Gradient echo MRI: implementation of a training tutorial for intracranial hemorrhage diagnosis

Current approaches and advances in the imaging of stroke

A stroke occurs when the blood flow to the brain is suddenly interrupted, depriving brain cells of oxygen and glucose and leading to further cell death. Neuroimaging techniques, such as computed tomography and magnetic resonance imaging, have greatly improved our ability to visualise brain structures and are routinely used to diagnose the affected vascular region of a stroke patient's brain and to inform decisions about clinical care. Currently, these multimodal imaging techniques are the backbone of the clinical management of stroke patients and have immensely improved our ability to visualise brain structures. Here, we review recent developments in the field of neuroimaging and discuss how different imaging techniques are used in the diagnosis, prognosis and treatment of stroke.

Summary: Stroke imaging has undergone seismic shifts in the past decade. Although magnetic resonance imaging (MRI) is superior to computed tomography in providing vital information, further research on MRI is still required to bring its full potential into clinical practice.

Differentiation of hemorrhagic infarction from primary intracerebral hemorrhage in the chronic period

Regarding incidentally found old hemorrhagic foci on gradient-echo magnetic resonance imaging (GRE), it is difficult to distinguish whether the foci are the consequence of hemorrhagic infarction (HI) or primary intracerebral hemorrhage (PICH). We analyzed the radiological characteristics of patients with a definite history of HI or PICH by reviewing long-term follow-up GRE. We retrospectively enrolled patients with HI or PICH, verified by clinical history and radiological findings, who had undergone follow-up GRE at least 3 months after the first imaging. The shape of the hemorrhagic lesion was classified as "cavitation" or "no cavitation." The shape of the hemosiderin rim was classified as total dark rim and partial dark rim. Hyperintense perilesional signal was determined when an obvious hyperintensity on T2-weighted image was present. Further, we compared the radiological characteristics between HI and PICH. In total, 69 patients (38 with HI and 31 with PICH) were enrolled, of whom 45 (65%) were men. The mean patient age was 65.5 ± 12.7 years. The mean time interval from the initial stroke onset to the follow-up image was 56.2 months. Hyperintense perilesional signal was observed in 38 patients; it was associated with HI (33/38 vs. 5/31, p < 0.001). Furthermore, partial dark rim was associated with HI (34/40 vs. 4/29, p < 0.001). Cavitation was more frequently observed in patients with HI than in those with PICH (36/60 vs. 2/9, p = 0.068). Presence of hyperintense perilesional signal and partially encasing dark hemosiderin rim suggest that chronic hemorrhagic foci are the sequelae of HI, not PICH.

QuickBrain MRI for the detection of acute pediatric traumatic brain injury

OBJECTIVE The current gold-standard imaging modality for pediatric traumatic brain injury (TBI) is CT, but it confers risks associated with ionizing radiation. QuickBrain MRI (qbMRI) is a rapid brain MRI protocol that has been studied in the setting of hydrocephalus, but its ability to detect traumatic injuries is unknown. METHODS The authors performed a retrospective cohort study of pediatric patients with TBI who were undergoing evaluation at a single Level I trauma center between February 2010 and December 2013. Patients who underwent CT imaging of the head and qbMRI during their acute hospitalization were included. Images were reviewed independently by 2 neuroradiology fellows blinded to patient identifiers. Image review consisted of identifying traumatic mass lesions and their intracranial compartment and the presence or absence of midline shift. CT imaging was used as the reference against which qbMRI was measured. RESULTS A total of 54 patients met the inclusion criteria; the median patient age was 3.24 years, 65% were male, and 74% were noted to have a Glasgow Coma Scale score of 14 or greater. The sensitivity and specificity of qbMRI to detect any lesion were 85% (95% CI 73%-93%) and 100% (95% CI 61%-100%), respectively; the sensitivity increased to 100% (95% CI 89%-100%) for clinically important TBIs as previously defined. The mean interval between CT and qbMRI was 27.5 hours, and approximately half of the images were obtained within 12 hours. CONCLUSIONS In this retrospective pilot study, qbMRI demonstrated reasonable sensitivity and specificity for detecting a lesion or injury seen with neuroimaging (radiographic TBI) and clinically important acute pediatric TBI.

Diagnosis of intracranial hemorrhagic lesions: comparison between 3D-SWAN (3D T2*-weighted imaging with multi-echo acquisition) and 2D-T2*-weighted imaging

BACKGROUND

3D-susceptibility-weighted angiography (SWAN) can produce high-resolution images that yield excellent susceptibility-weighted contrast at a relatively short acquisition time.

PURPOSE

To compare SWAN- and 2D-T2*-weighted gradient-echo images (T2*-WI) for their sensitivity in the depiction of cerebral hemorrhagic lesions.

MATERIAL AND METHODS

We subjected 75 patients with suspected cerebral hemorrhagic lesions to SWAN and T2*-WI at 3T. We first measured the contrast-to-noise ratio (CNR) using an agar phantom that contained different concentrations of superparamagnetic iron oxide (SPIO). The acquisition time for SWAN and T2*-WI was similar (182 vs. 196 s). Neuroradiologists compared the two imaging methods for lesion detectability and conspicuity.

RESULTS

The CNR of the phantom was higher on SWAN images. Of the 75 patients, 50 were found to have a total of 278 cerebral hemorrhagic lesions (microbleeds, n = 229 [82.4%]; intracerebral hemorrhage, n = 18 [6.5%]; superficial siderosis, n = 13 [4.7%]; axonal injuries, n = 8 [2.9%]; subarachnoid hemorrhage [SAH] or brain contusion, n = 3 each [1.0%]; subdural hematoma, n = 2 [0.7%]; cavernous hemangioma or dural arterteriovenous fistula, n = 1 each [0.4%]). In none of the lesions was the SWAN sequence inferior to T2*-WI with respect to lesion detectability and conspicuity. In fact, SWAN yielded better lesion conspicuity in patients with superficial siderosis and SAH: it detected significantly more lesions than T2*-WI (P < 0.01) and it was particularly useful for the detection of microbleeds and lesions near the skull base.

CONCLUSION

SWAN is equal or superior to standard T2*-WI for the diagnosis of various cerebral hemorrhagic lesions. Because its acquisition time is reasonable it may replace T2*-WI.

Varying clinical presentations of familial cerebral cavernous malformations (CCMs) and spinal cord cavernous malformations (SCCMs)

We present a family afflicted by both extensive cerebral cavernous malformations (CCMs) and spinal cord cavernous malformations (SCCMs). These may be inherited in an autosomal dominant pattern or occur sporadically. The presentation varies and may include a multitude of clinical symptoms separated in time and space. Cavernous malformations should be considered in the differential diagnosis of such entities as stroke, headache, multiple sclerosis, and new-onset seizures after an intraparenchymal hemorrhage.