Perfusion imaging in renal diseases.

Functional imaging of the kidney using radiological techniques has a great potential of development because the functional parameters, which can be approached non-invasively, are multiple. CT can provide measurement of perfusion and glomerular filtration but has the inconvenient to deliver irradiation and potentially nephrotoxicity due to iodine agents in this context. Sonography is able to evaluate perfusion only but quantification remains problematic. Therefore, MR imaging shows the greatest flexibility measuring blood volume and perfusion as well as split renal function. The main applications of perfusion imaging of the kidney are vascular diseases, as renal artery stenosis, renal obstruction and follow-up of renal tumors under antiangiogenic therapy. However, full clinical validation of these methods and the evaluation of their clinical impact are still often worthwhile.

Diffusion MRI of the neck of the femur in Legg-Calve-Perthes disease: a preliminary study.

PURPOSE: To evaluate diffusion MR imaging of the neck of the femur in Legg-Calve-Perthes disease (LCPD). MATERIAL AND METHODS: This is a prospective study in 27 children followed for unilateral LCPD. Forty-six MRIs were carried out with bilateral quantification of the apparent diffusion coefficient (ADC) of the neck of the femur. The intra- and inter-observer variability of the ADC measurements was evaluated. The association between the ADC and age as well as the healthy or pathological status of the neck of the femur and the Catterall classification were looked for. RESULTS: Intra- and inter-observer reproducibility of the ADC measurements was excellent. A statistically significant negative correlation between the ADC of the healthy neck of the femur and age was found. There was a significant increase in the ADC of the pathological neck of the femur compared to the healthy neck. The ratio of the pathological neck ADC and the healthy neck ADC was significantly associated with the Catterall classification. CONCLUSION: The quantification of the ADC of the neck of the femur is reproducible. This could be useful in the treatment of LCPD, where there is an early and significant increase in the ADC on the pathological side. This increase could have a prognostic value, as it is correlated with the Catterall classification.

Radiologically-guided thermal ablation of renal tumours.

Thermal ablation techniques for renal tumours have become the norm in surgically at-risk patients. These percutaneous treatments are locally effective, particularly for tumours measuring less than 4cm. Larger tumours may be treated by adapting the technique and strategy. Multidisciplinary discussion is essential before any decision, in order to decide on the most appropriate technique. Radiofrequency is simple, effective and inexpensive. Cryotherapy is more complex and should be preferred when the tumour is large or there is vascular or urinary tract contact. Microwaves can be used to treat larger tumours. Morbidity is low, but good knowledge of these techniques and of dissection is required to avoid injury to neighbouring digestive or urinary structures.