Cartilage degeneration post-meniscectomy performed for degenerative disease versus trauma: data from the Osteoarthritis Initiative.

OBJECTIVE: To compare the extent of cartilage deterioration in knees with prior meniscal resection related to trauma versus knees with resection related to degenerative disease, and to compare cartilage deterioration in knees with meniscal surgery to knees without meniscal surgery, controlling for prior knee trauma. MATERIALS AND METHODS: In this cross-sectional study, we assessed cartilage deterioration in right knees of Osteoarthritis Initiative participants: (i) with meniscal surgery due to injury (n = 79); (ii) matched control knees with a prior injury but without meniscal surgery (n = 79); (iii) with meniscal surgery but without preceding injury (n = 36); and (iv) matched control knees without meniscal surgery or prior knee injury (n = 36). Cartilage composition was measured using T2 measurements derived using semi-automatic cartilage segmentation of the right. Linear regression analysis was used to compare compartmental values of T2 between groups. RESULTS: Comparing the mean T2 values in surgical cases with and without injury our results did not show significant differences (group i vs. iii, p > 0.05). However, knees with previous meniscal surgery showed significantly (p < 0.001) higher mean T2 values across all compartments (i.e., global T2) when compared to those without meniscal surgery for both knees with a history of trauma (group i vs. ii) and knees without prior trauma (group iii vs. iv). Similar results were obtained when analyzing the compartments separately. CONCLUSIONS: Cartilage deterioration, assessed by T2, is similar in knees undergoing meniscal surgery after trauma and for degenerative conditions. Both groups demonstrated greater cartilage deterioration than nonsurgical knees, controlling for prior knee injury.

Preoperative evaluation of pelvine lymph node metastasis in high risk prostate cancer with intravoxel incoherent motion (IVIM) MRI.

OBJECTIVES: To evaluate benign and malignant pelvine lymph nodes in prostate cancer patients with biexponential intravoxel incoherent motion (IVIM) MRI of the prostate prior to radical prostatectomy. METHODS: The ethics committee approved this retrospective study with waiver of informed consent. From February 2012 to November 2013 43 patients with histopathologically proven prostatic cancer were included. All patients were examined applying a standardized MRI protocol including IVIM diffusion weighted imaging with multiple b-values ranging from 0 to 950 s/mm². MR imaging was performed one day prior to radical prostatectomy. Thereafter, extended lymph node resection was performed. For each MRI all visible lymph nodes were registered and calculated as individual regions of interest. These findings were correlated with postoperative pathology. The apparent diffusion coefficient ADC, the diffusion coefficient D and the perfusion fraction f were calculated from IVIM DWI using a biexponential fit. RESULTS: A total of 120 lymph nodes were detected on MRI. 95 of these were determined as benign and 25 as malignant. The average ADC was significantly lower in malignant compared to benign lymph nodes (0.88 × 10-³ vs 1.67 × 10-³ mm²/s, p < 0.001). Likewise, the average diffusion coefficient D was significantly lower in lymph node metastasis (0.54 × 10-³ vs 1.10 × 10-³ mm²/s, p < .001). The signal rate due to perfusion was significantly higher in malignant compared to benign nodes (33.4% vs. 27.1%, p = 0.02). CONCLUSIONS: Applying biexponential IVIM MRI demonstrates significant differences in diffusion parameters ADC and D, as well as in the perfusion fraction f for benign and malignant lymph nodes. Therefore, IVIM might help to further improve the preoperative assessment of lymph nodes in MRI.