Diffusion-weighted MRI, dynamic susceptibility contrast MRI and ultrasound perfusion quantification of denervated muscle in rabbits.

OBJECTIVE: The purpose of this study was to assess denervated muscle perfusion using dynamic susceptibility contrast MRI (DSCMRI) and contrast-enhanced ultrasound (CEUS), and to measure denervated muscle apparent diffusion coefficient (ADC) on b1000 diffusion-weighted MRI (DWMRI) at 3 T in order to clarify whether muscle denervation leads to an increase in the extracellular extravascular space, or an increase in blood flow-or both. MATERIALS AND METHODS: Axotomy of the right sciatic nerve of six white rabbits was performed at day 0. At day 9, hind limb muscles MRI and CEUS were performed to assess the consequences of denervation and both semimembranosus muscles of each rabbit were explanted for histological studies. Signal intensity on T2- and T1-weighted MRI, ADC on DWMRI, maximum signal drop (MSD) on DSCMRI and the area under the curve (AUC) on CEUS were measured over circular regions of interest (ROI), in both semimembranosus muscles. Non-parametric Wilcoxon matched-pairs tests were used to assess the mean differences between denervated and normal muscles. RESULTS: T2 fat-saturated (FS) MRI studies showed a strong signal in the right semimembranosus muscles compared with the left side, and gadolinium enhancement was observed on T1 FS MRI. Denervated muscles show a significant increase in ADC on DWMRI (p < 0.01) and a significant signal enhancement on DSCMR imaging (p < 0.05) and on first-pass CEUS (p < 0.05). CONCLUSION: The results of this study--based on perfusion- and diffusion-weighted images--suggest that, after denervation, both increased blood flow through muscle tissue and expansion of the extracellular water volume are present.

Leptomeningeal carcinomatosis and sensorineural hearing loss: correlation of labyrinthine enhancement patterns with symptoms.

OBJECTIVES: The purpose of this study was to investigate the correlation between hearing loss and inner ear enhancement in patients suffering from leptomeningeal carcinomatosis (LC) involving the internal acoustic canal (IAC). Previous studies have only reported an association between IAC enhancement and sensorineural deafness. MATERIAL AND METHODS: In a prospective study conducted from 2005 to 2007, 14 patients with LC involving the IAC underwent high-resolution MRI and otolaryngology examination. MRI images were analyzed by two experienced radiologists who were blinded to audiologic investigation results. RESULTS: Three (21%) patients had IAC and inner ear enhancement on gadolinium-weighted MRI. All three had a sensorineural hearing loss. Eleven (79%) patients had IAC enhancement without inner ear enhancement. Nine of these 11 patients were free of sensorineural hearing loss. Only two of them had sensorineural deafness. CONCLUSION: These findings are suggestive of a relation between hearing loss and inner ear enhancement in leptomeningeal carcinomatosis, as previously reported for bacterial meningitis. However, further investigations, including radiopathological correlation and a larger number of patients, are warranted to confirm these preliminary results.

[Image-guided ablation of bone tumors: review of current techniques]. / Ablation des tumeurs osseuses sous contrôle de l'imagerie: revue des techniques actuelles.

Multiple interventional radiology techniques are available for percutaneous ablation of bone tumors: alcohol, laser, radiofrequency, microwave, ultrasound, and cryogenic ablation. Several indications have already been validated, including radiofrequency ablation of osteoid osteoma and bone metastases, with results superior to conventional treatment. More indications should be added over the coming years. The purpose of this article is to review the principles of the different ablation techniques, summarize their respective indications and results and discuss their implementation and the eventual combination with cementoplasty techniques.