Urinary tract infections are the most common urologic disease in the United States and annually account for over 7 million office and 1 million emergency department visits. In adults, diagnosis of urinary tract infection is typically based on characteristic clinical features and abnormal laboratory values. Imaging is usually reserved for patients who do not respond to therapy and for those whose clinical presentation is either atypical or potentially life threatening. Urinary tract infection typically originates in the urinary bladder; when it migrates to the kidney or is seeded there hematogenously, a tubulointerstitial inflammatory reaction ensues, involving the renal pelvis and parenchyma. The condition is characterized as pyelonephritis. Complicated and uncomplicated pyelonephritis, xanthogranulomatous pyelonephritis, and tuberculosis are all urinary tract infections for which imaging evaluation adds diagnostic information important for patient care. Computed tomography (CT), when performed before, immediately after, and at delayed intervals from contrast material injection, is the preferred modality for evaluating acute bacterial pyelonephritis. CT is also preferred over conventional radiography and ultrasonography (US) for assessing emphysematous pyelonephritis. Xanthogranulomatous pyelonephritis is a chronic granulomatous process, induced by recurrent bacterial urinary tract infection. Although US is useful in the diagnosis of this condition, CT is the main imaging tool, as it provides highly specific findings and accurate assessment of the extrarenal extent of disease, which is essential for surgical planning. The increasing prevalence of tuberculosis and continued emergence of antibiotic-resistant strains have significance for genitourinary radiologists, as the urinary tract is the most common extrapulmonary site of tuberculosis. Familiarity with the renal manifestations of the disease--pelvoinfundibular strictures, papillary necrosis, cortical low-attenuation masses, scarring, and calcification--will help in the diagnosis, even in the absence of documented pulmonary disease.

Pancreatic neoplasms are rare in children and have a different histologic spectrum and prognosis than those in adults. In general, these tumors are well demarcated with expansile rather than infiltrating growth patterns. They may be quite large at diagnosis, and central cystic necrosis is common. They infrequently cause biliary duct obstruction. The imaging appearance of each neoplasm reflects its pathologic features. Pancreatoblastoma is the most common pancreatic neoplasm in young children. At imaging, pancreatoblastomas are heterogeneous and often multilocular with hyperechoic and enhancing septa. Solid-pseudopapillary tumor occurs in adolescent girls. It is heterogeneous in internal architecture, with a mixture of solid and cystic hemorrhagic and necrotic elements. This tumor is distinguished by its fibrous capsule and hemorrhagic nature, which are best shown at magnetic resonance imaging as a dark rim on T1- or T2-weighted images and hyper-intense foci on T1-weighted images, respectively. Islet cell tumors in children are insulinomas or gastrinomas. These tumors manifest early due to hormonal syndromes and are distinguished by their small size, homogeneous appearance, and intense enhancement with intravenous contrast material. All pancreatic neoplasms in children are capable of producing metastases, usually to the liver and lymph nodes; however, on the whole, these tumors have a better clinical outcome than most pancreatic tumors in adults. Knowledge of the differential diagnosis of pancreatic masses in children and their relatively good prognosis may promote correct preoperative diagnosis and appropriate treatment.

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Needle track seeding following image guided needle biopsy is a known but uncommon complication in the workup of hepatocellular carcinoma. We present the case of a 55 year-old male who was found to have a recurrent hepatocellular carcinoma in the rectus sheath five years following a CT guided biopsy with the biopsy needle passing through the anterior abdominal wall muscles.