Nonaneurysmal perimesencephalic subarachnoid hemorrhage on noncontrast head CT: An accuracy, inter-rater, and intra-rater reliability study.

BACKGROUND AND PURPOSE: To evaluate the reliability and accuracy of nonaneurysmal perimesencephalic subarachnoid hemorrhage (NAPSAH) on Noncontrast Head CT (NCCT) between numerous raters. MATERIALS AND METHODS: 45 NCCT of adult patients with SAH who also had a catheter angiography (CA) were independently evaluated by 48 diverse raters; 45 raters performed a second assessment one month later. For each case, raters were asked: 1) whether they judged the bleeding pattern to be perimesencephalic; 2) whether there was blood anterior to brainstem; 3) complete filling of the anterior interhemispheric fissure (AIF); 4) extension to the lateral part of the sylvian fissure (LSF); 5) frank intraventricular hemorrhage; 6) whether in the hypothetical presence of a negative CT angiogram they would still recommend CA. An automatic NAPSAH diagnosis was also generated by combining responses to questions 2-5. Reliability was estimated using Gwet's AC1 (κG), and the relationship between the NCCT diagnosis of NAPSAH and the recommendation to perform CA using Cramer's V test. Multi-rater accuracy of NCCT in predicting negative CA was explored. RESULTS: Inter-rater reliability for the presence of NAPSAH was moderate (κG = 0.58; 95%CI: 0.47, 0.69), but improved to substantial when automatically generated (κG = 0.70; 95%CI: 0.59, 0.81). The most reliable criteria were the absence of AIF filling (κG = 0.79) and extension to LSF (κG = 0.79). Mean intra-rater reliability was substantial (κG = 0.65). NAPSAH weakly correlated with CA decision (V = 0.50). Mean sensitivity and specificity were 58% (95%CI: 44%, 71%) and 83 % (95%CI: 72 %, 94%), respectively. CONCLUSION: NAPSAH remains a diagnosis of exclusion. The NCCT diagnosis was moderately reliable and its impact on clinical decisions modest.

Delayed Gadolinium Leakage in Ocular Structures on Brain MR Imaging: Prevalence and Associated Factors.

BACKGROUND AND PURPOSE: Gadolinium leakage in ocular structures (GLOS) is characterized by hyperintense signal in the chambers of the eye on FLAIR and has been reported in association with blood-ocular barrier breakdown in patients with ischemic strokes. The underlying mechanism of GLOS remains poorly understood; however, some studies suggest it may be part of a physiologic excretion pathway of gadolinium. This study aimed to determine the prevalence of GLOS in an unselected patient population. MATERIALS AND METHODS: A retrospective analysis was conducted on 439 patients who underwent brain MR imaging within 7 days of receiving a gadolinium-based contrast agent injection for a prior MR imaging study. Clinical, imaging, and laboratory data were collected. Descriptive and logistic regression analyses were performed. RESULTS: GLOS was observed in 26 of 439 patients (6%). The occurrence of GLOS varied with time, with 3 (12%), 14 (54%), 8 (31%), and 1 (4%) patient showing GLOS within 24, 25-72, 73-120, and >120 hours after gadolinium-based contrast agent injection, respectively. Patients with GLOS were older (median age: 72 versus 55 years, P = .001) and had higher median serum creatinine levels (73 versus 64 µmol/L, P = .005) and a lower median estimated glomerular filtration rate (84 versus 101 mL/min/1.73 m2, P < .001). A shorter median time interval between gadolinium-based contrast agent injection and the index brain MR imaging was observed in the group positive for GLOS (62 versus 91 hours, P = .003). Multivariable regression analysis identified the estimated glomerular filtration rate (OR = 0.970; 95% CI, 0.049-0.992; P = .008) and time interval since gadolinium-based contrast agent injection (OR = 0.987; 95% CI, 0.977-0.997; P = .012) as independent factors associated with GLOS. CONCLUSIONS: GLOS was observed in only a small percentage of patients receiving gadolinium-based contrast agent within 7 days before brain MR imaging. This phenomenon was noted in patients with normal findings on brain MR imaging and those with various CNS pathologies, and it was associated with lower estimated glomerular filtration rates and shorter time intervals after gadolinium-based contrast agent injection. While GLOS may be a physiologic gadolinium-based contrast agent excretion pathway, the presence of ocular disease was not formally evaluated in the included population. Awareness of GLOS is nonetheless useful for appropriate radiologic interpretation.

Increased rate of significant findings on brain MRI during the early stage of the COVID-19 pandemic.

OBJECTIVES: To assess the effect of the COVID-19 pandemic on the proportion of abnormal paediatric neuroimaging findings as a surrogate marker for potential underutilisation. METHODS: Consecutive paediatric brain MRIs performed between March 27th and June 19th 2019 (Tbaseline) and March 23rd and June 1st 2020 (Tpandemic) were reviewed and classified according to presence or absence and type of imaging abnormality, and graded regarding severity on a 5-point Likert scale, where grade 4 was defined as abnormal finding requiring non-urgent intervention and grade 5 was defined as acute illness prompting urgent medical intervention. Non-parametric statistical testing was used to assess for significant differences between Tpandemic vs. Tbaseline. RESULTS: Fewer paediatric MRI brains were performed during Tpandemic compared to Tbaseline (12.2 vs 14.7 examinations/day). No significant difference was found between the two time periods regarding sex and age (Tbaseline: 557 females (44.63%), 7.95 ± 5.49 years, Tpandemic: 385 females (44.61%), 7.64 ± 6.11 years; p = 1 and p = .079, respectively). MRI brain examinations during Tpandemic had a higher likelihood of being abnormal, 41.25% vs. 25.32% (p<.0001). Vascular abnormalities were more frequent during Tpandemic (11.01% vs 8.01%, p = .02), congenital malformations were less common (8.34% vs 12.34%, p = .004). Severity of MRI brain examinations was significantly different when comparing group 4 and group 5 individually and combined between Tbaseline and Tpandemic (p = .0018, p < .0001, and p <.0001, respectively). CONCLUSIONS: The rate of abnormality and severity found on paediatric brain MRI was significantly higher during the early phase of the pandemic, likely due to underutilisation.

PREDICT: Precise deployment of Silk Vista Baby in confined territory: A technical note.

Flow diverters (FD) have become increasingly useful in treating complex intracranial aneurysms, particularly wide-necked and recurrent aneurysms. Their use has progressively expanded to smaller vessels beyond the circle of Willis (CoW), and Silk Vista Baby (SVB) is one such low-profile FD which stands out because of deliverability through a 0.017″ microcatheter and smoother navigability. Precise deployment of SVB, specifically, the proximal end, can be challenging in certain anatomical locations when the proximal landing zone is very short, limited by vessel bifurcation or important branches arising from the artery or its geometry. We present our series to describe our technique and rule to 'PREDICT' the final deployment of SVB in real time, and discuss the nuances, exceptions and bail-out strategies. Using this technique, we were able to precisely deploy SVB in distal intracranial vessels with a mean proximal landing zone as short as 2.6 mm in 80% instances, requiring bail-out strategies in only 20% cases. This rule can be reliably followed in treating complex intracranial aneurysms with SVB FD within a confined territory, until validated software-based real-time planning tools are developed.

Venous outflow stenting for symptomatic developmental venous anomaly.

Developmental venous anomaly (DVA) is one of the commonest vascular malformations in the brain but rarely symptomatic. Various pathomechanisms such as mechanical compression, increased in-flow into DVA or outflow obstruction have been described as causative factors in symptomatic DVAs. We report a unique case of a pontomedullary DVA with venous outflow obstruction causing progressive neurological worsening in a young adult despite anticoagulation, who was treated with a novel approach of venous outlet stenting of the collector vein with favorable outcome. In carefully selected cases, this endovascular treatment can be an effective and safe alternative when other measures fail.

Capacity for paediatric radiology in Nigeria: a survey of radiologists.

Children account for nearly half the population of Nigeria yet the capacity for effective imaging of children is unknown. In order to determine clinical resources for and challenges of paediatric radiology in Nigeria, certified radiologists at an exit examination in radiology for resident doctors, and resident doctors in radiology attending an update course, completed a semi-structured questionnaire detailing personal information, radiology training, practice and perceived priorities of paediatric radiology in Nigeria. Of 100 questionnaires, 80 were returned, completed (80%) by 46 (58%) certified radiologists, 14 (18%) senior and 20 (25%) junior radiology residents. Only 1 (2.2%) certified radiologist received dedicated albeit short training in paediatric radiology. Nine (20.0%) certified radiologists and 1 (2.9%) resident doctor target their practice to paediatric imaging. Only 2 (4.4%) certified radiologists devote at least half of their time to paediatric radiology. Forty-two (91%) of the certified radiologists are not aware of any radiologist primarily affiliated with a dedicated children's hospital or who practices in a dedicated paediatric unit of a mixed hospital. Eight (19%) radiologists work in a facility with a consultant who has some training in paediatric radiology. Surgeons (64%), neonatologists (53%) and neurologists (45%) were the other paediatric specialties usually available where the respondent works. Fourteen (4.9%), 4 (2.1%), and 1 (1.3%) ultrasound, X-ray and magnetic resonance imaging (MRI) units, respectively, were reserved for paediatric imaging while no fluoroscopy or computed tomography (CT) unit was dedicated to children. Lack of dedicated equipment (44%) and trained paediatric radiologists (24%) were the main challenges to paediatric imaging as perceived by the respondents. Substantial deficits in human and material resources require informed investment in dedicated equipment and training to boost capacity for paediatric radiology in Nigeria.

Normative references and clinical correlates of fetal umbilical artery Doppler indices in southwestern Nigeria.

OBJECTIVE: To derive normative references for umbilical artery (UA) Doppler indices, including pulsatility index (PI), resistance index (RI), and systolic/diastolic (SD) ratio, for singleton pregnancies in Ile-Ife, Nigeria, and compare them with reference values from other populations. METHODS: A longitudinal study involving 415 women with a singleton fetus at 26-40 gestational weeks attending Obafemi Awolowo University Hospital, Ile-Ife, between July 2015 and March 2019. Fetal UA PI, RI, and SD ratio were measured every 4 weeks until delivery. Reference values from the 2.5th to the 97.5th centiles were derived from 1375 measurements. Correlations between indices and bio-demographic characteristics were assessed; regression equations were generated. RESULTS: The RI, PI, and SD ratio decreased by 0.013, 0.027, and 0.71, respectively, for each additional week of pregnancy. There was a negative correlation between the three indices and birthweight (P<0.001), but not maternal parity, age, or fetal gender. Regression equations for RI, PI, and SD ratio were, respectively, 1.004 - 0.013x, 1.78 - 0.027x, and 4.77 - 0.71x, where x is gestational age (weeks). CONCLUSION: The derived normative references for fetal UA Doppler indices are recommended for monitoring high-risk pregnancies in Nigeria. The indices are comparable to those derived from Norwegian, Thai, and British cohorts.

Normal ultrasonographic dimensions of the gallbladder and common bile duct in neonates

Background: Ultrasound (US) is the first choice of imaging in neonates presenting with persistent jaundice to exclude surgically correctable causes and differentiate obstructive from nonobstructive causes. Previous studies on normal dimensions of gallbladder (GB) and common bile duct (CBD) recruited adults and children spread across a wide age group.Aims: This study aimed to determine GB and CBD normal dimensions in a large homogeneous neonatal population as well as guide decision regarding pre-US fasting in neonates who require GB evaluation.Materials and Methods: Five hundred and twenty-eight healthy newborns were recruited between May 2009 and May 2011. The widest intraluminal anterior-posterior diameters of GB and CBD were measured. Neonatal age in days, sex, birth weight, weight and height, gestational age at delivery, and time interval since last feed recorded.Results: The mean age was 9.56 ± 7.66 days, and 50.6% were males. The mean CBD diameter was 1.16 ± 1.61 mm while the mean GB diameter was 4.42 ± 2.16 mm. GB and CBD were clearly seen and measurable in 297 (55.8%) neonates and 237 (44.38%) neonates, respectively. There was a significant correlation between CBD diameter and GB diameter (P = 0.04) but no correlation with any demographic parameter. GB visualization was not dependent on time interval from last feed.Conclusion: Mean neonatal values for CBD and GB were established, but neonates have a wider range of GB diameters compared with older children, so GB diameter may not be a reliable parameter for neonatal GB pathologies. GB visualization was not dependent on time interval from last feed; hence, a recent feed should not delay emergency scans, especially in ill neonates

Intracranial Arterial Calcification in Black Africans with Acute Ischaemic Stroke.

BACKGROUND: Intracranial arterial calcification (IAC), a recognized marker of atherosclerosis on cranial computed tomography (CT), is an independent risk factor for ischaemic stroke. This study aimed to determine the prevalence, distribution, severity, and associations of IAC in adults with acute ischaemic stroke (AIS) at the University College Hospital, Ibadan, Nigeria. METHODS: Cranial CT images of 130 consecutive adults who presented with AIS were acquired on a 64-slice multi-detector Toshiba Aquilion scanner and evaluated for IAC in bone window on Vitrea® software using a semi-quantitative scoring method for extent, thickness, and length of calcifications in the large intracranial arteries. Associations of IAC with clinical and laboratory data were determined by statistical analysis at p < 0.05. RESULTS: There were 71 males (54.6%), and the mean age of all patients was 63.0 ± 13.2 years. Hypertension was the most common risk factor (83.1%). IAC was found in 121 patients (93.1%), predominantly in the carotid siphon (86.1%) followed by the intracranial vertebral arteries (9.3%), middle cerebral arteries (2.4%), basilar artery (1.2%), and the anterior cerebral arteries (1%). The burden of IAC ranged from mild (17.4%) to moderate (52.1%) to severe (30.6%). Age (p < 0.001), diastolic blood pressure (p = 0.037), and alcohol use (0.046) were significantly different among the patients with mild, moderate, and severe degrees of IAC. IAC was associated with age (p < 0.001), hypertension (p = 0.03), diabetes mellitus (p = 0.02), hyperlipidaemia (p = 0.04), and alcohol use (p < 0.001) but not with sex (p = 0.35). CONCLUSIONS: The burden of IAC is very high among native African patients with AIS and preferentially involves proximal inflow arteries. Therefore, the role of large vessel atherosclerosis in ischaemic stroke in native Africans should be explored in future multinational, multimodality studies.

Brain and spine imaging artefacts on low-field magnetic resonance imaging: Spectrum of findings in a Nigerian Tertiary Hospital.

BACKGROUND: Low-field (LF) magnetic resonance imaging (MRI) is a technology that is widely used in resource-limited settings for clinical imaging. The images produced, even though of low resolution with noise and artefacts, provide valuable information and guidance for patient assessment and treatment. This study shows a spectrum of MRI artefacts that affect image quality during routine clinical neuroradiology practice using LF MRI in a Nigerian hospital and suggests ways to avoid them. MATERIALS AND METHODS: We retrospectively reviewed brain and spine MRI studies performed on a 0.36T MagSense 360 (Mindray, China) open MRI at our hospital over a 2-year period to identify image artefacts. About 90% of MRI studies performed at our facility during the study period were neuroimaging. The pattern and distribution of artefacts that featured during imaging were described and illustrative cases demonstrated highlighting their causes and ways to avoid or limit them. RESULTS: Of 936 brain and spine cases evaluated, 506 (54.1%) had artefacts with 369 (72.9%) seen in the brain. Truncation/Gibbs (37.6%) and motion (20.6%) were the most common artefacts in the series, seen most commonly in T2-weighted images. There was no significant difference in the proportion of artefacts between adults and children (P = 0.736). CONCLUSION: Artefacts are relatively common in neuroimaging with LF MRI and may potentially degrade image quality and interfere with accurate radiological reporting and diagnosis. Improving the recognition of LF MRI artefacts may assist imaging practitioners to avoid or limit their effect on image quality and interpretation.

Infections of the spine and spinal cord.

Predisposing factors for developing spinal infections include: immunodeficiency; drug abuse; the widespread use of broad-spectrum antibiotics, corticosteroids, and immunosuppressive drugs; diabetes mellitus; and spinal surgery. Infections can be bacterial, fungal, parasitic, or viral in origin. This chapter reviews current knowledge in clinical and imaging findings in the most common spinal infections divided according to the compartment primarily involved.

Maternal ophthalmic artery Doppler velocimetry in pre-eclampsia in Southwestern Nigeria.

BACKGROUND: Pre-eclampsia (PE) poses a serious challenge to maternal and fetal health in Africa. It is associated with hemodynamic changes that may affect the internal carotid/ophthalmic artery circulation with consequent neuro-ophthalmic manifestations. Ophthalmic artery Doppler (OAD) ultrasound is an important tool that can be used to detect hemodynamic changes in PE and monitor its severity. In this study, we evaluated hemodynamic changes on OAD ultrasound in the ophthalmic arteries of pre-eclamptic women and compared these with values in healthy pregnant women. METHODS: OAD parameters, such as, peak systolic velocity, peak diastolic velocity, end diastolic velocity, pulsatility index, and peak ratio, were measured on transorbital triplex ultrasound scan with a 7-10 MHz multifrequency linear transducer in 42 consenting pre-eclamptic patients and 41 pregnant controls matched for maternal age, gestational age, and parity at the Department of Radiology, University College Hospital, Ibadan. Univariate, bivariate, and receiver operating characteristic curve data analyses were performed. P<0.05 was considered to be statistically significant. RESULTS: Mean resistivity index, pulsatility index, and peak systolic velocity were significantly lower in pre-eclamptic patients than in the controls. Mean peak diastolic velocity, end diastolic velocity, and peak ratio were significantly higher in the pre-eclamptic group. The receiver operating characteristic curve showed that the resistivity index (sensitivity 75%, specificity 77.8%) could distinguish mild from severe PE while the peak ratio (sensitivity 90.5%, specificity 81.3%) could accurately detect PE. CONCLUSION: OAD ultrasound can be used to monitor patients with PE for early detection of progression to severe forms before cerebral complications develop. OAD screening of patients at high risk for PE can also detect early changes of hemodynamic derangement.

Incidental cranial CT findings in head injury patients in a Nigerian tertiary hospital.

BACKGROUND: Incidental findings on computed tomography (CT) scans are occasionally noted in patients presenting with head injury. Since it can be assumed that head injured patients are of normal health status before the accident, these findings may be a representation of their frequency in the general population. Our aim was to determine the prevalence of such incidental findings among head injured patients in Nigeria's foremost center of clinical neurosciences. MATERIALS AND METHODS: We conducted a retrospective review of CT scan images of 591 consecutive eligible patients over a 5-year period (2006-2010) to identify incidental findings. The images were evaluated by consensus agreement of two radiologists. Associations with gender and age were explored using appropriate statistical tests with an alpha level of 0.05. RESULTS: The mean patient age was 34.6 ± 21.2 years, and male to female ratio was 3.2: 1. Incidental findings were noted in 503/591 (85.1 %) of the scans. Intracranial calcification was the commonest finding occurring in 61.8% of patients. Over 90% of the findings were benign. Compared with older ones, patients under the age of 60 were less likely, (P < 0.001), to have incidental findings. CONCLUSION: Although the majority of incidental findings in this African cohort of head injury patients are benign some clinically significant lesions were detectable. It is therefore recommended that such findings be adequately described in the radiological reports for proper counseling and follow-up.

ROLE OF TRANSCRANIAL COLOUR-CODED DUPLEX SONOGRAPHY IN STROKE MANAGEMENT - REVIEW ARTICLE.

The development of transcranial colour-coded duplex sonography (TCCS) has resurrected the hope of safe, real time bedside brain imaging beyond childhood. This review article provides an overview of the role of TCCS in the management of patients with stroke. The objective is to stimulate interest in the field of neurosonology as a potential means of improving neurological outcome for stroke patients and a area for stroke research endeavors in Africa. Literature search was done on MEDLINE, Cochrane library, and Google Scholar databases with the following keywords: transcranial colour Doppler, Transcranial duplex sonography, transcranial colour-coded Doppler sonography, stroke, infarct and haemorrhage. We also identified relevant articles from the references section of studies produced by our literature search. We discussed the roles of TCCS to discriminate ischaemic from haemorrhagic forms; unravel the mechanism of stroke; monitor temporal evolution of stroke and predictors of stroke outcome; and promote better understanding of the epidemiology of stroke. Its emerging role as a potent point-of-care imaging modality for definitive treatment in ischaemic stroke within and outside the hospital setting is also highlighted. Comparison of TCCS with alternative modalities for neuroimaging in stroke is also discussed. A root cause analysis of the untenable high cost of neuroimaging for stroke patients in Africa is presented vis-à-vis the potential economic relief which widespread adoption of TCCS may provide. We advocate capacity building for TCCS and suggest some action plans required to achieve safe, cheap, affordable and reliable ultrasound based neuroimaging for stroke patients in resource limited areas of Africa.