We Rank the Best on Research Projects

EVALUATION OF THE DIAGNOSTIC YIELDOF MRI IN THE DIAGNOSIS OF BRAIN TUMOUR (A CASE STUDY OF NATIONAL HOSPITAL, ABUJA)

Dept: MEDICAL RADIOGRAPHY AND RADIOLOGICAL SCIENCE File: Word(doc) Chapters: 1-5 Views:

Abstract

The aim of this research is to evaluate the diagnostic yield of MRI in the diagnosis of Brain tumour, at National Hospital, Garki Abuja.It is a retrospective study, which evaluated the diagnostic yield of MRI in the diagnosis of Brain tumour, the sensitivity, Specificity, and accuracy of the Imaging Procedure in the Management of Brain tumour. The study also showed the male and female distributions of brain tumour cases in the period of February 2009 and March, 2012.A total number of 116 records (52 males and 64 females) that met the inclusion criteria was retrieved and studied. The result showed that MRI has a high estimated diagnostic yield with a value of 103 (88.79%) of the total population. The population of females (n=64; 55.7%) with brain tumour is greater than male, (n=52; 44.83%) patients. It was discovered that there is a high incidence of brain tumour in the locality. It was also discovered that MRI is a very useful tool in detection and management of brain tumour and as su

1.1 BACKGROUND OF THE STUDY

Brain tumor is an intracranial neoplasm or an abnormal growth of cells within the brain

1

. It is one of the most devastating forms of human cancers. They cause considerable concern due to their relatively high morbidity, mortality and enormous cost of care especially in the developing world where the financial burden is carried by the poor patient and his or her relations. Brain tumours develop as a consequence of cellular genetic alterations that permit them to evade normal regulatory mechanism and destruction by the immune system. These alterations may have an inherited or acquired (chemical, physical or biological) cause. Over all, only a small proportion of brain tumours can be attributed to the effect of inherit predisposition

2

.The various implicated and suspected environmental factors include: ionizing  radiation, non-ionizing radiation, N – nitroso compounds, viral infections (JC virus, cytomegalovirus, human immunodeficiency virus, sv-40, varicella zoster, chicken pox) and head injury

2,3,4,5

Different imaging modalities have been used in the diagnosis of patients with brain tumour. Skull radiography, computed tomography and magnetic Resonance imaging are all important tools in the diagnosis of brain tumour in patients. However, skull radiography and CT are less used due to the risks associated with these imaging modalities. Therefore, MRI is currently the imaging modality of choice in the diagnosis of patients with brain tumours.

6

For the fact that the use of MRI in brain imaging is rapidly increasing because of its relevance in both research and clinical medicine, the scanner hardware and MRI sequences are also improving. Performing MRI at higher resolution and field strength and  with more sensitive sequences have led to the detection of subtle or small brain abnormalities that may not be detected with other related modalities like computed tomography (CT)

7

. MRI studies of the brain is considered a better imaging technique than CT for two reasons: Firstly, MRI has a much higher contrast resolution when compared with CT for clear demonstration of normal anatomical structures and associated pathologies of the brain. Unlike CT angiography, intravenous contrast injection is not required for MR angiography. This is advantageous in patients with impaired renal function, contrast allergy or no intravenous access. Secondly, MRI does not involve radiation exposure unlike CT where x-ray source is used to produce image by exposing the patient to about 2msv of radiation which is twenty times that of conventional chest x-ray. It implies therefore, that one non-contrast CT brain study is equivalent to the amount of background radiation one experiences in about 8 months

8

. However, the use of MRI is contraindicated in patients with pacemakers and other metallic devices.

Any brain tumour is inherently serious and life-threatening because of its invasive and infiltrative character in the limited space of the intracranial cavity. So, there is need to evaluate the diagnostic yield of MRI in the diagnosis of brain tumour. This necessitates this study which will evaluate the diagnostic yield of MRI in the diagnosis of brain tumor in the institution under study.

 

1.2 STATEMENT OF PROBLEM

1. Brain tumour is one of the leading causes of death among adult and middle aged group and it poses serious emotional and economic loss

   9

   .The diagnostic yield of MRI in the diagnosis of brain tumour has not been evaluated in the location under study.
2. Analysis of patterns of MRI findings in patients with brain tumour has not been done in the locality under study to the best of the researcher’s knowledge.

 

1.3 OBJECTIVE OF THE STUDY

1. To determine the prevalence of brain tumour in the health institution understudy.
2. To document the common MRI findings in patients with brain tumours.
3. To determine the diagnostic yields of MRI in the diagnosis of brain tumours.
4. To document the mostly affected age range and gender
5. To determine the specificity, sensitivity and accuracy of MRI in detection of brain tumours

 

1.4 SIGNIFICANCE OF STUDY

1. The study will help us toknow the prevalent MRI findings in the cases of brain tumours as it will enhance proper management of the patients.
2. The study will help us to have a document on MRI findings in brain tumours in the locality for further reference and research purpose.
3. The study will enable us to know the pertinent role that MRI plays in the diagnosis of brain tumours.
4. The study will help educate the stakeholders on the common MRI findings in brain tumours and as such will help reduce mortality rates.

 

1.5 SCOPE OF STUDY

This study surveys brain MRI done in brain tumour cases at National Hospital, Abuja (NHA).It covers all the brain tumour cases from February 2009 to March 2012, a period of 38months.

 

 

 

 

1.6     LITERATURE REVIEW

Magnetic Resonance imaging (MRI) continues to have a large impact on the diagnosis and management of a number of disorders of the brain

10

. The importance of MRI lies in the optimum soft tissue contrast and the large number of specific biological and physiological parameters that can be measured.

Some related literatures were reviewed to know what other researchers have done and their various findings.

Lipsitz,et al

11

in their research work, found that glioblastoma multiforme(GBM) is the most common and most aggressive malignant primary brain tumour in humans, involving glial cells and accounting for 52% of all functional tissue brain tumour cases and 20% of all intracranial tumours. Despite being the most prevalent form of primary brain tumour, GBMs occur in only 2-3 cases per 100,000 people in Europe and North America. According to the WHO classification of the tumours of the central nervous system, the standard name for this brain tumour is glioblastoma.Radhakrishman et al

12

 in their research on the incidence ofprimary brain tumour, discovered that primary brain tumour represent only 2% of all cancers, with 35,000 new cases diagnosed each year in the united state. Meningioma occur at the rate of 7.8 per 100,000 per year, but only 25% are believed to be symptomatic, with others being found incidentally.The male to female ratio is 1:1.8, and the incidence increases with age, peaking at age 85 years.According to cancer brain tumour registry of the united states (CBTRUS)

11

, the incidence of oligodendrogliomas, including anaplastic oligodendrogliomas, is approximately 0.3 per 100, 000 persons and these tumours account for 4% to 15% of intracranial gliomas.According to O’neil and  widigicks

13

, primary brain tumour accounts for 3% of all neoplasm but is the most common solid tumour in children, accounting for 35% of all paediatrics malignancies. They also concluded that 2120 new brain tumour occur in Canada yearly and 50% of the brain tumour occur in adult between 40 – 60 years.In a study by cairncross et al

14 

on MRI characterization of primary malignant brain tumors (PMBTs). They posited that PMBTs are typically hypo-intense on T1-weighted images and hyper-intense on T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. They also found that the higher-grade lesions (WHO III and IV) are more likely to demonstrate enhancement (anaplastic oligodendrogliomas,anaplasticastrocytomas,glioblastoma multiforme),although ring enhancement is less common in anaplastic oligodendrogliomas and usually is associated with a worse prognosis. However, glioblastoma multiforme often has ring enhancement around a central area of necrosis whereas tumour associated cysts are more common with astrocytomas.Goldman et al

15

 in their research observed that in children under the age of 2 years, about 70% of the brain tumour are medulloblastoma, ependymoma and low grade glioma whereas teratoma and a typical teratoid rhabdoid tumour areless commonly seen in children.They also noted that germ cells tumours including teratoma make up just 3% of paediatric primary brain tumours but its incidence varies significantly in different part of the world.Staneszek 

16

 in his study of meningiomas and small brain aneurysms among people of age 45 year or above,found out that the growth of meningiomas is typically slow and most meningiomas remain asymptomatic throughout life which explains why 50% of all meningiomas found at autopsy in persons over 60 years of age is 3% and the majority of lesions are less than 1cm in diameter.In the Rotterdam study

17

 aimed at investigating the causes and consequences of age-related brain changes among persons of 55 years of age or above who were living in suburbs of Rotterdam, in Netherland. All participants (7983) without contraindications to MRI were invited to undergo MRI examination. All scans were obtained with a 1.5 Tesla scanner with an eight channel lead coil.Two trained technicians performed all examinations in a standardized way, the MRI protocol was identical for all participants and included four high resolution axial sequences, three dimensional T1-weighted sequence of the slice thickness of 1.6mm, a two dimensional Proton-density weighted sequences with slice thickness of 0.8mm and a two dimensional FLAIR sequences with slice thickness of 2.5mm. The mean age of the study population is 63.3 years (range 45.7-98.7) and 1049 of the subjects (52.4%) were, women. Asymptomatic brain infarcts were present in 145 persons (7.2%), aneurysm (1.8%) were the most frequent. Benign tumors were also frequent (1.6%) with meningioma being recorded most often (0.4%). The meningioma ranged from 5-60mm in diameter and their prevalence was 1.1% in women and 0.7% in men. Pituitary macroadenoma was present in six persons (0.3%), vestibular schwannomas has 0.2% prevalence. The median volume of white matter lesions increased with increased age. In conclusion, asymptomatic brain infarcts, white matter lesions and meningiomas increased with age whereas aneurysms showed no age related increase.Levin 

18

 studied fifty patients with mild to moderate closed head injury. (CHI) who underwent a CT scan, MRI and neurobehavioural testing. At baseline 40 patients has intracranial hyper intensities detected by MRI which predominated in the frontal and temporal region whereas 10 patients have lesions detected by CT.Their result corroborate and extend previous findings indicating that more intracranial lesions can be detected by MRI in most patients hospitalized after mild to moderate head injury.Kumar

19

 performed a study to determine the severity of tissue damage after severe head injury as assessed with magnetization transfer (MT) MR imaging and the relationship of this damage with seizure intractability. He observed disturbing abnormalities and this suggests that T1-weighted MT imaging may be of value in predicting the intractability of the seizure in delayed post-traumatic epilepsy.In a study by vernooji et al 

20

 to investigate incidental brain findings with MRI in 1000 asymptomatic subject that were 55 years old and above using high resolution 1.5 tesla MR scanner; the disorders they discovered include subclinical vascular pathologic changes, which were common in the general population. The most frequent findings were brain infarcts,followed by cerebral aneurysms and benign primary tumours. They also found that the prevalence of asymptomatic brain infarcts andmeningiomas increased with age, as did the volume of white-matter lesions, whereas aneurysms showed no age related increase in prevalence.Katzman

21

  in his work, investigated the incidental finding of brain MRI in 1000 asymptomatic  volunteers with 1.0 tesla MR scanner and obtained the images with T1-weighted and T2-weighted imaging sequences. Eight-two percent of the MRI result were normal.Out of the 18% demonstrating incidental abnormal findings, 15.1% required no referral, 1.8%, routine referral, 1.1% urgent referral and 0% immediate referral. In subject grouped for urgent referral, 2 confirmed primary brain tumour (and a possible but unconfirmed third) was found, demonstrating prevalence of at least 0.2%. This shows MRI sensitivity in detecting abnormalities in individual presumed healthy.Gatopoulou

22

 in his work, found a meningioma on T1-weighted axial MR image of a patient with crohn’s disease despite the absence of neurological symptoms and electromyography abnormalities.Koretsky

23

 comparatively investigated sensitivity of functional MRI and conventional MRI in the detection of brain lesions in injury in a group of patients who had stabilized after recent history of head trauma using T1-weighted sequence in a 1.5 tesla MR scanner for normal standard MRI scan and T2-weighted sequence for fMRI. The result of his study showed that detailed characterization of hamodynamic, tissue integrity and neuronal activity are the advantage of functional MRI technique. The impact should be in better defining brain regions affected by injury and monitoring recovery due to treatment and changes in brain function due to plasticity. His finding further highlights the sensitivity of MRI in detection of brain lesions.Atlas et al

24

 in their research on functional MR imaging of regional brain activity in patients with intra-cerebralgliomas; the examination was performed among seven patients proven by histological analysis using a non-invasive blood oxygen level-dependent technique based on the documented discrepancy between regional increase in blood flow and oxygen use in response to regional brain activation. Both fMRI and conventional MRI were combined during motor or language task experiment to investigate the potential usefulness of mapping regional brain activity as a part of treatment planning in patients with intra-cerebralgliomas, in whom preservation of areas of functioning brain tissue is critical.

Statistical fMRI maps were generated and directly mapped unto conventional MRI scans obtained at the same session of the five patients cooperative enough to remain motionless for the study and perform the task, the location of activation in the primary sensorimotor cortex on the side of the tumor was clearly displaced compared with that in the normal contra lateral hemisphere in four patients. Four of the five tumors in these patients showed fMRI activation within the periphery of (or immediately adjacent to) areas of presumed tumor based on spin echo MRI. They concluded that blood oxygen level-dependent fMRI can localize areas of cortical function in patients undergoing treatment planning for gliomas so that therapy can be directed away from region of residual function.

Researchers were also carried out to determine the influence of radiotherapy quality on survival of patients in high-risk medulloblatoma.

Paulino et al

25

 presented 25 patients treated in two radiotherapy department in 20 years period. Treatment schedule included radiotherapy (Craniospinal in 68%, whole brain followed by a boost in 8%, and primary site alone in 24%). Median dose to whole brain and spine was 36Gy, and primary site 54Gy. 64% of patients recieved chemotherapy, the most common type was in “8 in 1” regimen.

The 5 year and 10 year progression free survival rate was 36% and 27% respectively, 47% and 47% for those recieving craniospinal radiotherapy, and 12.5% and 0% for those recieving less extended radiotherapy fields. On multivariante analysis, only dissemination in neuraxis and radiotherapy volume were statistically significant. The primary site control was 62% and failure at non-treated neuraxis site was a common cause of progression in patients receiving whole brain or primary site radiotherapy. Leptomeningeal dissemination as a site of relapse was observed in 76% patients and the authors concluded that the result of the study do not support lowering the craniospinal dose of the supratentorial PNET

Patil

26

 listed types of inherited disease associated with brain tumours. In his findings, the under listed diseases were recorded;

• Multiple endocrine neoplasm type 1 (pituitary adenoma)
• Neurofibromatosis ( malignant retinal glioma)
• Tuberous sclerosis ( primary brain tumour).etc

In a study by Moller-Hartmann et al

27

, on the diagnostic performance of MR Imaging and Proton MR Spectroscopy versus MR Imaging alone in the characterization of braintumours, among 176 patients. The final diagnosis in most patients was established by histology within 10 days of single voxel 

1

H-MR Spectroscopy. One pair of radiologists interpreted only the MR images; a second pair examined the MR imaging and MR Spectra based on a qualitative interpretation of metabolite peaks. All Radiologists were unaware of the final diagnosis. The type and grade of lesion were correctly identified in 97 of 176(55%) Cases based on MR Imaging alone. The remaining diagnoses were incorrect (15%) or indeterminate (30%). The addition of 

1

H-MR Spectroscopy information statistically significantly increased the proportion of correctly diagnosed cases to 71% (124/176). There were no cases where a correct diagnosis on MR imaging was mistakenly discarded due to the 

1

H-MR Spectroscopy findings.Another study by Ando et al

28

 compared contrast-enhanced MR imaging (CE-MR imaging) to CE-MR imaging and 

1

H-MR Spectroscopy in 20 patients with suspected residual or recurrent tumour after therapy. The method of final diagnosis was inconsistent between patients, relying on either pathologic or clinical findings. Fourteen patients had a final diagnosis of residual or recurrent tumor, and 6 had treatment-related changes. The authors retrospectively selected a choline/Creatine ratio of greater than 1.5 to be indicative of tumour. Based on this threshold, the addition of 

1

H-MR Spectroscopy information to CE-MR imaging findings marginally increased from 12 of 14 (86%) to 14 of 14 (100%) without altering specificity (4 of 6; 67%).Two studies from the same research group evaluated the differentiation of necessities from high grade astrocytoma by using long

29

 and short

30

 echo time 

1

H-MR Spectroscopy. Both studies retrospectively assembled a cohort of patients from multiple hospitals. The MR hardware varied between hospitals, but Spectroscopy was performed using standardized protocols. Both studies used automated spectral analysis of diagnostic classification. At long and short echo times, the area under the ROC curve (AUC) for differentiating glioblastomas from metastases was relatively poor (AUC=64% and 59%) respectively. This is statistically significantly better than chance alone; however, it is not high enough to suggest that 

1

H-MR Spectroscopy can be relied upon to differentiate metastases from glioblastomas.Opstad et al

31

prospectively recruited 44 patients with pathologically proved glioblastomas

32

or metastases

29

, 7 patients were later excluded due to poor quality spectra. The authors focused on the lipid-peak-area ratio derived from short echo time, single voxel 

1

H-MR Spectroscopy. They defined this as the ratio of L1 (the combined alanine, lactate; &?1.4 macromolecule, and ?1.3 lipid peak) to L2, the combined ?0.9 lipid and ?0.87 macromolecule peaks).Using this ratio, they reported an AUC of 84% with both sensitivity and specificity equal to 80% at a threshold value membrane structure of infiltrative versus migratory tumor cells or to lipid metabolism.McKnight et al

33

, Prospectively recruited 44 patients with suspected glioma before image guided re-section or stereostactic biopsy of the tumour. Data from the pre-operative multivoxel 

1

H-MR Spectroscopy study was used to select 4 potential targets for biopsy in each patient. In practice, the authors were unable to obtain biopsy samples at each target, and their analysis was based on 100 samples, of which only 7 were classified as non-tumour. The authors based diagnosis on the choline-N-acetylaspartate index (CNI), where CNI is the number of standard deviations between the choline (cho) to NAA ratio within a given voxel and thatof the control voxels. At a threshold CNI of greater than 2.5, the authors reported 90% (95% C.I, 84-96%) Sensitivity and 86% (95%C.I, 56%-100%) specificity for predicting the presence of tumor in the biopsy sample. The overall AUC for CNI was 94% (95% CI, 87%-99%). Up to half of the T2-hyper intense lesion outside of the gadolinium-enhanced lesion contained CNI greater than 2.5. This suggests that 

1

H-MR Spectroscopy might have a considerable therapeutic impact on surgical and radiation target volumes.Murphy et al

34

 performed 

1

H-MR Spectroscopy in 100 consecutive patients with suspected brain tumors. The authors highlighted 2 cases incorrectly classified as glioblastoma based on conventional imaging that were correctly down-graded to grade 2/3 astrocytomas based on 

1

H-MR Spectroscopy. In a further 4 cases, the differential diagnosis of arachnoid cyst, infection, stroke, or meningioma were correctly excluded on the basis of 

1

H-MR Spectroscopy.The authors concluded that in 6 of 100(6%) cases,

1

H-MR Spectroscopy could have made a significant contribution to the pre-operative diagnosis. It was unclear whether 

1

H-MR Spectroscopy provided confirmatory or contradictory information in the remaining patients.The study by Hallet al

35

 looked at the impact of 

1

H-MR Spectroscopy on the diagnostic yield of biopsy. 

1

H-MR Spectroscopy was used in 42 patients and all 42 biopsies yielded diagnostic tissue; however, the lack of a control group who did not get 

1

H-MR Spectroscopy-guided biopsy limits the value of these results. No firm conclusions can be drawn about the incremental benefit of 

1

H-MR Spectroscopy in guiding biopsy.Pirzkall et al

36

 recruited 20 patients with grade II gliomas who underwent both MR Imaging and 3D multivoxel 

1

H-MR Spectroscopy before surgery. The target volume based on MR imaging was compared with 

1

H-MR Spectroscopy target volume based on areas of the tumor with a Cho/NAA index greater than 2 (CNI 2). Due to technical limitations, Spectra were only available for an average of 68% of the tumor volume. In the tumor regions that were assessed by both MR imaging and 

1

H-MR Spectroscopy, 96% of the 

1

H-MR Spectroscopy-defined tumor volume was contained within the MR imaging-defined volume. Despite this, in 45% of patients, some portion of the 

1

H-MR Spectroscopy-defined tumor margin extended beyound the MRimaging-defined volume.The authors suggested that MR spectra can be used in conjunction with MR images to fine tune the clinical target volume. The same researchers also published a study of multivoxel 

1

H-MR Spectroscopy on 30 high-grade gliomas after but before adjuvant radiation therapy

33

. MR imaging target volumes were compared with the 

1

H-MR Spectroscopy-derived CNI2 volume. By adding the area of metabolic tumour cell infiltration, defined by the CNI2 to the MR imaging target volume, the authors found a 14% increase in the clinical target volume for radiation therapy. Of 10 patients who had had ostensibly total tumour re-section, all had areas of residual elevated CNI and 8 had a new onset of contrast enhancement during follow-up. In 4 of these 8 cases, the area of contrast enhancement was located within the area of elevated CNI2. There was also a direct relationship between a large volume of residual CNI2 and a shorter time to occurrence of new contrast enhancement, though this was of borderline statistical significance.

In the course of the reviewing literature, the researcher found that no study has been made to document the analysis of common MRI finding in patients with brain tumours in the area under study, hence, there is need to carry out this research as first of its kind in the area under study.