Metallic artifact at orthopedic magnetic resonance (MR) imaging continues to be an important problem, particularly in the realm of total joint arthroplasty. Complications often follow total joint arthroplasty and can be expected for a small percentage of all implanted devices. Postoperative complications involve not only osseous structures but also adjacent soft tissues-a highly problematic area at MR imaging because of artifacts from metallic prostheses. Without special considerations, susceptibility artifacts from ferromagnetic implants can unacceptably degrade image quality. Common artifacts include in-plane distortions (signal loss and signal pileup), poor or absent fat suppression, geometric distortion, and through-section distortion. Basic methods to reduce metallic artifacts include use of spin-echo or fast spin-echo sequences with long echo train lengths, short inversion time inversion-recovery (STIR) sequences for fat suppression, a high bandwidth, thin section selection, and an increased matrix. With care and attention to the alloy type (eg, titanium, cobalt-chromium, stainless steel), orientation of the implant, and magnetic field strength, as well as use of proprietary and nonproprietary metal-suppression techniques, previously nondiagnostic studies can yield key diagnostic information. Specifically, sequences such as the metal artifact reduction sequence (MARS), WARP (Siemens Healthcare, Munich, Germany), slice encoding for metal artifact correction (SEMAC), and multiacquisition with variable-resonance image combination (MAVRIC) can be optimized to reveal pathologic conditions previously hidden by periprosthetic artifacts. Complications of total joint arthroplasty that can be evaluated by using MR imaging with metal-suppression sequences include pseudotumoral conditions such as metallosis and particle disease, infection, aseptic prosthesis loosening, tendon injury, and muscle injury.

Subjects and MethodsFourteen symptomatic patients underwent sonography of the patellar tendon, using a high frequency linear transducer ( 10 MHz) on an HDI 3000 scanner (Advanced Technology Laborato ties, Bothell, WA).The study cohort included five females and nine males who were 11â€"43 years old (mean, 24 years old). Six patients had bilateral symptoms. and eight had unilateral symptoms.The examination consisted of gray-scale and color Doppler sonography of the right and left patellar tendons of patients with unilateral and bilateral symptoms. The patellar tendon was scanned with the transducer oriented parallel to the long axis of the tendon for longitudinal images and perpendic ular to the long axis of the tendon for transaxial images. On gray-scale sonography,the anteropos tenor dimension of the proximal patellar tendon was measured. If a hypoechoic region was seen within the proximal tendon. it was measured. Also. distortion of the normal parallelism of the tendon fibers was assessed. Color flow Doppler sonogra phy was then used to evaluate the tendon. Care was taken to ensure that the sonographic settings were the same for the right and left patellar ten dons. The examination was considered to show pa tellar tendinosis when increased flow was detected in the tendon at the site of gray-scale abnormality (Fig. I ). The values for sensitivity. specificity, and the kappa statistic of flow revealed by Doppler sonography versus gray-scale sonography were determined using version 5.3 of True Epistat soft ware (Epistat, Richardson,TX). Gray-scale and Doppler sonography showed excellent agreement for findings of patellar tendinosis (K = .92). Results Color flow DiscussionOur preliminary data show that color flow

Although systematic plus targeted biopsy was the most accurate biopsy method to detect cribriform morphology, biopsy sensitivity and specificity remained poor.

Reduced visibility of cribriform pattern on multiparametric magnetic resonance imaging has significant ramifications for prostate cancer detection, surveillance and focal therapy.

No abstract