Radiologists, technologists, translational researchers, and healthcare providers caring for neurological ICU patients.Attendees of this session will gain insight into the importance of identifying location, source and timing of intracranial hemorrhage through a case-based format, and better appreciate how the interplay of these factors can affect subsequent image interpretation and clinical decision-making, including in the setting of traumatic brain injury (TBI) and vasospasm (VSP).

ICH is a medical emergency that requires rapid diagnosis and appropriate triage and management of patients. Greater than 20% of patients will exhibit a drop in Glasgow Coma Scale (GCS) score of 2 points or more from the time of initial emergency medical services assessment to the time that they are evaluated upon arrival in the hospital [1]. Another 15-23% of patients will experience further deterioration within the first hours following arrival to the hospital [2,3].

In the context of TBI, it is estimated that greater than 1.7 million persons in the United States will sustain TBI each year [4]. Of the survivors, 80,000 – 90,000 are left with debilitating long-term motor and cognitive disabilities [5].

Finally, VSP is a significant cause of death in neuro-intensive care units, in which an estimated 15–36% of patients with aneurysmal subarachnoid hemorrhage (aSAH) will suffer from cerebral infarction and associated neurological deficits [6-8], with death secondary to delayed cerebral ischemia (DCI) occurring in 7–23% of patients [9,10]. An additional 46% of survivors report long-term cognitive impairment affecting functional status and quality of life. These observations underscore the importance of early detection of VSP in patients at risk of developing significant DCI, since treatment of VSP is thought to prevent DCI development.

In these contexts, MR, including advanced MR techniques, can potentially better evaluate the physiological parameters of tissue injury and provide additional diagnostic information, not otherwise available via conventional, morphological imaging alone. We will thus examine the role that various advanced MR techniques might play in the context of evaluation of acute and subacute ICH.

An overview of the pertinent literature describing various diffusion techniques, as applied to ICH, will be performed with a primary focus on TBI and VSP. Standard diffusion tensor imaging (DTI), functional MRI and MR spectroscopy will be cursorily reviewed, including evaluation of commonly-derived descriptive scalar metrics, and associated post-processing methods. Additionally, SWI and ASL techniques will be discussed in the context of ICH and specifically TBI.

With respect to the detection of VSP in specific arterial territories in patients with aSAH, preliminary data In a small, prospective cohort, performed using a multi-delay ASL (MD-ASL) technique [11], will be presented and reviewed [12].

Studies evaluating mild TBI with DTI have demonstrated significant associations between aberrant white matter anisotropy and various functional outcome measures [13-16]. In addition, several preliminary studies suggest that ASL may play a notable role in the continued evaluation of mTBI; the ability to identify regional perfusion abnormalities and the opportunity to perform serial measurements interrogating intra- and inter-subject CBF (some within the same imaging session) make ASL an attractive imaging technique.

In evaluating VSP, a combined 47 vascular territories in ten consecutive patients were studied, in which ASL perfusion deficits were significantly associated with vasospasm on digital subtraction angiography (DSA) (p=0.002) [12]. Blinded two-reader neurointerventional assessment of ASL images suggested that evaluation of ASL-derived CBF would have prevented 3 of 10 patients from undergoing an unnecessary DSA, and readers agreed on modification to treatment recommendations in 60% of cases [12].

Advanced imaging methodologies hold promise in improving the sensitivity and detectability of associated imaging biomarkers that might better correlate with patient outcome and prognostication, allowing for improved triage and therapeutic guidance in the setting of TBI. In patients suspected of VSP following aSAH, obtaining MD-ASL prior to DSA may alter treatment and reduce the unnecessary use of hospital resources.

1. Advanced MR imaging techniques such as DTI, MR spectroscopy and functional MRI have made noteworthy contributions to recent research in various forms of TBI, and appear optimal for evaluating mTBI, based on their potential for prognostication and strong correlation with subject symptoms.

2. Perfusion information obtained from multi-delay multi-parametric ASL prior to DSA may reduce unnecessary DSA in select patients and modify therapy in others, possibly improving patient triage and management.