Patients with Type 2 Diabetes Exhibit a More Mineralized Deep Cartilage Layer Compared with Nondiabetic Controls: A Pilot Study

Abstract

Objective: To assess differences in biochemical composition of the deep cartilage layer in subjects with type 2 diabetes mellitus (T2DM) and nondiabetic controls using UTE (ultra-short echo time) T2* mapping and to investigate the association of vascular health and UTE T2* measurements.

Design: Ten subjects with T2DM matched for age, sex, and body mass index with 10 nondiabetic controls. A 3D UTE sequence with 6 echo times was acquired using 3T magnetic resonance imaging of the knee. For UTE T2* analysis, the deep cartilage layer was segmented and analyzed in 5 compartments (patella, medial, and lateral femur and tibia). The ankle brachial index (ABI) was obtained in all subjects. Linear regression analyses were used to assess associations of T2DM and UTE T2* relaxation times and the associations of ABI measurements and UTE measurements.

Results: Compared with nondiabetic controls, T2DM subjects had significantly lower mean T2*-UTE in the patella (mean difference 4.87 ms; 95% confidence interval [CI] 1.09-8.65; P = 0.015), the lateral tibia (mean difference 2.26 ms; 95% CI 0.06-4.45; P = 0.045), and the lateral femur (mean difference 4.96 ms; 95% CI 0.19-9.73; P = 0.043). Independent of diabetic status, subjects with higher ABI values, indicating better vascular health, had higher T2*-UTE of the patella (coefficient 15.2; 95% CI 3.3-21.4; P = 0.017), the medial tibia (coefficient 9.8; 95% CI 1.0-18.6; P = 0.031), and the lateral femur (coefficient 18.8; 95% CI 3.3-34.3; P = 0.021).

Conclusions: T2*-UTE measurements of the deep cartilage layer were consistently lower in subjects with T2DM and in subjects with impaired vascular health, likely indicating increased mineralization of this layer.

Keywords: MRI; diabetes; knee.

Figure 1.

Example of ultrashort echo time–enhanced (UTE) T2* segmentation splines of the lateral tibia compartment, with white dashed line indicating the border of the articular cartilage. The distinct linear signal intensity above the subchondral bone of the deep calcified layer of articular cartilage (A), was manually segmented manually on the first echo (B). Finally, UTE T2* values were calculated on a pixel-by-pixel basis using a monoexponential decay model as fitting function for the signal intensity (C).

Figure 2.

(A and B) Sagittal 3-dimensional ultrashort echo time–enhanced (UTE) T2* sequences demonstrate the distinct linear signal intensity of the deep calcified layer of the articular cartilage (black arrows) and segmentation splines of the patella compartment. (C) T2*-UTE maps were computed using a monoexponential decay model as fitting function for the signal intensity from the multislice multiecho (MSME) images on a pixel-by-pixel basis with blue color indicating low values and red color indicating high UTE T2* values. (D) UTE color map of the patella compartment (values are in milliseconds).

Figure 3.

Sagittal ultrashort echo time–enhanced (UTE) T2* color map (values are in milliseconds) of the deep calcified cartilage layer of the lateral tibia of a nondiabetic control (A), and a subject with type 2 diabetes mellitus (B), with white dashed line marking the border of the articular cartilage. Blue color indicates low, while red color indicates high T2*-UTE values. In comparison to the nondiabetic control, UTE T2* measurements of the deep calcified cartilage layer of the diabetic subject show lower values (blue), compatible with increased mineralization.