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Despite its clinical application, computed tomography scan is not readily available in developing countries, like Nigeria. Some patients who require CT examination are either managed blindly, or do not present for it at the appropriate time. This study assesses the referral pattern, indications and results of CT referrals, as they are obtained in University of Nigeria Teaching hospital Ituku/Ozalla,Enugu.Retrospectively recorded data of all patients who presented for CT scan between May 2011- April 2012 at UNTH,Enugu were analysed. A total of 726 CT scans studied, were made up of 416 males (57.30%) and 310 females (42.70%). Majority of the patients were within the age range of 21-30 years representing 15.30% of all referrals. 29.01% (211) of all CT scans were referred from accident and emergency unit, followed by surgical out-patient department 11.98%.Analysis of the clinical indications showed trauma and RTA to be the commonest indication for brain CT referrals 21.81%, abdominal neoplasm/metastasis for abdominal pelvic CT scan 24.48%, respiratory difficulty for chest CT 25%, suspected cervical fracture for neck CT scan 38.09% and spondylosis for spine CT 61.54%. Analysis of the CT diagnosis showed cerebral atrophy to be the commonest result for brain CT referral 12.48%, hepatic disorder for abdominopelvic 12.58%, laryngeal cancer for neck CT 24%, PTB for chest CT scan 21.48% and spondylosis for spine CT 29.41%. Out of the 726 CT scan studied, 228 (31.40%) had normal findings while 498(68.60%) had abnormal findings. CT had made substantial impact on patient care, though the study showed a relatively poor referral rate to CT examination. The study recommends proper sensitization of health personnel on the wide clinical applications of CT and improved health care insurance scheme to ensure better access to modern diagnostic tools by patients.


Title page                                                                       i

Approval page                                                               ii

Certification                                                                   iii

Dedication                                                                     iv

Acknowledgment                                                           v

Abstract                                                                         vi

Tables of contents                                                                   vii

List of Tables                                                                 viii



  • Background 1
  • statement of problems 3
  • General objectives of the study 3
  • Specific objectives of the study                           3
  • Significance of the study 4
  • Scope of study 4
  • Review of related literatures 4



2:1   History of Computed tomography ( CT)               12

2.2     Basic principles of computed tomography                    12

2.3     Evaluation and generation of CT scanners                 13

2.4     Helical computed tomography                                       15

2.5     Multislice scanners                                               16

2.6     Other design of CT scanners                                17

2.7     CT System Components                                  18

2.8     Different CT Examinations                                  20




3.1     Research design                                                    27

3.2     Population                                                           27

3.2.1  Area of study                                                       27

3.2.2  Target population                                                      27

3.2.3   Subject selection criteria

3.3   Ethical approval                                                          28

3.4 Method of data of data collection28

3.4.1         Source of data                                                           28

3.4.2         Procedure for data collection                                    28

3.5        Data analysis                                                             28





CHAPTER FIVE:          46

5.1     Discussion                                                                      46

5.2     Summary of findings                                                       51

5.3     Recommendation                                                       52

5.4     Limitation of the study                                              53

5.5     Conclusion                                                                 53

5.6     Area of further study                                                53

References                                                                55





The advent of CT has revolutionized diagnostic radiology.  It is estimated that more than 62 million CT scans per year are currently obtained in the United States, including at least 4 million for children1.


Although computed tomography has been in use in the diagnosis of head trauma and some pathologies of other part of the body, it is only inthe last 15-20 years that it became widely used. In fact, since its invention in the 1970s, it has been shown to have wide application within all radiological sub specialties 2.CT has effectively replaced many other radiological procedures such as lymphangiography, catheter arterial and venous angiography of the brain and the spine 3.


New applications and clinical roles for CT has emerged in the last few years including CT angiography, pulmonary embolism detection, the diagnosis of abdominal pain and appendicitis and the investigation of renal colic.


The use of multi-detector technique and improved multi reconstructive algorithms has introduced newer opportunities in the use of CT for diagnosis of pathologies of the brain, spine, orbits, fracture and vascular system4.


Despite the vast clinical application, computed tomography is not readily available in developing countries like Nigeria and awareness of its clinical application based on anecdotal evidence is rather poor among general practice physicians and health care providers4.Enugu is a referral centre for the five south eastern states of Nigeria, but patients are also referred from other parts of Nigeria, especially the contiguous south-south and northern states5. Enugu as a state has over 723000 population6 with 17 L.G.A. Less than four (4) CT machines are in active use in Enugu as at the time of this research, with one owned by federal government and two by private establishment .This difference in acquisition could be attributed to high cost of machines, maintenance and poor awareness of its multifunctional attributes.


A previous study in Nigeria observed that the lack of CT scan facilities in a centre contributed a great deal to ahigh mortality rate of 19.8% in head trauma 7.In this environment, the prevalence of head injuries7,8,9,10., and other CT detectable pathologies had consistently risen over the decades. Unfortunately, many of these patients in many centres are still managed based on pre-CT era protocols, resulting in high mortality and morbidity. This is partially due to financial constraints, few CT scan centres which are not easily accessible to many of the referring doctors.Consequently,some patients who require imaging investigation are either blindly managed or do not present for CT scan at the appropriate time5.


There is also false impression that CT scan is expensiveand therefore, an avoidable financial burden to poor families.The pitiable transport facilities and unavailability of ambulance services make the transfer of ill patients to other hospitals particularly challenging. It is against this background that the researcher seeks to assess the pattern of computed tomography referrals in University of Nigeria Teaching hospital Ituku-Ozalla, Enugu state and hence the utilization of this veryimportant imaging modality.





  1. The clinical utility of CT has been associatedwith age and gender11.The distribution of this CT utility based on age and gender, to the best of the researcher’s knowledge has not been documented in our locality.
  2. Studies have also shown that, the most common clinical indications and diagnosis for CT examinations vary in different localities4, 5, 12. There is thus need to find out what is obtainable in our locality.
  3. Few documented research literatures on computed tomography referrals in our locality, is available.






The purpose of this study was to assess the referral patterns, indications and results of CT referrals in university of Nigeria teaching hospital Ituku/Ozalla, Enugu state.



  1. To determine the age and sex distribution of patients referred to CT examination.
  2. To determinethe distribution of body regions examinedof patients referred to CT examination.
  3. To determine the sources of referrals.
  4. To evaluate the indications and results of referrals for CT examinations.



  1. The significance of this research is aimed at prompting government and private individuals to see need to establish more CT diagnostic centres in Enugu state.
  2. This study will provide the needed baseline data that can be utilized by policy makers in the review of resources for the CT unit.
  • The result of this research work will be of immense help to radiology staffs in the efficient and effective management of CT unit.



The study was carried out for CT examinations done from May 2011- April 2012. Data collected includes demographic information (such as date of examination, age and sex of patients), body regions of the examination, indications for the examinations, radiological diagnosis and referring unit.
















In a cross-sectional studies by Hiltrud et al13,to access the medical practice in paediatric CT referrals among office based physicians  concluded that the most frequent indication  for a CT examination in children were trauma or a suspected cancer taking 57% of the CT scans.  42% of the referral was related to minor diagnoses such as sinusitis, ambiguous headache, indigestion/dyspepsia, renal examinations or other unspecified symptoms. The study also concluded that the frequency of referrals ofchildren to CT in Germany is moderate.  The study also revealed that children of age range 11-16 years has 49.5% of the referrals, 6-10 years having 37.1% and 0-5 years have 10.5%. Theyalsoshowed that 44% of all CT referral of children is by paediatrician, 26% by general practitioner, 34% by surgeons and 10% by other specialities.


In a study by Robert and Bree14   at Harborview medical centre in Seattle in which they reviewed CT and MRI examination medical records from 459  elective out- patientsby primary care physician concluded that 74% were considered appropriate and 26% were considered inappropriate. 58% of the appropriate studies were positive and affected subsequent management while 24% of inappropriate studies were positive affecting management.  The criteria  they used was based upon evidence-based appropriateness  criteria  developed by a radiology benefit management company (largely  based on ACR appropriateness criteria)  According to Bree, this is an important information for  policy makers as they struggle with physician and patient who are unhappily with restrictive  utilization management programmes  and payers and the public  who are looking for ways to decrease health  care cost and increase quality and safety of examination in an  era of higher awareness of effects of excess radiation


In a study by Erondu et al4 to determine the patterns of CT referrals and the utilization of CT by physicians in the south-south region of Nigeria observed that males represented 60.66%, while female represented 39.33% of the total sample size. He also noted that males constituted a greater population in all ages except for the ages ranging from 21-30 years.According to his findings, CT referrals for patients within 41-50 years had the highest occurrence 20.4%. Brain CT had the highest referral rate 63.8% and CT scan of the orbit had the lowest referral (1.11%) from clinician. The most frequency clinical indication according tothem, for brain CT is hematoma 17.4% and the least embolic stroke 1.03%. Abdominal pain (21.3%) was the most frequent reason for abdominal CT referral while the least from urolithiasis3.3%.Suspected cervical fracture was the most frequent reason for neck CT referral 58.86% and thoracic mass for chest CT 44%. He also noted that 40% of all referral showed abnormal findings for brain CT with 25% abnormal outcomes.  Also noted was a poor referral rate from physicians for CT examination within those periods.They also concluded that thoracic mass was the highest reason for chest CT, abdominal pain for abdominal CT in the south-south region of Nigeria.


Shrimpton andWall15 in their research at United Kingdom and otherEuropean countries showed that, there is a rapid increase of CT referrals in those countries.Their study indicated potential scope for improvement in the optimisation of protection for patients undergoing in CT examinations.


Shvartzmanet al12 also in their research work found to evaluate the indications and the results of referrals for brain CT by primary care physician found out that, contrary to their expectation, headache is the main clinical indication for brain CT in Israel. Out of the 3,230 CT scans performed, 38% were brain CT.Out of these, male represented 40%, female 57%.They noted also that the referral for brain CT increases with age, to peak at the oldest age group of over 80 with the exception of 60-69 year age group where a drop in the referral rate is noticed.Headache without neurological finding was noted as the main reason for referral in 38% of the patients, dizziness in 18% of the patients and trauma in 9% of the patients.In the analysed results of the CT, 65.8% were completely normal. Brain tumour was observed in 3.2% of the patients and cyst in 1.5% of patients. women were diagnosed with brain tumour at a significantly higher rate than men (P<0.05), the age groups 20-49 year old were diagnosed with an adverse outcome at a higher rate than other age groups (p<0.00005).Sinusitis was also found to be a common incidental findings


Simpson and Hartrick16 wrote in their publication that “CT scans are used extensively to investigate chest diseasebecause of their cross-sectional perspective and superior contrast resolution compared with chest radiographs’’. These advantages lead to a more accurate imaging assessment of thoracic diseases.They also noted in their audit of requests for CT examination of chest emanating from general practitioners, that 68% of the CT chest referral were inappropriate while 32% were considered appropriate. They concluded that many CT examination of the chest requested by general practioners could be avoided or replaced by simpler cheaper test with lower radiationexposure.


Ohaegbulam et al5noted that the ratio of male –female  referred for CT scans is 3.5: 1 and that 33.9% of the patients were in their 3rd -4th decade of life.  19.9% of patients had abnormal CT findings while 80.1% had abnormal CT findings. They concluded that the most common CT finding due to head injury were: cerebral contusions andoedema in 30.7%, subdural hematoma in 27% ,skull fracture in 23.4% and extra-dural hematoma  in 8.0%.


Kyu et al17 in their published articles noted that” geographical location of a hospital was found to be a significant predictor of CT use in Canada as urban location favoured CT use.



Shackford  et al18 also wrote that in developed countries, a CT san is even recommended for patients with mild head injury because one in five patients will have an acute lesion detectable by CT scanning.They concluded by asserting that CT scanning is essential in the management of patients with minor head injuries.



Brenner and Eric19observed that physicians often view CT studies in the same light, as other radiological procedures even though radiation dose are typically much higher with CT than with other radiological procedure. White and Linton20,21. supported this and reports that the largest increase in CT use,have been in the categories of paediatrics diagnosis and adult screening and these trends can be expected to continue for the next few years. The major growth area in CT use for children has been pre-surgical diagnosis of appendicitis, for which CT appears to be accurate and cost effective, though arguably no more so than ultrasonography in most case22. Estimates of the proportion of CT studies that are currently performed in children range between 6% and 11% 23, 24.


In a recent survey of radiologist and emergency room physicians 25, about 75% of the entire groups underestimated the radiation dose from a CT scan and 53% of radiologist and 91% of emergency room physicians did not believe that CT scan increased the lifetime risk of cancer. In the light of these findings by National cancer institute, the pamphlet Radiation risks and paediatric CT: A guide for health  care providers 1which was recently circulated among the medical community by the national cancer institute and the society  for paediatric Radiology is most welcome.


In a study by John and James 11 to evaluate trends in CT utilization at a university based, tertiary care, level 1 trauma centre hospital where CT performance was evaluated from 1998 through 2005. From their data set, the age and sex dependency of CT utilization were evaluated for out-patient, in patient and emergency room patient, they found the following results. Out-patient utilization rates averaged over the age groups of 21-30 years old, 41-50 years and 61-70 years were 20, 59 and 87 CT scans per 1000 out patient visits respectively. In -patient use for the same age group were 88, 148 and 162 CT scans per 1000 in-patient days. CT utilization rates for emergency room (ER) patients were 705, 687 and 394 CT scans per 1000 ER patient visits for the same 3 age groups. For out- patient population, females have a large number of CT scans in the midlife (40-60 years) timeframe.  For in-patients, male have higher CT scans from late adolescence through mid-life in this category. For emergency room-patients male patient CT scans substantially out number female patient CT scans until approximately age 60. A large spike in CT scan utilization in 17-25 years age groups is quite pronounced for male patients. These trends reflect incidence statistics for motor vehicle accidents and other forms of traumaticinjury in that demographic26.

BEIR 27 risk data suggest that females are more sensitive to radiation induced cancer than males with the incidence of radiation induced cancer being 1.8 times higher of age 10, 1.7 times higher at age 20 and 1.5 times higher of age 30. Radiation risk for male steadily decreases with age, from 14.4 fatal cancers per 1000 exposed people of 100 mGy exposure at age 10 to 4.92 cancers of age 60.For female, the radiation incidence is 26.0 per 1000 of exposed individual at age  60. The decline in radiation induced cancer risk is steepest for males and female from birth to about age 40 and is less steep until gradually tapering to zero at about age 86.The age and sex dependences of radiation risk suggest that from the perspective of avoiding cancer induction by CT, that CT be used sparingly for younger patients.



Thomas R et al28 also in a prospective study carried out in Tayside and North East fife Scotland to determine, whether primary care access to brain CT referral  for chronic headache  reduces referral to secondary care, concluded that imaging  reduced referrals  to secondary care by 86% in the follow-up period.


Asaleye et al9in their study at Ile-Ife, Nigeria to determine the pattern of computerized tomographic findings in moderate and severe head injuries found out that 87% of patients had abnormal CT findings. 70% were male and 30 % were female. The age group mostly affected were those in second and third decades of life. 87% of the patients had abnormal CT findings while 13% showed grossly normal finding. Intracranial haemorrhage was demonstrated in a large number these patients.

Kristin B lysdahl and Bjourn29 noted in their study that the most important causes for increased use of radiological investigation volume are expanded medical possibilities,supply and demand of services. The later is also regarded as major causesof unnecessary radiological investigation.

Jo H, et all 30 in their study to assess the referral patterns for   CT examination found out that majority of requests were from emergency (ED) or urology department 49% and 37% respectively. They noted also that positive rate for urolithiasis was 67% and that female are more likely to have a negative study than male patients (35 versus 20%, p <0.0001). They noted also that patients referred by specialities other than emergency andurology was more likely to be female.

Shlomit Goldberg-stein et al31 in their research study concluded that, chest CT use increased on average 75%/y/100 deliveries in pregnancy versus 19%/y increase in all patients p =0.2700 and that abdominopelvic CT utilization increase was on average 22%/y/100 deliveries in pregnant patients versus 13%/y/ in all patients p = 0.1865). They also noted that the most common indications for chest CT during pregnancy was suspected pulmonary embolism 85% and for abdominopelvic CT, suspected appendicitis 58%.

Tom AP et al 32 found out that there has been an average increase of 11% per annum in the number of examinations performed in body CT unit and that the increasing number of body CT examination is more on elderly patients.


Olsson S33 also noted that the regional variations in access, use and utilisation of CT and MRI were surprisingly large and reimbursement policies by the country councils for CT and MRI examinations varied which agave different incentives for patient referrals

Erdogen D, et al34 in their study also identified right upper abdominal pain (59%) as the most common reason for referral of patient to abdominal CT.


Mebrahtu et al35 in their study , to assess the findings in acute head injury observed that the overall male to female ratio was 3:1 and that the most common CT findings were intra cerebral hematoma 20%, cerebral contusion or laceration 16.4%, skull fracture 6%, and scalp swelling 2.7%.




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