A characteristic feature of acute haematomas in the brain on echo-planar diffusion-weighted imaging

Temporal changes in extra-axial brain hematoma's signal intensity in magnetic resonance images of trauma patients: A preliminary, technical study

INTRODUCTION

Dating the exact or estimated time of trauma is an important issue facing forensic medicine. Several clinical and radiological methods were used to achieve this purpose. In the recent study, we aimed to track the changes in the signal intensity of the extra-axial brain hematoma using magnetic resonance imaging (MRI) conventional sequences as well as diffusion-weighted imaging (DWI) and the apparent diffusion coefficient (ADC).

MATERIALS AND METHODS

Considering inclusion and exclusion criteria, all patients with blunt head trauma were involved. After proper management., stabilization, and resuscitation, the participants were assessed using conventional sequences of MRI and DWI twenty-four hours, forty-eight hours, and three weeks after the injury. Temporal changes of signal intensity were compared by Wilcoxon ranged test.

RESULTS

Sixteen patients sustaining blunt head trauma were included in this study. The study showed that during the time, diffusion restriction could be seen in an extraaxial hematoma. At the first 24 hours, the signal of hematoma was void in 87.5% of DWI and 100% of ADC. On the second day, they were hypo-signal in 75% of DWI and 100% 0f ADCs, and after three weeks, 100% of cases were hyper-signal in DWI and hypo-signal ADCs.

CONCLUSION

This preliminary study has shown that the DWI can be used to detect and track the extra-axial hematoma. The signal intensity was void during the first twentyfour hours, although it became hypo-signal after 48 hours. Of note, the diffusion restriction is noted after three weeks.

Diffusion-weighted imaging at b1000 for identifying intracerebral hemorrhage: preliminary sensitivity, specificity, and inter-rater variability

BACKGROUND

Noncontrast computed tomography (NCCT) is the gold standard to detect intracerebral hemorrhage (ICH) and ischemic stroke (IS) in patients presenting with acute focal syndromes. Diffusion-weighted magnetic resonance imaging (DW-MRI) obtained at b1000 is highly sensitive to identify acute IS but its sensitivity and specificity to detect ICH has not been systematically studied.

METHODS

Patients with a diagnosis of ICH on NCCT were prospectively enrolled and underwent DW-MRI at b1000. Patients with suspected ischemia and a negative NCCT served as controls. All diffusion-weighted imaging (DWI) scans were evaluated blindly by 4 experienced raters. Sensitivity, specificity, and inter-rater variability of the DWI b1000 scans for detection of ICH were determined.

RESULTS

In this preliminary pilot study, 15 patients with ICH and 17 patients with IS were included. All ICH lesions seen on NCCT showed a typical pattern on DW-MRI at b1000 with a hypointense core surrounded by a hyperintense rim. ICH volumes and size were similar on NCCT and MRI. All cases of IS were identified on the DWI scans but none were apparent on NCCT. The mean sensitivity and specificity of DW-MRI at b1000 for ICH were 94% and 93.5%, respectively, and the inter-rater variability for ICH detection on DWI was excellent (κ = .84).

CONCLUSIONS

DW-MRI at b1000 has a diagnostic yield similar to NCCT for detecting ICH and superior to NCCT for detecting IS. Therefore, DW-MRI may be considered as the initial screening tool for imaging patients presenting with focal neurologic symptoms suggestive of stroke.

Temporal changes in perihematomal apparent diffusion coefficient values during the transition from acute to subacute phases in patients with spontaneous intracerebral hemorrhage

INTRODUCTION

Diffusion-weighted imaging (DWI) studies focusing on apparent diffusion coefficient (ADC) abnormalities have provided conflicting results about the nature and fate of perihematomal edema.

METHODS

We investigated 35 patients with supratentorial spontaneous intracerebral hemorrhage (SICH) by using DWI scanning obtained at 48 h and 7 days after symptom onset. Regional ADC (rADC) values were measured in three manually outlined regions of interest: (1) the perihematomal hyperintense area, (2) 1 cm of normal appearing brain tissue surrounding the perilesional hyperintense rim, and (3) a mirror area, including the clot and the perihematomal region, located in the contralateral hemisphere.

RESULTS

rADC mean levels were lower at 7 days than at 48 h in each ROI (p < 0.00001), showing a progressive normalization of initial vasogenic values. Perihematomal vasogenic rADC values were more frequent (p < 0.00001) at 48 h than at 7 days, whereas perihematomal cytotoxic and normal rADC levels were more represented (p < 0.02 and p < 0.001, respectively) at 7 days than at 48 h. A neurological worsening was more frequent (p < 0.02) in patients with than in those without perihematomal cytotoxic rADC values at 7 days.

CONCLUSION

Our findings suggest that the transition from acute to subacute phases after SICH is characterized by a progressive resolution of perihematomal vasogenic edema associated with an increase in cytotoxic ADC values. In the subset of patients with perihematomal cytotoxic rADC levels in subacute stage after bleeding, irreversible damage development seems to be related to poor clinical outcome.

Voxel-based analysis of apparent diffusion coefficient in perihaematomal oedema: associated factors and outcome predictive value for intracerebral haemorrhage

Objectives The pathophysiology of perihaematomal oedema (PO) surrounding a primary intracerebral haemorrhage (ICH) is complicated and incompletely understood. We prospectively investigated the components of PO with voxel-based analysis of the apparent diffusion coefficient (ADC) value and assessed its predictive value for functional outcome. Design Forty-six patients with ICH who were enrolled for clinical evaluation underwent MRI scans within 24 h after ICH. Based on the ADC value of the ipsilateral voxels divided by the mean ADC value of the contralateral mirror region of interest, the voxels with oedema were classified into three categories: cytotoxic, vasogenic and undetermined. The percentages of cytotoxic and vasogenic oedema were then calculated and correlated with clinical outcome according to the modified Rankin Scale (mRS) at 6 months after ICH. The intraobserver and interobserver reliability of this method were examined using intraclass correlation coefficients. Results The intraclass correlation coefficients showed that analysis using the voxel-based method is highly reliable. Among the clinical variables tested, age and serum creatinine levels were positively correlated with percentage of cytotoxic oedema. Age, history of coronary artery disease, National Institutes of Health Stroke Scale score and percentage of cytotoxic oedema were all associated with mRS at 6 months after ICH. Conclusions The pathophysiological processes within PO are complicated. Voxel-based analysis of ADC values may help to identify the components of PO and may be beneficial for decision making and predicting outcome.

Imagerie de diffusion : principes et applications cliniques

Diffusion MRI gives information that is not available with conventional MRI examinations. It can provide early diagnosis of stroke and helps in diagnosing cerebral lymphoma, cerebral bacterial abscess, and epidermoid cyst. It helps distinguish between vasogenic edema and cytotoxic edema and has prognostic value. Acquisition is fast and should be performed in all neuroradiological examinations.

Evaluation of acute perihematomal regional apparent diffusion coefficient abnormalities by diffusion-weighted imaging

In this study, we investigated 40 patients (18 male, 22 female; mean age = 64.5 +/- 11.0; GCS = 9 to 14) with acute supratentorial spontaneous intracerebral hemorrhage (SICH) at admission by using a 1-tesla magnetic resonance imaging (MRI) unit equipped for single-shot echo-planar spin-echo isotropic diffusion-weighted imaging (DWI) sequences. All DWI studies were obtained within 48 hours after symptom onset. Regional apparent diffusion coefficient (rADC) values were measured in 3 different regions of interest (ROIs) drawn freehand on the T2-weighted images at b 0 s/mm2 on every section in which hematoma was visible: 1) the perihematomal hyperintense area; 2) 1 cm of normal appearing brain tissue surrounding the perilesional hyperintense rim; 3) an area mirroring the region including the clot and perihematomal hyperintense area placed in the contralateral hemisphere. rADC mean values were higher in perihematomal hyperintense and in contralateral than in normal appearing areas (p < 0.001), with increased rADC mean levels in all regions examined. Our findings show that rADC values indicative of vasogenic edema were present in the perihematomal area and in normal appearing brain tissue located both ipsilateral and contralateral to the hematoma, with lower levels in non-injured areas located in the T2 hyperintense rim around the clot.

[Neuroimaging characteristics of intracerebral haematoma]

The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, the diagnosis of hematoma is often obtained by CT scan, however today MRI has proved to be more accurate than CT to detect hemorrhage and to identify an underlying etiology. In some cases, according to the patient age, the medical history and the location of the hematoma, it may be necessary to perform a conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages according to the sequences and the temporal evolution, and to describe special findings which can help to identify an underlying etiology.

Comparison of five MR sequences for the detection of acute intracranial hemorrhage

PURPOSE

To evaluate the respective value of 5 MR sequences to distinguish between stroke patients with and without acute intracerebral hemorrhage (ICH).

METHODS

MR images obtained < or =6 h after stroke onset of 86 patients (43 ICH, 43 non-ICH) were reviewed by 3 observers who looked for signs of acute ICH on each image set [T(1) and T(2) gradient echo (GRE), FLAIR, T(2)-EPI and DWI], presented separately.

RESULTS

For the identification of ICH, intraobserver and interobserver concordance were at least kappa = 0.95 for all sequences. Of all interpretations, 7 (0.4%) were erroneous, with sensitivity and specificity of FLAIR, T(2)-EPI and DWI reaching 100%; GRE sensitivity and specificity were 100% and 95-97.5%, respectively; T(1) sensitivity and specificity were 97.3-100% and 97.4-100%, respectively. All 4 patients misclassified on one pulse sequence were correctly classified on all the other sequences.

CONCLUSION

In the setting of acute stroke, each of the 5 studied sequences enables ICH and non-ICH patients to be distinguished with high sensitivity and specificity.

Stroke Magnetic Resonance Imaging Is Accurate in Hyperacute Intracerebral Hemorrhage

Background and Purpose— Although modern multisequence stroke MRI protocols are an emerging imaging routine for the diagnostic assessment of acute ischemic stroke, their sensitivity for intracerebral hemorrhage (ICH), the most important differential diagnosis, is still a matter of debate. We hypothesized that stroke MRI is accurate in the detection of ICH. To evaluate our hypotheses, we conducted a prospective multicenter trial.

Methods— Stroke MRI protocols of 6 university hospitals were standardized. Images from 62 ICH patients and 62 nonhemorrhagic stroke patients, all imaged within the first 6 hours after symptom onset (mean, 3 hours 18 minutes), were analyzed. For diagnosis of hemorrhage, CT served as the “gold standard.” Three readers experienced in stroke imaging and 3 final-year medical students, unaware of clinical details, separately evaluated sets of diffusion-, T2-, and T2*-weighted images. The extent and phenomenology of the hemorrhage on MRI were assessed separately.

Results— Mean patient age was 65.5 years; median National Institutes of Health Stroke Scale score was 10. The experienced readers identified ICH with 100% sensitivity (confidence interval, 97.1 to 100) and 100% overall accuracy. Mean ICH size was 17.3 mL (range, 1 to 101.5 mL). The students reached a mean sensitivity of 95.16% (confidence interval, 90.32 to 98.39).

Conclusions— Hyperacute ICH causes a characteristic imaging pattern on stroke MRI and is detectable with excellent accuracy. Even raters with limited film-reading experience reached good accuracy. Stroke MRI alone can rule out ICH and demonstrate the underlying pathology in hyperacute stroke.