Characterization of Brown Adipose Tissue in a Diabetic Mouse Model with Spiral Volumetric Optoacoustic Tomography

Purpose

Diabetes is associated with a deterioration of the microvasculature in brown adipose tissue (BAT) and with a decrease in its metabolic activity. Multispectral optoacoustic tomography has been recently proposed as a new tool capable of differentiating healthy and diabetic BAT by observing hemoglobin gradients and microvasculature density in cross-sectional (2D) views. We report on the use of spiral volumetric optoacoustic tomography (SVOT) for an improved characterization of BAT.

Procedures

A streptozotocin-induced diabetes model and control mice were scanned with SVOT. Volumetric oxygen saturation (sO₂) as well as total blood volume (TBV) in the subcutaneous interscapular BAT (iBAT) was quantified. Segmentation further enabled separating feeding and draining vessels from the BAT anatomical structure.

Results

Scanning revealed a 46 % decrease in TBV and a 25 % decrease in sO₂ in the diabetic iBAT with respect to the healthy control.

Conclusions

These results suggest that SVOT may serve as an effective tool for studying the effects of diabetes on BAT. The volumetric optoacoustic imaging probe used for the SVOT scans can be operated in a handheld mode, thus potentially providing a clinical translation route for BAT-related studies with this imaging technology.

     

Treatment of severe osteochondral defects of the knee by combined autologous bone grafting and autologous chondrocyte implantation using fibrin gel

Purpose

Severe symptomatic and unstable osteochondral defects of the knee are difficult to treat. A variety of surgical techniques have been developed. However, the optimal surgical technique is still controversial. We present a novel technique in which autologous bone grafting is combined with gel-type autologous chondrocyte implantation (GACI).

Methods

Isolated severe osteochondral defects of the medial or lateral femoral condyle were treated by a two-step procedure. Firstly, chondrocytes were harvested during arthroscopy and cultured for 6?weeks. Secondly, a full thickness corticospongious autologuos bone graft, harvested from the medial or lateral femur condyle, is impacted in the defect and covered by GACI. The fibrin gel fills up to the exact shape of the chondral lesion and polymerizes within 3?min after application.

Results

From 2009 to 2011, 9 patients, median age 35?years (range 23–47), were treated by the combined autologous bone grafting and GACI technique. Median defect size was 7.1?cm² (range 2.5–12.0), and median depth of the lesion was 0.9?cm (range 0.8–1.2). Median follow-up was 9?months (range 6–12?months). Six patients were available for 12-month follow-up. The mean IKDC score showed a 6-month improvement from 35 (SD?±?16) to 51 (SD?±?18) (n?=?9; p?=?0.01), and a 1-year improvement from 35 (SD?±?16) to 57 (SD?±?20) (n?=?6; p?=?0.03). The mean KOOS improved from 44 (SD?±?16) to 62 (SD?±?19) (n?=?9; p?=?0.07) at 6-month follow-up and from 44 (SD?±?16) to 65 (SD?±?24) (n?=?6; p?=?0.1) at 12-month follow-up. There was one failure that needed conversion to a unicompartmental knee arthroplasty.

Conclusion

Combined autologous bone grafting and GACI may offer an alternative surgical option for severe and unstable osteochondral defects of the knee.

Level of evidence

IV.     

Assessment of cartilage repair after chondrocyte transplantation with a fibrin-hyaluronan matrix--correlation of morphological MRI, biochemical T2 mapping and clinical outcome

Objective

To evaluate change over time of clinical scores, morphological MRI of cartilage appearance and quantitative T2 values after implantation with BioCart™II, a second generation matrix-assisted implantation system.

Methods

Thirty-one patients were recruited 6–49 months post surgery for cartilage defect in the femoral condyle. Subjects underwent MRI (morphological and T2-mapping sequences) and completed the International Knee Documentation Committee (IKDC) questionnaire. MRI scans were scored using the MR Observation of Cartilage Repair Tissue (MOCART) system and cartilage T2-mapping values were registered.Analysis included correlation of IKDC scores, MOCART and T2 evaluation with each other, with implant age and with previous surgical intervention history.

Results

IKDC score significantly correlated with MOCART score (r = −0.39, p = 0.031), inversely correlated with previous interventions (r = −0.39, p = 0.034) and was significantly higher in patients with longer follow-up time (p = 0.0028).MOCART score was slight, but not significantly higher in patients with longer term implants (p = 0.199).T2 values were significantly lower in patients with longer duration implants (p < 0.001). This trend was repeated in patients with previous interventions, although to a lesser extent.

Conclusions

Significant improvement with time from BioCart™II implantation can be expected by IKDC scoring and MRI T2-mapping values. Patients with previous knee operations can also benefit from this procedure.