The Artery of Percheron (AOP) is an uncommon anatomic variant that provides arterial supply to the paramedian region of the thalami and bilaterally to the rostral part of the midbrain; it is a solitary arterial trunk that branches from a proximal segment of the posterior cerebral artery (PCA). Although AOP infarction results in a characteristic pattern of ischemia, namely bilateral paramedian thalamic infarct with or without midbrain involvement, it may cause diagnostic difficulties due to the variety of its clinical presentations and wide differentials, as well as its small diameter and the difficulty of obtaining visualization through diagnostic imaging. Early neuroimaging of AOP infarction and correct diagnosis are mandatory for early initiation of the appropriate treatment and better patient outcomes. This study discusses the imaging patterns and imaging differentials of AOP infarction and its clinical presentation. A 55-year-old man presented to the emergency department unconscious with Glasgow Coma Scale score of 4. Pupillary light reflex on both eyes was poorly reactive with dilatated right pupil. The patient flexed his arm and extended his leg on painful stimulus. Laboratory tests and electrocardiogram were unremarkable. Emergency cerebral CT scan and transcranial Doppler ultrasound were normal. He gradually regained consciousness with residual somnolence, ptosis, and vertical gaze palsy. Second CT scan showed bilateral paramedian thalamic areas of hypodensity, CT angiography (CTA) was unremarkable. MRI showed bilateral high-signal intensity on paramedian thalami fast spin echo T2, FLAIR, and diffusion-weighted sequences, low signal on apparent diffusion coefficient sequence. MR angiography (MRA) revealed an abnormal tiny vessel arising from the P1 segment of the left posterior cerebral artery. Imaging findings were consistent with AOP infarction. Aspirin was started, 4 hours after admission the patient regained consciousness, and gradually improved on the following days till he was discharged on the 15th day, with mild neurologic deficit. AOP must be considered whenever paramedian thalamic infarction is noted in neuroimaging. The difficulty in visualizing the AOP using diagnostic imaging is due to its small diameter, leading to the limited abilities of MRA and CTA to diagnose AOP infarction. An absence of evidence of AOP infarction in MRA or even CTA does not exclude its diagnosis. Good knowledge of the imaging characteristics of AOP infarction will help in early diagnosis and the achievement of good patient outcomes.

: The Artery of Percheron (AOP) is an uncommon anatomic variant that provides arterial supply to the paramedian region of the thalami and bilaterally to the rostral part of the midbrain; it is a solitary arterial trunk that branches from a proximal segment of the posterior cerebral artery (PCA). Although AOP infarction results in a characteristic pattern of ischemia—namely bilateral paramedian thalamic infarct with or without midbrain involvement— it may cause diagnostic difficulties due to the variety of its clinical presentations and wide differentials, as well as its small diameter and the difficulty of obtaining visualization through diagnostic imaging. Early neuroimaging of AOP infarction and correct diagnosis are mandatory for early initiation of the appropriate treatment and better patient outcomes. In this study, we discuss imaging the patterns of AOP infarction, as well as its differentials and clinical presentation.

Since the outbreak of Coronavirus Disease-19 (COVID-19) infection in December 2019 in Wuhan, the capital Hubei province, central of China, more than 4 million people have contracted the virus worldwide. Despite the imposed precautions, coronavirus disease-19 is rapidly spreading with human-to-human transmission resulting in more than 290,000 death as of May 13, 2020 according to World Health Organization (WHO). The aim of this study was to revise the characteristic imaging features of Sever Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) during their outbreak, and to compare them with that of COVID-19, to familiarize radiologists with the imaging spectrum of corona-virus syndromes. This study will help in more understanding and characterisation of COVID-19 to support the global efforts in combating its worldwide outbreak.

Introduction Radiation protection for pediatric patients is the main concern in pediatric computed tomography (CT) due to their sensitive organs, such as the brain and the thyroid glands. Accordingly, an optimization of pediatric CT practices is vital to minimize the radiation dose for this population. Aim To assess the pediatric CT practices of radiologists and technologists in a CT unit. Materials and Methods The study was conducted among 26 hospitals, located in various regions in Saudi Arabia. A total of 200 hard copies of the questionnaire were distributed manually and were collected for analysis. In total, 117 completed surveys were gathered from technologies, while 49 were gathered from radiologists. Results In the case of infants with hydrocephalus, 65% of the radiologists ordered an ultrasound (US), 24% ordered a head CT scan, and 10% ordered a magnetic resonance imaging (MRI) and general X-ray for diagnosis. For pediatric patients complaining of persistent headache, 59% and 27% of the radiologists recommended CT and MRI, respectively, for diagnosis. Conclusion Most of the radiologists utilize CT head scan to diagnose persistent headache (by 59%) and ventriculoperitoneal shunt (VPS) malfunction (by 41%) in pediatric patients compared with the other modalities. The use of CT can increase the risk of later malignancy among pediatric patients due to radiation exposure. Alternative imaging modalities such as US and MRI (non-ionized radiation) should be considered to reduce the ionizing radiation hazards and optimize the current practices of radiologists. Most of the technologists follow radiation protection protocols in this study as 63% of the technologists used lead apron for pediatric patient’s protection. Radiation awareness training for the technologists could improve the knowledge about the benefits of using lead apron and reduce the radiation risks in pediatric patients.

Computed tomography (CT) has had a massive impact on diagnostic radiology over the past few decades. Serious concerns exist because of the increase in the effective radiation dose associated with CT scans, which could pose significant health risks. In CT, the effective dose can be estimated by Monte Carlo simulations. The aim of the study was to estimate and compare the effective doses for CT from organ dose-based calculations using the tissue weighting factors of the International Commission on Radiological Protection publications (ICRP 60, 103), Monte Carlo CT-Expo v2.6, and dose-length product (DLP)-based estimates. For 165 CT scans, the effective doses (Ed) of the most common routine radiological investigations were assessed. There were 112 male patients (68%) and 53 female patients (32%). When compared to organ dose-based estimates, the DLP-based estimates of the effective dose produced by applying ICRP 60 coefficients were less than 55–57% (head) and more than 18.1% (chest) and 20% (abdomen). The ICRP 103 values of the Ed were less than 79% (head) and more than 17% (chest), and they changed randomly with the tissue weighting factors for the abdomen. For Monte Carlo CT-Expo, the Ed values were lower by 54% (head), 6% (abdomen), and more than 2% (chest) compared to organ dose-based estimates. Effective doses calculated using the tissue-weighting factors of ICRP 103 values comparable to ICRP 60 differ greatly by an average of 2.3, 2.9, and 4.5 mSv for the head, chest, and abdomen, respectively. In conclusion, all estimates of Ed are subject to the biases inflicted by the assumptions in the methods used; therefore, no significant agreement should be expected. The reason for evaluating ICRP 60 is to make a point that ICRP’s update is indeed more accurate. The variability associated with the use of various methodologies to estimate and compare the effective dose Ed in CT scans was shown to be significant in this study.