Role of Multi-Detector CT in Paranasal Sinuses

SUMMARY OF THESIS

Name of speciality : Radio-diagnosis

Name of System : Head and Neck

Title of Thesis and : Role of Multi-Detector Computed Tomography in Paranasal Sinuses Pathology, 2015.

• Lakshmi Kumar Chalamarla

Name of Supervisor : Dr. Kavita Kapoor, Consultant

Imaging, Batra Hospital and Medical Research Centre, New Delhi.

Hospital/Institute : Batra Hospital and Medical Research Centre, New Delhi-110062.

AIMS AND OBJECTIVES

1. To characterize pathologies of paranasal sinuses on MDCT and to delineate their anatomical location, extension and bony involvement.
2. To correlate the multi detector computed tomography findings with clinical/surgical/histopathological/ microbiological findings.

MATERIAL AND METHODS

STUDY AREA:

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. Other departments are collaborated for acquiring cases, and follow up of patients to correlate clinically or histopathologically or microbiologically.

STUDY POPULATION:

100 patients were included in our study mostly urban population. Patients belonged to both OPD and IPD cases. The study comprised of 65 males and 35 females. The number of male patients were higher than the female patients. 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.

SAMPLE SIZE:

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 from 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:

1. Acute sinonasal inflammatory disease.
2. Previous evidence of sinonasal surgery.
3. All cases of trauma.

SAMPLE SIZE CALCULATION:

(Ref.: Methods in biostatistics, Dr. B. K. Mahajan, 7^th edition, pg. 85)

For calculation of sample size Mahajan’s allowable error formula was applied.

N = 4pq/e²

Where p = % of population = Target population/Total population×100

q = 1-p

e = 20% of p

As per CT room register over last 3 years

Minimum no. of MDCT PNS cases at our hospital/month = 20

Maximum no. of MDCT PNS cases coming under exclusion criteria/month = 5

So,

Minimum no. of MDCT PNS cases at our hospital/year = 240

Maximum no. of cases coming under exclusion criteria/year = 60

So, p = 180/240×100 = 75

q = 25

e = 20% of p = 15

N = 4×75×25/15² = 33.

The minimum sample size thus calculated should be 33.

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.

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

PROFORMA

Unique ID No:

HISTORY:

Presenting Complaints:

Nasal discharge: Headache:

Nasal obstruction: Epistaxis:

Swelling over cheek: Hyposmia/Anosmia:

Others:

H/O Smoking:

Occupational exposure:

History of Allergy:

Any other Systemic Illness:

Family History:

EXAMINATION:

General Examination:

Local Examination:

Inspection:

Probe test:

Others:

Important Surgical Findings:

Investigational Results:

MDCT PNS :

Histopathology:

Microbiological and other important lab tests:

Department of Radio-diagnosis and Imaging

Batra Hospital and Medical research Centre

M.B.Road, New Delhi-110062.

INFORMED CONSENT FORM

I s/d/w of r/o

do hereby declare that I give informed consent to participate in the thesis study titled, “ROLE OF MULTI-DETECTOR COMPUTED TOMOGRAPHY IN PARANASAL SINUSES PATHOLOGY”.

Dr. Lakshmi Kumar Chalamarla has informed me to my full satisfaction, in the language understand, about the purpose, nature of study and various investigations to be carried out for the study. I have been informed about the duration of the study and the possible benefits and risks.

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I give full, free and voluntary consent for being enrolled in the above study and reserve the right to withdraw from the study whenever I wish to without any prejudice of my right to undergo further treatment at this hospital and its associated hospitals. I have been given a copy of this form along with the patient information sheet.

For illiterates patient information sheet will be shared with the family members. The family members are expected to read out and then get the informed consent. We will try to take written consent, if not we will take verbal consent in front of relatives.

(Signature/Thumb (Signature/Thumb

Impression of patient) Impression of relative)

Name: Name:

Date: Relation:

Verbal Consent: Date:

PATIENT INFORMATION SHEET

Title: ROLE OF MULTI-DETECTOR COMPUTED TOMOGRAPHY IN PARANASAL SINUSES PATHOLOGY.

Introduction: This statement describes the purpose, procedures, benefits, risks and discomforts of the study and your right to withdraw from the study at any point of time.

Purpose: This study involves MDCT scan evaluation of patients with paranasal sinus complaints.

Study Procedure: Your relevant clinical history will be recorded, clinical examination will be conducted and findings noted. MDCT PNS will be performed and the radiological findings will be recorded. These findings are correlated with clinical/surgical/histopathological/microbiological findings.

Benefits: No monetary benefits will be given to you. However, any new information that can come to light regarding any new findings in the study will help in further management of the disease and help all other ailing patients suffering from this problem.

Confidentiality: Records of your study participation will be kept confidential, under safe custody. Any publication of data will not identify you by name. By signing the consent form you authorise the sharing of your study related medical records to the regulatory authorities and the Institutional Ethical Committee.

Information regarding withdrawal: You have the right to withdraw yourself from the study at any time during the course of the study without any prejudice to you or your family’s right to undergo future treatment at BATRA HOSPITAL.

Contact for additional information: Any time during or after the study, you can obtain further information about the study from Dr. Lakshmi Kumar Chalamarla, Department of Radio-diagnosis, BHMRC, New Delhi.

DATA ANALYSIS

Sensitivity, specificity, positive predictive value and negative predictive values were calculated, followed by use of Fischer Exact test. Diagnostic accuracy of MDCT for different pathologies were calculated

The research hypothesis and statistical methods were formed in consultation with the Biostatistician.

SALIENT FINDINGS

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.

The patients were divided into five categories: bacterial sinusitis, fungal sinusitis, benign tumors, malignant tumors, and others. 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 conditions.

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.

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 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, 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 3 cases. Bone thickening/sclerosis, and calcification were not seen in any of the cases.

In our study we found sensitivity and specificity for bacterial sinusitis as 100% and 94.11% respectively. The fungal sinusitis had sensitivity an 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 others 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 with respect to anatomical delineation, 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.

CONCLUSIONS

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 modality of all imaging studies available because of its ease, availability, accuracy, precision and low cost.