The prevalence of undiagnosed abnormalities on non-contrast-enhanced computed tomography compared to contrast-enhanced computed tomography of the brain

Abstract

Background: Even though magnetic resonance imaging (MRI) is the gold standard investigation for intracranial pathology, it is not widely available in developing countries and computed tomography (CT) of the brain remains the first-line investigation for patients with suspected intracranial pathology. It is generally accepted that certain intracranial pathology can be missed on non-contrast-enhanced CT (NECT) of the brain if a contrast-enhanced CT (CECT) is not done. We have to consider on the one hand the risk of delayed or missed diagnosis and on the other hand the cost, increased radiation exposure and contrast-induced reactions. Advances in CT technology have also improved the resolution of CT scan images, making it easier to identify pathology on an NECT of the brain. To date, no study comparing NECT to CECT of the brain, utilising 64-slice CT technology, has been published.Objectives: To determine the prevalence of undiagnosed abnormalities on non-contrast-enhanced computed tomography (NECT) scans of the brain reported as normal, on a 64-slice CT scanner.Method: A descriptive retrospective study was undertaken of CT brain scans done during a 12-month period at a tertiary provincial hospital in the Northern Tshwane district of Gauteng, South Africa. The CT brain scans were evaluated by three reviewers (general radiologists). The NECT and contrast-enhanced computed tomography (CECT) scans of the brain were reviewed independently on separate occasions. Reviewers were blinded to patient history, each other’s interpretation, and to their own interpretation of the NECT when evaluating the CECT and vice versa. Discrepancies in interpretation were resolved during a consensus meeting between all three reviewers. The reviewers also re-evaluated the NECT scans of the cases with undiagnosed abnormal findings during this session. A decision was made pertaining to the visibility of the abnormal findings on the NECT scan.Results: In this study, 3.28% of cases had abnormal findings undiagnosed by three reviewers on the NECT scans. Re-evaluation by the panel reduced this to 1.42%, indicating a reading error of 1.85%.Conclusion: There is a small prevalence of missed abnormal findings on the NECT scan when using only NECT. Omitting unnecessary CECT will reduce the radiation exposure to the patient and reduce the risk of adverse events from the use of intravenous iodinated contrast. Alternatively, doing only a CECT scan would reduce the risk of missing abnormal findings and would also decrease the patient’s exposure to radiation.

Characteristics of Brain Imaging in Intracranial Tumor Patients at Neurology Ward Dr. Hasan Sadikin General Hospital Bandung 2017–2019

“…In this research, contrast CT-Scan (45.6%) was the most widely used Using a contrast CT scan is more advantageous than a single CT scan without contrast. Based on a retrospective study conducted in South Africa, 5 there is 3.28% of intracranial pathology that failed to be detected on the use of non-contrast CT without being followed by a contrast CT scan, for example, if there is blood-brain barrier damage. 5 Although a non-contrast CT scan can reduce operational costs, risk of allergic reactions, and risk of contrast-induced acute kidney injury, it requires careful assessment of the history of the disease.…”

“…Based on a retrospective study conducted in South Africa, 5 there is 3.28% of intracranial pathology that failed to be detected on the use of non-contrast CT without being followed by a contrast CT scan, for example, if there is blood-brain barrier damage. 5 Although a non-contrast CT scan can reduce operational costs, risk of allergic reactions, and risk of contrast-induced acute kidney injury, it requires careful assessment of the history of the disease. 5 Magnetic resonance imaging (MRI) is rated as the modality of choice with high contrast and spatial resolution for delineating intracranial tumor lesions compared to CT. 6 This is due to the working principle of MRI which utilizes electromagnetic signal emission at the level of the hydrogen atom nucleus in the human body.…”

“…5 Although a non-contrast CT scan can reduce operational costs, risk of allergic reactions, and risk of contrast-induced acute kidney injury, it requires careful assessment of the history of the disease. 5 Magnetic resonance imaging (MRI) is rated as the modality of choice with high contrast and spatial resolution for delineating intracranial tumor lesions compared to CT. 6 This is due to the working principle of MRI which utilizes electromagnetic signal emission at the level of the hydrogen atom nucleus in the human body. 6 According to the Panduan Penatalaksanaan Kanker Otak Tahun 2016 from the Ministry of Health of the Republic of Indonesia, 2 MRI should be the right method of choice to provide a good picture, especially for infratentorial lesions.…”