Middle patellar tendon to posterior cruciate ligament (PT-PCL) and normalized PT-PCL : new magnetic resonance indices for tibial tubercle position in patients with patellar instability

BACKGROUND: To demonstrate whether the distance between the middle point of the patellar tendon and posterior cruciate ligament (PT-PCL) calculated on a single axial MR image could be an alternative measure to tibial tubercle-PCL (TT-PCL) distance for TT lateralization without the need of imaging processing. To show that normalization of PT-PCL (nPT-PCL) against the maximum diameter of the tibial plateau may help to identify patients with patellar instability (PI). METHODS: MR scans of 30 patients (13 females, age 32\u202f\ub1\u202f13\u202fyears) with known PI and 60 patients (31 females, age 39\u202f\ub1\u202f19\u202fyears) with no history of PI were reviewed. Two operators calculated TT-PCL, and PT-PCL nPT-PCL. Intraclass correlation coefficient, Student's t-test, Receiver Operator Characteristic curves, Spearman's Rho and McNemar's test were used. RESULTS: Interobserver reproducibility was 0.894 for PT-PCL for TT-PCL (95% CI\u202f=\u202f0.839-0.930) and 0.866 for TT-PCL (95% CI\u202f=\u202f0.796-0.912). The PT-PCL was 23.5\u202f\ub1\u202f3.8\u202fmm in patients and 20.0\u202f\ub1\u202f2.7\u202fmm in controls (P\u202f<\u202f0.001). The TT-PCL was 22.9\u202f\ub1\u202f3.9\u202fmm in patients and 20.5\u202f\ub1\u202f2.7\u202fmm in controls (P\u202f=\u202f0.002). Correlation between the PT-PCL and TT-PCL was R\u202f=\u202f0.838, P\u202f<\u202f0.001. The PT-PCL had 66.6% (95% CI\u202f=\u202f0.542-0.790) diagnostic yield. The nPT-PCL was significantly higher in patients (0.302\u202f\ub1\u202f0.03) than controls (0.271\u202f\ub1\u202f0.03; P\u202f<\u202f0.001) with 73.9% (95% CI\u202f=\u202f0.628-0.851) diagnostic yield. CONCLUSION: The PT-PCL correlated with TT-PCL, with 66.6% diagnostic yield. The nPT-PCL may represent an additional index, with 73.9% diagnostic yield

Solid bone tumors of the spine : Diagnostic performance of apparent diffusion coefficient measured using diffusion-weighted MRI using histology as a reference standard

Purpose To assess the diagnostic performance of mean apparent diffusion coefficient (mADC) in differentiating benign from malignant bone spine tumors, using histology as a reference standard. Conventional magnetic resonance imaging (MRI) sequences have good reliability in evaluating spinal bone tumors, although some features of benign and malignant cancers may overlap, making the differential diagnosis challenging. Materials and Methods In all, 116 patients (62 males, 54 females; mean age 59.5\u2009\ub1\u200914.1) with biopsy-proven spinal bone tumors were studied. Field strength/sequences: 1.5T MR system; T1-weighted turbo spin-echo (repetition time / echo time [TR/TE], 500/13 msec; number of excitations [NEX], 2; slice thickness, 4\u2009mm), T2-weighted turbo spin-echo (TR/TE, 4100/102 msec; NEX, 2; slice thickness, 4\u2009mm), short tau inversion recovery (TR/TE, 4800/89 msec; NEX, 2; slice thickness, 4\u2009mm, IT, 140 msec), axial spin-echo echo-planar diffusion-weighted imaging (DWI) (TR/TE 5200/72 msec; slice thickness 5\u2009mm; field of view, 300; interslice gap, 1.5\u2009mm; NEX, 6; echo-planar imaging factor, 96; no parallel imaging) with b-values of 0 and 1000 s/mm\ub2, and 3D fat-suppressed T1-weighted gradient-recalled-echo (TR/TE, 500/13 msec; slice thickness, 4\u2009mm) after administration of 0.2\u2009ml/kg body weight gadolinum-diethylenetriamine pentaacetic acid. Two readers manually drew regions of interest on the solid portion of the lesion (hyperintense on T2-weighted images, hypointense on T1-weighted images, and enhanced after gadolinium administration on fat-suppressed T1-weighted images) to calculate mADC. Histology was used as the reference standard. Tumors were classified into malignant primary tumors (MPT), bone metastases (BM), or benign primary tumors (BPT). Statistical tests: Nonnormality of distribution was tested with the Shapiro\u2013Wilk test. The Kruskal\u2013Wallis and Mann\u2013Whitney U-test with Bonferroni correction were used. Sensitivity and specificity of the mADC values for BM, MPT, and BPT were calculated. Approximate receiver operating characteristic curves were created. Interobserver reproducibility was evaluated using the intraclass correlation coefficient (ICC). Results The mADC values of MPT (n\u2009=\u200935), BM (n\u2009=\u200965), and BPT (n\u2009=\u200916) were 1.00\u2009\ub1\u20090.32 (0.59\u20132.10) 7 10 123 mm2/s, 1.02\u2009\ub1\u20090.25 (0.73\u20131.96) 7 10 123 mm2/s, 1.31\u2009\ub1\u20090.36 (0.83\u20132.14) 7 10 123 mm2/s, respectively. The mADC was significantly different between BPT and all malignant lesions (BM+MPT) (P < 0.001), BM and BPT (P\u2009=\u20090.008), and MPT and BPT (P\u2009=\u20090.008). No difference was found between BM and MPT (P\u2009=\u20090.999). An mADC threshold of 0.952 7 10 123 mm2/s yielded 81.3% sensitivity, 55.0% specificity. Accuracy was 76% (95% confidence interval [CI]\u2009=\u200963.9%\u201388.1%). Interobserver reproducibility was almost perfect (ICC\u2009=\u20090.916; 95% CI\u2009=\u20090.879\u20130.942). Conclusion DWI with mADC quantification is a reproducible tool to differentiate benign from malignant solid tumors with 76% accuracy. The mADC values of BPT were statistically higher than that of malignant tumors. However, the large overlap between cases may make mADC not helpful in a specific patient. Level of Evidence: 3 Technical Efficacy: Stage