Hemosiderin Detected by T2*-Weighted Magnetic Resonance Imaging in Patients With Unruptured Cerebral Aneurysms: Indication of Previous Bleeding?

Abstract

Previous bleeding from a cerebral aneurysm indicates a higher risk of rupture. Hemosiderin may be detected during aneurysm surgery or by preoperative imaging sensitive to hemosiderin. The detection of hemosiderin deposits by T 2 * -weighted magnetic resonance (MR) imaging was evaluated in 49 patients with unruptured cerebral aneurysms who underwent open surgery. MR imaging was performed using 3.0 tesla MR scanner. Two sequences of T 2 *-weighted imaging, and proton density images were obtained. Preliminary study in patients with old subarachnoid hemorrhage provided the definitions of likely pathological findings during surgery and on T 2 * -weighted imaging due to previous hemorrhage. Hemosiderin deposits in the subarachnoid space were observed during surgery in 9 of the 49 patients, although no obvious rupture site was detected around the aneurysm wall. Size, presence of bleb, location, and number of aneurysms showed no significant difference between patients with and without hemosiderin deposition. Hypointense areas on T 2 *-weighted imaging were recognized in four patients. The mean size of the aneurysms in these patients was 9.8 mm, significantly larger than those in other patients (p ＝ 0.029). Hemosiderin deposits were observed during surgery in sites close to the lesions on T 2 *-weighted imaging in two of these four patients. Hemosiderin deposits are not rare in patients with unruptured aneurysms, and preoperative T 2 *-weighted imaging can detect such deposits.

Longitudinal profile of iron accumulation in good‐grade subarachnoid hemorrhage

“…These researchers reported a high predictive value of the T2*‐weighted signal to detect the location of the initial hemorrhage, however low specificity, suggesting diffusion of blood products within the subarachnoid space over time. Histological examination of patients with incidentally detected unruptured intracranial aneurysms showed that hemosiderin was stored in the arachnoid tissue and granulations, indicating this iron‐storage complex to be resistant to washout through cerebrospinal fluid 31, 32. We are not aware of any studies focusing on whole brain analysis of iron depositions within the brain tissue following SAH using either iron‐sensitive MRI sequences or postmortem histological investigations.…”

Occult hemorrhage in children with severe ITP

“…However, a particularly novel finding in this investigation was that CNS microbleeding is a potential risk in this patient population. While brain microbleeds have been studied in adults with hypertension and previous stroke as prognostic markers of future brain hemorrhage [12][13][14][15], to our knowledge no prior studies have evaluated brain microbleeds in children. The reported prevalence of brain microbleeds in healthy adults is 5% and increases with age, with 34% related to ischemic events and 60% associated with hemorrhage [16].…”

“…Such "brain microbleeds" appear dark on T2-weighted spin-echo sequences, appearing enhanced when relying on gradient-echo sequence [12,13]. Studies in adults with unruptured cerebral aneurysms or hypertension have shown that brain microbleeds can be detected as early as 3 weeks and for as long as 18 months after the onset of localized hemosiderin deposition [12,14,15]. Based on prior imaging reports in the literature [12][13][14][15] that describe adults, MR imaging for this study was performed with a 3-T FFE scanner.…”

“…Studies in adults with unruptured cerebral aneurysms or hypertension have shown that brain microbleeds can be detected as early as 3 weeks and for as long as 18 months after the onset of localized hemosiderin deposition [12,14,15]. Based on prior imaging reports in the literature [12][13][14][15] that describe adults, MR imaging for this study was performed with a 3-T FFE scanner. We obtained noncontrast, T2 gradient echo sequence susceptibility weighted images in the axial plane 3 months after the initial diagnosis or relapse of ITP.…”

Communication of medical images to diverse audiences using multimodal imaging

“…In vivo MRI studies have shown that hemosiderin deposits can be visualised via T2-weighted imaging in patients with un-ruptured aneurysms [11]. Considering this, the model system chosen for study was the pharmacodynamic action of the vascular disrupting agent combretastatin A-4 phosphate (CA4P) on a mouse fibrosarcoma model.…”