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Table of Contents
ORIGINAL ARTICLE
Year : 2019  |  Volume : 12  |  Issue : 4  |  Page : 204-207

Radiographic assessment of cardiothoracic ratio in apparently healthy adults in Maiduguri


1 Department of Radiology, Federal Neuro-Psychiatric Hospital, Maiduguri, Borno, Nigeria
2 Department of Radiography, College of Health Sciences, Usmanu Danfodio University, Sokoto, Sokoto State, Nigeria, India

Date of Submission21-Mar-2019
Date of Acceptance04-Jun-2019
Date of Web Publication11-Nov-2019

Correspondence Address:
Alhaji Modu Ali
Department of Radiology, Federal Neuro-psychiatric Hospital, P.M.B 1322, Maiduguri, Borno
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/HMJ.HMJ_25_19

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  Abstract 


Background: Cardiothoracic ratio (CTR) is an easy and cheap diagnostic tool in the estimation of the cardiac sizes which is used for the screening and diagnosis of cardiac diseases. Objectives: The study objectives were to assess the normal cardiac size in apparently healthy adults and establish reference ranges in our population for comparison when investigating cardiac diseases. Materials and Methods: Radiographic evaluations of the cardiac size were performed from March 2017 to February 2018 in 172 apparently healthy individuals who were referred to the Radiology Department, Federal Neuro-Psychiatric Hospital, Maiduguri, in Nigeria, for medical examinations. The individuals were divided into the following five age groups: 18–27, 28–37, 38–47, 48–57 and 58 years and above, in order to determine the influence of age on cardiac size. Results: The mean CTR for males and females was 45.10% and 45.71%, respectively, and was statistically insignificant (0.362). The mean CTR of the general population was 45.6%, and the mean CTR value increased with age until the fourth decade when it reduces with age. Conclusion: The result of this study has established the CTR of the Nigerian population in Maiduguri. The CTR gradually increased with age until the fourth decade when it reduces with age. Therefore, establishing normal ranges of CTR is necessary for comparison in a condition where a possible cardiac disease is being examined.

Keywords: Adult, cardiac, cardiothoracic ratio, healthy, radiograph


How to cite this article:
Ali AM, Gangrang AS, Abubakar A, Abubakar U. Radiographic assessment of cardiothoracic ratio in apparently healthy adults in Maiduguri. Hamdan Med J 2019;12:204-7

How to cite this URL:
Ali AM, Gangrang AS, Abubakar A, Abubakar U. Radiographic assessment of cardiothoracic ratio in apparently healthy adults in Maiduguri. Hamdan Med J [serial online] 2019 [cited 2019 Dec 13];12:204-7. Available from: http://www.hamdanjournal.org/text.asp?2019/12/4/204/270674




  Introduction Top


Cardiothoracic ratio (CTR) is one of the accepted methods of evaluating the cardiac size, and it provides prognostic information in acquired cardiac diseases.[1] Cardiac size is estimated from the postero–anterior (PA) radiograph of the chest by calculating the CTR. This is the ratio between the maximum transverse cardiac diameters (MTCDs) and the maximum internal thoracic width (MITW) above the costophrenic angles measured from the inner edges of the ribs.[2],[3] The value of 50% is generally considered to indicate the upper limit of normal in an adult. However, this value varies because of many cardiac and extracardiac factors influencing these measurements. These include type of projection, thoracic alterations (scoliosis and pectus excavatum), lung size, breathing phase, cardiac cycle phase and the cardiac rate at the time of examination.[4]

Assessment of the cardiac size including the size of each of the four cardiac chambers is crucial as it helps clinicians in ascertaining the causes of cardiac enlargement. Although the size of the cardiac chamber can be determined by chest radiography, the diagnosis can be made more accurately by other imaging modalities such as cardiac echocardiography, magnetic resonance imaging (MRI) and computed tomography (CT).[5]

Echocardiography provides a better assessment of the cardiac chamber size and function than the plain chest radiography. Studies have shown that echocardiography is more sensitive and specific in determining cardiac chamber size; however, its cost and availability make it difficult and expensive to obtain an echocardiogram on every patient.[5] Advanced imaging modalities such as CT and MRI also provide an accurate assessment of the cardiac chamber function and size because of their multiplanar capabilities.

Conventional radiography is readily available, is cheap, is less complex and allows easy assessment of the cardiac size and its changes over time.[6]

The objective of this study was to investigate the normal cardiac size by radiography in adults who have known cardiac disease and to determine the influence of some demographic variables on cardiac size to establish the normal CTR values so that comparisons can be made in conditions where cardiac disease comes into question.


  Materials and Methods Top


The study was carried out at Federal Neuro Psychiatric Hospital Maiduguri from March 1, 2017 to February 30, 2018 and included 183 PA chest radiographs. Patients of both genders and aged 18-60 years sent from the community clinic were included. In addition, the individual's brief medical history and blood pressures were taken by the researcher just prior to the radiographic examination. Individuals aged below 18 years and above 60 years, those with kyphosis, those with a present or past history of cardiovascular disease or those with systolic blood pressure <110 or >140 mmHg and diastolic blood pressure <60 or >84 mmHg and individuals whose radiograph showed ribcage abnormality, obvious cardiac/respiratory abnormality or radiograph with a significant rotation were excluded from the study. The sample population was drawn from the individuals referred from the community clinic for chest X-ray examination (medical examination for employment, school admission, visa application, etc.). A total of 172 apparently healthy individuals (76 males and 96 females) were enrolled in the study after the screening.

Radiographic examination was performed with an XR 6000 machine (GE Healthcare, Beijing, China) and Direct View Vita computed radiography reader system software/V3.2 Lite (Carestream Healthcare Inc. Rochester, USA). The participants were given some instructions such as removal of radio-opaque objects around the chest region which may affect the diagnostic quality of the image as well as breathing technique rehearsal (deep and arrested inspiration) prior to the positioning and the X-ray exposure while wearing an examination gown. In each case, a well-collimated horizontal X-ray beam was centred at the level of the 8th thoracic vertebrae (the spinous process of T7) while exposures were made at normal, quite arrested inspiration. All radiographs were acquired with the participant in erect PA position at a film focus distance of 150 cm [Figure 1].
Figure 1: Radiographic positioning of the chest examination (Source, Federal Neuro-Psychiatric Hospital, Maiduguri)

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The radiographic measurement included the MTCD and the MITW. The MTCD was obtained by measuring the horizontal distance between the most rightwards and leftwards borders of the heart as seen in the chest radiograph, whereas the MITW was measured as the horizontal distance inside the rib at the widest point above the costophrenic angles as seen on the PA chest radiograph [Figure 2]. These measurements were used to calculate CTR as follows:
Figure 2: An adult postero–anterior chest radiograph demonstrating how to measure maximum transverse cardiac diameter, maximum internal thoracic width and cardiothoracic ratio (Source, Federal Neuro-Psychiatric Hospital, Maiduguri)

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In order to establish the standard normal reference values of CTR, the participants were stratified into the following five age groups: 18–27 years (n = 29), 28–37 years (n = 62), 38–47 years (n = 50), 48–57 years (n = 16) and 58 years and above (n = 15).

Data analysis was carried out using the Statistical Package for the Social Sciences (SPSS) SPSS Version 22 IBM General electric (GE), X-R6000, Beijing, China. Both descriptive and inferential statistics were employed. The descriptive statistics used were expressed as mean ± standard deviation values. To compare the mean MITCD, MITW and CTR of the male and female participants, Student's t-test was used, whereas the Pearson's correlation coefficient was used to test the level of significance of the linear association between variables. P < 0.05 was considered statistically significant.


  Results Top


In this study, a total of 172 radiographs of apparently healthy individuals comprising 76 (44.18%) males and 96 (55.81%) females were evaluated. The mean age of the general population was 36.59 ± 8.54 years, with a range of 18–60 years.

[Table 1] summarises the mean values of MTCD, MITW and CTR of the study population. The mean values of MTCD, MITW and CTR for the population were 28.48 cm, 13.03 cm and 45.6%, respectively.
Table 1: Mean of the maximum internal thoracic width, the maximum transverse cardiac diameter and cardiothoracic ratio of the study population

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The mean CTR in males and females in our population was 45.10% and 45.71%, respectively, with a statistically insignificant correlation (0.363), although slightly higher in females. However, the mean MTCD and MITW values in males were significantly higher than that in females (0.000), as shown in [Table 2]. The mean CTR value of each age group at a 95% confidence interval was obtained, as shown in [Table 3]. The mean CTR value for the general population significantly correlated well with the participants' ages (P = 0.048). However, there was no statistically significant correlation between age and both the MITW (0.100) and MTCD (0.742). The CTR increases with age up to the fourth decade and then starts to decrease.
Table 2: Comparison of the mean values of the cardiothoracic ratio, the maximum internal thoracic width and the maximum transverse cardiac diameter with gender

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Table 3: Correlation between age and the mean maximum thoracic width, maximum transverse cardiac diameter and cardiothoracic ratio

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  Discussion Top


CTR is a simple measurement and calculation that can be carried out in a short period of time and needs only one X-ray exposure to produce the radiograph. Its relevance and importance are apparent not only in assessing the patient at the first contact but also becomes increasingly important during the subsequent assessment of the patient during follow-up visits. The status of the patient with respect to the heart can be assessed, and timely intervention can be made to save the patient's life.[7]

This study of 172 apparently healthy individuals of cardiac disease showed that a normal CTR is 45.6% in Maiduguri population. The mean CTR value in our study is similar to that reported for apparently healthy Ghanaians (45.2% and 46.0%, respectively), showing an absence of disparity between CTR and ethnicity.[6],[8] The finding that there was no significant difference in CTR between males and females in our study is consistent with other studies.[6],[9] However, in our study, the CTR value in females (45.71%) was slightly higher than that of males (45.51%), which is in agreement with the findings of the previous studies.[9] Higher CTR value in females was probably due to the smaller MITW, which is the natural body habitus.

Our finding of mean MITW and MTCD of 28.48 cm and 13.03 cm, respectively, for the general population were believed to be normal, and is consistent with that reported in Ghana by Mensah et al.[6] Our study also found that the mean values of MITW and MTCD in males (30.39 cm and 13.71 cm, respectively) were significantly higher than that in females (27.07 cm and 12.47 cm, respectively), which is consistent with that reported by Mensah et al.[6]

In the present study, CTR value increased with age up to the fourth decade and then decreased; this correlated well with the findings of some studies.[6],[10] On the contrary, Yousef et al.[11] reported that CTR value decreases with age. Our study also found that MITW and MTCD do not increase with the individual's age. This finding is contrary to earlier studies which reported that MITW and MTCD gradually increase with age up to the fourth decade.[6],[10] The decrease in MITW at an older age is due to reduced rib cage mobility and compliance.

The limitation of this study is that radiographs of apparently healthy controls were used in the study. However, the absence of symptoms does not necessarily mean the absence of disease.


  Conclusion Top


The result of this study has established the CTR of Nigerian population in Maiduguri. There was no significant difference between males and females in CTR. However, there was a significant difference between males and females in both MITW and MTCD. The CTR of females is slightly higher than that of males, and the MITW and MTCD of males are higher than that of females. CTR of the general population increases with age up to the fourth decade. Therefore, establishing normal ranges of CTR is necessary for comparison in a condition where a possible cardiac disease is being examined.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Kearney MT, Fox KA, Lee AJ, Prescott RJ, Shah AM, Batin PD, et al. Predicting death due to progressive heart failure in patients with mild-to-moderate chronic heart failure. J Am Coll Cardiol 2002;40:1801-8.  Back to cited text no. 1
    
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Collins J, Stern EJ. Chest Radiology, the Essentials. 2nd ed., Ch. 10. Philadelphia: Lippincott Williams & Wilkins; 2007.  Back to cited text no. 2
    
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Novelline RA. Squire's Fundamentals of Radiology. 6th ed. Cambridge, USA: Harvard University Press; 2004.  Back to cited text no. 3
    
4.
Perez AA, Ribeiro AL, Barros MV, de Sousa MR, Bittencourt RJ, Machado FS, et al. Value of the radiological study of the thorax for diagnosing left ventricular dysfunction in Chagas' disease. Arq Bras Cardiol 2003;80:208-13, 202-7.  Back to cited text no. 4
    
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Kadhum AA, Sharif S, Abd-Hazaa M. Validity of chest X-Ray in the estimation of cardiac size in comparison to echocardiography. MJBU 2007;25:48-51.  Back to cited text no. 5
    
6.
Mensah YB, Mensah K, Asiamah S, Gbadamosi H, Idun EA, Brakohiapa W, et al. Establishing the cardiothoracic ratio using chest radiographs in an indigenous Ghanaian population: A simple tool for cardiomegaly screening. Ghana Med J 2015;49:159-64.  Back to cited text no. 6
    
7.
John EE, Stephen DP, Peter OB, Anil US, Mohammed H, Emmanuel O, et al. Cardiothoracic ratio and body mass index in normal young adult Nigerians. J Trop Med 2014;16:47-51.  Back to cited text no. 7
    
8.
Moawia G, Mosleh A, Mohamed Y, Wedyan N, Amir M, Suliman S, et al. Evaluation of cardiothoracic ratio of normal subjects in Al Madinah Al Munawwara using chest radiographs. Pensee J 2017;76:374-85.  Back to cited text no. 8
    
9.
Obikili EN, Okoye IJ, Anyanwu GE. Cardiothoracic ratio in normal Nigerian subject. Biomed Res 2010;21:195-8.  Back to cited text no. 9
    
10.
Shirani S, Samie-Nasab M, Samimi K, Forouzandeh M, Khosravi A. Comparison of sensitivity and specifcity of cardiac size estimation through plain chest X-ray and two echocardiography. ARYA Atheroscler 2012; 7(Suppl): S1-4.  Back to cited text no. 10
    
11.
Yousef M, Gameraddin M, Mohammed A, Ahmed B. Aortic and heart dimensions in adults in Sudanese population using chest X-ray. Wulfenia J 2014;4:119-28.  Back to cited text no. 11
    


    Figures

  [Figure 1], [Figure 2]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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