Intravoxel incoherent motion and diffusion kurtosis imaging at 3T MRI: Application to ischemic stroke

BACKGROUND AND PURPOSE

The DKI-IVIM model that incorporates DKI (diffusional kurtosis imaging) into the IVIM (Intravoxel Incoherent Motion) concept was investigated to assess its utility for both enhanced diffusion characterization and perfusion measurements in ischemic stroke at 3 T.

METHODS

Fifteen stroke patients (71 ± 11 years old) were enrolled and DKI-IVIM analysis was performed using 9 b-values from 0 to 1500 s/mm² chosen with the Cramer-Rao-Lower-Bound optimization approach. Pseudo-diffusion coefficient D*, perfusion fraction f, blood flow-related parameter fD*, the diffusion coefficient D and an additional parameter, the kurtosis, K were determined in the ischemic lesion and controlateral normal tissue based on a region of interest approach. The apparent diffusion coefficient (ADC) and arterial spin labelling (ASL) cerebral blood flow (CBF) parameters were also assessed and parametric maps were obtained for all parameters.

RESULTS

Significant differences were observed for all diffusion parameters with a significant decrease for D (p < 0.0001), ADC (p < 0.0001), and a significant increase for K (p < 0.0001) in the ischemic lesions of all patients. f decreased significantly in these regions (p = 0.0002). The fD* increase was not significant (p = 0.56). The same significant differences were found with a motion correction except for fD* (p = 0.47). CBF significantly decreased in the lesions. ADC was significantly positively correlated with D (p < 0.0001) and negatively with K (p = 0.0002); K was also negatively significantly correlated with D (p = 0.01).

CONCLUSIONS

DKI-IVIM model enables for simultaneous cerebral perfusion and enhanced diffusion characterization in an acceptable clinically acquisition time for the ischemic stroke diagnosis with the additional kurtosis factor estimation, that may better reflect the microstructure heterogeneity.

Chikungunya, a Risk Factor for Guillain-Barré Syndrome

In a matched case-control study where 24 cases developed Guillain-Barré syndrome (GBS) during the 2014 chikungunya outbreak in the French West Indies and 72 controls were blood donors during the same period, chikungunya infection was a risk factor for GBS (odds ratio, 8.3; 95% confidence interval, 2.3-29.7; P = .001).

[Bilateral intracerebral angioplasty in a patient with stroke caused by giant cell arteritis]

INTRODUCTION

Giant cell arteritis is the most frequent vasculitis and can cause stroke in about 4% of the patients. The mechanism is often hemodynamic in relation with an arterial stenosis or occlusion. Optimal treatment remains to be defined. Outcome is often poor.

CASE REPORT

We report the case of a 78-year-old patient, with giant cell arteritis who developed neurological deterioration after the onset of the corticotherapy. Brain MRI revealed bilateral stroke caused by multiple preocclusive internal carotid stenosis. The patient was treated successfully with angioplasty and stenting.

CONCLUSION

Endovascular treatment could constitute an interesting alternative for patients with giant cell arteritis associated with neurological deterioration after a first episode of stroke because of hemodynamic instability or at stroke recurrence. For these patients, the usual medical treatment appears to be insufficient.

[Star fruit (Averrhoa carambola) toxic encephalopathy]

Ingestion of star fruit (Averrhoa carambola) can induce severe intoxication in subjects with chronic renal failure. Oxalate plays a key role in the neurotoxicity of star fruit. We report the cases of two patients with unknown chronic renal insufficiency who developed severe encephalopathy after ingestion of star fruit. The two patients developed intractable hiccups, vomiting, impaired consciousness and status epilepticus. Diffusion-weighted MR imaging showed cortical and thalamic hyperintense lesions related to epileptic status. They improved after being submitted to continuous hemofiltration which constitutes the most effective treatment during the acute phase.