Watson CG, Dehaes M, Gagoski BA, Grant PE, Rivkin MJ. Arterial Spin Labeling Perfusion Magnetic Resonance Imaging Performed in Acute Perinatal Stroke Reveals Hyperperfusion Associated With Ischemic Injury. Stroke. 2016
Eighty-seven consecutive patients with acute borderzone strokes were identified, 62 with CBZ and 55 with IBZ. Thirty of all included stroke patients were considered FLAIR-positive. The authors found that FLAIR vascular hyperintensities were associated with a more severe clinical presentation and a poorer clinical prognosis in patients with CBZ strokes, but not in patients with IBZ strokes. They concluded the presence of FLAIR vascular hyperintensities, “may help to identify CBZ-infarcted patients who require close observation and hemodynamic control.”
The lacune, often used interchangeably with the definition of a stroke of small vessel atherosclerotic etiology, is traditionally based on a size definition of no greater than 15 mm. It is a classic feature of cerebral small vessel disease. However, despite its prolific use in the stroke literature, the exact characteristics and morphological features of a lacune are not well defined. Here, the authors analyzed the shape of incident lacunes in CADASIL, a genetically inherited small vessel arteriopathy, to better define the lacune’s morphological features.
Collateral Circulation Status as Assessed by MR-Perfusion Modulates Relationship Between Time and Development of FLAIR Signal
Fluid-Attenuated Inversion Recovery eral Circulation. Stroke. 2016
The authors utilized clinical and neuroimaging data from the AXIS 2 trial, a multicenter Phase IIb placebo-controlled, randomized and double blinded trial investigating recombinant Granulocyte Colony Stimulating Factor in acute stroke. A total of 141 patients were included for analysis, excluding patients with incomplete imaging sequences, severe FLAIR lesions overlapping the acute lesion or in the contralateral hemisphere (as the contralateral hemisphere was used for FLAIR intensity measurement), or reperfused core. Quantitative relative FLAIR maps (rFLAIR) were calculated in a voxel-based manner using in house software. Collateral status assessed by HIR was dichotomized into “good” (n= 87, 61.7%) and “poor” (n= 54, 38.3%). Patients with poor collaterals had more severe stroke symptoms at baseline (NIHSS 14 vs NIHSS 11, p= 0.01), larger DWI lesion volumes (47.2 mL vs 14.6 mL, p= <0.01), and larger TMax > 6s perfusion volumes (91.5 mL vs 45.8 mL, p=0.01).
Orito K, Hirohata M, Nakamura Y, Takeshige N, Aoki T, Hattori G, et al. Leakage Sign for Primary Intracerebral Hemorrhage: A Novel Predictor of Hematoma Growth. Stroke. 2016
Intracerebral hemorrhage (ICH) is a devastating disease with a one-month mortality of 40%. Although initial ICH volume is the strongest predictor of mortality, hematoma expansion is a potentially modifiable risk factor that correlates well with both functional outcome and death and occurs in up to 40% of patients with ICH. Research has therefore been focused on methods to 1) identify patients at risk of hematoma expansion and 2) reduce hematoma expansion.
The “spot sign” has been previously correlated with both hematoma expansion and poor functional outcome; however, the spot sign is not a perfect predictor of hematoma expansion. Although the specificity of the spot sign is high, the sensitivity is only around 50%. In this study, Drs. Orito and Morioka et al evaluate a new predictor for hematoma expansion in ICH: the “leakage sign.”
The authors evaluate 80 patients with a primary ICH who underwent a CTA and a second CT (delayed phase image) 5 minutes later. The leakage sign was determined by comparing the arterial and delayed phase CT images. Each neuroradiologist measured a region of interest (ROI) of 1-cm diameter on the delayed phase images. This region was considered the highest change in Hounsfield Units between the delayed and arterial phase images and represented the leakage of contrast medium into the hematoma. The same ROI circle was then drawn on the arterial phase CT image and the Hounsfield Units were measured. A change >10% in Hounsfield Units was considered a positive leakage sign, or hematoma expansion. A follow-up CT was performed 24 hours later where hematoma expansion was defined as >10% change in hematoma volume from the initial CT.
The authors found that the spot sign was positive in 18 (22%) of patients and that the leakage sign was positive in 35 (43%) of patients. 33 of the 35 patients with a positive leakage sign also had positive spot signs. Overall, leakage sign had a higher sensitivity and specificity than the spot sign: 93.3% and 88.9%, respectively, versus 77.8% and 73.8%. In addition, the leakage sign proved to be a better predictor of outcomes than the spot sign. Patients with a positive leakage sign had significantly poorer outcomes (20.0% versus 51.5%), but outcomes were unaffected in patients with a positive spot sign.
In conclusion, the leakage sign appears to be both an easy and reliable method to predict hematoma expansion in patients with ICH.
Ischemic stroke presentations can vary significantly and some presentations are more likely to be overlooked or thought to be stroke mimics. Additionally, some patient populations (such as young patients, women, and minorities) are more likely to be attributed nonstroke etiologies. The danger is, of course, missed treatment opportunities. However, patients with missed strokes are also less likely to receive appropriate monitoring for neurological progression or stroke-related complications.
Peggy Nguyen, MD
Goyal MS, Hoff BG, Williams J, Khoury N, Wiesehan R, Heitsch L, et al. Streamlined Hyperacute Magnetic Resonance Imaging Protocol Identifies Tissue-Type Plasminogen Activator–Eligible Stroke Patients When Clinical Impression Is Stroke Mimic. Stroke. 2016
Despite advances in imaging, the radiologic component of the tPA decision-making is predicated on a non-contrast CT head, guided by the clinical history and exam. Sometimes, however, the clinical exam or history can be confusing and the CT scan does not provide much additional diagnostic data; stroke mimics make up anywhere between 1-16% of the patients presenting with stroke-like symptoms at large institutions. The use of a hyperacute MRI (hMRI) can help differentiate strokes from stroke mimics, and potentially minimize tPA given to mimics and, perhaps more importantly, ensure that tPA is not withheld from patients who are suspected to be mimics, but are actually strokes.
Here, the authors report an institution-specific streamlined hMRI protocol in the setting of acute stroke. The hMRI protocol described here provides DWI/ADC, FLAIR, and T2*GRE sequences in just under 6 minutes. In order to avoid overutilization, physicians were instructed to order the hMRI only when the initial diagnostic impression was likely stroke mimic, but ischemic stroke could not be entirely ruled out and, if MRI was not available at their institution, the physician would not give the patient tPA. 57 patients, identified as stroke mimics, underwent the hMRI protocol, with 11 having the final diagnosis of stroke, 4 with the final diagnosis of TIA, and the remaining diagnoses being conversion disorder, seizure, complicated migraine, and other. Seven of the 11 stroke patients received IV tPA. There were no differences in door-to-needle, onset-to-needle, or door-to-arrival times for all IV tPA treated patients pre- and post-hMRI; however, the door-to-needle time for tPA treated patients screened with CT alone were significantly shorter than the 7 tPA patients screened with hMRI (37 minutes vs 112 minutes).
Although the overall metrics (door to needle, onset to needle, etc) did not change much with the institution of hMRI protocol, likely due to the minority of patients who went on to receive tPA under the protocol, using the hMRI protocol did lead to substantially longer door-to-needle times for patients who received tPA. However, longer door-to-needle times are preferable than withholding tPA, and it is probable that these patients, having been initially identified as stroke mimics, would not have received tPA otherwise. The use of a hMRI does have its limitations, given it is not widely available and many institutions may not have the resources to staff it emergently, but in institutions where the resources are available, it could potentially increase tPA usage to patients with strokes and decrease tPA usage to patients without strokes.
Exposures, Outcomes, and Covariates
Meta-Analysis Concludes Utility of CTA Spot Sign is Dependent Upon Timing and is Not Sufficient to Predict Hematoma Expansion in Acute ICH
Dowlatshahi D, Brouwers HB, Demchuk AM, Hill MD, Aviv RI, Ufholz L-A, et al. Predicting Intracerebral Hemorrhage Growth With the Spot Sign: The Effect of Onset-to-Scan Time. Stroke. 2016
Intracerebral hemorrhage (ICH) causes a significant amount of stroke-related morbidity and mortality. Of the various prognostic factors in ICH, hematoma expansion is one of the few potentially modifiable ones and as such has been a topic of increasing research. Unfortunately, large-scale randomized controlled trials aimed at preventing hematoma expansion have not shown robust results, possibly owing to the limited ability of clinicians to predict which patients are at greatest risk. One of the more promising diagnostic features in identifying such patients is the “spot sign” of contrast extravasation in the hematoma bed of ICH patients undergoing CT angiography (CTA). However, the predictive value of the spot sign has differed widely across studies, which may reflect variability in delay between ictus and CTA acquisition. Dowlatshahi et al. sought to examine the predictive value of the spot sign in relationship to onset-to-CTA times in patients with acute ICH by conducting a systematic review and patient-level meta-analysis.