A 36-year-old Mexican female with a slowly growing foot mass was referred to orthopedic surgery clinic for further evaluation. Foot magnetic resonance imaging revealed an infiltrative soft tissue mass along the dorsal aspect of the fourth metatarsal. T2-weighted images revealed multiple central low-signal "dots" surrounded by areas of bright signal intensity, known as the "dot-in-circle" sign, which is highly specific for mycetoma. Surgical biopsy confirmed the diagnosis of bacterial mycetoma in this patient. Mycetoma can lead to progressive deformity and loss of function, as well as possible limb amputation in the case of delayed diagnosis or misdiagnosis. The "dot-in-circle" sign on magnetic resonance imaging can assist in rendering a final diagnosis and distinguish mycetoma from other etiologies of a soft tissue mass, such as a sarcoma or benign soft tissue lesions.

Decreasing radiation dose to patients is an important and apropos topic in this era of rapidly growing medical imaging volumes [ 1 Yu L. Liu X. Kofler J. et al. Radiation dose reduction in computed tomography: techniques and future perspective. Imaging Med. 2009; 1: 65-84 Crossref PubMed Google Scholar ]. Dose optimization projects often target certain percentage dose decreases or threshold estimated doses and make changes, which are tested for diagnostic image quality utilizing phantom or clinical scans [ 2 Chang K. Collins S. Li B. Mayo-Smith W. Optimizing CT technique to reduce radiation dose: effect of changes in kVp, iterative reconstruction, and noise index on dose and noise in a human cadaver. Radiol Phys Technol. 2017; 10: 180-188 Crossref PubMed Scopus (5) Google Scholar , 3 Tsapaki V. Aldrich J. Sharma R. et al. Dose reduction in CT while maintaining diagnostic confidence: diagnostic reference levels at routine head, chest, and abdominal CT—IAEA-coordinated research project. Radiology. 2016; 240: 828-834 Crossref Scopus (105) Google Scholar ].

To analyze the impact of pelvic computed tomography (CT) technique optimization on estimated dose and subjective and objective image quality.

Chronic pelvic pain syndrome is commonly caused by nerve injury, inflammation, or entrapment. Owing to the complex anatomy and branching patterns of pelvic nerves, pelvic neuropathies are often difficult to illustrate and diagnose. High-resolution 3-T magnetic resonance neurography is a promising technique for the evaluation of peripheral neuropathy. In this article, the authors discuss the normal anatomy of major pelvic nerves, technical considerations of high-resolution imaging, and normal and abnormal imaging appearances with relevant case examples.

Accurate diagnosis and prompt therapy of musculoskeletal infections are important prognostic factors. In most cases, clinical history, examination and laboratory findings help one make the diagnosis, and routine magnetic resonance imaging (MRI) is useful to identify the extent of the disease process. However, in many situations, a routine MRI may not be specific enough especially if the patient cannot receive contrast intravenously, thereby delaying the appropriate treatment. Diffusion-weighted imaging (DWI) can help in many such situations by providing additional information, accurate characterization and defining the extent of the disease, so that prompt treatment can be initiated. In this article, we illustrate the imaging findings of the spectrum of musculoskeletal infections, emphasizing the role of DWI in this domain.KEY POINTS:• Abscess in background cellulitis is detected on DWI. • Infectious tenosynovitis shows diffusion restriction as compared to mechanical tenosynovitis. • Pyomyositis with abscess can be differentiated from diabetic myonecrosis on DWI. • Intraosseous abscess is bright on DWI versus devitalized tissue, sequestrum and air. • DWI can be used to differentiate spine infection from simple Modic changes.

•Significant CT dose reduction can produce adequate subjective image quality.•Lower BMI is associated with larger dose reduction.•More DLP reduction is achieved in women than men.