PurposeThe aims of this study were to present the ultrasonographic (US) features of metastatic renal cell carcinoma (RCC) in the thyroid gland and to evaluate the diagnostic utility of fineneedle aspiration (FNA) and core needle biopsy (CNB).MethodsEight patients with nine metastatic RCC nodules in the thyroid glands who were treated from January 2002 to March 2015 in a single tertiary hospital were consecutively selected and retrospectively reviewed. US features and clinical history were obtained from the institution’s medical database. FNA was performed nine times on eight nodules and CNB was performed six times on six nodules. The diagnostic utility of FNA and CNB was evaluated.ResultsAll nine nodules showed mass formation without diffuse thyroid involvement. On ultrasonography, metastatic RCC nodules were solid (100%), hypoechoic (100%), and ovalshaped nodules with a well-defined smooth margin (88.9%) and increased vascularity (100%, with 55% showing extensive vascularity). No calcifications were noted in any nodules. Lymph node metastasis and direct extension to nearby structures beyond the thyroid gland were not found. One FNA (11%) was able to confirm metastatic RCC, whereas all six CNBs confirmed metastatic RCC.ConclusionMetastatic RCC appears as oval-shaped hypoechoic solid nodules with well-defined smooth margins, no calcifications, and increased vascularity on ultrasonography. Characteristic US features along with a previous history of RCC should raise clinical suspicion, and CNB should be performed to make an accurate diagnosis.

Metal implants not only deteriorate image quality, but also increase radiation exposure. The purpose of this study was to evaluate the effect of metal hip prosthesis on absorbed radiation dose and assess the efficacy of organ dose modulation (ODM) and metal artifact reduction (MAR) protocols on dose reduction. An anthropomorphic phantom was scanned with and without bilateral metal hip prostheses, and surface and deep level radiation doses were measured at the abdomen and pelvis. Finally, the absorbed radiation doses at pelvic and abdominal cavities in the reference, ODM, and two MAR scans (Gemstone spectral imaging, GE) were compared. The Mann Whitney-U test and Kruskal-Wallis test were performed to compare the volume CT dose index (CTDI vol ) and mean absorbed radiation doses. Unilateral and bilateral metal hip prostheses increased CTDI VOL by 14.4% and 30.5%, respectively. MAR protocols decreased absorbed radiation doses in the pelvis. MAR showed the most significant dose reduction in the deep pelvic cavity followed by ODM. However, MAR protocols increased absorbed radiation doses in the upper abdomen. ODM significantly reduced absorbed radiation in the pelvis and abdomen. In conclusion, metal hip implants increased radiation doses in abdominopelvic CT scans. MAR and ODM techniques reduced absorbed radiation dose in abdominopelvic CT scans with metal hip prostheses.

Magnetic resonance imaging (MRI) is an essential modality for the diagnosis of musculoskeletal system defects because of its higher soft-tissue contrast and spatial resolution. With the recent development of MRI-related technology, faster imaging and various image plane reconstructions are possible, enabling better assessment of three-dimensional musculoskeletal anatomy and lesions. Furthermore, the image quality, diagnostic accuracy, and acquisition time depend on the MRI protocol used. Moreover, the protocol affects the efficiency of the MRI scanner. Therefore, it is important for a radiologist to optimize the MRI protocol. In this review, we will provide guidance on patient positioning; selection of the radiofrequency coil, pulse sequences, and imaging planes; and control of MRI parameters to help optimize the MRI protocol for the six major joints of the musculoskeletal system.