CTP for the Screening of Vasospasm and Delayed Cerebral Ischemia in Aneurysmal SAH: A Systematic Review and Meta-analysis.

BACKGROUND: Delayed cerebral ischemia and vasospasm are the most common causes of late morbidity following aneurysmal SAH, but their diagnosis remains challenging. PURPOSE: This systematic review and meta-analysis investigated the diagnostic performance of CTP for detection of delayed cerebral ischemia and vasospasm in the setting of aneurysmal SAH. DATA SOURCES: Studies evaluating the diagnostic performance of CTP in the setting of aneurysmal SAH were searched on the Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Cochrane Clinical Answers, Cochrane Methodology Register, Ovid MEDLINE, EMBASE, American College of Physicians Journal Club, Database of Abstracts of Reviews of Effects, Health Technology Assessment, National Health Service Economic Evaluation Database, PubMed, and Google Scholar from their inception to September 2023. STUDY SELECTION: Thirty studies were included, encompassing 1786 patients with aneurysmal SAH and 2302 CTP studies. Studies were included if they compared the diagnostic accuracy of CTP with a reference standard (clinical or radiologic delayed cerebral ischemia, angiographic spasm) for the detection of delayed cerebral ischemia or vasospasm in patients with aneurysmal SAH. The primary outcome was accuracy for the detection of delayed cerebral ischemia or vasospasm. DATA ANALYSIS: Bivariate random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio. Subgroup analyses for individual CTP parameters and early-versus-late study timing were performed. Bias and applicability were assessed using the modified QUADAS-2 tool. DATA SYNTHESIS: For assessment of delayed cerebral ischemia, CTP demonstrated a pooled sensitivity of 82.1% (95% CI, 74.5%-87.8%), specificity of 79.6% (95% CI, 73.0%-84.9%), positive likelihood ratio of 4.01 (95% CI, 2.94-5.47), and negative likelihood ratio of 0.23 (95% CI, 0.12-0.33). For assessment of vasospasm, CTP showed a pooled sensitivity of 85.6% (95% CI, 74.2%-92.5%), specificity of 87.9% (95% CI, 79.2%-93.3%), positive likelihood ratio of 7.10 (95% CI, 3.87-13.04), and negative likelihood ratio of 0.16 (95% CI, 0.09-0.31). LIMITATIONS: QUADAS-2 assessment identified 12 articles with low risk, 11 with moderate risk, and 7 with a high risk of bias. CONCLUSIONS: For delayed cerebral ischemia, CTP had a sensitivity of >80%, specificity of >75%, and a low negative likelihood ratio of 0.23. CTP had better performance for the detection of vasospasm, with sensitivity and specificity of >85% and a low negative likelihood ratio of 0.16. Although the accuracy offers the potential for CTP to be used in limited clinical contexts, standardization of CTP techniques and high-quality randomized trials evaluating its impact are required.

Noncontrast MRI for Hepatocellular Carcinoma Detection: A Systematic Review and Meta-analysis - A Potential Surveillance Tool?

BACKGROUND AND AIMS: This meta-analysis investigates the diagnostic performance of non-contrast magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC). METHODS: A systematic review was performed to May 2020 for studies which examined the diagnostic performance of non-contrast MRI (multi-sequence or diffusion-weighted imaging (DWI)- alone) for HCC detection in high risk patients. The primary outcome was accuracy for the detection of HCC. Random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio (LR) and negative LR. Subgroup analyses for cirrhosis and size of the lesion were performed. RESULTS: Twenty-two studies were included involving 1685 patients for per-patient analysis and 2128 lesions for per-lesion analysis. Multi-sequence non-contrast MRI (NC-MRI) using T2+DWI±T1 sequences had a pooled per-patient sensitivity of 86.8% (95%CI:83.9-89.4%), specificity of 90.3% (95%CI:87.3-92.7%), and negative LR of 0.17 (95%CI:0.14-0.20). DWI-only MRI (DW-MRI) had a pooled sensitivity of 79.2% (95%CI:71.8-85.4%), specificity of 96.5% (95%CI:94.3-98.1%) and negative LR of 0.24 (95%CI:1.62-0.34). In patients with cirrhosis, NC-MRI had a pooled per-patient sensitivity of 87.3% (95%CI:82.7-91.0%) and specificity of 81.6% (95%CI:75.3-86.8%), whilst DWI-MRI had a pooled sensitivity of 71.4% (95%CI:60.5-80.8%) and specificity of 97.1% (95%CI:91.9-99.4%). For lesions <2 cm, the pooled per-lesion sensitivity was 77.1% (95%CI:73.8-80.2%). For lesions >2 cm, pooled per-lesion sensitivity was 88.5% (95%CI:85.0-91.5%). CONCLUSION: Non-contrast MRI has a moderate negative LR and high specificity with acceptable sensitivity for the detection of HCC, even in patients with cirrhosis and with lesions <2 cm. Prospective trials to validate if non-contrast MRI can be used for HCC surveillance is warranted.

The organization of spinal motor neurons in a monotreme is consistent with a six-region schema of the mammalian spinal cord.

The motor neurons in the spinal cord of an echidna (Tachyglossus aculeatus) have been mapped in Nissl-stained sections from spinal cord segments defined by spinal nerve anatomy. A medial motor column of motor neurons is found at all spinal cord levels, and a hypaxial column is found at most levels. The organization of the motor neuron clusters in the lateral motor column of the brachial (C5 to T3) and crural (L2 to S3) limb enlargements is very similar to the pattern previously revealed by retrograde tracing in placental mammals, and the motor neuron clusters have been tentatively identified according to the muscle groups they are likely to supply. The region separating the two limb enlargements (T4 to L1) contains preganglionic motor neurons that appear to represent the spinal sympathetic outflow. Immediately caudal to the crural limb enlargement is a short column of preganglionic motor neurons (S3 to S4), which it is believed represents the pelvic parasympathetic outflow. The rostral and caudal ends of the spinal cord contain neither a lateral motor column nor a preganglionic column. Branchial motor neurons (which are believed to supply the sternomastoid and trapezius muscles) are present at the lateral margin of the ventral horn in rostral cervical segments (C2-C4). These same segments contain the phrenic nucleus, which belongs to the hypaxial column. The presence or absence of the main spinal motor neuron columns in the different regions echidna spinal cord (and also in that of other amniote vertebrates) provides a basis for dividing the spinal cord into six main regions - prebrachial, brachial, postbrachial, crural, postcrural and caudal. The considerable biological and functional significance of this subdivision pattern is supported by recent studies on spinal cord hox gene expression in chicks and mice. On the other hand, the familiar 'segments' of the spinal cord are defined only by the anatomy of adjacent vertebrae, and are not demarcated by intrinsic gene expression. The recognition of segments defined by vertebrae (somites) is obviously of great value in defining topography, but the emphasis on such segments obscures the underlying evolutionary reality of a spinal cord comprised of six genetically defined regions. The six-region system can be usefully applied to the spinal cord of any amniote (and probably most anurans), independent of the number of vertebral segments in each part of the spinal column.