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Medical radiation currently accounts for an increasing percentage (approximately 50%) of the total radiation exposure for the US population (previously about 15%) (moderate evidence). Children are 2–5 (some cite up to 10) times more sensitive to radiation than adults (moderate evidence). There are no data that prove a direct link between low-level radiation from diagnostic imaging and cancer. The best data regarding long-term effects of low-level radiation (100–150 mSv) exposure come from the longitudinal survivor study (LSS) of atomic bomb survivors (moderate evidence). Most major medical and scientific organizations accept the linear, no-threshold model as the preferred model for low-level radiation and cancer risk estimation. The lifetime risk of fatal cancer from a single (relatively high dose) CT in a child has been estimated to be 1:1,000 (limited to moderate evidence).

Children with clinically suspected IBD should have both upper and lower endoscopies as part of the initial workup (strong evidence). Fluoroscopic small bowel follow-through (SBFT) studies are typically performed as part of the initial diagnosis (limited evidence). Wireless capsule endoscopy (WCE) is a safe, moderately sensitive test for the detection of small bowel inflammatory changes and should be utilized in patients without small bowel obstruction and when other diagnostic small bowel exams are negative. However, the specificity and positive predictive value need to be further established (limited evidence). MRI is superior to CT and is the preferred initial diagnostic and follow-up imaging exam of perirectal and perianal disease in Crohn’s disease (CD) patients (moderate–strong evidence). About 70–80% of CD patients and 30–40% of UC patients will require surgery for disease refractory to medical therapy, or severe disease with complications, or risk of malignancy (UC) (moderate evidence). Repeat imaging with SBFT and CT results in significant ionizing radiation exposure and risk of later cancer induction so that alternative imaging methods, MRI and US, should be used (limited evidence).

Nephrolithiasis in Adults Low radiation dose, noncontrast-enhanced computed tomography (MDCT) with 2.5-mm image reconstruction in at least one plane is the test of choice for the patient with a suspected obstructing ureteral stone. In the absence of an available MDCT scanner, intravenous urography (IVU) or a combination of plain radiograph (KUB) and ultrasonography (US) should be performed (moderate evidence). Plain radiograph may be used to follow the descent of stones along the ureter (moderate evidence). For the pregnant patient when US is not diagnostic, MRI avoids ionizing radiation and may be useful with suspected nephroureterolithiasis (insufficient evidence).

This is a book that will appeal to an audience of radiologists, pediatricians, primary care physicians, residents and fellows, midlevel providers, and others in the fields of diagnostic radiology and pediatric radiology who request imaging for children. Through a review of the literature and an algorithmic approach, the authors provide a guide to efficient imaging of specific clinical problems in children while minimizing unnecessary radiation risk and efficiently using health care dollars. A total of 41 chapters are included, with sections on neuroimaging, the musculoskeletal system, the chest, the abdomen, and prenatal imaging. The first 3 chapters address the principles of evidencebased imaging, a critical assessment of the literature with regard to error and bias, and radiation risk from medical imaging in children. Other chapters address common issues in pediatric imaging such as nonaccidental trauma, neuroimaging of seizures, mediastinal masses, congenital heart disease, developmental dysplasia of the hip, and urinary tract infection. Each chapter opens with specific issues and key points to address them. Each clinical entity is further described with definition and pathophysiology, epidemiology, overall cost to society, clinical and laboratory predictors, goals of imaging, and the methodology used in the review of the literature. The key imaging issues are then further discussed, with citations. Imaging algorithms are included where appropriate, and questions for further research are provided. At the end of each chapter are imaging case studies with classic imaging findings, followed by references. Using this format, the book often concisely answers the reader’s question in the well-written initial paragraphs, rather than leaving one to complete the entire chapter and summarize on one’s own. Each chapter, although not long (usually 12‐15 pages, with 30 pages being the longest), is packed with highly useful information. Many chapters include imaging protocols. Limitations of the book include its lack of detail on the topics of neck, liver, and biliary tract imaging. Suggestions for the next edition include chapters on complications of solid-organ and stem cell transplantations and on imaging for pediatric hypertension. I expected to be overwhelmed by the book but found it enjoyable. There was no such reference 10 years ago, after the panic of late January 2001 initiated by lay press articles regarding pediatric CT dose and cancer. Pediatric radiology as a specialty responded by developing more thoughtful processes and better imaging methods, many of which are summarized in this commendable book.

Key Points: □ Child abuse is a serious health problem with severe long-term consequences and high societal costs (strong evidence). □ Child abuse is both underdetected and underreported, and the role of imaging is a critical part of the investigation of abuse (moderate evidence). □ Radiographic skeletal survey is the main diagnostic tool in the diagnosis of skeletal injuries in both living and dead children (moderate evidence). □ Repeat skeletal surveys can clarify and substantiate initially equivocal findings (moderate evidence). □ Skeletal scintigraphy can be used as an adjunct to the skeletal survey (moderate evidence). □ Infant deaths are most likely due to head trauma, whereas toddlers are more likely to die from blunt abdominal trauma (strong evidence).

■ Skilled clinical examiners are capable of detecting the vast majority of developmental dysplasia of the hip (DDH) in neonates, and this remains the primary screening method in the United States. Ultrasound (US) is no better than these examiners but may improve DDH diagnosis or exclusion for less-experienced clinical examiners (strong evidence).

■ Children with clinically suspected IBD should have both upper and lower endoscopies as part of the initial workup (strong evidence). Fluoroscopic small bowel follow-through studies are typically performed as part of the initial diagnosis (limited evidence).

■ Medical radiation currently accounts for an increasing percentage (approximately 50%) of the total radiation exposure for the US population (previously about 15%) (moderate evidence).

■ Malrotation of the bowel is associated with risk of intestinal volvulus and can be fatal (strong evidence). Volvulus is a surgical emergency that is treated with the Ladd procedure (strong evidence).

The standard medical education in Western medicine has emphasized skills and knowledge learned from experts, particularly those encountered in the course of postgraduate medical education, and through national publications and meetings. This reliance on experts, referred to by Dr. Paul Gerber of Dartmouth Medical School as “eminence-based medicine” (1), is based on the construct that the individual practitioner, particularly a specialist devoting extensive time to a given discipline, can arrive at the best approach to a problem through his or her experience. The practitioner builds up an experience base over years and digests information from national experts who have a greater base of experience due to their focus in a particular area. The evidence-based imaging (EBI) paradigm, in contradistinction, is based on the precept that a single practitioner cannot through experience alone arrive at an unbiased assessment of the best course of action. Assessment of appropriate medical care should instead be derived through evidence-based process. The role of the practitioner, then, is not simply to accept information from an expert, but rather to assimilate and critically assess the research evidence that exists in the literature to guide a clinical decision (2–4).

■ The presence of fever, in the setting of an appropriately collected urine specimen and positive urine culture, reasonably distinguishes between cystitis (lower tract) and pyelonephritis (upper tract) infections (moderate evidence).