A chronic encapsulated intracerebral hematoma mimicking a brain tumor: Findings on arterial spin labeling of MRI

Abstract

Background

Intracerebral hematoma usually resolves spontaneously. Chronic encapsulated intracerebral hematoma is rare and mimics a brain tumor.

Case description

A 50-year-old man had developed intracerebral hematoma in the right temporal lobe. Computed tomography (CT) showed the gradually decreasing density of the hematoma. However, the hematoma did not decrease in size and it showed ring enhancement on contrast-enhanced CT for more than 1 year. Magnetic resonance imaging (MRI) revealed a lesion content showing a high intensity on both T1- and T2-weighted images with ring enhancement. The lesion was diagnosed as a chronic encapsulated intracerebral hematoma developing from an acute hematoma. Arterial spin labeling of MRI showed decreased blood perfusion even in the enhanced capsule, being different from findings of a cystic brain tumor.

Conclusion

Arterial spin labeling might be a useful modality to distinguish a chronic encapsulated intracerebral hematoma from a cystic hypervascular brain tumor.

Introduction

Intracerebral hematoma usually resolves spontaneously.¹ On rare occasions, it develops a mass after a period of time, and causes neurological deficits.² Several reports describing chronic encapsulated intracerebral hematoma (CEIH) have been published.^3–6 Radiological findings of CEIH are similar to those of brain tumors and it is sometimes misdiagnosed as a cystic brain tumor.⁷ We present a case of CEIH which resembled a cystic brain tumor. In our case, serial radiological examinations were performed from acute to chronic stages. We discuss the radiological characteristics of this rare condition, focusing on the differential diagnosis based on the findings of arterial spin labeling (ASL) of magnetic resonance imaging (MRI).

Methods

All MR examinations were performed using a 3 T MR scanner (Discovery MR750W, GE HealthCare, Milwaukee, WI) and 19 channel GEM Head Neck Unit (GE HealthCare). ASL images were obtained by three-dimensional single-shot fast spin-echo with in-plane spiral readout (3D FSE spiral). Scan parameters for ASL were: repetition time (TR)/echo time (TE), 4554 ms/10.7 ms; bandwidth, 62.5 kHz; slice thickness, 4.0 mm; matrix, 128 × 128; number of excitations (NEX), 2; field of vision (FOV), 24 × 24 cm²; number of scan locations: 30; post labeling delay, 1525 m; number of arms, 4; and scan time, 1 min 44 s.

Case report

A 50-year-old man experienced headache and vomiting, and he was admitted to another hospital. Computed tomography (CT) showed hemorrhage in the right temporal lobe. He was admitted and treated conservatively. Angiography and MRI revealed no vascular anomalies. He was discharged without neurological deficit about a month later. He was referred to a local neurosurgical clinic for follow-up examinations. CT showed gradual absorption of the hematoma (Figure 1(a)). However, CT obtained 3 months after onset still showed a mass with surrounding edema. From the radiological findings, the existence of a brain tumor or angioma was suspected, and he was referred to our department for further examinations. Contrast-enhanced (CE) CT in the third month showed ring enhancement of the lesion, mimicking a cystic brain tumor (Figure 1(b)).

Figure 1.

(a) CT obtained 1 month after onset showing a high-density lesion with perifocal edema in the left temporal lobe. (b) CE-CT in the third month showing ring enhancement of the mass. (c) CT in the 10th month showing a slight decrease of the lesion size and improving perifocal edema.

MRI indicated that the lesion was composed of a high-intensity content and low-intensity rim on both T1- and T2-weighted images (Figure 2(a) and (b)). Gadolinium-enhanced MRI showed ring enhancement of the lesion (Figure 2(c)). ASL of MRI showed decreased blood flow in both the capsule and content of the lesion (Figure 2(d)). The radiological findings of our case were compatible with CEIH. Therefore, no surgical intervention was performed.

Figure 2.

The cyst content showed a high intensity on both (a) T1- and (b) T2-weighted images. MRI in the third month revealing a cystic lesion with ring enhancement (c). ASL of the lesion showing a decrease of cerebral blood flow (d). (e) MRI obtained 16 months after onset demonstrating the mass size slightly decreasing and perifocal edema improving. The intensity of the content has not significantly changed from the MRI in the third month.

CT in the 10th month showed improvement of the edema around the lesion (Figure 1(c)). MRI obtained 16 months after onset showed a slight decrease of the lesion size (Figure 2(e)). However, the lesion still had high-intensity content. As of the 16th month of the clinical course, he had developed no new symptoms.

Discussion

Intracerebral hematoma becomes encapsulated and expands with repeated internal bleeding on rare occasions.⁷ CEIH was first reported in 1981.⁴ It is characterized by the presence of a fibrotic capsule, which histologically resembles the outer capsule of chronic subdural hematoma and is thought to grow due to repeated bleeding from the new blood vessels in the capsule.^5,6 CEIH sometimes shows progressing symptoms like a brain tumor.³ Radiological examinations revealed ring enhancement, mimicking a brain tumor on CT and MRI. We treated a patient with intracerebral hematoma, and serial radiological examinations were performed. Our patient had a hematoma which showed low-level absorption and became chronic. During the period in which the hematoma became chronic, radiological examinations were repeated. The findings of CT or MRI were compatible with those of previously reported CEIH cases.^3,5,6,8 The gold standard of diagnosis for CEIH is pathological examination. In our case, the course of the disease was followed from the onset to chronic stage for 16 months. Therefore, the diagnosis was not confused as a tumor. And operation was not performed, because the lesion did not grow or cause symptoms. However, if the first radiological examination is done after encapsulation, the presence of a brain tumor may be suspected.

There are two MRI methods to evaluate perfusion in the brain, dynamic susceptibility contrast (DSC) and ASL.⁹ For DSC, intravenous administration of contrast medium (CM) is necessary. On the other hand, ASL images can be obtained without injection of CM. Therefore, ASL is easy to perform compared to DSC. This is the first report describing a case of CEIH which was examined by ASL. Our case did not show an increase of cerebral blood flow (CBF) in either the capsule or content on ASL. Fujii et al. reported that it required approximately 1 month for encapsulation of the hematoma.² A capsule was formed due to a continuing inflammatory response like chronic subdural hematoma. The capsule of CEIH is like the outer membrane of a chronic subdural hematoma, consisting of collagen fibers with a neovasculature.¹ Although the outer membrane of the chronic subdural hematoma is rich in small vessels, the density of the vessels may be much less than in a hypervascular tumor. In fact, the outer membrane of a chronic subdural hematoma did not show hyperperfusion on ASL (unpublished observation). In cases of a cystic brain tumor such as metastasis or glioblastoma, a capsule with rich vascularity is shown as a hyperperfused rim on ASL.¹⁰ ASL usually shows increased blood flow in the capsule of a cystic tumor. Although CT and MRI findings of CEIH are similar to those of a brain tumor, blood flow examined by ASL is different between the two conditions. Therefore, ASL might be a supplemental technique to distinguish CEIH from a cystic hypervascular brain tumor.

ASL images are usually obtained using gradient-echo sequences (GE).¹¹ This sequence is susceptible to hemoglobin byproducts in cases with intracranial hemorrhages. To identify a hemorrhagic lesion containing paramagnetic compounds, susceptibility weighted images (SWI) is useful. SWI is commonly used to detect small amounts of hemorrhage, blood products and changes of iron content, which may not be apparent in other sequences.¹² In our institute, ASL is obtained using spin-echo sequences (SE), not GE.¹³ SE is less susceptible to paramagnetic compounds than GE. Therefore, ASL obtained using SE sequences has less artifact due to hemoglobin byproducts than ASL using GE. And more accurate information about CBF in cases with intracranial hemorrhage can be obtained on SE-based ASL.

Conclusion

Although CEIH is a rare entity, ASL of MRI might be a useful modality to distinguish CEIH from a cystic brain tumor.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of interest

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.