Pathologies of Paranasal Sinuses on MDCT

Pathologies of Paranasal Sinuses on MDCT MATERIAL AND METHODS The study was conducted at the Department of Radio-diagnosis and Imaging in collaboration with the Department of ENT, Department of Pathology, and Department of Microbiology, Batra Hospital and Medical Research Centre. STUDY DESIGN: Observational study. CT PNS of the patients was evaluated for the cause of sinus complaints. Causes deduced from CT PNS were correlated with clinical/histopathological/surgical/ microbiological findings. STATISTICAL METHODS: Sensitivity, specificity, positive predictive value and negative predictive value were calculated, followed by use of Fischer Exact test. The research hypothesis and statistical methods were formed in consultation with the Biostatistician. SAMPLE SIZE (Annexure 6): 100 patients referred for evaluation of sinus complaints were enrolled in the study after fulfilling the inclusion and exclusion criteria and taking written/verbal informed consent, over a period of July 2013 to April 2015. INCLUSION CRITERIA: Patients with complaints like headache/nasal obstruction/discharge/hyposmia /swelling over cheek and with clinically suspected paranasal sinuses lesions referred for MDCT PNS evaluation. EXCLUSION CRITERIA: Acute sinonasal inflammatory disease. Previous evidence of sinonasal surgery. All cases of trauma. ETHICAL ISSUES: The study was conducted after necessary approval from the Institutional review board and ethics committee. MDCT is a non-invasive modality. All safety and screening measures were undertaken as per the American College of Radiology practice guidelines for performing Computed Tomography. INSTRUMENTATION: Light VCT 64 slice MDCT of GE radical system with advanced workstation 4.3 GE. Protocol followed for MDCT PNS: 1. Scout : Lateral kV : 120 mA : 10 Scout Plane : 900 2. Axial Images kV : 120 mA : 120 Start/End : 0 to 74.3 Total Exposure Time : 5.4 sec Gantry tilt : 0 Interval : 0.625 mm Slice thickness : 0.625 mm Helical Scan Rotation Time : 0.6 sec Rotation Length : Full Pitch and Speed : 0.531:1 10.62 mm/rotation Detector Coverage : 20 mm SUMMARY The present study was conducted in Department of Radiodiagnosis, Batra hospital and medical research centre, New Delhi in close association with the department of ENT from July 2013 to April 2015. The aims and objectives of our study were to characterize pathologies of paranasal sinuses on MDCT, to delineate their anatomical location, extension and bony involvement and to correlate the multi detector computed tomography findings with clinical/surgical/histopathological/ microbiological findings. A total of 100 patients who came with complaints referring to nose and paranasal sinuses were included in the study. All patients were subjected to MDCT PNS after detailed clinical examination. The imaging findings are correlated with other investigations. Key imaging features considered were significant anatomical variations, site of involvement, bony and soft tissue changes, invasion of surrounding structures, pathognomic features and correlation with clinical complaints/surgical/pathological/microbiological findings. Among 100 patients in our study, there were 15 patients in 0 20 years age group, 36 patients in 21 40 years age group, 37 in 41 60 years age group and 12 were greater than 60 years. The age group of patients ranged from minimum of 9 months to maximum of 81 years. The highest number of patients were in 41 60 years age group. The study comprised of 65 males and 35 females. The number of male patients were higher than the female patients. The patients were divided into five categories: bacterial sinusitis, fungal sinusitis, benign tumors, malignant tumors, and miscellaneous. 84 patients presented with sub acute or chronic bacterial sinusitis, 4 patients were of fungal sinusitis, 4 patients presented with benign tumors, 3 patients with malignant tumors and 5 patients with other miscellaneous conditions. Various anatomical variations were encountered during our study. One or the other anatomic variation was found in 99 cases ( 99% ). Of the structures around ostiomeatal unit, giant bulla ethmoidalis was found in 35 cases, middle turbinate pneumatisation in 33 cases, paradoxical curvature of middle turbinate in 19 cases. Haller cell was found in 15 cases. Type 1 frontal sinus drainage pathway in 78 cases, type 2 frontal sinus drainage pathway in 21 cases. Deviated nasal septum with or without septal spur in 55 cases, inferior turbinate hypertrophy in 30 cases, accessory maxillary ostia in 26 cases, and agger nasi cell in 93 cases. Type 1 optic nerve course was found in 53 cases, type 2 in 14 cases, type 3 in 9 cases, and type 4 optic nerve course along with Onodi cells in 23 cases. Type 1 anterior clinoid process pneumatisation was found in 10 cases, type 2 pneumatisation in 1 case. Sphenoid septum lateral attachment in 7 cases, and sphenoid sinus septum pneumatisation in 14 cases. Among 84 patients with bacterial sinusitis, 26 patients presented with sporadic pattern, 23 patients with infundibular pattern, 23 patients with ostiomeatal unit pattern, 8 patients with polyposis pattern, and 4 patients with sphenoid recess pattern. The various causative factors which came across in infundibular pattern were Haller cells in 6 cases, giant bulla ethmoidalis in 6 cases, uncinate process pneumatisation in 1 case, and mucoperiosteal thickening in 10 cases. The various causative factors for ostiomeatal pattern which were found during our study were: inferior turbinate hypertrophy in 6 cases, giant bulla ethmoidalis in 6 cases, deviated nasal septum with or without septal spur in 4 cases, concha bullosa in 3 cases, concha lamella in 2 cases, agger nasi cell in 1 case, and paradoxical middle turbinate in 1 case. The various findings which were encountered in bacterial sinusitis in our study were: mucoperiosteal thickening in 84 cases, ostiomeatal unit block in 31 patients, bone thickening in 20 patients, bone thinning in 8 cases, and bone sclerosis in 6 patients. Among 4 patients with fungal sinusitis, the various findings were: bilateral / multisinus involvement was found in 4 cases, expansion of any involved sinus was found in 4 cases, intrasinus hyperdensity was found in 4 cases. Bony thinning was found in 4 cases, bony erosions and nasal cavity involvement was found in 3 cases. The various findings in 4 cases of benign tumors seen ( 1 inverted papilloma, 1 juvenile angiofibroma and 2 ivory osteomas ) were: bony thinning in 2 cases, bony remodelling in 2 cases, multisinus involvement in 2 cases, intracranial extension in 1 case, and intra orbital extension in 1 case. Bony destruction, bone thickening/sclerosis, and calcification were not seen in any of the cases. Among 3 cases of malignant tumors (squamous cell carcinoma, embryonal rhabdomyosarcoma, and esthesioneuroblastoma), various findings were: : Bony destruction in 3 cases, bony thinning in 3 cases, bony remodelling in 0 cases, multisinus involvement in 2 cases, intracranial extension in 2 cases, and intra orbital extension in 2 cases. Bone thickening/sclerosis, and calcification were not seen in any of the cases. Under miscellaneous category we encountered one case each of periapical cyst, oro-antral fistula, granulomatous polyangitis, monostotic fibrous dysplasia, and Langerhans cell histiocytosis. In our study we found sensitivity and specificity for bacterial sinusitis as 100% and 94.11% respectively. The fungal sinusitis had sensitivity and specificity of 75% and 100% respectively. Benign, malignant tumors and others had sensitivity and specificity of 100%. The diagnostic accuracy for bacterial sinusitis and fungal sinusitis was 99%, and the diagnostic accuracy of benign, malignant tumors and other miscellaneous conditions was 100%. The p value was obtained after applying Fischer Exact test. The p value obtained was statistically significant for all the disease conditions. Based on the statistical values it can be inferred that multi detector computed tomography is useful to characterize paranasal sinuses lesions and also delineation of anatomical location, extension and bony involvement. There are certain limitations in our study. Our findings cannot be generalised to the whole population because of the limited sample size. However, our findings add value to the research done. The role of contrast cannot be adequately studied. The role of MRI in various paranasal sinus pathologies was not evaluated. CONCLUSION Paranasal sinus diseases are very commonly encountered problems in clinical practice. Clinical assessment alone is not sufficient to reach a diagnosis, as the presentation of most of the conditions is nonspecific. Imaging forms the mainstay not only in making correct diagnosis, but also to know the extent of lesion, pre-operative assessment of the sinonasal anatomy and commonly encountered anatomic variations. X ray has low sensitivity, specificity, positive and negative predictive values. CT is highly sensitive and specific in determining the presence of paranasal sinus pathology and clearly demonstrates the complex anatomy. The introduction of multi detector CT has transformed the axial imaging modality into a volumetric one and allows the pathology to be displayed in any desired plane. The capability of thin-section acquisition improves visualisation of tiny pathological details, and the isotropic nature of high spatial resolution data sets enables display in multiple planes, obviating image acquisition in prone or hyper extended patient position. Recommendations: 1. MDCT has proved to be highly sensitive in classifying the lesions into clinically relevant categories, making diagnosis and more so in knowing the extent of involvement with a high diagnostic accuracy. 2. MDCT is an indispensible tool before Functional Endoscopic Sinus Surgery (FESS) to accurately delineate the fine bony details that contribute to disease and also can predispose to complications which can be fatal. 3. MDCT is very useful in predicting the diagnosis of fungal sinusitis by the presence of intrasinus hyperdensity, granulomatous diseases by the presence of nasal septal perforation and intracranial or intraorbital invasion, malignancy by bone destruction and invasion. 4. MDCT can tailor the surgery according to the extent of disease. It helps in determining the prognosis of the malignant tumors depending on the site and extent of the disease. It can also obviate the need for surgery in certain conditions like polyposis. 5. MRI can be problem solving tool in differentiating inflammatory sinonasal diseases from tumors, and also for the presence of intracranial or intraorbital extension. 6. However, MRI alone cannot be performed in the evaluation of paranasal sinus diseases because of the problem of signal voids. It has to be supplemented by CT. 7. MDCT is the preferred initial modality of all imaging studies available because of its ease, availability, accuracy, precision and low cost. 1