A COMPARATIVE STUDY BETWEEN COMPUTED TOMOGRAPHY AND MAGNETIC RESONANCE IMAGING IN THE DIAGNOSIS OF BRAIN TUMOR (USING NATIONAL HOSPITAL, ABUJA AS CASE STUDY)

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LIST OF TABLES

 

Table 1: CT findings of the patient

Table 2:  MRI findings of the patient

Table 3: Biopsy findings of the patient

Table 4: Comparison between CT findings and MRI findings

Table 5:Chi-square test of Comparison between CT findings and MRI findings

Table 6: Comparison between biopsy findings and CT findings

Table 7: Comparison between biopsy findings and MRI findings

Table 8: Comparison of accuracy, sensitivity and specificity of MRI

and CT findings using biopsy as goal standard.

 

 

 

ABSTRACT

This study sought to equip clinician’s on the imaging modality of choice between CT and MRI in the diagnosis of brain tumor. The comparison of the two imaging modalities was accessed using biopsy as goal standard. This research study involved 40 patients who underwent CT, MRI and biopsy one at a time in National hospital, Abuja. Data were collected via secondary source using patient’s folder; hospital records. The result revealed that MRI which has an accuracy, sensitivity and specificity of 67.5%, 65.22% and 70.65% respectively is more accurate than CT which had a sensitivity and specificity of 15%, 13.04% and 17.65% respectively in the diagnosis of brain tumour. Knowledge of the clinician on which modality of choice to use is evaluated.

 

 

TABLE CONTENT

Title page  …………………………………………………………….i

Approval page  ……………………………………………………….ii

Certification  ………………………………………………………….iii

Dedication  ……………………………………………………………iv

Acknowledge  …………………………………………………………v

List of tables  ………………………………………………………….vi

Abstract  ………………………………………………………………vii

Table of content  ………………………………………………………viii

 

Chapter One

1.1 Introduction  ……………………………………………………….1

1.2 Statement of problem  ……………………………………………..3

1.3 General objective  ………………………………………………….3

1.4 Specific objective  ………………………………………………….3

1.5 Hypothesis  ………………………………………………………….3

1.6 Significance of study  ………………………………………………4

1.7 Scope of study  ……………………………………………………..4

1.8 Literature review  ……………………………………………………4

 

Chapter Two 

2.1 CT and its principles of operation  ……………………………….12

2.2 MRI and its principles of operation  ………………………………13

2.3 Anatomy and physiology of the brain  ……………………………15

2.4 Pathophysiology of brain tumuor ………………………………….19

2.5 Conditions that mimic Brain tumour  ……………………………..19

2.6 Cause, symptoms and types of Brain tumour  ……………………20

2.7 How CT of the brain is done and clinical presentation of Brain

tumour on CT radiograph  ……………………………………….24

 

2.8 How MRI of the brain is done and clinical presentation of

 

Brain tumour MRI radiograph  ………………………………………….26

 

Chapter Three

3.0 Design of the study  ……………………………………………………….29

3.2 Population  …………………………………………………………………29

3.2.1 Area of study  …………………………………………………………….29

3.2.2 Target population  ………………………………………………………..29

3.2.3 Subject selection criteria  ………………………………………………….29

3.3 Method of data collection  …………………………………………………..30

3.3.1 Equipments  ………………………………………………………………..30

3.3.2 Procedure for data collection  ………………………………………………30

3.4 Data analysis …………………………………………………………………..31

Chapter Four:

 

Data Presentation  …………………………………………………………………32

 

Chapter five: Discussion, Recommendations,

Summary of Findings and Conclusion

 

5.1 Discussion  …………………………………………………………………….37

5.2 Summary of findings  …………………………………………………………41

5.3 Recommendations  …………………………………………………………….42

5.4 Conclusion ……………………………………………………………………..42

5.5 Areas of further studies  ……………………………………………………….43

5.6 Limitations of the study  ……………………………………………………….43

References

Appendix

 

 

 

 

CHAPTER ONE

 

1.1   INTRODUCTION

Brain tumours are abnormal and uncontrolled proliferation of cells1. Some originate in the brain itself, in which they are termed primary. Others spread to this location from somewhere else in the body through metastases and are termed secondary. Primary brain tumours do not spread to other body sites, and can be malignant or benign. Secondary brain tumours are always malignant. Because the space inside the skull is limited, their growth increase intracranial pressure, and may, cause edema, reduced blood flow, and displacement with consequent degeneration, of healthy tissue that controls vital function.2

Any brain tumor is inherently serious and life-threatening because of its invasive and infiltrative character in the limited space of the intracranial cavity3. However, brain tumors (even malignant ones) are not invariably fatal, especially lipomas which are inherently benign. Brain tumors or intracranial neoplasms can be cancerous (malignant) or non-cancerous (benign); however, the definitions of malignant or benign neoplasms differ from those commonly used in other types of cancerous or non-cancerous neoplasms in the body. Its threat level depends on the combination of factors like the type of tumor, its location, its size and its state of development. Because the brain is well protected by the skull, the early detection of a brain tumor only occurs when diagnostic tools are directed at the intracranial cavity. Usually detection occurs in advanced stages when the presence of the tumor has caused unexplained symptoms.

A good evaluation of the patient with a suspected brain tumour needs a complete history, exact physical examinations especially neurologic ones, and suitable diagnostic neuroimaging studies. The differential diagnosis of patients with signs and symptoms of brain tumours includes both neoplastic and non-neoplastic conditions.4

Computed tomography is the most widespread diagnostic tool for the localization and staging of brain tumour. It has an advantage of being widely available. Computed tomography is faster than magnetic resonance imaging making it study of choice in cases of trauma and emergencies.

MRI provides detailed info about brain tumour anatomy, cellular structure and vascular supply, making it an important tool for effective diagnosis, treatment and monitoring of brain tumour5. MRI does not use ionizing radiation, and thus preferred over CT in patient requiring multiple imaging examinations.

 

 

 

 

1.2     STATEMENT OF PROBLEM

Most patients undergo both the CT and MRI as radiological investigation for the diagnosis of brain tumour. This however could be prevented if the referring clinician knew which modality is better in terms of diagnostic quality.

 

1.3     GENERAL OBJECTIVE

The aim of this study is to compare the diagnostic quality of computed tomography and magnetic resonance imaging.

 

  • SPECIFIC OBJECTIVES
  • To determine which imaging modality best demonstrates the brain tumour –computed tomography and magnetic resonance imaging.
  • To determine which imaging modality is more sensitive in the diagnosis of brain tumour computed tomography and magnetic resonance imaging.
  • To determine which imaging modality is more specific in the diagnosis of brain tumour –computed tomography and magnetic resonance imaging.

 

1.5     SIGINIFICANCE OF STUDY

  • This study will help us to know the imaging modality that is more accurate in the management and diagnosis of brain tumour.
  • This study will eliminate any additional test the patient will undergo to obtain final diagnosis so as to minimize cost and the stay of patient in the hospital.
  • This study will aid in minimizing radiation to patient and radiation safety of the radiographers can be improved, since only the right examination will be carried out.

 

1.6 HYPOTHESIS

There is no difference between CT and MRI in the diagnosis of brain tumour.

 

1.7 SCOPE OF STUDY

This study involves patients who had both, CT and MRI in the diagnosis of brain tumour at National hospital, Abuja.

 

1.8LITRATURE REVIEW

Some literatures on the comparative studies between computed tomography and magnetic resonance imaging are as follows;

R P et al(2000)[6] carried out a research to establish whether radiation treatment planning using MRI alone could replace CT based planning for brain tumour while retaining dosimetry accuracy. In this study, twenty five patients with brain tumours were scanned on a spiral CT scanner and 1.5T MRI scanner .Three treatment plans were generated for all patients. The first plan was generated using the CT scan images with inhomogeneity correction, the second plan used the CT scan without inhomogeneity correction and the third plan used was generated using the MRI scans. The maximum distortion in MRI phantom study was less than 1mm.there were no statistically significant differences in any of the target coverage parameters analyzed in this study. Similarly, the maximum antero-posterior and lateral dimensions for the CT based and MRI based planning did not show any statistical difference. They concluded that MRI based treatment planning for brain tumour is feasible and gives equivalent dosimetric results compared to CT based treatment planning.

Herbert H. Engelhard et al(2003)[7] conducted a prospective study comparing CT and MRI in their ability to diagnose oligodendroglioma. They found that CT scan, oligodendroglioma appears hypodense (57% to 70%) or isodense (61%) and that CT show calcium deposit better than plain films or MRI.  On MRI, an oligodendroglioma is typically hypointense on T1-weighted images and hyperintense on T2-weighted images. They concluded that MRI is more sensitive than CT demonstrating   oligodendroglioma.

Medina et al(1997)[8] found in a retrospective study of three hundred and fifteen pediatric patients that over all MR imaging was more sensitive and specific than CT in detecting intracranial space occupying lesions. (92% and 99%, respectively for MRI versus 81% and 92% respectively for CT).

Davis et al(1991)[9] compared imaging studies in twenty three patients comparing contrast-enhanced MRI with double dose-delayed CT. contrast-enhanced MRI demonstrated more than sixty seven definite or typical brain metastases. The double dose-delayed CT revealed only thirty seven metastatic lesions. The authors concluded that MRI with enhancement is superior to double dose-delayed CT scan for detecting brain metastasis.

Golfieri et al(1991)[10] studied forty four patients with small cell carcinoma to detect cerebral metastases. All patients were studied with contrast enhanced CT scan and gadolinium enhanced MRI. Of all patients, forty three% had cerebral metastases. Both contrast enhanced CT scan and gadolinium enhanced MRI detected greater than 2cm. for lesions less than 2cm, 9% were detected only by gadolinium enhanced T1-weighted images. The authors concluded that gadolinium enhanced T1-weighted images remain the most accurate technique in the assessment of cerebral metastasis.

Sze et al(1995)[11] performed prospective and retrospective studies in seventy five patients. In forty nine patients, MRI and contrast enhanced CT were equivalent. In twenty six patients, however, results were discordant, with neither CT nor MRI being consistently superior. MRI demonstrated more metastases in nine of these patients.  Contrast enhanced CT, however, better depicted lesions in eight of these patients.

Chang et al(2002)[12]   compared diffusion weighted imaging and conventional atomic MRI to distinguish brain abscesses from cystic or necrotic brain tumour in eleven patients. They found out that post contrast T1-weighted images yielded a sensitivity of 60%, a specificity of 27%, a positive predictive value of 53%, and a negative predictive value of 33% in the diagnoses of brain tumour, while diffusion weighted imaging yielded a sensitivity of 93%, a specificity of 91%, a positive predictive value of 93%, and a negative predictive value of 91.

Ad Gouliomos, et al(2000)[13] studied one hundred and four patients with brain tumour, 13(12.5%) had histological evidence for calcification. Skull radiographs and CT scans of those cases revealed that in most instances calcification detected by CT was also present on skull radiograph. In cases with a high density lesion present on CT was below that which characterizes calcification. The study suggests a complementary role of the two modalities in investigating intracranial calcification.

  1. Moore et al(1993)[14] stated that MRI from clinical experience has proven to be superior to all other diagnostic imaging modalities, including CT in the detection of intracranial neoplasms. Although glioblastoma multiforme presents a challenge for all diagnostic imaging modalities including MRI. MRI is paramount to CT in detecting subtle abnormal water accumulation in brain tissue caused by tumour even before there is disruption of blood brain barrier.

Taghipour Zahir et al(2011)[15] studied two hundred and eight patients who hard brain neoplasm. One hundred and eighteen nine patients had definite diagnosis using CT scan, which 13(7.2%) were diagnosed benign and one hundred and fifty nine (92.4%) malignant. Sensitivity, specificity, positive predictive value and negative predictive value of CT scan in comparison with biopsy were 83%, 10%, 93%, 3% respectively. The accuracy of this method was 78%. Fifty four patients (24%) were evaluated by MRI. Sensitivity, specificity, positive predictive value and negative predictive value of MRI were 92%, 25%, 93%, 2% and 87% respectively. They concluded that positive results by MRI and CT are valuable and have diagnostic value, but negative reports need more evaluation and no roll out malignant tumour.

Miller et al(2009)[16]  studied fifty two patients with brain tumour and concluded that sensitivity and specificity of CT was 89% and 82% respectively while MRI has sensitivity and specificity of 92% and 99% respectively.

Morano p et al(2009) [16] used the information of fifty two patients that 48% CT scan reports were like biopsy ones. For MRI reports, also similar studies designed. Barlon reported that accuracy between its reports and biopsy was 76.1%.

Sarker A et al(2009) [16] used the information of fifty two patients and concluded that MRI has more accuracy than CT scan in the diagnosis of brain tumour.

Kim et al(2005)[17] demonstrated that a limited MRI scan could be considered for screening purposes. In one hundred and eight three patients, MRI detected 6% in 20% of the patients with brain metastases. They concluded that a CT scan is reasonable as first test but that MRI is required if the decision regarding treatment requires knowledge of the exact number of metastases.

Yuh et al(1994)[18] reported that high dose contrast (0.3mmol/kg gadolinium), as opposed to standard dose contrast (0.1mmol/kg gadolinium), is superior in brain lesion detection without any increase in serious toxicity. They concluded that strength of MRI magnet is important in the ability to detect brain metastases.

Hooper et al(1984)[19] found that CT scans did not reveal unsuspected brain metastases in patient without strong evidence of disseminated diseases such as neurologic signs and symptoms, bone pain or elevated serum calcium. The authors did not access the utility of CT scans in operable patients, and it is possible that their patient group had a more advanced stage of disease which would account for different conclusions. The authors concluded that the cost achieved by avoiding thoractomy was far larger than cost associated with CT scans.

Taddei et al(1999)[20] investigated a group of patient with brain metastases with clinical characteristics. In their group, made up of two hundred and eleven patients with age ranging from thirty three to seventy nine years, lung tumours (47%) and breast tumours (9%) were the most frequent cause of brain metastases.

The blue cross shield association medical advisory panel concluded that the magnetic resonance spectroscopy in the evaluation of suspected brain cancer did not meet the technology evaluation center criteria as a diagnostic tool.

Chao et al(2001)[21] studied forty seven patients with brain tumour treated with stereotactic radio surgery and followed with flurodeoxyglucose positron emission tomography. For all tumour types, the sensitivity of flurodeoxyglucose  positron emission tomography for diagnosing brain tumour was 75% and specificity was 8%. For brain metastases without MRI co registration, the sensitivity of flurodeoxyglucose positron emission tomography for diagnosing brain tumour was 65% and specificity was 80%. . For brain metastases with MRI co registration, the sensitivity of flurodeoxyglucose positron emission tomography for diagnosing brain tumour was 86% and specificity was 80%. MRI co registration appears to improve the sensitivity of flurodeoxyglucose positron emission tomography, making it useful modalities to distinguish between radiation necrosis and recurrent brain metastases.

Burger and co-workers(1983)[22] compared clinical history with CT and matched whole mount surgical or autopsy specimens in twenty patients with glioblastoma multiforme. They examined untreated, quiescent, and recurrent tumours. CT scans of untreated lesions revealed a necrotic center, with a rim of contrast enhancement surrounded by low-density area. The whole mount pathology showed necrotic areas corresponding to CT necrotic center, with a dense cellular rim of small anaplastic cells and significant vascular proliferation where CT contrast enhancement was seen.

Chamberlain and co-workers(1988)[23] reported the absence of CT contrast enhancement in 4% of patient with glioblastoma and in fifty four patients with highly anaplastic astrocytoma.

In summary, in high grade atrocytomas, the MRI area of enhancement and T2- weighted increased signal is greater than the CT area of enhancement and hypodensity.