Most information about imaging the abdominal contents, including the gastrointestinal and genitourinary systems, fits nicely into an organ-by-organ framework. However, this approach makes it difficult to discuss, without unwanted redundancy, diseases or conditions that have manifestations throughout the abdomen and beyond.

For this reason, we have introduced into the 2nd edition of this textbook a new section, entitled “Abdominal Manifestations of Systemic Conditions.”

Since many systemic disorders affect lymph node groups, neural structures, or major vessels throughout the abdomen, we provide some medical illustrations in this introduction as a helpful reminder of important anatomical considerations.

Congenital syndromes, such as multiple endocrine neoplasia (MEN), neurofibromatosis, tuberous sclerosis, and von Hippel-Lindau, are now presented with their protean manifestations of tumors and tumor-like conditions in multiple organs. Tables in this introduction provide a quick reference to the most common and associated features of these important syndromes. It is important for radiologists to understand the varied manifestations of these congenital disorders for accurate detection, staging, and surveillance of these patients. Moreover, radiologists are often the first to recognize manifestations of a congenital syndrome, as the clinical presentations are often quite varied among affected individuals. Although the congenital syndromes that predispose patients to various neoplastic or metabolic diseases have a genetic basis, some develop as spontaneous mutations rather than being inherited in an autosomal dominant or recessive pattern.

Multiple endocrine neoplasia syndromes are caused by genetic defects and affect about 1 in 5,000-50,000 people. These syndromes predispose patients to tumor development within 2 or more components of the endocrine system.

Among the most interesting and challenging of the congenital syndromes are the phakomatoses or neurocutaneous syndromes. These include neurofibromatosis, tuberous sclerosis, and von Hippel-Lindau disease. As the name implies, these patients are at risk for many benign and malignant neoplasms affecting the skin, CNS, and multiple abdominal viscera. Although all of these exhibit an autosomal dominant pattern of inheritance, many affected individuals have no positive family history. Neurofibromatosis is the most common of the phakomatoses (1 in 3,000), while von Hippel is the least common (1 in 30,000-50,000).

Systemic infections, including AIDS, tuberculosis, and mononucleosis, are also discussed, along with important clues to help identify the infectious and neoplastic disease that they may cause or simulate.

Degenerative conditions, such as sarcoidosis, and vascular disorders are rarely limited to a single organ. These are presented in all their guises, along with tips as to how to address differential diagnosis.

Foreign bodies may be encountered throughout the gastrointestinal and genitourinary system and are well-known to be found repeatedly in certain individuals. Now, the reader will find these discussed in a single chapter with expert tips to avoid common pitfalls in diagnosis and management.

Many malignant neoplasms are, by their very nature, systemic processes, such as lymphoma, leukemia, and malignant melanoma. We will feature chapters on “Metastases and Lymphoma” for individual organs; however, this new approach gives us a chance to bring together some general principles about the presentation, diagnosis, and management of these important diseases.

Finally, while some conditions, such as systemic hypotension or hypervolemia, do not represent disease per se, they can result in important clinical and imaging abnormalities that must be recognized to avoid misguided patient management.

Plain radiography maintains an important role for surveillance of some generalized disease processes, such as the osseous and visceral manifestations of sickle cell anemia or cystic fibrosis.

Ultrasound is an important imaging tool for the evaluation of biliary, vascular, gynecologic, and scrotal pathology but lacks both sensitivity and specificity in evaluating other processes, especially bowel pathology.

Computed tomography (CT) has become the essential tool for the comprehensive evaluation of most traumatic, inflammatory, and neoplastic abdominal processes. In patients with cancer, for instance, the ability to quickly and accurately examine different anatomic areas (thorax, abdomen, and pelvis), organs, and structures of different composition (lung, liver, and bone, for example) is a tremendous advantage. Thus, there is continued growth and popularity of CT even in this era of powerful “competing” modalities, such as positron emission tomography (PET) and magnetic resonance imaging (MR). PET and MR imaging do serve an important role as problem solving tools for evaluating abdominal pathology. MR, with its excellent soft tissue characterization, is particularly helpful in evaluating masses within solid abdominal organs.

Catheter angiography remains the most accurate means of identifying certain vascular disorders and often results in catheter-based therapies in the same setting. For vasculitides, which routinely affect vessels throughout the body, angiography maintains an essential diagnostic and therapeutic role.