Paranasal Sinus Computed Tomography Research Articles

A comprehensive morphometric analysis of crista galli for sex determination with a novel morphological classification on computed tomography images.

This study aimed to examine the morphometry of the crista galli (CG) on paranasal sinus computed tomography (PNCT) images to develop a new approach of morphological classification with objective radiological criteria and to investigate the relationship of morphometric and morphological characteristics with gender. The height, width, and length of the CG were measured on the PNCT images of 533 subjects (266 males, 267 females). Based on the dimensions and the presence of the cavitary component of the CG, the CG was classified into three morphological types. The success of CG dimensions and new morphological classification of CG in the determination of gender was evaluated with ROC and Paired Logistic Regression analyses. The morphometric cutoff values of the height, width, and length of the CG for the estimation of gender were determined as 15.15, 3.45, and 13.25mm, respectively. CG length (accuracy 83.7%) showed more successful classification rate on gender determination as compared to height (accuracy: 81.4%), and width (accuracy 81.2%) of the CG. The presence of ossified type CG accurately identified the male sex at a rate of 88.7%, and teardrop type CG determined female sex at a rate of 82.9%. Tubular type CG identified male sex correctly at the rate of 65.8%. The height, length, and width measurements of CG on PNCT images and the new morphological types recommended in this study can be used in the determination of gender with high accuracy rates.

Delayed Sudden Blindness From Unilateral Ophthalmic Artery Vasospasm Following Endoscopic Sinus Surgery?

Keywords: ophthalmic artery; vasospasm; iatrogenic; endoscopic sinus surgery; blindness
 
 Endoscopic sinus surgery (ESS) is a generally benign, minimally invasive procedure used for management of paranasal sinus diseases, although complications may occur due to proximity of vital structures such as the brain, orbit and great vessels.1 The overall ESS major complication rate is 0.5-1%, of which orbital injury accounts for 0.09% due to direct trauma.2 We report a case of unilateral delayed sudden visual loss without orbital trauma observed intraoperatively or on post[1]operative imaging studies, following a seemingly routine endoscopic sinus surgery for chronic rhinosinusitis.
 CASE REPORT
 An 18-year-old lad with no significant medical history underwent ESS for bilateral chronic rhinosinusitis with nasal polyposis. (Figure 1 A-D) The surgery and recovery from anesthesia were uneventful. On the 12th hour post-operatively, the patient noted blurring of vision on the left. Ophthalmologic examination revealed hyperemic conjunctiva (Figure 2A) with visual acuity of counting fingers at 1 foot while fundoscopy showed retinal hemorrhages. Extraocular eye movements (EOM) and intraocular pressure (IOP) were normal (12mmHg). With an assessment of pre-retinal hemorrhages, 500 mg Tranexamic acid was intravenously infused, and a paranasal sinus (PNS) computed tomography (CT) scan and orbital magnetic resonance imaging (MRI) were requested. A few hours later, he complained of left eye pain with increasing intensity and further deterioration of vision. Repeat visual acuity testing showed light perception. There was now a constricted pupil, non-reactive pupillary light reflex, periorbital swelling and progression of conjunctival chemosis. (Figure 2B) The IOP of the left eye had increased to 30mmHg then progressed to 40mmHg with development of total visual loss and a lateral gaze limitation. With an impression of choroidal hemorrhage and retrobulbar hemorrhage, a lateral canthotomy relieved the eye pain.
 The contrast PNS CT scan with orbital cuts showed that the lamina papyracea was intact with no definite hemorrhagic collections in the intraconal or extraconal spaces of both orbits. (Figure 3A, B) A small hyper density along the lateral inferior margin of the left globe at the intraconal region with slight thickening of the anterior periorbital region represented the lateral canthotomy. The PNS MRI / magnetic resonance angiography (MRA) with orbital cuts showed retinal detachment and periorbital edema in the left eye. (Figure 4) A B-Scan ocular ultrasonogram showed retinal detachment and vitreous opacities. The diagnosis was ocular ischemic syndrome secondary to ophthalmic artery vasospasm, and the patient was given sublingual nitroglycerine and intravenous dexamethasone 8mg every 12 hours for 24 hours, with improvement of periorbital swelling. He was discharged after 12 days with no resolution of the unilateral visual loss.

ORTA ANADOLU'DA KRONİK RİNOSİNÜZİTİN BİREYSEL ÖZELLİKLER VE ÇEVRESEL FAKTÖRLERLE İLİŞKİSİ

OBJECTIVE: The aims of this study were to investigate the prevalence and distribution of sinonasal diseases in patients that underwent paranasal sinus computed tomography (CT) due to chronic rhinosinusitis (CRS) with or without nasal polyps, and to explore the association between CRS and sinonasal variations and the effect of environmental factors.MATERIAL AND METHODS: The paranasal sinus CT images and files of 1000 patients that referred to a tertiary health center in Ankara were retrospectively evaluated. The CT findings, smoking status, presence of allergies, place of residence (urban/rural), and history of functional endoscopic sinus surgery were noted.RESULTS: CRS was seen in 68% of the patients, and most common in maxillary sinuses (53%). Nasal polyps with CRS were noted in 11% of the cases. CRS was also more common among smokers (p<0.001). In CRS accompanied by nasal polyps, no difference was found between urban and rural residence. However, most cases of CRS with nasal polyps lived in urban areas (81.4%, p=0.006). There was no difference between allergy and CRS with and without nasal polyps or between sinonasal variations and CRS development.CONCLUSIONS: In the region investigated, the prevalence of CRS with nasal polyps was higher in the urban area (higher air pollution); however, the prevalence of CRS without nasal polyps did not change according to the place of residence. CRS was generally more common among smokers, but there was no significant difference in patients with CRS accompanied by nasal polyps. CRS was not more common in people with allergies.

Assessment of the orbital structures using computed tomography in healthy adults.

In this study, we retrospectively evaluated the orbital and ocular dimensions using computed tomography (CT) scans in healthy adults. This retrospective study included 302 Turkish adult individuals aged 20-76 years (158 males and 144 females), who underwent paranasal sinus or craniofacial CT due to headache or suspicion of sinusitis, but abnormal orbital or cranial CT findings were not detected. Linear and volumetric measurements of the orbital structures were performed in the sagittal, coronal, and axial planes on CT slices. The volume was estimated in cubic centimeters using the equation of the ellipsoid method. A total of 34 parameters were measured from both eyes of each individual using 14 different anatomical landmarks and analyzed by gender and age. Parameter values of orbital structures in males and females are shown in millimeters or cubic centimeters. In most of the 34 parameters that we evaluated, it was seen that males had statistically significant higher mean values than females (P < 0.05). Also, there was no statistically significant difference between the measurements of right and left orbits. The correlation with age was varied according to the 34 parameters. Interestingly enough, there were no statistically significant differences between the two genders for extraocular muscles thickness (except superior muscles group thickness-SMT) and left optic nerve thickness (LOT) (p > 0.05). The mean right superior muscles group thickness was 5.35 ± 0.85 mm in the male subjects and 4.64 ± 1.10 mm in the female subjects (P < 0.001). The mean left superior muscles group thickness (LSMT) was 5.28 ± 0.88 mm in the male subjects and 4.67 ± 1.16 mm in the female subjects (P < 0.001). The mean LOT was 6.15 ± 0.97 and 5.88 ± 1.07 mm in males and females, respectively (P = 0.099). This study can be applied to the standardization of orbital morphometry in healthy adults.

Nasal Septal Deviation and Incidental Paranasal Sinus Opacification: A Role of Computed Tomography

Background and Objectives: The purpose of this study was to investigate the prevalence of incidental paranasal sinus (PNS) opacification in nasal septal deviation (NSD) using computed tomography (CT) and to identify contributing factors.Subjects and Method: We analyzed 216 patients who underwent septoplasty for the correction of NSD and who underwent preoperative PNS CT. We assessed the prevalence of incidental PNS opacification in these patients and determined the type of NSD according to Mladina classification. We also evaluated whether the direction of NSD affected the presence of PNS opacification on CT, and whether the presence of PNS opacification was associated with other rhinologic symptoms.Results: Of 216 patients with NSD, 86 showed opacified PNS on CT. According to Mladina classification, NSD patients were classified as type I (24.1%), type II (36.1%), type III (20.8%), type IV (5.6%), type V (9.7%), type VI (2.3%), or type VII (1.4%). Patients with type II NSD showed a significantly higher incidence of PNS opacification compared with other types of NSD (p=0.001). However, the direction of NSD did not significantly influence the presence of incidental PNS opacification. Furthermore, regardless of the presence of PNS opacification, there was no significant difference in rhinologic symptoms such as olfactory dysfunction, among others.Conclusion: We found that incidental PNS opacification on CT was common in NSD patients, especially in patients with type II NSD. Thus, we suggest that CT evaluation of patients with NSD may be helpful for assessing comorbid PNS pathologies as well as objectively identifying nasal septal deformities.

Paranasal sinus CT and 3 kinds of nasal endoscopic sphenoid sinus surgical approaches: Retrospective analysis of 128 cases.

Even being equipped with advanced surgical navigation systems, thorough analysis of patient's imaging diagnosis before procedures is still of great necessity for the operators. This study aimed to explore the morphological changes of sphenoid sinus lesions as observed on computed tomography (CT), and further carry out the fenestration of sphenoid sinus under guidance of the CT.A retrospective analysis of the characteristics of CT images was performed. The outcomes of three kinds of nasal endoscopic surgeries on benign lesions of sphenoid sinuses were investigated. For the 128 patients included, nasal-cavity-olfactory cleft pathway was performed in 64 patients, the Messerklinger pathway was adopted in 54 patients, while Wigand pathway was performed in the rest 10 patients.After follow-up visit, the drainage at the fenestration site of sphenoid sinus was found to be smooth, the symptoms were completely controlled, and no severe complication was reported during or after the surgery. No significant difference was observed in the curative effects among the 3 groups.CT of the paranasal sinus can guide the procedures of sphenoid sinus fenestration. No statistically significant differences were exhibited in terms of the amount of bleeding, surgical time and days of hospitalization among the 3 groups.

Thyroid Cancer Risk in Patients Undergoing 64 Slice Brain and Paranasal Sinuses Computed Tomography

Purpose: Computed Tomography (CT) is a fundamental part of diagnosis of diseases. During CT examinations organs in and out of scanned volume are exposed to ionization radiation. The aim of this study was Estimation Thyroid cancer risk in Patients who Underwent 64 Slice brain and paranasal sinuses CT scan. Materials and Methods: with permission from the authors and editor, data related to thyroid dose of 40 patients in Mazyar et al.'s paper was used and by using Biological Effects of Ionizing Radiation (BEIR)VII model thyroid cancer risk was calculated for different ages at exposure in male and female. Results: In both brain and paranasal sinuses CT, ERR values in female patients were twice as many as those in male patients. At age range from 20 to 40 years, ERR was considerably more than at age range 40-60 years since young patients are more radiosensitive than old patients. Conclusion: The calculations of ERR indicate that PNS and brain CT increase the theoretical risk of thyroid cancer incidence. Although the ERR values are low, impacts on the thyroid cancer incidence should not be disregarded.

Computed Tomography Image Analysis and Clinical Correlations of Retromaxillary Cells

This study aimed to investigate and analyze the anatomic characteristics of the retromaxillary cell (RMC) by using computed tomography (CT) images of paranasal sinuses and to improve its identification with ethmomaxillary sinus (EMS). The paranasal sinus CT scans of 441 outpatients or inpatients in our hospital from January 2018 to October 2018 were analyzed. The incidence of RMC, EMS, Haller cell, imaging anatomical characteristics, and morphological manifestations were observed via sinus CTs. The relationship of RMC and ipsilateral maxillary sinusitis was analyzed. The incidence of RMC is 83.90% (740/882). The incidence of males and females was 83.81% (414/494) and 84.02% (326/388), respectively. The incidence of bilateral (72.79%, 321/441) was much higher than that of unilateral (22.22%, 98/441). The lateral extension of the RMC ranged from 1.18 to 13.31 mm, with an average of 6.10 ± 2.03 mm. The incidence of ipsilateral maxillary sinus opacification on the RMC sides and non-RMC sides has no significance difference (χ2 = .054, P = .459). The incidence of Haller cell and EMS decreased significantly in the presence of RMC (P < .01). The RMC is an anatomical variation originating from posterior ethmoid cells, which is commonly encountered in the clinic. The pneumatization of RMC is highly variable, and a bilateral is common. During endoscopic sinus surgery, it is necessary to carefully identify such an air cell to ensure the complete opening of the paranasal sinus during surgery.

The Whole Lateral Type of the Sphenoethmoidal Cell and Its Relevance to Endoscopic Sinus Surgery.

The sphenoethmoidal cell and the sphenoid sinus (SS) show great similarity in endoscopy and imaging. Hence, it is important to accurately identify the sphenoethmoidal cell preoperatively to prevent injury of the nerve and artery during endoscopic surgery. The aim of the present study was to investigate a special type of sphenoethmoidal cell. A total of 365 inpatients whose paranasal sinus computed tomography (CT) was collected and reviewed from May 2018 to September 2019 were included. The anatomical imaging characteristics of the sphenoethmoidal cell were observed. A special type of the sphenoethmoidal cell was found on 9 sides in 730 sides (1.3%), according to its extension to the SS. Unlike Onodi cell (49.6%) and Jinfeng cell (1.3%), this cell simultaneously extends toward the superolateral, lateral, and inferolateral regions of the SS and is simultaneously closely attached to the optic canal and the maxillary nerve. Presently, this cell is named as the whole lateral type of the sphenoethmoidal cell, and the SS is located at the medial or inferomedial of it. When evaluating the paranasal sinus CT preoperatively, attention must be paid to the possibility of the whole lateral type of sphenoethmoidal cell appearing, not just Onodi cell, extending into the SS.

Accessory Maxillary Ostia: Prevalence of an Anatomical Variant and Association with Chronic Sinusitis.

IntroductionThe role of the accessory maxillary ostium, a common anatomical variant, in the development of chronic sinusitis remains unclear. This study aimed to examine the association between chronic sinusitis and presence of an accessory maxillary ostium using computed tomography (CT) of the paranasal sinuses.MethodsWe conducted a retrospective study of 1188 paranasal sinus CT scans performed in a major tertiary medical center between January 1, 2016 and December 31, 2016. Axial and coronal and views were reviewed to evaluate the presence of accessory maxillary ostia and maxillary and ethmoid sinusitis.ResultsNine hundred twenty-eight patients were included for analysis. A 52.8% were male. Mean patient age was 33.8 years. A right accessory maxillary ostium was detected in 274 patients (29.5%), which was the same number of patients with a left accessory maxillary ostium. Bilateral accessory maxillary ostia were found in 172. The presence of right maxillary sinusitis was significantly associated with male gender and the presence of a right accessory maxillary ostium. Male gender was the only factor significantly associated with the presence of left sinusitis. Left or right ethmoidal sinusitis was significantly associated with male gender and the presence of left or right maxillary sinusitis, respectively.ConclusionThe presence of an accessory maxillary ostium may contribute to the development of maxillary and ethmoidal sinusitis. Further studies are needed to elucidate this association and determine indications for incorporating the natural and accessory ostia when performing middle meatus antrostomy during endoscopic sinus surgery.

Impact of Paranasal Sinus Surgery in Granulomatosis With Polyangiitis: A Longitudinal Computed Tomography Study.

Severe chronic rhinosinusitis (CRS) in patients with granulomatosis with polyangiitis (GPA) failing medical therapies can be treated with paranasal sinus surgery. Whether this surgery protects from progressive sinonasal damage remains unknown. Here, we aimed to analyze time-dependent relations between sinus surgeries and computed tomography (CT) imaging features in the CRS of GPA. Longitudinal observational study. We assessed CRS features including bone thickening by global osteitis scoring scale, bone erosions, and mucosal thickening by Lund-Mackay scores in serial paranasal sinus CT scans (742 CT scans in total) from a cohort of 127 well-characterized GPA patients. Data on sinonasal surgical procedures were from a mandatory national registry and from chart review. We defined the time from baseline CT to last CT as the study observation period in each patient. Datasets were analyzed by linear mixed models. We found that 23/127 cohort patients had one or more paranasal sinus surgical procedures, and 96% of these (22/23) had osteitis by CT after surgery. In patients with nasal surgery alone or no surgery, we identified osteitis in 7/11 (64%) and 45/93 (48%), respectively. During the observation period of a median of 5 years, 38 patients had progression of their sinus osteitis, with the highest annual osteitis progression rates observed around the time of surgery. In this cohort, paranasal sinus surgery was associated with prevalence, severity, and progression rate of sinus osteitis, indicating that sinus surgery does not reduce the bone damage development in the CRS of GPA. 4 Laryngoscope, 130: E460-E468, 2020.

Analysis of Lamina Papyracea Area and Ethmoid Sinus Volume in Indonesian Patients Undergoing Paranasal Sinus CT Scan

Of the rhinosinusitis (CRS) patients, half of whom require surgical intervention. Functional endoscopic sinus surgery (FESS) is a standard treatment of CRS and sinonasal polyposis. Orbito-ocular complications can occur during FESS. The lamina papyracea (LP) is the weakest point of the medial wall of the orbit. The variability in the size and shape of the paranasal sinuses is important in the FESS procedure. The ethmoid sinus is the most complex paranasal sinuses. Preoperative evaluation using computed tomography (CT) is mandatory for all patients undergoing FESS. This study aimed to determine the lamina papyracea area and ethmoid sinuses volume in patients who underwent a CT scan of paranasal sinuses. This study was a descriptive study on 103 patients who underwent a CT scan of paranasal sinuses in the Radiology Department of Hasanuddin University General Hospital, Makassar, from January to August 2019. The lamina papyracea area and ethmoid sinus volume were measured based on age and gender. The results showed that the average of lamina papyracea size and ethmoid sinus volume was greater in males than in females. There was a correlation between age and posterior height of left lamina papyracea (p=0.02), but no correlation between ethmoid sinuses volume and age.

Role of Computed Tomography in Determining the Spectrum of Paranasal Sinuses Pathologies in Saudi patients

Background and Objective: Now-a-days computed tomography (CT) has become the investigation of choice for the diagnosis of the paranasal sinuses (PNS) pathologies. This study was designed with an aim to determine the role of computed tomography in classification the spectrum of PNS pathologies in Saudi patients. Materials and Methods: A total of 100 PNS CT patients were prospectively examined during the period extending from October 2018 to October 2019. A 128 detector CT scanner (Workstation Intellispace ISP; Philips, Netherlands), was applied to investigate patients with suspected PNS abnormalities at Radiology and Medical Imaging Department at King Khalid Hospital and Prince Sultan Center for Health Services in Al-Kharj, Saudi Arabia. Results: Out of the 100 patients – 56% males and 44% females with male to female ratio of 1.3:1 – Maxillary sinuses were the most sinuses that affected by sinusitis (68%) and the frontal sinuses was the last one (30%). The most common pathology seen was sinusitis in 79% cases. Atrophy, polyp and hypoplastic disease were detected in (1%) of cases. Most common anatomical variations were closed osteomeatal complex (86%), inferior nasal turbinates muscle hypertrophy (54%) and deviated nasal septum (83%). Conclusion: The CT was able to characterize the PNS diseases along with their extension. The most common pathology was sinusitis with 68, 55, 35 and 30% in the maxillary, ethmoid, sphenoid and frontal sinuses, respectively. Most common anatomical variant seen was nasal septum defect while the most commonly sinus involved was maxillary. It proves the better sensitivity (98.04%), specificity (80%) and accuracy (97.02%) of CT in the evaluation of various sinonasal pathologies.

Olfactory Cleft Width and Volume: Possible Risk Factors for Postinfectious Olfactory Dysfunction.

Upper respiratory tract infections are a common cause of temporary and permanent olfactory dysfunction in the general population. Postviral or postinfectious olfactory loss (PIOL) develops only in rare cases. The aim of this study was to investigate the anatomical features of olfactory cleft (OC) in patients with PIOL to shed light on possible predisposing factors for PIOL. Retrospective study. We retrospectively evaluated paranasal sinus computed tomography (CT) scan results of patients diagnosed with PIOL. A control group consisted of normosmic individuals who underwent paranasal sinus CT scans before septoplasty surgery. We compared the olfactory fossa depth, OC width, and volume on the CT scans of the PIOL and control groups. In total, 71 individuals fulfilled the study criteria (PIOL group, n = 32; control group, n = 39). There was no statistically significant difference in the olfactory fossa depth in the two groups. The OC width and volume in the PIOL group was found to be significantly increased than that in the control group (P < .001 for both). Patients with PIOL had increased OC width and volume than the healthy controls. An extra-wide olfactory cleft may be a predisposing factor in the pathogenesis of PIOL. 4 Laryngoscope, 131:5-9, 2021.

Sino-Nasal Anatomical Variations in Rhinogenic Headache Pathogenesis.

Rhinogenic headache (RH) is a widespread pain syndrome but its pathogenesis and treatment are still unclear. Some authors recognize a correlation between RH and mucosal contact points or some other sinonasal anatomical variations. The authors conducted a retrospective case-control study to analyze the correlation between radiological findings and clinical symptoms.One hundred-nineteen adults with Para-Nasal Sinuses Computed Tomography (PNS-CT) scans were included: 64 patients who have originally undergone PNS-CT scan as part of rhinogenic headache workup (Group A), and 55 controls in whom PNS-CT scans were obtained for other purposes (Group B). All subjects were asked to report their symptoms using a headache scoring system. PNS-CT scans of all subjects were analyzed for presence of mucosal contact points, middle turbinate concha bullosa (MTCB) and frontoethmoidal cells.The most common anatomical abnormality found in our series was MTCB, reported in 60.9% of patients in Group A and 41.8% of those in Group B. A statistically significant prevalence was found in Group A compared to Group B regarding the presence of MTCB (P = 0.037) and Type II (P = 0.016) and Type III (P = 0.039) frontoethmoidal cells. No statistically significant difference (P >0.05) was found between Group A and Group B regarding the presence of mucosal contact points at each site.Multiple anatomical variations in nasal and paranasal sinuses may cause a rhinogenic headache with different characteristics. Some of these, such as concha bullosa of middle turbinate or type II and III Kuhn cells, have shown a significant association with rhinogenic headache. No statistically significant association was found between presence of headache and mucosal contact points and type I and IV frontal cells. These findings can be very helpful for the surgeons that want to deal with the treatment of RH.

Is there a relationship between Onodi cell and optic canal?

We investigated the relationship between Onodi cells and optic canal by paranasal sinus computed tomography (PNSCT). In this retrospective study, 508 PNSCT (265 males and 243 females) was examined. Onodi cell presence, pneumatization types, optic canal types; and also sphenoid sinusitis and anterior clinoid process pneumatization were evaluated. The prevalence of Onodi cells was 21.2% of the patients. Onodi cells were observed 40.7% on the right side and 25.9% on the left side. In 33.4% of the patients, bilateral Onodi cells were present. Male/Female ratio was 24.5%/17.6%. Onodi cell types were detected as Type I > Type II > Type III bilaterally. There was a positive correlation between the right and left Onodi cell types (p < 0.05). Optic canal types were detected as Type IV > Type I > Type II > Type III. bilaterally. There was a positive correlation between right and left optic canal types. Onodi cell presence and ACP pneumatization were found as statistically significant (p < 0.05). In 65.5% of the patients, Onodi cells and ACP pneumatization were absent. ACP pneumatization was present in 35.4% of the cases. In nine cases, bilateral Onodi cells and ACP pneumatization were detected. Sphenoid sinusitis was detected in 11.4% of Type I and 13.8% of the Type II Onodi cells on the right side. On the left side, it was detected in 12.9% of the Type I and 19.0% of Type II Onodi cells. Identification of Onodi cell is very important clinically because of its proximity to optic nerve canal. We concluded that type IV Onodi-optic canal relationship was the most common finding in our study. Onodi cell presence and their patterns of pneumatization must be evaluated on PNSCT preoperatively to avoid optic canal damage.

Image Optimization and reduction of radiation dose in CT of the paranasal sinuses

Introduction: Since demand for computed tomography (CT) examinations is growing, patients are exposed more frequently to ionizing radiation. To reduce the dose delivered to patients in each scan, CT technologists can change the image acquisition parameters. However, this reduces image quality. Present study aimed to optimize and reduce radiation dose in a CT of the paranasal sinuses while minimizing deterioration of image quality Materials and Methods: We divided the patients into two study groups: Group A was scanned axially and coronally using default parameters, while Group B was scanned axially and coronally using new parameters. The patients’ organ doses were estimated using the ImpactDose calculator. The tube voltage, tube current, pitch, rotation time, and other parameters were then reduced and optimized. After reconstruction and analysis, all of the images were of good diagnostic quality in both groups Results: Using the new parameters, good agreement was found between the direct and reconstructed images. The CT parameters were reduced by the following proportions: kVp— 16.6%, mA—75%, rotation time—20%, and mAs—80%. However, these reductions did not obscure any anatomical landmarks. These parameters reduced the CTDIw, CTDIvol and DLP by 88.2%, 91.3%, and 91.3% respectively. Conclusion: In conclusion, the results suggest that the use of a Bone algorithm reduces the total amount of radiation used during CT of the sinuses. We recommend using these parameters in children, in the evaluation of facial trauma, and in emergency CT of the paranasal sinuses

Investigation of Distances Between the Anterior Nasal Spine and Nasofrontal Beak, Basal Lamella, Skull Base, and Sphenoid Sinus on Paranasal Sinus Computed Tomography.

The aim of this study was to investigate the distances between the anterior nasal spine and basal lamella (BL), skull base, nasofrontal beak (NfB), and the anterior wall of sphenoid sinus on computed tomography (CT) images. A total of 160 patients who were seen at the otolaryngology clinic of our institution were evaluated with the help of the image processing software of the radiology department. Cases in which bony structures could not be seen clearly because of previous surgery or trauma were excluded. The distance between the anterior nasal spine; and NfB, the closest point of the skull base in the frontal recess (SB1), the closest point of the BL, the intersection of the line with which the distance to the BL was measured with the skull base (SB2) and the closest point of the anterior wall of the sphenoid sinus (Sp) were measured using multiplanar reconstruction. The images of 140 patients were examined. NfB, SB1, BL, SB2, and Sp were 5.14 ± 0.46 (4.15-6.38) cm, 5.70 ± 0.48 (4.31-7.03) cm, 4.84 ± 0.44 (3.86-5.98) cm, 6.23 ± 0.50 (5.13-7.35) cm, and 6.14 ± 0.46 (5.04-7.36) cm, respectively. In our study group, the distances some of which were reported as constant values in the literature were found to have a range of up to 2 cm. Therefore, if distances between structures are to be used for orientation during endoscopic sinus surgery, they should be better measured preoperatively on paranasal sinus CT scan images instead of using predefined constant values.

Olfactory fossa depth: CT analysis of 1200 patients

Background:Olfactory fossa (OF) is a depression in anterior cranial cavity whose floor is formed by cribriform plate of ethmoid. Lateral lamella, which forms its lateral boundary, is a thin plate of bone and is at risk of injury during functional endoscopic sinus surgery, especially when fossa is deep/asymmetric.Aims:To measure the variations in the depth of OF and categorize Kerala population as per Keros classification using computed tomography (CT).Settings and Design:This study was conducted in our institution from January 2016 to August 2017. Patients >16 years of age undergoing CT scan of paranasal sinuses (PNS) were included.Materials and Methods:Coronal PNS CT scan studies of 1200 patients were reviewed. The depth of OF was measured from vertical height of lateral lamella.Statistical Methods:Results were analyzed according to gender and laterality using independent sample t-test and Chi-square test.Results:The mean depth of OF was 5.26 ± 1.69 mm. Statistically significant difference was seen in the mean depth of OF between males and females but not between right and left sides. Keros type I was found on 420 sides (17.5%), type II in 1790 (74.6%), and type III on 190 sides (7.9%). Type III Keros was more on the right (9%) than left (6.8%) side, more in males (9.5%) than females (5.9%), and more among males on the right side (11.4%). Asymmetry in OF depth between two sides was seen in 75% of subjects.Conclusion:Prevalence of the dangerous type III OF, even though low, is significant especially among males and on the right side. Therefore, preoperative assessment of OF depth must be done to reduce iatrogenic complications.

Carotid canal and optic canal at sphenoid sinus.

In the present study, we investigated the relationship between sphenoid sinus, carotid canal, and optic canal on paranasal sinus computed tomography (PNSCT). This study was performed retrospectively. PNSCT images of 300 adult subjects (159 male, 141 female). Sphenoid sinus (pneumatisation, dominancy, septation, inter-sinus septa deviation), anterior clinoid process pneumatisation, Onodi cell, carotid and optic canals (width, dehiscence, classification) were measured. In males, type 3 pneumatised sphenoid sinus (in both sides) and in females type 2 pneumatised sphenoid sinus (right side) and type 3 pneumatised sphenoid sinus (left side) were detected more. Anterior clinoid pneumatisation was present 47.2% in males and 39.7% in females. In male group, more septation (i.e. 22.6%, ≥ 3 septa) in sphenoid sinus were detected. Onodi cell was present 26.6 and 19.1% in males and females, respectively. Carotid canal protrudation to the sphenoid sinus wall was present 23.9-32.1% in males and 35.5-36.2% in females. Dehiscence in carotid canal was detected more in females (34%) compared to males (22%). Optic canal protrudation was 33.3 and 30.5% in males and females. Type 4 optic canal was detected more in both gender. Optic canal dehiscence was detected 11.3 and 9.9% in males and females. Carotid and optic canal diameters were higher in males. In pneumatised sphenoid sinuses and in females, type 3 carotid canal (Protrudation to SS wall) (bilaterally) and type 1 optic canal type (No indentation) (ipsilateral side) were detected more. In elderly patients, carotid and optic canal width increased. When carotid canal protrudation was detected, there was no indentation in optic canals In pneumatised SS, carotid canal protrudation was observed with a greater risk in surgery. However, type 1 (non indentation) optic canal was present in highly pneumatised SS with lower risk for the surgery. In women, the risk of carotid canal protruding (about 1/3) is greater than that of males, and carotid canal dehiscence rates are also higher in females. Therefore, physicians should be very careful during the preparatory stages of the sphenoid sinus surgery. Otherwise, it may not be possible to prevent lethal carotid artery bleeds.