Actinomycosis is a chronic suppurative bacterial infection caused by Actinomyces species. Actinomyces israelii is the organism most commonly found in human disease. Actinomycosis usually manifests with abscess formation, dense fibrosis, and draining sinuses. The disease is further characterized by the tendency to extensively spread beyond normal fascial and connective tissue planes. Actinomycosis occurs most commonly in the cervicofacial region (50%-65%), followed by the thoracic (15%-30%) and abdominopelvic (20%) regions, but rarely involves the central nervous system. Most cases of cervicofacial actinomycosis are odontogenic in origin. In the acute form, cervicofacial disease can manifest with soft-tissue swelling, a painful pyogenic abscess, or a mass lesion. In the subacute to chronic form, a painless indurated mass can spread to the skin, leading to draining sinus tracts. Thoracic manifestations include parenchymal, bronchiectatic, and endobronchial actinomycosis. At computed tomography, pulmonary actinomycosis usually appears as chronic segmental airspace consolidation containing necrotic low-attenuation areas with peripheral enhancement. Abdominopelvic actinomycosis preferentially involves the ileocecal region, ovary, and fallopian tube. The imaging findings favoring abdominopelvic actinomycosis include strong enhancement in the solid portion of the mass after contrast material administration, small rim-enhancing abscesses within the mass, and extensive inflammatory extensions. Actinomycosis in the central nervous system may produce brain abscess, meningitis, subdural empyema, actinomycetoma, and spinal and cranial epidural abscess. In general, actinomycosis responds well to antibiotic therapy, but long-term follow-up after treatment is needed because of frequent relapses.

Our objective is to describe the characteristic CT findings of gastrointestinal (GI) tract perforations at various levels of the gastrointestinal system. It is beneficial to localize the perforation site as well as to diagnose the presence of bowel perforation for planning the correct surgery. CT has been established as the most valuable imaging technique for identifying the presence, site and cause of the GI tract perforation. The amount and location of extraluminal free air usually differ among various perforation sites. Further, CT findings such as discontinuity of the bowel wall and concentrated free air bubbles in close proximity to the bowel wall can help predict the perforation site. Multidetector CT with the multiplanar reformation images has improved the accuracy of CT for predicting the perforation sites.

Purpose: To evaluate the efficacy of diffusion-weighted imaging (DWI) on 3 Tesla (T) MR imaging to predict the tumor response to neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.Materials and Methods: Thirty-five patients who underwent neoadjuvant CRT and subsequent surgical resection were included. Tumor volume was measured on T2-weighted MR images before and after neoadjuvant CRT and the percentage of tumor volume reduction was calculated. The apparent diffusion coefficient (ADC) value was measured on the DWI before and after neoadjuvant CRT, and the change of ADC (D ADC) was calculated. The histopathologic response was categorized either as a responder to CRT or as a nonresponder. The relationship between the ADC parameters and the percentage of tumor volume reduction or histopathologic response was then evaluated.Results: There was a significant correlation between tumor volume reduction and pre-CRT ADC and D ADC, respectively (r ¼ À0.352, r ¼ 0.615). Pre-CRT ADC of the histopathologic responders was significantly lower than that of the histopathologic nonresponders (P ¼ 0.034). D ADC of the histopathologic responders was significantly higher than that of the histopathologic nonresponders (P < 0.005).Conclusion: DWI on 3T MR imaging may be a promising technique for helping to predict and monitor the treatment response to neoadjuvant CRT in patients with locally advanced rectal cancer.

The incidence, histologic distribution, and clinical manifestations of ovarian tumors in the pediatric population are distinct from those in adults. Although ovarian neoplasms in childhood and adolescence are rare, the diagnosis should be considered in young girls with abdominal pain and a palpable mass. Differential diagnosis in children and adolescents with ovarian tumors should be conducted on the basis of unique clinical manifestations, elevated serum tumor marker levels, and distinctive imaging findings. Although the clinical manifestations are nonspecific and may overlap, they may assist in diagnosis of some types of ovarian tumors. Children who present with a palpable mass or symptoms of precocious puberty have a high likelihood of malignancy. Many ovarian tumors are associated with abnormal hormonal activity and/or abnormal sexual development. Elevated levels of serum tumor markers, including α-fetoprotein, the beta subunit of human chorionic gonadotropin, and CA-125, raise concern for ovarian malignancies. However, negative tumor markers do not exclude the possibility of malignancy. Identification of imaging features at ultrasonography, computed tomography, and magnetic resonance imaging can help differentiate benign from malignant ovarian tumors and, in turn, plays a crucial role in determining treatment options. At imaging, malignant ovarian tumors usually appear predominantly solid or heterogeneous and are larger than benign tumors. Because surgery is the primary treatment for ovarian tumors, ovarian salvage with fertility preservation and use of a minimally invasive surgical technique are important in children and adolescents.

Hyaluronic acid (HA) is a nonsulfated glycosaminoglycan and a major component of the extracellular matrix. HA is overexpressed by numerous tumor cells, especially tumor-initiating cells. HA-based nanomaterials play in importance role in drug delivery systems. HA is used in various types of nanomaterials including micelle, polymersome, hydrogel, and inorganic nanoparticle formulations. Many experiments show that HA-based nanomaterials can serve as a platform for targeted chemotherapy, gene therapy, immunotherapy, and combination therapy with good potential for future biomedical applications in cancer treatment.