normal larynx are reviewed, and blunt laryngeal injuries including soft-tissue edema, hematoma, mucosal lacerations, cartilage fracture, cricoarytenoid dislocation, and vocal fold paralysis are presented. The radiologist plays an important role in diagnosis and may be the first to identify laryngeal injuries that are not evident at physical examination. This article reviews normal laryngeal anatomy, presents various blunt laryngeal injuries at multidetector CT with case examples, discusses the role of multidetector CT in acute management, and describes pitfalls of diagnosis. ©RSNA, 2019.

Symmetrical Apophyses on the Posterior Margins of the Thyroid Cartilage: A Previously Undescribed Anatomical Variation With Potential Forensic Implications.

Differential diagnosis between normal/variant anatomy and pathological/traumatic findings represents one of the main matters of investigation of the so-called forensic clinical anatomy. In the literature, many anatomical variations of the laryngeal thyroid cartilage have been reported, with potential implications in forensic pathology. They include triticeal cartilages, foramen thyroideum, asymmetry, segmentation or agenesis of the superior thyroid horns, bone connections with the hyoid bone, absence of cricothyroid facets, hypertrophy of the inferior thyroid tubercle, and asymmetries in the thyroid notch, isthmus, or length of the inferior horn. In this report, we describe a laryngeal anatomical variation never described before, consisting of 2 apophyses symmetrically arising from the posterior margins of the thyroid laminae. Postmortem computed tomography performed on the laryngeal visceral block excluded previous traumatic injuries or natural pathologies of the laryngeal cartilages, confirming the congenital origin of the finding. An "omega epiglottis" and 3 laryngeal cysts in the piriform sinuses also coexisted, suggesting the possibility of underlying common developmental mechanisms.

Comparison of MR Imaging and Dual-Energy CT for the Evaluation of Cartilage Invasion by Laryngeal and Hypopharyngeal Squamous Cell Carcinoma.

BACKGROUND AND PURPOSE: Dual-energy CT can distinguish iodine-enhanced tumors from nonossified cartilage and has been investigated for evaluating cartilage invasion in patients with laryngeal and hypopharyngeal squamous cell carcinomas. In this study, we compared the diagnostic accuracy of MR imaging and of a combination of weighted-average and iodine overlay dual-energy CT images in detecting cartilage invasion by laryngeal and hypopharyngeal squamous cell carcinomas, in particular thyroid cartilage invasion. MATERIALS AND METHODS: Fifty-five consecutive patients who underwent 3T MR imaging and 128-slice dual-energy CT for preoperative initial staging of laryngeal or hypopharyngeal squamous cell carcinomas were included. Two blinded observers evaluated laryngeal cartilage invasion on MR imaging and dual-energy CT using a combination of weighted-average and iodine-overlay images. Pathologic findings of surgically resected specimens were used as the reference standard for evaluating sensitivity, specificity, and the areas under the receiver operating characteristic curve of both modalities for cartilage invasion by each type of cartilage and for all cartilages together. Sensitivity and specificity were compared using the McNemar test and generalized linear mixed models. RESULTS: Dual-energy CT showed higher specificity than MR imaging for diagnosing all cartilage together (84% for MR imaging versus 98% for dual-energy CT, P < .004) and for thyroid cartilage (64% versus 100%, P < .001), with a similar average area under the curve (0.94 versus 0.95, P = .70). The sensitivity did not differ significantly for all cartilages together (97% versus 81%, P = .16) and for thyroid cartilage (100% versus 89%, P = .50), though there was a trend toward increased sensitivity with MR imaging. CONCLUSIONS: Dual-energy CT showed higher specificity and acceptable sensitivity in diagnosing laryngeal cartilage invasion compared with MR imaging.

Local resectability assessment of head and neck cancer: Positron emission tomography/MRI versus positron emission tomography/CT.

BACKGROUND: The purpose of this study was to compare the diagnostic accuracy of positron emission tomography (PET)/MRI with PET/CT for local resectability of head and neck cancer. METHODS: Sequential contrast-enhanced PET/CT-MRI was performed in 58 patients referred for the staging or restaging of head and neck cancer. Tumors were assessed with PET/CT and PET/MRI for the presence of resectability-defining factors: T4b status (mediastinal invasion, invasion of the prevertebral space, and vascular encasement), and another 8 findings that would imply obstacles for surgical cure (invasion of the laryngeal cartilage, invasion of the preepiglottic fat pad, perineural spread, orbital invasion, bone infiltration, skull base invasion, dural infiltration, and invasion of the brachial plexus). RESULTS: The sensitivity/specificity/accuracy of local resectability-defining factors of PET/CT and PET/MRI was 0.92/0.99/0.98 and 0.98/0.99/0.99 (P = .727), respectively, per lesion, and 0.96/0.87/0.91 and 0.96/0.90/0.93 (P = .687), respectively, per patient. CONCLUSION: Both contrast-enhanced PET/MRI and contrast-enhanced PET/CT can serve as reliable examinations for defining local resectability of head and neck cancer.

Diagnostic accuracy of surface coil MRI in assessing cartilaginous invasion in laryngeal tumours: Do we need contrast-agent administration?

OBJECTIVES: To assess the diagnostic accuracy of MRI performed using surface coils, with and without contrast medium, in predicting thyroid and cricoid cartilage infiltration in laryngeal tumours, and to investigate whether the radiologist's experience influences diagnostic accuracy. METHODS: We retrospectively enrolled patients with biopsy-proven laryngeal cancer who had undergone preoperative staging MRI and open surgery. Two radiologists with different experience (senior vs. junior) reviewed the MR images without (session A1) and with contrast medium (session A2) separately. We calculated the accuracy of MRI with and without contrast medium in detecting infiltration of the thyroid and cricoid cartilages. Interobserver agreement was calculated by Cohen's Kappa (k). RESULTS: Forty-two patients were enrolled, for a total of 62 cartilages. In session A1 the senior and junior radiologists showed an accuracy of 85% and 71%, respectively, with k = 0.53 (0.33-0.72). In session A2 the senior and junior radiologists showed an accuracy of 84% and 77%, respectively, with k = 0.68 (0.49-0.86). CONCLUSIONS: Staging of laryngeal tumours with surface coil MRI showed good diagnostic accuracy in assessing cartilaginous infiltration. We observed similar values of diagnostic accuracy for the analysis performed with and without contrast medium for the senior radiologist. KEY POINTS: • Surface coil MRI demonstrated good accuracy in assessing laryngeal cartilage invasion. • The radiologist's experience can influence the diagnostic accuracy. • Gadolinium administration may increase interobserver concordance.

Triticeous Cartilage CT Imaging Characteristics, Prevalence, Extent, and Distribution of Ossification.

OBJECTIVE: The triticeous cartilage is a small ovoid cartilaginous structure variably present as a component of the laryngeal skeleton. This structure has received scant attention in the literature and has yet to be described adequately on cross-sectional imaging. STUDY DESIGN AND SETTING: Retrospective study in a tertiary medical center. SUBJECTS AND METHODS: We investigated triticeous cartilage prevalence in a large population utilizing computed tomography images. The cases of all patients with computed tomography angiography images of the neck from October 1, 2013, to September 31, 2014, were examined. A total of 663 patients were included in this study (age: range, 18-97 years; mean ± SD, 65 ± 15 years), 58.4% men and 41.6% women. The presence of a triticeal cartilage and its site, number, and degree of ossification were recorded. RESULTS: A total of 53.1% of patients had at least 1 triticeous cartilage (352 of 663). Prevalence was 57.4% (222 of 387) among men and 47.1% (130 of 276) among women. The presence of bilateral triticeous cartilages was more common than unilateral (63.1%, 222 of 352). A minority of patients (4.5%, 16 of 352) had a cartilaginous triticeous with no appreciable ossification, and more than half (54.0%, 190 of 352) had mild triticeal ossification. Moderate ossification was found in 34.9% of patients (123 of 352) and marked ossification in 6.5% (23 of 352). CONCLUSION: The presence of a triticeous cartilage is common and of variable appearance. As the clinical and surgical significance of this anatomic structure may be misinterpreted, it is important for imaging interpreters to be familiar with this seldom-recognized anatomic structure and recognize its variable appearance on cross-sectional imaging to avoid a misdiagnosis.

A systematic review of computed tomography detection of cartilage invasion in laryngeal carcinoma.

OBJECTIVES/HYPOTHESIS: This systematic review aimed to assess the diagnostic value of computed tomography (CT) in detecting cartilage invasion among patients with laryngeal carcinoma. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A search in the previously mentioned databases was performed to identify relevant articles. Articles comparing cartilage invasion on CT with histology were selected. After critical appraisal, articles of adequate relevance and validity were included in further analysis. Prevalences, sensitivity, specificity, positive predictive values, and negative predictive values were extracted from the included articles. RESULTS: Four studies were included in the final analysis. Only one study examined the positive predictive value and negative predictive value for invasion of any laryngeal cartilage, and they were 87% and 56%, respectively. The positive predictive value and negative predictive value for thyroid cartilage invasion were investigated in three studies and ranged from 44% to 80% and from 85% to 100%, respectively. The negative predictive value is likely underestimated due to selection bias, whereas the positive predictive value is likely overestimated. CONCLUSIONS: CT imaging is a suitable tool to assess laryngeal cartilage invasion, especially regarding the thyroid cartilage.

[Calcifications in the maxillofacial area]. / Meszesedések a maxillofaciális régióban.

Among patients presenting for dental treatment we could reveal various calcifications on panoramic x-rays or on cone beam computed tomography (CBCT) Calcifications is more likely to occur in vessels, ligaments, glandular tissues and is usually associated with chronic inflammation or scarring. The purpose of this article is to describe the imaging characteristics of commonly observed calcifications of the maxillofacial area with presenting our own cases such as: tonsilloliths, calcified lymph nodes, elongeated styloid process (calcified stylohyoid chain), phleboliths, carotid atheromas, calcified laryngeal cartilage.

Computed tomography-guided tissue engineering of upper airway cartilage.

Normal laryngeal function has a large impact on quality of life, and dysfunction can be life threatening. In general, airway obstructions arise from a reduction in neuromuscular function or a decrease in mechanical stiffness of the structures of the upper airway. These reductions decrease the ability of the airway to resist inspiratory or expiratory pressures, causing laryngeal collapse. We propose to restore airway patency through methods that replace damaged tissue and improve the stiffness of airway structures. A number of recent studies have utilized image-guided approaches to create cell-seeded constructs that reproduce the shape and size of the tissue of interest with high geometric fidelity. The objective of the present study was to establish a tissue engineering approach to the creation of viable constructs that approximate the shape and size of equine airway structures, in particular the epiglottis. Computed tomography images were used to create three-dimensional computer models of the cartilaginous structures of the larynx. Anatomically shaped injection molds were created from the three-dimensional models and were seeded with bovine auricular chondrocytes that were suspended within alginate before static culture. Constructs were then cultured for approximately 4 weeks post-seeding and evaluated for biochemical content, biomechanical properties, and histologic architecture. Results showed that the three-dimensional molded constructs had the approximate size and shape of the equine epiglottis and that it is possible to seed such constructs while maintaining 75%+ cell viability. Extracellular matrix content was observed to increase with time in culture and was accompanied by an increase in the mechanical stiffness of the construct. If successful, such an approach may represent a significant improvement on the currently available treatments for damaged airway cartilage and may provide clinical options for replacement of damaged tissue during treatment of obstructive airway disease.

Contrast-agent enhancement in ex vivo flat-panel computed tomography of locally advanced laryngeal cancer.

CONCLUSION: Visualization of cartilage invasion in ex vivo laryngectomy specimens was improved by flat-panel volumetric computed tomography (fpvCT) after diffusion of contrast agents. A prospective study to assess the specificity and sensitivity of this new method is warranted. OBJECTIVES: Cartilage invasion is a criterion for staging laryngeal squamous cell carcinoma. Contrast-enhanced CT is routinely used for assessing cartilage invasion. However, the sensitivities and specificities given for this method in the literature vary, and there is a need for improvement of this staging method. The objective of our pilot study was to determine cartilage invasion with fpvCT after contrast agent diffusion. METHODS: Three patients underwent preoperative CT and total laryngectomy. The excised larynges were immediately scanned with an fpvCT scanner, without contrast enhancement. Additional fpvCT scans were performed after incubation of the larynges in one of three different contrast agents for 24 and 48 h. The results from presurgical conventional scans, fpvCT scans, and histological examination - as the gold standard - were compared. RESULTS: We demonstrated the feasibility of ex vivo contrast enhancement of laryngeal tissues by diffusion, with a subsequent increase in contrast enhancement and improved visualization of cartilage invasion in fpvCT scans. Histology confirmed the fpvCT results.

Prognostic value of cartilage sclerosis in laryngeal cancer treated with primary radiation therapy.

OBJECTIVE: In patients with laryngeal cancer, pretreatment diagnosis of cartilage invasion often warrants a surgical or a bimodal treatment. Controversy exists on whether laryngeal cartilage sclerosis on computed tomography (CT) scan is a sign of tumor invasion. Our objective is to evaluate locoregional, laryngectomy-free, disease-specific, and overall survival in patients with laryngeal cancer with or without laryngeal cartilage sclerosis treated with primary radiation therapy. STUDY DESIGN: Historical cohort study. SETTING: Tertiary referral university center. SUBJECTS AND METHODS: All laryngeal cancer patients treated with primary radiation therapy between 2002 and 2007 were included. Patients with and without laryngeal cartilage sclerosis on CT scan were identified. Patient, tumor, and treatment data were collected. Univariate and multivariate analyses were conducted using Kaplan-Meier survival analyses and Cox proportional-hazards regression. RESULTS: One hundred eleven patients were included for analysis. Seventy-nine patients were classified as T1 or T2, and 32 patients were classified as T3 or T4. Twenty-three percent of patients had any laryngeal cartilage sclerosis, and 77% of patients had no sclerosis. On univariate and multivariate analyses, there was no statistically significant difference between patients with or without sclerosis. Results did not vary when studying each cartilage separately. CONCLUSION: Laryngeal cancer patients with cartilage sclerosis on CT scan do not have significantly different survival than patients without sclerosis. Validation of these results prospectively is warranted.

Computer-based analysis with three-dimensional imaging constructed from fine-slice computed tomography scan of supracricoid laryngectomy with cricohyoidoepiglottopexy: report of two cases.

OBJECTIVE: Supracricoid laryngectomy with cricohyoidoepiglottopexy is an organ-preserving surgical technique used to treat laryngeal cancer. This procedure resects the vocal folds; however, it is unclear how the sound source and airway morphology are involved in phonation through the post-operative neoglottis. METHOD: Multidetector helical computed tomography scanning was performed on two patients who had undergone supracricoid laryngectomy with cricohyoidoepiglottopexy. The cricoid and arytenoid cartilages and the airway were visualised using three-dimensional images. RESULTS: The mobility of the arytenoid cartilages was well preserved in the one patient with bilateral arytenoids, and in the other patient with only one arytenoid remaining. Two types of airway configuration were observed during phonation: one patient had a single stream airway, while the other had a combination of several streams. CONCLUSION: In the patient with only one arytenoid remaining, the preserved arytenoid tended to be rotated excessively inward. Therefore, phonation may have also occurred in various airways followed by mucosal vibration, which may be a sound source.

Local response to chemoradiation in T4 larynx cancer with cartilage invasion.

BACKGROUND: Patients with cartilage invasion were excluded from organ preservation protocols treating laryngeal and hypopharyngeal cancer. Treatment choice between chemoradiotherapy (CRT) and total laryngectomy (TL) remains controversial for these patients. OBJECTIVE: To assess local response and local recurrence after CRT for patients having T4 larynx or hypopharynx cancer with cartilage invasion. DESIGN: Retrospective intervention study. SETTING: : Tertiary-care, urban public hospital. PATIENTS: Patients with T4 squamous cell carcinoma of the larynx/hypopharynx with cartilage invasion treated from 2003 to 2009. INTERVENTION: Curative-intent CRT, compared to TL. OUTCOME MEASURES: Local response and local recurrence. RESULTS: Of 34 patients included in this study, 21 completed CRT and 13 underwent TL with postoperative RT or CRT. With CRT, 19 patients were noted to have a complete response at the primary site while two patients had persistent local disease. Of 19 patients with complete response, 4 developed local recurrence over a time period 76-226 days (mean: 177 days). This resulted in a 29% incidence of persistent/recurrent disease at the primary site. The remaining 15 patients (71%) remained free of local disease (mean follow-up: 369 days). For 13 patients undergoing TL with adjuvant therapy, there were no cases of local recurrence (mean follow-up: 389 days). CONCLUSIONS: Although there was a high initial complete response rate after CRT, this response was not durable with a high local recurrence rate within 1 year. In comparison, patients undergoing TL demonstrated markedly better local control. For patients with cartilage invasion, a prospective trial comparing medical versus surgical therapy is needed.

Overstaging of cartilage invasion by multidetector CT scan for laryngeal cancer and its potential effect on the use of organ preservation with chemoradiation.

OBJECTIVE: The two currently acceptable treatment options for locally advanced laryngeal cancer are total laryngectomy and organ preservation using chemoradiation. To facilitate therapeutic decision making, the accurate pre-treatment evaluation of cartilage invasion is of paramount importance. The purpose of this study was to evaluate the positive predictive value (PPV) and negative predictive value (NPV) of detecting neoplastic cartilage invasion in laryngeal cancer patients using fast-speed multidetector CT (MDCT). METHODS: 61 consecutive patients with clinically staged T3 or T4 squamous cell carcinoma of the larynx or hypopharynx who underwent total laryngectomy were analysed. All patients had MDCT of the neck within 2 weeks prior to surgery. Central radiographic and pathological review was performed in an attempt to correlate findings. MDCT invasion of cartilage was graded based on objective criteria. RESULTS: MDCT scan was found to have a PPV of 78% and an NPV of 100% for detection of invasion through cartilage, with sensitivity being 100% and specificity 96%. For detection of any cartilage invasion (minor, major or through cartilage invasion), PPV and NPV were 63% and 92%, respectively. The sensitivity was 85% and specificity was 75%. For the detection of tumour invasion through cartilage or major cartilage invasion, MDCT scan had a PPV of 53% and an NPV of 95%. 47% (9/19) patients were down-staged from T4 to T3 after central pathology review. CONCLUSION: The low PPV for cartilage destruction using MDCT suggests that a significant proportion of patients who were treated by total laryngectomy could have been appropriately offered organ preservation if more accurately staged at initial diagnosis.

Prognostic accuracy of computed tomography findings for patients with laryngeal cancer undergoing laryngectomy.

PURPOSE: The indications for upfront laryngectomy in the management of laryngeal cancer are a functionless larynx and extralaryngeal extension. Practically, clinicians rely on imaging to predict which patients will have T4 disease. Our goal was to review the accuracy of preoperative computed tomography (CT) scanning in determining the necessity for initial laryngectomy for advanced laryngeal cancer. PATIENTS AND METHODS: In total, 107 consecutive untreated laryngectomy specimens with high-quality, preoperative CT imaging interpreted by our neuroradiologists were reviewed. Radiographic findings, including sclerosis, invasion, penetration, extralaryngeal spread, and subglottic extension were correlated with pathologic findings. CT images were not reinterpreted, since our purpose was to assess the original interpretations. RESULTS: CT imaging reported 23 cases of thyroid cartilage penetration and 27 cases of extralaryngeal spread. Pathology reported 12 cases of thyroid cartilage invasion, 29 cases of penetration, and 45 cases of extralaryngeal disease. CT imaging identified 17 (59%) of 29 cases of pathologically documented thyroid cartilage penetration and 22 (49%) of 45 cases of pathologically documented extralaryngeal spread. Pathologically proven extralaryngeal spread without thyroid cartilage penetration occurred in 18 (40%) of 45 cases. The positive predictive values for thyroid cartilage penetration and extralaryngeal spread were 74% and 81%. Sclerosis was of limited value in predicting thyroid cartilage invasion or penetration. Cricoid or arytenoid destruction predicted for thyroid cartilage penetration at rates of 57% and 63%. CONCLUSION: CT imaging has clear limitations when deciding whether there is thyroid cartilage penetration or extralaryngeal spread of advanced laryngeal cancer. Extralaryngeal spread without thyroid cartilage penetration was more common than expected. Alternate methods of pretreatment assessment are needed.

Implementation of a virtual laryngoscope system using efficient reconstruction algorithms.

BACKGROUND: Conventional fiberoptic laryngoscope may cause discomfort to the patient and in some cases it can lead to side effects that include perforation, infection and hemorrhage. Virtual laryngoscopy (VL) can overcome this problem and further it may lower the risk of operation failures. Very few virtual endoscope (VE) based investigations of the larynx have been described in the literature. MATERIAL/METHODS: CT data sets from a healthy subject were used for the VL studies. An algorithm of preprocessing and region-growing for 3-D image segmentation is developed. An octree based approach is applied in our VL system which facilitates a rapid construction of iso-surfaces. Some locating techniques are used for fast rendering and navigation (fly-through). RESULTS: Our VL visualization system provides for real time and efficient 'fly-through' navigation. The virtual camera can be arranged so that it moves along the airway in either direction. Snap shots were taken during fly-throughs. The system can automatically adjust the direction of the virtual camera and prevent collisions of the camera and the wall of the airway. CONCLUSIONS: A virtual laryngoscope (VL) system using OpenGL (Open Graphics Library) platform for interactive rendering and 3D visualization of the laryngeal framework and upper airway is established. OpenGL is supported on major operating systems and works with every major windowing system. The VL system runs on regular PC workstations and was successfully tested and evaluated using CT data from a normal subject.

[Regional invasion of hypopharyngeal carcinoma base on CT--a report of 65 cases].

BACKGROUND AND OBJECTIVE: Identifying the characteristics of regional extension and accurately evaluating the extent of regional invasion is the key to delineate the target volume of hypopharyngeal carcinoma. This study was to investigate the characteristics of regional invasion of hypopharyngeal carcinoma using the enhanced computed tomography (CT) scan. METHODS: CT images of 65 patients with hypopharyngeal carcinoma treated at Sun Yat-sen University Cancer Center between August 2000 and September 2008 were retrospectively analyzed. The patients included 58 males and two females, with a median age of 55 years. RESULTS: Pyriform sinus carcinoma (50 cases)easily extended to aryepiglottic fold (98%), posterior hypopharyngeal wall (80%) and ipsilateral epiglottis (82%), preepiglottic space (66%), arytenoid cartilage (74%), paraglotic space (82%), ventricular bands (72%), vocal (62%), laminae of thyroid cartilage (58%) and lateral wall of oropharynx (52%). Posterior pharyngeal carcinoma (14 cases) usually invaded pyriform sinus (100%), aryepiglottic fold (92.9%), postcricoid region (71.4%), prevertebral fascia (71.4%) and esophagus (64.3%). One case of postcricoid carcinoma spread to pyriform sinus, posterior wall of hypopharynx, aryepiglottic fold, aryepiglottic cartilage, paraglotic space, cricoid cartilage thyroid cartilage and esophagus. CONCLUSION: Regional invasion of hypopharyngeal carcinoma is mainly direct extension through tissues. Tissues close to the primary tumor site and lack of regional tissue barrier are easier to be encroached and destroyed. The skip lesion is not detected. Routine prophylactic irradiation of nasopharynx and base of skull is not necessary.