Factors Contributing to Attenuation of Cerebral Venous Sinus in Brain Noncontrast Computed Tomography Scan

Background/Aim In noncontrast computed tomography (NCCT), an apparently hyper-attenuated cerebral venous sinus (CVS) may lead to suspicion of CVS thrombosis. Understanding the factors affecting attenuation of CVS can guide us toward true diagnosis. Hence, the aim of the study was to determine the effect of different factors such as hematocrit, hemoglobin, age, blood urea nitrogen (BUN), creatinine, leukocyte and platelet count, and sex on the attenuation of CVS on brain NCCT. Material and Methods Total 1,680 patients were included in this study, and their demographic and laboratory data and brain NCCT were reviewed. In their brain NCCT, the average attenuation of superior sagittal sinus and both right and left sigmoid sinuses was measured. Data analysis was conducted using the Statistical Package for the Social Sciences version 21.0 software by Kolmogorov-Smirnov, Spearman's correlation coefficient, and multiple linear regression tests. The significance level was considered less than 0.05. Results Hematocrit (B = 0.251, p < 0.001), hemoglobin (B = 0.533, p < 0.001), and creatinine (B = − 0.270, p = 0.048) were determined as predictors of attenuation of superior sagittal sinus. For both sigmoid sinuses, hematocrit (p < 0.001) and hemoglobin (p < 0.001) were determined as positive predictors, and creatinine (p < 0.001) and BUN (p < 0.002) were determined as negative and positive predictors, respectively. Conclusion Hemoglobin, hematocrit, creatinine, and BUN are the main factors that should be considered in the assessment of CVS density on brain NCCT. As with increasing hematocrit and hemoglobin of the subject, the CVS density in NCCT increases, and with increasing creatinine and in some instance decreasing BUN of the subject, the CVS density in NCCT decreases.

MRI evaluation of cerebral metabolic rate of oxygen (CMRO2) in obstructive sleep apnea

Patients with obstructive sleep apnea (OSA) are at elevated risk of developing systemic vascular disease and cognitive dysfunction. Here, cerebral oxygen metabolism was assessed in patients with OSA by means of a magnetic resonance-based method involving simultaneous measurements of cerebral blood flow rate and venous oxygen saturation in the superior sagittal sinus for a period of 10 minutes at an effective temporal resolution of 1.3 seconds before, during, and after repeated 24-second breath-holds mimicking spontaneous apneas, yielding, along with pulse oximetry-derived arterial saturation, whole-brain CMRO2 via Fick’s Principle. Enrolled subjects were classified based on their apnea-hypopnea indices into OSA (N = 31) and non-sleep apnea reference subjects (NSA = 21), and further compared with young healthy subjects (YH, N = 10). OSA and NSA subjects were matched for age and body mass index. CMRO2 was lower in OSA than in the YH group during normal breathing (105.6 ± 14.1 versus 123.7 ± 22.8 μmol O2/min/100g, P = 0.01). Further, the fractional change in CMRO2 in response to a breath-hold challenge was larger in OSA than in the YH group (15.2 ± 9.2 versus 8.5 ± 3.4%, P = 0.04). However, there was no significant difference in CMRO2 between OSA and NSA subjects. The data suggest altered brain oxygen metabolism in OSA and possibly in NSA as well.

Venous cerebral blood flow quantification and cognition in patients with sickle cell anemia

Prior studies have described high venous signal qualitatively using arterial spin labelling (ASL) in patients with sickle cell anemia (SCA), consistent with arteriovenous shunting. We aimed to quantify the effect and explored cross-sectional associations with arterial oxygen content (CaO2), disease-modifying treatments, silent cerebral infarction (SCI), and cognitive performance. 94 patients with SCA and 42 controls underwent cognitive assessment and MRI with single- and multi- inflow time (TI) ASL sequences. Cerebral blood flow (CBF) and bolus arrival time (BAT) were examined across gray and white matter and high-signal regions of the sagittal sinus. Across gray and white matter, increases in CBF and reductions in BAT were observed in association with reduced CaO2 in patients, irrespective of sequence. Across high-signal sagittal sinus regions, CBF was also increased in association with reduced CaO2 using both sequences. However, BAT was increased rather than reduced in patients across these regions, with no association with CaO2. Using the multiTI sequence in patients, increases in CBF across white matter and high-signal sagittal sinus regions were associated with poorer cognitive performance. These novel findings highlight the utility of multiTI ASL in illuminating, and identifying objectively quantifiable and functionally significant markers of, regional hemodynamic stress in patients with SCA.

The fate of a Military Pilot in Malaysia: Lingering on the ground after young stroke

Strokes in young pilots can result in the devastating loss of productive years of life, especially for pilots at the peak of their careers. A 32-yr-old male military helicopter pilot was diagnosed with superior sagittal sinus thrombosis and bilateral parietal hemorrhages secondary to protein S deficiency after 15 years in military service. Two years post-stroke, he was carefully evaluated for a possible return to work after aeromedical assessment and the 1 percent rule being considered. A decision was made by the medical board for him to be disqualified to fly and grounded with work accommodation. The authors recommend that there is a need for reassessment up to two years using the objective PULHEEMS method for young pilots who failed aeromedical assessment due to stroke for returning to work as their experiences and knowledge is highly valuable.