Original Article

Incidental Findings on Computerized Tomography Images of Trauma Cases

Cite this article as: Kaya A, Senol E, Eraslan C, Mert Karaca A, Durdagi E. Incidental findings on computerized tomography images of trauma cases. Arch Iran Med. 2022;25(9):624-633. doi: 10.34172/aim.2022.98

Introduction

Traumas can cause minor injuries or result in loss of organs and limbs or even death. Rapid and accurate determination of trauma-related symptoms helps with correct diagnosis and treatment, and also forensic processes.

Radiological imaging methods, which have become more specific with the developing technology, have a significant role in revealing the findings or diagnoses related to trauma. When the injuries related to trauma are defined by radiological methods, sometimes additional non-trauma-associated findings are also observed. In the literature, the frequency of incidental findings (IFs) varies between 30.6% and 53.0%.^1-3 Determination of incidental pathologies may be beneficial for the patient, such as for early diagnosis of cancer. Besides, redundant examinations for IFs that will not change the patient’s health status can cause unnecessary anxiety.^1,2

This study aimed to evaluate the characteristics of IFs on computed tomography (CT) scans of trauma admissions, examine the relationships of IFs with gender and age groups, and discuss the management strategies.

Materials and Methods

Participants

The medical documents of 3348 trauma cases, who were admitted to Ege University, Faculty of Medicine, Department of Forensic Medicine during the two-year period from January 1, 2017 to December 31, 2018, were retrospectively reviewed. For 1611 of them, CT scans were performed and reported by the Department of Radiology. Of these, 783 (48.6%) cases with IFs were included.

Cases who were followed up and treated in another center after traumatic injuries, those who did not undergo CT scan, and those without CT scan reports were excluded.

Data Management and Analysis

Online access to the CT reports was provided from the hospital information system. Gender, age at the time of the event, type of CT scans, type of injury, injured body regions, and IFs were evaluated. The cases were divided into five age groups (0–19, 20–39, 40–59, 60–79, 80 and over). Age was included in all analyses according to this categorization, but the numerical age was summarized only in the text with mean ± standard deviation and range as descriptive statistics.

All data were reported as frequencies and percentages with 95% confidence interval (CI) calculated using Wilson’s method.⁴ IBM SPSS Statistics 25.0 (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.) and R (R software, version 4.0.5, package: arsenal, R Foundation for Statistical Computing, Vienna, Austria; https://www.r-project.org/) were used for statistical analyses in this study. For all analyses, a P value less than 0.05 was considered statistically significant.

The Chi-square test (or its Monte Carlo P values) was used to assess the association between two categorical variables.⁵ The adjusted residuals were used to determine which cells were responsible for a significant Chi-square result on r × c tables.⁶ They are distributed approximately normally under the independence null hypothesis of the Chi-square test, so they were represented in the text with z-scores. Also, when a positive z-score is more than 1.96, it means that the observed frequency in that cell is more than expected. Additionally, the linear-by-linear association test was used when analyzing crosstabs of two ordinal variables (or ordinal vs. binary variable).

Classification of Incidental Findings

There are various classifications in the literature about IFs in imaging diagnostics tests.^1-3,7-15 In a study conducted in Iran, IFs on brain CT were divided into two groups: intracranial findings with and without clinical symptoms.⁷ In another study, IFs on whole-body CTs were classified in two groups as findings that require urgent intervention or further examination and findings that do not require further investigation.⁸ In a pediatric age group study, IFs detected on brain CT were classified into three groups: requiring immediate evaluation and treatment, requiring outpatient follow-up, and not requiring specific follow-up or intervention.⁹

In this study, considering the classifications used in the literature,^7-9 IFs were classified into three groups:

• Group 1: Findings that do not require further investigation, congenital anomalies, and non-degenerative or minor degenerative findings.

• Group 2: Findings that do not require immediate intervention, require outpatient follow-up, or require follow-up or treatment in case of symptoms.

• Group 3: Findings that require immediate intervention or further investigation.

Results

Of the 783 cases included in this study, 606 (77.4%) were male and 177 (22.6%) were female. The mean age was 41.63 ± 16.35 years (range 1–93 years).

The types of injuries were out-of-vehicle traffic accidents (n = 254, 32.4%; 95% CI, 29.3%-35.8%), in-vehicle traffic accidents (n = 212, 27.1%; 95% CI, 24.1%–30.3%), batteries (n = 170, 21.7%; 95% CI, 19.0%–24.7%), stab injuries (n = 43, 5.5%; 95% CI, 4.1%–7.3%), falls from heights (n = 33, 4.2%; 95% CI, 3.0%–5.9%), occupational injuries (n = 32, 4.1%; 95% CI, 2.9%–5.7%), and firearm injuries (n = 29, 3.7%; 95% CI, 2.6%–5.3%).

One or more (max. 5) injured body regions were observed in 783 patients. Also, there were a total of 1530 affected anatomical regions. Of these, the cranial region (n = 452, 29.5%; 95% CI, 27.3%–31.9%), lower extremities (n = 308, 20.1%; 95% CI, 18.2%–22.2%), chest (n = 283, 18.5%; 95% CI, 16.6%–20.5%), and upper extremities (n = 258, 16.9%; 95% CI, 15.1%–18.8%) were the most frequently injured regions. The associations between injured body region and the type of injury are shown in Table 1.

There were 2385 CT scans for 783 trauma cases included in this study. Cranial CT scan was performed in 85.4% (n = 669) of the cases, cervical CT scan in 80.2% (n = 628), whole-body CT scan in 70.0% (n = 548), extremity CT scan in 23.0% (n = 174), maxillofacial CT scan in 6.8% (n = 161), lumbar vertebral CT scan in 2.6 (n = 62), thoracic vertebral CT scan in 2.4% (n = 58), abdominal CT scan in 2.1% (n = 50), and chest CT scan in 1.5% (n = 35). The number of CT scans with IFs was 1197 (50.2%) in this study, with 342 CT scans exhibiting > 1 IF (201 exhibiting 2, 74 exhibiting 3, 39 exhibiting 4, and 28 exhibiting ≥ 5 findings). The number of cases with IFs on these CT scans was 312.

A total of 1802 IFs were observed in 783 cases. There was more than one IF in 453 cases. The percentage of IFs was 75.6% (n = 1363; 95% CI, 73.6%–77.6%) for males and 24.4% (n = 439; 95% CI, 22.4%–26.4%) for females, and it was 4.8% (n = 85; 95% CI, 3.8%–5.8%), 27.6% (n = 498; 95% CI, 25.6%–29.7%), 44.3% (n = 800; 95% CI, 42.1%–46.7%), 20.9% (n = 377; 95% CI, 19.1%–22.9%) and 2.4% (n = 42; 95% CI, 1.7%–3.1%) for each respective age group. The three body regions with the highest incidence of incidental pathologies were the abdominopelvic (n = 605, 33.6%; 95% CI, 31.4%–35.8%), head & neck (n = 426, 23.6%; 95% CI, 21.7%–25.7%), and spinal column & cord region (n = 352, 19.5%; 95% CI, 17.8%–21.4%), respectively. Furthermore, 5.4% (n = 98) of the IFs were congenital and 94.6% (n = 1704) were acquired.

Incidental findings in the head and neck region were significantly higher in males (P < 0.001, χ²=12.343). There was no statistically significant difference in other regional IFs according to gender.

In terms of the organs, the IFs detected in the thyroid, and gall bladder & bile ducts were significantly higher in females (P = 0.044, χ² =4.043; P < 0.001, χ² =12.456). The distribution of IFs detected in organs/systems by gender is shown in Table 2.

The comparison of IFs detected in organs/systems according to age groups is shown in Table 3. The rate of IFs in the liver, kidney, adrenal gland, and vascular structures increased significantly with age (P = 0.011, P < 0.001, P = 0.004, P < 0.001, respectively).

The most common IF was degenerative changes in the vertebrae (n = 288, 36.8%; 95% CI, 33.5%–40.2%), followed by sinusitis (n = 203, 25.9%; 95% CI, 23.0%–29.1%), renal cyst (n = 131, 16.7%; 95% CI, 14.3%–19.5%) and lung nodule (n = 97, 12.4%; 95% CI, 10.3%–14.9%).

According to the classification of IFs, there were 624 group 1 findings (34.6%; 95% CI, 32.5%–36.9%), 983 group 2 findings (54.6%; 95% CI, 52.2%–56.8%), and 195 group 3 findings (10.8%; 95% CI, 9.5%–12.3%). Incidental findings and their classifications are shown in Tables 4, 5, and 6.

The association of classification of IFs with gender, age groups, and body regions is shown in Table 7. The only significant association was between the classification of IFs and body regions (P < 0.001).

Discussion

In this study, in which IFs were analyzed in trauma cases, 77.4% of 783 cases were male, and the mean age was 41.63 ± 16.35. In a study about the IFs in pediatric trauma patients, 68.5% of the cases were male.¹⁴ In a study by Sierink et al on IFs in trauma cases older than 18 years, males constituted 71.7%.¹ In a similar study involving all age groups, the rate of males was 64.5%.² Since males are more involved in work and social life than females, and males are more likely to engage in risky behaviors, the risk of being exposed to trauma is higher in males. On the other hand, some studies^3,15 have reported that IFs are more common in females, andin some studies,^7,8,10,11 there was no statistically significant relationship between IFs and gender.These differences across studies may have resulted from variations in the studied groups.

In this study, the most common cause of trauma was traffic accidents, and out-of-vehicle traffic accidents were more common than in-vehicle traffic accidents. The widespread use of motor vehicles and non-compliance with traffic rules in Turkey may be a reason for this result. Statistically, thorax injuries in stab injuries and both thorax and spinal column & cord injuries in-vehicle traffic accidents were higher than expected. However, thorax injuries in batteries and spinal column & cord injuries in batteries and stab injuries were lower than expected. Similarly, lower extremity injuries were higher than expected in firearm injuries and out-of-vehicle traffic accidents, whereas they were lower than expected in batteries and in-vehicle traffic accidents. Also, cranial injuries were higher than expected in batteries, and lower than expected in falls from heights, stab injuries, out-of-vehicle traffic accidents and firearm injuries. Lastly, abdominal injuries were higher than expected in stab injuries. These data show that the type of trauma greatly affects the injured regions.

In the present study, the most frequently injured area was the cranial region, and the majority of the 2385 CTs were cranial (85.4%) and cervical vertebral CTs (80.2%). The most frequently injured area^16,17 and the most common types of CTs were compatible with the literature.^3,18 The reason for these should be that CT scans have advantages in rapidly detecting emergency interventions, especially for head and neck traumas. Besides, the high number of CTs may be due to defensive medical practices. Unfortunately, there has been an increase in medical malpractice claims in Turkey.

Approximately ¼ of cases (n = 453) had more than one IF consistent with the literature.^1,3,10-13,18 Besides, as per the literature, IFs in the abdominopelvic region were the most common findings in trauma cases.^1,3,10,11,18 Due to the presence of many organs in this region, the number of IFs detected in this region should be high.

In the present study, the most common IFs were degenerative changes in the vertebrae, sinusitis, kidney cyst, and lung nodule, respectively. In the literature, the most common IFs were renal cysts,^1,3,12,18 degenerative changes in the spine,^2,13 and calcifications in the brain.¹¹ Although the results of this study are generally compatible with the literature, some studies did not include IFs such as degenerative joint diseases, sinusitis, and age-related cerebral atrophy; in other words, the differences in the inclusion and exclusion criteria across studies might have led to differences in their findings.

Incidental findings in the head and neck regions were significantly higher in males. Also, IFs of the thyroid, gallbladder, and bile ducts were significantly higher in females. There have been studies showing a gender relationship with tumors and diseases of the mentioned regions and organs. Since male smokers continue to outnumber female smokers and oral HPV infection is more frequent in males, head and neck cancer is more common among males.^19,20 On the other hand, gall bladder and biliary diseases and thyroid problems have been 5 to 8 times more common in females, with pregnancy, estrogen, hormone replacement therapies in postmenopausal women and oral contraceptives noted as risk factors.^21-23 These results are in line with the literature. However, when the classification of IFs was compared by gender, no statistically significant difference was found (P = 0.573).

In this current study, the IFs especially in the vascular system, kidney, adrenal gland, prostate, and heart increased significantly with age. A statistically significant difference was observed between age groups and the classification of IFs (P = 0.430). Incidental findings in group 2 gradually decreased with increasing age, but IFs in group 1 and 3 increased with aging. The 40–59 years age group had the highest rates for group 1, 2 and 3. In similar studies, the incidence of IFs increased with age.^2,7,11,18 Also, Kroczek et al stated that the severity of IFs (findings requiring urgent treatment/further investigation) rose with increasing age.¹⁰

In the literature, there are several classification or scoring systems for IFs due to their clinical significance.^1-3,7-15 In this current study, IFs were classified into three groups, based on the literature. More than half of the IFs (54.6%) were in group 2, and approximately 1/3 (34.6%) were in group 1. The relationship between the classification of IFs and body regions of the pathologies was statistically significant (P < 0.001). Vertebral pathologies were mostly observed to be in group 1, while abdominopelvic pathologies mostly fell in groups 2 and 3. Knowing this relationship can be a guide for physicians in evaluating and managing the process of IFs. In the literature, most of the IFs on CT scans were findings that do not require emergency intervention.^{2,3,8-11,13,18} Since IFs in group 3 are signs of malignancy, metastatic disease, or vascular aneurysm, early detection of these findings will reduce mortality and morbidity. Providing appropriate information to patients about the detected IFs will help prevent confusion and unnecessary examinations that may occur in the diagnosis and treatment process.³

Nevertheless, many IFs may not be considered during the evaluation of traumatic cases but may be essential for the patient’s health in general. In cases investigated for trauma, IFs are more likely to be overlooked due to a greater focus on traumatic injuries. Also, there may be medicolegal issues in verifying the verbal information given to trauma patients. For these reasons, it is essential to pay attention to proper documentation, to give adequate and appropriate information, and to follow up on the cases.

This study has some limitations. The current study was performed in a single center, so the results may not be applicable to other centers. There is not any standard classification of IFs in the literature. For this reason, a classification was developed based on the literature. Some IFs might not have been reported by radiologists when the trauma findings were more vital in some cases. There were not any medical records to show that information was given to the patients about the IFs, or recommendation of treatment, follow-up, or further tests. Therefore, information rates or follow-up and treatment processes of the cases could not be evaluated. Besides, it is not known whether the cases were already followed up for IFs before the trauma.

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