Computed tomography assessment of maxillary sinus hypoplasia and associated anatomical variations: a systematic review and meta-analysis of global evidence.

OBJECTIVE: To summarize the scientific evidence on the prevalence of maxillary sinus hypoplasia (MSH) and associated anatomical variations as assessed by computed tomography scans. STUDY DESIGN: This PROSPERO-registered systematic review followed the recommendations of the PRISMA guidelines. Search algorithms were constructed for each of the six databases and gray literature. After screening the references (Rayyan®), the extracted data were meta-analyzed according to a random-effects model. The joanna briggs critical appraisal tool assessed the methodological quality of the included studies. The GRADE approach was used to estimate the certainty of the evidence. RESULTS: From a total of 2781 studies screened, 22 were considered for four meta-analysis. The prevalence of MSH in 7358 patients was 5.65% (CI95% = 4.07-7.47%) with significant heterogeneity between studies (p < 0.001, I2 = 89.30%). MSH was identified in 295 patients, of whom 82.38% (CI95% = 75.82-88.09%) had unilateral hypoplasia and 17.62% (CI95% = 11.91-24.18%) bilateral hypoplasia with moderate heterogeneity between studies (p < 0.0503, I2 = 42.87%). The prevalence of MSH in 9998 maxillary sinuses was 3.77% (95% CI = 2.44-5.38%), with significant heterogeneity between studies (p < 0.001, I2 = 92.84%). Hypoplastic/aplastic uncinate process, concha bullosa and paradoxical concha were the most reported anatomical variations. The studies presented a low-moderate methodological quality. The certainty of the evidence was very low to moderate. CONCLUSION: The prevalence of maxillary sinus hypoplasia observed was 5.65%, with most cases being unilateral.

A low-cost prosthetic orbital simulation model for endoscopic anterior ethmoid artery ligation.

OBJECTIVE: This study aimed to develop and evaluate a low-cost orbital prosthesis for simulation of endoscopically assisted intra-orbital anterior ethmoidal artery ligation. METHODS: A low-cost orbital prosthesis was built and evaluated by ENT surgical trainees. Feedback was given following the assessment in the form of a face validity questionnaire. RESULTS: Results were scored on a Likert scale of 1-7 (low to high). Trainees had limited exposure to the procedure (40 per cent) and predominantly low levels of confidence (mean, 3.67) that correlated with a lack of first-hand experience. The anatomy and likeness to human tissue of the prosthesis were both ranked highly, with mean scores of 5.0 and 4.93, respectively. CONCLUSION: The results of this study support the idea that a simple anatomical prosthesis for the simulation of endoscopic anterior ethmoidal artery ligation can be created with potential value to otolaryngology surgical training. To the authors' knowledge, this is the first documentation of simulated surgical epistaxis management using an artificial anatomical model.

Bone dehiscences of medial orbital wall on computed tomography and assessment of terminological errors in literature.

BACKGROUND: The objective of this study is to investigate the position and frequency of dehiscences in the medial orbital wall and to reveal that dehiscences and orbital adipose tissue hernias are distinct entities. MATERIALS AND METHODS: Two hundred-thirty medial orbital walls of 115 patients with a preliminary diagnosis of headache and sinusitis but without active ethmoidal sinusitis were examined by computer tomography in the axial plane. Two separate radiologists assessed continuity of the medial orbital wall and orbital fat tissue herniation in ethmoid cells. The medial orbital wall was divided into four quadrants and the dehiscence distribution was evaluated. RESULTS: Bone defects were detected in 71 (30.9%) patients in 230 orbital medial wall reviews of 115 patients (59 males, 56 females). Eight (3.5%) of these cases (4 male, 4 female) had herniation of the orbital adipose tissue into the ethmoid sinus. Of the 108 dehiscences, 47 were localised in the posterior upper quadrant. A statistically significant difference was found in the dehiscence distribution according to the quadrants. No significant relationship was found among age, gender, side of dehiscence and frequency of dehiscence. CONCLUSIONS: Dehiscences in the posterior upper quadrant are more common in the medial orbital wall. Although bone dehiscences in the medial orbital wall and the herniation of the orbital fat tissue are two different entities, they are used interchangeably in most of the literature and in radiological reporting.

Computed tomography assessment of anterior ethmoidal canal dehiscence: An interobserver agreement study and review of the literature.

PURPOSE: The anterior ethmoidal artery can be injured in functional endoscopic sinus surgery. The ability of computed tomography (CT) to identify dehiscence of the anterior ethmoidal canal (AEC) has not been widely evaluated. The aim of this study was to evaluate the interobserver agreement in the CT assessment of AEC dehiscence. METHODS: We conducted a retrospective review of consecutive CT scans of the paranasal sinuses (PNS) between January 1, 2012, and December 31, 2012. Two neuroradiologists separately assessed the presence of AEC dehiscence, the presence of PNS opacification, and the best CT plane to evaluate the AEC. Statistical analysis included descriptive analysis and interobserver agreement (kappa coefficient). RESULTS: The AEC was below the skull base in 199 (22.3%) cases. Dehiscence of the AEC was found in 13.2% for reader 1 and in 7.3% for reader 2. The interobserver agreement for identification of AEC dehiscence was only fair (κ = 0.246). The interobserver agreement for the AEC dehiscence in cases with opacification of ethmoidal air cells was substantial (κ = 0.754). CONCLUSION: The suboptimal interobserver agreement could potentially limit the usefulness of CT scans for routine assessment of AEC dehiscence. In patients with PNS opacification, CT scans could still add valuable information regarding AEC dehiscence.

Feasibility study of bilateral radical ethmoidectomy in ambulatory surgery.

OBJECTIVES: To assess the feasibility of bilateral radical ethmoidectomy in ambulatory surgery by risk analysis, and to calculate possible medico-economic savings. METHODS: This study was performed retrospectively over a 2-year period and prospectively for 1 year. It included all patients undergoing bilateral ethmoidectomy, associated to sphenoidotomy and/or septoplasty or not, in a university hospital department. Data were collected on demographics, disease etiology, previous surgery, operative details, postoperative course, complications and satisfaction assessed by questionnaire at days 1 and 30. Ambulatory surgery eligibility criteria were applied to this population, and an economic analysis compared savings between inpatient and outpatient management. RESULTS: Hundred and sixty-five patients were included. Surgical indications comprised nasal polyposis (87%), chronic sinusitis without nasal polyps (6%) or cystic fibrosis (7%). Seventy-five septoplasties were associated (45.5%). Operating time depended on associated septoplasty (P=0.005), surgeon experience (P<0.0001) and previous sinus surgery (P=0.041). Only 37% of the patients wished for same-day discharge; reasons for refusal were home-to-hospital distance and bleeding risk. Considering anesthesia contraindications, immediate complications and operating time, 107 patients were eligible for outpatient treatment, although only 13 patients underwent ambulatory surgery. Medical-economic savings with outpatient management would have been about €20,000 per year. CONCLUSIONS: Bilateral radical ethmoidectomy, associated to septoplasty or not, could be performed on an outpatient basis in more than 60% of cases, without increased risk, and with cost savings of 28.4%.

Patient and surgeon factors explain variation in the frequency of frontal sinus surgery.

OBJECTIVES/HYPOTHESIS: Ethmoidectomy may be sufficient to address frontal sinus disease, but some surgeons may perform frontal recess dissection initially. Our objectives were to describe patient-associated factors with frequency of frontal sinus surgery and analyze the association with provider volume. STUDY DESIGN: Retrospective cohort analysis. METHODS: The 2013 State Ambulatory Surgery Databases of New Jersey, Florida, and Kentucky were queried to identify adults who underwent anterior ethmoidectomy or total ethmoidectomy using standard Current Procedural Terminology codes. Univariate and multivariate logistic regression was performed to determine the odds of undergoing concurrent frontal sinus exploration along with ethmoidectomy, adjusting for age, gender, race, insurance type, median income, and the metropolitan designation by zip code. We also examined provider and center volume, use of image guidance, and total charges. RESULTS: There were 10,564 ethmoidectomies, of which 4,726 had concurrent frontal sinus surgery. Women were less likely to have frontal sinus surgery (P = .0011), as were patients with Medicare (P = .007). Hispanics were more likely to have frontal sinus surgery (P = .0003). Surgeons with higher surgical volumes were more likely to perform frontal sinus surgery; it was also more likely to be performed in centers where more sinus procedures occurred (P < .0001, both). CONCLUSIONS: Variation in the utilization of frontal sinus surgery is associated with patient sex, ethnicity, insurance status, geography, as well as provider and hospital volumes. These data support the idea that nonclinical factors may influence the treatment of frontal sinus disease. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:2008-2014, 2018.

Melanomas nasosinusales / Sinonasal melanomas

Los melanomas mucosos representan 2 a 8% de todos los melanomas de cabeza y cuello. La mayoría se localizan en la cavidad nasal y senos paranasales. El objetivo de este estudio fue revisar la evolución de pacientes portadores de melanomas malignos nasosinusales (MMNS) en un hospital de atención terciaria. Material y Métodos: Serie de casos de 19 pacientes operados por MMNS en el Hospital "Carlos Andrade Marín" y algunos institutos privados de Quito. Todos con diagnóstico histológico confirmado. Resultados: Once varones con una edad promedio de 64 años. Sus síntomas más frecuentes fueron obstrucción nasal y epistaxis y la mayor parte de los tumores se localizaron en la fosa nasal. En 11 pacientes se encontró extensión extranasal. Doce pacientes estuvieron en estadios III-IV. Todos los pacientes recibieron tratamiento quirúrgico y siete de ellos radioterapia complementaria. Recurrencia local (11 eventos) ocurrió en 9 casos. Estos eventos fueron tratados con cirugía en ocho pacientes, que eventualmente recibieron radioterapia (RT) y quimioterapia (QT). 0cho de estos nueve pacientes fallecieron. La sobrevida global a 5 años fue del 46%. La mortalidad estuvo relacionada con la extensión de la enfermedad local y la presencia de metástasis. Todos los pacientes con estadio I están vivos. Discusión: La mayor parte de MMNS tiene mal pronóstico debido ­ principalmente- a enfermedad local inicialmente avanzada, recurrencia local y metástasis a distancia. La cirugía es el tratamiento de base seguido de RT.

Introduction: Head and neck mucosal melanoma account for 2 to 8% of head and neck melanomas, most of them arising in the nasal cavity or paranasal sinuses. The aim of this report was to review the follow up of patients with sinonasal malignant melanomas (SNMM), treated over a long period of time at a tertiary referral hospital. Methods: Case series of 19 patients surgically treated for SNMM at Social Security Hospital Carlos Andrade Marin and other private clinics from Quito Ecuador. All patients had histologically proven diagnosis; eleven men. Results: The mean age was 64 year-old. The most common symptoms were nasal obstruction and epistaxis. Most tumors were located at the nasal fossa. Extranasal extension occurred in 11 patients. Twelve tumor were at stages III-IV. All patients were surgically treated. Postoperative radiotherapy was given to 7 patients. Local recurrence (11 events) occurred in 9 cases. These events were treated with surgery in 8 patients, eventually associated to radiation therapy (RT) and chemotherapy (CT). Eight out of 9 patients died. Overall survival was 46%. Death was related to extension of the disease and distant metastases. All stage I tumor patients are still alive. Discussion: Most sinonasal melanomas have a poor prognosis, mainly attributed to initial advanced local disease, local recurrence and distant metastasis.

Radiological Assessment of the Anatomy of Frontal Recess Cells and the Anterior Ethmoidal Artery.

It is necessary for the surgeon to be familiar with frontal recess anatomy during an endoscopic approach to the frontal sinuses. The aim of this study was to evaluate the prevalence of frontal recess cells in Japanese adults as well as the association between the frontal recess and the location of the anterior ethmoidal artery (AEA). The frontal recess cells and the AEAs were retrospectively evaluated in CT scans of the nasal and paranasal sinuses for 89 patients. The prevalence of agger nasi cells was 90.7%. The frequency of frontal cell types 1, 2, 3 and 4 was 28.8, 0.6, 2.6 and 0%, respectively. Suprabullar cells (SBCs) and frontal bullar cells (FBCs) were identified in 78/96 sides (81.3%) and 24/96 sides (24%), respectively. The prevalence of the medial group of frontal recess cells (interfrontal sinus septal cells) was 12.4%. In 42/61 sides (68.9%), the AEAs were located within the posterior margin of the SBCs or the FBCs. Therefore, SBCs, FBCs and the vertical portion of the middle turbinate are reliable landmarks for the identification of AEAs.

Tromboflebite séptica de seio cavernoso comespessamento meníngeo de base de crânio / Cavernous sinus septic thrombophlebitis with skull base meningitis

O seio cavernoso é um sítio frequente de ocorrência de tromboseséptica, frequentemente secundária a infecções de seios da face, órbitas,tonsilas, palato, dentes, seios esfenoidal e etmoidal. Este artigorelata o caso de uma paciente de 25 anos com sinusopatia queevoluiu com complicações após um mês apresentando anisocoria,ptose palpebral incompleta à direita, paralisia do olhar horizontal,paralisia facial central, queda de véu palatino, ausência de reflexonauseoso à direita e desvio de língua para esquerda. Realizou examede imagem que identificou acometimento de seio cavernoso eespessamento meníngeo adjacente. A tromboflebite do seio cavernoso(TSC) comumente afeta os nervos cranianos que o cruzam,constituindo-se em uma complicação incomum de infecções depele, órbitas ou seios da face. A singularidade deste caso esteve nadificuldade de tratamento, no acometimento contínuo das meningesda base de crânio e, consequentemente, dos nervos cranianosdessa topografia (VII, IX e XII). O tratamento com anticoagulantesnão é consenso na literatura, devido a complicações hemorrágicasque podem ocorrer no sítio do trombo. A importância do tratamentoadequado e precoce das infecções dos seios esfenoidal e etmoidal,além de infecções de face, nariz, tonsilas, dentes e ouvidos evita disseminaçãobacteriana e complicações, como as descritas neste caso.(AU)

The cavernous sinus is a rare site of septic thrombosis. It is associatedwith significant morbidity or mortality and is often related tolocal infection of the paranasal sinuses, orbits, tonsils, palate andteeth. This article presents a 25-year-old woman presented to ourclinic with a history of anisocoria, right incomplete ptosis, horizontalgaze palsy, central facial palsy, right absence of garg reflexand left tongue deviation. Further work up with cranial magneticresonance imaging revealed a meningeal enhancement at the skullbase and signal alteration at the cavernous sinus suggestive of septicthrombosis. Cavernous sinus thrombophlebitis is a complication ofskin, orbits or sinuses infections that typically causes cranial nervepalsies. We would like to emphasize that meningeal involvement atskull base can complicate the clinical course especially when thereis involvement of multiple cranial nerves. Anticoagulation theraphyis not a consensus in the literature due to the risk of hemorrhagiccomplications that may occur on the site of the thrombus. Theadequate and early treatment of infections of the sphenoid and ethmoidalsinuses, infections of nose, tonsils, teeth and ears can avoidbacterial disseminations and prevents complications, as describedin this case.(AU)

Near Real-Time Assessment of Anatomic and Dosimetric Variations for Head and Neck Radiation Therapy via Graphics Processing Unit-based Dose Deformation Framework.

PURPOSE: The purpose of this study was to systematically monitor anatomic variations and their dosimetric consequences during intensity modulated radiation therapy (IMRT) for head and neck (H&N) cancer by using a graphics processing unit (GPU)-based deformable image registration (DIR) framework. METHODS AND MATERIALS: Eleven IMRT H&N patients undergoing IMRT with daily megavoltage computed tomography (CT) and weekly kilovoltage CT (kVCT) scans were included in this analysis. Pretreatment kVCTs were automatically registered with their corresponding planning CTs through a GPU-based DIR framework. The deformation of each contoured structure in the H&N region was computed to account for nonrigid change in the patient setup. The Jacobian determinant of the planning target volumes and the surrounding critical structures were used to quantify anatomical volume changes. The actual delivered dose was calculated accounting for the organ deformation. The dose distribution uncertainties due to registration errors were estimated using a landmark-based gamma evaluation. RESULTS: Dramatic interfractional anatomic changes were observed. During the treatment course of 6 to 7 weeks, the parotid gland volumes changed up to 34.7%, and the center-of-mass displacement of the 2 parotid glands varied in the range of 0.9 to 8.8 mm. For the primary treatment volume, the cumulative minimum and mean and equivalent uniform doses assessed by the weekly kVCTs were lower than the planned doses by up to 14.9% (P=.14), 2% (P=.39), and 7.3% (P=.05), respectively. The cumulative mean doses were significantly higher than the planned dose for the left parotid (P=.03) and right parotid glands (P=.006). The computation including DIR and dose accumulation was ultrafast (∼45 seconds) with registration accuracy at the subvoxel level. CONCLUSIONS: A systematic analysis of anatomic variations in the H&N region and their dosimetric consequences is critical in improving treatment efficacy. Nearly real-time assessment of anatomic and dosimetric variations is feasible using the GPU-based DIR framework. Clinical implementation of this technology may enable timely plan adaptation and improved outcome.

Technical feasibility of transnasal endoscopic anterior ethmoid artery ligation: assessment with intraoperative CT imaging.

BACKGROUND: The objective of this study was to evaluate the technical feasibility of endoscopic anterior ethmoid artery (AEA) ligation for acute control of epistaxis. METHODS: A prospective study was conducted using eight cadaver heads. Pre- and intraoperative CT scans were performed using the xCAT (Xoran Technologies, Inc., Ann Arbor, MI). Skull base anatomy relative to the AEA was reviewed preoperatively. Endoscopic AEA ligation was attempted in all sides with a mesentery. Ligation was not deemed feasible in AEAs without a mesentery. It was attempted on two sides without a mesentery to assess risk of skull base and orbital disruption. Intraoperative CT scans were performed to assess the position of the clips and the integrity of the skull base and lamina papyracea. RESULTS: The mean lateral lamella height was 4.75 and 4.83 mm on the right and left, respectively. Of the 16 arteries, 6 (37.5%) of the AEAs were within a bony mesentery. No AEA canals were dehiscent. Four of the six AEAs (66%) within a mesentery were successfully clipped and two (33%) were partially clipped by endoscopic evaluation. Both arteries without mesentery where clipping was attempted were partially clipped by endoscopic examination. Review of intraoperative CT scans showed that the AEA with a mesentery was clipped successfully on three sides, partially on one side, and unsuccessfully on two sides. AEA clipping was unsuccessful on both sides without a mesentery. One AEA without a mesentery showed skull base disruption after ligation by endoscopy and CT. None of the specimens showed orbital injury. CONCLUSION: Intraoperative CT scanning revealed that AEA ligation was less successful than was apparent endoscopically. Effective AEA clipping was performed in 50% of cases with a mesentery. Endoscopic clipping was not technically feasible in cases with AEA without a mesentery. Overall, AEA clipping was only technically feasible in 3 of 16 sides (18.8%).

Análise por tomografia computadorizada do teto etmoidal: importante área de risco em cirurgia endoscópica nasal / Computed tomography assessment of the ethmoid roof: a relevant region at risk in endoscopic sinus surgery

OBJETIVO: Avaliar a profundidade das fossas olfatórias e a freqüência de assimetria na altura e na inclinação lateral do contorno do teto etmoidal. MATERIAIS E MÉTODOS: Estudo retrospectivo de 200 tomografias computadorizadas dos seios da face no plano coronal realizadas no período de agosto a dezembro de 2006. As profundidades das fossas olfatórias foram classificadas segundo Keros. O teto etmoidal foi avaliado quanto à simetria entre os lados. RESULTADOS: O tipo de Keros mais encontrado foi o tipo II (73,3 por cento), seguido do tipo I (26,3 por cento) e do tipo III (0,5 por cento). Em 12 por cento (24 exames) havia assimetria entre os lados quanto à altura do teto etmoidal, e em 48,5 por cento (97 exames) observou-se assimetria do contorno do teto, com inclinação lateral da lâmina crivosa de um dos lados. CONCLUSÃO: Em relação à profundidade das fossas olfatórias, o tipo II de Keros foi o mais freqüente. Verificou-se que a assimetria do teto do seio etmoidal, na maioria dos casos, estava relacionada com a inclinação lateral da lamela lateral da lâmina crivosa.

OBJECTIVE: To evaluate the olfactory fossae depth according to the Keros' classification and determine the incidence and degree of asymmetry in the height and contour of the ethmoid roof. MATERIALS AND METHODS: Retrospective analysis of 200 coronal computed tomography studies of paranasal sinuses performed in the period between August and December, 2006. RESULTS: According to the Keros' classification, olfactory fossae type II was most frequently found in 73.3 percent of cases followed by type I in 26.3 percent and type III in 0.5 percent of cases. Asymmetry in the ethmoid roof height was found in 12 percent of cases (24 computed tomography studies), and contour asymmetry was found in 48.5 percent (97 computed tomography studies), with flattening of the ethmoid roof on one of the sides. CONCLUSION: As regards the olfactory fossae depth, the Keros' type II was most frequently found. In most of cases, the ethmoid roof asymmetry was related to angulation of the lateral lamella of the cribriform plate.

Evaluation of uncertainty-based stopping criteria for monte carlo calculations of intensity-modulated radiotherapy and arc therapy patient dose distributions.

PURPOSE: To formulate uncertainty-based stopping criteria for Monte Carlo (MC) calculations of intensity-modulated radiotherapy and intensity-modulated arc therapy patient dose distributions and evaluate their influence on MC simulation times and dose characteristics. METHODS AND MATERIALS: For each structure of interest, stopping criteria were formulated as follows: sigma(rel) or=95% of the voxels, where sigma(rel) represents the relative statistical uncertainty on the estimated dose, D. The tolerated uncertainty (sigma(rel,tol)) was 2%. The dose limit (D(lim)) equaled the planning target volume (PTV) prescription dose or a dose value related to the organ at risk (OAR) planning constraints. An intensity-modulated radiotherapy-lung, intensity-modulated radiotherapy-ethmoid sinus, and intensity-modulated arc therapy-rectum patient case were studied. The PTV-stopping criteria-based calculations were compared with the PTV+OAR-stopping criteria-based calculations. RESULTS: The MC dose distributions complied with the PTV-stopping criteria after 14% (lung), 21% (ethmoid), and 12% (rectum) of the simulation times of a 100 million histories reference calculation, and increased to 29%, 44%, and 51%, respectively, by the addition of the OAR-stopping criteria. Dose-volume histograms corresponding to the PTV-stopping criteria, PTV+OAR-stopping criteria, and reference dose calculations were indiscernible. The median local dose differences between the PTV-stopping criteria and the reference calculations amounted to 1.4% (lung), 2.1% (ethmoid), and 2.5% (rectum). CONCLUSIONS: For the patient cases studied, the MC calculations using PTV-stopping criteria only allowed accurate treatment plan evaluation. The proposed stopping criteria provided a flexible tool to assist MC patient dose calculations. The structures of interest and appropriate values of sigma(rel,tol) and D(lim) should be selected for each patient individually according to the clinical treatment planning goals.

A new force-based objective assessment of technical skills in endoscopic sinus surgery.

We propose objectively assessing endoscopic sinus surgery (ESS) skills by measuring the force applied to a patient model. We collected data on 16 subjects performing gauze packing task using a precise human nasal model with a six-degree-of-freedom force/torque sensor. Mann-Whitney's U test was used to analyze their performance. Intermediates (ESS: 10-50 cases) used significantly greater force than students or experts (ESS: over 150 cases) at the 5 % level. Maximum force improved only among experts. These results imply that young surgeons pay too little attention to force applied to patients or tissues.

D2-40 immunohistochemical assessment of lymphangiogenesis in normal and edematous sinus mucosa and nasal polyp.

OBJECTIVE: The lymphatic system plays an important role in the maintenance of tissue fluid homeostasis, which facilitates interstitial protein transport. Until recently, the lymphatic system of the sinonasal mucosa has been relatively poorly studied. The authors aimed to investigate the distributional and quantitative changes of the lymphatic vessels in inflammatory sinus mucosa and nasal polyps in comparison with healthy sinus mucosa using D2-40 antibody. METHODS: Immunohistochemistry and Western blotting with D2-40 antibody were applied to normal and edematous ethmoid sinus mucosa and nasal polyps. The number, size, and length densities of lymphatic vessels were evaluated using tissue sections and whole mount preparations. RESULTS: Most lymphatic vessels in normal and edematous ethmoid sinus mucosa were distributed in the subepithelial layer. Some of these vessels were dilated, whereas others were compressed and had a slit-like lumen. No D2-40 positive vessels were found in samples of nasal polyps. Lymphatic vessels showed no statistically significant difference in their number, size, or length density between normal and edematous ethmoid sinus mucosa. Western blot also showed no differences in their expression levels. CONCLUSION: These findings indicate that lymphangiogenesis does not occur in edematous ethmoid sinus mucosa, which may not reuptake interstitial fluid efficiently in inflammatory conditions, resulting in the formation of mucosal edema in chronic inflammation.

Endoscopic transnasal transethmosphenoidal approach for pituitary tumors: assessment of technique and postoperative findings of nasal and paranasal cavities.

OBJECTIVE: Transnasal endoscopic surgery is the most common approach to removal of pituitary tumors. This study evaluated the transnasal transethmosphenoidal approach (TTES) in terms of its operative manipulability and the postoperative status of the paranasal cavities. METHODS: A total of 132 patients with pituitary tumors underwent surgery by one of the following three approaches: (1) bilateral TTES, in which the surgical procedures were performed via the bilateral paranasal cavities, (2) unilateral TTES, in which the procedures were performed via one side only, and (3) unilateral TTES and resection of the posterior portion in the nasal septum approach (RPS), which is a modification of approach (2) and enables performance of the procedures from both sides. RESULTS: The degree of freedom for the surgical procedures with each of the approaches decreased in the following order: bilateral TTES, unilateral TTES and RPS, and unilateral TTES. The postoperative CT images and endoscopic findings were good with each of the surgical approaches, but the incidences of olfactory disturbance and nasal dryness were significantly higher with the bilateral TTES compared with the unilateral TTES and RPS and the unilateral TTES. CONCLUSION: The unilateral TTES and RPS was for us most suitable approach of the three methods. In the case of advanced tumors, the bilateral TTES should be selected because it permits superior operative manipulability. Finally, the unilateral TTES is most appropriate for removal of tumors that are deviated to one side and localized within the sella.

Comparison of dose-volume histograms of IMRT treatment plans for ethmoid sinus cancer computed by advanced treatment planning systems including Monte Carlo.

BACKGROUND AND PURPOSE: To recompute clinical intensity-modulated treatment plans for ethmoid sinus cancer and to compare quantitatively the dose-volume histograms (DVHs) of the planning target volume (PTV) and the optic organs at risk. MATERIAL AND METHODS: Ten step-and-shoot intensity-modulated treatment plans were enrolled in this study. Large natural and surgical air cavities challenged the calculation systems. Each optimized treatment plan was recalculated by two superposition convolution (TMS and Pinnacle) and a Monte Carlo system (MCDE). To compare the resulting DVHs, a one-way ANOVA for repeated measurements was performed and multiple pairwise comparisons were made. RESULTS: The tails of the PTV-DVHs were significantly higher for the Monte Carlo system. The DVHs of the critical organs displayed some statistically but not always clinically significant differences. For the individual patients, the three planning systems sometimes reproduced clinically discrepant DVHs that were not significantly different when averaged over all patients. CONCLUSIONS: Dose to air cavities contains computational uncertainty. As this dose is clinically irrelevant and optimizing it is meaningless, we recommended extracting the air from the PTV when constructing the PTV-DVH. The planning systems considered reproduce DVHs that are significantly different, especially in the tail region of PTV-DVHs.

MCDE: a new Monte Carlo dose engine for IMRT.

A new accurate Monte Carlo code for IMRT dose computations, MCDE (Monte Carlo dose engine), is introduced. MCDE is based on BEAMnrc/DOSXYZnrc and consequently the accurate EGSnrc electron transport. DOSXYZnrc is reprogrammed as a component module for BEAMnrc. In this way both codes are interconnected elegantly, while maintaining the BEAM structure and only minimal changes to BEAMnrc.mortran are necessary. The treatment head of the Elekta SLiplus linear accelerator is modelled in detail. CT grids consisting of up to 200 slices of 512 x 512 voxels can be introduced and up to 100 beams can be handled simultaneously. The beams and CT data are imported from the treatment planning system GRATIS via a DICOM interface. To enable the handling of up to 50 x 10(6) voxels the system was programmed in Fortran95 to enable dynamic memory management. All region-dependent arrays (dose, statistics, transport arrays) were redefined. A scoring grid was introduced and superimposed on the geometry grid, to be able to limit the number of scoring voxels. The whole system uses approximately 200 MB of RAM and runs on a PC cluster consisting of 38 1.0 GHz processors. A set of in-house made scripts handle the parallellization and the centralization of the Monte Carlo calculations on a server. As an illustration of MCDE, a clinical example is discussed and compared with collapsed cone convolution calculations. At present, the system is still rather slow and is intended to be a tool for reliable verification of IMRT treatment planning in the case of the presence of tissue inhomogeneities such as air cavities.

Modern imaging of paranasal sinuses and the role of limited sinus computerized tomography; considerations of time, cost and radiation.

The modern diagnostic radiology department is equipped with a variety of medical imaging systems that can be used for evaluation of diseases of the sinonasal cavities. Each has advantages and disadvantages. The imaging examinations of the paranasal sinuses may include conventional films, complex motion tomography, computed tomography (CT) and magnetic resonance imaging (MRI). The indications for these imaging methods are reviewed, along with a discussion on the role of imaging for endoscopic sinus surgery. A summary of CT anatomy relating to the ethmoidal sinuses and ostiomeatal complex is given, as is a review of the risk of radiation for radiologic sinus imaging.