The purpose of this study was to evaluate the validity and reliability of a radiographic diagnosis of femoroacetabular impingement (FAI) by a non-radiologist. Symptomatic FAI is prevalent and thought to be a cause of hip osteoarthritis. However, the diagnosis is often delayed by 1-2 years, in large part because radiographic findings are often subtle and clinicians have been unaware of their significance. The purpose of this study was to evaluate the validity of a radiographic diagnosis of FAI by a non-radiologist. A population-based sample of 701 subjects was recruited in Vancouver, Canada. For the current study, 50 subjects were selected-40 randomly from the population sample and 10 from an orthopedic practice with confirmed FAI. An anterior-posterior pelvis and bilateral Dunn radiographs were acquired and read by a fellowship-trained musculoskeletal radiologist and a third-year medical student who received basic training in radiographic signs of FAI. Three radiographic signs were evaluated: the lateral center edge angle, alpha angle and crossover sign. Validity was assessed using sensitivity and specificity, Bland-Altman limits of agreement and kappa. The sample contained 65% women (n = 31), was 62% Caucasian and 38% Chinese and had a mean age of 38.3 years. For correctly diagnosing FAI, the non-radiologist reader had a sensitivity of 0.83 and specificity of 0.87. Intra-rater κ value was 0.72, and prevalence-adjusted bias-adjusted κ was 0.76. This study provides evidence that a non-radiologist can accurately and reliably identify FAI on plain films.

Only a small number of MRI investigations performed included all of the sequences stipulated by consensus guidelines. This is likely due to poor awareness in the imaging community of the guidelines and the rationale behind certain sequences. Radiologists with a sub-speciality interest in neuroradiology should take ownership of this issue and ensure that recommended imaging guidelines are followed.

Radiologists must recognise that there are specific diagnostic criteria for MS that continue to evolve as a result of new research, improved technology and clinical experience and it is crucial that these criteria be applied in daily practice. It should be evident that diagnostic imaging criteria for MS will be most effective when combined with standardised MRI protocols such as those published by the international Consortium of Multiple Sclerosis Centres.

SUMMARY: MR spectroscopy is used to provide in vivo biochemical information about cerebral metabolites. Magnetic field homogeneity secondary to anatomic interfaces, hemorrhage, or necrosis may lead to suboptimal MR spectroscopy. Susceptibility-weighted imaging (SWI) can identify field inhomogeneity and could be used to guide MR spectroscopy voxel placement, leading to higher-quality MR spectroscopy examinations. Proton MR spectroscopy is used in clinical and research MR imaging studies to help differentiate between regions of normal and abnormal brain tissue and to monitor disease progression. Usually, key cerebral metabolites such as N-acetylaspartate (NAA), choline-containing compounds (Cho), and creatine/phosphocreatine (Cr) are identified, and quantitative data or metabolite ratios are measured.1 A homogeneous magnetic field and good signal-to-noise ratio are required for high-quality spectra. Spectral quality may be compromised at both 1.5 and 3T by signal-to-noise ratio issues and by magnetic field inhomogeneity, leading to poor water suppression, increased spectral line widths, and excessive baseline roll. 2,3 Interfaces between bone, air, and soft tissue cause localized perturbations in the magnetic field, and this is typically noted at the skull base adjacent to the sphenoid, frontal, and petrous air cells.If regions of magnetic field heterogeneity are unwittingly included within the sampling voxel by the operator, MR spectroscopy may be suboptimal. Susceptibility-weighted imaging (SWI) is a relatively new imaging sequence that is increasingly routinely used. 4 This sequence can detect subtle signal intensity phase differences within tissues, visualized as a signal intensity image or a phase map. 4 Anatomic regions with increased susceptibility differences can contribute to magnetic field inhomogeneity. Therefore, SWI or phase maps could be used to guide placement of the MR spectroscopy sampling voxel or aid interpretation of poor spectral results. TechniqueMR imaging studies were performed at 1.5T with use of a 12-channel receiver coil (Siemens, Erlangen, Germany). Data from a healthy subject and from a patient with recurrent glioblastoma multiforme were analyzed. We acquired SWI data by using a velocity-compensated radio-frequency-spoiled high-resolution 3D gradient-echo sequence (TR, 49 ms; TE, 40 ms; 72 sections; matrix, 256.177; voxel size, 1.1 ϫ 0.9 ϫ 2 mm). Phase and SWI maps were generated with use of VB15 software (Siemens). We acquired MR spectroscopy data by using a multivoxel point-resolved spectroscopy sequence (TR, 1700 ms; TE, 135 ms; MR spectroscopy voxel size, 10 mm ϫ 10 mm ϫ 15 mm). Fully automated shimming and water suppression were used and peripheral saturation bands placed. A gadolinium-enhanced T1-weighted acquisition (same section prescription as SWI) was used for placement of the multivoxel MR spectroscopy grid.We investigated the relationship between spectral quality and the degree of susceptibility-induced phase distortion (ie, field inhomogeneity) by processing the phase maps...

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