Radiographic progression of knee osteoarthritis is associated with MRI abnormalities in both the patellofemoral and tibiofemoral joint.

OBJECTIVE: To investigate patterns of MRI abnormalities in the patellofemoral (PFJ) and tibiofemoral joint (TFJ) and their association with radiographic progression, using hypothesis free analyses. DESIGN: 205 patients from the GARP study with symptomatic OA at multiple sites (mean age 60 years, 80% woman, median BMI 26 kg/m(2)), underwent knee MRI at baseline. Cartilage damage, osteophytes, cysts, bone marrow lesions (BMLs) and effusion/synovitis were scored according to a validated scoring method. Baseline and 6-year TFJ and PFJ radiographs were scored (0-3) for JSN and osteophytes according to OARSI and Burnett atlases, respectively; progression was defined as ≥1 point increase. Baseline patterns of MRI abnormalities derived from principal component analysis (PCA) were associated with progression using adjusted generalized estimating equations (GEE). RESULTS: PCA resulted in extraction of six components, explaining 69% of variance. In 29% and 29% of 133 patients with follow-up the TFJ progressed, whereas in 15% and 9% the PFJ progressed for osteophytes and JSN, respectively. Component 1 (cartilage damage of the PFJ and osteophytes of both joints) was statistically significant associated with TFJ JSN progression and PFJ osteophyte progression. Component 2 (all lateral PFJ abnormalities except osteophytes) was associated with JSN/osteophyte progression in the PFJ alone, whereas component 3 (all medial TFJ abnormalities except osteophytes) was associated with JSN and osteophyte progression in both PFJ and TFJ. CONCLUSION: Baseline structural damage and bone turnover activity, as reflected by BMLs, seem to be involved in knee OA progression. Moreover, progression in PFJ and TFJ seems to be related.

Brodie's abscess revisited.

Radiology plays an important role in the diagnosis of a Brodie's abscess, as can be difficult for a clinician to identify the disease using clinical information alone. A Brodie's abscess is clinically difficult to diagnose because patients typically have mild local symptoms, few or no constitutional symptoms, and near normal laboratory values. Furthermore, a Brodie's abscess may mimic various benign and malignant conditions, resulting in delayed diagnosis and treatment. The most frequently made incorrect diagnosis is that of a primary bone tumor. The present pictorial review summarizes imaging clues to the diagnosis of a Brodie's abscess, such as the serpentine sign on conventional radiographs and the penumbra sign seen on Magnetic Resonance (MR) images. A Brodie's abscess is difficult to diagnose, however, once diagnosed, it is a curable disease with a 100% cure rate.

MR imaging of articular cartilage at 1.5T and 3.0T: comparison of SPGR and SSFP sequences.

OBJECTIVE: To compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5 T and a 3.0 T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences. METHODS: Both knees of five volunteers were scanned at 1.5 T and at 3.0 T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements. RESULTS: For 3D-SPGR, cartilage SNR efficiencies at 3.0 T increased compared to those at 1.5 T by a factor of 1.83 (range: 1.40-2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81-2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95-2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5 T by a factor of 2.12 (range: 1.75-2.47), for FS-SSFP by a factor 2.11 (range: 1.58-2.80) and for Dixon SSFP by a factor 2.39 (range 2.09-2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28 mm. CONCLUSION: Articular cartilage imaging of the knee on a 3.0 T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5 T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5 T and 3.0 T scanners or between the three different sequences.

Central osteophytes in the knee: prevalence and association with cartilage defects on MR imaging.

OBJECTIVE: The objective of this study was to determine the prevalence and location of central osteophytes in patients referred for MR imaging of the knee and the relationship of central osteophytes to articular cartilage defects, marginal osteophytes, meniscal tears, and anterior cruciate ligament tears as seen on MR imaging. MATERIALS AND METHODS: Two hundred consecutive patients referred for MR imaging of the knee were evaluated for central osteophytes, articular cartilage defects, marginal osteophytes, meniscal tears, and anterior cruciate ligament tears. A 1.5-T scanner was used, and assessments were made by consensus of two experienced musculoskeletal radiologists. Seven patients were excluded, leaving 193 patients in the study population. RESULTS: The prevalence of central osteophytes in the knee was 15% (35 central osteophytes in 29 patients). Patients with central osteophytes were older (mean age, 52 years versus 38 years), weighed more (mean weight, 204 lb [92 kg] versus 174 lb [78 kg]), had more articular cartilage defects (mean, 4.3 versus 1.3), and had more marginal osteophytes (mean, 3.9 versus 1.1) than patients without central osteophytes (p < 0.0001, Student's t test). Patients with central osteophytes were more likely to have a meniscal tear (p = 0.004, chi-square test), but they were not more likely to have an anterior cruciate ligament tear. All central osteophytes were associated with articular cartilage defects at the same location, which were full or near-full thickness on MR imaging for 32 of 35 central osteophytes. CONCLUSION: Central osteophytes are common in patients referred for MR imaging of the knee. When central osteophytes are seen in the knee there is a high likelihood of an associated full thickness or near-full thickness articular cartilage defect.