Impact of Skull Defects on the Role of CTA for Brain Death Confirmation

Computed tomography angiography in the diagnosis of brain death: Implementation and results in Germany

BACKGROUND

Computed tomography angiography (CTA) has been investigated as a confirmatory study (CS) for the diagnosis of brain death (BD). International consensus regarding its use, study parameters, and evaluation criteria is lacking. In the German BD guideline, a CTA protocol was first introduced in 2015.

METHODS

The authors obtained a comprehensive dataset of all BD examinations in adults from the German organ procurement organization to investigate implementation, results, and impact of CTA on BD determination during the first 4 years.

RESULTS

In 5152 patients with clinically absent brain function, 1272 CTA were reported by 676 hospitals. Use of CTA increased from 17.2% of patients in the first year to 29.7% in the final year. CTA replaced other CS such as electroencephalography without increasing overall CS frequency. Technical failure was rare (0.9%); 89.3% of studies were positive. Negative results (9.8%) were more frequent with secondary brain injury, longer duration of the clinical BD syndrome, or unreliable clinical assessment. Median time to diagnosis was longer with CTA (2.6 h) versus other CS (1.6 h). CTA had no differential impact on the rate of confirmed BD and did not improve access of small hospitals to CS for BD determination.

CONCLUSIONS

CTA expands the range of available CS for the diagnosis of BD in adults. Real-world evidence from a large cohort confirms usability of the German CTA protocol within the guideline-specified context.

Self-harm, suicide and brain death: the role of the radiologist

Suicide is a leading cause of death worldwide and takes many forms, which include hanging, jumping from a height, sharp force trauma, ingestion/poisoning, drowning, and firearm injuries. Self-harm and suicide are associated with particular injuries and patterns of injury. Many of these patterns are apparent on imaging. Self-harm or suicidal intent may be overlooked initially in such cases, particularly when the patient is unconscious or uncooperative. Correct identification of these findings by the radiologist will allow a patient's management to be tailored accordingly and may prevent future suicide attempts. The initial role of the radiologists in these cases is to identify life-threatening injuries that require urgent medical attention. The radiologist can add value by drawing attention to associated injuries, which may have been missed on initial clinical assessment. In many cases of self-harm and suicide, imaging is more reliable than clinical assessment. The radiologist may be able to provide important prognostic information that allows clinicians to manage expectations and plan appropriately. Furthermore, some imaging studies will provide essential forensic information. Unfortunately, many cases of attempted suicide will end in brain death. The radiologist may have a role in these cases in identifying evidence of hypoxic-ischaemic brain injury, confirming a diagnosis of brain death through judicious use of ancillary tests and, finally, in donor screening for organ transplantation. A review is presented to illustrate the imaging features of self-harm, suicide, and brain death, and to highlight the important role of the radiologist in these cases.

Brain death in children: is computed tomography angiography reliable as an ancillary test?

BACKGROUND

The diagnosis of brain death is primarily clinical. Sometimes ancillary tests are needed.

OBJECTIVE

This study compared sensitivity and interobserver agreement of the 10-, 7- and 4-point CT angiography scoring systems for the diagnosis of brain death in children.

MATERIALS AND METHODS

CT angiography examinations of 50 pediatric patients with a clinical diagnosis of brain death were evaluated according to 10-, 7- and 4-point scoring systems. Images were evaluated by two radiologists who considered the vessel opacification first in the arterial phase (A₀-V₅₀) and then in the venous phase (A₀-V₅₀). We evaluated interobserver agreement for the assessment of vessel opacification and diagnosis of brain death. We compared the differences among brain death diagnoses between children with craniotomy-craniectomy defects, open fontanelles and preserved bone integrity. We subdivided children into two groups according to age: ≤ 2 years and > 2 years. We calculated sensitivities according to age groups.

RESULTS

Using the clinical exam as the reference standard, we found sensitivities for 10-, 7- and 4-point scoring systems to be 70%, 88% and 92% in the A₀-V₅₀ method and 40%, 82% and 82% in the A₅₀-V₅₀ method, respectively. Percentage agreement between readers was 78% for the 7-point scale using the A₀-V₅₀ method and more than 90% for other scoring systems for both the A₀-V₅₀ method and the A₅₀-V₅₀ method. The sensitivity was much lower in children with open anterior fontanelles compared to the groups with preserved bone integrity and with a craniotomy-craniectomy defect.

CONCLUSION

Just as in adult age groups, in children the 4-point scale appears to be more sensitive than the 10- and 7-point scales for CT angiography-based assessment of brain death. Because the scoring systems have similar sensitivities, they could be used as ancillary tests in pediatric cases.

Computed Tomography Angiography (CTA) in Selected Scenarios with Risk of Possible False-Positive or False-Negative Conclusions in Diagnosing Brain Death

It is widely accepted that brain death (BD) is a diagnosis based on clinical examination. However, false-positive and false-negative evaluation results may be serious limitations. Ancillary tests are used when there is uncertainty about the reliability of the neurologic examination. Computed tomography angiography (CTA) is an ancillary test that tends to have the lowest false-positive rates. However, there are various influencing factors that can have an unfavorable effect on the validity of the examination method. There are inconsistent protocols regarding the evaluation criteria such as scoring systems. Among the most widely used different scoring systems the 4-point CTA-scoring system has been accepted as the most reliable method. Appropriate timing and/or Doppler pre-testing could reduce the number of possible premature examinations and increase the sensitivity of CTA in diagnosing cerebral circulatory arrest (CCA). In some cases of inconclusive CTA, the whole brain computed tomography perfusion (CTP) could be a crucial adjunct. Due to the increasing significance of CTA/CTP in determining BD, the methodology (including benefits and limitations) should also be conveyed via innovative electronic training tools, such as the BRAINDEXweb teaching tool based on an expert system.

Cerebral blood vessels and perfusion in the pediatric brain death: five cases studied by neuroimaging

PURPOSE

To detect the cerebral blood vessels and perfusion using neuroimaging modalities including computed tomography angiography (CTA), computed tomography perfusion (CTP), and arterial spin labeling (ASL) in children with brain death (BD).

METHODS

According to the current children's BD criteria, 5 children (3 males, 2 females, mean age of 5.65 years) with BD were enrolled from January 2019 to December 2020. The imaging features of CTA, CTP, and ASL were evaluated to analyze the visualization of important intracranial blood vessels and the states of the cerebral blood flow (CBF) and cerebral blood volume (CBV) related to the region of interest (ROI) brain tissue during the two clinical assessments for BD.

RESULTS

The "4-point scale" scoring system of CTA was applied to evaluate BD and no negative results were detected. The CTP results of the 5 children suggested the cessation of cerebral circulation with 100% positive results. The ranges of CBF and CBV were 0.00-9.52 ml/100 g/min (mean value 4.95 ± 1.69 ml/100 g/min) and 0.00-1.34 ml/100 g (mean value 0.36 ± 0.20 ml/100 g), respectively. One patient also underwent ASL examination, which demonstrated a significant reduction in whole brain perfusion, indicating the absence of cerebral circulation. The CBF values of the brainstem, basal ganglia, and prefrontal lobe were 11.61 ± 1.49 ml/100 g/min, 7.81 ± 2.42 ml/100 g/min, and 9.94 ± 2.01 ml/100 g/min, respectively.

CONCLUSION

Neuroimaging examinations particularly CTA and CTP reveal well the hemodynamic and cerebral blood vessels changes of BD, which can be used as supplementary supportive evidence for the declaration of brain death in children.

Comparison of early- and late-phase CT angiography findings in brain death

BACKGROUND

Late-phase images on computed tomography angiography (CTA), traditionally used for assessing cerebral circulatory arrest in brain death, suffer from suboptimal diagnostic yield due to stasis filling. Herein, we assessed contrast filling in individual intracranial arteries and veins in the early and late phases of CTA in patients with clinically confirmed brain death.

METHODS

Contrast opacification within 28 arterial/venous segments was evaluated in both phases of CTA in 79 patients. This information was combined with reports in the literature to calculate prevalence of contrast filling in different intracranial vessels. Additionally, diagnostic sensitivity of 4-point, 7-point, and 10-point scores defined for brain death were compared among ratings based on early, late, and both phases (arteries rated on early, veins rated on late phase) of imaging.

RESULTS

The median (IQR) number of vessel segments with contrast opacification was 0 (0-2) in early phase and 6 (0-10) in late phase. All segments showed increased prevalence of opacification when evaluated in late phase (p < 0.05). The M4 segments of MCA, internal cerebral veins, and vein of Galen had the lowest percentage of opacification in both phases. The sensitivity of 4-, 7-, and 10-point scoring algorithms increased from 59-91% to 94-99% when ratings were performed using early-phase images rather than based solely on late-phase images.

CONCLUSIONS

The incorporation of early-phase images might be considered as a strategy to improve the sensitivity of CTA as an ancillary test in confirming brain death, especially in patients without missing or questionable elements in clinical examination.

Computed tomography angiography scoring systems and the role of skull defects in the confirmation of brain death

To assess and compare all current computed tomography angiography (CTA) scoring systems for the diagnostic workup of brain death (BD) to digital subtraction angiography (DSA) and clinical tests. Fifty-two patients with a clinical suspicion of BD underwent CTA and subsequently DSA. The diagnostic performance of all current CTA scoring systems was compared to that of DSA, in all patients with a suspicion of BD. A comparison to clinical tests was made only in DSA-positive for BD patients (n = 49), since in DSA-negative BD patients (n = 3) clinical tests were not performed. Further subgroup analysis was performed in relation to skull defects (SDs) stratification. Statistical analysis was conducted by applying statistics-contingency tables, Cochran's-Q test and McNemar's test. The CTA -10, and -7- and all 4-point scoring systems, showed overall sensitivities of 81,6%, 87.8% and 95.9% respectively and 100% specificity, when compared to DSA. In patients with a clinical verification of BD, the CTA -10 and -7-point scoring systems were significantly inferior to clinical tests (p = 0.004 and p = 0.031), while the 4-point scoring systems showed no such difference (p = 0.5). All 4-point scoring systems showed 100% sensitivity in patients with a minor SD or no SD. In patients with a major SD, all CTA scoring systems (- 10, - 7- and all 4-point) were less sensitive (62.5%, 62.5% and 75% respectively). The presence of a major SD was associated with an 8 × relative risk for false negative results in all 4-point scoring systems. CTA showed excellent diagnostic performance in patients with a suspicion of BD. The 4-point CTA scoring systems are the most sensitive for the diagnosis of BD, although in patients with a major SD patient, the role of CTA is ambiguous.

Reliability of CT angiography scoring systems used for brain death and the effect of cranial interventions on the results

OBJECTIVE

To assess vascular opacifications, the efficiency, and interobserver agreement (IOA) of five different computed tomography angiography (CTA) brain death (BD) scoring systems in patients with and without cranial interventions, for determining alternative findings correctly supporting BD diagnosis by CTA even in cranial intervention presence.

METHODS

45 patients clinically identified with BD and evaluated with CTA were included. IOA of five different scoring systems used for CTA BD diagnosis, the effect of intracranial interventions on scoring systems, and vascular opacification were evaluated.

RESULTS

IOA was almost perfect (κ = 0.843-0.911, p < 0.05) and substantial (κ = 0.771-0.776, p < 0.05) in all scoring systems. Significant relationships were observed between craniectomy presence and middle cerebral artery M4 segment and internal cerebral vein (ICV) opacification. No opacification was observed in straight sinus (SS) by observers in any of the craniectomized patients.

CONCLUSION

IOA of CTA scoring systems is adequate. But a significant degree of false-negative results is observed due to ICV filling in craniectomy cases. Opacification presence in SS can give an idea of BD in these cases.

Assessment of Cerebral Circulatory Arrest via CT Angiography and CT Perfusion in Brain Death Confirmation

Objective

To compare the utility of computed tomography perfusion (CTP) and three different 4-point scoring systems in computed tomography angiography (CTA) in confirming brain death (BD) in patients with and without skull defects.

Materials and Methods

Ninety-two patients clinically diagnosed as BD using CTA and/or CTP for confirmation were retrospectively reviewed. For the final analysis, 86 patients were included in this study. Images were re-evaluated by three radiologists according to the 4-point scoring systems that consider the vessel opacification on 1) the venous phase for both M4 segments of the middle cerebral arteries (MCAs-M4) and internal cerebral veins (ICVs) (A60-V60), 2) the arterial phase for the MCA-M4 and venous phase for the ICVs (A20-V60), 3) the venous phase for the ICVs and superior petrosal veins (ICV-SPV). The CTP images were independently reviewed. The presence of an open skull defect and stasis filling was noted.

Results

Sensitivities of the ICV-SPV, A20-V60, A60-V60 scoring systems, and CTP in the diagnosis of BD were 89.5%, 82.6%, 67.4%, and 93.3%, respectively. The sensitivity of A20-V60 scoring was higher than that of A60-V60 in BD patients (p < 0.001). CTP was found to be the most sensitive method (86.5%) in patients with open skull defect (p = 0.019). Interobserver agreement was excellent in the diagnosis of BD, in assessing A20-V60, A60-V60, ICV-SPV, CTP, and good in stasis filling (κ: 0.84, 0.83, 0.83, 0.83, and 0.67, respectively).

Conclusion

The sensitivity of CTA confirming brain death differs between various proposed 4-point scoring systems. Although the ICV-SPV is the most sensitive, evaluation of the SPV is challenging. Adding CTP to the routine BD CTA protocol, especially in cases with open skull defect, could increase sensitivity as a useful adjunct.