[Comparison of magnetic resonance Spin-echo sequences and fat-suppressed sequences in bone diseases]

Thirty-two patients affected with skeletal conditions were examined with MRI using Short TI Inversion Recovery sequence and Spectral Presaturation with Inversion Recovery (SPIR) sequence as well as Spin-Echo (SE) T1-weighted sequence and Fast Spin-Echo (FSE) T2-weighted sequence to compare their value in the assessment of skeletal lesions. SPIR sequence was performed after intravenous injection of Gd-DTPA. The lesions included primary bone tumors (10 cases: 1 osteosarcoma, 1 periosteal sarcoma, 1 Ewing's sarcoma, 1 chondrosarcoma, 2 non-ossifying fibromas, 1 chondroma, 1 chondromyxoid fibroma, 1 desmoplastic fibroma and 1 bone cyst), metastases (7 cases: 3 prostate, 3 breast, 1 lung-squamous cell carcinoma), infections (12 cases: 9 osteomyelitis, 3 spondylodiscitis), sacroiliitis (1 case) and posttraumatic bone bruise (2 cases of bone marrow edema). The four sequences were compared by using both qualitative and quantitative evaluation. Qualitative evaluation showed that STIR sequence was better than SPIR sequence (performed with Gd-DTPA) for lesion conspicuity (p < .016) and for signal intensity uniformity (p < .03). Compared with SE T1 and FSE T2 sequences, fat-suppressed sequences were superior for conspicuity, margins, and extension of the lesions (range of p < .001-.017). Only SPIR with Gd-DTPA sequence, compared with SE T1 sequence for lesion conspicuity was not statistically significantly different. Quantitative evaluation showed statistically significant higher values of percent contrast (%C) and contrast-to-noise ratio (C/N) for STIR sequence compared with SPIR sequence (%C p < .004; C/N p < .040). This study suggests that STIR sequence and SE T1-weighted sequence provide high sensitivity in lesion detection and good anatomical definition. The use of a fat-suppressed sequence with Gd-DTPA can be useful for lesion characterization.

[Magnetic resonance assessment of knee joint hyaline cartilage according to age, sex, and body weight]

To study the MR appearance of knee joint hyaline cartilage, 120 subjects were examined with MRI of the knee. Axial SE proton-density (PD) and T2, GE T1 and GE-MTC sequences were used, as well as coronal SE T1 and sagittal SE PD and T2 sequences. At the patellar and femorotibial cartilages the following variables were investigated: thickness, surface, signal intensity and visibility. Moreover, the three patellar sequences were compared qualitatively, by giving a 1-to-4 score to the images, depending on their yield in the four variables. As for articular cartilage thickness, a statistically significant difference was found between men and women in nearly all measurement sites, the mean values being always higher in men. A statistically significant inverse correlation between cartilage thickness and age was found, in men only, at the three load-bearing regions of the medial femoral condyle. Cartilage surface was irregular and/or its signal intensity altered in 28% of patients at the femoral condyles, while the cartilage of tibial plates exhibited normal surface and homogeneous signal intensity in most cases. The visibility rate of trilaminar cartilage was 82.5% for the medial femoral condyle, 87.5% for the lateral femoral condyle, 70% for the patella, 12.5% for the medial tibial plateau and 14.5% for the lateral tibial plateau. No statistically significant correlation was found between cartilage thickness, surface, signal intensity and visibility and age, sex, and body weight. The GE sequence was the best tool to study cartilage thickness and signal intensity, while the SE T2 sequence was the most accurate one to depict the articular surface and, together with the PD SE sequence, to visualize the trilaminar structure. Our study suggests that articular cartilage surface, thickness, and signal intensity can be studied accurately with SE PD and T2 sequences, combined with a GE T1 sequence.