In vivo rat knee cartilage volume measurement using quantitative high resolution MRI (7 T): feasibility and reproducibility.

OBJECTIVES: to assess reliability and reproducibility of quantitative MRI (7 T) in assessing rat femoro-tibial cartilage volume. METHODS: 5 healthy rat knees were scanned in vivo using a 7 T experimental imager. Sagittal high resolution 3D Gradient Echo with fat suppression sequences were performed with a dedicated home-made 2-elements array coil. 3D MRI sets were used to perform manual segmentation of the 3 cartilage compartments (femoral groove, medial and lateral tibial plateaus) by using a tactile screen. To evaluate inter- and intra-observer reproducibilities, the segmentation procedure was done blindly by two trained observers. One observer repeated the operation twice, with a period of 10 months between both readings. RESULTS: the mean duration to manually segment all the slices covering the cartilaginous joint was 4 hours. On the one hand, the inter-observer root mean square of coefficients of variation was 9.1%, 6.2%, 9.6% for the femoral, medial and lateral tibial compartments respectively. On the other hand, the intra-observer reproducibility was 2.1%, 3.2%, 2.5% for these cartilage compartments cited above. CONCLUSION: the image quality obtained at 7 Teslas with our dedicated coil allowed segmentation of the cartilage compartments with good reproducibility. This study demonstrated that MRI is a useful technology to provide a non-invasive and reliable assessment of rat knee cartilage volume.

[Purple urine bag syndrome]. / Purple urine bag syndrome.

INTRODUCTION: The report of purple discoloration in a urinary drainage system, known as Purple Urine Bag Syndrome (P.U.B.S.) is rarely described in the literature. OBSERVATION: In an 85 year-old woman, with permanent indwelling urinary catheter, the appearance of purple coloration in the urine collecting bag, without change in the colour of the urine, was observed four times in one year. During these different episodes, a Gram negative lower urinary infection diagnoses. The germs identified were Providencia stuartii and Citrobacter koseri. Symptoms resolved completely after treatment with ceftriaxone. DISCUSSION: The clinical and biological symptoms usually described in cases of P.U.B.S. are observed in the medical history of this elderly woman: indwelling catheter with delay before onset of coloration greater than 15 days following catheterization, alkaline urinary pH, Gram negative lower urinary tract infection. However, during one of the episodes of PUBS in our patient, Citrobacter koseri was identified, germ not mentioned, as far as we know, in the literature. Moreover, in the published cases, Proteus species was identified as potentially associated with P.U.B.S., but a Proteus mirabilis urinary infection with was diagnosed in our patient, without any purple coloration of the urine in the collection bag.